Forest fragmentation and habitat loss are major disruptors of plant–frugivore interactions, affecting seed dispersal and altering recruitment patterns of the dependent tree species. In a ...heterogeneous production landscape (primarily tea and coffee plantations) in the southern Western Ghats, India, we examined effects of surrounding forest cover and fruit crop size on frugivory of four rainforest bird‐dispersed tree species (N = 131 trees, ≥30 trees per species, observed for 623 hr). Frugivore composition differed among the four tree species with the large‐seeded Canarium strictum and Myristica dactyloides being exclusively dependent on large‐bodied avian frugivores, whereas medium‐seeded Persea macrantha and Heynea trijuga were predominantly visited by small‐bodied and large‐bodied avian frugivores, respectively. Using the seed‐dispersal‐effectiveness framework, we identified effective frugivores and examined their responses to forest cover and fruit crop size. Results were idiosyncratic and were governed by plant and frugivore traits. Visitations to medium‐seeded Persea had a positive relationship with forest cover but the relationship was negative for the large‐seeded Myristica. In addition, two of the three effective frugivores for Persea responded to the interactive effect of forest cover and fruit crop size. Frugivore visitations to Heynea were not related to forest cover or fruit crop, and there were too few visitations to Canarium to discern any trends. These results highlight the context‐specific responses of plant–frugivore interactions to forest cover and fruit crop size influenced by plant and frugivore traits.
The effects of fragmentation and overstorey tree diversity on tree regeneration were assessed in tropical rain forests of the Western Ghats, India. Ninety plots were sampled for saplings (1–5 cm ...diameter at breast height (dbh); 5×5-m plots) and overstorey trees (>9.55 cm dbh; 20×20-m plots) within two fragments (32 ha and 18 ha) and two continuous forests. We tested the hypotheses that fragmentation and expected seed-dispersal declines (1) reduce sapling densities and species richness of all species and old-growth species, and increase recruitment of early-successional species, (2) reduce the prevalence of dispersed recruits and (3) increase influence of local overstorey on sapling densities and richness. Continuous forests and fragments had similar sapling densities and species richness overall, but density and richness of old-growth species declined by 62% and 48%, respectively, in fragments. Fragments had 39% lower densities and 24% lower richness of immigrant saplings (presumed dispersed into sites as conspecific adults were absent nearby), and immigrant densities of old-growth bird-dispersed species declined by 79%. Sapling species richness (overall and old-growth) increased with overstorey species richness in fragments, but was unrelated to overstorey richness in continuous forests. Our results show that while forest fragments retain significant sapling diversity, losses of immigrant recruits and increased overstorey influence strengthen barriers to natural regeneration of old-growth tropical rain forests.
Ecological restoration is a leading strategy for reversing biodiversity losses and enhancing terrestrial carbon sequestration in degraded tropical forests. There have been few comprehensive ...assessments of recovery following restoration in fragmented forest landscapes, and the efficacy of active versus passive (i.e., natural regeneration) restoration remains unclear. We examined 11 indicators of forest structure, tree diversity and composition (adult and sapling), and aboveground carbon storage in 25 pairs of actively restored (AR; 7–15 yr after weed removal and mixed‐native tree species planting) and naturally regenerating (NR) plots within degraded rainforest fragments, and in 17 less‐disturbed benchmark (BM) rainforest plots in the Western Ghats, India. We assessed the effects of active restoration on the 11 indicators and tested the hypothesis that the effects of active restoration increase with isolation from contiguous and relatively intact rainforests. Active restoration significantly increased canopy cover, adult tree and sapling density, adult and sapling species density (overall and late‐successional), compositional similarity to benchmarks, and aboveground carbon storage, which recovered 14–82% toward BM targets relative to NR baselines. By contrast, tree height–diameter ratios and the proportion of native saplings did not recover consistently in actively restored forests. The effects of active restoration on canopy cover, species density (adult), late‐successional species density (adult and sapling), and species composition, but not carbon storage, increased with isolation across the fragmented landscape. Our findings show that active restoration can promote recovery of forest structure, composition, and carbon storage within 7–15 yr of restoration in degraded tropical rainforest fragments, although the benefits of active over passive restoration across fragmented landscapes would depend on indicator type and may increase with site isolation. These findings on early stages of recovery suggest that active restoration in ubiquitous fragmented landscapes of the tropics could complement passive restoration of degraded forests in less fragmented landscapes, and protection of intact forests, as a key strategy for conserving biodiversity and mitigating climate change.
Bats play crucial roles in ecosystems, are increasingly used as bio-indicators and are an important component of tropical diversity. Ecological studies and conservation-oriented monitoring of bats in ...the tropics benefit from published libraries of echolocation calls, which are not readily available for many tropical ecosystems. Here, we present the echolocation calls of 15 species from the Valparai plateau in the Anamalai Hills, southern Western Ghats of India: three rhinolophids (Rhinolophus beddomei, R. rouxii (indorouxii), R. lepidus), one hipposiderid (Hipposideros pomona), nine vespertilionids (Barbastella leucomelas darjelingensis, Hesperoptenus tickelli, Miniopterus fuliginosus, M. pusillus, Myotis horsfieldii, M. montivagus, Pipistrellus ceylonicus, Scotophilus heathii, S. kuhlii), one pteropodid (Rousettus leschenaultii) and one megadermatid (Megaderma spasma). Discriminant function analyses using leave-one-out cross validation classified bats producing calls with a strong constant frequency (CF) component with 100% success and bats producing frequency modulated (FM) calls with 90% success. For five species, we report their echolocation calls for the first time, and we present call frequencies for some species that differ from those published from other parts of the species' ranges. This exemplifies the need for more local call libraries from tropical regions to be collected and published in order to record endemic species and accurately identify species whose calls vary biogeographically.
Conflict to Coexistence Sidhu, Swati; Raghunathan, Ganesh; Mudappa, Divya ...
Conservation and society,
10/2017, Letnik:
15, Številka:
4
Journal Article
Recenzirano
Odprti dostop
When leopards are found in human-dominated landscapes, conflicts may arise due to attacks on people or livestock loss or when people retaliate following real and perceived threats. In the plantation ...landscape of the Valparai plateau, we studied incidents of injury and loss of life of people and livestock over time (15 – 25 y) and carried out questionnaire surveys in 29 plantation colonies and eight tribal villages to study correlates of livestock depredation, people’s perception of leopards, and preferred management options for human – leopard interactions. Leopards were implicated in an average of 1.3 (± 0.4 SE) incidents/year (1990 – 2014) involving humans and 3.6 (± 0.8 SE) incidents/year (1999 – 2014) involving livestock, with no statistically significant increasing trend over time. Most incidents of injury or loss of life involved young children or unattended livestock, and occurred between afternoon and night. At the colony level, livestock depredation was positively related to the number of livestock, but decreased with the distance from protected area and number of residents. Half the respondents reported seeing a leopard in a neutral situation, under conditions that resulted in no harm. All tribal and 52% of estate respondents had neutral perceptions of leopards and most (81.9%, n = 161 respondents) indicated changing their own behaviour as a preferred option to manage negative interactions with leopards, rather than capture or removal of leopards. Perception was unrelated to livestock depredation, but tended to be more negative when human attacks had occurred in a colony. A combination of measures including safety precautions for adults and children at night, better livestock herding and cattle-sheds, and building on people’s neutral perception and tolerance can mitigate negative interactions and support continued human – leopard coexistence.
Brown palm civet diet was assessed by examining 1,013 scats between May 1996 and December 1999 in Kalakad-Mundanthurai Tiger Reserve, Western Ghats, India. The brown palm civet is predominantly ...frugivorous, with fruits of 53 native species and four species of introduced plants comprising 97% of its diet. There was high intra- and inter-annual variation in the diet of brown palm civets. Civets adapted to fluctuations in fruit resources by feeding on a diverse range of species and supplementing their year-round, primarily frugivorous, diet with invertebrates and vertebrates. Civets mainly ate fruits of trees and lianas, rarely those of herbs or shrubs. Fruits eaten by civets were mostly small (<1 cm diameter), multi-seeded, pulpy berries, and drupes with moderate to high water content, along with several large (>2 cm) fruits like Palaquium ellipticum, Elaeocarpus serratus, Holigarna nigra, and Knema attenuata. The brown palm civet is a key mammalian seed disperser in the Western Ghats rainforest by being predominantly frugivorous and dispersing a diverse array of plant species. As brown palm civets can persist in fragmented rainforest, they can play a major role in restoration of degraded fragments in these landscapes. The results emphasize the need to recognize the importance of small carnivores as seed dispersers in tropical forests.
Salim Ali’s Fruit Bat Latidens salimalii is an IUCN Red listed Endangered species known only from a few locations in southern India. Here we report three records of Latidens salimalii from the ...Valparai plateau and Anamalai Tiger Reserve in Tamil Nadu where this species has not been previously recorded. This bat was caught in riparian habitats close to or inside intact tropical wet forest in the Western Ghats.
Conservation in human-modified landscapes is important for riparian animals as their habitats extend linearly beyond adjoining protected areas. We examined occupancy and intensity of habitat use of ...Asian small-clawed otters in coffee and tea plantations and an adjoining protected area in the Western Ghats. We sampled 66 stream segments of 500 m length, using spraints as an indicator of habitat use. Several variables characterising the stream and shoreline were also measured. Occupancy, corrected for detection of spraints, was >0.75 in all three land use types, indicating widespread use of the riparian ecosystem in human-modified landscapes. Intensity of habitat use, however, was much lower in tea (2.08 spraints/500 m) and coffee (2.42) plantations than in the protected area (3.86). Using GLMs we identified the abundance of potential refuges (such as boulders and fallen trees), which was greater in the protected area, as the major factor influencing intensity of habitat use. Shoreline diversity, which was lowest in the tea plantation, might also be another factor. The retention of much of the riparian vegetation and the presence of forest fragments which provide refuges have led to wide occupancy of the tea and coffee plantations although with less intensive use. Sand mining, fishing and infrequent poaching might be other reasons for the relatively low use of human-modified landscape. This study highlights the need to retain remnant forests and riparian vegetation, and to control some human activities for integrated management of species like the small-clawed otter in both protected areas and adjoining human-modified habitats.
The responses of bats to land-use change have been extensively studied in temperate zones and the neotropics, but little is known from the palaeotropics. Effective conservation in heavily-populated ...palaeotropical hotspots requires a better understanding of which bats can and cannot survive in human-modified landscapes. We used catching and acoustic transects to examine bat assemblages in the Western Ghats of India, and identify the species most sensitive to agricultural change. We quantified functional diversity and trait filtering of assemblages in forest fragments, tea and coffee plantations, and along rivers in tea plantations with and without forested corridors, compared to protected forests.
Functional diversity in forest fragments and shade-grown coffee was similar to that in protected forests, but was far lower in tea plantations. Trait filtering was also strongest in tea plantations. Forested river corridors in tea plantations mitigated much of the loss of functional diversity and the trait filtering seen on rivers in tea plantations without forested corridors. The bats most vulnerable to intensive agriculture were frugivorous, large, had short broad wings, or made constant frequency echolocation calls. The last three features are characteristic of forest animal-eating species that typically take large prey, often by gleaning.
Ongoing conservation work to restore forest fragments and retain native trees in coffee plantations should be highly beneficial for bats in this landscape. The maintenance of a mosaic landscape with sufficient patches of forest, shade-grown coffee and riparian corridors will help to maintain landscape wide functional diversity in an area dominated by tea plantations.
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•Bat functional diversity was similar in shade coffee to protected forests.•Bat functional diversity was similar in forest fragments to protected forests.•Tea plantations retain far less bat functional diversity than shade grown coffee.•Large bats and bats with short, broad wings were filtered out in modified habitats.•Riparian corridors help retain bat functional diversity in a modified landscape.
Tropical rainforest remnants in human-modified landscapes exhibit varying levels of degradation, from highly degraded open-canopied and invasive plant-invaded forests to closed-canopy forests that ...appear structurally intact. The former are frequently identified as being in a state of arrested recovery, and targeted for restoration, but restoration needs and opportunities in the latter remain underexplored. Using tree and seedling data from 105 plots spanning a canopy cover gradient in rainforest fragments and 19 plots in relatively-intact “reference” rainforests in India's Western Ghats mountains, we show that the floristic composition, conservation significance, and carbon stocks of closed-canopy fragments (CC) more closely resemble open-canopy fragments (OC) than reference rainforests (RR). For example, densities of old-growth forest species, endemic/threatened species, and carbon stocks, increased from 15 %, 28 %, and 22 % of reference values in OC to 32 %, 46 %, and 35 % in CC, respectively, while tree community similarity to RR showed no increase from OC to CC (15 %). Seedlings mirrored this pattern, offering little indication of natural recovery in closed-canopy fragments. Further, we show using simulations that seedling enrichment in closed-canopy fragments can initiate varying levels of floristic and functional recovery towards reference targets. Our findings illustrate that seemingly structurally-intact tropical rainforest fragments can remain arrested in a floristically degraded condition, and represent worthwhile targets for ecological restoration. Such forests expand opportunities for restoring conservation-priority and high carbon-storing species using relatively low-cost methods (e.g., enrichment planting), which can complement intensive restoration of highly degraded forests and minimally-assisted natural recovery of less-fragmented forests.
•Restoration targets forests that are highly structurally- and floristically-degraded.•Structurally less-degraded forests can remain floristically highly degraded.•Closed-canopy forests in fragmented landscapes warrant greater restoration attention.•Restoring closed-canopy fragments can initiate biodiversity and carbon recovery.
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