Forest Restoration and Parasitoid Wasp Communities in Montane Hawai’i

Globally, most restoration efforts focus on re-creating the physical structure (flora or physical features) of a target ecosystem with the assumption that other ecosystem components will follow. Here we investigate that assumption by documenting biogeographical patterns in an important invertebrate taxon, the parasitoid wasp family Ichneumonidae, in a recently reforested Hawaiian landscape. Specifically, we test the influence of (1) planting configurations (corridors versus patches), (2) vegetation age, (3) distance from mature native forest, (4) surrounding tree cover, and (5) plant community composition on ichneumonid richness, abundance, and composition. We sampled over 7,000 wasps, 96.5% of which were not native to Hawai’i. We found greater relative richness and abundance of ichneumonids, and substantially different communities, in restored areas compared to mature forest and abandoned pasturelands. Non-native ichneumonids drive these differences; restored areas and native forest did not differ in native ichneumonid abundance. Among restored areas, ichneumonid communities did not differ by planting age or configuration. As tree cover increased within 120 m of a sampling point, ichneumonid community composition increasingly resembled that found in native forest. Similarly, native ichneumonid abundance increased with proximity to native forest. Our results suggest that restoration plantings, if situated near target forest ecosystems and in areas with higher local tree cover, can facilitate restoration of native fauna even in a highly invaded system.     

Palm species richness,abundance and diversity in the Yucatan Peninsula,in a neotropical context

Species richness, abundance and diversity patterns in palm communities in the Yucatan Peninsula were compared at three sites with different forest types (semi‐deciduous, semi‐evergreen and evergreen), as well as different precipitation, geomorphology and soil depth. All individual palms, including seedlings, juveniles and adults, were identified and counted in forty‐five (0.25 ha) transects. A total of 46 000 individual palms belonging to 11 species from nine genera and two subfamilies were recorded. Palm richness, diversity and abundance were highest in the evergreen forest. Species from the subfamily Coryphoideae dominated the semi‐deciduous and semi‐evergreen forests while species from the subfamily Arecoideae dominated the evergreen forest. Seven species were found only in the evergreen forest. Chamaedorea seifrizii and Sabal yapa were found in all three forest types, while Thrinax radiata was found in the semi‐deciduous and semi‐ evergreen forests and Cocothrinax readii only in the semi‐evergreen forest. Compared to other neotropical palm communities, the richness and diversity in the Yucatan Peninsula are lower than in the western Amazon basin. Although palm richness and diversity on the Yucatan Peninsula were positively associated with precipitation, other variables, in particular soil depth and fertility as well as habitat heterogeneity (microtopography and canopy cover), need to be considered to better understand the observed patterns.     

Impacts of forest fragmentation on orchid bee (Hymenoptera: Apidae: Euglossini) communities in the Chocó biodiversity hotspot of northwest Ecuador

Habitat loss is a major driver of bee declines worldwide, and is of key relevance in the tropics given high deforestation rates, but we continue to have a poor understanding of the impact of land-cover change on tropical bee communities. Orchid bees (Apidae: Euglossini) are critical long-distance pollinators and may be highly susceptible to forest fragmentation given their reliance on forest habitat. Previous studies on the impact of forest fragmentation on euglossines have been geographically limited, have largely ignored β-diversity, and have not compared fragments with continuous forest. To contribute to addressing these gaps, we sampled male euglossine bees in 18 forest fragments (area range: 2.5–33 ha) and at eight locations within a large (3500 ha) continuous forest in the Chocó biodiversity hotspot of Ecuador during the dry season in 2014. We assessed how euglossine abundance, richness, and evenness related to fragment area, isolation, and edge:area ratio. We also compared fragments to continuous forest, in terms of α- and β-diversity. In fragments, a single species (Euglossa tridentata) comprised 78% of captures, and we found no significant effect of fragment area, isolation, or edge on abundance, richness, or evenness among fragments. Forest fragments and continuous forest differed in both community composition and evenness, but not in abundance or species richness. Spatial turnover (β-diversity) showed a non-significant trend toward changing more rapidly in continuous forest relative to fragments. These results underscore the conservation value of continuous forest for orchid bee diversity.     

甘肃小陇山林区不同生境类型蝶类多样性研究

于2006～2008年对甘肃小陇山林区不同生境类型中蝴蝶多样性进行了调查研究,研究中依据植被的不同将该林区的蝴蝶生境划分为6种类型:人工林、灌木丛和次生林、居民农田、针阔混交林、落叶阔叶林、针叶林。共获得蝴蝶标本5365只,隶属于11科116属210种。计算了6种生境类型中蝶类物种丰富度、相似性系数和多样性指数。不同生境中,灌木丛和次生林蝶类物种的多样性指数、丰富度和个体数量较高,人工林物种多样性指数、丰富度和个体数量较低;人工林与针叶林之间的相似性系数(0.4194)最高,针阔混交林与落叶阔叶林的相似性系数(0.2951)次之,人工林与灌木丛和次生林之间的相似性系数(0.0769)最低,表明各生境之间蝶类相似性系数很低。     

Influence of Edge Exposure on Tree Seedling Species Recruitment in Tropical Rain Forest Fragments1

Edge creation has a pronounced influence on the understory vegetation, but the effects of edges on seedling species recruitment are still poorly understood. In Central Amazonia, 9–19 years after fragmentation, we recorded species richness and net seedling recruitment rate in 1 ha blocks exposed to none, one, or multiple edges within forest fragments. One‐hectare blocks were located in the center (no edge), the edge (one edge), the corners (two edges) of 10 and 100 ha fragments, and in a 1 ha fragment (four edges). In 1991, we counted all tree seedlings 5–100 cm tall found within permanent 1 m² plots located within the 1 ha blocks. In May 1993, we manually removed all seedlings that were smaller than 1 m tall from the permanent plots. Six years and five months later (October 1999), all new seedlings recruited into the plots were counted and classified into distinct morphospecies. Species richness of recruited seedlings, scaled by total seedling density, declined from the center to the edge, the corner blocks, and then to the 1 ha fragment. Overall, the four‐edged, 1 ha fragment had the poorest species richness and the non‐edged 100 ha central block the highest. The total number of recruited individuals was 40 percent less than that previously present, with the 100 ha corner having the lowest recruitment. Pairwise comparisons showed that species similarity was related to edge number for the 100 and 1 ha fragments. Species rank/abundance curves showed that a subset of species was common in all blocks within the fragments, and that the 100 ha center held more rare species than any other 1 ha block. This study demonstrated that, in a given fragment patch, the number of tree seedling species recruited varied inversely with the number of edges.     

Dung Beetle Assemblages and Seasonality in Primary Forest and Forest Fragments on Agricultural Landscapes in Budongo, Uganda

Very little is known about the diversity of arthropods in the fast-disappearing fragments of natural forests in sub-Saharan Africa. This study investigated: (1) the influence of forest fragment characteristics on dung beetle species richness, composition, abundance, and diversity; and (2) the relationship between dung beetle assemblages and rainfall pattern. Beetles were sampled through 12 mo using dung baited pitfall traps. A total of 18,073 dung beetles belonging to three subfamilies and 45 species were captured. The subfamily Scarabaeinae was the most abundant (99%) and species rich (89%). Fast-burying tunnellers (paracoprids) were the most dominant functional group. Catharsius sesostris, Copris nepos , and Heliocopris punctiventris were the three most abundant species, and had the highest contributions to dissimilarities between forests. With few exceptions, dung beetle abundance, species richness, and diversity were generally higher in larger forest fragments (100–150 ha) than in smaller ones (10–50 ha) and the nature reserve (1042 ha). Forest fragment size had a highly significant positive relationship with beetle abundance, but only when the nature reserve is excluded in the analysis. Dung beetle abundance and species richness showed direct weak relationships with litter depth (positive) and groundcover (negative) but not tree density, tree species richness, and fragment isolation distance. Dung beetle abundance and species richness were strongly correlated with monthly changes in rainfall. Results of this study indicate that forest fragments on agricultural lands in the Budongo landscape, especially medium-sized (100–150 ha) ones, represent important conservation areas for dung beetles.     

Biodiversity assessment in incomplete inventories: leaf litter ant communities in several types of Bornean rain forest

Biodiversity assessment of tropical taxa is hampered by their tremendous richness, which leads to large numbers of singletons and incomplete inventories in survey studies. Species estimators can be used for assessment of alpha diversity, but calculation of beta diversity is hampered by pseudo-turnover of species in undersampled plots. To assess the impact of unseen species, we investigated different methods, including an unbiased estimator of Shannon beta diversity that was compared to biased calculations. We studied alpha and beta diversity of a diverse ground ant assemblage from the Southeast Asian island of Borneo in different types of tropical forest: diperocarp forest, alluvial forest, limestone forest and heath forests. Forests varied in plant composition, geology, flooding regimes and other environmental parameters. We tested whether forest types differed in species composition and if species turnover was a function of the distance between plots at different spatial scales. As pseudo-turnover may bias beta diversity we hypothesized a large effect of unseen species reducing beta diversity. We sampled 206 ant species (25% singletons) from ten subfamilies and 55 genera. Diversity partitioning among the four forest types revealed that whereas alpha species richness and alpha Shannon diversity were significantly smaller than expected, beta-diversity for both measurements was significantly higher than expected by chance. This result was confirmed when we used the unbiased estimation of Shannon diversity: while alpha diversity was much higher, beta diversity differed only slightly from biased calculations. Beta diversity as measured with the Chao-Sørensen or Morisita-Horn Index correlated with distance between transects and between sample points, indicating a distance decay of similarity between communities. We conclude that habitat heterogeneity has a high influence on ant diversity and species turnover in tropical sites and that unseen species may have only little impact on calculation of Shannon beta diversity when sampling effort has been high.     

Patterns in the abundance and distribution of ichneumonid parasitoids within and across habitat patches

Abstract 1. Knowing how species are distributed across a landscape can considerably aid the management of populations and species richness. Insect parasitoids constitute a large fraction of terrestrial biodiversity and help regulate other insect populations, but their ecology is poorly known at a landscape scale. 2. Using Malaise traps distributed first extensively and then intensively across woodland patches in an agricultural landscape, we tested whether four ichneumonid subfamilies display (i) a positive relationship between abundance and occupancy, (ii) a positive relationship between abundance in the extensive sample and abundance in the intensive sample, and (iii) aggregation across traps. 3. A positive relationship between abundance and occupancy was found across species in both samples, and was relatively strong. Abundance in the extensive samples was positively correlated with abundance in the intensive samples. On average, species were aggregated in both samples, although aggregation was not necessary for a positive abundance–occupancy relationship. 4. These results suggest that ichneumonid species can largely be classified on a continuum from widespread and locally abundant to localised and locally scarce. The former species allow the potential for pervasive natural control of host populations. The latter species, which constitute a substantial majority of the species list, will be vulnerable to extinction through both stochastic forces and widespread adverse forces such as climate change and habitat modification. However, the assessment of species’ status is likely to be facilitated by the positive abundance–occupancy relationship. 5. Species inventories for ichneumonids will be taxing because of the need to sample both intensively and extensively to detect rare species, which constitute the majority of species. However, it is possible to generalise species abundances across spatial scales and years, facilitating monitoring.     

Diversity and altitudinal distribution of Chrysomelidae (Coleoptera) in Peregrina Canyon,Tamaulipas, Mexico

The Chrysomelidae (Coleoptera) is a highly speciose family that has been poorly studied at the regional level in Mexico. In the present study, we estimated species richness and diversity in oak-pine forest, Tamaulipan thorny scrub and in tropical deciduous forests in Peregrina Canyon within the Altas Cumbres Protected Area of the northeastern state of Tamaulipas, Mexico. Sampling of Chrysomelidae consisted of five sweep net samples (200 net sweeps) within each of three sites during four sample periods: early dry season, late dry season, early wet season, and late wet season. Species were identified and total numbers per species were recorded for each sample. A total of 2,226 specimens were collected belonging to six subfamilies, 81 genera and 157 species of Chrysomelidae from the study area. Galerucinae was the most abundant subfamily with 1,828 specimens, representing 82.1% of total abundance in the study area. Lower abundance was recorded in Cassidinae (8.5%), Eumolpinae (3.6%), Cryptocephalinae (2.2%), Chrysomelinae (2.2%), and finally Criocerinae (1.3%). The highest species richness was also presented in the subfamily Galerucinae with 49% of the total obtained species followed by Cassidinae (20%), Cryptocephalinae (9.7%), Eumolpinae (9.7%), Chrysomelinae (6.5%) and Criocerinae (5.2%). The most common species were Centralaphthona fulvipennis Jacoby (412 individuals), Centralaphthona diversa (Baly) (248), Margaridisa sp.1 (219), Acallepitrix sp.1 (134), Longitarsus sp.1 (104), Heterispa vinula (Erichson) (91), Epitrix sp.1 (84) and Chaetocnema sp.1 (72). Twenty-two species were doubletons (1.97% of total abundance) and 52 were singletons (2.33%). The estimated overall density value obtained was 0.0037 individuals/m2. The greatest abundance and density of individuals were recorded at the lowest elevation site. However, alpha diversity increased with increasing altitude. Similarity values were less than 50% among the three sites indicating that each site had distinct species assemblages of Chrysomelidae. The highest abundance was obtained during the late dry season, whereas diversity indices were highest during the early wet season. The present work represents the first report of the altitudinal variation in richness, abundance, and diversity of Chrysomelidae in Mexico. These results highlight the importance of conservation of this heterogeneous habitat and establish baseline data for Chrysomelidae richness and diversity for the region.     

西双版纳片段化石灰岩森林附生兰科植物多样性研究

西双版纳石灰岩地区拥有丰富的兰科植物资源,但近年来随着橡胶树的大面积种植,使得该地区很多石灰岩森林呈片段化。为了解片段化石灰岩森林中附生兰科植物多样性状况以及片段化对附生兰科植物的影响,该研究选取了生境片段化的青岩寨和曼纳览,以及连续生境的绿石林和巴卡新寨等4个样地的29个样方进行多样性调查和对比研究。结果表明:4个石灰岩森林样共记录到附生兰科植物34属76种1 528株(丛)。通过对坡向、坡度、海拔、地形、郁闭度和森林类型等6个环境因子与附生兰科植物丰富度进行CCA分析,发现石灰岩地区附生兰科植物的分布主要受海拔和森林类型2个因素的影响,在海拔较高的青岩寨和巴卡新寨附生兰科植物物种丰富度高于低海拔的绿石林和曼纳览,而片段化对附生兰科植物的物种多样性和多度均无显著影响,这可能与片段化的历史较短有关。虽然目前来看生境片段化对石灰岩地区的附生兰科植物多样性无显著影响,但生境脆弱的石灰岩森林植被的保护对于兰科植物多样性保护则更具重要性。     

Does microhabitat influence the testate amoebae communities in the Nameri National Park,northeastern India? A tropical forest perspective

The community structure of testate amoebae inhabiting different microhabitats (soil and tree-moss) within a tropical forest biome in Nameri National Park, northeastern India, was investigated. A total of 33 testate amoebae species belonging to 13 genera were identified. Species belonging to the class Lobosea constituted 73% of total testate amoebae density in the soil habitat, whereas the class Filosea constituted the most dominant forms (58%) in the moist tree-moss habitat. The relative abundance of species was higher in the tree-moss habitat compared to the soil habitats of the forest. Although multivariate analysis suggested a significant difference in assemblage patterns between the habitats, the turnover in species (i.e., beta diversity) was insignificant. Species accumulation curves (SAC) constructed using both parametric and non-parametric species richness estimators revealed that the asymptote of species richness was achieved by a low number of sample replicates in both habitats. The temperature and pH of the substratum on testate amoebae distribution patterns suggest the importance of additional background factors on testate amoebae community structure. Further studies involving more biotopes, seasons, and trophic interactions are recommended to document a complete record of testate amoebae diversity and their interactions with environmental gradients in the tropical forest biomes of northeastern India.     

Consequences of Fragmentation of Tropical Moist Forest for Birds and Their Role in Predation of Herbivorous Insects

The consequences of habitat alteration on the role of understory insectivorous birds as predators of herbivorous insects in tropical forests are poorly understood. To examine whether fragmentation may affect the top–down controls of herbivory, we compared the number of species, individuals, and the community structure of insectivorous birds between fragments and continuous tropical moist forest in Mexico. We also registered insect herbivore abundances and conducted a larvae predation experiment to evaluate the potential role of insectivorous birds as predators of herbivorous insects. We recorded 63 bird species from 22 families, 43 percent of which were insectivorous birds. Species richness, abundance, and diversity of the avian community were higher in continuous forest compared with forest fragments. For insectivorous birds in particular, there was low similarity in avian insectivore communities between forest types, and forest fragments had more heavily dominated communities of avian insectivores. During the dry season, forest fragments presented significantly higher predation rates on artificial caterpillars, and lower abundance of herbivorous Lepidoptera larvae, compared with continuous forest. Furthermore, there was a significant negative correlation between artificial caterpillar predation rate and larval Lepidoptera abundance, with higher rates of predation in sample sites of low Lepidoptera abundance. Hence, the potentially greater light in the dry season combined with a more dominated avian insectivore community in forest fragments may facilitate increased predation by avian insectivores, resulting in a decline in abundance of larval Lepidoptera, with implications for the process of insect‐driven herbivory in forest fragments.     

Biodiversity inventory of trees in a large-scale permanent plot of tropical evergreen forest at Varagalaiar, Anamalais, Western Ghats, India

A permanent plot of 30 ha (600 × 500 m²) was established for long-term ecological research on biodiversity and forest functioning in a tropical evergreen forest at Varagalaiar, Anamalais, Western Ghats. This paper gives the results of the first census of trees in the 30 ha plot. All trees 30 cm gbh were permanently tagged with sequentially numbered aluminium tags and their girth measured. 148 tree species (in 120 genera and 49 families) were enumerated in a total sample of 13,393 individuals. Species diversity, density and dispersion patterns were determined. The mean species richness, density and basal area per hectare were 65 species, 446 stems and 36.26 m² respectively. The Sorensen similarity index for thirty 1-ha subplots varied from 0.7 to 0.9, indicating the homogeneity in species composition of the stand. The pronounced species hierarchy has resulted in the dominance of four species that occupy four different forest storeys: Drypetes longifolia (lower storey) Reinwardtiodendron anamallayanum (middle storey), Poeciloneuron indicum (upper storey) and Dipterocarpus indicus (emergent). The forest was dominated by Euphorbiaceae in terms of richness (18 species) and abundance of species (3788 stems), and Dipterocarpaceae based on the contribution to basal area (18.4%). Species richness and density decreased with increasing girth-class. Girth class frequency of the stand exhibited an expanding population of trees. Twenty-nine tree species, analysed for spatial dispersion at 1-ha scale, exhibited both clumped and uniform patterns, except Vateria indica which was randomly distributed in one hectare. Repeat census scheduled for subsequent years, will elucidate the behaviour of the individual species and the population dynamics of the tree flora and will be useful for forest conservation and management. It will also help to monitor human activity within this forest.     

The Importance of Tropical Rain Forest Fragments to the Conservation of Plant Species Diversity in Los Tuxtlas, Mexico

Of what value are forest fragments to the conservation of the tropical rain forest diversity for a landscape? We compared the changes in composition, diversity, and plant structure of 15 small (1–76 ha) relatively unprotected forest fragments with those of a large (700 ha) well protected fragment (LWPF) in Los Tuxtlas, Mexico. The trees, shrubs, lianas, palms, and herbs with dbh?≥?2.5 cm were sampled in 1000 m² at each site. For each ecological group (based on light requirements for germination: primary, secondary, and non-secondary light demanding, NSLD, species) and life form, estimates of species diversity, density, and basal area were analyzed using a stepwise multiple regression to determine whether there were any relationships between these variables and fragment characteristics (size, shape index, and isolation). The composition and plant structure of LWPF were different from those of the small fragments and large trees are absent from the canopy of the latter. Fragment size best explained the differences in composition and plant structure. Species composition in the largest fragments was similar to that of LWPF, but there was no significant difference in total richness between LWPF and the fragments, even though both the richness and abundance of secondary and NSLD species did differ. LWPF had more large primary trees in the canopy, and a greater abundance and basal area of palms and herbs. For tropical rain forest conservation, it is important to maintain the greatest possible number of large fragments and establish policies that prevent forest remnants from being further reduced in size and increasingly isolated from each other.     

Species richness,abundance and diversity of ichneumonid wasps in Japanese beech forests impacted by sika deer and sawfly herbivory

We investigated the community structure of ichneumonid wasps inhabiting beech forests at six sites in the Tanzawa Mountains of Japan under different magnitudes of impact by sika deer Cervus nippon and beech sawfly Fagineura crenativora on vegetation. Using yellow flight-interception traps, we captured 2,528 ichneumonid wasps representing 367 species in 23 subfamilies. The number of species at each site ranged from 77 to 136 and approximately 80% of these were low-density species (i.e. only one to two individuals captured per site). The number of individuals at each site ranged from 248 to 897, and the percentage of the beech sawfly parasitoids varied widely from 1% to 57%. The numbers of species in parasitoid groups categorized according to their hosts, that is, sawfly (not including the beech sawfly), Lepidoptera, woodborer, fungivore or the others, did not greatly differ among the study sites. Parasitoids attacking herbivorous insects exceeded others in species richness and abundance at all sites. Six sites were classified into four groups in terms of abundance of the host groups when excluding the parasitoids of the beech sawfly, but into only two groups when including these parasitoids. Species diversity and evenness were the highest at the least impacted site even if the beech sawfly parasitoids were excluded from calculation. We suggested some environmental factors, such as groundcover vegetation, abundance of the beech sawfly and structure and age of forest stands, that could have affected the community structure of ichneumonid wasps in the beech forests.     

浙江西天目山主要森林类型的苔藓多样性比较

苔藓是森林的重要组分, 是森林保护区的重要保护对象, 在物种资源和生态系统功能维护中有重要作用。该研究以浙江西天目山国家自然保护区内7种主要森林类型(落叶矮林、落叶阔叶林、常绿-落叶阔叶混交林、常绿阔叶林、针阔混交林、针叶林和竹林)内的苔藓植物为对象, 调查了32个10 m × 10 m的样地, 记录地面生苔藓植物盖度和树附生苔藓植物多度, 采用重要值、相似性系数、多样性指数分析了森林类型间的苔藓植物多样性差异。共采集969份标本, 隶属41科84属142种, 其中苔类植物13科18属33种, 藓类植物28科66属109种, 优势科为灰藓科、青藓科和羽藓科。2种混交林(常绿-落叶阔叶混交林和针阔混交林)的物种丰富度和多样性指数均高于其余5种森林, 其中物种丰富度以针阔混交林最高, 苔藓植物多样性则以常绿-落叶阔叶混交林最高, 竹林两者均为最低。海拔等环境因子较为接近的植被类型的苔藓植物多样性相似性较高, 常绿阔叶林与针叶林相似性最高, 而落叶矮林和竹林相似性最小。     

海南岛尖峰岭的植被垂直带及林型

本文研究了海南岛尖峰岭的植被垂直带和植被类型的分布与特点,探索热带林林型分类的方法和依据,对尖峰岭划分了四个植被垂直带,六个植被类型,十五个林型组和二十五个林型,为合理经营及开发利用尖峰岭的森林提供科学依据。     

Diversity of the order Lepidoptera (Hesperioidea and Papilionoidea) from Corrientes city, Argentina

Urbanization is one of the most important threats for biodiversity. Among many different organisms, butterflies are useful indicators of environment diversity and quality. The aim of this study was to investigate the Lepidoptera from Corrientes city. Random samplings were performed at two sites: a native forest situated in Santa Catalina district and an urban area, Parque Mitre. The captures were carried out using entomological nets, at four seasons between January to October 2007. A total of 1 114 butterflies, represented by six families: Hesperiidae, Lycaenidae, Nymphalidae, Papilionidae, Pieridae and Riodinidae and 18 subfamilies were recorded. Fifty-nine genera and 75 species were identified; Anartia jatrophae jatrophae was the most abundant species at both localities. This species and Urbanus procne, Phoebis sennae marcellina, Pyrgus orcus and Dryas iulia alcionea were, among other seven, captured at all months. Highest values of abundance were registered during the warmest seasons. Santa Catalina presented the largest abundance (n = 701), richness (S = 74) and diversity (H' = 3.87). A total of 413 individuals and 52 species were identified at Parque Mitre, and Shannon diversity index was 3.58. The obtained data reveals a high species richness and similarity at both sites.     

Woody Species Alpha‐diversity and Species Abundance Distributions in an African Semi‐deciduous Tropical Rain Forest

Understanding plant species diversity patterns and distributions is critical for conserving and sustainably managing tropical rain forests of high conservation value. We analyzed the alpha‐diversity, species abundance distributions, and relative ecological importance of woody species in the Budongo Forest, a remnant forest of the Albertine Rift in Uganda. In 32 0.5‐ha plots, we recorded 269 species in 171 genera and 51 families with stems of ≥2.0 cm in diameter at breast height (dbh). There were 53 more species with stems of ≥2.0 cm dbh than with stems of ≥10 cm dbh, of which 33 were treelets and 20 were multi‐stemmed shrubs. For both minimum stem diameter cut‐offs (i.e., ≥2 cm dbh vs. ≥10 cm dbh), the Fabaceae, Euphorbiaceae, Ulmaceae, and Meliaceae families and the species Cynometra alexandri, Lasiodiscus mildbraedii, and Celtis mildbraedii had the highest relative ecological importance. The relative ecological importance of some species and families changed greatly with the minimum stem diameter measured. Alpha‐diversity, species richness, and species abundance distributions varied across historical management practice types, forest community types, and as a function of minimum stem diameter. Species richness and Shannon–Weiner diversity index were greater for species with stems of ≥2.0 cm dbh than of ≥10 cm dbh. The decrease in species evenness with an increasing number of plots was accompanied by an increase in species richness for trees of both minimum diameters. This forest is characterized by a small number of abundant species and a relatively large proportion of infrequent species, many of which are sparsely distributed and with restricted habitats. We recommend lowering the minimum stem diameter measured for woody species diversity studies in tropical forests from 10 cm dbh to 2 cm dbh to include a larger proportion of the species pool.     

Seed dispersal modes of tree species and their relation with altitudinal gradient from tropical forests of Eastern Ghats,India

The present study reports the seed dispersal modes of tree species and their relationship with altitudinal gradient from six tropical forests of Eastern Ghats located in India. Anemochory, autochory and zoochory are the three major types of seed dispersal modes recognized for the 272 tree species recorded from a total of 120 0.5 ha area. The predominant dispersal mode is zoochory with 58% of the total tree abundance and 69% of total species richness, followed by autochory with 30% and 19%, and anemochory 12% and 12%, respectively. One way ANOVA revealed that the species richness as well as tree abundance of the three dispersal modes varied significantly across the six tropical forest sites. Regression analysis revealed that both the tree species richness and abundance of zoochory dispersal mode had positive relation with altitude of forest location, while, no such relation was observed for the other two dispersal modes. This study shows that the zoochory increases in species richness and tree abundance with increasing altitude. This may be attributed to high rainfall supporting evergreen forest types with high ratio of animal dispersed tree species in forests at high altitude. However, further studies on these aspects are warranted to draw a significant statement. The predomination of zoochory dispersal mode in this study is comparable with earlier studies in tropical forests elsewhere.