1,721,023 research outputs found
Loss of remnant trees causes local population collapse of endemic Grosbeak Starling Scissirostrum dubium in Central Sulawesi, Indonesia
No full textLarge and isolated trees are often last refuges for rare forest species in highly fragmented and human-dominated landscapes. This is of particular importance in tropical forest margin areas where remnant forest trees are being cleared at an alarming rate. Drivers and consequences of such remnant forest tree losses are still poorly documented. Here we report the rapid destruction of remnant trees, closely associated with colonies of the Sulawesi endemic Grosbeak Starling Scissirostrum dubium, which excavates nest holes in large dead trees. In 2008, we mapped all the species's potential breeding trees, tree characteristics and the local population density on the east margin of Lore Lindu National Park, Central Sulawesi, Indonesia. When the area was revisited in 2010, we found a dramatic loss of 92% of the recorded nest sites, accompanied by a remarkable decline of the local Grosbeak Starling population. This study provides an alarming example of the immediate consequences of the loss of remnant forest trees in tropical human-dominated landscapes for species dependent on this habitat structure. Without the contemporary implementation of strategies maintaining a high density of isolated large trees in forest margin zones and adjacent cultivated areas, associated species will experience dramatic population declines and a high local and, in the mid-to long-term, a high regional risk of extinction
Divergent farmer and scientist perceptions of agricultural biodiversity, ecosystem services and decision-making
Full text linkBiodiversity-friendly management is pivotal for sustainable agriculture, but rarely put into practice by farmers despite mounting evidence of the social, environmental, and economic benefits of such practices. We investigated the reasons for this implementation challenge by conducting a transdisciplinary survey to identify differences between perceptions of 208 farmers and 98 environmental scientists from Germany and Austria toward biodiversity, ecosystem services and the decision-making processes shaping agricultural landscapes. Perceptions of biodiversity, agri-environment schemes and conservation measures differed significantly between scientists and farmers. While scientists valued scientific information as more important for agricultural decision-making, farmers valued government and agricultural-sector information sources. We found more “biodiversity-positive” perceptions in female-, organic-, and more highly-educated-farmers, highlighting opportunities for more targeted promotion of conservation schemes. Survey respondents were generally younger than the population averages for both farmers and scientists, and our results therefore provide important insights for the future of biodiversity-friendly farming and related conservation science. Our findings demonstrate the urgent need for enhanced communication platforms and cooperation between scientists and key agricultural stakeholders to establish open dialogues between agricultural research, practice, and policy
How ants, birds and bats affect crop yield along shade gradients in tropical cacao agroforestry
No full textTropical agroforests are diverse systems where several predator groups shape animal communities and plant-arthropod interactions. Ants, birds and bats in particular can reduce herbivore numbers and thereby increase crop yield. However, the relative importance of these groups, whether they interact, and how this interaction is affected by management and landscape context, is poorly understood. We jointly manipulated access of ants, birds and bats in Indonesian smallholder cacao agroforestry across gradients of shade and distance to natural forest. We quantified arthropod abundance, pest damage and yield. In control treatments, yield was highest under 30-40% canopy cover. Ant exclusion strongly reduced yield (from 600 to 300 kg ha-1 year-1) at 15% canopy cover. Bird exclusion impaired yield (from 400 to 250 kg ha-1 year-1) at 60% and enhanced yield (from 600 to 900 kg ha-1 year-1) at 15% canopy cover, while bats had no effect. Yield increased with forest proximity, a pattern not related to predator access. No interactive effects among predator exclusions on yield, pest damage and arthropod communities were found. Ant exclusion increased numbers of herbivores below 30% canopy cover, without reducing spider abundances. Bird exclusion reduced herbivore and increased spider abundances. Synthesis and applications. Using exclusion studies, we estimated that ants and birds cause cacao yield to vary between 100 and 800 kg ha-1 year-1, depending on shade-tree management. In all but the most shaded agroforests, ants were pivotal in supporting yields. Yields under low-canopy cover were strongly dependent on access by predator groups, with birds reducing rather than increasing yield. Hence, cacao farmers should refrain from disturbing ant communities and maintain 30-40% shade-tree canopy cover not only for ecophysiological reasons but also to buffer variability in predator communities
Six years of habitat modification in a tropical rainforest margin of Indonesia do not affect bird diversity but endemic forest species
No full textStudies on temporal changes of tropical bird communities in response to habitat modification are rare. We quantified changes in bird assemblages at the rainforest margin of Lore Lindu National Park, Central Sulawesi, over an interval of 6 years. Standardized bird counts were conducted in the years 2001/2002 and 2008 at 15 census points representing natural forest, secondary forest, agroforest and openland sites. Although overall species richness remained nearly identical, different species groups were affected unequally by habitat modification within the forest margin landscape. The mostly endemic forest species declined in abundance (72.0% of forest species) and were detected at fewer census points in 2008 (56.0%). In contrast, 81.8% of the solely widespread openland birds became more abundant and 63.6% of the species were recorded at a larger number of census points. Hence, recent human activities in the forest margin ecotone negatively affected species of high conservation value. Species richness turned out to be a poor indicator of habitat change, and our results underline the importance of considering species identities. Biotic homogenization as result of habitat conversion is a global phenomenon. In our study, the winners were widespread openland species, while the losers were endemic forest birds. In conclusion, our study shows that 6 years of land-use change had negative impacts on bird community structure and endangered species, but not on overall bird species richness
Avian species identity drives predation success in tropical cacao agroforestry
No full textAvian ecosystem services such as the suppression of pests are considered to be of high ecological and economic importance in a range of ecosystems, especially in tropical agroforestry. However, how bird predation success is related to the diversity and composition of the bird community, as well as local and landscape factors, is poorly understood. We quantified arthropod predation in relation to the identity and diversity of insectivorous birds using experimental exposure of artificial, caterpillar-like prey in 15 smallholder cacao agroforestry systems differing in local shade-tree management and distance to primary forest. The bird community was assessed using both mist-netting (targeting active understorey insectivores) and point counts (higher completeness of species inventories). Bird predation was not related to local shade-tree management or overall bird species diversity, but to the activity of insectivorous bird species and the proximity to primary forest. Insectivore activity was best predicted by mist-netting-based data, not by point counts. We identified the abundant Indonesian endemic lemon-bellied white-eye Zosterops chloris as the main driver of predation on artificial prey.Synthesis and applications. The suppression of arthropods is a major ecosystem service provided by insectivorous birds in agricultural systems world-wide, potentially reducing herbivore damage on plants and increasing yields. Our results show that avian predation success can be driven by single and abundant insectivorous species, rather than by overall bird species richness. Forest proximity was important for enhancing the density of this key species, but did also promote bird species richness. Hence, our findings are both of economical as well as ecological interest because the conservation of nearby forest remnants will likely benefit human needs and biodiversity conservation alike. The suppression of arthropods is a major ecosystem service provided by insectivorous birds in agricultural systems world-wide, potentially reducing herbivore damage on plants and increasing yields. Our results show that avian predation success can be driven by single and abundant insectivorous species, rather than by overall bird species richness. Forest proximity was important for enhancing the density of this key species, but did also promote bird species richness. Hence, our findings are both of economical as well as ecological interest because the conservation of nearby forest remnants will likely benefit human needs and biodiversity conservation alike
Bats in the Anthropogenic Matrix: Challenges and Opportunities for the Conservation of Chiroptera and Their Ecosystem Services in Agricultural Landscapes
No full textSummary of research results, management recommendations and farmer workshops from cacao agroforestry landscapes in Indonesia
No full textSoftcover, 17,6x25Cacao agroforestry systems are common in Indonesia, but differences in local management affect
biodiversity and related ecosystem services. Importantly, birds and bats alike strongly contribute
to biological pest control in cacao, thereby promoting yields and sustainable farming. Our findings
from many years of ecological field research, in close collaboration with Indonesian cacao farmers,
are summarized and discussed in this bilingual book, written in both English and Indonesian. It is
designed to communicate scientific information as well as to facilitate transdisciplinary discussions
and more biodiversity-friendly management in tropical agroforestry systems.
We consider this book as a tool to improve the collaboration of local communities, farmers and
scientists, as well as to improve the application of scientific knowledge in agricultural practice -
particularly in tropical land use areas.
Bea Maas, the first author of this book, is postdoctoral researcher at the University of Vienna
(Austria), working in the fields of biology, ecology and conservation. She conducted the research and
workshops presented here in close collaboration and with support from the University of Göttingen
(Germany) and the University of Tadulako (Indonesia).Sistem agroforestri kakao adalah hal umum di Indonesia, tetapi perbedaan pengelolaan setempat
akan mempengaruhi keanekaragaman hayati dan layanan ekosistem. Terutama, burung dan kelelawar
sama-sama memberikan kontribusi tinggi pada pengendalian hama biologis di kakao, sehingga
dapat meningkatkan hasil panen dan pertanian yang berkelanjutan. Temuan kami dari penelitian
lapangan ekologi bertahun-tahun, yang bekerjasama erat dengan petani kakao Indonesia, dirangkum
dan dibahas dalam buku bilingual ini, tertulis dalam bahasa Inggris dan bahasa Indonesia. Buku
ini dirancang untuk mengkomunikasikan informasi ilmiah dan juga untuk memfasilitasi diskusi
transdisipliner dan pengelolaan keanekaragaman hayati yang ramah pada sistem agroforestri tropis.
Kami menganggap buku ini sebagai alat untuk meningkatkan kolaborasi masyarakat lokal, petani
dan ilmuwan, serta untuk meningkatkan penerapan pengetahuan ilmiah dalam praktik pertanian -
terutama di wilayah penggunaan lahan tropis.
Bea Maas, penulis pertama buku ini, adalah peneliti postdoctoral di Universitas Wina (Austria),
bekerja di bidang biologi, ekologi dan konservasi. Dia melakukan penelitian dan lokakarya yang
disampaikan dalam buku ini dengan kerjasama yang erat dan dukungan dari Universitas Göttingen
(Jerman) dan Universitas Tadulako (Indonesia)
Trait-dependent responses of birds and bats to season and dry forest distance in tropical agroforestry
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