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Andean forest fragmentation and the representativeness of protected natural areas in the eastern Andes, Colombia D. Armenteras*, F. Gast, H. Villareal Instituto de Investigacio ´n de Recursos Biolo ´gicos Alexander von Humboldt, Calle 37#8-40 Mezzanine, Bogota ´, Colombia Received 1 May 2002; received in revised form 20 October 2002; accepted 8 November 2002 Abstract Biodiversity characterization at the landscape level based on remote sensing and geographic information systems data has become increasingly important for conservation planning. We present the results of a study of the fragmentation of Andean forests and other ecosystems and an assessment of the representativeness at the ecosystem level of protected natural areas in the eastern Andes of Colombia. We used satellite remote sensing data to characterize ecosystems and undertook ground truthing at six sites. The 11 identified ecosystem types were analyzed within existing protected areas to assess the representativeness of these sites within the region. Five ecosystems were well-represented and six of them had < 10% of their area protected. Highland ecosystems were the best represented in protected areas due to the preponderance of highland parks in the eastern Andes. However Andean and sub Andean forests have less than 4.5 and 6.4% of their original pre-Columbian extent currently protected. Fragmentation parameters such as patch size, patch shape, number of patches, mean nearest neighbor distance and landscape shape index were also analyzed. Andean, sub Andean and dry forests are highly fragmented ecosystems but there is a clear latitudinal gradient of fragmentation. Our findings suggested that conservation efforts should be directed first toward the conservation of dry and oak forests in the center of the eastern Andes, and then Andean and sub Andean montane forests toward the south near the border with Ecuador. # 2003 Elsevier Science Ltd. All rights reserved. Keywords: Colombia; Ecosystems; Andean forest; Representativeness; Fragmentation; GIS; Protected natural areas 1. Introduction Colombia is one of the most diverse regions for flora and fauna in the world and has been identified as a megadiverse country (Chaves and Arango, 1998; Fan- din˜o and Ferreira, 1998). The loss of biodiversity and landscape transformation is occurring at such a rate that today entire ecosystem types are under threat of disappearance (Chaves and Arango, 1998). Some esti- mates suggest a current deforestation rate of 600,000 ha per year (DNP, 1994). Humans have influenced the landscape and land cover throughout the entire country. Whilst the northernmost part of the Andes presents a very complex geographical pattern of exceptional bio- logical diversity (Stattersfield et al., 1998; Myers et al., 2000) estimate that only 25% of the original tropical forest extent remains. The northern Andean, montane tropical forests (1000–3500 m.a.s.l) are currently one of the major global conservation priorities due to their biological richness, high level of endemism (Olson and Dinerstein, 1997), and also because they are considered amongst the least known ecosystems in the tropics (Stadtmu¨ller, 1987). In Colombia, Etter (1993) suggests that only 27% of this ecosystem’s original cover is left. With approxi- mately 9,000,000 ha in the Andes (Etter, 1998), 40% of which is located in the eastern slope of the eastern Andes (IavH, 1999), the Andean montane forests are also considered among the least known ecosystems in the tropics (Stadtmu¨ller, 1987). The high human popu- lation density of the Andes adds urgency to the need for the conservation of the last remnants of the Andean montane forests, a conservation priority on the national agenda (Fandin˜o and Ferreira, 1998). Traditionally the biological significance of protected areas has been evaluated by means of richness, repre- sentativeness and vulnerability analysis (Grossman et al., 1994). Initiatives such as the Gap analysis have been 0006-3207/03/$ - see front matter # 2003 Elsevier Science Ltd. All rights reserved. doi:10.1016/S0006-3207(02)00359-2 Biological Conservation 113 (2003) 245–256 www.elsevier.com/locate/biocon * Corresponding author. Tel.: +57-1-3406925; fax +57-1-2889564. E-mail address: [email protected] (D. Armenteras).

Armenteras Et Al 2003

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Andean forest fragmentation and the representativeness ofprotected natural areas in the eastern Andes, Colombia

D. Armenteras*, F. Gast, H. Villareal

Instituto de Investigacion de Recursos Biologicos Alexander von Humboldt, Calle 37#8-40 Mezzanine, Bogota, Colombia

Received 1 May 2002; received in revised form 20 October 2002; accepted 8 November 2002

Abstract

Biodiversity characterization at the landscape level based on remote sensing and geographic information systems data has

become increasingly important for conservation planning. We present the results of a study of the fragmentation of Andean forestsand other ecosystems and an assessment of the representativeness at the ecosystem level of protected natural areas in the easternAndes of Colombia. We used satellite remote sensing data to characterize ecosystems and undertook ground truthing at six sites.The 11 identified ecosystem types were analyzed within existing protected areas to assess the representativeness of these sites within

the region. Five ecosystems were well-represented and six of them had <10% of their area protected. Highland ecosystems were thebest represented in protected areas due to the preponderance of highland parks in the eastern Andes. However Andean and subAndean forests have less than 4.5 and 6.4% of their original pre-Columbian extent currently protected. Fragmentation parameters

such as patch size, patch shape, number of patches, mean nearest neighbor distance and landscape shape index were also analyzed.Andean, sub Andean and dry forests are highly fragmented ecosystems but there is a clear latitudinal gradient of fragmentation.Our findings suggested that conservation efforts should be directed first toward the conservation of dry and oak forests in the center

of the eastern Andes, and then Andean and sub Andean montane forests toward the south near the border with Ecuador.# 2003 Elsevier Science Ltd. All rights reserved.

Keywords: Colombia; Ecosystems; Andean forest; Representativeness; Fragmentation; GIS; Protected natural areas

1. Introduction

Colombia is one of the most diverse regions for floraand fauna in the world and has been identified as amegadiverse country (Chaves and Arango, 1998; Fan-dino and Ferreira, 1998). The loss of biodiversity andlandscape transformation is occurring at such a ratethat today entire ecosystem types are under threat ofdisappearance (Chaves and Arango, 1998). Some esti-mates suggest a current deforestation rate of 600,000 haper year (DNP, 1994). Humans have influenced thelandscape and land cover throughout the entire country.Whilst the northernmost part of the Andes presents avery complex geographical pattern of exceptional bio-logical diversity (Stattersfield et al., 1998; Myers et al.,2000) estimate that only 25% of the original tropicalforest extent remains. The northern Andean, montane

tropical forests (1000–3500 m.a.s.l) are currently one ofthe major global conservation priorities due to theirbiological richness, high level of endemism (Olson andDinerstein, 1997), and also because they are consideredamongst the least known ecosystems in the tropics(Stadtmuller, 1987).In Colombia, Etter (1993) suggests that only 27% ofthis ecosystem’s original cover is left. With approxi-mately 9,000,000 ha in the Andes (Etter, 1998), 40% ofwhich is located in the eastern slope of the easternAndes (IavH, 1999), the Andean montane forests arealso considered among the least known ecosystems inthe tropics (Stadtmuller, 1987). The high human popu-lation density of the Andes adds urgency to the need forthe conservation of the last remnants of the Andeanmontane forests, a conservation priority on the nationalagenda (Fandino and Ferreira, 1998).Traditionally the biological significance of protectedareas has been evaluated by means of richness, repre-sentativeness and vulnerability analysis (Grossman etal., 1994). Initiatives such as the Gap analysis have been

0006-3207/03/$ - see front matter # 2003 Elsevier Science Ltd. All rights reserved.

doi:10.1016/S0006-3207(02)00359-2

Biological Conservation 113 (2003) 245–256

www.elsevier.com/locate/biocon

* Corresponding author. Tel.: +57-1-3406925; fax +57-1-2889564.

E-mail address: [email protected] (D. Armenteras).

Page 2: Armenteras Et Al 2003

successfully implemented in temperate zones (Scott etal., 1989, 1991). First all the necessary information wascollected, then the degree in which biodiversity elementsare represented in a given conservation system wasevaluated (Jennings, 2000). This evaluation is usuallybased on information on the percentage protected ofeach type of vegetation as an estimative of its repre-sentativeness and vulnerability (Dinerstein et al., 1995;Stoms, 2000). Usually a figure of between 10 and 12%of a biodiversity element present in a protected areasystem is considered to be well-represented. This per-centage, along with the number of protected areas andtheir extension, are the most common indicators used toevaluate protected systems (McNeely and Miller, 1983;World Conservation Union, 1992; World ResourcesInstitute, 1994; Hummel, 1996; Noss, 1996; Duffy et al.,1999; Pressey et al., 2002). However, in temperate zonesmany initiatives of this kind are based on informationconcerning the distribution of all species within an area.In the tropics it is still difficult to use this kind of infor-mation due to the high number of species and the lackof knowledge of their distribution. Current tendenciesare shifting from species level evaluation towards eco-system level (Schmidt, 1996: Hughes et al., 2000)assuming that the higher the number of ecosystemsprotected, the higher the number of species preserved(Murray et al., 1997; Olson and Dinerstein, 1997; Stomset al., 1998; Noss, 1999).Ecosystem degradation, habitat loss and fragmenta-tion are among the principal causes of biodiversity lossin the world (Terborgh, 1989; Whitcom et al., 1981;Chaves and Arango, 1998; Etter, 1998). We used Geo-graphic Information Systems and Remote Sensing tech-nologies to make a first attempt toward analyzing theconservation and fragmentation state of natural ecosys-tems of the eastern Andes, an approach that has notbeen undertaken previously in this part of the country.We conducted a preliminary analysis of the representa-tiveness of natural protected areas and ecosystem frag-mentation analysis of the region to provide anassessment as to the present state of the ecosystems inthis area.We used ecosystems as an indicator of terrestrial bio-diversity following a similar approach to Powell et al.(2000) that used the Holdridge life zone system as theirindicator of the distribution of biodiversity in a pre-liminary gap analysis in Costa Rica. A similar approachhas also been used in Ecuador (Sierra et al., 2002) toassess biodiversity conservation priorities through ananalysis of ecosystem risk and representativeness.Ecosystem fragmentation, especially in forest areas,indicates a clear landscape change in regions with a highhuman presence and has been recognized as one of thecauses of biodiversity loss (Terborgh, 1989; Whitcom etal., 1981; Chaves and Arango, 1998). Furthermore, themore fragmented an ecosystem is, the higher the exposure

to land use change and human pressures is. Our aim wasto provide conservationists and environmental man-agers with information on the current state of ecosys-tems and threats to biodiversity in the eastern Andes inColombia. Our analysis includes a quantitative anddescriptive analysis of the geographic distribution, therepresentativeness in protected areas, and the fragmen-tation state of natural ecosystems in the region. Thescale used for this analysis (1:250,000) is appropriate forexamining conservation priorities in the eastern Andes.Scales between 1:250,000 and 1:500,000 are appropriateto conduct ecosystem-level priority assessments forsmall countries (or a similar extent such as the easternAndes) based on reliable risk and representativenessmeasures taking advantage of data that is available oreasily developed (Sierra et al., 2002). Based on ourresults, we propose some high-priority areas for con-servation or establishment of special managementregimes.

2. Methods

2.1. Study area

Colombia stretches through the northwestern end ofSouth America between 12�26046 N, 4�13030 S, 66�50054E and 79�02033 W. It has an area of approximately1,142,000 km2. Colombia is a topographically variablecountry. The western part is mostly mountainous as thenorthern extent of the South American Andes sub-divides into three mountain ranges when it reachesColombia. We centered our research in the easternmountain range of the Andes (the Cordillera Oriental).This region is defined as the Colombian montaneforest ecoregion following the map of Latin Americaand Caribbean ecoregions (Dinerstein et al., 1995).However, this ecoregion excludes important zones cor-responding to the Magdalena Valley montane forestsecoregion, and the eastern slopes toward the Ecuador-ian border (northern tip of the Colombian–Ecuadornorthern Andean paramo and eastern Cordillera Realmontane forest ecoregions). Thus to provide a vision ofthe eastern Andes as a whole, we extended the studyarea to include any area above 1000 m.a.s.l. on eitherside of the mountain range including the southernmostarea near the border of Ecuador. The total study areacomprised approximately 10,320,000 ha.

2.2. Ecosystems mapping

Ecosystem mapping was carried out by visual inter-pretation of false color digital satellite imagery (12Landsat TM scenes) corresponding to the followingyears: 1989, 1991, 1992, 1994 and 1996. The proceduredelineates the different dominant ecosystem categories

246 D. Armenteras et al. / Biological Conservation 113 (2003) 245–256

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based on criteria such as color, texture, and context. Wecross-referenced each area with other sources of infor-mation (e.g. refereed literature, aerial photography, fieldwork or other existing maps) (IGAC-ICA, 1987; IGAC,1983; Etter, 1998; IAvH, 1999). The labeling of theseareas with categories defined by a previously definedclassification system and adding the attributes of theinterpreted individual areas to the datasets incorporatedinto the geographic information system followed this.Andean ecosystem zonation is mainly defined by alti-tude because of its influence on temperature and oro-graphic rainfall. A number of different classificationsystems have been used in Latin America (Holdridge,Grubb, UNESCO, IUCN) with each country adoptingits own variation on one of these systems. Generally lowelevation rainforests (<900–1000 m) continue to lowermontane (2300–2100 to 1200–1000 m) and upper mon-tane (2300–2100 to 3500 m) forests. This last transitionis very important floristically because it is the upperlimit of a large number of tropical families and genera(Van der Hammen and Hooghiemstra, 2000). The alti-tudinal boundaries are location dependent with lowlandrainforest being separated from the montane forests bya 900–1000 m contour line on the west flanks of thecordillera (Doumenge et al., 1995; Gentry, 1993; Dod-son and Gentry, 1991; Forero and Gentry, 1989; Vander Hammen and Hooghiemstra, 2000) and by a 500 mcontour on the east flanks (Gentry, 1982, 1993). Thealtitudinal limits are also clearly affected by the ‘‘Mas-senerhebung’’ or mass-elevation effect, which causes theoccurrence of montane forest conditions at lower alti-tudes on narrow cordilleras and outlying ridges (Flen-ley, 1995). Sometimes a fourth altitudinal ecosystem isfound between 3000 and 3500 m: the subparamo, fol-lowed by a grass-dominated vegetation: paramo. At thehighest altitudes permanent snow and ice caps are pre-sent. At various elevations montane forests are subjectto frequent and/or persistent ground level cloud and arethus termed ‘cloud forests’.According to Hernandez (1990), a biome is defined asan assembly of ecosystems with similar structural andfunctional characteristics. The classification systemadopted in this interpretation follows the one proposedby Hernandez and Sanchez (1987) for the higher cate-gories (biomes). For the lower hierarchical categories(ecosystems), the adopted classification follows that ofthe General Map of Ecosystems of Colombia (Etter,1998). To differentiate between Andean and sub Andeanmontane forest, ecosystems that have important compo-sitional and structural difference but are difficult to dis-criminate from remote sensing data, we used GIS supportand established an artificial elevation limit of 2000 m.a.s.l.in order to separate them. Cuatrecasas (1989) indicatesthat sub Andean montane forests extend between 1000and 2400 m.a.s.l. and the Andean forests are above the2400 m.a.s.l. limit. Hernandez (1990) suggests these

limits to be around 800–1200 to 2000 m.a.s.l. for subAndean and above 2000–2400 m for Andean montaneforest. For the purpose of our study, we established thelower limit at 1000 m.a.s.l. and the limit between thetwo ecosystems types at around 2000 m.a.s.l.Any kind of landscape dominated by land uses asso-ciated with agriculture, pasture or urban sites wereassigned the category of transformed ecosystems.We used both ERDAS Imagine (ERDAS Inc., 1999)remote sensing processing software and the GIS soft-ware Arcview (ESRI, 1998) to integrate all the data. Asa result of this interpretation we obtained a map ofecosystems of the eastern mountain range at a scale of1:250,000.Ground testing was carried out in seven localities(Fig. 1). Aerial photography was used to elaboratedetailed maps of around 8000 ha for each of these sites(Fig. 2). These were used in the field to verify the satel-lite image classification.

2.3. Representativeness

Once we had produced the ecosystem map of theeastern Andes we overlaid it with a digitized map of thenational protected areas of this mountain rangeobtained from 1:100,000 to 1:200,000 scale maps (usingonly those belonging to the National Protected AreasSystem). We quantified the ecosystem composition ofthe protected areas and derived their representation ofthe coverage as a percentage figure of the total remain-ing in the study area. For paramos, Andean and subAndean forests, we also estimated the pre-transforma-tion extent from the altitudinal range and quantified itsrepresentativeness in terms of percentages of pre-trans-formation extent. For other ecosystems we consideredthat if 10% of the total area in each ecosystem wasprotected, the ecosystem was well-represented in thenational protected areas system (McNeely and Miller,1983; World Conservation Union, 1992; WorldResources Institute, 1994; Hummel, 1996; Noss, 1996).This was done with the aim of obtaining a preliminaryanalysis of representativeness of the protected area sys-tem (gap analysis) using ecosystems as indicators ofterrestrial biodiversity.

2.4. Fragmentation

Based on the ecosystem map previously obtained andwith the support of GIS, an analysis of the ecosystemfragmentation state was undertaken. The fragmentationparameters calculated for each ecosystem type were: (1)patch number (n) or number of fragments of a corre-sponding ecosystem type (>1); (2) largest patch index(LPI) or percentage of the landscape comprised by thelargest fragment of an ecosystem type (0–100%); (3) meanpatch size (MPS) or the average size of the fragments in

D. Armenteras et al. / Biological Conservation 113 (2003) 245–256 247

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an ecosystem type (>0, no limit); (4) mean nearestneighbor distance (MNND), equals the average distanceto the nearest neighboring fragment of the same eco-system type (>1) and (5) landscape shape index (LSI),the irregularity of the patch shapes (>1, no limit).The calculation of these indices was realized using thesoftware Fragstats (McGarigal and Marks, 1995). Eachone of them was chosen because of the informationprovided, and the fact that they did not include redun-dant metrics (i.e. representing the same information inan alternate way). Each index indicates one aspect of

fragmentation, the number of patches of a particularecosystem might indicate that it suffers a higher rate ofdisturbance (e.g. deforestation). Nevertheless, informa-tion on the number of patches alone does not have anyinterpretive value because it has no information aboutarea, distribution or shape of the fragments (McGarigaland Marks, 1995), for this reason this index was calcu-lated together with other metrics that could together bemore interpretable. Another example is the mean patchsize index, progressive reduction in the size of ecosystemfragments is a key component of ecosystem fragmenta-

Fig. 1. Ecosystem map, protected areas and ground truthed sites: [(1) 07�2305300N/72�2302300W, (2) 05�4101800N/73�2704700W, (3) 05�2600500N/

72�4103000W, (4) 05�3501000N / 73�2503300W, (5) 02�4705100N/74�5101800W and (6) 00�2804700N/77�1704500W)].

248 D. Armenteras et al. / Biological Conservation 113 (2003) 245–256

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tion, thus a landscape with a smaller mean patch size forthe target ecosystem than another landscape might beconsidered more fragmented (McGarigal and Marks,1995). In a similar way, the higher the mean nearestneighbor distance the higher the fragmentation of anecosystem type since the distance from a patch toanother might be increasing due to human disturbancesto that ecosystem type (e.g. deforestation, land usechange, etc.). Landscape shape index reflects the shapeand complexity of the patches, higher indices indicate

higher fragmentation equal which is due to disturbanceson the edges of an ecosystem. The study area was divi-ded into 25 � 25 km cells to allow for identification ofareas with a high degree of fragmentation. Each cell wasconsidered a landscape and the same fragmentationindices were calculated at the landscape level in order tocompare among them. A scale was established for thedegree of fragmentation for each index scaling the ori-ginal values into five classes (1, high to 5, low), and amean of all re-scaled indices was established.

Fig. 2. Classified map from aerial photography and ground truth transect in National Park Tama.

D. Armenteras et al. / Biological Conservation 113 (2003) 245–256 249

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3. Results

3.1. Ecosystem distribution

The eastern Cordillera was covered by 11 identifiednatural ecosystems, which corresponded to 49%(5,050,900 ha) of the total extension of the study area(10,320,375 ha), transformed ecosystems accounted forthe remaining 51% of the area (5,269,475 ha). The mostextensive natural ecosystems were: the sub Andean for-ests (17.4%), followed by the Andean montane forest(15.2%) and the paramos (9.5%). These ecosystemtypes, along with the oak forests (1.2%), correspond to33.8% (3,492,125 ha) of the total study area (Table 1).In terms of the forest cover, the slopes oriented towardsthe Magdalena valley in the west (between 4 and 8�300

N) are more severely transformed, although there aresome extensive remnant forest patches in the mountai-nous areas of this region.Less degraded areas were distributed throughout theeastern slopes of the mountain range especially between4� N and the border with Ecuador, and also toward thenorth around Cocuy National Park between 6� and 7� N.These areas coincide with the more isolated geographicareas where road development has been slower. However,a clear pattern of deforestation emerged in the form ofcorridors parallel to communication roads and main riv-ers. Nevertheless, forests were still distributed in a con-tinuous elevation gradient south of the eastern Andes.Ecosystems with a restricted geographic distribution(mainly due to local climate and soil conditions) such as

the Andean xerophytic scrubs (MX) (between �1200and 2600 m.a.s.l.) covered 1.25% (128,700 ha) of thestudy area. They were in specific areas of Abrego-Ocana(north of Santander); Chicamocha canyon (Boyaca);Soacha and Guatavita (Cundinamarca); Villa de Leyva(Boyaca); valleys of the rivers Guaitara, Juanambu(Narino), Guachicono (Cauca), and Cabrera (Huila).Dry forest and secondary xerophytic scrubs (BS) werefound below 1200 m.a.s.l. and occupied 3.7% of thearea (377,475 ha). This ecosystem type was also geo-graphically restricted to areas of the Chicamocha can-yon (Santander), around Cucuta (north of Santander)and in the Patıa (Cauca-Narino), Cabrera (Huila) andNegro (Cundinamarca) river valleys and to the north inthe mountainous area of Perija (Cesar-Guajira).All six sites visited for ground truthing had Andeanforests and paramos as their main ecosystems. The fieldvisit confirmed that the image classification was correctin those sites although the degree of forest fragmenta-tion that was appreciated in one of the sites from thephotographs was, in fact, higher than the impressionobtained from satellite imagery, this was mainly due tothe scale of work. The southern windows showed clearlythat the natural cover shows no sign of degradation.

3.2. Representativeness

The protected natural ecosystems of the eastern Andescover an area of 830,555 ha (8.05% of study area); 44,225ha within this area have already been transformed (over5% of the protected area) and patterns of land use

Table 1

Current coverage of natural ecosystems in the eastern Andes and percentage of protection in the system of protected areas

Natural ecosystem type

Original

area

(ha)

Current

area

(ha)

Study

area

(%)

Original

area

remaining

(%)

Protected

(ha)

Original

area

protected

(%)

Total

protected

area (%)

Current

ecosystem

area

protected

(%)

Current

ecosystem

area

unprotected

(%)

Dry forest and secondary

xerophytic shrubs (<�1200 m)*

naa

377,475 3.7 na 851 na 0.1 0.2 99.8

Xerofic shrubs of andean

localities (>�1200 m)*

na

128,700 1.2 na 0 na 0 0 100

Sub-andean montane forests

(1,000 – 2,000 m )

3,978,925

1,796,250 17.4 45% 254,125 6.4% 30.6 14.1 85.9

Andean montane forests

(2,000 – �3000–3500 m)

3,812,775

1,567,525 15.2 41% 173,550 4.5% 20.9 11.2 88.8

Humid paramos

na 920,875 8.9 na 322,075 na 38.8 35 65

Dry paramos

na 60,275 0.6 na 850 na 0.1 1.4 98.6

Superparamo

na 20,925 0.2 na 20,925 na 2.5 100 0

Snow

na 3775 0.0 na 3775 na 0.5 100 0

Oak forests

na 128,350 1.2 na 10,175 na 1.2 7.9 92.1

Intra Andean savanahs

na 29,950 0.3 na 0 na 0 0 100

Wetlands

na 16,800 0.2 na 0 na 0 0 100

Total

5,050,900 48.9 786,326 94.7

*Ecosystems with a high level of degradation.a na, Not available.

250 D. Armenteras et al. / Biological Conservation 113 (2003) 245–256

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change within the borders of some protected areas can beappreciated. The remaining 786,326 ha are natural eco-systems, equivalent to 15.6% of the existing natural eco-systems in the mountain range (4,862,925 ha). We onlyconsidered the areas above 1000 m in our calculations.In general terms, the representation objective of 10%is not met for six ecosystems. Dry and humid paramos(highland ecosystems) had a high percentage of theirarea protected with a total extent of 322,925 ha, whichequates to 36.4% of its total area within the study area(Table 1). Paramos were followed by Andean montaneforest (both Andean and sub Andean) in the degree ofprotection with 427,675 ha protected (25.3% of theexisting total). However, only 41 and 45% of these twoAndean ecosystems remain from their original extent(see Table 1) and the percentage of original pre-trans-formed protected area is 4.5% for Andean and 6.4% forsub Andean forests.In contrast, oak forests had only 7.9% of their currentsurface protected (10,175 ha) in the interior of Sanctu-aries of Flora and Fauna de Iguaque and the Guanenta-Alto Fonce river, with a total extension of 128,350 ha.Dry ecosystems were much less protected than oak for-ests. Only about 0.1% of these ecosystems were pro-tected in the Estoraques area. Over 90% of theprotected ecosystems corresponded to highland ecosys-tems and over one third of them were paramos. Withineach protected area, 9 out of 11 protected zones con-tained this ecosystem type and in five of them it con-stituted more than two thirds of their area (Table 2).Some parks had an elevation gradient, which wasreflected in the diversity and extension of the ecosys-tems, and their limits extend beyond the defined 1000m.a.s.l. lower study area limit (Cocuy, Sumapaz andTama National Parks). The remaining parks were char-acterized by the dominance of a single ecosystem.Unfortunately, and despite their legal protection status,some parks showed remarkable levels of human inter-vention that were clear from the percentage of ecosys-tems transformed found within their limits. This reflectsthe fact that a declaration of a protected area does notguarantee its protection: 7 out of 11 parks analyzedshow some degree of land use change due to humanactivities.

3.3. Fragmentation

The most fragmented ecosystems corresponded to theAndean montane forests, the sub Andean montane for-ests and the dry forests (Table 3). The Andean forestshad 118 fragments, however they had the largest patchindex of 5, meaning that a single fragment of this eco-system occupied 5% of the total of the studied area. Inthe sub Andean montane forest the number of frag-ments was 302 and the largest patch index was 3%. Themean nearest neighbor distance was similar in the

Table 2

Ecosystem composition of the 11 protected areas belonging to the

national parks system of the eastern Andes, Colombia

Protected area

Ecosystem Area

(ha)

%

LOS ESTORAQUES

Dry forest 851 100.0

PNN CHINGAZA

Humid Paramos 34,375 71.5

Subandean forest

2200 4.6

Andean forest

11,100 23.1

Transformed

375 0.8

PNN CORDILLER

LOS PICACHOS

Humid Paramos

3800 2.7

Subandean forest

119,150 84.7

Andean forest

16,200 11.5

Transformed

1575 1.1

PNN CUEVA DE

LOS GUACHAROS

Subandean forest

6050 82.3

Andean forest

1300 17.7

PNN EL COCUY

Humid Paramos 122,375 40.8

Subandean forest

73,775 24.6

Andean forest

68,625 22.9

Superparamo

20,925 7.0

Nival

3775 1.3

Transformed

10,675 3.6

PNN PISBA

Dry Paramos 20,800 58.6

Andean forest

5200 14.7

Transformed

9475 26.7

PNN SUMAPAZ

Dry Paramos 129,375 59.3

Subandean forest

22,000 10.1

Andean forest

62,275 28.6

Transformed

4350 2.0

PNN TAMA

Dry Paramos 5675 10.4

Subandean forest

27,125 49.6

Andean forest

8850 16.2

Transformed

13,050 23.9

SFF GALERAS

Dry Paramos 3125 38.6

Andean forest

3825 47.2

Transformed

1150 14.2

PNN GUANENTA

Oak Forests 7325 74.2

Humid Paramos

2550 25.8

SFF IGUAQUE

Oak Forests 2850 39.2

Dry Paramos

850 11.7

Transformed

3575 49.1

Table 3

Fragmentation indices of the eastern Andes ecosystems, Colombiaa

Ecosystem

LPI NP MPS LSI MNND

Dry forests

1.075 135 2796.1 11.749 1446.4

Xerofic shrubs

0.288 16 8043.7 10.82 15,444.4

Subandean forests

2.929 302 5947.8 18.175 1301.3

Andean forests

5.081 118 13,177.9 19.162 1602.7

Humid Paramos

4.514 40 23,021.8 14.998 6374.1

Dry Paramos

0.398 6 10,045.8 10.618 7859.6

Superparamo

0.157 3 6975 10.383 4626.9

Nival

0.026 4 943.7 10.231 926.7

Oak forests

0.426 19 6755.2 11.37 1566.8

Intra andean savanahs

0.113 4 7487.5 10.31 3177

Wetlands

0.054 7 2400 10.318 98,307.9

a LPI, largest patch index; NP, number of patches; MPS, mean

patch size; LSI, landscape shape index; MNND, mean nearest neigh-

bour distance.

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Andean and the sub Andean montane forests: 1.3 and1.6 km. There were some differences in the mean patchsize: 5947 and 13,177 ha. Dry forests also appearedfragmented, with 135 fragments, a mean patch size of2796 ha, a mean nearest neighbor distance of 1.4 kmand a largest patch index of 1.08%. Nevertheless, thisfragmentation changed over the latitudinal gradient.There were some areas dominated by a matrix of trans-formed landscapes in which dispersed fragments of theoriginal ecosystems occasionally appeared. The areabetween 4� and 8�300 N concentrated the greater num-ber of patches of Andean and sub Andean forests. Asmaller number of fragments, but with a continuous andextended presence of forest were found around theCocuy National Park and the in the south, toward theborder with Ecuador. This is why the largest patchindex values appeared to be relatively high in theseecosystems.From the results of the 25 � 25 km analysis, the 30cells with lower level of fragmentation were geo-graphically located around five protected areas: Cocuy,Pisba, Sumapaz, Tama and Picachos (Fig. 3). The restwere in the southern Andes, where there is only oneprotected area established, the Cueva de los Guacharos.This part of the eastern Andes is a very interesting areafor conservation because ecosystems are less altered,there is a clear continuous elevation gradient of forestcover toward the Amazonia (i.e. influence of Amazo-nian ecosystems and species) and high biological rich-ness (IavH, 1999).

4. Discussion

Transformed ecosystems covered 51% of the totalstudy area. The other 49% corresponded to naturalecosystems, such as paramos, and Andean and subAndean forests. These ecosystems were the best repre-sented in protected areas of the eastern Cordillera (35,14.1 and 11%, respectively). This is due to the pre-ponderance of highland parks in the Andes which ori-ginated in the establishment of Colombian protectednatural areas without organized planning. However,when incorporating criteria based only on the percen-tage of total current area of an ecosystem, we are failingto consider the important reduction dating from pre-Columbian times. If we do take this into account, thereis only a 41% and 45% of the original pre-transformedextent of Andean and sub Andean forest left and thepercentage of protected area drop to figs. of 4.5% forAndean and 6.4% for sub Andean forests. Further,despite the fact that we considered 10% of the totalcurrent area of an ecosystem as the limit to define whe-ther or not an ecosystem is well protected within thenational areas protected system, this is more a politicalconservation target than a scientifically based result

(Soule and Sanjayan, 1998). Furthermore the declara-tion of a protected area does not guarantee its protec-tion, 7 of 11 national parks analyzed show some degreeof transformation due to human activities and inter-active management practices might be needed.Despite the high level of degradation, threat of habi-tat loss and further degradation and recognized scien-tific interest, neither dry nor oak forests were properlyrepresented in the current protected areas system of theregion. We recommend that the conservation of theremaining fragments and the recovery of secondaryvegetation in these areas be made a priority. Due to thescale and approach we used in this research, only twoareas of this ecosystem were identified as high priorityfor conservation: the Soacha-Bojaca region and the areaaround the protected area Estoraques (Fig. 4). Furtherwork on a more detailed scale will allow better assess-ment of the real distribution of dry ecosystem remnantsand the degree of anthropogenic disturbance. We sug-gest further protection of oak forest areas around theSanctuaries of Flora and Fauna de Iguaque, and theGuanenta-Alto Fonce river should also be consideredhigh priority areas for conservation (Fig. 4).The area between 2� N and the border with Ecuador(Bota Caucana and Nudo de los Pastos) was also iden-tified as one with the greatest interest for conservation(Fig. 4). These areas are in a better condition, havelower degree of fragmentation and have wide elevationgradients of continuous forest cover and are not yetprotected. Consequently, conservation actions shouldbe directed toward this sector. Other identified areas ofinterest are located in areas already within the nationalpark system (Cocuy, Tama, Sumapaz and Picachosmountain range). The central region of the easternAndes has the highest degree of ecosystem alterationand the fewest remaining fragments.Some of the fragmentation values obtained in theremaining ecosystems owe more to their natural geo-graphic distribution and topographic landscape hetero-geneity than to disturbances caused by human action.This is the case for dry forests that were, to a certaindegree, naturally fragmented at this regional levelbecause they were located in specific soil and climaticconditions. Paramos and wetlands show similar restric-ted distributions. The mean neighbor distance and meanpatch size of paramos was high because of its naturallocation in the highest mountains. Dry forest frag-mented areas correspond to the Chicamocha canyon.Dry ecosystems have a high level of degradation andfragmentation that are not easy to differentiate at thisscale of research when observed from satellite images.These are only preliminary results that suggestconservation actions in specific ecosystems and areas.However, it is necessary to consider the inclusion ofother types of land management for conservationpractices outside the national parks system, such as

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indigenous territories, private reserves and forestreserves. These areas were not incorporated becauseof the scale of work we used in this study. Theincorporation of these areas in later analyses at amore detailed scale (1:100,000 or 1:25,000) will helpobtain more specific information to identify a port-

folio of sites for conservation at different geographiclevels.We also suggest redefining some of the protectedareas of the national parks system to include surround-ing areas of natural ecosystems before they are furtherdegraded, and in the mid term conduct an analysis of the

Fig. 3. The degree of fragmentation, 25 � 25 km division of the eastern Andes, Colombia and protected areas in the zone (PNN, Natural National

Park).

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effective protection level of each area. There is also aneed to clearly quantify land use change and deforesta-tion rates through a multitemporal evaluation based onremote sensing images. This multitemporal evaluation ofchange will become a valuable criterion for defining thedegree of threat to ecosystems coupled with other factorsof threat such as infrastructure and population growth.We consider this analysis an intermediate step betweenusing a coarse approach (Dinerstein et al., 1995) and a

detailed species gap analysis (Scott et al., 1991). We alsoexpect to be able to incorporate species distribution mapsto determine areas of high species richness and endemismwhen more taxonomic data becomes available.

Acknowledgements

Thanks to C. Franco for her contribution to this workand to M. Mulligan, S. Newey and the reviewers for

Fig. 4. Ecosystems and suggested areas for conservation action of the eastern Andes, Colombia.

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their comments on the manuscript. This work was par-tially supported by The Nature Conservancy and Fun-dacion Natura, Colombia.

References

Chaves, M.E., & Arango, N. (Eds.) (1998). Informe nacional sobre el

estado de la biodiversidad 1997. Instituto de Investigacion de

Recursos Biologicos Alexander von Humboldt, PNUMA and Min-

isterio de Medio Ambiente. 3 vol. Bogota, Colombia.

Cuatrecases, J., 1989. Aspectos de la vegetacion natural en Colombia.

Rev. Perez Arbelaezia. 11, 155–287. Bogota, Colombia..

Departamento Nacional de Planeacion, 1994. Polıtica ambiental.

CONPES. Presidencia de la Republica de Colombia, Bogota,

Colombia.

Dinerstein, E., Olson, D.M., Graham, D.H., Webster, A.L., Primm,

S.A., Bookbinder, M.P., Ledec, G., 1995. A Conservation Assess-

ment of the Terrestrial Ecoregions of Latin America and the Car-

ibbean. World Wildlife Fund and World Bank, Washington DC,

USA.

Dodson, C.H., Gentry, A.H., 1991. Biological extinction in western

Ecuador. Ann. Missouri Bot. Garden 78, 273–295.

Doumenge, C., Gilmour, D, Ruiz Perez, M., Blockhus, J., 1995. Tropi-

cal montane cloud forests: conervation status andmanagement issues.

In: Hamilton, L.S., Juvik, J.O., Scatena, F.N. (Eds.), Tropical

montane cloud forest. Springer-Verlag, New York, USA, pp. 24–37.

Duffy, D.C., Boggs, K., Hagenstein, R.H., Lipkin, R.y., Michaelson,

J.A., 1999. Landscape assessment of the degree of protection of

Alaska’s terrestrial biodiversity. Conservation Biology 13 (6), 1332–

1343.

Erdas Inc, 1999. Erdas Imagine Version 8.4. ERDAS, Inc, Atlanta,

Georgia, USA.

Esri Inc, 1998. Arview GIS Version 3.1. Environmental Systems

Research Institute, USA.

Etter, A., 1993. Diversidad ecosistemica en Colombia hoy. In: Carde-

nas, S., Correa, H.D. (Eds.), Nuestra Diversidad Biologica. Funda-

cion Alejandro Escobar, Coleccion Marıa Restrepo de Angel.

CEREC, Bogota, Colombia.

Etter, A., 1998. Mapa general de ecosistemas de Colombia

(1:1.500.000). In: Chaves, M.E., Arango, N. (Eds.), Informe nacio-

nal sobre el estado de la biodiversidad 1997. Instituto de Investiga-

cion de Recursos Biologicos Alexander von Humboldt, PNUMA

and Ministerio de Medio Ambiente. 3 vol, Bogota, Colombia.

Fandino, M.C., Ferreira, P. (Eds.), 1998. Colombia biodiversidad

siglo XXI: propuesta tecnica para la formulacion de un plan de

accion nacional en biodiversidad. Instituto de Investigacion de

Recursos Biologicos Alexander von Humboldt, Ministerio del

Medio Ambiente y Departamento Nacional de Planeacion, Bogota,

Colombia.

Flenley, J.R., 1995. Cloud forest, the Massenerhebung effect, and

ultraviolet insolation. In: Hamilton, L.S., Juvik, J.O., Scatena, F.N.

(Eds.), Tropical Montane Cloud Forests. Ecol. Studies (Vol. 110).

Springer-Verlag, New York, pp. 150–155.

Forero, E., Gentry, A.H., 1989. Lista anotada de las plantas del

Departamento del Choco, Colombia. Biblioteca J.J. Triana No. 10.

Instituto de Ciencias Naturales, Museo de Historia Natural, Uni-

versidad Nacional de Colombia, Bogota.

Gentry, A.H., 1982. Neotropical floristic diversity: phytogeographical

connections between Central and South America, Pleistocene cli-

matic fluctuations, or an accident of the Andean orogeny? Ann.

Missouri Bot. Garden 69, 557–593.

Gentry, A.H. 1993. Overview of the Peruvian flora. In Brako, L.,

Zarucchi, J.L., Catalogue of the flowering plants and gymnosperms

of Peru. Monogr. Syst. Bot. Missouri Bot. Garden 45: xxix–xl.

Grossman, D. H., Goodin, K.L. & Reuss, C.L. (Eds.) (1994). Rare

plant communities of the coterminous United States—an initial

survey. Prepared for the USDI Fish and Wildlife Service. The Nat-

ure Conservancy, Arlington, VA.

Hernandez, J., 1990. La selva en Colombia. In: Carrizoza, J., Her-

nandez, J. (Eds.), Selva y Futuro. El Sello Editorial, Bogota,

Colombia, pp. 28–50.

Hernandez, J., Sanchez, E., 1987. Ensayo preliminar sobre los biomas

terrestres de Colombia. In: Sanchez, E., Hernandez, J., Rueda, V.

(Eds.), Nuevos parques naturales. Instituto de Recursos Naturales

Renovables, Bogota, Colombia.

Hughes, J., Daily, G., Ehrlich, P., 2000. Conservation of insect

diversity: a habitat approach. Conservation Biology 14 (6), 1788–

1797.

Hummel, M., 1996. Protecting Canada’s endangered species: an own-

er’s manual. Key Porter, Toronto, Canada.

IavH, 1999. Caracterizacion de la biodiversidad en areas prioritarias

de la vertiente oriental de la cordillera Oriental. Instituto de Inves-

tigacion de Recursos Biologicos Alexander von Humboldt, Villa de

Leyva, Colombia.

IGAC, 1983. Bosques de Colombia (escala 1:500.000). Instituto Geo-

grafico Agustın Codazzi, Bogota, Colombia.

IGAC-ICA, 1987. Mapa de Uso actual del suelo en Colombia (escala

1:500.000). Instituto Geografico Agustın Codazzi, Instituto Colom-

biano Agropecuario, Bogota, Colombia.

Jennings, M.D., 2000. Gap analysis: concepts, methods, and recent

results. Landscape Ecology 15, 5–20.

Mcgarigal, K., Marks, B.J., 1995. Fragstats: spatial pattern analysis

program for quantifying landscape structure. Gen. Tech. Rep.

PNW-GTR-351. US Departament of Agriculture, Forest Service,

Pacific Northwest Research Station, USA, Portland, OR.

McNeely, J.A., Miller, K.R., 1983. National parks and protected

areas. UN Economic and Social Commission for Asia and the

Pacific, Bangkok.

Murray, M., Green, M., Bunting, G, Paines, J., 1997. Priorities for

biodiversity conservation in the tropics. WCMC Biodiversity Series

6. World Conservation Press, Cambridge UK.

Myers, N., Mittermeier, R.A., Mittermeier, C.G., Da Fonseca,

G.A.B., Kent, J., 2000. Biodiversity hotspots for conservation prio-

rities. Nature 403, 853–858.

Noss, R.F., 1996. In: Wright, R.G. (Ed.), National parks and pro-

tected areas: their role in environmental protection. Blackwell

Science, Cambridge, USA, pp. 91–119.

Noss, R.F., 1999. Assessing and monitoring forest biodiversity: a

suggested framework and indicators. Forest Ecology and Manage-

ment 111, 135–146.

Olson, D.M., Dinerstein, E., 1997. Global 2000: conserving the

world’s distinctive ecoregions. WWF-US, USA.

Powell, G.V.N., Barborak, J., Rodriguez, M., 2000. Assessing repre-

sentativenes of protected natural areas in Costa Rica for conserving

biodiversity: a preliminary gap analyis. Biological Conservation 93,

35–41.

Pressey, R.L., Whish, G., 2002. L, Barrett, T. W., Watts, M.E. Effec-

tivenes of protected areas in north-eastern New South Wales: recent

trends in six measures. Biological Conservation 106, 57–69.

Schmidt, K., 1996. Rare habitat vie for protection. Science 274, 916–

918.

Scott, J.M., Csuti, B., Estes, J.E., Anderson, H., 1989. State assess-

ment of biodiversity protection. Conservation Biology 3, 85–87.

Scott, J.M., Csuti, B., Estes, J.E., Caicco, S., 1991. Gap analysis of

species richness and vegetation cover: an integrated biodiverstiy

conservation strategy. In: Kohm, K. (Ed.), Balancing on the brink

of extinction: the endangered species act and lessons for the future.

Island Press, Washington DC USA, pp. 282–297.

Sierra, R., Campos, F., Chamberlin, J., 2002. Assessing biodiversity

conservation priorities: ecosystem risk and representativeness in

continental Ecuador. Landscape and Urban Planning 59, 95–110.

D. Armenteras et al. / Biological Conservation 113 (2003) 245–256 255

Page 12: Armenteras Et Al 2003

Soule, M.E., Sanjayan, M.A., 1998. Conservation targets: do they

help? Science 279, 2060–2061.

Stadtmuller, T., 1987. Cloud forests in the humid tropics: a biblio-

graphic review. Centro Agronomico Tropical de Investigacion y

Ensenanza, Turrialba, Costa Rica.

Stattersfield, A.J., Crosby, M.J, Long, A.J., Wege, D.C., 1998. Ende-

mic bird areas of the world: priorities for biodiversity conservation.

BirdLife Conservation Serires, Cambridge.

Stoms, D., 2000. Gap management status and regional indicators of

threats to biodiversity. Landscape Ecology 15, 5–20.

Stoms, D.M., Borchert, M.I., Church, R.L., 1998. A systematic process

for selecting representative research natural areas. Natural Areas

Journal 18 (4), 338.

Terborgh, J., 1989. Where have all the birds gone? Princeton Uni-

versity Press, USA, New Jersey.

Van der Hammen, T., Hooghiemstra, H., 2000. Neogene and

Quaternary history of vegetation, climate, and plant diversity in

Amazonia. Quaternary Science Reviews 19, 725–742.

Whitcom, R.F., Robbins, C.S., Lynch, J.F., 1981. Effects of forest

fragmentation on avifauna of the estern deciduous forest. In: Burgess,

R.L., Sharpe, D.M. (Eds.), Forest island dynamics in a man-domi-

nated landscapes. Springer-Verlag, New York, USA, pp. 125–205.

World Conservation Union. 1992. IUCN Bulletin 43.

World Resources Institute, 1994. World resources, 1994–1995. Oxford

University Press, New York, USA.

256 D. Armenteras et al. / Biological Conservation 113 (2003) 245–256