ComparativeAnalysisofUnderstoreyFloristicDiversityand ...downloads.hindawi.com/journals/ijfr/2020/8868824.pdf · 2020. 9. 1. · Table 2:UnderstoreyspeciesfoundintheintensivelyandpoorlymanagedTectona

Research ArticleComparative Analysis of Understorey Floristic Diversity andCarbon Stocks in Poorly and Intensively Managed Tectonagrandis Plantations

A Asare 1 W A Asante2 N Owusu-Prempeh 3 E Opuni Frimpong1 and D Adusu1

1Department of EnvironmentalManagement University of Energy and Natural Resources (UENR) UENR PO Box 214 SunyaniSunyani Ghana2Department of Silviculture and Forest Management Kwame Nkrumah University of Science and Technology (KNUST)Kumasi Ghana3Department of Forest Resources Technology Kwame Nkrumah University of Science and Technology (KNUST) Kumasi Ghana

Correspondence should be addressed to A Asare austinasareuenredugh

Received 19 May 2020 Revised 1 July 2020 Accepted 31 July 2020 Published 1 September 2020

Academic Editor omas Campagnaro

Copyright copy 2020A Asare et alis is an open access article distributed under the Creative CommonsAttribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

e role of forest plantations in carbon sequestration and biodiversity conservation is a topical issue among researchers andpolicymakers globally is study compares understorey floristic diversity and carbon stock of a 15-year-old monoculture Tectonagrandis plantation under intensive and poor management in a dry semideciduous ecological zone of Ghanae study employed anested plot design with twelve (12) 50mtimes 50m plots laid at 50m intervals along a diagonal line transect on both study sites for thesampling of Tectona grandis trees Understorey trees shrubs and climbers were sampled within 10mtimes 10m subplot whilstgrasses and herbs were sampled within 1mtimes 1m quadrats e study revealed a significantly higher understorey species diversityin the intensively managed plantation (Shannon index species richness) compared with that of the poorly managed plantationSimilarly total biomass (18980plusmn 1846Mgha) and carbon stock (9490plusmn 092MgCha) in the intensively managed plantationwere observed to be significantly higher than the poorly managed plantation (biomass 13854plusmn 370Mgha carbon stock6427plusmn 185MgCha) whiles the species composition between the two sites was different (Sorensonrsquos similarity index 047) estudy therefore concludes that silvicultural forest management interventions improve the understorey floristic diversity andcarbon stock in monoculture plantations Consequently the study recommends the adoption of silvicultural interventions inplantation management in Ghana to improve their contributions to carbon sequestration and floristic diversity conservation

1 Introduction

Climate change and biodiversity loss are among the mostprominent environmental challenges in the 21st century [1]ese challenges have therefore received critical global at-tention with many governments researchers and policy-makers debating and developing innovative measures toensure a balance between conservation climate mitigationand development goals [2 3] Also in recent years mosthuman efforts have been aligned towards climate changemitigation and biodiversity conservation including sus-tainable forest management which has been widely recog-nized to possess a huge potential to find lasting solutions tothese environmental challenges [4]

Many researchers have also argued that a collectiveglobal effort aimed at arresting deforestation and forestdegradation together with massive reforestation and affor-estation can play an essential role in addressing thesechallenges [5 6] particularly through the sequestration ofcarbon from the atmosphere and conservation of biodi-versity However despite this recognized potential andconsiderable global efforts towards forest conservation vastareas of natural forests continue to be converted into otherland uses annually [1] For instance the FAO [7] estimatedthat between 2000 and 2010 the global rate of natural forestloss was around 13 million hectares per year With thecontinuous increase in global demand for timber and de-pletion of limited natural forests many countries have

HindawiInternational Journal of Forestry ResearchVolume 2020 Article ID 8868824 13 pageshttpsdoiorg10115520208868824

endorsed commercial plantations establishment as an al-ternative to ease pressure on natural forest resources [1]

Consequently vast areas of degraded forest landsglobally are being converted into plantations of different treespecies (both indigenous and exotic) in single or mixed-species stands According to Payn et al [8] the global coverof plantation forests increased from 1675 million ha in 1990to 2779 million ha in 2015 with a majority of these plan-tations being monocultures of Eucalyptus Pinus AcaciaTectona Picea and Pseudotsuga Among these plantationspecies Tectona grandis has been reported to be the mostvaluable and widely produced species globally with com-mercial plantations in about 70 tropical and subtropicalcountries in Asia Africa America and Oceania [9 10]

Plantations are thus expected to reduce the pressure onthe existing natural forests promote biodiversity conser-vation and carbon sequestration restore degraded forestsreduce soil erosion connect fragmented landscapes andprovide alternative livelihood for forest-fringe communities[1 11 12] According to Nilsson and Schopfhauser [13]plantation establishment could result in 345 million hectaresof new forests that would sequester about 15Gt of carbonper year equivalent to about 30 percent of global anthro-pogenic carbon emissions Niu and Duiker [14] also re-ported that the afforestation of marginal agricultural lands inthe Midwestern United States could offset 6ndash8 percent ofregional CO2 emissions Many studies have also reported thepotential of plantation forests for biodiversity restoration indegraded lands [15 16] However according to Kollert andKleine [9] without appropriate silvicultural interventionsthese services would be severely compromised

e situation in Ghana a sub-Saharan tropical Africancountry is not different from what persists in other coun-tries globally despite the nationrsquos well-established forestpolicies and management plans Population pressure ag-ricultural expansion bush fires unsustainable logging andmining have led to the wanton deforestation and degra-dation of approximately 80 of the primary forest coverwith associated problems such as loss of biodiversity climatechange and loss of livelihoods [11 17] As a result thegovernment of Ghana initiated the National Forest Plan-tation Development Program aimed at integrating socio-economic development and environmental sustainabilityprinciples in the restoration of degraded forest landscapesinto plantation [18] rough this initiative a total of16948976 ha of pure and mixed plantations were estab-lished in degraded forests in Ghana from 2002 to 2012 [12]However according to Foli et al [20] over 50ndash70 of theseplantations are Tectona grandis monocultures largely due toits fast growth market demand economic potential andpest and fire resistance

Despite the significant contributions of Tectonagrandis plantations to the economy of Ghana the specieshas come under serious criticism as many have raisedconcerns among others over its impacts on understoreyspecies diversity carbon stocks and soil nutrient dy-namics [1 21 22] It has also been condemned for itsnegative impact on nontimber forest products of liveli-hood importance and labeled as a threat to livelihood

sustainability in forest-fringe communities [23] How-ever many authors have argued that these negative im-pacts could be reversed through the adoption ofappropriate silvicultural practices in the management ofthese plantations [3[24] According to the authors sil-vicultural management practices such as pruning thin-ning and weeding may play a key role in enhancing theproductivity quality of wood understory diversity andcarbon sequestration potential of plantation forests

Many empirical studies in recent years have thereforegiven substantial attention to the development of modernapproaches and tools to ensure sustainable management offorest plantations Tectona grandis being the most exten-sively grown species globally has received a fair share ofcurrent forestry research attention However majority ofthese studies have largely focused on its genetic variations[25 26] growth performance [27 28] vegetative propa-gation [28] 1998) and market potential [29 30] with only afew studies exploring management techniques to enhance itsproductivity understorey floristic diversity and carbonstock [9 31]

In Ghana studies on plantations have largely focused onfloristic diversity and composition [32] productivity pesttolerance [28] and survival and growth performance [33] inmono and mixed plantations To date limited studies havefocused on the effects of different silvicultural managementtechniques on understorey floristic diversity stand pro-ductivity and carbon stocks [9 31] particularly in thewidely established Tectona grandismonoculture plantationsis study therefore seeks to assess the productivity carbonstock and understorey floristic diversity in Tectona grandisplantation under different silvicultural management regimesin the dry semideciduous ecological zone of Ghana estudy specifically examines the influence of silviculturalmanagement on (a) understorey floristic diversity(b) dendrometric parameters (height and diameter) and(c) carbon stock of Tectona grandis plantation e study isexpected to provide the necessary data to bridge the gap inknowledge on the effects of silvicultural management onfloristic diversity and carbon stock of Tectona grandisplantations It is also expected to provide the necessaryinformation for the development of strategies to improvecurrent plantation schemes for the sustainable managementof plantations

2 Materials and Methods

21 Description of the Study Area e study was conductedin the Asubima Forest Reserve in the dry semideciduousecological zone of Ghana (Figure 1) e Reserve lies withina grid reference of 74135degN 18874degW near AkumadanGhana [34] It covers a total area of 7870 hectares ereserve has a tropical monsoon climate with alternating wetand dry seasons e long-wet season starts around mid-March and ends in mid-July and is followed by a short dryseason until the end of August Its mean annual temperatureis about 26degC e reserve is a habitat of important timberspecies such as Triplochiton scleroxylon Millicia excelsEntandrophragma cylindricum and Pericopsis elata [35]

2 International Journal of Forestry Research

22 Sampling Design and Data Collection A combination ofstratified and systematic sampling techniques was employedin this study Tectona grandis plantations were stratified intotwo different management regimes (ie intensively andpoorly managed) e intensively and poorly managedTectona grandis plantations were both 15 years old (Table 1)

A nested plot design with twelve 50mtimes 50m plots laid at50m intervals along a diagonal line transect at both study sites(the intensively and poorly managed Tectona grandis planta-tion) were used for this study (Figure 2) e plots were ap-propriately laid to eliminate the confounding effects of slope onthe understorey floristic diversity and composition responseswith the aid of a compass and a measuring tape e50mtimes 50mplots were used for samplingTectona grandis treesAlso twelve 10mtimes 10m subplots were established in themiddle of the main plot (ie 50mtimes 50m) to sample theunderstorey trees (20 cm height lt10 cmdbh) shrubs andclimbers due to their sparsely distributed nature Twelve1mtimes 1m quadrats one in the middle of each 10mtimes 10msubplot were laid for the sampling of grasses and herbs Onlyplants with a diameter at breast height (dbh) lt10 cm (seedlingsand saplings) were sampled as regeneration during theunderstorey vegetation sampling [36] Within the 10mtimes 10msubplots all understorey trees (ge2 cmle10 cmdbh) shrubs

(dbh lt10 cm) and climbers were sampled Herbs and grasseswere also sampled within the 1mtimes 1m quadrats Understoreyplants were identified to the species level in the field with theaid of a botanist from the Forest Research Institute of Ghana(FORIG) and photo guide for forest trees in Ghana [27]Voucher specimens of plants that could not be identified on thefield were collected labeled pressed and dried for subsequentidentification through comparisonwith preserved specimens atthe Resource Management Support Centre of the ForestryCommission (RMSC) herbarium in Kumasi Ghana Deadspecies were not considered in this study due to difficulties inidentification e diameter at breast height (DBH) of theTectona grandis trees was measured using a tree caliper anddiameter tape while the height was determined with Vertex IVand Transponder III

23 Estimation of UnderstoreyDiversity Species CompositionSimilarity e diversity and evenness of understorey florafor each plot were determined using the number of speciesper unit area and two widely used indices includingShannon Wienerrsquos diversity index (Hprime) [38] and Pieloursquosevenness index (J) [39]e indices were computed using thefollowing formula

Burkina Faso

Cote drsquolvoire

Togo

0 125 25 5km

Ghana boundary

Forest reserves in Ghana

Asubima forest reserve

N

S

W E

644000000000 648000000000 652000000000 656000000000 660000000000 664000000000

644000000000 648000000000 652000000000 656000000000 660000000000 664000000000

7300

000

0000

073

6000

000

000

7420

000

0000

074

8000

000

000

7300

000

0000

073

6000

000

000

7420

000

0000

074

8000

000

000

Figure 1 Map of Ghana showing the study area

International Journal of Forestry Research 3

Hprime minus 1113944s

1i

pi lnpi (1)

e Pieloursquos evenness index is defined as

J Hprime1113868111386811138681113868

1113868111386811138681113868ln S (2)

where (Hprime) is the Shannon diversity index and lnS is thenatural logarithm of the total number of species

e similarity in species composition between the in-tensively managed and the poorly managed Tectona grandisplantations was evaluated using Sorensonrsquos coefficientsimilarity index (SCSI) defined as follows

SCSI 2c

(a + b + 2c)1113888 1113889 (3)

where c number of species occurring in two sites (com-mon occurrence species) a number of species occurringin site A only and b number of species occurring in site Bonly

SCSI close to 1 indicates areas with most of their speciesin common and for dissimilar areas the value is close to 0Sites with an index lt05 are considered different in terms ofspecies composition whilst sites with an index gt05 areconsidered similar in species composition [40]

50m

Line transect

50m times 50m plot along line transect at 50m intervals

50m

50m 1m times 1m

10m

10m

Figure 2 Experimental plot layout of nested plot design 1mtimes 1m for herbs and grasses 10mtimes 10m plot for sampling climbers shrubsand tree life forms (20 cm height lt10 cmdbh) and 50mtimes 50m plot for sampling Tectona grandis trees

Table 1 Management regimes and their corresponding definitions

Managementregimes Description

Intensivelymanaged

Plantation raised with pruning (8 times in 15 years ie from 2002 to 2009) thinning (600 treesha in 2010 and 450treesha in 2012) and weed control (3 times per year up to 4 years with a mean stocking density of 301)

Poorly managed Plantation raised with no pruning no thinning and weeding was done once a year up to 2 years with amean stockingdensity of 359


24 Tectona grandis Aboveground and Belowground Biomassand Carbon Stock Estimation In each 50mtimes 50 plot thediameter at breast height (DBH in centimeters) and total treeheight (H in meters) of each Tectona grandis trees weremeasured e dendrometric records of the individualTectona grandis trees and the wood specific gravity ρ (gcm3)of Tectona grandis obtained from the global wood densitydatabase [41] were entered into an allometric equation todetermine the aboveground biomass [42]

AGBest 00673 times ρD2H1113872 1113873

0976 (4)

where AGB= aboveground Tectona grandis biomass (kg)ρ=wood specific gravity (gcm3) D=Tectona grandis treediameter in cm (dbh at 13m above the ground) andH= total tree height (m)

Belowground biomass (BGB) of Tectona grandis wasestimated using the allometric equation developed by Kuyahet al [43] as follows

BGBest 0048 times(dbh)2303

(5)

e total biomass for each 50mtimes 50m plot was esti-mated from the total AGB and BGB (kg) and the valuedivided by the area of the sampling plot (2500m2) to obtainthe biomass stock density in kgm2 and converted to Mghae carbon content of each tree in the plots was calculated bymultiplying the modeled dry weight biomass by 05 [44]ecarbon dioxide equivalent (CO2e) was estimated by multi-plying the carbon stock by 367 [45]

25 Statistical Analysis e mean values of Shannon di-versity and Pieloursquos evenness indices dendrometric pa-rameters (diameter and height) total biomass and carbonstocks were subjected to normality and homogeneity ofvariance test is was followed by an independent sample ttest to determine the difference between the intensively andthe poorly managed plantations ose that violated thenormality and equality of variance assumptions werecompared using the MannWhitney nonparametric test Allstatistical analyses were performed using IBM SPSS version21

3 Results

31 Understorey Species Composition A total of 84 under-storey species distributed over 35 families were identified inthe intensively and poorly managed Tectona grandis plan-tations Out of this number the intensively managedplantation recorded 67 species distributed over 32 familieswhile the poorly managed plantation recorded only 43species distributed over 20 families (Table 2) e five mostcommon families in the intensively managed plantationswere Moraceae (6 species) Combretaceae (5 species)Euphorbiaceae (5 species) Rubiaceae (5 species) andSapindaceae (5 species) (Table 3) Common families underthe poorly managed plantation were Gramineae (10 species)Moraceae (5 species) and Papilionaceae (5 species) Sor-ensonrsquos coefficient similarity index (Sorensenrsquos index

hereafter) of understorey floristic species between the in-tensively managed and poorly managed plantations was 047(Table 3) However in terms of life forms Sorensonrsquos indexfor understorey trees grasses shrubs climbers and herbsbetween the intensively and poorly managed plantations was046 057 057 046 and 036 respectively Twenty-threeunderstorey tree species were unique to the intensivelymanaged plantation whereas only 5 tree species were ex-clusive to the poorly managed plantation

32 Comparison of the Overall Understorey Floristic Diversitybetween the Intensively and Poorly Managed Tectona grandisPlantation An independent sample t test was used tocompare the overall understorey mean species diversityrichness and evenness between the intensively and poorlymanaged Tectona grandis plantation Generally speciesrichness in the intensively managed plantation (meanplusmn SE16417plusmn 1479) was significantly higher (t (22) 4210ple 001) compared with that in the poorly managedplantation (9333plusmn 0801) Similarly the understorey vege-tation of the intensively managed plantation was more di-verse (2450plusmn 0086) (t (22) 5807 ple 001) than that of thepoorly managed plantation (1753plusmn 0084) Floristics specieswere more evenly distributed in the intensively managedplantation (0898plusmn 0020) (t (22) 3455 ple 001) thanthose in the poorly managed (0795plusmn 0022) (Table 4)

321 Comparison of Understorey Species Diversity in Termsof Life Forms between the Intensively and Poorly ManagedTectona grandis Plantation e MannWhitney nonpara-metric test showed that the intensively managed Tectonagrandis plantation recorded significantly higher (plt 001)understorey trees and climbers diversity compared with thatof the poorly managed plantation e diversity of grasseswas significantly higher (plt 001) in the poorly managedplantation (Table 5)

Understorey diversity of trees shrubs and climbers wasestimated at the subplot (10mtimes 10m) levels whilst that ofgrasses and herbs was estimated at quadrat (1mtimes 1m)levels

322 Spearmanrsquos Rank Correlation Matrix of the DifferentLife Forms of the Understorey Species Spearmanrsquos rankcorrelation indicated the following life form pairsherbsclimbers (r 0325) shrubsclimbers (r 0128)treesclimbers (r 0305) treesherbs (r 0245) treesshrubs (r 0398) herbsgrasses (r 002) and herbsshrubs(r 0029) recorded a positive correlation though not sta-tistically significant (pgt 001) whilst the following life formpairs shrubsgrasses (r minus0283) and climbersgrassesrecorded nonsignificant (pgt 005) negative correlations(Table 6) However the understorey floristic diversity oftrees and grasses showed a highly significant negative cor-relation (r minus0707 plt 001) suggesting that as understoreygrasses diversity increases understorey trees diversity tendsto decrease significantly (Table 7)


Table 2 Understorey species found in the intensively and poorly managed Tectona grandis plantations

No Family Species Star rating Habit IM PM1 Anarcadiaceae Spondias mombin Green Tree 1 02 Apocynaceae Holarrhena floribunda Green Tree 1 13 Motandra guineensis Green Climber 1 04 Araceae Anchomanes difformis Green Herb 1 15 Asclepiadaceae Gongronema latifolium Green Climber 0 16 Asteraceae Chromolaena odorata Green Shrub 1 17 Bignonaceae Newbouldia laevis Green Tree 0 18 Markhamia tomentosa Green Tree 1 09 Spathodea campanulata Green Tree 1 010 Bombacaceae Ceiba pentandra Pink Tree 1 011 Caesalpiniaceae Griffonia simplicifolia Green Climber 1 112 Mezoneuron benthamianum Green Climber 0 113 Capparaceae Euadenia eminens Blue lowast Tree 1 014 Chrysobalanaceae Maranthes kerstingii Blue lowast Shrub 0 115 Combretaceae Combretum zenkeri Blue lowast Climber 1 016 Combretum cuspidatum Blue lowast Climber 1 117 Combretum racemosum Green Climber 1 018 Combretum smeathmannii NA Climber 1 019 Terminalia glauscens NA Tree 1 020 Compositae Aspilia africana NA Herb 0 121 Spilanthes filicaulis NA Herb 1 022 Synedrella nodiflora NA Herb 1 023 Connaraceae Cnestis ferruginea Green Climber 1 124 Cnestis longiflora Green Climber 1 125 Convolvulaceae Ipomoea hederifolia NA Climber 1 026 Cucurbitaceae Momordica charantia NA Climber 1 027 Cyperaceae Mariscus alternifolius NA Herb 0 128 Dichapetalaceae Dichapetalum madagascariense Green Tree 1 029 Ebenaceae Diospyros monbuttensis Green Tree 1 030 Euphorbiaceae Acalypha ciliata NA Herb 1 031 Alcornea cordifolia Green Shrub 1 032 Croton lobatus NA Herb 1 033 Euphorbia herterophylla NA Herb 1 134 Mallotus oppositifolius Green Shrub 1 135 Gramineae Andropogon tectorum NA Grass 0 136 Imperata cylindrica NA Grass 0 137 Panicum maximum NA Grass 0 138 Pennisetum polystachyum NA Grass 0 139 Pennisetum purpureum NA Grass 0 140 Rottboellia cochinchinensis NA Grass 1 141 Rottboellia exaltata NA Grass 1 142 Setaria barbata NA Grass 1 143 Sorghum arundinaceum NA Grass 1 144 Sporobolus pyramidalis NA Grass 0 145 Loganiaceae Spigelia anthelmia NA Herb 1 046 Meliaceae Trichilia preuriana Green Tree 1 047 Trichilia tessmannii Green Tree 1 048 Menispermaceae Albertisia scandens Gold Climber 1 049 Triclisia dictyophylla Green Climber 1 050 Mimosaceae Albizia adianthifolia Green Tree 1 151 Albizia zygia Green Tree 0 152 Moraceae Antiaris toxicaria Red Tree 1 153 Broussenatia papyrifera Invasive Tree 1 154 Ficus exasperata Green Tree 1 055 Ficus sur Green Tree 0 156 Ficus vogeliana Green Tree 1 057 Milicia excelsa Scarlet Tree 1 158 Morus mesozygia Green Tree 1 159 PalmaeArecaceae Elaeis guineensis Pink Tree 1 160 Pandaceae Microdesmis puberula Green Tree 1 0


33 Dendrometric Parameters of 15-Year-Old Tectona grandisPlantationunder Intensive andPoorManagement emeantotal height (2238plusmn 009m) of Tectona grandis in the in-tensively managed plantation was significantly higher (t(658) 15889 ple 001) compared with that in the poorly

managed plantation (2015plusmn 010m) (Table 8) Similarly themean diameter of Tectona grandis in the intensively man-aged plantation (2799plusmn 022) was significantly higher(t (658) 20476 ple 0001) than that in the poorly managedplantation (2298plusmn 013) (Table 6)

Table 3 Overall understorey species similarity in life forms in the intensively and poorly managed Tectona grandis plantation

Life formsUnique species

Shared species Sorensonrsquos coefficient similarity indexIntensively managed Poorly managed

Trees 23 5 12 046Grasses 0 6 4 057Shrubs 2 1 2 057Climbers 11 3 6 046Herbs 5 2 2 036Overall species 41 17 26 047SCSI lt05 is considered different (dissimilar) in species composition

Table 4 Comparison of mean understorey species diversity richness and evenness in the intensively and poorly managed Tectona grandisplantation

Management regimes Species richness Shannon Wienerrsquos diversity index Pieloursquos evenness

Intensively managed Meanplusmn SE 16417plusmn 1479 2450plusmn 0086 0898plusmn 0020Minndashmax 7000ndash23000 1873ndash2832 0728ndash0964

Poorlyunmanaged Meanplusmn SE 9333plusmn 0801 1753plusmn 0084 0795plusmn 0022Minndashmax 6000ndash1700 1160ndash2274 0647ndash0934

T 4210 5807 3455df 22 22 22p value le0001 le0001 le0001Calculations were done according to the entire study plotsplusmnstandard error

Table 2 Continued

No Family Species Star rating Habit IM PM61 Papilionaceae Baphia nitida Green Tree 1 162 Baphia pubescens Green Tree 0 163 Centrosema pubesens Green Climber 1 164 Dalbergia saxatilis Green Climber 0 165 Gliricidia sepium NA Tree 1 066 Milletia rhodantha Green Tree 0 167 Milletia zechiana Green Tree 1 068 Polygalaceae Carpolobia lutea Green Tree 1 069 Rubiaceae Morinda lucida Green Tree 1 170 Morinda morindoides Green Climber 1 171 Musseanda erythrophylla Green Climber 1 072 Psychotria ivorensis Gold Shrub 1 073 Rothmannia longiflora Green Tree 1 074 Sapindaceae Blighia sapida Green Tree 1 175 Blighia unijugata Green Tree 1 076 Deinbollia grandifolia Green Tree 1 077 Leucanodiscus cupanoides Green Tree 1 078 Paullinia pinnata Green Climber 1 079 Sapotaceae Malanchata alnifolia Green Tree 1 080 Sterculiaceae Cola caricifolia Green Tree 1 181 Cola gigantea Green Tree 1 082 Sterculia tragacantha Green Tree 1 183 Verbenaceae Clerodendron capitatum Green Climber 1 084 Violaceae Rinorea yaundensis Green Tree 1 0

35 841 present 0 absent NA unknown IM intensively managed and PM poorly managed Species in bold with asterisk symbol are rated as blue starspecies while those in bold are rated gold star


34 Total Biomass and Carbon Stock of 15-Year Old Tectonagrandis Plantation under Intensive and Poor ManagementTotal biomass (18980plusmn 1846Mgha) total biomass per tree(063plusmn001 Mgtree) and carbon stock (9490plusmn 092MgCha equivalent to 34828plusmn 34Mg CO2eha) of Tectonagrandis plantation in the intensively managed plantationwere significantly higher (ple 0001) than those in the poorlymanaged plantation (Table 8) However the density of treesin the poorly managed plantation (35900plusmn 2144 treesha)was significantly higher (t (6) =minus2664 p value = 0037) thanthat in the intensively managed plantation (301plusmn 376 treesha) (Table 8)

4 Discussion

41 Understorey Floristic Diversity Richness and Evennessunder Different Management Regimes e role of forestplantations in carbon sequestration and biodiversity

conservation is a topical issue in recent years [46] is studyassessed and compared understorey floristic diversity andcarbon stock of a 15-year-old monoculture Tectona grandisplantation under intensive and poor management in a drysemideciduous ecological zone of Ghana e study revealedsignificantly higher understorey species diversity richnessand evenness in the intensively managed compared withthose in the poorly managed Tectona grandis plantation(Table 7) e high understorey floristic diversity in theintensive compared with the poorly managed plantationscould be attributed to the prevalence of silvicultural practices(weeding pruning and thinning) in the intensively man-aged Tectona grandis plantation ese silvicultural practicesopen the forest canopy to light penetration encouraging themassive recruitment of pioneer and nonpioneer light-de-manding species which largely survive under such envi-ronmental conditions According to Gang et al [47] pioneerand nonpioneer light demanders benefit from the increase in

Table 5 Understorey floristic diversity of life forms in the intensively and poorly managed Tectona grandis plantation

Management regimes Trees Grasses Shrubs Climbers HerbsIntensively managed 1785 10eminus4 10eminus4 1141 10eminus4

Poorlyunmanaged 1019 0800 10eminus4 0349 10eminus4

MannWhitney (U) 155 205 59 25 50Z score minus3263 minus3032 minus0987 minus2737 minus1671p value le0001 0002 0324 0006 0095

Table 6 Mean total height and diameter at breast height of Tectona grandis under intensive and poor management

Management regimes Total height (m) Diameter at breast height (cm)Intensively managed 2238plusmn 009 2799plusmn 022Poorly managed 2015plusmn 010 2298plusmn 013T 15889 20476df 22 22p value le0001 le0001plusmnstandard error of the mean

Table 7 Spearmanrsquos rank correlation matrix of Shannon Wienerrsquos diversity index (N 24)

Trees Grasses Shrubs Climbers HerbsTrees 1Grasses minus0707lowastlowast 1Shrubs 0398 minus0283 1Climbers 0305 minus0234 0128 1Herbs 0245 002 0029 0325 1lowastlowastCorrelation is significant at the 001 level (2-tailed)

Table 8 Tree density total biomass and carbon stock in intensively and poorly managed Tectona grandis plantations

Management regimes Density(treesha)

Total biomass(Mgha)

Total biomass(Mgtree)

Total carbon(Mgha)

Total CO2 equivalent(Mgha)

Intensively managed 30100plusmn 376 18980plusmn 185 063plusmn 001 9490plusmn 092 34828plusmn 339Poorlyunmanaged 35900plusmn 2144 13854plusmn 370 039plusmn 002 6927plusmn 185 25422plusmn 678t minus2664 12406 13638 12407 12407df 6 6 6 6 6p value 0037 le0001 le0001 le0001 le0001plusmnstandard error


light availability as a result of forest canopy opening fromsilvicultural operations resulting in higher regenerationcompared to an unmanaged plantation Also pruning andthinning in the intensively managed plantations reduce soilwater and nutrient competition under the canopy whichcreates optimal conditions for the recruitment of under-storey species [47 48] Furthermore the increase in lightpenetration temperature and moisture conditions createdin the forest floor as a result of canopy opening under thesesilvicultural practices create optimal conditions for thebreaking of the dormancy of the hard-coated seeds of pi-oneer and nonpioneer light-demanding species in the soilseed bank increasing the species diversity and richness[1 12 43] ough periodic weeding in the intensivelymanaged plantation may temporarily compromise under-storey vegetation characteristics negatively its interactionwith other silvicultural practices such as pruning andthinning in the intensively managed plantation createsoptimal conditions for the long-term positive effect onunderstorey vegetation [44] However in the poorly man-aged plantation the dense canopy and competing vegetationprevent light penetration into the forest floor which sup-pressed the regeneration of understorey floral species Onlythe soft leathered seeds of shade-tolerant species in the soilseed bank can generate and survive under these plantationscompared with the greater numbers of pioneer and non-pioneer light-demanding species regenerating under theintensively managed plantation [17 47] In addition thebroadleaf morphology of Tectona grandis provides enoughcanopy cover in the poorly managed plantation until latterstages of the dry season where environmental conditionsmay be unsuitable for the regeneration of understoreyspecies [4 50] ese results are also consistent with thefindings of many empirical studies that have reported thepositive response of understorey species to forest canopydisturbance through pruning and thinning and long-termsuccession and recovery of degraded forest ecosystems[4 10 47 48] Our findings also cohered with many em-pirical studies that have reported high diversity and richnessof understorey species under intensively managed Tectonagrandis plantations [51ndash53] Kyereh et al [54] also reportedthat a greater percentage of West African plant species arepioneer species that respond positively to silvicultural in-terventions which alter forest canopy characteristicsHowever in terms of life forms the intensively managedplantation supported a greater diversity of trees and climbersand low diversity of grasses whilst the poorly managedsupported a greater diversity of grasses and low diversity oftrees e higher diversity of grasses in the poorly managedcompared with the intensively managed plantation could beattributed to the prolific breeding and competitive charac-teristics of grasses compared with other life forms Com-parative studies of the understorey trees and grasses diversityin plantation forests have revealed a significant decrease intree species diversity and increase the diversity of grasses inpoorly managed plantations [55 56] According to Anguyi[55] poor management of plantations encourages the re-generation of grasses which through their competitiveadvantage suppresses the regeneration of trees and other life

forms in the understorey of plantations is presupposesthat in poorly managed plantations particularly Tectonagrandis plantation grasses become the dominant under-storey vegetation and eventually out-compete all other lifeforms resulting in the reduction in the diversity of naturallyregenerated native trees (Table 6)

42 Understorey Species Composition Similarity e studyrevealed a marginally low level of similarity among the specieson the two study sites e similarity of understorey speciescomposition between the intensively managed and poorlymanaged was 0470 (47) indicating that about 47 of theunderstorey species between the intensive and the poorlymanaged Tectona grandis plantations are similar (Table 5)issuggests that about 53 of species between the two areas arecompletely different According to Akoto et al [32] Sorensonrsquoscoefficient similarity index less than 05 indicates differentspecies compositione differences in species composition onthe two study sites could be attributed to the interactive effectsof several environmental factors that are modified by the sil-vicultural operations in the intensive compared with the poorlymanaged plantation e opening of the forest canopy as aresult of the pruning and thinning operations in the intensivelymanaged plantation increases light penetration into the forestfloor According to Poorter [57] high light penetration into theforest floor increases the competitive advantage and influencethe recruitment and survival of light-demanding species at theexpense of shade-tolerant species e reduced soil moistureand nutrient competition in the intensively managed planta-tion create suitable microenvironmental conditions readilyavailable resources and space for the recruitment of under-storey light-demanding plant species which forms a largepercentage of the soil seed bank [58] is may have con-tributed to the dissimilarities in species composition betweenthe two sites However the similar species recorded on bothstudy sites may be due to the similarity in soil seed bankcharacteristics for both study sitesis result is consistent withthe findings of Boakye [59] who reported a higher compositionof native plant species under Taungya plantations comparedwith natural and unmanaged plantation in Ghana Accordingto the author silvicultural interventions such as weedingthinning and pruning in Taungya plantations significantlyincrease the natural regeneration diversity of species in plan-tations e results are also consistent with Zhu et alrsquos results[4] who reported species composition under open canopyplantation to be 2 to 3 times higher than plantations with aclosed canopy

Two different sites had shared species compositions of046 036 and 046 for trees herbs and climbers respec-tively is suggests that the two areas had approximately54 64 and 54 dissimilarity in understorey compositionof trees herbs and climbers respectively (Table 5) edifferences in understorey species composition in both sitescould probably be due to the different silvicultural man-agement regimes Similar studies have revealed that silvi-cultural management interventions have a great influence onunderstorey species composition [55 56] Yang et al [48]also reported dissimilarities in herbaceous understorey


species composition in intensive and poorly managedmonoculture pine and spruce plantations in China How-ever the intensive and the poorly managed plantations had ashared species composition of approximately 057 (ie 57similar species) each for understorey grasses and shrubs(Table 4) suggesting similar composition of grasses andshrubs in the two sites e similar species composition ofunderstorey grasses between the intensive and the poorlymanaged Tectona grandis plantations (Sorensonrsquos index- 057) in contrast with the significantly higher diversity ofgrasses in the poorly managed (median 080) comparedwith that in the intensively managed (median 000)plantations

43 Dendrometric Parameters of 15-Year-Old Tectona grandisPlantation under Intensive and Poor Management Both themean total height (2238 plusmn 009m) and diameter at breastheight (dbh) (2799 plusmn 022) of Tectona grandis in the in-tensively managed plantation were significantly higher(ple 0001) than those in the poorly managed plantation(height 2015 plusmn 010m diameter 2298plusmn 013) (Table 8)According to Kollert and Kleine [9] despite the ability ofTectona grandis to survive under variable environmentalconditions their growth and productivity are limited underunfavorable site conditions According to the authorsappropriate site conditions and silvicultural managementpractices in plantation forests increase the productivity ofstanding trees Binkley and Fisher [60] also reported thatforest productivity is not only limited by the lack of specificrequired resources but also by the limited supply ofmultiple required resources In dense stands with closedcanopy cover the lateral and apical growth of trees isrestricted resulting in a reduction in the height and di-ameter of the standing tree Silvicultural manipulation offorest canopy through thinning of an undesirable treetherefore warrants optimum light water and nutrient useefficiency as well as the photosynthetic capacity for max-imum productivity of the standing trees [4 48 61] Alsothe increase in solar radiation reaching the forest floor as aresult of thinning and pruning operations in intensivelymanaged plantations influences the soil temperature mi-crobial activity and mineralization of organic matter whichmake nutrient readily available to standing trees [12] ismight have contributed to the higher mean height anddiameter of trees in the intensive compared with the poorlymanaged plantation is result is consistent with manystudies that have reported higher growth performance oftrees in intensive compared with that in unmanagedplantation [9 10 17 51] eg in a study conducted to assessthe impact of silvicultural management on the growthperformance of Tectona grandis in Costa Rica Kanninenet al [51] reported 30 and 12 increases in dbh andheight respectively in thinned compared with unthinnedplots after 8 years of growth Similarly in a farm level trialto influence the adoption of silvicultural managementtechniques by smallholder plantation managers Roshetkoet al [10] also reported 60 and 124 increment in dbhand tree height respectively in thinning and pruning

treatment plots compared with that in control plot after 2years According to the authors this contributed to a threetimesrsquo increase in farmersrsquo income is therefore impliesthat silvicultural practices do not only increase the growthperformance but also the value of the standing timber andlong-term productivity of plantations

44 Total Biomass and Carbon Stock of 15-Year-Old Tectonagrandis Plantation under Intensive and Poor ManagementForests have been recognized as the most significant sinksfor atmospheric carbon dioxide [62] Recent afforestationand reforestation projects therefore aim among otherthings at increasing carbon stocks of the forest to reduceglobal climate change [63] e study therefore estimatedthe total biomass and carbon stock of Tectona grandisplantations under different management regimes e studyrevealed a significantly higher (ple 0001) total biomass(18980plusmn 1846Mgha) and carbon stock (9490plusmn092MgChaequivalent to 34828plusmn 34Mg CO2eha) in the intensivelymanaged Tectona grandis plantation compared with the totalbiomass (13854plusmn 370Mgha) and carbon stock(6427plusmn 185MgCha equivalent to 25422plusmn 678MgCO2eha)in the poorly managed plantation e significantly higheraccumulation of total biomass and carbon stock of Tectonagrandis in the intensivelymanaged plantationwas expected dueto a significant increase inmean diameter and height ofTectonagrandis in the intensive compared with that in the poorlymanaged (Table 8) ese results may be due to several factorsAccording to Kollert and Kleine [8] the biomass productivityand carbon sequestration potential of plantation forests areinfluenced by a complex interaction of vegetation character-istics microclimatic conditions and silvicultural managementpractices erefore forests with high stand density and closedcanopy cover increase the competition for the limited envi-ronmental resources which impacts negatively on its biomassaccumulation and carbon sequestration potential Also narrowspacing in the high-density stands of poorly managed plan-tations reduces the lateral expansion ability of trees whichresults in reduced diameter growth and hence the total biomassof the stand However the wider spacing in the intensivelymanaged stand as a result of pruning and thinning influencedthe absorption and conversion of solar energy into biomass forthe lateral expansion of standing trees [9] Furthermore theperiodic weeding exercises in the intensively managed plan-tation reduce light water and nutrient competition fromunderstorey species and ensure maximum utilization of theseresources for biomass production is may have contributedto the higher biomass accumulation and carbon sequestrationin the intensive compared with the poorly managed plantationis implies that apart from the economic potential intensivemanagement of Tectona grandis plantations may also increasetheir long-term capacity to sequestering carbon from the at-mosphere is result is consistent with the findings of manystudies that have reported higher biomass accumulation andcarbon stocks in intensively managed plantations [9 64 65] Itis also in agreement with Ullah et al [66] and Rahman et al [2]who found mean diameter and height to have a strong positiverelationship with total biomass and total carbon stock


5 Conclusion

It could be concluded from the findings of this study thatsilvicultural management interventions have significantpositive effects on understorey floristic diversity dendro-metric parameters (height and diameter) and carbon stockof Tectona grandis monoculture plantations in the drysemideciduous ecological zone of Ghana From the studynearly all measures of diversity indicated that the intensivelymanaged Tectona grandis plantation performed significantlybetter than the poorly managed plantationis attests to thewidely held notion that silvicultural practices are importantfor enhancing understorey diversity of naturally regeneratednative species in monoculture plantations Furthermore thetotal biomass and carbon stock of Tectona grandis plantationunder the intensive silvicultural management were signifi-cantly higher than those of the poorly managed Tectonagrandis plantation Consequently rehabilitation projects indegraded forests in the dry semideciduous ecological zone ofGhana need to adopt appropriate silvicultural managementpractices to enhance stand productivity recruitment ofnative plant species and carbon sequestration In additionthe vast area of unmanaged monoculture Tectona grandisplantation needs silvicultural intervention to increase thebiodiversity conservation and carbon sequestration Nev-ertheless further studies need to consider how understoreyregeneration diversity and carbon sequestration vary acrossdifferent ecological zones seasons and soil types underTectona grandis plantations in Ghana

Data Availability

Data used to support the study will be made available fromthe corresponding author upon request

Conflicts of Interest

e authors report no conflicts of interest

Acknowledgments

We are grateful to Mr Dabo Jonathan (FORIG) for hisimmense logistical support as well as assistance in speciesidentification We also acknowledge Mr Christian KwameDuodu for his technical support and fieldwork prefinancing

References

[1] C L C Liu O Kuchma and K V Krutovsky ldquoMixed-speciesversus monocultures in plantation forestry developmentbenefits ecosystem services and perspectives for the futurerdquoGlobal Ecology and Conservation vol 15 Article ID e004192018

[2] M M Rahman M E Kabir A S M Jahir Uddin Akon andK Ando ldquoHigh carbon stocks in roadside plantations underparticipatory management in Bangladeshrdquo Global Ecologyand Conservation vol 3 pp 412ndash423 2015

[3] Y Zhang B Duan J Xian H Korpelainen and C Li ldquoLinksbetween plant diversity carbon stocks and environmentalfactors along a successional gradient in a subalpine coniferous

forest in Southwest Chinardquo Forest Ecology and Managementvol 262 no 3 pp 361ndash369 2011

[4] J Zhu D Lu and W Zhang ldquoEffects of gaps on regenerationof woody plants a meta-analysisrdquo Journal of Forestry Re-search vol 25 no 3 pp 501ndash510 2014

[5] T Fearnside G Kunstler B Courbaud and X MorinldquoManaging tree species diversity and ecosystem functionsthrough coexistence mechanismsrdquo Annals of Forest Sciencevol 75 no 3 p 65 2018

[6] J Jing K Soslashegaard W F Cong and J Eriksen ldquoSpeciesdiversity effects on productivity persistence and quality ofmultispecies swards in a four-year experimentrdquo PLoS Onevol 12 no 1 Article ID e0169208 2017

[7] FAO ldquoGlobal forest resources assessmentrdquo Main ReportFAO Forestry Paper 163 FAO Rome Italy 2010

[8] T Payn J-M Carnus P Freer-Smith et al ldquoChanges inplanted forests and future global implicationsrdquo Forest Ecologyand Management vol 352 pp 57ndash67 2015

[9] W Kollert and M Kleine Global Teak Study AnalysisEvaluation and Future Potential of Teak Resources IUFROVienna Austria 2018

[10] J M Roshetko D Rohadi A Perdana et al ldquoTeak agro-forestry systems for livelihood enhancement industrialtimber production and environmental rehabilitationrdquo For-ests Trees and Livelihoods vol 22 no 4 pp 241ndash256 2013

[11] Forestry Commission Ghana Forest Plantation StrategyForestry Commission Edinburgh UK 2016

[12] J Witzell D Bergstrom and U Bergsten ldquoVariable corridorthinningmdasha cost-effective key to provision of multiple eco-system services from young boreal conifer forestsrdquo Scandi-navian Journal of Forest Research vol 34 no 6 pp 497ndash5072019

[13] S Nilsson and W Schopfhauser ldquoe carbon-sequestrationpotential of a global afforestation programrdquo Climatic Changevol 30 no 3 pp 267ndash293 1995

[14] X Z Niu and S W Duiker ldquoCarbon sequestration potentialby afforestation of marginal agricultural land in the Mid-western USrdquo Forest Ecology and Management vol 223no 1ndash3 pp 415ndash427 2006

[15] J Kanowski C P Catterall G W Wardell-JohnsonH Proctor and T Reis ldquoDevelopment of forest structure oncleared rainforest land in eastern Australia under differentstyles of reforestationrdquo Forest Ecology and Managementvol 183 no 1ndash3 pp 265ndash280 2003

[16] C C Van L David and H Marc ldquoSimple plantations havethe potential to enhance biodiversity in degraded areas of TamDao National Park Vietnamrdquo Natural Areas Journal vol 33no 2 pp 139ndash147 2013

[17] A Duah-Gyamfi B Kyereh V K Agyeman K A Adam andK A M Swaine ldquoSeedling abundance composition andgrowth forecast under two logging intensities in a moisttropical forest in Ghanardquo Ghana Journal of Forestry vol 31pp 1ndash20 2015

[18] E Opuni-Frimpong S M Opoku A J Storer A J Burtonand D Yeboah ldquoProductivity pest tolerance and carbonsequestration of Khaya grandifoliola in the dry semi-decid-uous forest of Ghana a comparison in pure stands and mixedstandsrdquo New Forests vol 44 no 6 pp 863ndash879 2013

[19] Forestry Commission (FC) ldquoNational Forest PlantationDevelopment Programme (NFPDP)rdquo Annual Report 2012Forestry Commission Bristol UK 2012

[20] E Foli V K Agyeman and M Pentsil ldquoEnsuring sustainabletimber supply in Ghana a case for plantations of indigenous


timber speciesrdquo Technical Note No 1 p 15 Forestry ResearchInstitute of Ghana Kumasi Ghana 2009

[21] C Cossalter and C Pye-Smith Fast-wood Forestry Myths andRealitiesrsquo Forest Perspectives Center for International For-estry Research Bogor Indonesia 2003

[22] D M Nanang Plantation Forestry in Ghana Beory andApplications Nova Science Publishers Inc New York NYUSA 2012

[23] D Lamb P D Erskine and J A Parrotta ldquoRestoration ofdegraded tropical forest landscapesrdquo Science vol 310no 5754 pp 1628ndash1632 2005

[24] M Anbarashan A Padmavathy R Alexandar andN Dhatchanamoorhty ldquoSurvival growth abovegroundbiomass and carbon sequestration of mono and mixed nativetree species plantations on the Coromandel coast of IndiardquoGeology Ecology and Landscapes vol 4 no 2 pp 111ndash1202019

[25] A N Callister ldquoGenetic parameters and correlations betweenstem size forking and flowering in teak (Tectona grandis)rdquoCanadian Journal of Forest Research vol 43 no 12pp 1145ndash1150 2013

[26] A D Kokutse A D Akpene O Monteuuis A AkossouP Langbour D Guibal et al ldquoSelection of plus trees forgenetically improved teak varieties produced in Benin andTogordquo Bois amp Forets Des Tropiques vol 328 pp 55ndash66 2016

[27] D K S Goh Y Japarudin A Alwi M Lapammu A Floriand O Monteuuis ldquoGrowth differences and genetic param-eter estimates of 15 teak (Tectona grandis Lf) genotypes ofvarious ages clonally propagated by microcuttings andplanted under humid tropical conditionsrdquo Silvae Geneticavol 62 no 1ndash6 pp 196ndash206 2013

[28] A Kaosa-ard V Suangtho and E D Kjaer Experience fromTree Improvement of Teak (Tectona grandis) in BailandVol 5 Danida Forest Seed Centre Copenhagen Denmark1998

[29] E D Maynard and G S Foster Be Economics of Tree Im-provement of Teak (Tectona Grandis L) Danida Forest SeedCentre Copenhagen Denmark 1996

[30] W Kollert and L Cherubini Teak Resources and MarketAssessment 2010 FAO Planted Forests and Trees WorkingPaper Rome Italy 2012

[31] L A Ugalde Arias and O Monteuuis Teak New Trends inSilviculture Commercialization and Wood Utilization In-ternational Forestry and Agroforestry (INFOA) CartagoCosta Rica 2013

[32] S D Akoto A Asare and G Gyabaa ldquoNatural regenerationdiversity and composition of native tree species under mono-culture mixed- culture plantation and natural forestrdquo In-ternational Research Journal of Natural Sciences vol 3 no 2pp 24ndash38 2015

[33] S D Addo-Danso ldquoSurvival and growth in a moist-semideciduous forest in ghana comparison of monoculture andmixed-species plantationsrdquo Doctoral dissertation Faculty ofForest and Environmental Science Albert-Ludwigs Univer-sity Breisgau Germany 2010

[34] J B Hawthorne andM Abu-Juam Forest Protection in Ghanawith Particular Reference to Vegetation and Species e IUCNForest Conservation Programme Gland Switzerland 1995

[35] Amponsah-Kwatiah ldquoe effects of changes in rural land usepattern on agricultural development I rural Ghanardquo in A CaseStudy of Offinso DistrictKNUST Faculty of Social SciencesKumasi Ghana 1993

[36] M Gebrehiwot ldquoAssessment of natural regeneration diversityand distribution of forest tree speciesrdquo MSc thesis

International Institution for Aerospace Survey and EarthScience (ITC) Enschede Netherlands 2003

[37] W Hawthorne and N Gyakari Photoguide for the Forest Treesof Ghana TreendashSpotters Guide for Identifying the Largest TreesOxford Forestry Institute Oxford UK 2006

[38] A E MagurranMeasuring Biological Diversity John Wiley ampSons Hoboken NJ USA 2013

[39] E C Pielou An Introduction to Mathematical Ecology JohnWiley amp Sons New York NY USA 1969

[40] C J Krebs Ecology the Experimental Analysis of Distributionand Abundance e University of British Columbia Van-couver Canada 5th edition 2001

[41] A E Zanne G Lopez-Gonzalez D A Coomes et al GlobalWood Density Database Dryad 2009

[42] J Chave M Rejou-Mechain A Burquez et al ldquoImprovedallometric models to estimate the aboveground biomass oftropical treesrdquo Global Change Biology vol 20 no 10pp 3177ndash3190 2014

[43] S Kuyah J Dietz C Muthuri et al ldquoAllometric equations forestimating biomass in agricultural landscapes II Below-ground biomassrdquo Agriculture Ecosystems amp Environmentvol 158 pp 225ndash234 2012

[44] IPCC Climate Change 2014 Synthesis Report Contribution ofWorking Groups I II and III to the Fifth Assessment Report ofthe Intergovernmental Panel on Climate ChangeR K Pachauri and L A Meyer Eds IPCC Geneva Swit-zerland 2014

[45] J B Kauffman and D C Donato ldquoProtocols for the mea-surement monitoring and reporting of structure biomassand carbon stocks in mangrove forestsrdquo in Proceedings of theCIFOR Working Paper Center for International ForestResearch Bogor Indonesia 2012

[46] K A Oduro GM J Mohren M Pentildea-Claros B Kyereh andB Arts ldquoTracing forest resource development in Ghanathrough forest transition pathwaysrdquo Land Use Policy vol 48pp 63ndash72 2015

[47] Q Gang Q Yan and J Zhu ldquoEffects of thinning on early seedregeneration of two broadleaved tree species in larch plan-tations implication for converting pure larch plantations intolarch-broadleaved mixed forestsrdquo Forestry vol 88 no 5pp 573ndash585 2015

[48] B Yang X Pang B HuW Bao and G Tian ldquoDoes thinning-induced gap size result in altered soil microbial community inpine plantation in eastern Tibetan Plateaurdquo Ecology andEvolution vol 7 no 9 pp 2986ndash2993 2017

[49] T Toledo-Aceves and M D Swaine ldquoAbove- and below-ground competition between the liana Acacia kamerunensisand tree seedlings in contrasting light environmentsrdquo PlantEcology vol 196 no 2 pp 233ndash244 2008

[50] S M Opoku ldquoGrowth and productivity of Khaya grandi-foliola in the dry semi-deciduous forest of Ghana a com-parison in pure stands and in mixed standsrdquo Doctoraldissertation 2012

[51] M Kanninen D Perez MMontero and E Vıquez ldquoIntensityand timing of the first thinning of Tectona grandis plantationsin Costa Rica results of a thinning trialrdquo Forest Ecology andManagement vol 203 no 1ndash3 pp 89ndash99 2004

[52] T Keonakhone ldquoA holistic assessment of the use of teak at alandscape level in Luang Phrabang Lao PDRrdquo Doctoraldissertation Swedish University of Agricultural SciencesUppsala Sweden 2006

[53] S Fauzi ldquoVegetation composition and structure of Tectonagrandis (teak Family Verbanaceae) plantations and dry


deciduous forests in central Indiardquo Forest Ecology andManagement vol 148 no 1ndash3 pp 159ndash167 2001

[54] B Kyereh M D Swaine and J ompson ldquoEffect of light onthe germination of forest trees in Ghanardquo Journal of Ecologyvol 87 no 5 pp 772ndash783 1999

[55] A G Anguyi ldquoEffects of fire frequency on plant species di-versity and composition in queen Elizabeth national parksouthwestern Ugandardquo MSc thesis Makerere UniversityKampala Uganda 2010

[56] H Michael S Jan T Budzanani and M H Michael ldquoerelevance of fire frequency for the floodplain vegetation of theOkavango delta Botswanardquo African Journal of Ecologyvol 46 no 3 pp 350ndash358 2008

[57] L Poorter ldquoLeaf traits show different relationships with shadetolerance in moist versus dry tropical forestsrdquo New Phytol-ogist vol 181 no 4 pp 890ndash900 2009

[58] C C Kern P B Reich R A Montgomery and T F StrongldquoDo deer and shrubs override canopy gap size effects ongrowth and survival of yellow birch northern red oak easternwhite pine and eastern hemlock seedlingsrdquo Forest Ecologyand Management vol 267 pp 134ndash143 2012

[59] E A Boakye H van Gils E M Osei Jr and V N A AsareldquoDoes forest restoration using taungya foster tree speciesdiversity e case of Afram Headwaters Forest Reserve inGhanardquo African Journal of Ecology vol 50 no 3 pp 319ndash3252012

[60] D Binkley and R F Fisher Ecology and Management of ForestSoils Wiley-Blackwell Oxford UK 2013

[61] M Gspaltl W Bauerle D Binkley and H Sterba ldquoLeaf areaand light use efficiency patterns of Norway spruce underdifferent thinning regimes and age classesrdquo Forest Ecology andManagement vol 288 pp 49ndash59 2013

[62] B E Kishchuk D M Morris M Lorente et al ldquoDisturbanceintensity and dominant cover type influence rate of boreal soilcarbon change a Canadian multi-regional analysisrdquo ForestEcology and Management vol 381 pp 48ndash62 2016

[63] S S Pandey T N Maraseni and G Cockfield ldquoCarbon stockdynamics in different vegetation dominated communityforests under REDD+ a case from Nepalrdquo Forest Ecology andManagement vol 327 pp 40ndash47 2014

[64] J Garcia-Saqui ldquoGrowth rate of Tectona grandis and Cedrelaodorata in monoculture and mixed species systems in BelizeCentral Americardquo Doctoral dissertation University of Flor-ida Gainesville FL USA 2007

[65] L Nunes J Coutinho L F Nunes F Castro Rego andD Lopes ldquoGrowth soil properties and foliage chemicalanalysis comparison between pure and mixed stands ofCastanea sativa Mill and Pseudotsuga menziesii (Mirb)Franco in Northern Portugalrdquo Forest Systems vol 20 no 3pp 496ndash507 2011

[66] M R Ullah R B Gouri and B Rajib ldquoDeveloping allometricmodels for carbon stock estimation in eighteen-year-oldplantation forests of Bangladeshrdquo Jacobs Journal of Micro-biology and Pathology vol 1 no 1 p 6 2014


endorsed commercial plantations establishment as an al-ternative to ease pressure on natural forest resources [1]

Consequently vast areas of degraded forest landsglobally are being converted into plantations of different treespecies (both indigenous and exotic) in single or mixed-species stands According to Payn et al [8] the global coverof plantation forests increased from 1675 million ha in 1990to 2779 million ha in 2015 with a majority of these plan-tations being monocultures of Eucalyptus Pinus AcaciaTectona Picea and Pseudotsuga Among these plantationspecies Tectona grandis has been reported to be the mostvaluable and widely produced species globally with com-mercial plantations in about 70 tropical and subtropicalcountries in Asia Africa America and Oceania [9 10]

Plantations are thus expected to reduce the pressure onthe existing natural forests promote biodiversity conser-vation and carbon sequestration restore degraded forestsreduce soil erosion connect fragmented landscapes andprovide alternative livelihood for forest-fringe communities[1 11 12] According to Nilsson and Schopfhauser [13]plantation establishment could result in 345 million hectaresof new forests that would sequester about 15Gt of carbonper year equivalent to about 30 percent of global anthro-pogenic carbon emissions Niu and Duiker [14] also re-ported that the afforestation of marginal agricultural lands inthe Midwestern United States could offset 6ndash8 percent ofregional CO2 emissions Many studies have also reported thepotential of plantation forests for biodiversity restoration indegraded lands [15 16] However according to Kollert andKleine [9] without appropriate silvicultural interventionsthese services would be severely compromised

e situation in Ghana a sub-Saharan tropical Africancountry is not different from what persists in other coun-tries globally despite the nationrsquos well-established forestpolicies and management plans Population pressure ag-ricultural expansion bush fires unsustainable logging andmining have led to the wanton deforestation and degra-dation of approximately 80 of the primary forest coverwith associated problems such as loss of biodiversity climatechange and loss of livelihoods [11 17] As a result thegovernment of Ghana initiated the National Forest Plan-tation Development Program aimed at integrating socio-economic development and environmental sustainabilityprinciples in the restoration of degraded forest landscapesinto plantation [18] rough this initiative a total of16948976 ha of pure and mixed plantations were estab-lished in degraded forests in Ghana from 2002 to 2012 [12]However according to Foli et al [20] over 50ndash70 of theseplantations are Tectona grandis monocultures largely due toits fast growth market demand economic potential andpest and fire resistance

Despite the significant contributions of Tectonagrandis plantations to the economy of Ghana the specieshas come under serious criticism as many have raisedconcerns among others over its impacts on understoreyspecies diversity carbon stocks and soil nutrient dy-namics [1 21 22] It has also been condemned for itsnegative impact on nontimber forest products of liveli-hood importance and labeled as a threat to livelihood

sustainability in forest-fringe communities [23] How-ever many authors have argued that these negative im-pacts could be reversed through the adoption ofappropriate silvicultural practices in the management ofthese plantations [3[24] According to the authors sil-vicultural management practices such as pruning thin-ning and weeding may play a key role in enhancing theproductivity quality of wood understory diversity andcarbon sequestration potential of plantation forests

Many empirical studies in recent years have thereforegiven substantial attention to the development of modernapproaches and tools to ensure sustainable management offorest plantations Tectona grandis being the most exten-sively grown species globally has received a fair share ofcurrent forestry research attention However majority ofthese studies have largely focused on its genetic variations[25 26] growth performance [27 28] vegetative propa-gation [28] 1998) and market potential [29 30] with only afew studies exploring management techniques to enhance itsproductivity understorey floristic diversity and carbonstock [9 31]

In Ghana studies on plantations have largely focused onfloristic diversity and composition [32] productivity pesttolerance [28] and survival and growth performance [33] inmono and mixed plantations To date limited studies havefocused on the effects of different silvicultural managementtechniques on understorey floristic diversity stand pro-ductivity and carbon stocks [9 31] particularly in thewidely established Tectona grandismonoculture plantationsis study therefore seeks to assess the productivity carbonstock and understorey floristic diversity in Tectona grandisplantation under different silvicultural management regimesin the dry semideciduous ecological zone of Ghana estudy specifically examines the influence of silviculturalmanagement on (a) understorey floristic diversity(b) dendrometric parameters (height and diameter) and(c) carbon stock of Tectona grandis plantation e study isexpected to provide the necessary data to bridge the gap inknowledge on the effects of silvicultural management onfloristic diversity and carbon stock of Tectona grandisplantations It is also expected to provide the necessaryinformation for the development of strategies to improvecurrent plantation schemes for the sustainable managementof plantations

2 Materials and Methods

21 Description of the Study Area e study was conductedin the Asubima Forest Reserve in the dry semideciduousecological zone of Ghana (Figure 1) e Reserve lies withina grid reference of 74135degN 18874degW near AkumadanGhana [34] It covers a total area of 7870 hectares ereserve has a tropical monsoon climate with alternating wetand dry seasons e long-wet season starts around mid-March and ends in mid-July and is followed by a short dryseason until the end of August Its mean annual temperatureis about 26degC e reserve is a habitat of important timberspecies such as Triplochiton scleroxylon Millicia excelsEntandrophragma cylindricum and Pericopsis elata [35]






Burkina Faso

Cote drsquolvoire

Togo

0 125 25 5km

Ghana boundary



N

S

W E

644000000000 648000000000 652000000000 656000000000 660000000000 664000000000

644000000000 648000000000 652000000000 656000000000 660000000000 664000000000

7300

000

0000

073

6000

000

000

7420

000

0000

074

8000

000

000

7300

000

0000

073

6000

000

000

7420

000

0000

074

8000

000

000




1i

pi lnpi (1)


J Hprime1113868111386811138681113868

1113868111386811138681113868ln S (2)



SCSI 2c

(a + b + 2c)1113888 1113889 (3)



50m

Line transect


50m

50m 1m times 1m

10m

10m




Intensivelymanaged





AGBest 00673 times ρD2H1113872 1113873

0976 (4)




(5)



3 Results






















Table 2 Continued





4 Discussion













Total biomass(Mgha)


Total carbon(Mgha)














5 Conclusion


Data Availability




Acknowledgments


References














































































Burkina Faso

Cote drsquolvoire

Togo

0 125 25 5km

Ghana boundary



N

S

W E

644000000000 648000000000 652000000000 656000000000 660000000000 664000000000

644000000000 648000000000 652000000000 656000000000 660000000000 664000000000

7300

000

0000

073

6000

000

000

7420

000

0000

074

8000

000

000

7300

000

0000

073

6000

000

000

7420

000

0000

074

8000

000

000




1i

pi lnpi (1)


J Hprime1113868111386811138681113868

1113868111386811138681113868ln S (2)



SCSI 2c

(a + b + 2c)1113888 1113889 (3)



50m

Line transect


50m

50m 1m times 1m

10m

10m




Intensivelymanaged





AGBest 00673 times ρD2H1113872 1113873

0976 (4)




(5)



3 Results






















Table 2 Continued





4 Discussion













Total biomass(Mgha)


Total carbon(Mgha)














5 Conclusion


Data Availability




Acknowledgments


References











































































1i

pi lnpi (1)


J Hprime1113868111386811138681113868

1113868111386811138681113868ln S (2)



SCSI 2c

(a + b + 2c)1113888 1113889 (3)



50m

Line transect


50m

50m 1m times 1m

10m

10m




Intensivelymanaged





AGBest 00673 times ρD2H1113872 1113873

0976 (4)




(5)



3 Results






















Table 2 Continued





4 Discussion













Total biomass(Mgha)


Total carbon(Mgha)














5 Conclusion


Data Availability




Acknowledgments


References











































































AGBest 00673 times ρD2H1113872 1113873

0976 (4)




(5)



3 Results






















Table 2 Continued





4 Discussion













Total biomass(Mgha)


Total carbon(Mgha)














5 Conclusion


Data Availability




Acknowledgments


References
























































































Table 2 Continued





4 Discussion













Total biomass(Mgha)


Total carbon(Mgha)














5 Conclusion


Data Availability




Acknowledgments


References





















































































Table 2 Continued





4 Discussion













Total biomass(Mgha)


Total carbon(Mgha)














5 Conclusion


Data Availability




Acknowledgments


References











































































4 Discussion













Total biomass(Mgha)


Total carbon(Mgha)














5 Conclusion


Data Availability




Acknowledgments


References




















































































5 Conclusion


Data Availability




Acknowledgments


References















































































5 Conclusion


Data Availability




Acknowledgments


References










































































5 Conclusion


Data Availability




Acknowledgments


References












































































































































Documents

ComparativeAnalysisofUnderstoreyFloristicDiversityand ...downloads.hindawi.com/journals/ijfr/2020/8868824.pdf · 2020. 9. 1. · Table 2:UnderstoreyspeciesfoundintheintensivelyandpoorlymanagedTectona