Effects of anthropogenic disturbance on plant diversity and community structure of a sacred grove in Meghalaya, northeast India

This study analyses the effects of anthropogenic disturbance on plant diversity and community attributes of a sacred grove (montane subtropical forest) at Swer in the East Khasi Hills district of Meghalaya in northeast India. The undisturbed, moderately disturbed and highly disturbed stands were identified within the sacred grove on the basis of canopy cover, light interception and tree (cbh 15 cm) density. The undisturbed forest stand had >40% canopy cover, >50% light interception and a density of 2103 trees per hectare, whereas the highly disturbed stand had <10% canopy cover, <10% light interception and 852 trees per hectare. The moderately disturbed stand occupied the intermediate position with respect to these parameters. The study revealed that the mild disturbance favoured species richness, but with increased degree of disturbance, as was the case in the highly disturbed stand, the species richness markedly decreased. The number of families of angiosperms was highest (63) in the undisturbed stand, followed by the moderately (60) and highly disturbed (46) stands. The families Rubiaceae, Asteraceae and Poaceae were the dominant families in the sacred forest. Rubiaceae was represented by 11, 14 and 10 species in the undisturbed, moderately disturbed and highly disturbed stands, respectively, whilst the family Asteraceae had 16 species in the moderately disturbed stand and 14 species in the highly disturbed stand. The number of families represented by a single species was reduced significantly from 33 in the undisturbed stand to 23 in the moderately and 21 in the highly disturbed stand. The similarity index was maximum (71%) between the undisturbed and moderately disturbed stand and minimum (33%) between the undisturbed and highly disturbed stands. The Margalef index, Shannon diversity index and evenness index exhibited a similar trend, with highest values in the moderately disturbed stand. In contrast, the Simpson dominance index was highest in the highly disturbed stand. There was a sharp decline in tree density and basal area from the undisturbed (2103 trees ha^–1 and 26.9 m² ha^–1) to the moderately disturbed (1268 trees ha^–1 and 18.6 m² ha^–1) and finally to the highly disturbed (852 trees ha^–1 and 7.1 m² ha^–1) stand. Density–girth curves depicted a successive reduction in number of trees in higher girth classes from the undisturbed to the moderately and highly disturbed stands. The log-normal dominance–distribution curve in the undisturbed and moderately disturbed stands indicated the complex and stable nature of the community. However, the short-hooked curve obtained for the highly disturbed stand denoted its simple and unstable nature.     

Vascular plant diversity in the sacred groves of Jaintia Hills in northeast India

Diversity of vascular plants was studied in three sacred groves of the Jaintia Hills, in northeast India. About 395 species, 250 genera, and 108 families comprising pteridophytes, gymnosperms and angiosperms were found in the groves. Orchidaceae, Rubiaceae, Asteraceae and Lauraceae were dominant families and Ficus was the largest genus, with nine species. About 160 tree species were distributed in canopy, subcanopy and under canopy strata of the forest. Concentration of tropical and temperate elements of the neighbouring Sino-Himalayan and Burma-Malayan regions, and endemic (54 species), rare (31 species) and primitive taxa (38 species) due to favourable climatic conditions and prolonged protection have contributed to the high species richness of the groves. Their better management and protection is important for the conservation of plant diversity in the region and also for the benefit of indigenous tribes of the state.     

Woody species diversity of four sacred groves in the Pondicherry region of South India

Plant wealth and diversity of four sacred groves – twoanthropogenic stands and two natural forest patches – along the southeastcoast of India adjoining Pondicherry was studied. A total of 111species, belonging to 103 genera in 53 families, were recorded from thefour sites, which together measure 15.6 ha. The number of woody species (girth at breast height(gbh) 20 cm) was 20 each in Keezbuvanagiri (KBG) andKilialamman (KLM) grove, followed by 13 in Periyakattupalayam (PKP) and 15in Periyamudaliar chavadi (PMC). Based on the important value index (IVI), PMCgrove is an association of Aglaia elaeagnoidea,Borassus flabellifer and Pterospermumsuberifolium. A two-layered forest structure resembling tropical dryevergreen forest (TDEF) was found there. Stratification was obscured in the KBGgrove, as the scrub species were abundant, indicating a scrub woodland formation.PKP and KLM were characterised by the abundance of a few species. The presenceof a stout liana of Secamone emetica (gbh 35cm), the robustness of Cretaeva magna (gbh 220cm), Syzigium cumini (gbh 207.45cm), P. suberifolium (gbh 128.7cm) and Tamarindus indica (gbh 250cm), and survival of evergreen species like A.elaeagnoidea and Pamburus missionis isbotanically significant; Polyalthia suberosa is a raretaxon found only within the groves. The persistence of the groves until thepresent time is a testimony to the sacred grove status enjoyed by them.     

Sacred groves of Manipur,northeast India:biodiversity value,status and strategies for their conservation

The people of Manipur, a state in northeast India, follow ancestral worship and animism in the form of deity worship, with the central focus on worship in forest patches. The beliefs and taboos associated with the Sylvan deities (Umanglais) in the forest patches are restricted to any sort of disturbance of flora and fauna. These social boundaries help to conserve the entire organism as a whole, which stand the concept of sacred groves. The pleasing of deities is performed every year by the Meiteis, a dominant community of Manipur, in honour of the deities and to gain their favour. Indigenous cultural and rituals practices of the local people in sacred groves serve as a tool for conserving biodiversity. Sacred groves are distributed over a wide ecosystem and help in conservation of rare and endemic species. Well-preserved sacred groves are store houses of valuable medicinal and other plants having high economic value, and serve as a refuge to threatened species. One hundred and sixty-six sacred groves were inventoried in Manipur valley that comprises Imphal east, Imphal west, Thoubal and Bishnupur districts of the state. Detailed studies were carried out in four selected sacred groves, to know the importance of biodiversity status and vegetation characteristics. A total of 173 plant species representing 145 genera under 70 families were recorded through baseline floristic survey. The species diversity indices were compared among the four studied groves. The vegetation composition and community characteristics were recorded. Ethnobotanical uses of species were examined, which reveal that 96% of the species were used as medicine for the treatment of various ailments. Utilization of herbal medicine by the Meiteis is closely related to the cultural and ritual practices. A few of the medicinal plants which have disappeared from the locality are now confined only to the groves. Socio-cultural aspects were investigated taking into account the attitudes of local people, which indicate social beliefs and taboo are eroding, simultaneously degrading the degree of protection of sacred groves. Therefore, conservation measures of sacred groves need to be formulated considering the factor of degradation and the basic necessities of the local people. Until and unless a viable option is provided to the local people (especially those who habitat nearby the adjoining areas) for sustaining their economic condition, no step for conservation of biodiversity will be successful.     

Effect of forest fragment size on tree diversity and population structure of humid subtropical forest of Meghalaya,India

The present study was conducted in subtropical humid forests of Meghalaya to study the distributional pattern of species, floristic composition, community structure and tree population structure.Forest fragments of varying sizes(0.5 ha, 1 ha, 2 ha and 5 ha) were used in the study.All of the forest fragments are distributed within the same altitudinal range, and had similar rainfall and temperature regimes.Four forest fragments were sampled using random quadrats to analyze the impact of fragment size on tree...     

Tree species diversity in small, tropical riparian forest fragments in Belize, Central America

Tree species diversity was measured in a network of very small galleryforests within the Mountain Pine Ridge savanna in Belize. Research focussed onforest patches smaller than 1 ha in size (micro-forests) and linearstrips of trees along creeks lacking interior core zones with low understoreylight levels (tree thickets). Twenty-five micro-forests and 51 tree thicketsites were sampled throughout the savanna. A total of 144 morphospecies 5cm dbh (106 in micro-forests and 117 in tree thickets) werefound, which represents 1/5 of the approximately 700 native tree species in Belize.Most (85.3%) of the species encountered are typically found in tropical rainforests and few are restricted to savanna or riparian environments. Speciesaccumulated at a much faster rate in micro-forests than in tree thickets. Onlyone species, the palm Acoelorraphe wrightii, was extremelyabundant, accounting for almost 30% of all stems. Many of the species werepresent in very low densities: 19% of all species found in micro-forests and 42%of those found in tree thickets had on average one or fewer stems per hectare. Alarge proportion of species were also found infrequently across the landscape,being present in only 36% of micro-forests and at 52% of tree thicket sites. Theresults indicate that networks of very small forest patches can contain highnumbers of species and could therefore contribute to the maintenance of regionalbiodiversity.     

云南楚雄彝族的神树林与生物多样性保护

所述的“神树林”是广泛意义上的的概念,包括多种因文化信仰面保护的各种森林块,这些森林块不仅有多种的生态功能,也是村社水平生物多样性相对集中的地方,通过对云南楚雄彝族的“神树林”进行了广泛调查,取样比较了自然保护区,村社集体林和“神树林”３种不同管理模式下的森林群落的植物物种多样性,结果表明“神树林”群落的物种总数的植物物种多样性,结果表明“神树林”群落的物种总数（６７）、样方特有种（１７）、Ｓｈａ     

Tree diversity and population structure in undisturbed and human-impacted stands of tropical wet evergreen forest in Arunachal Pradesh, Eastern Himalayas, India

Tree species richness, tree density, basal area, population structure and distribution pattern were investigated in undisturbed, mildly disturbed, moderately disturbed and highly disturbed stands of tropical wet evergreen forests of Arunachal Pradesh. The forest stands were selected based on the disturbance index (the basal area of the cut trees measured at ground level expressed as a fraction of the total basal area of all trees including felled ones): (i) undisturbed stand (0% disturbance index), (ii) mildly disturbed (20% disturbance index), (iii) moderately disturbed (40% disturbance index), and (iv) highly disturbed stand (70% disturbance index). Tree species richness varied along the disturbance gradient in different stands. The mildly disturbed stand showed the highest species richness (54 of 51 genera). Species richness was lowest (16 of 16 genera) in the highly disturbed stand. In the undisturbed stand, 47 species of 42 genera were recorded while in the moderately disturbed stand 42 species of 36 genera were found. The Shannon–Wiener diversity index for tree species ranged from 0.7 to 2.02 in all the stands. The highest tree diversity was recorded in the undisturbed stand and the lowest in the highly disturbed stand. The stands differed with respect to the tree species composition at the family and generic level. Fagaceae, Dipterocarpaceae and Clusiaceae dominated over other families and contributed 53% in the undisturbed, 51% in the mildly disturbed, 42% in the moderately disturbed and 49% in the highly disturbed forest stands to the total density of the respective stand. Stand density was highest (5452 stems ha^–1) in the undisturbed stand, followed by the mildly disturbed stand (5014), intermediate (3656) in the moderately disturbed stand and lowest (338) in the highly disturbed stand. Dominance, calculated as the importance value index of different species, varied greatly across the stands. The highest stand density and species richness were represented in the medium girth class (51–110 cm) in all the stands. In the undisturbed stand, the highest density was found in the 111–140 cm girth class, while in the mildly disturbed stand the 51–80 cm girth range recorded the highest density. About 55, 68 and 52% species were found to be regenerating in the undisturbed, mildly disturbed and moderately disturbed stands, respectively. No regeneration was recorded in the highly disturbed stand. Variation in species richness, distribution pattern and regeneration potential is related to human interference and the need for forest conservation is emphasized.     

Landscape-level tree diversity assessment in tropical forests of southern Eastern Ghats,India

This large-scale, landscape-level study aims to assess tree species diversity, stem density and stand structure of six major tropical hill forests of southern Eastern Ghats, India, namely, Bodamalai (BM), Chitteri (CH), Kalrayan (KA), Kolli hills (KO), Pachaimalai (PM) and Shervarayan hills (SH). The Eastern Ghats of India is relatively under-studied compared with the Western Ghats biodiversity hotspot. The entire stretch of southern Eastern Ghats was divided into smaller grids of 6.25 km × 6.25 km, totaling to 120 grids. Within each grid, a belt transect of 0.5 ha (5 m × 1000 m) area was laid and all trees ≥30 cm girth at breast height (gbh) were enumerated. A total of 272 tree species (≥30 cm gbh) that belonged to 181 genera and 62 families were recorded in the total 60 ha area inventoried. Diversity indices such as Shannon, Simpson and Fisher's alpha indices were 2.44, 0.03 and 42.1, respectively, for the whole 60 ha area. One way ANOVA revealed that the species richness varied significantly across the six sites (F_(5,823) = 4.854, p < 0.0002). Also, the contribution of tree species to total species richness classified by three plant types viz. evergreen, brevi-deciduous and deciduous species varied significantly across the sites (One way ANOVA: F_(2,15) = 10.05, p < 0.002). Similarity indices such as Jaccard and Sørensen showed that sites CH and KA are more similar in terms of species composition. The total stand density and basal area for the total 60 ha area were 27,412 stems (457 stems ha⁻¹) and 1012.12 m² (16.9 m² ha⁻¹), respectively. The stand density and basal area for the six sites ranged from 290 (in site BM) to 527 stems ha⁻¹ (in site KA) and from 5.6 (in site BM) to 24.4 m² ha⁻¹ (in site KO), respectively. Stand density and basal area of tree species varied significantly across the six hill complexes (F_(5,823) = 4.85, p < 0.0002 and F_(5,823) = 2.71, p < 0.02, respectively). A positive correlation was obtained between stand density and species richness in sites PM (r_s = 0.65, p < 0.05) and SH (r_s = 0.67, p < 0.05), but not in other sites. The predominant tree species in the tropical forests of southern Eastern Ghats include Albizia amara, Euphorbia antiquorum, Canthium dicoccum var. dicoccum, Memecylon edule, Chloroxylon swietenia and Nothopegia heyneana. Taxonomically, Euphorbiaceae constituted the most diverse family with 25 species. Whereas, by tree abundance the Mimosaceae with 4126 stems enumerated from the 60 ha area formed the dominant family. Bray–Curtis cluster analysis, based on tree species composition and abundance revealed that the low-diverse site BM formed a separate entity from other hill complexes. This large-scale tree diversity inventory provides a baseline data for a variety of investigations and is expected to be useful for effective forest management and biodiversity conservation of southern Eastern Ghats region.     

Biodiversity Conservation in Sacred Groves of Manipur, Northeast India: Population Structure and Regeneration Status of Woody Species

Sacred groves are forest patches conserved by the local people intertwined with their socio-cultural and religious practice. These groves harbour rich biodiversity and play a significant role in the conservation of biodiversity. Population structure and regeneration status of woody species were studied during 2001–2002 in the four sacred groves of Manipur, a state in north east India. A total of 96 woody species was recorded from the four groves, the highest being Konthoujam Lairembi sacred grove (55 species) and lowest in Heingang Marjing sacred grove having 42 species. The density–diameter distribution of woody species in the four groves showed highest stand density and species richness in the lowest girth class (30–60 cm) and decreased in the succeeding girth classes. Overall population structure of the groves based on the number of tree seedlings, saplings and adults, displayed a greater proportion of seedlings followed by saplings and adults while for the selected tree species it varied seasonally and recruitment of species increased during rainy season attaining peak during June. Regeneration status of the four sacred groves based on strength of different age groups in their population showed good regeneration. High occurrence of ‘additional species’ to the groves may be due to the invasion through dispersal from other areas. Possibly, the prevailing favourable microenvironmental conditions contributed to their establishment and growth in the groves. Absence of seedlings and saplings of some of the species in the groves may be due to their poor seed germination and establishment of seedlings in the forest.     

Comparing tree diversity and composition in coffee farms and sacred forests in the Western Ghats of India

Expansion of coffee cultivation is one of the causes of deforestation and biodiversity loss. However, shade grown coffee has been promoted as a means for preserving biodiversity in the tropics. In this study we compared tree diversity in two types of coffee management regimes with the sacred groves in the Western Ghats of India. We computed species accumulation curves, species diversity indices and evenness indices to compare the different management regimes. Results of diversity indices showed that shade coffee had less diversity compared to sacred groves. Exotic species dominated the tree diversity in lands where the tree harvesting rights are with the growers. Native trees dominated the tree diversity when growers had no ownership rights on trees. A species accumulation curve suggested that the sacred grove had higher species richness compared to other two habitats. Lack of incentive to preserve endemic species as shade trees is forcing growers to plant more exotic species in shade grown coffee plots. If encouraged, shade grown coffee can preserve some biodiversity, but cannot provide all ecological benefits of a natural forest.     

Plant biodiversity and conservation of tropical semi-evergreen forest in the Shervarayan hills of Eastern Ghats, India

Species diversity, density, population structure and dispersion patterns of all trees and lianas (30cm gbh) were inventoried in a tropical semi-evergreen forest in the Shervarayan hills of Eastern Ghats, south India. Such data are necessary for ecosystem conservation of the under-studied Eastern Ghats, as extensive forests here have already been converted to coffee and orange plantations and the landscape changed due to aluminium ore mining and quarrying. Four 1-ha plots were established in Sanyasimalai (SM) reserve forest of the Shervarayan hills, one plot (SM1) located close to mining and quarrying area, two other contiguous plots (SM2 and SM3) located in selective felling area and the fourth (SM4) in a relatively undisturbed forest. These are 1 to 4km apart in the same semi-evergreen forest tract. In the four study plots a total of 3260 stems (mean density 815ha–1) covering 80 species in 71 genera and 44 plant families were recorded. Species richness was greatest in the undisturbed plot SM4 (50), while lowest (33) in the selectively felled site SM2. The forest stand (SM4) was also denser (986 stemsha–1) and more voluminous (basal area 44.3m2ha–1 as compared with the site mean of 35m2ha–1) than the other plots. Four trees, Chionanthus paniculata, Syzygium cumini, Canthium dicoccum and Ligustrum perrottetii dominated the stand, collectively contributing to >50% of the total density. Species richness and stand density decreased with increasing tree girths. The forest stand contained a growing population, but there was considerable variation in basal area distribution between the plots. Trends in species population structure varied, particularly for selective-felled species. Most species exhibited clumped dispersion of individuals both at 0.25ha and 1-ha scales. Variation in plant diversity and abundance are related to site attributes and human impacts.     

西双版纳热带季节雨林土壤氮含量对乔木树种多样性的影响?

大气氮沉降或人类活动导致生态系统氮输入增加,可能会提高土壤氮含量水平,促进优势种的生长和减少环境异质性,从而使物种共存的生态位减少,群落物种多样性降低。为研究土壤氮含量的增加对森林群落乔木树种多样性的影响,本研究在西双版纳热带季节雨林随机设置了14个1 ha的样方,对各样方土壤总氮( TN)含量、乔木树种丰富度以及西双版纳热带季节雨林20 ha动态监测样地中各样方乔木树种及建群种望天树( Parashorea chinensis)生物量进行了调查。结果表明：土壤氮含量与乔木树种丰富度具有显著负相关而与群落及建群种望天树生物量具有显著正相关。我们推测其机制可能是：土壤氮含量增加促进了建群种望天树等的生长及群落生物量的积累,减少树种共存的生态位,由于竞争排斥等原因而导致群落树种丰富度降低。因此,减少生态系统人为氮输入,对于保护西双版纳热带季节雨林乔木树种多样性具有重要意义。     

Structure,composition and species diversity in an altitude-substrate matrix of rain forest tree communities on Mount Kinabalu,Borneo

We studied forest structure, composition and tree species diversity of eight plots in an environmental matrix of four altitudes (700, 1700, 2700 and 3100 m) and two types of geological substrates (ultrabasic and non-ultrabasic rocks) on Mount Kinabalu, Borneo. On both substrate series, forest stature, mean leaf area and tree species diversity (both 4.8 cm and 10 cm diameter at breast height [dbh]) decreased with altitude. The two forests on the different substrate series were similar at 700 m in structure, generic and familial composition and tree species diversity, but became dissimilar with increasing altitude. The decline in stature with altitude was steeper on the ultrabasic substrates than on the non-ultrabasic substrates, and tree species diversity was generally lower on ultrabasic substrates than on non-ultrabasic substrates at 1700 m. The forests on non-ultrabasic substrates at higher altitudes and those on ultrabasic substrates at the lower altitudes were similar in dbh versus tree height allometry, mean leaf area, and generic and familial composition at 1700 m. These contrasting patterns in forest structure and composition between the two substrate series suggested that altitudinal change was compressed on the ultrabasic substrates compared to the non-ultrabasic substrates. Tree species diversity was correlated with maximum tree height and estimated aboveground biomass, but was not with basal area, among the eight study sites. We suggest that forests with higher tree species diversity are characterized by greater biomass allocation to height growth relative to trunk diameter growth under more productive environment than forests with lower tree species diversity.     

Vegetation analysis and tree population structure of tropical wet evergreen forests in and around Namdapha National Park,northeast India

Species composition, diversity and tree population structure were studied in three stands of the tropical wet evergreen forest in and around Namdapha National Park, Arunachal Pradesh, India. Three study stands exposed to different intensities of disturbances were identified, viz., undisturbed (2.4 ha) in the core zone of the park, moderately disturbed (2.1 ha) in the periphery of the park and highly disturbed (2.7 ha) outside the park area. In total 200 plant species belonging to 73 families were recorded in three stands. Tree density and basal area showed a declining trend with the increase in disturbance intensity. The densities of tree saplings and seedlings were lower in the disturbed stands than in the undisturbed stand. Species like Altingia excelsa, Olea dioica, Terminalia chebula, Mesua ferrea and Shorea assamica in the undisturbed stand and Albizia procera alone in the moderately disturbed stand contributed more than 50% of the total tree density in respective stands. The undisturbed stand contained young tree population. In the highly disturbed stand, the tree density was scarce, but had uncut trees of higher girth class (>210 cm GBH). Low shrub density was recorded in both disturbed stands due to frequent human disturbances; the broken canopy and direct sunlight enhanced the abundance of herbs in these stands. With a species rarity (species having <2 individuals) of ca. 50%, the tropical wet evergreenforests of the Namdapha National Park and its adjacent areas warrant more protection from human intervention and also eco-development to meet the livelihood requirements of the local inhabitants in the peripheral areas of the Namdapha National Park in order to reduce the anthropogenic pressure on the natural resources of the park.     

Diversity and structural patterns for tropical montane and premontane forests of central Peru,with an assessment of the use of higher-taxon surrogacy

The Chanchamayo valley in the Peruvian Andes formerly contained large areas of montane and premontane tropical forests, although logging and agricultural expansion has resulted in extensive deforestation and habitat fragmentation. This study evaluates the regional context of the valley by a comparison of data from a series of one hectare plots giving data on the diversity and structure of trees ≥10 dbh, and then examines in more detail data from a 1 ha plot located in a newly declared conservation area (Pampa Hermosa Reserved Zone) embodying one of the most intact forest remains. An explicit goal was also to test the efficacy of sampling using taxonomic surrogacy, which could provide an effective means of making more efficient such work among diverse tropical forests. The Cedros de Pampa Hermosa plot contained 444 individuals belonging to 135 species, 66 genera and 35 families. The families Lauraceae, Meliaceae, Moraceae and Urticaceae provided over half of the individuals counted. The high representation of Urticaceae species suggests a disturbance regime driven by the large sizes of the Meliaceae species and their dynamics on steep slopes. Indicator species analyses supported other evidence that this site at 1,600 m is located in a broad ecotonal area transitioning to premontane and lowland rain forests. Ordinations (nMDS) based on Bray–Curtis similarities and total abundance, basal areas and presence-absence data of the 598 species (3,469 individuals) found on all seven one hectare plots sampled in the valley showed a clear separation into three tree assemblage types, namely the lower montane site, and two others on the eastern and western sides of the valley. Ordination patterns were quite similar at species and family level, but did not show any site groupings at the generic level, suggesting important turnover of species and families along environmental gradients. A number of species could not be allocated to known taxonomic groups, and were evaluated as morphotaxa. The inclusion or exclusion of such taxa did not dramatically alter the main ordination patterns within taxonomic levels of botanical family or of species, which implies that rapid inventory methods and incomplete identifications can still provide data useful for conservation planning in this and similar forests.     

Tree diversity in primary forest and different land use systems in Central Sulawesi,Indonesia

We studied the tree communities in primary forest and three different land use systems (forest gardens, ca. 5-year-old secondary forests, cacao plantations) at 900–1200 m elevation in the environs of Lore Lindu National Park, Central Sulawesi. The primary forests had ca. 150 tree species 10 cm diameter at breast height (dbh) per hectare, which is unusually high for forests at this elevation in southeast Asia. Basal area in the primary forest was 140 m² ha^–1, one of the highest values ever recorded in tropical forests worldwide. Tree species richness declined gradually from primary forest to forest gardens, secondary forests, and cacao plantations. This decline was paralleled by shifts in tree family composition, with Lauraceae, Meliaceae, and Euphorbiaceae being predominant in primary forests, Euphorbiaceae, Rubiaceae and Myristicaeae dominating in the forest gardens and Euphorbiaceae, Urticaceae, and Ulmaceae in the secondary forests. Cacao plantations were composed almost exclusively of cacao trees and two species of legume shade trees. Forest gardens further differed from primary forests by a much lower density of understorey trees, while secondary forests had fewer species of commercial interest. Comparative studies of birds and butterflies demonstrated parallel declines of species richness, showing the importance of trees in structuring tropical forest habitats and in providing resources.     

Short-term changes in tree populations in a tropical evergreen forest at Varagalaiar, Western Ghats, India

Within a 30-ha permanent plot of a tropical evergreen forest in the Anamalais, Indian Western Ghats, all the 13415 trees 30cmgbh (belonging to 153 species) were identified and tagged during 1997–1998. This communication reports the results of tree population changes based on two annual censuses (1999 and 2000) of the plot after the initial census, and compares the results with other tropical forest sites. One species, Ficus beddomei, disappeared from the plot and there was no new addition of species. Of the 96 species that showed changes in their population density, for 12 species recruitment and mortality matched. Tree recruitment (5 treesha^–1year^–1) exceeded mortality (4 treesha^–1year^–1) during the two-year period. Four modes of tree deaths were recorded in our site. The per cent mortality of trees differed between tree size classes during each recensus. The plot tree density increased progressively in the two-year period, indicating that shifts in species composition and density in natural forests, without major catastrophic disturbance, occur slowly.     

Tree form in a mixed dipterocarp forest in Indonesian Borneo

The form of tropical trees was studied with reference to the production structure of the component individuals of a tropical rain forest stand in Sebulu, East Kalimantan in Indonesian Borneo, since the production structure as a physical or bio-economical basis of tree form still remains obscure in tropical rain forests. The pipe model theory successfully explained the crown shapes of different trees, and its parameter, designated as specific pipe length, suggested an increase in the cost of leaf mass growth with an increase in crown size. A mathematical model consisting of exponential functions of aboveground height was applied for describing stem form, and its properties were examined through changes in its coefficients and by adopting an assumption of the geometrical similarity of individual stem form as a criterion for comparing differences in stem form among individual trees. Furthermore, the cost of buttersses was discussed using the relation between bole- and buttress weight calculated from the mathematical model.     

Tree and shrub diversity and abundance in fragmented littoral forest of southeastern Madagascar

In the coastal littoral forest of extreme southeastern Madagascar, westudied tree diameter at breast height (DBH) 10 cm in 20, 50× 50 m plots in each of four forest fragments, andunderstorywoody vegetation (DBH < 10 cm, 1 m tall) in60,10 × 10 m plots in three of the fragments. Oneforestfragment was located in the highly degraded Lokaro region, and three in the nearbySainte-Luce forest. Atotal of 3476 trees, representing 169 species in 55 families, were recorded inthe50 × 50 m plots, and 10282 understory stems, representing195 species in 54 families, were found in the 10 × 10m plots. For each tree, DBH was recorded. Mean tree diameter andpatterns of tree size class distribution did not differ among the four forestfragments. However, the fragments differed significantly in both tree andunderstory stem densities, species richness and diversity values, and familyrichness values, with the Lokaro fragment having the lowest values for allmeasures. Furthermore, floristic patterns, family importance values, and communitysimilarity measures revealed that the species composition at theLokaro fragment was very different from the Sainte-Luce fragments. Anthropogenicdisturbance appears most pronounced in the isolated Lokaro forest, where bioticresources are limited to this single fragment.