No abstract

The increasing expansion of productive lands around the world during the last decades constitutes a strong driver of biodiversity loss, as they are usually established near to high diversity areas. Despite many studies that have compared bird diversity between natural and productive systems, a global synthesis is still missing and important for understanding how biodiversity is being altered. We conducted a meta‐analysis based on 144 case studies to assess the effects of four types of plantations (forestry, oil palm, coffee, and cacao) on bird species richness and abundance. We examined those effects in function of plantation type, latitudinal zone (temperate or tropical), geographical context (mainland or island), zoogeographic zone, and biodiversity hotspots. Plantations presented negative effects on both bird species richness and abundance. Oil palm plantations showed more negative effects followed by forestry plantations, whereas coffee and cacao agroforestry plantations had no significant effects. Those effects were geographically variable, being more pronounced in islands and temperate zones, as well as at the Oriental, Palearctic, and Neotropical zoogeograghic regions, and at the Sundaland and Mediterranean Basin biodiversity hotspots. Our results showed that productive systems reduce both species richness and abundance of bird species, being insular species particularly susceptible. Exotic monocultures with low structural heterogeneity (e.g., oil palm plantations) derive in highly impoverished bird communities dominated by generalist species. We identified South East Asia, tropical South America, and the Mediterranean Basin as the most threatened regions because of the sensitivity of their bird communities and the increasing rates of native forest replacement.

1. Because of continuing degradation or deforestation in areas of undisturbed primary forest, there is a need to study the relative merit of strategies that mitigate their impacts on biodiversity and associated ecological functionality.2. Here, we provide a global synthesis of forest degradation or deforestation using 48 studies published in peer-reviewed journals that use dung beetles as indicators given their sensitivity to anthropogenic disturbance and their relevance in performing essential ecological functions in terrestrial ecosystems.3. We evaluated forest cover associated with undisturbed primary forest degradation (i.e. degraded primary forest) and undisturbed primary forest deforestation (i.e. secondary forest, forestry plantations and forestry restoration implementation) on species richness, total abundance, biomass, functional groups' presence and ecological functions provided by dung beetles. Additionally, we determined whether if dung beetle responses to forest disturbances were geographically dependent.4. We found lower diversity and a decrease in ecological functions associated with all classes of disturbance in primary forest. However, the effects were less severe in the case of forest degradation compared to complete deforestation with natural regeneration of secondary forest, development of forest plantations or active forest restoration by planting indigenous trees. The Neotropical and Oriental regions are particularly vulnerable, given the elevated rates of undisturbed primary forest deforestation and its negative impact on their assemblages' diversity and ecological functions.

Dams are crucial for water supply in human populations and are becoming more common globally for hydroelectric power generation. Dams alter natural habitats and their biodiversity; however, studies are inconclusive about their effects on them. This study aimed to examine the effects of dams on vertebrates and the determinants of changes in global biodiversity and their relationship with critical areas for conservation. We evaluated the effects of dams on vertebrate richness and abundance. We performed a meta-analysis based on 120 case studies. We evaluated the overall effect on richness and abundance and examined these effects regarding taxa, disturbance type, latitudinal zone, zoogeographic zone, biodiversity hotspots, dam size and purpose, and species extinction risk. We conducted an overall analysis that included all species, and then we conducted separate analyses for terrestrial and aquatic species. Dams had a negative effect on vertebrate richness but not on vertebrate abundance. These effects were influenced by larger dams with fragmentation and were more pronounced within hotspots and in countries with a low species extinction risk. Such negative effects were explained by terrestrial vertebrates (particularly birds and mammals) because species richness and the abundance of aquatic vertebrates (fish) were not affected by dams in any case. Our results showed that habitat fragmentation created by large dams changes vertebrate communities, negatively affecting species richness in some areas of conservation concern. We propose implementing reservoirs in areas where they would have a lower impact on biodiversity and avoiding large dams in priority areas for conservation and where endangered species inhabit.

The Colombian Tropical Andes are one of the regions with highest bird diversity on Earth. However, information on bird morphology, reproductive phenology, and molt is particularly scarce in this region. Also, this region is heavily impacted by deforestation, and it is vulnerable to climate change. Hence, providing baseline information on life history and morphological traits will be essential to support future research on functional diversity, climate change effects, conservation, evolution, and phenology. To fill this gap, we have compiled information on bird distribution, morphology, molt, and reproductive phenology at 52 localities of the Department of Caldas, covering an elevation range between 148 and 3845 m. This compilation comprises a wide range of habitats, including native forests, forestry plantations, croplands, and paramo. Our database presents information for 3,398 records belonging to 379 bird species (representing 23 orders, 53 families, and 258 genera). From those records, 2,843 correspond to information collected in the field between 2008 and 2019, and the remaining 555 records correspond to specimens deposited in the Natural History Museum of the Caldas University, collected between 1969 and 2014. We measured nine morphological traits from all specimens: total culmen, gape, bill width, bill depth, tarsus, wing length, tail length, total length, and mass. We also have reproductive condition information for 257 species and molt information available for 378 species. The information contained in this data set represents~20% of the Colombian avifauna and~11% of the bird species richness in South America. This data set is released for non-commercial use only. Credits should be given to this paper (i.e., proper citation), and the products generated with this database should be shared under the same license terms (CC BY-NC-SA).