Tropical Forests Of India Research Articles

Effect of anthropogenic disturbance on biomass allocation to different above- and below-ground vegetation components of a dry tropical forest in India

Effect of anthropogenic disturbance on biomass allocation to different above- and below-ground vegetation components of a dry tropical forest in India

Camera trap surveys reveal a wildlife haven: mammal communities in a tropical forest adjacent to a coal mining landscape in India

Having knowledge of the status and distribution of species in a specific geographic area is crucial for creating efficient conservation strategies. In this study, we evaluated the abundance and diversity of medium to large sized mammals in a tropical forest in India that has been greatly impacted by coal mining. Using camera traps between June 2018 and December 2018, we recorded 27 mammal species over 3432 trap-nights in 81 camera trap stations within the study area. The photo-captured species included both common and high conservation value threatened species, such as tiger Panthera tigris, leopard P. pardus, sloth bear Melursus ursinus, Asian elephant Elephas maximus, Gaur Bos gaurus, Indian pangolin Manis crassicaudata, and four-horned antelope Tetracerus quadricornis. Wild boar Sus scrofa was found to be the most frequently photo-captured and widespread species. Our study provides valuable data on the species inventory and the relative abundance of species in the area, highlighting its significance for mammal conservation. It also emphasizes the need for effective conservation management strategies to protect the remaining forest fragments containing high diversity of mammals, including several threatened species in India.

Insights into human‐wildlife coexistence through temporal activity pattern overlaps in a neglected tropical forest in India

AbstractTropical forests experience high levels of anthropogenic pressure from human activities for the collection of forest products, hunting, and movement of domestic animals that affect circadian temporal activity patterns of mammals. Areas with different protection statuses might show differences in mammal circadian activity because of variation in human use intensity. In this study, we assess if human activity could be a predictor shaping the mammal circadian activity patterns in the Eastern Ghats, a neglected tropical forest landscape in India that experiences high human activity. We present results from camera trap surveys of mammal circadian temporal activity patterns in Papikonda National Park (PNP) and its buffer in the Northern Eastern Ghats hill region. We observed a high overlap between human and mammal activity patterns, particularly with herbivorous species. Mammals displayed high crepuscular activity, particularly herbivores; carnivores, however, were also active during the day. This study provides the first insights on circadian temporal activity patterns of mammals in a protected area and its buffer in India's poorly known Eastern Ghats. We discuss these findings in the context of hunting pressure by humans, protection status, and its implications for mammal behavior in the Eastern Ghats and tropical forests across India.Abstract in Telugu is available with online material.

Description of five new eulophid species (Hymenoptera: Eulophidae) associated with leaf vein galls of Madhuca longifolia (J. Koenig) (Sapotaceae) in India.

Five species of eulophids were reared from the leaf vein galls of Madhuca longifolia (Koenig) (Sapotaceae), which is a multipurpose tree in the tropical forests of India. Surveys from 2015 to 2018 in the states of Jharkhand, Chhattisgarh and Uttarakhand revealed that M. longifolia were heavily galled. Rearing of galls during 201516 resulted in emergence of only one species of Selitrichodes (Hymenoptera: Eulophidae), but in subsequent rearings during 2017 to 2018 an additional 4 eulophid species were found to be associated with these galls. Two species belonged to genus Aprostocetus Westwood, one to genus Quadrastichus Girault and one to Chrysonotomyia Ashmead. All five speciesSelitrichodes madhucae Singh Kaneria sp. nov., Aprostocetus madhucae Singh sp. nov., A. dehradunensis Singh sp. nov., Quadrastichus manmohani Singh sp. nov. and Chrysonotomyia madhucae Singh sp. nov. are new to science and described from both female and male specimens. Some observations on their biology are also given.

Remote sensing-based biomass estimation of dry deciduous tropical forest using machine learning and ensemble analysis

Forests play a vital role in maintaining the global carbon balance. However, globally, forest ecosystems are increasingly threatened by climate change and deforestation in recent years. Monitoring forests, specifically forest biomass is essential for tracking changes in carbon stocks and the global carbon cycle. However, developing countries lack the capacity to actively monitor forest carbon stocks, which ultimately adds uncertainties in estimating country specific contribution to the global carbon emissions. In India, authorities use field-based measurements to estimate biomass, which becomes unfeasible to implement at finer scales due to higher costs. To address this, the present study proposed a framework to monitor above-ground biomass (AGB) at finer scales using open-source satellite data. The framework integrated four machine learning (ML) techniques with field surveys and satellite data to provide continuous spatial estimates of AGB at finer resolution. The application of this framework is exemplified as a case study for a dry deciduous tropical forest in India. The results revealed that for wet season Sentinel-2 satellite data, the Random Forest (adjusted R2 = 0.91) and Artificial Neural Network (adjusted R2 = 0.77) ML models were better-suited for estimating AGB in the study area. For dry season satellite data, all the ML models failed to estimate AGB adequately (adjusted R2 between −0.05 – 0.43). Ensemble analysis of ML predictions not only made the results more reliable, but also quantified spatial uncertainty in the predictions as a metric to identify its robustness.

First fossil evidence of Indian tulip tree

ABSTRACT Thespesia populnea (L) Sol. ex Corrêa (Malvaceae), known as the Indian tulip tree, is a well-known fast-growing, economically and ecologically important evergreen species in the tropical forests of India. However, no reliable fossil evidence of Thespesia has been reported from the Cenozoic sediments of India so far. Here, we document for the first time a well-preserved leaf impression similar to extant leaves of Indian tulip tree from the latest Neogene (Pliocene: Rajdanda Formation) sediments of Chotanagpur Plateau, eastern India. The leaf specimen has a broadly ovate mesophyllous blade, with a conspicuous acuminate apex (drip-tip), a cordate base, a stout petiole, actinodromous primary veins and brochiododromous secondary veins. We recognise the new fossil species Thespesia neopopulnea Hazra, Mahato and Khan sp. nov. The recovery of this species and other earlier-described evergreen taxa from the same formation, suggests the existence of tropical, warm and humid climatic conditions during the depositional period.

Phenology and regeneration status of Terminalia tomentosa (Roxb.) Wight & Arn.: a tropical tree species of Indian forests

ABSTRACT Terminalia tomentosa (Roxb.) Wight & Arn., an important tree species in the tropical forests of India, is often reported to have poor or no regeneration in many parts of the country. The present study was conducted to evaluate the population structure and regeneration status of the species in three different forest types of the Similipal Biosphere Reserve, along with phenological behaviours for two consecutive years. Leaf initiation was positively correlated with fruit senescence (r = 0.76, p < 0.01) and flower initiation (r = 0.63, p < 0.01). However, a negative correlation was found between leaf initiation (LF2) and leaf senescence (LF5) (r = −0.42, p < 0.05). Principal Component Analysis showed that maximum temperature and rainfall in a given month are the main factors for pre-monsoon events (leaf senescence and fruit senescence) and post-monsoon events (growth and maturation of leaves and fruits). The results also revealed that regeneration failure of T. tomentosa was not due to phenological intensity but possibly to wrong phenological timing of fruit maturation. This study on regeneration status and phenological information of T. tomentosa could help develop strategies for conservation and management of this tropical tree species in its natural ecosystem.

Edge effects alter the role of fungi and insects in mediating functional composition and diversity of seedling recruits in a fragmented tropical forest.

In fragmented forests, proximity to forest edges can favour the establishment of resource-acquisitive species over more resource-conservative species. During seedling recruitment, resource-acquisitive species may benefit from either higher light availability or weaker top-down effects of natural enemies. The relative importance of light and enemies for recruitment has seldom been examined with respect to edge effects. In a human-modified wet tropical forest in India, we first examined how functional traits indicative of resource-acquisitive vs. resource-conservative strategies, i.e. specific leaf area (SLA), leaf dry matter content, wood density and seed size, explained interspecific differences in densities of seedling recruits with distance to the forest edge. Then, we checked whether fungicide and insecticide treatments and canopy openness (proxy for light availability) explained edge effects on trait-mediated changes in seedling density. Finally, we examined whether light availability and natural enemy activity explained edge effects on functional diversity of seedling recruits. Up to 60 m from edges, recruit densities increased with decreasing seed size, but not at 90-100 m, where recruit densities increased with higher SLA. Trait-mediated variation in recruit densities changed with pesticides only at 90-100 m: compared with control plots, fungicide increased recruit densities for low SLA species and insecticide increased smaller seeded species. For SLA, wood density and seed size, functional diversity of recruits was higher at 90-100 m than at 0-5 m. At 90-100 m, fungicide decreased functional diversity for SLA and insecticide reduced seed size diversity compared with control plots. Canopy openness explained neither variation in recruit density in relation to traits nor functional diversity. Altered biotic interactions can mediate local changes to trait composition and functional diversity during seedling recruitment in forest fragments, hinting at downstream effects on the structure and function of human-modified forests.

Bits and pieces: Forest fragmentation by linear intrusions in India

Linear infrastructure development is an important driver of forest fragmentation leading to habitat and biodiversity loss as well as disruption of critical ecosystem processes. The tropical forests of India are increasingly impacted by infrastructure development. Little quantitative information is available on the extent of fragmentation due to linear infrastructure on these habitats. Here, we quantified fragmentation due to linear infrastructure by studying forest structural connectivity. We compared the existing forest patch characteristics with a scenario that excluded all linear infrastructure. We classified forest patches into three different fragmentation categories that combined information on patch size, inter patch distance and percentage perforations. Results show that power-transmission lines and roads were the most common infrastructure features within forests. We found a 6% increase in the number of forest patches due to the construction of linear infrastructure. Forest patches >10,000 km2 in size were severely affected and there was a 71.5 % reduction in the number of such patches. We found that 86 % of the existing forest patches are in the small (median patch size <1 km2) and isolated (a median distance of 155 m) category. The density of linear infrastructure inside protected areas was similar to density in non-protected forested areas. Our results highlight the need to minimize the effects of fragmentation in the future by considering re-routing or bundling of infrastructure. When infrastructure is unavoidable, there is a need to mitigate their potential impacts. The results of this study have been made publicly accessible (https://indiaunderconstruction.com) to provide information on 'where' to avoid future linear infrastructure development and to make informed decisions which can lead to optimally designed local management plans.

Age constraints on a Neogene tropical rainforest in China and its relation to the Middle Miocene Climatic Optimum

Tropical rainforests have strongly influenced Earth systems throughout their evolutionary history. Plant taxa found in the Fotan Group of Fujian Province indicate that an Asian tropical rainforest prevailed in southeastern China during the Miocene. Abundant insect-bearing ambers co-occur with diagnostic plant fossils in outcrop. Fotan Group fossils demonstrate that highly diverse tropical ecosystems existed during the early Neogene in southeastern China. This study reports a robust 40Ar/39Ar age of 14.7 ± 0.4 Ma for the Fotan fossils. This age constrains interpretations of 1) when tropical rainforest ecosystems developed in China, 2) whether the Fotan flora temporally overlapped with the Asian tropical forest in India, and 3) whether the Middle Miocene Climatic Optimum triggered expansion of tropical rainforests in Asia. A precise age for Fotan units provides important constraints on the biogeographic history of the field area and paleographic models linking Asian and Indian biota.

Algal flora of barks of tropical forests of Western Ghats-Perspectives of research

The bark algae constitutes epiphloeic algae which occur on the tree barks. Along with epiphyllic algae which occur on leaves together called epiphytic algae (Haffmann 1989). The epiphytic algae are terrestrial algae found in extreme environments characterized by humidity or by low/high temperature or light intensity. Being in habitats frequently fluctuations of environmental conditions, occur in contrast with the mostly stable aquatic environments. Having exposed to stress situations terrestrial algae develop morphological and physiological adaptations. The prokaryotic blue green algae along with eukaryotic green algae shared major constituents of terrestrial algal populations and the group exists diversity. However the terrestrial algal diversities poorly understood, though they play important role in biodiversity, ecological and economic values. Among the terrestrial algal flora, the algal flora of barks are one of the important components of terrestrial subaerial habitat of tropical region in general and tropical rain forests in particular. The details of investigation on bark algae of tropical forests of India are not available till date except a few scattered reports which deal with occurrence and systematics (Fristch 1907, Haffmann 1989, Fremy 1930). Though the research on bark algae of tropical ecosystem were initiated during the latter part of the 19th century, till date no comprehensive research papers on bark algae of the tropical rain forests are available. An attempt is made to review the potential prospective of investigations on bark algae of tropical ecosystems, based on the earlier literatures with reference to India and neibouring countries. The research paper is also discussed in relation to contemporary research which has carried out in the South Western regions of the India, where lies Western Ghats, which is one of the hot spots of biodiversity.

Spatio-temporal interactions facilitate large carnivore sympatry across a resource gradient.

Species within a guild vary their use of time, space and resources, thereby enabling sympatry. As intra-guild competition intensifies, such behavioural adaptations may become prominent. We assessed mechanisms of facilitating sympatry among dhole (Cuon alpinus), leopard (Panthera pardus) and tiger (Panthera tigris) in tropical forests of India using camera-trap surveys. We examined population-level temporal, spatial and spatio-temporal segregation among them across four reserves representing a gradient of carnivore and prey densities. Temporal and spatial overlaps were higher at lower prey densities. Combined spatio-temporal overlap was minimal, possibly due to chance. We found fine-scale avoidance behaviours at one high-density reserve. Our results suggest that: (i) patterns of spatial, temporal and spatio-temporal segregation in sympatric carnivores do not necessarily mirror each other; (ii) carnivores are likely to adopt temporal, spatial, and spatio-temporal segregation as alternative mechanisms to facilitate sympatry; and (iii) carnivores show adaptability across a gradient of resource availability, a driver of inter-species competition. We discuss behavioural mechanisms that permit carnivores to co-occupy rather than dominate functional niches, and adaptations to varying intensities of competition that are likely to shape structure and dynamics of carnivore guilds.

Impact of the Invasive WeedLantana camara(Verbenaceae) on Butterfly Behaviour and Habitat Use in a Tropical Forest in India.

Invasive species are thought to influence native biodiversity through a wide range of direct and indirect effects. We examined the influence of an invasive plant, Lantana camara, on butterfly assemblages in a tropical forest in India. Lantana camara typically dominates the understorey in. invaded areas and might therefore reduce the availability of resources and microhabitats essential for butterflies. We hypothesized that butterflies would show reduced use of lantana-dominated habitat when compared with native vegetation. We evaluated such reduced habitat use by testing for (1) reduced levels of behaviours other than feeding and (2) fewer butterfly species and individuals in lantana-dominated habitat patches. To test these expectations, three plots of 30 x 30 meters each were laid in lantana-dominated and native-vegetation patches. In total, three plots in native-vegetation and three in lantana-dominated habitat were marked. Butterfly behaviour was measured through focal-animal follows, and abundance and species numbers were investigated using point sampling inside these plots. We found that butterflies showed substantial behavioural differences between lantana-dominated and native-vegetation plots, indicating a possiblity that the invaded patches were relatively less suitable for several butterfly activities. Furthermore, fewer butterfly species and individuals were seen in lantana-dominated compared with native-vegetation habitat, indicating that lantana invasion results in reduced suitability of a habitat. Whether local behavioural effects of invasive plants, such as reduced habitat use, can lead ultimately to reduced population sizes and local extinctions will need to be examined.

Fruit resource tracking by hornbill species at multiple scales in a tropical forest in India

Abstract:The fruit-tracking hypothesis predicts a positive association between frugivores and fruit abundance over space and time. We documented hornbill diets and examined the relationship between fruit abundance and abundance of three hornbill species (Buceros bicornis, Rhyticeros undulatus and Aceros nipalensis) in the Eastern Himalaya from 2009–2012. The study was carried out at three scales: at the largest scale of the study area (15 km2), at the intermediate scale – eight 3-ha patches within the study area and at the smallest scale of individual fruiting trees. Ninety-one per cent of the 64 foraging sightings of the great hornbill were on figs while more than 50% of the foraging sightings of the wreathed (83) and rufous-necked hornbills (87) were on non-fig fruits. At the largest scale, wreathed hornbill abundance and ripe fruit abundance peaked in the non-breeding season. At the intermediate scale, wreathed hornbill abundance was positively associated with non-fig fruit availability while rufous-necked hornbill abundance was negatively associated with non-fig fruit availability. At the smallest scale, great and rufous-necked hornbill abundances were correlated with fig and non-fig fruit crop sizes, respectively. The three hornbill species track fruit availability at different scales based on diet, which has implications for their role in seed dispersal.

Effect of anthropogenic disturbances on biomass and carbon storage potential of a dry tropical forest in India

The forests of Chhattisgarh are very well known for its species richness, diversity, biomass, carbon stock and productivity. The present study was carried out at Katghora forest division under Bilaspur circle of Korba district, Chhattisgarh considering three sites viz., least, moderately and highly disturbed site to estimate biomass and carbon storage in relation to anthropogenic disturbances. For collection of data quadrats were selected under stratified random sampling design. For enumeration of tree and saplings ten quadrats of 10 m × 10 m were laid and each species counted separately. The tree density varies from 100-510 stems ha-1 across study sites. Total biomass in the present study was between 127.69 t ha-1 and 227.71 t ha-1. Total above ground biomass was between 111.20 t ha-1 and 199.42 t ha-1, whereas total below ground biomass varied from 16.49-28.29 t ha-1, respectively. The total carbon storage across the sites were ranged from 55.125 to 98.548 t C ha-1 found higher under least disturbed site and lowest under medium disturbed site. Carbon storage pattern according to girth class followed the similar trend of distribution as was in the case of biomass. It has least proportion in small girth class and maximum storage under the higher girth class. It is evident from the study that disturbances have significant impact on density, vegetation diversity, biomass accumulation and carbon storage pattern. Conservation affords are required to control on disturbances and for the natural recovery of forest ecosystem.

Rodent seed predation: effects on seed survival, recruitment, abundance, and dispersion of bird-dispersed tropical trees

Tropical tree species vary widely in their pattern of spatial dispersion. We focus on how seed predation may modify seed deposition patterns and affect the abundance and dispersion of adult trees in a tropical forest in India. Using plots across a range of seed densities, we examined whether seed predation levels by terrestrial rodents varied across six large-seeded, bird-dispersed tree species. Since inter-specific variation in density-dependent seed mortality may have downstream effects on recruitment and adult tree stages, we determined recruitment patterns close to and away from parent trees, along with adult tree abundance and dispersion patterns. Four species (Canarium resiniferum, Dysoxylum binectariferum, Horsfieldia kingii, and Prunus ceylanica) showed high predation levels (78.5-98.7%) and increased mortality with increasing seed density, while two species, Chisocheton cumingianus and Polyalthia simiarum, showed significantly lower seed predation levels and weak density-dependent mortality. The latter two species also had the highest recruitment near parent trees, with most abundant and aggregated adults. The four species that had high seed mortality had low recruitment under parent trees, were rare, and had more spaced adult tree dispersion. Biotic dispersal may be vital for species that suffer density-dependent mortality factors under parent trees. In tropical forests where large vertebrate seed dispersers but not seed predators are hunted, differences in seed vulnerability to rodent seed predation and density-dependent mortality can affect forest structure and composition.

Diversity of deciduousness and phenological traits of key Indian dry tropical forest trees

• In seasonally dry tropical forests deciduousness (leaflessness) is an important strategy of trees to survive in water stress period during summer. Deciduousness is a reflection of interacted effect of seasonal drought, tree characteristics and soil moisture conditions. • The present study aims to document the diversity in leaf pheno-phases in terms of duration of deciduousness (which is reciprocal to growing season length), wood density, leaf mass per area (LMA) and leaf strategy index in 24 important tree species growing in the Vindhyan dry tropical forest in India. • On the basis of phenological observations, the tree species were categorized into two main groups: leaf exchanging species exhibiting overlapping periods of leaf fall and leaf flush, and deciduous species whose timings of leaf flush and leaf fall differ resulting in a time lag (deciduousness) between the completion of leaf fall and initiation of leaf flush. Presence of wide range of deciduousness duration (from ca. a week to 7 months) among dry tropical trees indicates large variations in their growing season length. In the tree species studied, as the duration of deciduousness increased, leaf flushing period decreased significantly but leaf fall period showed little variation. • Differing deciduousness in tree species exhibited substantial differences in their leafing (vegetative growth) pattern, as reflected by ratio of durations of leaf flush to leaf fall (leaf strategy index). Across different species, duration of deciduousness was significantly positively correlated with leaf strategy index, and significantly negatively correlated with both wood density and LMA. • Wide variations in deciduousness, leaf strategy index, wood density and LMA in the 24 species investigated indicate considerable functional diversity in tree species growing in Vindhyan dry tropical region. Variation in seasonal duration of deciduousness among species is reflections of differences in tree functional traits like stem wood density, leaf strategy index and LMA.

Patterns of seed rain and seedling regeneration in abandoned agricultural clearings in a seasonally dry tropical forest in India

Abstract:Forest recovery in abandoned pastures and agricultural fields is often impeded, therefore it is important to understand the factors limiting regeneration. Patterns of seed arrival and regeneration in five abandoned agricultural clearings nested within a seasonally dry tropical forest in India were examined along five transects radiating from the forest edge into the clearings. Wind-dispersed seeds dominated the seed arrival in clearings compared with vertebrate-dispersed seeds: 5563 wind-dispersed seeds and 1094 vertebrate-dispersed seeds of 14 and 13 tree species, respectively, were recorded. Numbers of the former declined steeply with increasing distance from the forest, whereas the latter showed no evident pattern with distance. Seeds of the invasive herb,Chromolaena odorata, were abundant in clearings. Although wind-dispersed seeds greatly outnumbered vertebrate-dispersed seeds, seedlings and saplings of vertebrate-dispersed species were three times more abundant than those of wind-dispersed species, indicating distinct differences in patterns of actual and effective seed dispersal. This points to recruitment limitation, and suggests that seed arrival may not be the principal barrier to regeneration in these clearings. Nonetheless, the clearings are likely to revert to forest over time.

Storage and Flux of Nutrients in a Dry Tropical Forest in India

Storage and flux of N, P, Ca, K and Na were studied in a dry tropical forest. The nutrient concentrations in different growth forms were in the order: herb > shrub > tree, whereas the standing state of nutrients followed the order: tree > shrub > herb. The total storage (kg ha(-1)) in vegetation amounted to 567 N, 37 P, 278 Ca, 256 K and 46 Na. The share of above-ground parts in vegetation storage was 82% for N, 83% for P, 76% for Ca, 85% for K and 79% for Na. From 56 to 71% of foliar N, P and K was withdrawn during senescence. Nutrient input (kg ha(-1) year(-1)) from the vegetation (above-ground + below-ground) to forest floor amounted to 115 N, 8 P, 62 Ca, 38 K and 10 Na compared to total net annual uptake (kg ha(-1)) of 143 N, 10 P, 78 Ca, 52 K and 12 Na, indicating marginal accumulation in the system. Fine roots were as important a pathway of nutrient return as leaf litter. Turnover rate and turnover time for different nutrients on the forest floor ranged, respectively, between 72 and 83% and 1.2 and 1.39 years.

Species Structure, Dry Matter Dynamics and Carbon Flux of a Dry Tropical Forest in India

Species composition, plant biomass and net primary productivity were studied on three sites of a dry tropical forest The forest was characterized by small structure with 38-10.4 m 2 ha −1 tree and 3 1-7 8 m 2 ha −1 shrub basal cover Species diversity was highest for the mid-slope site while the concentration of dominance was greatest for the hill-top stand The beta diversity was 3 1 Total standing crop of vegetation averaged 66 98 t ha −1 with 46 70 t ha −1 in the tree layer, 13.97 t ha −1 in the shrub layer, 0.35 t ha −1 in the herb layer, 2 83 t ha −1 in the litter layer and 3 13 t ha −1 in fine roots Of the total annual litterfall (4 88-6.71 t ha −1 ), 69% was accounted for by leaves and 31% by non-leaf matter Net primary production (NPP) ranged between 11 3 and 19 2 t ha −1 year −1 , to which the contributions of trees, shrubs and herbs averaged 72, 22 and 6%, respectively Contribution of roots to NPP was substantial and ranged from 2 9 to 5 3 t ha −1 year −1 A total of 83% of vegetation carbon was stored in the above-ground plant parts while the above-ground NPP was responsible for 72% of the total carbon input into the system The contribution of foliage, herbaceous vegetation and fine roots to carbon turnover was disproportionately larger compared to their share in the total standing crop Carbon budgeting indicated that the forest was an accumulating system, over at least the short term.