Article

Effects of extractive use on forest birds in Western Himalayas: Role of local and landscape factors

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... Moreover, majority of the rural population of the Himalayan region still depends upon primary forest for fodder, timber, fuelwood, etc. Such reliance on forests resulting into constant alteration and degradation of habitats have greatly affected the avian community especially forest specialists, pollinators, and insectivorous species along with other faunal components (Gupta et al., 2019;Menon et al., 2019;Shahabuddin et al., 2021). In order to minimize the human interference and conserve the habitats and associated biodiversity, including birds, several initiatives have been taken at the national and international level. ...
... This chapter has indicated mis-match between distribution of PA network and biodiversity including birds in the Himalaya. It has also been highlighted that significant human Apple Academic Press Author Copy population depends upon forest resources leading to constant alteration and degradation of habitats affecting the avian community especially forest specialists, pollinators, and insectivorous species (Gupta et al., 2019;Menon et al., 2019;Shahabuddin et al., 2021). Several studies have recorded canopy cover, along with the understorey vegetation density, as the two most important factors influencing the bird diversity (Sekercioglu et al., 2002;Martin and McIntyre, 2007;Shahabuddin and Kumar, 2007;Dahal et al., 2015;Menon et al., 2019). ...
... It has also been highlighted that significant human Apple Academic Press Author Copy population depends upon forest resources leading to constant alteration and degradation of habitats affecting the avian community especially forest specialists, pollinators, and insectivorous species (Gupta et al., 2019;Menon et al., 2019;Shahabuddin et al., 2021). Several studies have recorded canopy cover, along with the understorey vegetation density, as the two most important factors influencing the bird diversity (Sekercioglu et al., 2002;Martin and McIntyre, 2007;Shahabuddin and Kumar, 2007;Dahal et al., 2015;Menon et al., 2019). The extraction of timbers and vegetation in the Himalaya have had negative effects on avifaunal communities, especially the understorey species and forest specialists (Chettri et al., 2005). ...
... Moreover, majority of the rural population of the Himalayan region still depends upon primary forest for fodder, timber, fuelwood, etc. Such reliance on forests resulting into constant alteration and degradation of habitats have greatly affected the avian community especially forest specialists, pollinators, and insectivorous species along with other faunal components (Gupta et al., 2019;Menon et al., 2019;Shahabuddin et al., 2021). In order to minimize the human interference and conserve the habitats and associated biodiversity, including birds, several initiatives have been taken at the national and international level. ...
... This chapter has indicated mis-match between distribution of PA network and biodiversity including birds in the Himalaya. It has also been highlighted that significant human population depends upon forest resources leading to constant alteration and degradation of habitats affecting the avian community especially forest specialists, pollinators, and insectivorous species (Gupta et al., 2019;Menon et al., 2019;Shahabuddin et al., 2021). Several studies have recorded canopy cover, along with the understorey vegetation density, as the two most important factors influencing the bird diversity (Sekercioglu et al., 2002;Martin and McIntyre, 2007;Shahabuddin and Kumar, 2007;Dahal et al., 2015;Menon et al., 2019). ...
... It has also been highlighted that significant human population depends upon forest resources leading to constant alteration and degradation of habitats affecting the avian community especially forest specialists, pollinators, and insectivorous species (Gupta et al., 2019;Menon et al., 2019;Shahabuddin et al., 2021). Several studies have recorded canopy cover, along with the understorey vegetation density, as the two most important factors influencing the bird diversity (Sekercioglu et al., 2002;Martin and McIntyre, 2007;Shahabuddin and Kumar, 2007;Dahal et al., 2015;Menon et al., 2019). The extraction of timbers and vegetation in the Himalaya have had negative effects on avifaunal communities, especially the understorey species and forest specialists (Chettri et al., 2005). ...
Chapter
Himalaya represents a unique landscape displaying varied eco-zones, climatic conditions, large elevation gradient, and enormous natural resources. Among the range of biodiversity, birds are well studied in the Himalaya but findings of research and exploration in the region has not been systematically compiled till date. In this chapter, we provide a detailed account of avifaunal wealth of the Himalaya covering species occurrence, elevation distribution range of each species (wherever available), IUCN threat category, range restricted status, migratory status, population trend, and habitat utilization of Himalayan birds. Based on the review of existing research articles, reference books, and authentic web sources supplemented by our own observations, we have developed a comprehensive database of birds covering all Himalayan states (erstwhile undivided Jammu & Kashmir, Himachal Pradesh, Uttarakhand, Sikkim, Darjeeling, and Kalimpong districts of West Bengal and Arunachal Pradesh) along with neighboring countries Nepal and Bhutan. We also assessed whether the existing protected areas in the region are in congruence with the diversity of birds. We reviewed 1901 literatures and observed that ornithological exploration was initiated in the region in 17th century with rapid pace of research since 1990 reflecting the maximum number of publications (344) in the last decade (2011–2020). The database of birds with reported and potential distribution in the Himalaya comprises 987 species and 385 genera representing 99 avian families. Similarly, out of the total bird species, 180 (18.2%) are water birds and 807 (81.8%) terrestrial species representing ~39% forest specialist, ~30% forest generalist, ~8.2% high altitude birds, and 3.5% open land species. Based on migratory status, 428 species are full migrants followed by 416 resident and 140 altitudinal migrant species. Among the total, IUCN has enlisted 881 species as Least Concerned, whereas 56 species are listed as threatened with extinction (vulnerable 33, endangered 12 and critically endangered 11) along with 49 near-threatened species. We observed a clear mis-match between the elevational distribution of protected areas (along with area coverage) and avian diversity showing maximum area coverage by PAs between 4000 and 5000 m elevation but maximum bird diversity at middle elevation gradient (~2000 m). We also noted the existence of 122 PAs in the region along with 165 notified Important Bird Areas and 19 designated Ramsar sites. We conclude that along with these legally protected conservation sites, human-modified areas (including agricultural lands) outside PAs are important for avian conservation and requires policy intervention.
... Banj oak (Quercus leucotrichophora) occurs in the Western Himalayan Broadleaf Forest biome, a Global 200 Ecoregion and Endemic Bird Area prioritized for conservation attention, due to its high biodiversity and increasing threat levels (Malcolm et al. 2002;Olson and Dinerstein 2002;Birdlife International 2016). Occurring in the mid-altitudes, banj oak-dominated forests are considered to be Pleistocene relicts resembling cloud forests in structural and functional attributes and harbouring high floral diversity (Singh and Singh 1987;Shahabuddin et al. 2017;Menon et al. 2019). Banj oak forests provide critical ecosystem services including support for agrarian livelihoods (Singh 1997;Thadani 1999;Naudiyal and Schmerbeck 2017), as well as hydrological modulation (Pathak et al. 1985, Qazi et al. 2017, nutrient cycling and soil conservation Singh 1986, Singh 1997). ...
... These forests occur within a mosaic of villages, towns, mixed agriculture and chir pine stands. The study area was chosen for its representative mix of land use types, within which forest ecology, avifauna and forest institutions are well-studied (Thadani and Ashton 1995;Thadani 1999;Shahabuddin et al. 2017;Shahabuddin and Thadani 2018;Menon et al. 2019). ...
... However, at the larger scale of this study, we find a more complex combination of bioclimatic, habitat, topographic and anthropogenic factors driving oak forest degradation and change in Western Himalaya. The decline of an oak forest stand is initiated by extractive activities that open up the canopy, reduce understorey density and alter nutrient cycling, converting it to a degraded state Singh 1997;Menon et al. 2019). Our results demonstrate the greater vulnerability of degraded oak stands to pine invasion and growth, supporting earlier observations (Saxena et al. 1984;Singh 1997;Pandey et al. 2020). ...
Article
Oak species worldwide are experiencing declines, with negative consequences for hardwood forests and their associated biodiversity, but the causes of these declines vary across species and habitats. We examine changes in extent of banj oak-dominated (Quercus leucotrichophora) moist temperate hardwood forests in a Western Himalayan landscape between 1991 and 2017. Using classified satellite imagery from 1991, 2001 and 2017, we found that dense banj oak forests have undergone substantial degradation and loss of area, while chir pine (Pinus roxburghii) forests have expanded, largely by replacing degraded banj oak stands. This transition was most likely to occur at sites that had lower levels of winter precipitation and Topographic Wetness Index (TWI) values and more pine forest in the surrounding landscape. Our findings are consistent with known requirements of shade and moisture for the recruitment of banj oak. Loss of banj oak forests is likely to reduce biodiversity and a number of ecosystem services linked to the well-being of local communities.
... Dead, decaying wood tends to be easier to excavate and is a preferred nesting substrate (Kumar et al. 2014). This makes woodpeckers vulnerable to both forestry operations as well as subsistence extraction (Mitra and Sheldon 1993;Styring and Hussin 2004;Menon et al. 2019). Several woodpecker species thus respond negatively to selective logging, lopping of trees and removal of dead wood from the tree and shrub layers (Menon et al. 2019;Du Plessis 1995). ...
... This makes woodpeckers vulnerable to both forestry operations as well as subsistence extraction (Mitra and Sheldon 1993;Styring and Hussin 2004;Menon et al. 2019). Several woodpecker species thus respond negatively to selective logging, lopping of trees and removal of dead wood from the tree and shrub layers (Menon et al. 2019;Du Plessis 1995). ...
... (Pinus roxburghii) which is considered to be an early successional species. According to a previous study, oak-dominated (Quercus spp.) forests found in this biome sustain high bird diversity, with 136 species reported of which 45% are forest specialists (Menon et al. 2019;Shahabuddin et al. 2017). In recent times an increasing human population (both local and tourist) has put heavy pressure on these forest resources, which have also been affected by expanding urbanization and development (Makino 2011;Singh et al. 2014). ...
Article
Full-text available
Woodpeckers (family Picidae) are a specialised group of insectivores that are sensitive to forest degradation and fragmentation. We evaluated the woodpecker taxa as potential indicators of habitat quality and forest bird diversity in temperate moist hardwood forests (1500–2400 m asl), a threatened biome in the Western Himalaya. 74 forest sites, selected to represent a gradient of anthropogenic use, were surveyed for birds, vegetation structure and proportion of land under dense forest in the surrounding landscape. Individual woodpecker species were observed to quantify their foraging niche preferences. We found that forest sites with higher woodpecker richness were also rich in all other bird species. Further, the richness and abundance of woodpeckers and all other birds were affected by similar habitat variables. Four out of the eight woodpecker species occurring in the study area were found to fit our habitat models suitably, with canopy cover, tree density, and forest proportion proving to be important variables. Behavioural observations showed that the same four woodpecker species significantly preferred larger and taller trees for foraging. Given the difficulty of directly monitoring forest characteristics and total bird diversity over large landscapes, consistent monitoring of sensitive woodpecker species can provide answers to both. Further, as woodpeckers are moderately common and conspicuous birds, areas with high woodpecker diversity can be easily identified and prioritised for conservation.
... For instance, the impacts of land use change on bird diversity have been studied in various geographic contexts such as Amazon basin (Barlow et al., 2007;Srinivas and Koh, 2016), Eastern Himalaya (Mandal and Shankar Raman, 2016), Western Ghats in India and Sri Lanka (Sreekar et al., 2015) and Mexican highlands Carillo-Rubio et al., 2014). Declines in species abundance can be related largely to reduction in structural complexity and resources of forest habitats as well as alterations in predator-prey and competitive relations (Sol et al., 2020;Menon et al., 2019;Shochat et al., 2006). ...
... Land use change additionally leads to divergence in species composition caused by selective loss and decline in species and functional guilds that are more vulnerable than others (Menon et al., 2019;Sreekar et al., 2015;Srinivas and Koh, 2016). Recent global scale meta-analysis (Newbold et al., 2015;Sol et al., 2020) and predictive modelling exercises (Hinz et al., 2020;Seto et al., 2012) have revealed the patterns of avian loss in terms of vulnerable species and guilds. ...
... Recent global scale meta-analysis (Newbold et al., 2015;Sol et al., 2020) and predictive modelling exercises (Hinz et al., 2020;Seto et al., 2012) have revealed the patterns of avian loss in terms of vulnerable species and guilds. Differential vulnerability of species and guilds depends on degree of resource specialisation, primary foraging substrate, population resilience as well as dispersal ability, among other factors ( De Lima et al., 2013;Menon et al., 2019;Srinivas and Koh, 2016;Newbold et al., 2013). For example, forest specialists and insectivores tend to decrease (Menon et al., 2019) while commensal species and granivores tend to increase in abundance in intensively used landscapes (De Lima et al., 2013;Shochat et al., 2006). ...
Article
Full-text available
Land use change is the most widespread driver of biodiversity loss in densely populated tropical countries. Biodiversity loss, in turn, results in changes in functional guilds responsible for various forest ecosystem services. It is thus necessary to understand the extent and types of biodiversity loss and functional guild alteration caused by land use change in order to facilitate sustainable land use policies. Here we study the effects of land use change on forest bird species and guilds in a human-dominated landscape in the Western Himalaya, India. We carried out systematic breeding-season surveys in six land use types within moist temperate forest: natural (protected) oak forest, degraded (lightly used) oak forest, lopped (heavily used) oak forest, pine forest, cultivation and built-up sites, in two adjoining landscapes, over two consecutive years. Our study shows moderate to drastic species loss in all modified land use types in comparison to natural oak forest. Species composition in modified land use types diverged significantly from natural oak; this effect was highest in cultivation and built-up sites and least in degraded forests. Compositional change in modified land uses occurred due to partial replacement of forest specialists with commensals and open country species, whereas abundance of forest generalists was relatively constant across the gradient. We also find a steep decline in the abundance of functional guilds such as pollinators, and insectivorous pest controllers in all modified land uses in comparison to natural oak forest. Our results have important implications for conservation in biodiverse mountain landscapes with significant human imprint. In particular, (a) low faunal diversity in monocultures and urban sites (b) drastic (50% loss or more) loss of forest specialists, pollinators and insectivores in degraded forests, monocultures and urbanised sites; and (c) the potential for degraded forest as refugia for forest species, are findings that can be globally applied to land use and conservation planning in human-dominated landscapes.
... Loss of terminal branches and canopy due to firewood and fodder collection directly affects food availability for birds that forage in the canopy and on thinner branches 54 . Studies in dry deciduous and tropical thorn forest of Rajasthan 55 as well as Himalayan oak forests 56 have found that reduced canopy cover, tree height, understorey density and tree basal area result in low bird diversity and composition. ...
... The causes of forest degradation may vary, but the implications for birds are clear. One evident impact is a reduction in species richness and overall abundance in degraded forest in comparison with protected forest [55][56][57] . Further, species composition also changes, mainly due to the decline of forest specialists, large-bodied frugivores, and understorey insectivores, as seen in the studies listed above. ...
Chapter
Full-text available
The chapter discusses some of the major known human-caused threats to birds. - Long term trends in bird species
... Each quadratic plot was established 15 m from the center of the bird sampling point and at 120 degrees from each other. This method is commonly used for vegetation surveys (Rajpar and Zakaria 2011; Menon et al. 2019). In each quadratic plot, we recorded the number of plant species, and visually estimated percent cover of tree, shrubs, herbs, short grasses (height < 1 m), long grasses (height > 1 m), shallow water (depth < 1 m), and deep water (depth > 1 m). ...
... To measure each sample plot's distance to human settlement, we first plotted the coordinates of our sampling points in Google Earth and then we measured the straight-line distance from each plot to the nearest human settlement by using "Ruler Tools". All environmental variables recorded in the three quadratic plots were averaged as a single value for each bird sampling point (Rajpar and Zakaria 2011; Menon et al. 2019;Han et al. 2021;Lee 2022;Schmidt et al. 2022). ...
Article
Full-text available
Wetland ecosystems host an extensive number of avian species and play therefore a key role in biodiversity conservation. However, avifauna in wetlands is severely impacted by the anthropogenic transformation of natural habitats into other land uses. Understanding how habitat changes influence avian community dynamics is crucial for effective management and conservation of bird habitats. Here, we assessed spatio-temporal variation in taxonomic, functional, and phylogenetic diversity, and assembly structures of the bird community in the Indawgyi Wetland Ecosystem in Myanmar. Bird surveys were seasonally conducted at 120 sample plots, which were equally distributed among four habitat types subject to different level of human influences (natural lake habitat, seasonally flooded grasslands, riparian forest, and agricultural land). Across habitat types, functional and phylogenetic diversity were the highest in the lake habitat, especially during the migration season, and the lowest in the cultivated habitat. Our results indicated over-dispersed functional and phylogenetic structures in the lake habitat, with clustered structures in the remaining habitats. Diversity of species important for conservation was also higher in the lake habitat and in areas far away from human disturbances. Spatial variation of bird community diversity suggests that conservation efforts in this ecosystem should concentrate more on the lake habitat and associated grassland habitats. Moreover, our results suggest the need for habitat restoration in riparian forests and increased sustainable agricultural practices in order to improve the contribution of these habitats to the diversity in the avifauna community. Our study highlighted the importance of integrating functional and phylogenetic dimensions into biodiversity analyses providing broader ecological insights for conservation.
... Intensive anthropogenic disturbances in native forests, such as logging and livestock, generate changes in the forest structure that contribute to fragmentation, loss of habitat and biodiversity, and reduction of ecosystem services (e.g., Fynn et al., 2016;Jamhuri et al., 2018). High intensity silviculture degrades the composition and availability of structural attributes of forests such as understory and canopy cover, woody debris, basal area and soil depth (e.g., Mishra et al., 2004;Liira et al., 2007;Zamorano-Elgueta et al., 2012;Ibarra and Martin, 2015;Menon et al., 2019). The loss of structural attributes caused by intensive anthropogenic disturbances is known to affect species (e.g., birds, mammals and invertebrates) that depend on them for their survival (Caviedes and Ibarra, 2017;Lencinas et al., 2018). ...
... Therefore, in silvopastoral systems, thinning has been used to increase understory forage supply for livestock, while maintaining the presence and benefits of overstory trees. Nevertheless, even lowintensity thinning can alter some key structural habitat attributes, like understory composition, remnant basal area, and canopy cover complexity, which deeply affects birds and other animals that depend on these attributes for their survival (e.g., Menon et al., 2019). ...
Article
Low intensity silviculture has been used to decrease the impact of forest harvesting, for example, on bird species and structural diversity. The objective of this work was to analyse the long-term effect of thinning on bird communities of Nothofagus antarctica forests in Tierra del Fuego (Argentina), compared with unthinned forests at two different locations. Thinning was performed 15 and 50 years ago at each location (ranches), therefore we also evaluated other common forest habitat types to differentiate these effects (location and time). We sampled four habitat types associated to overstory canopy cover (CC) categories: thinned (35–65% CC), and three unthinned forests (open with <35% CC, closed with 65–85% CC, and very closed with >85% CC), totalling 32 sampling sites (2 ranches × 4 canopy cover × 4 replicates). Bird assemblages’ structure and functional traits (e.g., richness, density, trophic groups, use of strata) were surveyed during two consecutive summers (2017–2020) at each site. We also characterized habitats by: (i) forest structure and ground cover (e.g., basal area, debris, and saplings); and (ii) food availability, considering understory plants consumed by birds (e.g., plant richness, grasses and dicots cover) and arthropods (e.g., total abundance). We evaluated the effect of CC, ranch, time, habitat and food availability by Generalised Linear Mixed Models and multivariate analyses (Multiple Response Permutation Procedure, Canonical Correspondence Analysis). In thinned forests, some bird structure and functional traits remained similar to closed forests; however, thinning increased bird species richness, being more similar to open forests. Effect of time could not be detected. CC and ranch were the factors that better described bird community structure, while forest structure, ground cover and food availability (e.g., dominant height, basal area, proportion of Hymenoptera) were the main drivers of most functional traits. The whole bird assemblage was better explained by 4–6 habitat structure and food availability variables depending on location (ranch). Results suggest thinning will benefit bird conservation if thinned forests maintain characteristics of mature forests (e.g., basal area > 40 m²/ha, shrub cover > 5%).
... Intensive anthropogenic disturbances in native forests, such as logging and livestock, generate changes in the forest structure that contribute to fragmentation, loss of habitat and biodiversity, and reduction of ecosystem services (e.g., Fynn et al., 2016;Jamhuri et al., 2018). High intensity silviculture degrades the composition and availability of structural attributes of forests such as understory and canopy cover, woody debris, basal area and soil depth (e.g., Mishra et al., 2004;Liira et al., 2007;Zamorano-Elgueta et al., 2012;Ibarra and Martin, 2015;Menon et al., 2019). The loss of structural attributes caused by intensive anthropogenic disturbances is known to affect species (e.g., birds, mammals and invertebrates) that depend on them for their survival (Caviedes and Ibarra, 2017;Lencinas et al., 2018). ...
... Therefore, in silvopastoral systems, thinning has been used to increase understory forage supply for livestock, while maintaining the presence and benefits of overstory trees. Nevertheless, even lowintensity thinning can alter some key structural habitat attributes, like understory composition, remnant basal area, and canopy cover complexity, which deeply affects birds and other animals that depend on these attributes for their survival (e.g., Menon et al., 2019). ...
Article
Low intensity silviculture has been used to decrease the impact of forest harvesting, for example, on bird species and structural diversity. The objective of this work was to analyse the long-term effect of thinning on bird communities of Nothofagus antarctica forests in Tierra del Fuego (Argentina), compared with unthinned forests at two different locations. Thinning was performed 15 and 50 years ago at each location (ranches), therefore we also evaluated other common forest habitat types to differentiate these effects (location and time). We sampled four habitat types associated to overstory canopy cover (CC) categories: thinned (35–65% CC), and three unthinned forests (open with <35% CC, closed with 65–85% CC, and very closed with >85% CC), totalling 32 sampling sites (2 ranches × 4 canopy cover × 4 replicates). Bird assemblages’ structure and functional traits (e. g., richness, density, trophic groups, use of strata) were surveyed during two consecutive summers (2017–2020) at each site. We also characterized habitats by: (i) forest structure and ground cover (e.g., basal area, debris, and saplings); and (ii) food availability, considering understory plants consumed by birds (e.g., plant richness, grasses and dicots cover) and arthropods (e.g., total abundance). We evaluated the effect of CC, ranch, time, habitat and food availability by Generalised Linear Mixed Models and multivariate analyses (Multiple Response Permutation Procedure, Canonical Correspondence Analysis). In thinned forests, some bird structure and functional traits remained similar to closed forests; however, thinning increased bird species richness, being more similar to open forests. Effect of time could not be detected. CC and ranch were the factors that better described bird community structure, while forest structure, ground cover and food availability (e.g., dominant height, basal area, proportion of Hymenoptera) were the main drivers of most functional traits. The whole bird assemblage was better explained by 4–6 habitat structure and food availability variables depending on location (ranch). Results suggest thinning will benefit bird conservation if thinned forests maintain characteristics of mature forests (e.g., basal area > 40 m2/ha, shrub cover > 5%).
... These forests form a low canopy of around 5 to 6 m in height, and generally host different bird communities when compared to adjacent grasslands, as forest birds are not adapted to disperse through open areas (Barros et al. 2019). Dispersion of forest birds toward open areas can be facilitated when forest-like environments become more common in a landscape with grassland afforestation (Öckinger et al. 2012;Barros et al. 2019;Menon et al. 2019). This suggests that (1) the ecological processes producing nestedness will have a greater contribution to bird community assembly in tree plantations than processes producing turnover (Filloy et al. 2010;Dias et al. 2013;Corbelli et al. 2015;Jacoboski et al. 2016), and (2) the nestedness of birds in tree plantations relative to natural forests should increase with increasing cover of tree plantations in the landscape (Norfolk et al. 2017;Karp et al. 2018). ...
... Ecological communities are getting increasingly similar in composition with the dissemination of generalist and invasive species (McKinney and Lockwood 1999; Fig. 3 Contribution of turnover (β.SIM) and nestedness (β.SNE) to total beta-diversity (β.SOR) of bird communities, considering multi-site beta-diversity of all birds (black; regarding hypothesis 1) and forest birds (gray; regarding hypothesis 2) across different combinations of habitats Dornelas et al. 2014). Preventing the extensive modification of grassy landscapes into tree plantations is the way to prevent biodiversity losses and biotic homogenization in grassy landscapes (Menon et al. 2019), such as those found in southern Brazil. While patches of native forests close to tree plantations are important for maintaining forest bird diversity in forested landscapes (Gilroy et al. 2015;Prescott et al. 2016), this does not apply for grassy landscapes (Filloy et al. 2010;Corbelli et al. 2015). ...
Article
Full-text available
The conversion of natural grasslands into tree plantations has reduced the extent of natural habitats in southern Brazil, altering bird composition due to local species extinction and colonization. Tree plantations represent a new land use in the region and are within a mosaic of altered and native vegetation. We investigated whether bird composition of tree plantations immersed within a grassy landscape consists of a nested subset of species from adjacent riparian forests. We sampled birds in riparian forests and in eucalyptus plantations at two stages of development using the point count method. We partitioned beta-diversity into nestedness and turnover components to detect the strength of local extinction and colonization processes, respectively, in determining variation in composition among native forests and intermediate and old-aged plantations considering all birds together and only forest-specialist birds. We then used linear models to test the effect of land use on the pairwise turnover and nestedness that each plantation presents relative to native forests. We recorded 72 bird species, of which 62, 25, and 22 species were found in riparian forests, intermediate, and old-aged plantations, respectively. Turnover predominated in beta-diversity partitioning—whether all birds or just forest-specialist birds were analyzed—showing that the bird composition of tree plantations might not depend on adjacent forests, but instead on sparse resource availability within tree plantations. Finally, we found lower bird turnover for plantations relative to native forests with increasing cover of tree plantations in the landscape. Large extents of tree plantations in the landscape, therefore, homogenize bird composition across sites.
... These forests are important for the maintenance of biodiversity and meeting the biomass demand of local people (Negi et al. 2012), but they are lesser known for their avifauna. The state hosts more than 50% of India's bird species (Mohan and Sondhi 2015), but bird-related studies in KSL-India (Pithoragarh district) have been few (Brooks 1869;Walton 1900;Whymper 1902aWhymper , 1902bKoelz 1954;Tak andSati 1994, 2006;Tak 1995;Sultana and Khan 2000;Raza 2005;Elsen et al. 2017) in comparison to nearby districts of the Kumaon region (Irby 1861;Sharpe 1890;Osmaston 1916;Hudson 1930;Ganguli 1966;Sridharan 1974;Narang and Lamba 1979;Yahya 1990;Sultana 2007;Ahmed 2010;Bhatt and Joshi 2011;Palita et al. 2011;Joshi et al. 2012;Shahabuddin et al. 2017;Menon et al. 2019). We have selected different community-managed lands in the lower reaches of KSL-India to document the avifauna, as these areas are relatively unexplored in comparison to the upper reaches. ...
... We maintained a distance of 150-200 m between each point to avoid double counting. All species seen or heard within 15 minutes were recorded (Menon et al. 2019). For MacKinnon species richness, we prepared a list of 20 distinct species by walking on existing trails in the community-managed forests and cultivated lands and once 20 species was reached, another list was prepared (Ahmed et al. 2019). ...
Article
Full-text available
In the Indian Himalayan region, community-managed lands such as community-managed forests and agriculture lands play an important role in conserving native biodiversity. Our avifaunal surveys done between 2013 and 2016 recorded 205 species belonging to 52 families. Two species were first records from Pithoragarh district. Six species are classified as Threatened and five as Near Threatened in the IUCN Red List. Six are Schedule-I species under the Indian Wildlife (Protection) Act, 1972. In total, 63 migratory (local/altitudinal and long-range) and 81 Himalayan endemic species were observed. Overall, our observations reveal a niche providing both transient and perennial havens for resident and migrant avifauna in our study site's landscape. Our findings suggest that despite human persistence in the landscape, diversity within avifaunal guilds is rich in the community-managed lands. We recommend further research to focus on understanding the factors governing the bird distribution and co-occurrence in the landscape.
... Thus, saving low and mid-elevation Himalayan habitats is critical not only for saving species resident at those elevations but also for safeguarding the populations of high elevation birds that spend up to 8 months of the year there in the winter (Menon et al., 2019;Nocedal, 1994;Vázquez-Reyes et al., 2017). High elevation breeders may thus be affected by both local-scale habitat destruction at low elevation and global scale changes such as climate warming in the high elevation breeding ranges. ...
Article
Aim Elevational migration is a globally ubiquitous animal behaviour. Understanding the mechanisms that drive variation in elevational movement can help explain the evolution of this widespread animal behaviour and its role in shaping montane life history. We examine the role of thermal regime (the intra‐annual variation in temperature experienced by a species), dispersal ability and diet in explaining the extent of elevational movements. Location Eastern and Western Himalayas. Time Period 2011–2022. Major Taxa Studied Birds. Methods We used community science data from eBird to acquire checklist‐based observations of birds and used comprehensive data cleaning procedures and randomization tests to produce estimates of seasonal elevational shifts for 302 species of Himalayan birds. Using these data, we ran phylogenetic least squares regressions (PGLS) to test if the extent of elevational shift is driven by thermal regime, dispersal ability and diet. Results Most Himalayan birds (up to 65%) showed downslope shifts in the winter, although some (5%‐10%) low elevation species shifted upslope. Elevational shift was negatively associated with a species' thermal regime. Species that showed the greatest elevational shifts in both eastern and western Himalayas moved within the narrowest intra‐annual temperature regimes, but did not match their breeding range temperatures as closely as possible. Diet influenced elevational shift in both eastern and western Himalayas, while dispersal ability did not drive elevational shifts. Main Conclusions Species that show the biggest elevational shifts track thermal regimes most closely. However, in addition to tracking thermal regimes, diet and potentially habitat availability/preferences may drive seasonal elevational shifts. Our results show convergent evolution of elevational shifts across clades. Low elevation habitats are important not only for conserving low elevation birds but also for conserving wintering sites of most high elevation breeders.
... This has implications in terms of biodiversity conservation, local livelihoods and ecosystem services (Joshi et al. 2013). Usually, the oak stands have a richer understorey that harbour a greater bird diversity than the pine stands with very little understorey (Menon et al. 2019). Oak forests are also important for the livelihood of the local people, as they rely on these forests for cattle grazing, cattle fodder and leaf litter for mulching (Naudiyal et al. 2017, Shahabuddin andThadani 2018). ...
Article
Full-text available
Pine forests and oak forests co-occur in many places throughout the northern hemisphere. Both the species interact with each other and both are adapted to landscapes with frequent fires. In recent years, there has been a concern among ecologists and conservationists that the mid-elevation of Western Himalaya, India is witnessing an invasion by a native pine 'chir' (Pinus roxburghii) into the native oak 'banj' (Quercus leucotrichophora) forests. Many hypotheses have been proposed for explaining this shift in the local vegetation pattern, including climate warming, opening of oak canopies due to excessive fuelwood extraction and changes in fire frequencies. In this thesis, I set out to test one of these hypotheses-fire promotes chir pine to invade into banj oak forests. I arrived at a possible mechanism by which chir pine might be invading into banj oak based on inputs from researchers familiar with the landscape, from the local people and by literature review. I proposed that the fire opens up the canopy of the oak trees and changes the soil conditions, which might help chir pine to establish in the otherwise low-light conditions of the banj oak forests. Based on this hypothesis, I predicted that if there is a gradual invasion by pine into oak forests, the average age of pine individuals will be lower near the invasion interface between an oak and pine forest as compared to the pine trees away from the invasion interface and further within the oak forests. I also predicted that, if fire promotes pine invasion, the above effect would be most pronounced at interfaces with high fire frequency as compared to unburnt interfaces and transects with low fire frequency. To test for signs of invasion, I laid transects perpendicular to the interface between the two forest types and measured the girth of all chir pine and banj oak trees in the transect. For a subset of the transects, I measured the ages of all the pine trees in the transect from tree cores, which were extracted using an increment borer. Through the metrics I measured, I was unable to detect evidence of fire promoting pine tree invasion into oak patches. However, I found that fires led to an increase in oak seedling numbers within oak forests, for a short period immediately after a fire event. After the initial spike in seedling numbers in the burnt oak forests, which lasted for a few years, I found that oak seedling regeneration in oak forests starts to reduce. Pine seedlings did not show any response to fire. Hence, my study indicates that the only way in which fire might be facilitating pine invasion is by reducing the level of oak regeneration. There are several possible reasons why I might not have found evidence of the role fire plays in the invasion-the actual absence of an invasion, a mechanism of invasion different from what I hypothesized, or a mismatch between the scale (spatial grain) of the study and the phenomenon under investigation. Too small a sample size to detect the phenomenon or lack of accounting other variables that could affect oak and pine growth and regeneration are other possible reasons for the lack of evidence for invasion.
... Vegetation structure can play an important role in determining various life-history strategies and ecologies of species. For example, in addition to affecting overall resource availability, vegetation density and complexity can influence prey visibility, foraging success, predation risk, nest and roost sites, and consequently, habitat selection by birds (Whelan 2001, Raman 2006, Lebbin 2007, Socolar et al. 2013, Menon et al. 2019. The vegetation structure of bamboo could help in creating a less complex habitat than rainforest, as bamboo contains more homogenous leaf structures, providing a consistent and simpler search image for birds. ...
Preprint
Full-text available
Bamboos (Poaceae: Bambuseae) are a unique and diverse group of plants (> 1500 species) that are found in tropical and subtropical regions of the world. Various birds, mammals, and insects use bamboo either directly or indirectly, and some species are obligate bamboo specialists. For instance, several species of Neotropical birds are found in bamboo alone. However, the mechanisms underlying dependence on/associations with bamboo are almost entirely unknown. I studied bird communities in bamboo and rainforest across two seasons in the Eastern Himalaya, where I explored a possible mechanism for bird associations with bamboo - dietary resource specialization. I calculated use of bamboo versus rainforest by bird species and described the structure and composition of the bird and arthropod communities in both habitats and seasons. I provide the first systematic evidence of bamboo specialist bird species from the Eastern Himalaya. Although the species richness of birds and arthropods in both habitats and seasons did not vary starkly, I found that the composition of bird and arthropod communities in both habitats and both seasons to be distinct. Interestingly, I found arthropod communities in different substrates of bamboo to also be distinct. Bird specialization in bamboo in the Eastern Himalaya could be because of their dietary specialization to the unique arthropods found in bamboo. The results from this study emphasise the importance of bamboo in the Eastern Himalaya and provide baseline information that might aid in conservation.
... In particular, streets with higher number of native trees are found to support a richer community of birds (Ikin et al., 2013). Further, tree characteristics such as canopy cover, canopy volume and tree height can significantly affect tree utilization by birds (Menon et al., 2019;Murgui 2007;Pena et al., 2017), which then affect their foraging on fruiting trees. ...
Article
Full-text available
Street trees have been used as a means of mitigating the negative effects of urbanization on biodiversity, particularly bird fauna. Despite their widely acknowledged benefits for birds, studies so far have been largely limited to relatively coarse scales, with an understanding of the role of local environments and individual tree characters lacking. We studied the patterns of bird visitation at individual street Ficus (fig) trees, providers of keystone resources in tropical landscapes, in Delhi, India, and their drivers at different scales (tree characteristics, local and landscape variables). Three common fig species were surveyed for bird visitors across 3 sites with varying urban patterns. Fig trees were found to be a relatively common street tree choice, and the 106 trees surveyed were visited by 29 bird species, including 7 obligate frugivores. We found that reducing green cover in surrounding landscape and increasing noise did not deter birds from visiting these trees. Instead, variables at finer scales like tree canopy diameter, tree species and local resource density had sizable and significant effects on both species richness and abundance of bird visitors. Our results highlight how bird assemblages, guilds and individual species respond differently to a range of ecological variables, and an understanding of these responses at different scales is useful for maximising the value of street trees for urban birds. Thus, coarse-scale studies can provide insights into bird diversity of city landscapes, but micro-scale studies are important in helping make fine scale management decisions, like selection of street trees.
... The gujjar settlements and villages in and around depend on the forests for fuelwood and fodder, grass collection, dry leaf collection, honey, fishing. Extraction of fuelwood and grazing causes changes in the landscape (Chhetri et al., 2005;Singh et al., 2000;Kaushik et al., 2012;Shahabuddin, Kumar and Verma, 2006;Menon, Sridhar and Shahabuddin, 2019). Moreover there is National Highway 74 which leads to wildlife road kills. ...
Article
Full-text available
A survey of avifauna was carried out in Jhilmil Jheel Conservation Reserve (JJCR) of Haridwar Forest Division, Uttarakhand during 2018-2020. Point count method was used to count birds in six habitats viz., plantation, mixed forest, riverine habitat, scrub forest, grasslands and agriculture field. In total, 170 species of birds representing 16 orders and 64 families were recorded. The dominant order was Passeriformes, while the dominant foraging guild was insectivore birds. Most of the bird species were resident. The overall bird species diversity was 4.126. JJCR harbours 10 species of globally threatened avifauna including 3 Critically Endangered, 3 Endangered, and 4 Vulnerable species; in addition, the reserve also has 8 species of Near Threatened birds. The present documentation of avian community structure would help in developing conservation plan of this IBA.
... These results suggest that different bird species respond to habitat characteristics at different spatial scales (local stand vs. landscape) as has also been observed by other authors [16,70]. Forest specialist species were more related to forest structure variables (canopy cover), as was observed by Muhamad et al. [72] and Menon et al. [73], and other habitat characteristics at the local stand level (understory plants and abundance of arthropofauna), as was observed be Vergara and Schlatter [74], Stratford and Stouffer [75], and Cahill et al. [76]. Therefore, these species may be more sensitive to activities (e.g., clear cutting, thinning) that result in a reduction of canopy cover below 80% and decreasing abundance of arthropods below 1000 ind per trap. ...
Article
Full-text available
Different variables operate simultaneously at different spatial scales, influencing community composition and species distribution. This knowledge could improve management and conservation practices in managed menaced forests. The objective of this work was to determine the influence of landscape and stand variables on the bird assemblage of the managed Nothofagus antarctica forest of Tierra del Fuego (Argentina). We used data from bird point counts (three or four censuses during middle summer of two consecutive years) located at 48 sites distributed at four ranches. At each site, we extracted landscape variables with Fragstat software from the forest patches, the cover classes, and the whole landscape. We also evaluated local stand characteristics, such as forest structure, ground cover, and food availability, including understory plant cover usually consumed by birds and available arthropods. Data were evaluated by detrended and canonical correspondence analyses. We found that landscape configuration (e.g., forest patch shape) and local stand variables (e.g., canopy cover) influenced bird assemblage more than landscape composition. Moreover, bird functional groups responded differently to different spatial scale variables (e.g., forest specialist species were associated with forest structure, but species that use low strata to nest and feed were associated with landscape configuration variables), demonstrating the importance of using multiple spatial scales to better understand bird species requirements. The combination of practices that promote some local characteristics (e.g., high canopy cover) and more complex landscape configurations could simultaneously favor different bird species groups and improve the effectiveness of management and conservation strategies.
... In particular, streets with higher number of native trees are found to support a richer community of birds (Ikin et al. 2012). Further, tree characteristics such as canopy cover, canopy volume and tree height can signi cantly affect tree utilization by birds (Menon et al 2019;Murgui 2007;Pena et al. 2017), which then affect their foraging on fruiting trees. ...
Preprint
Full-text available
Street trees have been used as a means of mitigating the negative effects of urbanization on biodiversity, particularly bird fauna. Despite their widely acknowledged benefits for birds, studies so far have been largely limited to relatively coarse scales, with an understanding of the role of local environments and individual tree characters lacking. We studied the patterns of bird visitation at individual street Ficus (fig) trees, providers of keystone resources in tropical landscapes, in Delhi, India, and their drivers at different scales (tree characteristics, local and landscape variables). Three common fig species were surveyed for bird visitors across 3 sites with varying urban patterns. Fig trees were found to be a relatively common street tree choice, and the 106 trees surveyed were visited by 29 bird species, including 7 obligate frugivores. We found that reducing green cover in surrounding landscape and increasing noise did not deter birds from visiting these trees. Instead, variables at finer scales like tree canopy diameter, tree species and local resource density had sizable and significant effects on both species richness and abundance of bird visitors. Our results highlight how bird assemblages, guilds and individual species respond differently to a range of ecological variables, and an understanding of these responses at different scales is useful for maximising the value of street trees for urban birds. Thus, coarse-scale studies can provide insights into bird diversity of city landscapes, but micro-scale studies are important in helping make fine scale management decisions, like selection of street trees.
... las cortas, la ganadería, la introducción de pasturas), degradan la composición y la disponibilidad de los atributos estructurales de los bosques como el sotobosque, la cobertura de copas, los residuos leñosos gruesos, la presencia y el estado de descomposición de los tocones, el área basal y la profundidad del suelo, entre otras características (ej. Mishra et al. 2004, Liira et al. 2007, Zamorano-Elgueta et al. 2012, Ibarra y Martin 2015, Menon et al. 2019. Se sabe que la pérdida de estos atributos afecta la biodiversidad (ej. ...
Thesis
El uso ganadero de los bosques de Nothofagus antarctica de Tierra del Fuego (Argentina) ha sido históricamente extensivo y poco planificado, y usualmente basado en la reducción de cobertura arbórea mediante cortas para aumentar la producción de forraje bajo su dosel. El objetivo de esta tesis fue analizar estructura y rasgos funcionales de las comunidades de aves terrestres, diurnas y residentes estivales (principalmente paseriformes), en diferentes estados del bosque de N. antarctica evaluando el efecto de variables ambientales a escala local y de paisaje, así como el potencial uso de las aves como indicadoras de impactos para mejorar las propuestas de estrategias de manejo foresto-ganadero existentes. Este trabajo se realizó en 4 Estancias (Los Cerros, Rolito, Las Hijas y Cabo San Pablo) ubicadas en el centro y este de la Isla Grande de Tierra del Fuego (Argentina). Se estudiaron 4 tipos de bosque: un tipo con raleos (Abiertos) y tres tipos sin raleos (Muy Cerrados, Cerrados y Muy Abiertos). Las aves se estudiaron en puntos de observación fijos, donde se realizaron conteos durante los meses de enero y febrero del 2017 y 2018 en Los Cerros, 2018 y 2019 en Rolito, y 2019 y 2020 en Las Hijas y Cabo San Pablo, para caracterizar estructura (composición, riqueza, densidad, biomasa e índices de diversidad) y rasgos funcionales (grupos tróficos, uso de sustratos, tipo de nidificación y estatus migratorio). En Los Cerros y Rolito también se analizó la susceptibilidad a la depredación de nidos artificiales. Los efectos analizados fueron: a escala local, la estructura forestal (altura dominante, área basal, cobertura de copas, densidad de árboles y diámetro medio), la cobertura del suelo (sotobosque, residuos leñosos, plantas no-vasculares, renovales y suelo sin vegetación), y la oferta alimenticia, vegetal (riqueza y cobertura total, de gramíneas y de dicotiledóneas consumidas por aves) y de la artropofauna (abundancia total y proporción de los órdenes más importantes); y a escala de paisaje, área, perímetro y forma del parche; área, número de parches, índice del parche más grande y conectividad de bosques y áreas abiertas; y total de bordes y densidad de bordes. Las variables fueron evaluadas mediante modelos lineales generalizados (GLM) y generalizados mixtos (GLMM), y multivariados (PCA, MRPP, IndVal, y CCA). Se pudo identificar mayor riqueza y diversidad de especies de aves en bosques Abiertos (raleados) y Muy Abiertos, dadas por la presencia de especies de áreas abiertas o de bordes de bosque. Por otro lado, se identificaron menores densidades de omnívoros y granívoras en bosques Cerrados y Muy Cerrados, respectivamente, vinculadas a los sustratos de alimentación. El uso de los sustratos difirió entre tipos de bosque, estando el uso de sustratos bajos y copas relacionado con su disponibilidad. Mientras que el uso de ramas y fustes, y la densidad de individuos volando se asociaron a la estructura forestal (cobertura de copas y área basal, entre otras). Por otro lado, la densidad de especies que nidifican en huecos y copa abierta, así como la densidad de residentes y migradoras, también difirieron entre tipos de bosque y se asociaron a la altura dominante y a la cobertura de copas. Los bosques raleados, si bien presentaron algunas diferencias con los Cerrados y Muy Cerrados (mayor riqueza de especies, diversidad, uso de sustratos bajos, densidad de aves volando y de migradoras), fueron parecidos en otros rasgos (ej. densidad de aves que utilizan ramas y copas o que nidifican en huecos), observándose en ellos incluso especies especialistas de bosque (Pygarrhichas albogularis y Aphrastura spinicauda). Si bien no se encontraron diferencias significativas en la susceptibilidad a la depredación de nidos artificiales entre tipos de bosque, los nidos que se encontraban en bosques Muy Abiertos fueron depredados más rápido. Este estudio permitió identificar especies indicadoras de bosques Cerrados y Muy Cerrados (A. spinicauda, P. albogularis), Abiertos (Spinus barbatus) y Muy Abiertos (ej. Tachycineta leucopyga). Por lo tanto, estas especies se podrían utilizar para el monitoreo de los raleos en estos bosques. Al analizar variables de diferentes escalas espaciales (local y paisaje), se pudo observar que las mismas influyeron sobre diferentes grupos de especies. Por ejemplo, la estructura forestal (área basal, cobertura de copas) y el área del parche de bosque tuvieron mayor efecto sobre P. albogularis. Se concluye que ciertas características a nivel local (ej. mayor área basal, cobertura de copas y de renovales, y proporción de himenópteros), así como a nivel de paisaje (ej. parches de bosque grandes e irregulares, alternancia con áreas abiertas), favorecen a una mayor diversidad de aves en los bosques de N. antarctica de Tierra del Fuego. El desarrollo de propuestas de manejo forestales y silvopastoriles que preserven o favorezcan la presencia de paisajes y parches de bosque con estas características contribuiría a que el manejo de estos bosques sea más sustentable.
... 24 Consequently, studies have shown forest faunal populations, including amphibians, bats, birds and reptiles, to be sensitive to human-mediated changes in habitat structure, with species specialised in their foraging or microhabitat requirement being particularly sensitive. [25][26][27][28][29][30] Given the critical ecosystem functions provided by forest fauna -including seed dispersal, pest control and pollination 31 -human activities that modify habitat structure may have ramifying effects on forest ecosystem functioning. ...
Article
Full-text available
The Eastern Cape Province harbours 46% of South Africa’s remaining indigenous forest cover, and is one of the country’s poorest and least developed provinces. Forest resources thus represent a vital component of rural livelihoods in this region. Consequently, forest management policies aim to balance the needs of resource users with the ecological integrity of forest ecosystems. In a recent study, forest bird ranges were shown to have declined in the Eastern Cape over the past 20 years, despite increases in forest cover over the same time period, indicating that habitat degradation may be driving forest bird losses. Given that harvesting of forest products represents the primary human disturbance in forests in the Eastern Cape today, insight is needed regarding the link between resource use and habitat modification. We report on effects of harvesting of three key forest products – poles, timber and medicinal bark – on habitat structure at the ground, understorey and canopy layers in indigenous forests in the province. Harvest activities had considerable impacts on habitat structure, depending on the nature and extent of harvesting. Bark and timber harvesting resulted in canopy gaps, whereas pole harvesting reduced tree density, resulting in understorey gaps. Overall, harvest activities increased the frequency of canopy disturbance, and density of understorey layer foliage. Unsustainable bark harvesting practices increased the mortality rate of canopy trees, thereby increasing dead wood availability. By providing insight into human-mediated habitat modification in forests of the Eastern Cape, this study contributes to the development of ecologically informed sustainable resource management policies. Significance: • Unregulated harvesting of forest products in state-managed indigenous forests of the Eastern Cape results in habitat modification. • The nature and extent of habitat modification is dependent on the type and intensity of resource use, indicating that resource use may be sustainably managed. • Timber and medicinal bark harvesting activities result in canopy disturbances, thereby altering natural canopy gap dynamics, with concomitant impacts on understorey habitat structure. • Changes in forest habitat structure associated with high levels of resource use are likely to have ramifying effects on forest biodiversity.
Article
Full-text available
Purpose of Review Biodiversity values frequently encounter challenges from developmental needs despite having strong forest and wildlife laws in developing countries like India. Landscape ecology offers the relevant scientific backstopping and sophisticated tools to support conservation of several species. To aid the future development of landscape ecology in India within current and emerging contexts, we reviewed the spatio-temporal and thematic trends in the published research involving forest and wildlife conservation. Recent Findings Spatial modelling and land use land cover change assessments have been well established conceptually and methodologically, but an increase in studies involving impact of climate change on species habitat suitability is comparatively very recent. Thematic research gaps in this field include impact of scale on ecological processes, and uncertainty and error quantification in modelling. Dedicated studies on characterisation of biodiversity and its dynamics in biogeographic transition zones can scientifically inform management of forest and wildlife. Summary The review of 494 peer-reviewed articles published between 1994 and 2021 showed an increase in published research on landscape ecology over time. We found that the studies were dominated by the ‘Pattern–Process–Scale’ related questions and spatially clustered in the Western Ghats (biodiversity hotspot) and Uttarakhand state. Considerable research efforts are required in riverine and coastal ecosystems. Nevertheless, the increasing trend of research across themes and regions is a positive indicator of the growing role of landscape ecology in forest and wildlife management in India.
Article
Full-text available
The main target of this research is to investigate the Avian Specimens that are found in Tuensang District areas, Nagaland, north east India. Tuensang district is one of the largest eastern most district in Nagaland and is rich in both flora and fauna diversity. Through this research, 13 avian Specimens were identified based on their morphologically and systematically different. The Avian Species diversity vary from different Colour Morphologically. The Anorrhinus tickelli (Blyth, 1855), Asarcornis scutulata (S. Muller, 1842) and Aceros nipalensis (Hodgson, 1929) were reported from the present study which were found to be declared as near-threatened, endangered and vulnerable species by the IUCN 3.1.
Article
Full-text available
Despite the fact that tropical dry forests are being exploited on a large scale for various forest products, there has been limited evaluation of the accompanying ecological impacts. In particular, there is no information on the effects of widespread biomass extraction such as grazing and firewood collection. This study was carried out in Sariska Tiger Reserve in northern India, to investigate the effects of biomass extraction on forest vegetation composition, diversity and structure.
Article
Full-text available
In this paper, we present an estimate of the predation impact of the global population of insectivorous birds based on 103 (for the most part) published studies of prey consumption (kg ha⁻¹ season⁻¹) of insectivorous birds in seven biome types. By extrapolation—taking into account the global land cover of the various biomes—an estimate of the annual prey consumption of the world’s insectivorous birds was obtained. We estimate the prey biomass consumed by the world’s insectivorous birds to be somewhere between 400 and 500 million metric tons year⁻¹, but most likely at the lower end of this range (corresponding to an energy consumption of ≈ 2.7 × 10¹⁸ J year⁻¹ or ≈ 0.15% of the global terrestrial net primary production). Birds in forests account for > 70% of the global annual prey consumption of insectivorous birds (≥ 300 million tons year⁻¹), whereas birds in other biomes (savannas and grasslands, croplands, deserts, and Arctic tundra) are less significant contributors (≥ 100 million tons year⁻¹). Especially during the breeding season, when adult birds feed their nestlings protein-rich prey, large numbers of herbivorous insects (i.e., primarily in the orders Coleoptera, Diptera, Hemiptera, Hymenoptera, Lepidoptera, and Orthoptera) supplemented by spiders are captured. The estimates presented in this paper emphasize the ecological and economic importance of insectivorous birds in suppressing potentially harmful insect pests on a global scale—especially in forested areas. Electronic supplementary material The online version of this article (10.1007/s00114-018-1571-z) contains supplementary material, which is available to authorized users.
Article
Full-text available
The banj oak (Quercus leucotrichophora) -chir pine (Pinus roxburghii) forest zone (1500–2200 m asl) of the Western Himalaya is a biodiversity-rich habitat that has undergone considerable modification and conversion over the last 20 years. Yet, there is little systematic information on its avifauna, particularly in the context of the observed impacts of global warming, land use change, forest modification, and fragmentation. In this study, we inventory the birds of this forest association based on intensive field studies carried out at 42 sites (in six geographical clusters) in the Nainital, and Almora Districts of Uttarakhand, along with collecting data on abundance status, breeding, habitat preferences, and endemism status. We recorded a total of 136 species over four years of study across these sites. Based on our observations, 104 species (76%) are likely to be breeding. The large number of broad-leaved forest specialists (35), primarily forest species that are relatively adaptable (69), and Himalayan endemics (51) recorded during the study indicates the high conservation value of this forest association. Based on our observations, and the existing literature, we suggest that the 19 Himalayan endemic species that are also oak forest specialists, are likely to be endangered due to the concordant threats of habitat degradation, fragmentation, and climate change.
Article
Full-text available
This review summarizes the current state of knowledge on pine and oak forest dynamics in the mid-montane central Himalayan forest and the ecosystem services associated with these vegetation types. Forest ecosystems play a crucial role in the livelihood of the central Himalayas as well as the adjacent plains, providing a number of tangible and intangible ecosystem services, at each stage of succession. The successional sequence starts from warm temperate grasslands, followed by early successional pine forests, mid-successional pine-oak mixed forests and eventually culminating in a late successional oak community. This successional sequence is considerably influenced by disturbances like fire, grazing, and lopping, which maintain the vegetation types in their current form and can act as potential drivers of change. Fire and grazing in grasslands and pine forests inhibit the successional process by hindering the establishment of pioneer and late successional species, respectively. Potential land-cover changes with forest succession can lead to changes in ecosystem services supply. We found that the number of ecosystem services associated with these vegetation types increase from early to late successional community. Current management approaches fail to include the dynamic nature of vegetation, which is essential for maintenance of ecosystem service supply. In conclusion, the trade-offs between ES of global (biodiversity and carbon) and local importance (fuel wood and fodder) have to be examined carefully in order to have effective conservation and management plans for the region.
Chapter
Full-text available
We surveyed birds of the forest interior, forest margin and human-dominated countryside habitats in the Pacific low-lands of the Golfo Dulce region in the vicinity of the " Tropenstation La Gamba ". Species richness was significantly higher at the forest margin compared to forest interior and human-modified habitats. Only a small proportion of species (8.8%) were recorded in all three habitat types. The majority of species were recorded only in one (41.9%) or two habitat types (49.3%). The lowest faunal similarity and thereby highest beta diversity was observed between forest interior and human-dominated habitats. The higher similarities between forest margins and the two other habitat types emphasised their role as ecotones characterised by a pronounced overlap of species from forested and (semi-)open habitats. As demonstrated by various examples, all three habitat types have characteristic species reaching their highest abundances in the forest interior, at forest edges and in human-dominated habitats , respectively. Relative species richness and abundance of range-restricted species (Central and northern South American distribution or smaller ranges) was highest in the forest interior and decreased towards forest margins and human-dominated habitats. Extremely widespread species (e.g. New World distribution) were not recorded in the forest interior but represented a substantial proportion of species and individuals recorded at the forest margin and particularly in human-dominated habitats. While winter visitors were regularly recorded at the forest margin and in human-dominated habitats, they were completely absent from the forest interior. The relative importance of feeding guilds differed between the three different habitats. The most obvious changes were observed in purely insectivorous birds, in birds feeding predominantly on seeds, in omnivores, and in scavengers. While the relative abundance of insectivorous birds was 2-3 times higher in the forest than in human-dominated habitats and at the forest margin, the mean number of recorded insectivores per observation unit was lowest at the forest margin but reached similar values in forest interior and human-dominated habitats. The abundance of granivores, omnivores and scavengers increased conspicuously from forest interior towards forest margin and (semi-)open habitats. Although human-dominated habitats of the humid Pacific lowlands in Costa Rica can be characterised by a species-rich avifauna, their potential conservation value is limited because they do not support the majority of range-restricted species. Furthermore, our data indicate that ecological services provided by birds most likely change significantly as response to deforestation.
Article
Full-text available
We developed an index of biotic integrity based on bird communities in the central Appalachians. As one component of the U.S. Environmental Protection Agency, Environmental Monitoring and Assessment Program's (EPA-EMAP) Mid-Atlantic Highlands Assessment (MAHA), the index is intended to indicate landscape-scale stressors to upland environments in the central Appalachians. The Bird Community Index (BCI) ranks bird communities according to the proportional representation of 16 behavioral and physiological response guilds. We developed the index from 34 sites in central Pennsylvania that represented a gradient of human disturbance from near pristine to degraded. Upon satisfactory demonstration that the BCI could discriminate between categories of biotic integrity identified from the human disturbance gradient, we applied it to an independent, probability-based sample of 126 sites across the MAHA area. Our assessment indicates that 16% of the area is in 'excellent' condition, 27% is in 'good' condition, 36% is in 'fair' condition, and 21% is in 'poor' condition. Sites in poor condition were dominated by either urban or agricultural bird communities, but these communities could not be numerically distinguished from each other by BCI score. Forested sites in good and excellent condition supported different bird communities and ground-level vegetation attributes but could not be separated by land cover composition alone. In general, the shift from medium to poor ecological condition defined by bird communities coincided with a shift in land cover composition from forested to nonforested.
Technical Report
Full-text available
Description Fit linear and generalized linear mixed-effects models. The models and their components are represented using S4 classes and methods. The core computational algorithms are implemented using the 'Eigen' C++ library for numerical linear algebra and 'RcppEigen' ``glue''.
Article
Full-text available
Habitat loss is the dominant threat to biodiversity and ecosystem functioning in terrestrial environments. In this study, we used an a priori classification of bird species based on their dependence on native forest habitats (forest-specialist and habitat generalists) and specific food resources (frugivores and insectivores) to evaluate their responses to forest cover reduction in landscapes in the Brazilian Atlantic Forest. From the patch-landscapes approach, we delimited 40 forest sites, and quantified the percentage of native forest within a 2 km radius around the center of each site (from 6 - 85%). At each site, we sampled birds using the point-count method. We used a null model, a generalized linear model and a four-parameter logistic model to evaluate the relationship between richness and abundance of the bird groups and the native forest amount. A piecewise model was then used to determine the threshold value for bird groups that showed nonlinear responses. The richness and abundance of the bird community as a whole were not affected by changes in forest cover in this region. However, a decrease in forest cover had a negative effect on diversity of forest-specialist, frugivorous and insectivorous birds, and a positive effect on generalist birds. The species richness and abundance of all ecological groups were nonlinearly related to forest reduction and showed similar threshold values, i.e., there were abrupt changes in individuals and species numbers when forest amount was less than approximately 50%. Forest sites within landscapes with forest cover that was less than 50% contained a different bird species composition than more extensively forested sites and had fewer forest-specialist species and higher beta-diversity. Our study demonstrated the pervasive effect of forest reduction on bird communities in one of the most important hotspots for bird conservation and shows that many vulnerable species require extensive forest cover to persist.
Article
Full-text available
Ecologists have advocated retaining various densities of canopy trees in harvest units in Pacific Northwest forests, In contrast to clear-cutting, this practice may better emulate the patterns of disturbance and structural complexity typical of natural forests in the region. Several ecological attributes, including vertebrate habitat diversity, are thought to be associated with stands of complex structure. The goal of this study was to determine bird abundance in canopy retention sites relative to other common stand types in the Pacific Northwest and to develop habitat functions for extrapolating bird abundance across current and future landscapes. We used data from five previous studies in the west central Cascades of Oregon to compare bird abundance and to develop habitat functions for forest birds across a wide range of natural and managed stand structures and ages. The 67 stands included clearcuts, retention sites, young closed-canopy plantations, mature stands, and old-growth stands. ANOVA revealed that 18 of the 23 species included in the analysis differed significantly in abundance among the stand types, with some species being primarily associated with each of the stand types. The habitat variables used to build habitat functions included tree density by size class, mean tree diameter, and variation in tree diameter. Linear, polynomial, and various nonlinear regression models were evaluated for each bird species. Significant habitat functions were generated for 17 of the 23 bird species. The analyses identified four habitat-use guilds among the 17 bird species: open-canopy; open-canopy with dispersed large trees, structurally complex closed-canopy; and structurally simple closed-canopy guilds. This study is the first in the Pacific Northwest to compare bird abundances across natural stands, traditionally managed plantations, and stands managed under ecological forestry approaches, The results suggested that canopy tree retention benefits many, but not all, of the bird species we studied, Moreover, the nonlinear responses of bird abundance revealed thresholds in tree density at which bird abundance changed dramatically. Knowledge of these thresholds allow managers to design stands for specific biodiversity objectives. The habitat functions presented here can be used to predict bird abundance based on habitat measurements derived from field data, remotely sensed data, or output from computer models of forest dynamics.
Article
Full-text available
We provide a detailed description of a fixed-radius point count method that carries fewer assumptions than most of the currently popular methods of estimating bird density and that can be used during both the nonbreeding and breeding seasons. The method results in three indices of bird abundance, any of which can be used to test for differences in community composition among sites, or for differences in the abundance of a given bird species among sites. These indices are (1) the mean number of detections within 25 m of the observer, (2) the frequency of detections within 25 m of the observer, and (3) the frequency of detections regardless of distance from the observer. The overall ranking of species abundances from a site is similar among the three indices, but discrepancies occur with either rare species that are highly detectable at great distances or common species that are repulsed by, or inconspicuous when near, the observer. We argue that differences in the behavior among species will preclude an accurate ranking of species by abundance through use of this or any other counting method in current use.
Article
Full-text available
The present study suggests that the impact of human-induced small-scale disturbances (lopping of branches and leaf litter removal) adversely impacts the functioning of banj oak (Quercus leucotrichophora, A. Camus) forests of Central Himalaya. Significantly higher (p < .001) biomass stocks, carbon sequestration rates, soil carbon, leaf area index (LAI), litter fall, and faster litter decomposition rates were observed in least human influenced (LHI) forests as compared to moderately human influenced (MHI) forests and highly human influenced (HHI) forests. Three replicate forest stands of each category were selected for the observation. The study is used as a background to suggest alternative strategies to conserve the forests, taking into account the social and economic concerns of the village community.
Article
Full-text available
Habitat loss and fragmentation alter the composition of bird assemblages in rainforest. Because birds are major seed dispersers in rainforests, fragmentation-induced changes to frugivorous bird assemblages are also likely to alter the ecological processes of seed dispersal and forest regeneration, but the specific nature of these changes is poorly understood. We assessed the influence of fragment size and landscape forest cover on the abundance, species composition, and functional properties of the avian seed disperser community in an extensively cleared, former rainforest landscape of subtropical Australia. Bird surveys of fixed time and area in 25 rainforest fragments (1-139 ha in size across a 1800 km2 region) provided bird assemblage data which were coupled with prior knowledge of bird species' particular roles in seed dispersal to give measurements of seven different attributes of the seed disperser assemblage. We used multimodel regression to assess how patch size and surrounding forest cover (within 200 m, 1000 m, and 5000 m radii) influenced variation in the abundance of individual bird species and of functional groups based on bird species' responses to fragmentation and their roles in seed dispersal. Surrounding forest cover, specifically rainforest cover, generally had a greater effect on frugivorous bird assemblages than fragment size. Amount of rainforest cover within 200 m of fragments was the main factor positively associated with abundances of frugivorous birds that are both fragmentation sensitive and important seed dispersers. Our results suggest a high proportion of local rainforest cover is required for the persistence of seed-dispersing birds and the maintenance of seed dispersal processes. Thus, even small rainforest fragments can function as important parts of habitat networks for seed-dispersing birds, whether or not they are physically connected by vegetation.
Article
Full-text available
HABITAT destruction is the major cause of species extinctions1–3. Dominant species often are considered to be free of this threat because they are abundant in the undisturbed fragments that remain after destruction. Here we describe a model that explains multispecies coexistence in patchy habitats4 and which predicts that their abundance may be fleeting. Even moderate habitat destruction is predicted to cause time-delayed but deterministic extinction of the dominant competitor in remnant patches. Further species are predicted to become extinct, in order from the best to the poorest competitors, as habitat destruction increases. More-over, the more fragmented a habitat already is, the greater is the number of extinctions caused by added destruction. Because such extinctions occur generations after fragmentation, they represent a debt—a future ecological cost of current habitat destruction.
Article
Full-text available
Treefalls gaps contribute to the habitat heterogeneity of tropical forest floors. Previous studies have shown that these gaps play an important role in plant and bird communities, however less is known about their role in arthropod communities. Using eight Malaise traps we investigated the difference in arthropod abundance of 19 taxonomic groups between gaps and understorey for 21 wk during the rainy season and 8 wk in the dry season on Barro Colorado Island, Panama. More (33.8%) arthropods were collected in gaps during the rainy season and 32.2% more in the understorey during the dry season. To assess the possible factors contributing to these differences we measured light, plant densities and young leaf densities, as indicators of abiotic factors and food resources for insect herbivores. Arthropod abundance was negatively correlated with light in the dry season. Thus, abiotic stress may explain the pattern of abundance in the dry season. While there was no correlation with light in the rainy season, predator abundance was positively correlated with herbivore abundance. The plant and young leaf density data suggest that there is significantly higher food availability for herbivores in gaps. Thus, less stressful abiotic conditions and more food resources may contribute to more herbivores followed by more predators in gaps during the rainy season.
Article
Full-text available
Bird community response to both landscape-scale and local (forest types) changes in forest cover was studied in three boreal mixed-wood forest landscapes modified by different types of disturbances: (1) a pre-industrial landscape where human settlement, agriculture, and logging activities date back to the early 1930s, (2) an industrial timber managed forest, and (3) a forest dominated by natural disturbances. Birds were sampled at 459 sampling stations distributed among the three landscapes. Local habitat and landscape characteristics of the context surrounding each sampling station (500-m and 1-km radius) were also computed. Bird communities were influenced by landscape-scale changes in forest cover. The higher proportion of early-successional habitats in both human-disturbed landscapes resulted in significantly higher abundance of early- successional bird species and generalists. The mean number of mature forest bird species was significantly lower in the industrial and pre-industrial landscapes than in the natural landscape. Landscape-scale conversion of mature forests from mixed-wood to deciduous cover in human-disturbed landscapes was the main cause of changes in mature forest bird communities. In these landscapes, the abundance of species associated with mixed and coniferous forest cover was lower, whereas species that preferred a deciduous cover were more abundant. Variation in bird community composition determined by the landscape context was as important as local habitat conditions, suggesting that predictions on the regional impact of forest management on songbirds with models solely based on local scale factors could be misleading. Patterns of bird species composition were related to several landscape composition variables (proportions of forest types), but not to configuration variables (e.g., interior habitat, amount of edge). Overall, our results indicated that the large-scale conversion of the southern portion of the boreal forest from a mined to a deciduous cover may be one of the most important threats to the integrity of bird communities in these forest mosaics. Negative effects of changes in bird communities could be attenuated if current forestry practices are modified toward maintaining forest types (deciduous, mixed-wood, and coniferous) at levels similar to those observed under natural disturbances.
Article
Full-text available
The responses of hornbills to selective logging were determined by comparing their diversity abundance in five habitats classified according to logging history. Relative abundance of three hornbill species was compared along trails in recently logged forest 20–25-year-old logged forest unlogged primary forest a relatively disturbed primary forest a plantation in Pakhui Wildlife Sanctuary adjoining reserve forests in western Arunachal Pradesh. The species recorded were the Oriental pied hornbill Anthracoceros albirostris wreathed hornbill Aceros undulatus great hornbill Buceros bicornis. The great hornbill was the most common species overall its abundance varied across habitats being highest in unlogged forest. The Oriental pied hornbill which was recorded in only two habitats seemed to show a distinct habitat preference for secondary growth river-margin forests. Wreathed hornbill abundance did not differ between habitats. Differences in species abundance probably reflect aspects of their ecology such as degree of territoriality diet movement patterns differential vulnerability to hunting disturbance. Great hornbill abundance was correlated with large tree density (GBH &;ge 150 cm) basal area characteristic of unlogged primary forests while Oriental pied hornbill abundance was negatively correlated with tall forest indicating its greater numbers in low-stature river-margin forest. Wreathed hornbill abundance was not correlated with any vegetation variable which is probably related to its reported nomadic movements in search of fruit patches. Hornbill abundance was not correlated with densities of potential food nest tree species. Although hornbill abundance was not correlated with fig tree density this was probably because areas where relative fig tree densities were lower often contained a few large fruiting figs. Because hornbills are large mobile birds they can find resources such as fruiting figs even in otherwise unsuitable habitat.
Article
Full-text available
Although forest wildfires threaten to impoverish vast expanses of once fire-resistant humid tropical forest, their effects on the vertebrate fauna remain poorly under-stood. We report results from a study in central Brazilian Amazonia examining a large area of terra firma (unflooded) forest that had been affected by fires during the 1997–1998 El Niñ o-mediated dry season. By sampling 0.25-ha forest plots both one and three years after fire disturbance, we noted that over time the bird community became increasingly dissimilar from that in unburned control plots. The influences of burn severity and recurrent fires were then examined across 28 plots that were all sampled three years after the fires. Foraging guilds differed in their responses to the gradient of increasing burn severity; most guilds declined, although arboreal granivores, frugivores, and nectarivores showed unimodal re-sponses and arboreal gleaning insectivores increased. These responses were strongly cor-related with associated changes in the habitat structure and reflected differences in resource abundance where this was quantified. Rates of species turnover were high, and there was virtually no species overlap between unburned forest plots and those that had burned in more than one El Niñ o dry season. Our results indicate that, unless conservation strategies can prevent a recurrent fire regime from becoming established in seasonally dry tropical forests, only nonforest and second-growth bird species, which are of minimal conservation importance, will be able to persist in fire-prone landscapes of the future.
Article
Full-text available
1. Recovery of rainforest bird community structure and composition, in relation to forest succession after slash-and-burn shifting cultivation or jhum, was studied in Mizoram, north-east India. Replicate fallow sites abandoned after shifting cultivation 1, 5, 10, 25 and ≈100 years ago, were compared with primary evergreen and semi-evergreen forest using transect and quadrat sampling. 2. Vegetation variables such as woody plant species richness, tree density and vertical stratification increased with fallow age in a rapid, non-linear, asymptotic manner. Principal components analysis of vegetation variables summarized 92·8% of the variation into two axes: PC1 reflecting forest development and woody plant succession (variables such as tree density, woody plant species richness), and PC2 depicting bamboo density, which increased from 1 to 25 years and declined thereafter. 3. Bird species richness, abundance and diversity, increased rapidly and asymptotically during succession paralleling vegetation recovery as shown by positive correlations with fallow age and PC1 scores of sites. Bamboo density reflected by PC2 had a negative effect on bird species richness and abundance. 4. The bird community similarity (Morisita index) of sites with primary forest also increased asymptotically with fallow age indicating sequential species turnover during succession. Bird community similarity of sites with primary forest (or between sites) was positively correlated with both physiognomic and floristic similarities with primary forest (or between sites). 5. The number of bird species in guilds associated with forest development and woody plants (canopy insectivores, frugivores, bark feeders) was correlated with PC1 scores of the sites. Species in other guilds (e. g. granivores, understorey insectivores) appeared to dominate during early and mid-succession. 6. The non-linear relationships imply that fallow periods less than a threshold of 25 years for birds, and about 50–75 years for woody plants, are likely to cause substantial community alteration. 7. As 5–10-year rotation periods or jhum cycles prevail in many parts of north-east India, there is a need to protect and conserve tracts of late-successional and primary forest.
Article
Full-text available
A comprehensive understanding of variables associated with spatial differences in community composition is essential to explain and predict biodiversity over landscape scales. In this study, spatial patterns of bird diversity in Central Kalimantan, Indonesia, were examined and associated with local-scale (habitat structure and heterogeneity) and landscape-scale (logging, slope position and elevation) environmental variables. Within the study area (c. 196km2) local habitat structure and heterogeneity varied considerably, largely due to logging. In total 9747 individuals of 177 bird species were recorded. Akaike's information criterion (AIC) revealed that the best explanatory models of bird community similarity and species richness included both local- and landscape-scale environmental variables. Important local-scale variables included liana abundance, fern cover, sapling density, tree density, dead wood abundance and tree architecture, while important landscape-scale variables were elevation, logging and slope position. Geographic distance between sampling sites was not significantly associated with spatial variation in either species richness or similarity. These results indicate that deterministic environmental processes, as opposed to dispersal-driven stochastic processes, primarily structure bird assemblages within the spatial scale of this study and confirm that highly variable local habitat measures can be effective means of predicting landscape-scale community patterns.
Article
Full-text available
The composition and structure of bird communities, and the damage to forest structure were surveyed in northern French Guiana (northeastern Amazonia) one year and ten years after selective logging and compared with the situation in a similar undisturbed primary forest. A point-count method was used in which 937 0.25ha sample plots were censused for 20 minutes each, and their vegetation structure was measured. On average, 38% of the forest undergrowth was destroyed, then invaded by dense regrowth, and up to 63% of the canopy was substantially opened as a result of selective logging. Hunting pressure also increased due to access roads opened for logging. Among the 256 species recorded, overall bird species richness and abundance were depressed by 27–34% in the logged areas compared to primary forest. The most vulnerable guilds, which decreased by 37–98% in abundance, were mature forest understorey species, especially terrestrial ones and mixed flocks of insectivores. Hummingbirds, small gaps, vine tangles and canopy species did not decrease, nor increase significantly after logging. Only species naturally associated with dense second growth, forest edges and large gaps actually increased. Habitat specialization was the major determinant of vulnerability to logging, and, to a lesser degree, size (large) and diet (insectivorous), but foraging behaviour and rarity had little effect. Bird sensitivity to changes in logged forest structure may involve physiological intolerance, reduced food categories, increased exposure to predators, too dense understorey for their specific foraging behaviour and/or avoidance of gaps. Suggested improvements of current forest management and logging techniques for the maintenance of a higher proportion of the original biodiversity include minimizing logging damages, long rotations (>50 years) between cuts, and keeping unlogged forest patches within logging concessions.
Article
Full-text available
Oak (Quercus spp.) forests represent the climax evergreen vegetation between 1000–3600 m in the Central Himalaya. Shrub layer is well developed in these forests and phanerophytes prevail (50–60%). Though one oak species mixes frequently with other oak species, or conifers, the single-species dominance is quite common. All the oak forests are vulnerable to fire. They support a great variety of wildlife. Coppicing subsequent to cutting is well developed in all oak species and helps them in regeneration. However, because of severe biotic stress oaks are failing to regenerate in forest stands. The forest biomass ranges between 294–787 t ha−1 and the net primary productivity generally between 16–21 t ha−1 yr−1. Oak forests store a large proportion of their nutrients in biomass component. Leaves are nutrient-rich and decompose rapidly. Evergreen woody species with concentrated summer leaf drop prevail in oak forests. The seasonality of the ecosystem activities seem to be influenced by the monsoon pattern of rainfall. Though the recovery is rapid after the forest destruction, because of continuous and severe biotic stress, oaks are being replaced with other communities.
Article
An increasing proportion of ecological studies examine landscape effects on the phenomena they address. We reviewed studies which simultaneously considered landscape-scale and patch-scale effects in order to answer the following question: does the inclusion of landscape characteristics as explanatory variables increase our ability to predict species presence and abundance when local (i.e., habitat patch) conditions are known? The 61 studies selected cover a wide array of taxa, landscape types, and explanatory variables, but many (36%) focused on avian communities in forests fragmented by agriculture. Patch-scale variables (e.g., habitat characteristics) had a significant effect on invertebrates, amphibians, reptiles, birds, and mammals in all landscape types. Landscape-scale characteristics (e.g., area of suitable habitat within a certain radius of a patch) also were significant predictors of species presence and abundance for vertebrates, but not for the majority of invertebrates in the studies we reviewed. Thus, our results indicate that both patch and landscape characteristics should be included in models investigating the distribution and abundance of animals, at least for vertebrates. However, distinguishing between local (or patch) and landscape scales for particular taxa is often problematic. Analyzing movements of individuals and their influence on larger-scale population dynamics could potentially solve this dilemma, but other approaches, such as the analysis of context effects using nested sampling grids covering several different spatial scales may represent a more practical alternative. Results from this review suggest that the inclusion of landscape characteristics will enhance conservation strategies if the landscape scale is properly defined with respect to the taxon or taxa under investigation.
Article
In the Kroumirie ecoregion of northwestern Tunisia, habitat fragmentation and degradation are the main drivers of contemporary landscape change. Continuous native oak forests have been converted into heterogeneous landscapes characterized by small forest fragments surrounded by a scrubby matrix. We examined the response of five species of cavity-nesting birds to these phenomena because they play a keystone role in these forest ecosystems. We quantified the relative effects of landscape composition and the configuration of mature oak forest on the occurrence of the focal species. We hypothesized that the occurrence of all focal species would increase with forest cover, whereas the effects of matrix type and mature forest configuration would be species-specific. For each focal species, we tested a set of 12 candidate models predicting their occurrence. Each model included landscape metrics describing oak forest configuration and landscape composition. We applied multimodel inference and model averaging on generalized linear models. Forest cover at the landscape level was the main driver of species occurrence. Secondary cavity-nesters responded positively to the proportion of oak forest at landscape and local scales, whereas the five focal species responded negatively to the proportion of low scrub. Great spotted woodpecker (Dendrocopos major) and Levaillant’s woodpecker (Picus vaillantii) responded positively to both forest amount and high scrub, suggesting a landscape complementation process. Lesser spotted woodpecker (D. minor) was the only species responding to forest configuration, possibly as a result of landscape supplementation. High scrub appeared to moderate the contrast between low scrub and forest fragments for primary cavity-nesters. However, it did not influence the occurrence of secondary cavity-nesters (e.g., Atlas flycatcher Ficedula speculgera and short-toed treecreeper Certhia brachydactyla). If an increase in the amount of mature oak forest cannot be achieved over the short term, the maintenance of high scrub around forest fragments and an improvement in the quality of low scrub through the addition of vertical structure should increase the frequency of occurrence of many of our focal species in oak forest of the Mediterranean Basin.
Article
en The impacts of land‐use change on biodiversity in the Himalayas are poorly known, notwithstanding widespread deforestation and agricultural intensification in this highly biodiverse region. Although intact primary forests harbor many Himalayan birds during breeding, a large number of bird species use agricultural lands during winter. We assessed how Himalayan bird species richness, abundance, and composition during winter are affected by forest loss stemming from agriculture and grazing. Bird surveys along 12 elevational transects within primary forest, low‐intensity agriculture, mixed subsistence agriculture, and intensively grazed pastures in winter revealed that bird species richness and abundance were greatest in low‐intensity and mixed agriculture, intermediate in grazed pastures, and lowest in primary forest at both local and landscape scales; over twice as many species and individuals were recorded in low‐intensity agriculture than in primary forest. Bird communities in primary forests were distinct from those in all other land‐use classes, but only 4 species were unique to primary forests. Low‐, medium‐, and high‐intensity agriculture harbored 32 unique species. Of the species observed in primary forest, 80% had equal or greater abundance in low‐intensity agricultural lands, underscoring the value of these lands in retaining diverse community assemblages at high densities in winter. Among disturbed landscapes, bird species richness and abundance declined as land‐use intensity increased, especially in high‐intensity pastures. Our results suggest that agricultural landscapes are important for most Himalayan bird species in winter. But agricultural intensification—especially increased grazing—will likely result in biodiversity losses. Given that forest reserves alone may inadequately conserve Himalayan birds in winter, comprehensive conservation strategies in the region must go beyond protecting intact primary forests and ensure that low‐intensity agricultural lands are not extensively converted to high‐intensity pastures. Abstract es La Importancia de las Tierras Agrícolas para las Aves del Himalaya en el Invierno Resumen Los impactos del cambio de uso de suelo sobre la biodiversidad en el Himalaya son poco conocidos, a pesar de la deforestación extendida y la intensificación agrícola en esta región altamente biodiversa. Aunque los bosques primarios intactos albergan a muchas aves del Himalaya durante la época reproductiva, un gran número de especies de aves utilizan las tierras agrícolas durante el invierno. Valoramos cómo la riqueza, abundancia y composición de especies de aves del Himalaya durante el invierno son afectadas por la pérdida del bosque a partir de la agricultura y el pastoreo. Los censos de aves a lo largo de doce transectos de altitud dentro del bosque primario, de la agricultura de baja intensidad, de la agricultura de subsistencia mixta y de las zonas de pastoreo intensivo en invierno revelaron que la riqueza de especies de aves y la abundancia fueron mayores en la agricultura de baja intensidad y en la mixta, intermedias en las zonas de pastoreo, y más bajas en el bosque primario tanto en la escala local como la de paisaje; más del doble de especies y de individuos se registraron en la agricultura de baja intensidad que en el bosque primario. Las comunidades de aves en el bosque primario fueron distintas de aquellas en todos los demás tipos de uso de suelo, pero sólo cuatro especies fueron únicas de los bosques primarios. La agricultura de intensidad baja, media y alta albergó 32 especies únicas. De las especies observadas en el bosque primario, el 80 % tuvo una abundancia igual o mayor en los suelos de baja intensidad agrícola, enfatizando el valor de estos suelos en la retención de ensamblajes diversos de comunidades a densidades altas durante el invierno. Entre los paisajes perturbados, la riqueza de especies y la abundancia declinaron conforme incrementó la intensidad del uso de suelo, especialmente en las pasturas de alta intensidad. Nuestros resultados sugieren que los paisajes agrícolas son importantes para la mayoría de las especies de aves del Himalaya durante el inverno; aunque la intensificación agrícola – especialmente el pastoreo incrementado – probablemente resultará en la pérdida de la biodiversidad. Dado que las reservas de bosques por sí solas pueden conservar inadecuadamente a las aves del Himalaya en inverno, las estrategias integrales de conservación en la región deben ir más allá de proteger los bosques primarios intactos y asegurar que los suelos de uso agrícola de baja intensidad no sean convertidos extensivamente a zonas de pastoreo de alta intensidad.
Code
Tools for performing model selection and model averaging. Automated model selection through subsetting the maximum model, with optional constraints for model inclusion. Model parameter and prediction averaging based on model weights derived from information criteria (AICc and alike) or custom model weighting schemes. [Please do not request the full text - it is an R package. The up-to-date manual is available from CRAN].
Article
India has rich traditions of nature conservation as well as a vigorous official program of protection of nature reserves developed over the last 40 years. However, the official program suffers from total reliance on authoritarian management arrangements in which decisions are made centrally and coercion is used to implement them. At the same time, the state apparatus organises subsidized resource flows to the urban-industrial intensive agricultural complex which promote inefficient, non-sustainable resource-use patterns that are inimical to conservation of biodiversity. These processes are illustrated within the concrete setting of the district of Uttara Kannada in southern India. The paper goes on to illustrate an alternative approach, and to suggest how it could be implemented. -from Author
Article
Effects of various intensities of lopping on the growth of trees, production and grass biomass production were investigated in the Western Ghats, India. Frequent complete lopping resulted in a reduction in growth of tree girth and production of leafy biomass. Relatively greater increase in girth was observed in trees subjected to partial lopping. Opening of canopy increased the grass production in lopped quadrats. In two species, Aporosa lindleyana and Terminalia paniculata, the growth rate of girth and the yearly production of leafy biomass showed positive correlation up to 75% lopping intensity indicating that these two species can withstand lopping to some extent. -from Authors
Article
This study examines the practice of lopping of Quercus leucotrichophora A. Camus and Quercus floribunda Lindley ex Rehder in Garhwal Himalaya. The study objectives were to investigate the lopping process, the factors that influence it, and the changes it has undergone between 1993 and 2006, specifically, age and gender roles, method of fodder collection, type of branches and trees lopped, and weight of oak foliage bundles. Data were collected for 49 fodder collection trips in Beli village, Tehri Garhwal District, Garhwal Division. Four closely interlinked factors influenced forest use—gender roles, availability of oak foliage in the forest, number and type of livestock per household, and type of agricultural crops planted. The results indicate that lopping practice is not static. It has undergone fundamental changes between 1993 and 2006. Beli villagers continued to collect fodder basis, varied the fodder species collected, and rotated the location of trees lopped throughout the year in 2006, as they did in 1993. Foliage collection intensified until early 2000 when there was a marked decrease in the amount of foliage available in the forest. As a result, the villagers began to reduce their total reliance on the forest and agriculture for income and instead began to send their children to school in preparation for employment outside the village. This change in livelihood strategy is reflected in the lopping practice. Fodder collection trips decreased from 5 in 1993 to 3 times a day in 2006. The number of people collecting Q. floribunda decreased from 26 to 12, with fodder being collected mainly by women aged 21 to 26. This has resulted in females carrying significantly greater loads in 2006 (P = 0.0004). Examining the lopping practice provides insights into the impact of fodder collection on forest ecosystems and, in turn, the forest's impact on peoples' lives.
Article
Thematic mapping via a classification analysis is one of the most common applications of remote sensing. The accuracy of image classifications is, however, often viewed negatively. Here, it is suggested that the approach to the evaluation of image classification accuracy typically adopted in remote sensing may often be unfair, commonly being rather harsh and misleading. It is stressed that the widely used target accuracy of 85% can be inappropriate and that the approach to accuracy assessment adopted commonly in remote sensing is pessimistically biased. Moreover, the maps produced by other communities, which are often used unquestioningly, may have a low accuracy if evaluated from the standard perspective adopted in remote sensing. A greater awareness of the problems encountered in accuracy assessment may help ensure that perceptions of classification accuracy are realistic and reduce unfair criticism of thematic maps derived from remote sensing.
Article
In 2004, Navjot Sodhi and colleagues warned that logging and agricultural conversion of Southeast Asia's forests were leading to a biodiversity disaster. We evaluate this prediction against subsequent research and conclude that most of the fauna of the region can persist in logged forests. Conversely, conversion of primary or logged forests to plantation crops, such as oil palm, causes tremendous biodiversity loss. This loss is exacerbated by increased fire frequency. Therefore, we conclude that preventing agricultural conversion of logged forests is essential to conserving the biodiversity of this region. Our analysis also suggests that, because Southeast Asian forests are tightly tied to global commodity markets, conservation payments commensurate with combined returns from logging and subsequent agricultural production may be required to secure long-term forest protection.
Article
Among boreal forest bird species, the three-toed woodpecker (Picoides tridactylus) is closely associated with old-growth forests (>120 years), and possibly the most negatively affected by long-term changes induced by commercial forestry in eastern Canada. Part of this conflict is related to the woodpecker's use of standing dead trees as nesting sites. Moreover, this woodpecker's foraging behavior and its choice of feeding and drumming substrates may increase its vulnerability in managed forests. We describe foraging behavior of three-toed woodpeckers, and characterize foraging and drumming trees used by this species in Quebec's black spruce (Picea mariana) forests. During summer (May-Jul) and mid-winter (Jan-Feb), birds of both sexes used a highly specialized feeding technique consistent with searching for bark beetles (Coleoptera: Scolytidae). Snags were highly preferred over live trees as foraging substrates. Snags used for foraging had a greater diameter at Breast height (dbh) and were less deteriorated than paired nearest available snags. When live trees were selected for foraging, they also had a greater dbh but were more deteriorated than nearest available live trees. Thus, only a limited number of trees had all characteristics preferred by foraging woodpeckers, probably as a result of the ecology of its phloem-boring prey. Snags also were highly preferred over live trees as drumming substrates. Drumming snags differed from paired nearest available snags by having a broken top, less bark cover, and a lower deterioration class, which probably provided better acoustic towers for territorial birds. Given the extensive use of snags with different characteristics for foraging and drumming by three-toed woodpeckers, models estimating snag requirements for this species based only on nesting requirements are probably of limited use to maintain populations in managed areas. Wildlife habitat management objectives that specifically require the maintenance and renewal of snags in early decaying stages found in old-growth forests are essential to the conservation of this woodpecker species in managed forests. [References: 45]
Article
The use of both linear and generalized linear mixed‐effects models ( LMM s and GLMM s) has become popular not only in social and medical sciences, but also in biological sciences, especially in the field of ecology and evolution. Information criteria, such as Akaike Information Criterion ( AIC ), are usually presented as model comparison tools for mixed‐effects models. The presentation of ‘variance explained’ ( R ² ) as a relevant summarizing statistic of mixed‐effects models, however, is rare, even though R ² is routinely reported for linear models ( LM s) and also generalized linear models ( GLM s). R ² has the extremely useful property of providing an absolute value for the goodness‐of‐fit of a model, which cannot be given by the information criteria. As a summary statistic that describes the amount of variance explained, R ² can also be a quantity of biological interest. One reason for the under‐appreciation of R ² for mixed‐effects models lies in the fact that R ² can be defined in a number of ways. Furthermore, most definitions of R ² for mixed‐effects have theoretical problems (e.g. decreased or negative R ² values in larger models) and/or their use is hindered by practical difficulties (e.g. implementation). Here, we make a case for the importance of reporting R ² for mixed‐effects models. We first provide the common definitions of R ² for LM s and GLM s and discuss the key problems associated with calculating R ² for mixed‐effects models. We then recommend a general and simple method for calculating two types of R ² (marginal and conditional R ² ) for both LMM s and GLMM s, which are less susceptible to common problems. This method is illustrated by examples and can be widely employed by researchers in any fields of research, regardless of software packages used for fitting mixed‐effects models. The proposed method has the potential to facilitate the presentation of R ² for a wide range of circumstances.
Article
We investigated howmuch forest structure and floristics independently contributed to the composition of avian assemblages at multiple scales and for individual foraging guilds in tropical deciduous forests of Central Highlands, India. We derived dissimilarity matrices between all pairs of the 36 sampling sites with respect to forest structure, floristics, and bird species composition and ran Mantel’s randomization tests to detect significant associations among the matrices after partialling out the effect of geographic distance between sites. Bird species composition was found to be significantly related to forest structure across habitats, and floristics within the moist-deciduous forests. This finding is consistent with earlier observations that birds respond, in their species composition, to vegetation structure across habitats and to vegetation composition within a habitat. As predicted, the composition of insectivorous birds was influenced by forest structure, but the phytophagous guild did not show any relation to vegetation composition in contrast to patterns observed elsewhere. We explain this anomaly as a result of availability of a wide choice of food plants for phytophagous birds in central Indian tropical forests and weak species–environment relationships on account of their nomadism. Extraction of non-timber forest products remains a key economic activity in central India and our results imply that it can potentially influence the composition of forest bird communities through alteration of forest structure and floristics.
Article
Semi-natural cork oak woodlands are a biodiversity rich agro-silvo-pastoral system covering large areas in the Mediterranean. Canopies of adult oaks are often pruned, but nothing is known about the consequences of this treatment on biodiversity. We evaluated the impact of pruning on birds that forage in cork oak canopies in an area of southern Portugal. We characterized the use of trees by foraging birds with focal observations, and analysed the effects of pruning on density with point counts on pruned and control areas. As pruning reduces the foraging substrate for foliage gleaners, we predicted that these species would have lower densities in pruned areas. Pruning did not substantially affect overall bird density or species richness. However, as predicted, the density of species that foraged mostly by gleaning in the canopy tended to be lower in pruned areas, especially in winter when differences were statistically significant. In this season the combined density of foliage gleaners in the pruned stations was only half of that in controls. Pruning is also common in other managed Mediterranean woodlands that are important for birds, such as holm oak woodlands and olive groves, and foliage gleaners are likely to be affected in those too. The cumulative effects of pruning on all these habitats need to be assessed, but our results already indicate that pruning has negative consequences that should be properly considered in management decisions.
Article
This paper describes changes in bird communities following the conversion of lowland forest to commercial oil palm and rubber plantations. Conversion of forest to plantations resulted in a reduction in species richness of at least 60%, with insectivores and frugivores suffering greater losses than more omnivorous species. Of the 128 species recorded across all habitats, 84% were recorded in forest, and 60% were recorded only in that habitat. Of the 16 Globally Threatened or Near-Threatened species recorded in the study, 15 were recorded only in forest. Species occurring in plantations were significantly more widespread in Thailand than species recorded only in forests and had a tendency towards smaller body size. Species richness in plantations was unaffected by plantation age or distance from nearest forest edge, but was significantly greater where undergrowth was allowed to regenerate beneath the crop trees. Bird communities in oil palm and rubber plantations were extremely similar, and there was a strong positive correlation across species in their relative abundance in each plantation type. The results indicate that a high proportion of species formerly present in the region are unable to adapt to conversion of forest to oil palm and rubber plantations, resulting in large losses of bird species and family richness and the replacement of species with restricted ranges and high conservation status by those with extensive ranges and low conservation status. Initiatives that reduce pressure to clear new land for plantations, for example by increasing productivity in existing plantations and improving protected area networks, are likely to be more effective in conserving threatened forest birds than initiatives to improve conditions within plantations, though both should be encouraged.
Article
A study was carried out in a tropical scrub forest in India, to investigate the effects of extractive activities such as fodder and firewood collection, on native bird communities and to study the relative influences of altered vegetation composition and structure. The study was based on comparison between six ‘disturbed’ (extracted) and four ‘undisturbed’ (non-extracted) sites that were delineated using quantitative disturbance indicators. Birds were sampled seven times over two different seasons utilising the fixed radius point count method. Six different variables related to vegetation structure (canopy cover, basal area, average forest height, tree density, tree height diversity and tree species richness) were quantified, as was tree species composition. There was no significant difference in number of recorded species or bird abundance between disturbed and undisturbed sites. However, bird species diversity was significantly lower in disturbed sites in comparison to undisturbed sites. Overall, bird species composition also differed significantly between disturbed and undisturbed sites. Nine of 38 locally abundant bird species (23.6%) showed significant selection for either disturbed or undisturbed habitats. Of these nine species, seven chose undisturbed habitats and two chose disturbed. All seven species adversely affected by disturbance are primarily insectivorous. Canopy cover, tree basal area and height of trees were significantly lower in disturbed sites in comparison to undisturbed sites. In both habitats, bird species composition was significantly dependent on these components of altered vegetation structure. Tree species composition was also significantly altered by disturbance in scrub forest. However, altered tree species composition did not significantly affect bird species composition. Partial Mantel's tests confirmed that there were no significant residual effects of tree species composition on bird composition after the effects of vegetation structure were accounted for. Our study indicates that rural biomass extraction can have significant effects upon bird species composition of tropical scrub forest which is caused principally by alteration of vegetation structure, rather than by changes in forest tree composition.
Article
Although the Guinea–Congolian rain forest region is an important focal point for conservation in Africa, very little information is available on the effects of forest modification and land use on the region's biodiversity. We studied bird communities and vegetation characteristics in 24 sampling stations distributed over two near-natural forests (near-primary forest, secondary forest), and two land use types (agroforestry, annual cul-tures) in the lowlands of the Korup region, Cameroon. Repeated sampling was used to establish near-complete inventories of bird assemblages for each site. Despite a 90% average drop in tree basal area from forest to farmland, overall bird species richness did not decrease significantly with increasing habitat modification. However, different groups of birds re-sponded in different ways. Frugivorous and omnivorous bird species richness did not differ between habitats, whereas richness in granivorous, flower-visiting, and nonbreeding species was higher in land use systems compared to forests. In contrast, insectivorous birds, es-pecially terrestrial and large arboreal foliage gleaning insectivores, and ant followers showed a declining species richness from forest to farmland. Also, richness in species of those restricted to the Guinea–Congolian forest biome and of the family Pycnonotidae showed a pronounced decline with increasing habitat modification. Species richness of overall insectivores, terrestrial insectivores, large-and medium-sized arboreal foliage gleaners, ant followers, as well as pycnonotids and biome-restricted species, were strongly or even very strongly positively correlated with overstory tree density and, in most cases, also with basal area. In contrast, tree density and basal area were strongly negatively correlated with species richness of nonbreeding visitors and flower-visiting bird species. Species composition was most distinct between near-primary forest and annual culture sites, and the abundance of 23 out of 165 species was affected by habitat, suggesting considerable partitioning of habitat niches along the habitat gradient. Our results stress the importance of tree cover in tropical land use systems for the maintenance of resident forest bird populations and confirm that natural forest management is more beneficial for global bird conservation compared to other forms of forest exploitation, including agroforestry systems.
Article
1. There is an urgent need to understand the impacts of anthropogenic habitat disturbance on biodiversity in tropical forests, but no consensus has yet emerged. We reviewed the literature for the most frequently studied taxon (birds, 37 studies) and found that increased and decreased diversity in response to disturbance (selective logging and shifting agriculture) were reported with approximately equal frequency. 2. The spatial scale at which studies were carried out significantly affected the reported response to disturbance: studies where disturbed and undisturbed habitats were sampled at large spatial scales were more likely to report increased diversity following disturbance, whereas studies that sampled habitats at small spatial scales were more likely to report decreased diversity. These results were not a consequence of sampling method: we divided the studies into those using capture methods and those using observation methods and the same result was obtained when the analysis was restricted to only those studies using observation methods. 3. Previously, we have shown that reported impacts of disturbance on Lepidoptera are also affected by the spatial scale of study. We reviewed the Lepidoptera literature published since then and showed that all 12 new studies conformed to the predicted pattern. 4. While sampling scale significantly affected the reported responses of both birds and Lepidoptera, there were opposite effects of scale in the two taxa: large-scale bird studies and small-scale Lepidoptera studies were more likely to report increased diversity following disturbance. Bird studies were generally carried out at larger spatial scales than those of Lepidoptera and these opposite impacts of scale were probably due to a non-linear effect of habitat disturbance on habitat heterogeneity at different spatial scales. 5. Synthesis and applications. The rapid loss and degradation of tropical forests means that an understanding of the general patterns of responses of species to habitat disturbance is urgently needed. However, there has been little discussion of the most appropriate methods to ensure comparability of results between studies. Data presented here indicate that the spatial scale of sampling chosen in studies has a marked effect on the results obtained, and future studies need to account for this by examining explicitly the effects of disturbance at different spatial scales. The effect of spatial scale differs between taxa, and this may explain why the search for indicator taxa of disturbance effects has so far proved elusive.
Article
1Tests of habitat association among species of tropical trees and shrubs often assume that individual stems can be treated as independent sample units, even though limited dispersal conflicts with this assumption by causing new recruits to occur near maternal parents and siblings.2We developed methods for assessing patterns of association between mapped plants and mapped habitat types that explicitly incorporate spatial structure, thereby eliminating the need to assume independence among stems.3We used these methods to determine habitat-association patterns for 171 species of trees and shrubs within the permanent 50-ha Forest Dynamics Project plot on Barro Colorado Island, Panama.4Many fewer significant habitat associations result from the new methods than from traditional, but inappropriate, chi-square tests. The low-lying plateau, the most extensive habitat on the 50-ha plot, had nine species positively associated with it and 19 species negatively associated, leaving 143 species whose distributions were not biased with respect to this habitat. A small swamp in the plot was the most distinct habitat, with 32 species positively and 20 species negatively associated, leaving more than two-thirds of the species neither positively nor negatively associated.5To the extent that habitat association reflects habitat specialization, our results suggest that local habitat specialization plays a limited role in the maintenance of species diversity in this forest.
Article
The composition and structure of the bird community were investigated in French Guiana (northeastern Amazonia) 1 year and 10 years after selective logging and compared with bird community composition and structure in undisturbed primary forest. A point-count method was used in which 937 0.25-ha sample quadrats were censused for 20 minutes each. Whereas logging removed little more than 3 trees/ha, 38% of the forest undergrowth was destroyed and a proportion of the canopy was opened or damaged. An overall 27–33% decrease of species richness, frequency, and abundance occurred after logging, with a less marked decline of diversity and evenness indices, a substantial increase in the proportion of dominant species, and a 45% difference in species composition, weighed by frequency, between logged and undisturbed forest communities. Forty-two percent of the species from the primary forest decreased sharply or disappeared after logging and only 34% increased or remained unchanged. Microhabitat selection was the main correlate of sensitivity to disturbance. Most affected by logging were species associated with the understory of tall mature stands especially terrestrial species, members of mixed flocks, and solitary sallying insectivores, all of which decreased by 70% to over 90%. Most birds associated with canopy, small gaps, and vine tangles declined by only 10–30%. Small frugivores and species associated with clearings or edges increased. Among other factors, physiological intolerance of understory species to open forest microclimatic conditions (light, heat, or water stress) might influence their avoidance of logged areas. Timber harvesting generated a high level of disturbance, which depressed the bird diversity. After over 10 years of regeneration, the dense regrowth produced a uniform habitat type that still had not recovered the high species richness exhibited by the primary forest under an intermediate level of disturbance.
Article
1 Relationships between microhabitat variables (altitude, inclination, topographic position, drainage, canopy height) and the distribution and abundance of palms and palm-like plants in 50 ha of old-growth terra firme rain forest in the Yasuní National Park, lowland Amazonian Ecuador, were examined using 118 20 × 20 m plots laid out in a stratified random design. 2 If microhabitat niche differentiation is important for maintaining the species richness of the community, then (i) the distribution of the palms will be strongly influenced by microhabitat heterogeneity and (ii) palms of similar growth form will show antagonistic microhabitat relationships. 3 Mantel and cluster analyses showed that palm species distributions were strongly structured by topography. The main difference in species composition was between plots in the bottomland and plots on the upper slopes and hill tops. 4 Logistic and logit analyses showed that 20 of the 31 palm and palm-like taxa analysed had distributions that were significantly related to the microhabitat variables measured, mainly to topography but also to drainage and canopy height. 5 Spatial autocorrelation in the overall community structure was not explained by the microhabitat variables. Analyses of distributions or abundances of single species showed neighbourhood effects for seven taxa. 6 Antagonistic patterns of microhabitat preferences were recognizable among some species pairs of small palms, medium-sized palms and palm-like plants, but not among canopy palms. 7 It is concluded that microhabitat specialization is an important factor in maintaining the diversity of this palm community, while mass effects might also be important.
Article
In recent years, studies of bird-habitat relationships undertaken in the context of habitat fragmentation have led to the widespread use of species categorisation according to their response to edge alongside mature forest patches (edge species, interior species, interior-edge generalist species). In other research contexts, especially in less fragmented landscapes dominated by a forested land base in various age classes, bird-habitat relationships are often described in relation to their use of various successional stages (early-successional species, mature forest species, generalist species). A simple comparison of these two commonly-used classifications schemes in a close geographical range for 60 species in eastern North America as well as for 36 species in north-western Europe clearly reveals that in these two particular biomes the two classifications are not independent. We believe that this association is not only a semantic issue and has important ecological consequences. For example, almost all edge species are associated with early-successional habitats when a wide range of forest age-classes are found in a given area. Accordingly, we suggest that most species considered to prefer edge habitats in agricultural landscapes are in fact only early-successional species that could not find shrubland conditions apart from the exposed edges of mature forest fragments. To be considered a true edge species, a given species should require the simultaneous availability of more than one habitat type and consequently should be classified as a habitat generalist in its use of successional stages. However, 28 out of 30 recognised edge species were considered habitat specialists in terms of successional status. Based on these results, we conclude that “real edge species” are probably quite rare and that we should make a difference between true edge species and species which in some landscapes, happen to find their habitat requirements on edges.