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ISSN 10623590, Biology Bulletin, 2011, Vol. 38, No. 10, pp. 943–949. © Pleiades Publishing, Inc., 2011. Original Russian Text © M.A. Berezutsky, 2011, published in Povolzhskii Ekologicheskii Zhurnal, 2010, No. 3, pp. 203–240. 943 INTRODUCTION Studies on adaptation of the flora to anthropogenic factors are of major interest from both theoretical and practical standpoints. The effect of these factors becomes increasingly strong and diverse with the development of civilization and the growth of global population, and the same tendency will probably be observed in the future. A drastic increase in the area of anthropogenic biotopes is a conspicuous manifesta tion of this effect. The steppe plains especially suffer from human activities, since up to 80% of their area is subject to plowing (Khmelev, 1987). This results not only in the destruction of the environment natural for plants but also in the breakage of connections unifying the components of natural complexes into an inte grated system, with consequent separation of these components and formation of isolated floras (Burda, 1990, 1994; Khmelev, 1996). Profound analysis of flora adaptation to these pro cesses is a necessary prerequisite for making a progno sis of its future development and elaborating effective measures to conserve its biological diversity. Such studies are especially relevant in view of predicted cli mate change: they may help to answer the question as to whether the intrinsic adaptive mechanisms of the flora are able to provide for the rearrangements of flo ristic complexes that are necessary under such condi tions. The processes of anthropogenic florogenesis are no less interesting in theoretical terms, since a detailed analysis of its trends and mechanisms can provide an insight into as yet unclear aspects of natural flora for mation. A number of studies have been published in the past few decades that are devoted to the floras of certain anthropogenic habitats (e.g., urban areas, technogenic biotopes, forest plantations, and agrocenoses) and provide conclusive data on the specific features of their formation (Skvortsova and Berezutsky, 2008; Infantov and Zolotukhin, 2009; etc.). However, to reveal more general trends of flora adaptation to anthropogenic impact, it is necessary to analyze floristic complexes in the entire range of anthropogenic habitats within the same area, but such studies are as yet scarce (e.g., Burda, 1991, 1998). MATERIALS AND METHODS Adaptation of the flora to the conditions of anthro pogenic habitats was studied in the southern Volga Upland (within the Saratov Region) from 1987 to 2008. For this purpose, a detailed analysis of floristic complexes was performed in all types of anthropo genic biotopes found in the region, including urban ized areas, technogenic sites, forest plantations, and agrocenoses. It should be noted that adventive species were taken into account only if they were widespread in a given habitat or entered the local flora long ago. The point is that the majority of such species initially grow in anthropogenic habitats, whereas attention in this study was focused on the invasion of adventive species into natural cenoses. In the urban flora of Saratov, species of the natural phytocenoses of areas included within the city limits during the past few decades were not taken into account. To reveal the flora specific for technogenic Adaptation of the Flora to Anthropogenic Impact in the Southern Volga Upland M. A. Berezutsky Saratov State University, Astrakhanskaya ul. 83, Saratov, 410012 Russia; email: [email protected] Received July 8, 2009 Abstract—Analysis of the flora has been performed in the main types of anthropogenic biotopes in the south of the Volga Upland (within the Saratov Region), including urbanized areas, technogenic sites, forest planta tions, and agrocenoses. The results show that only 908 out of 1379 vascular plant species listed for the study region occur in such biotopes, their number reaching a maximum of 636 in technogenic sites and decreasing to a minimum of 438 in agrocenoses. It is hypothesized that the aboriginal flora of the southern Volga Upland has a buffer capacity and will retain its basic structural pattern even if twothirds of its constituent species are lost. Keywords: flora, anthropogenic impact, adaptation, Saratov Region. DOI: 10.1134/S1062359011100013

Adaptation of the flora to anthropogenic impact in the southern Volga Upland

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ISSN 1062�3590, Biology Bulletin, 2011, Vol. 38, No. 10, pp. 943–949. © Pleiades Publishing, Inc., 2011.Original Russian Text © M.A. Berezutsky, 2011, published in Povolzhskii Ekologicheskii Zhurnal, 2010, No. 3, pp. 203–240.

943

INTRODUCTION

Studies on adaptation of the flora to anthropogenicfactors are of major interest from both theoretical andpractical standpoints. The effect of these factorsbecomes increasingly strong and diverse with thedevelopment of civilization and the growth of globalpopulation, and the same tendency will probably beobserved in the future. A drastic increase in the area ofanthropogenic biotopes is a conspicuous manifesta�tion of this effect. The steppe plains especially sufferfrom human activities, since up to 80% of their area issubject to plowing (Khmelev, 1987). This results notonly in the destruction of the environment natural forplants but also in the breakage of connections unifyingthe components of natural complexes into an inte�grated system, with consequent separation of thesecomponents and formation of isolated floras (Burda,1990, 1994; Khmelev, 1996).

Profound analysis of flora adaptation to these pro�cesses is a necessary prerequisite for making a progno�sis of its future development and elaborating effectivemeasures to conserve its biological diversity. Suchstudies are especially relevant in view of predicted cli�mate change: they may help to answer the question asto whether the intrinsic adaptive mechanisms of theflora are able to provide for the rearrangements of flo�ristic complexes that are necessary under such condi�tions. The processes of anthropogenic florogenesis areno less interesting in theoretical terms, since a detailedanalysis of its trends and mechanisms can provide aninsight into as yet unclear aspects of natural flora for�mation.

A number of studies have been published in the pastfew decades that are devoted to the floras of certainanthropogenic habitats (e.g., urban areas, technogenicbiotopes, forest plantations, and agrocenoses) andprovide conclusive data on the specific features of theirformation (Skvortsova and Berezutsky, 2008; Infantovand Zolotukhin, 2009; etc.). However, to reveal moregeneral trends of flora adaptation to anthropogenicimpact, it is necessary to analyze floristic complexes inthe entire range of anthropogenic habitats within thesame area, but such studies are as yet scarce (e.g.,Burda, 1991, 1998).

MATERIALS AND METHODS

Adaptation of the flora to the conditions of anthro�pogenic habitats was studied in the southern VolgaUpland (within the Saratov Region) from 1987 to2008. For this purpose, a detailed analysis of floristiccomplexes was performed in all types of anthropo�genic biotopes found in the region, including urban�ized areas, technogenic sites, forest plantations, andagrocenoses. It should be noted that adventive specieswere taken into account only if they were widespreadin a given habitat or entered the local flora long ago.The point is that the majority of such species initiallygrow in anthropogenic habitats, whereas attention inthis study was focused on the invasion of adventivespecies into natural cenoses.

In the urban flora of Saratov, species of the naturalphytocenoses of areas included within the city limitsduring the past few decades were not taken intoaccount. To reveal the flora specific for technogenic

Adaptation of the Flora to Anthropogenic Impactin the Southern Volga Upland

M. A. BerezutskySaratov State University, Astrakhanskaya ul. 83, Saratov, 410012 Russia;

e�mail: [email protected] July 8, 2009

Abstract—Analysis of the flora has been performed in the main types of anthropogenic biotopes in the southof the Volga Upland (within the Saratov Region), including urbanized areas, technogenic sites, forest planta�tions, and agrocenoses. The results show that only 908 out of 1379 vascular plant species listed for the studyregion occur in such biotopes, their number reaching a maximum of 636 in technogenic sites and decreasingto a minimum of 438 in agrocenoses. It is hypothesized that the aboriginal flora of the southern Volga Uplandhas a buffer capacity and will retain its basic structural pattern even if two�thirds of its constituent species arelost.

Keywords: flora, anthropogenic impact, adaptation, Saratov Region.

DOI: 10.1134/S1062359011100013

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habitats, plant communities were analyzed on theembankments of railroads and highways, pits, rockdumps, artificial ponds, dams, concrete�reinforcedbanks, etc. The category of agrocenoses included notonly farmlands proper (plowed fields, fallows,orchards, etc.) but also numerous private garden plotsin the suburbs. In the latter case, records were made ofspecies growing along the fence as well as on the plotitself.

The records were compared with the total list of theregional flora (Konspekt…, 1977–1983; Elenevskii,Radygina, and Bulanyi, 2001) to determine which ofits taxonomic and typological elements were better orworse represented in the whole set and in individualtypes of anthropogenic habitats.

RESULTS AND DISCUSSION

The flora of the southern Volga Upland includes1379 vascular plant species, and 908 of them (65.84%)were recorded in anthropogenic habitats (Table 1).The species diversity of vegetation was the highest intechnogenic sites (636 species) and the lowest in agro�cenoses (438 species). In general, dicotyledons werebetter represented in anthropogenic habitats, com�pared to monocotyledons: 69.76 vs. 54.88% of all spe�cies of the corresponding class listed in the regionalflora. The same picture was observed in each type ofsuch habitats, with the difference in this parameterbeing greater in agrocenoses and forest plantations:36.21 vs. 18.18% and 48.91 vs. 26.60%, respectively.

Analyzing the proportions of species representingthe leading families of vascular plants (Table 1), it was

found that adaptation activity in anthropogenic habi�tats was generally higher in plants of the families char�acteristic of arid areas, such as Chenopodiaceae(83.72% of all species listed in the regional flora),Lamiaceae (80.70%), and Polygonaceae (75.86%),and, in addition, Poaceae (72.95%), Brassicaceae(72.50%), Asteraceae (70.16%). This parameter wasalso high in the family Caryophyllaceae (73.85%).Conversely, low adaptation parameters were recordedfor the families Cyperaceae (38.60%) and, especially,Orchidaceae (13.04%), as could be expected.

Comparisons of adaptation parameters of eachleading families in different types of anthropogenichabitats showed that conditions in agrocenoses weremost unfavorable for all families except Caryophyl�laceae. The family Orchidaceae was absent not only inagrocenoses but also in technogenic sites. Urbanizedareas were the least suitable for Caryophyllaceae,whereas for many other families (Asteraceae, Poaceae,Fabaceae, Brassicaceae, Cyperaceae, Rosaceae,Polygonaceae) the urban environment proved to bethe optimal type of anthropogenic habitat. The familyRosaceae was equally represented in urbanized areasand in forest plantations. Conditions in the latter werefound to be most favorable for the families Caryophyl�laceae, Apiaceae, Scrophulariaceae, Boraginaceae,and Orchidaceae. The families Lamiaceae and Che�nopodiaceae showed preference for technogenic sites.

Only two among all leading families, Cyperaceaeand Orchidaceae, were represented in each type ofanthropogenic habitats by smaller percentages of spe�cies, compared to the percent representation of theregional flora as a whole. Conversely, the percent rep�

Table 1. Adaptation activity of leading vascular plant families in the set of anthropogenic habitats

FamilyNumber of species Proportion of species in an�

thropogenic habitats, %southern Volga Upland anthropogenic habitats

Asteraceae 191 134 70.16

Poaceae 122 89 72.95

Fabaceae 86 59 68.60

Brassicaceae 80 58 72.50

Caryophyllaceae 65 48 73.85

Lamiaceae 57 46 80.70

Cyperaceae 57 22 38.60

Rosaceae 54 35 64.81

Apiaceae 51 36 70.59

Scrophulariaceae 44 30 68.18

Chenopodiaceae 43 36 83.72

Boraginaceae 36 25 69.44

Ranunculaceae 34 23 67.65

Polygonaceae 29 22 75.86

Orchidaceae 23 3 13.04

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resentation of the families Asteraceae, Fabaceae, andRosaceae in individual habitat types was higher, butthey ranked only 8th, 10th, and 13th, respectively, interms of adaptation activity in the whole set of anthro�pogenic habitats. This is evidence that species of thesefamilies in the regional flora fall into two groups differ�ing in adaptation potential, Species of the first groupshave a broad adaptation potential and can occupy dif�ferent types of anthropogenic habitats, whereas thesecond group consists of euanthropophobes, i.e.,plants that cannot grow in such habitats. Other fami�lies contain smaller proportions of euanthropophobes,but species with a broad adaptation potential are alsoless numerous; i.e., certain species are more stronglyassociated with a certain type of anthropogenic habi�tats. The first group should not be completely identi�fied with ruderal species, the more so that their per�centage, e.g., in the family Chenopodiaceae is greater,but the adaptation activity of this family markedly dif�fers between the types of anthropogenic habitats: it isvery high in technogenic sites and urbanized areas butdrops below the average level for the flora as a whole inagrophytocenoses and forest plantations.

The genera of the regional flora that occupied lead�ing positions in anthropogenic habitats as a wholewere as follows: Galium (92.86% of all species repre�senting the genus in the regional flora), Vicia(83.33%), Viola (81,82%), Veronica (80.0%), Salix

(78.57%), Rumex (76.92%), Silene (73.33%), andCentaurea (72.22%) (Table 2). A lower adaptationpotential was determined for Carex (33.33%) andAstragalus (52.38%) (the largest genera in the regionalflora) and also of Allium (53.33%), Potentilla(55.55%), Euphorbia (56.25%), and Artemisia(57.89%). Among smaller genera (not included in thetable), the highest activity in colonization of anthro�pogenic habitats was demonstrated by Atriplex(100.0%), Poa (80.0%), and Plantago (70.0%), and thelowest activity, by Scorzonera (30.0%). Species of thegenera Angelica, Callitrice, Dactylorhiza, Eriophorum,Goniolimon, Helictotrichon, Orchis, Petrosimonia, andPtarmica were not recorded in anthropogenic habitats.Conversely, a group of genera were represented by100% of their constituent species listed in the regionalflora. These were Acer, Adonis, Agrostis, Alopecurus,Ambrosia, Amoria, Bidens, Bromus, Carduus, Chenop�odium, Corispermum, Cuscuta, Eleocharis, Elytrigia,Eragrostis, Erysimum, Euphrasia, Fumaria, Galeopsis,Glycyrrhiza, Gypsophila, Hieracium, Hylotelephium,Lactuca, Lamium, Melampyrum, Melica, Melilotus,Polygonum, Populus, Puccinella, Rubus, Seseli, Syre�nia, Sisymbrium, Sonchus, Spiraea, Stachys, Tarax�acum, Thalictrum, Thymus, Trifolium, Typha, Ulmus,and Verbascum.

Considering the adaptation activity of species rep�resenting the main ecocenotic groups of plants in

Table 2. Adaptation activity of leading vascular plant genera in the set of anthropogenic habitats

GenusNumber of species Proportion of species in an�

thropogenic habitats, %southern Volga Upland anthropogenic habitats

Carex 39 13 33.33

Astragalus 21 11 52.38

Artemisia 19 11 57.89

Centaurea 18 13 72.22

Potentilla 18 10 55.55

Euphorbia 16 9 56.25

Allium 15 8 53.33

Silene 15 11 73.33

Veronica 15 12 80.00

Galium 14 13 92.86

Salix 14 11 78.57

Rumex 13 10 76.92

Dianthus 12 8 66.67

Potamogeton 12 8 66.67

Vicia 12 10 83.33

Campanula 11 7 63.64

Ranunculus 11 7 63.64

Viola 11 9 81.82

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anthropogenic habitats of all types (Table 3), it wasfound that, in addition to ruderals, forest�edge specieswere most successful in colonizing these habitats(76.21% of all such species listed in the regional flora).A probable explanation is that forest�edge speciesgrow in a natural ecotone and, therefore, are superiorto species of other ecocenotic groups in terms of eco�logical tolerance and potential for adaptation to differ�ent habitat conditions. Among different types ofanthropogenic habitats, the percent representation offorest�edge species was the highest in forest planta�tions and the lowest in agrocenoses.

Steppe species also showed a relatively high adap�tation activity in anthropogenic habitats (72.11%).Such species in the southern Volga Upland grow intheir native zone, which accounts for a high level ofecological tolerance allowing them to grow success�fully under less favorable conditions of anthropogenichabitats. It is noteworthy, however, that, among alltypes of such habitats, steppe species proved to be mostnumerous in forest plantations, although it could beexpected that more xerothermic habitats (such asurbanized areas and some technogenic sites) would bemore favorable for them. Probably, such species in for�est plantations originated in many cases from frag�ments of the natural steppe that had not been plowedcompletely prior to tree planting. Therefore, the per�cent representation of steppe species in newly colo�nized secondary habitats should be lower than thatshown in Table 3.

Species characteristic of sand outcrops were wellrepresented in anthropogenic habitats (70.42%), incontrast to species from communities of limestoneoutcrops (29.03%) and noncalcareous rock outcrops

(46.15%). Among different types of such habitats, theyproved to be best represented in technogenic sites,with species characteristic of limestone outcropsoccurring almost exclusively in chalk pits. Conditionsfor the above groups in urbanized areas and agro�cenoses proved to be unfavorable, and obligate speciesof limestone outcrops were absent in these habitats.The species of sand outcrops were poorly representedin agrocenoses, and the species of noncalcareous rockoutcrops, in urbanized areas. The proportions of thesespecies in forest plantations were greater, which couldbe due to their persistence since the time before treeplanting, as in the case of steppe species. The groupcharacteristic of salinized areas was represented inanthropogenic habitats by a lower percentage of spe�cies (50.0%), compared to the regional flora as awhole, with conditions in urbanized areas and forestplantations being the most and least favorable forthem, respectively.

The species characteristic of moist and overmoist�ened habitats showed a low adaptation activity in thewhole set of anthropogenic habitats. In particular, bogspecies were absent, and the percent representation ofother ecocenotic groups was as follows: riparian spe�cies, 62.65% (slightly lower than for the regional floraas a whole); meadow species, 48.99%; and aquaticspecies, 42.22%. Meadow species were relatively wellrepresented in urbanized areas, where conditions forthem were most favorable in regularly watered lawns.

The adaptation activity of forest species in the set ofanthropogenic habitats was also relatively low(56.71%). Conditions for these species were leastfavorable in technogenic sites and most favorable inforest plantations, but their percent representation

Table 3. Adaptation activity of the main ecocenotic groups of plant species in the set of anthropogenic habitats

Ecocenotic groupNumber of species

Proportion of species in anthropogenic habitats, %

outhern Volga Upland anthropogenic habitats

Steppe species 208 150 72.11

Forest�edge species 206 157 76.21

Ruderal species 199 198 99.50

Riparian species 166 104 62.65

Forest species 164 93 56.71

Meadow species 149 73 48.99

Species of sand outcrops 71 50 70.42

Species of salinized habitats 68 34 50.00

Species of limestone outcrops 62 18 29.03

Aquatic species 45 19 42.22

Species of noncalcareous rock outcrops 26 12 46.15

Bog specie 15 0 0.0

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even in the latter case proved to be lower than that offorest�edge and steppe species.

Among species of different life forms according tothe Raunkiaer system (Table 4), phanerophytes andtherophytes were best represented in the set of anthro�pogenic habitats: 84.15 and 81.47% of all such specieslisted in the regional flora, respectively. It is notewor�thy that phanerophytes are the most sustainable bio�morph in natural habitats as well (Berezutsky, 2000):none of such species has disappeared from any localflora of the southern Volga Upland over the past cen�tury; conversely, many adventive phanerophytes haveappeared and established themselves in new biotopesduring the past few decades. This is evidence thatphanerophytes as a biomorphological group are mosttolerant to anthropogenic impact in the flora of theentire southern Volga Upland. Moreover, this fact maybe regarded as a manifestation of similarity betweenthe processes of natural and anthropogenic florogene�sis, since dominance of phanerophytes is also observedin natural floras developing under conditions of strongbiotic impact (e.g., in the moist tropical zone).

The high percent representation of therophytes inanthropogenic habitats is well explained by the factthat conditions in such habitats are unstable and,hence, unfavorable for the long�term growth of herba�

ceous species in the same area. Therefore, selectiveadvantage is gained by life forms that complete theirlife cycle within a very short period of time. A proof bycontradiction in the case is that therophytes showedthe lowest adaptation activity in forest plantations, arelatively stable type of anthropogenic habitats.Apparently, regular seed reproduction of therophytesin forest plantations is hampered due to the presenceof leaf litter, as in natural forests.

Chamaephytes showed the lowest adaptation activ�ity both in the whole set of anthropogenic habitats(46.0%) and in their individual types. A probableexplanation is that this group includes many specieswith a narrow ecological amplitude (species fromcommunities of sand, limestone, and noncalcareousrock outcrops and salinized habitats) for which condi�tions in anthropogenic habitats are unfavorable (seeabove); in addition, plants of this biomorph are vul�nerable to mechanical impact. Another noteworthyfact is that adaptation activity in anthropogenic habi�tats as a whole was higher in hemicryptophytes than incryptophytes (62.21 vs. 57.56%), and the same trendwas also observed in individual types of such habitats.Apparently, strong substrate compaction characteris�tic of anthropogenic territories has an adverse effect

Table 4. Adaptation activity of vascular plant species of different life forms (according to the Raunkiaer system) in the setof anthropogenic habitats

Life formNumber of species

Proportion of speciesin anthropogenic habitats, %

southern Volga Upland anthropogenic habitats

Phanerophytes 82 69 84.15

Chamaephytes 50 23 46.00

Hemicryptophytes 643 400 62.21

Cryptophytes 318 183 57.56

Therophytes 286 233 81.47

Table 5. Adaptation activity of vascular plant species of different life forms (according to the simplified Kazakevich–Sere�bryakov system) in anthropogenic habitats

Life formNumber of species Proportion of species

in anthropogenic habitats, %southern Volga Upland anthropogenic habitats

Trees 32 30 93.75

Shrubs 50 39 78.00

Dwarf shrubs 3 1 33.33

Semishrubs and dwarf semishrubs 45 20 44.44

Perennial herbs 884 521 58.94

Biennial herbs 79 64 81.01

Annual–biennial herbs 40 36 90.00

Annual herbs 246 197 80.08

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primarily on cryptophytes, since their vegetative budsare usually buried in the soil.

Analysis of species distribution by life formsaccording to the simplified Kazakevich–Serebryakovsystem (Table 5) revealed the following tendencies.Among phanerophytes, trees colonize anthropogenichabitats more actively, compared to shrubs (93.75 vs.78.0%). Among herbaceous species, plants with anannual or biennial life cycles showed very high adapta�tion activity in such habitats (90.00%).

The percent representation of anemophilous andentomophilous species in the set of anthropogenichabitats was almost equal: 68.47 and 66.04%, respec�tively. However, anemophilous species showed higheradaptation activity in technogenic and urbanizedareas, whereas entomophilous species were better rep�resented in forest plantations and agrophytocenoses,where the probability of pollination for them wasapparently higher than in the above two types ofanthropogenic habitats.

Many of the 908 species recorded in anthropogenichabitats occur there very rarely, probably as vestiges ofnatural cenoses. Only about 450 species are repre�sented by abundant populations in a certain type orconsistently occur in sufficient numbers in severaltypes of such habitats. The distribution of theseanthropotolerant species by elements of taxonomicand typological structure has an unexpected pattern.The percent ratio between the classes of mono� anddicotyledons (about 22 vs. 78%) is close to that in therecent flora of the southern Volga Upland. The distri�bution of aboriginal anthropotolerant species by fam�ilies basically does not differ from that in the regionalflora as a whole, except for markedly smaller propor�tion of Cyperaceae species and increased proportionsof Rosaceae, Chenopodiaceae, and Lamiaceae spe�cies. Likewise, their distribution by ecocenotic groupsalmost completely coincides with the ecocenoticstructure of the regional flora, differing only in thereduced proportion of species characteristic of lime�stone outcrops. The same is true of biomorphologicalspectra, especially when plant life forms are classifiedaccording to the Raunkiaer system (Table 6).

Analysis of these data indicates that the flora of thesouthern Volga Upland has a buffer capacity thatallows it to retain its basic structural features evenupon losing two�thirds of constituent species under

anthropogenic impact. The fact that the biomorpho�logical spectrum of plants in anthropogenic habitats isclosely similar to that of the regional flora as a wholeindicates that the pattern of their overgrowing is deter�mined mainly by macroclimatic conditions, the moreso that they remain unchanged even upon significanttransformation of all other conditions in anthropo�genic habitats. The same mechanism is known tooperate in the course of natural allochthonous floro�genesis, where plant expansion to vacant sites border�ing the overgrown land area (in our case, to anthropo�genic habitats) depends primarily on general climaticconditions (Tolmachev, 1974). Thus, the data pre�sented above suggest that the general mechanisms ofnatural and anthropogenic florogenesis are apparentlysimilar.

CONCLUSIONS

The flora of the southern Volga Upland has a goodpotential for adaptation to anthropogenic impact. Noless than two�thirds of its constituent species are capa�ble of growing in anthropogenically transformed areas.Further expansion and diversification of anthropo�genic habitats may be accompanied by an increase inthe relative number of species tolerant of anthropo�genic influences. This flora apparently has a buffercapacity with respect to these influences. The struc�tural stability of the flora in this case is accounted formainly by macroclimatic conditions. Studies on theprocesses of flora adaptation to anthropogenic habitatconditions in areas located in different natural zonesand floristic regions will show which of the tendenciesdescribed above are specific for the southern VolgaUpland or random and which of them are manifesta�tions of general trends.

REFERENCES

Berezutsky, M.A., Anthropogenic Transformation of theFlora in the Southern Volga Upland, Extended Abstract ofDoctoral (Biol.) Dissertation, Voronezh, 2000.

Burda, R.I., Cultivated Floral Isolates As a Type of Anthro�pogenic Transformation of Aboriginal Flora, in Okhrana,obogashchenie, vosproizvodstvo i ispol’zovanie rastitel’nykhresursov: Tez. dokl. (Protection, Enrichment, Reproduc�tion, and Utilization of Plant Resources: Abstr. Conf.),Stavropol: Knizhn. Izd., 1990, pp. 13–15.

Burda, R.I., Antropogennaya transformatsiya flory (Anthro�pogenic Transformation of the Flora), Kiev: NaukovaDumka, 1991.

Burda, R.I., Experience in Studies of Floral Isolates forComparing Anthropogenically Transformed Regional Flo�ras, in Aktual’nye problemy sravnitel’nogo izucheniya flor(Current Problems in Comparative Studies of Floras),St. Petersburg: Nauka, 1994, pp. 252–261.

Burda, R.I., Criteria of Adaptation to AnthropogenicImpact in Regional Floras, in Izuchenie biologicheskogo raz�noobraziya metodami sravnitel’noi floristiki (Studies of Bio�

Table 6. Distribution of species by life forms (by the Raun�kiaer system) in the flora of the southern Volga Upland

Life form Anthropotolerant species All species

Phanerophytes 5.95 8.70

Chamaephytes 3.62 2.68

Hemicryptophytes 46.63 45.53

Cryptophytes 23.06 22.99

Therophytes 20.74 20.09

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logical Diversity by Methods of Comparative Floristics),St. Petersburg: S.�Peterb. Gos. Univ., 1998, pp. 260–272.Elenevskii, A.G., Radygina, V.I., and Bulanyi, Yu.I., Opre�delitel’ sosudistykh rastenii Saratovskoi oblasti (Pra�voberezh’e Volgi) (Identification Key to Vascular Plants ofSaratov Oblast, the Right�Bank Volga Region), Moscow:Mosk. Gos. Ped. Univ., 2001.Infantov, A.A. and Zolotukhin, A.I., Synanthropization ofthe Flora in a Small City: The Example of the City of Bal�ashov, Povolzh. Ekol. Zh., 2009, no. 3, pp. 190–194.Khmelev, K.F., Plant Resources of the Central ChernozemRegion: Current State and Research Prospects, in Rasti�tel’nyi pokrov Tsentral’nogo Chernozem’ya i ego okhrana(Vegetation of the Central Chernozem Region and Its Con�servation), Voronezh: Voronezh. Gos. Univ., 1987, pp. 4–9.

Khmelev, K.F., Problems of Anthropogenic Transformationof Vegetation in the Central Chernozem Region, in Sostoy�anie i problemy ekosistem Tsentral’nogo Podon’ya (Ecosys�tems of the Central Don Region: Current State and Prob�lems), Voronezh: Voronezh. Gos. Univ., 1996, no. 6,pp. 138–143.Konspekt flory Saratovskoi oblasti (A Synopsis of the Flora ofthe Saratov Region), Chiguryaeva, A.A, Ed., Saratov: Sara�tov. Gos. Univ., 1977–1983, parts 1–4.Skvortsova, K.V. and Berezutsky, M.A., The Flora of Rail�road Embankments in the Southern Volga Uplantd, Pov�olzh. Ekol. Zh., 2008, no. 1, pp. 55–64.Tolmachev, A.I., Vvedenie v geografiyu rastenii (Introduc�tion to the Geography of Plants), Leningrad: Leningr. Gos.Univ., 1974.