Identifying drivers of deforestation in tropical biodiversity hotspots is critical to assess threats to particular ecosystems and species and proactively plan for conservation. We analyzed land cover change between 2002 and 2007 in the northern Andes, Chocó, and Amazon forests of Colombia, the largest producer of coca leaf for the global cocaine market, to quantify the impact of this illicit crop on forest dynamics, evaluate the effectiveness of protected areas in this context, and determine the effects of eradication on deforestation. Landscape-level analyses of forest conversion revealed that proximity to new coca plots and a greater proportion of an area planted with coca increased the probability of forest loss in southern Colombia, even after accounting for other covariates and spatial autocorrelation. We also showed that protected areas successfully reduced forest conversion in coca-growing regions. Neither eradication nor coca cultivation predicted deforestation rates across municipalities. Instead, the presence of new coca cultivation was an indicator of municipalities, where increasing population led to higher deforestation rates. We hypothesize that poor rural development underlies the relationship between population density and deforestation in coca-growing areas. Conservation in Colombia's vast forest frontier, which overlaps with its coca frontier, requires a mix of protected areas and strategic rural development to succeed.
Aim Climate change is expected to increase the frequency and intensity of extreme climatic events, such as severe droughts and intense rainfall periods. We explored how the avifauna of a highly modified region responded to a 13year drought (the 'Big Dry'), followed by a two-year period of substantially higher than average rainfall (the 'Big Wet').Location Temperate woodlands in north central Victoria, Australia.Methods We used two spatially extensive, long-term survey programmes, each of which was repeated three times: early and late in the Big Dry, and in the Big Wet. We compared species-specific changes in reporting rates between periods in both programmes to explore the resistance (the ability to persist during drought) and resilience (extent of recovery post-drought) of species to climate extremes. ResultsThere was a substantial decline in the reporting rates of 42-62% (depending on programme) of species between surveys conducted early and late in the Big Dry. In the Big Wet, there was some recovery, with 21-29% of species increasing substantially. However, more than half of species did not recover and 14-27% of species continued to decline in reporting rate compared with early on in the Big Dry. Species' responses were not strongly related to ecological traits. Species resistance to the drought was inversely related to resilience in the Big Wet for 20-35% of the species, while 76-78% of species with low resistance showed an overall decline across the study period.Conclusions As declines occurred largely irrespective of ecological traits, this suggests a widespread mechanism is responsible. Species that declined the most during the Big Dry did not necessarily show the greatest recoveries. In already much modified regions, climate extremes such as extended drought will induce on-going changes in the biota.
Body size is an integral functional trait that underlies pollination‐related ecological processes, yet it is often impractical to measure directly. Allometric scaling laws have been used to overcome this problem. However, most existing models rely upon small sample sizes, geographically restricted sampling and have limited applicability for non‐bee taxa. Allometric models that consider biogeography, phylogenetic relatedness, and intraspecific variation are urgently required to ensure greater accuracy. We measured body size as dry weight and intertegular distance (ITD) of 391 bee species (4,035 specimens) and 103 hoverfly species (399 specimens) across four biogeographic regions: Australia, Europe, North America, and South America. We updated existing models within a Bayesian mixed‐model framework to test the power of ITD to predict interspecific variation in pollinator dry weight in interaction with different co‐variates: phylogeny or taxonomy, sexual dimorphism, and biogeographic region. In addition, we used ordinary least squares regression to assess intraspecific dry weight ~ ITD relationships for ten bees and five hoverfly species. Including co‐variates led to more robust interspecific body size predictions for both bees and hoverflies relative to models with the ITD alone. In contrast, at the intraspecific level, our results demonstrate that the ITD is an inconsistent predictor of body size for bees and hoverflies. The use of allometric scaling laws to estimate body size is more suitable for interspecific comparative analyses than assessing intraspecific variation. Collectively, these models form the basis of the dynamic R package, “ pollimetry, ” which provides a comprehensive resource for allometric pollination research worldwide.
Summary Ecosystems world‐wide increasingly are subject to multiple interacting disturbances. Biodiversity in anthropogenic landscapes can be enhanced by manipulating landscape patterns, but could such landscape management also assist biota to cope with the effects of extreme climatic events, such as drought? We surveyed woodland bird communities in 24 ‘whole’ landscapes (each 100 km2) in an agricultural region of south‐eastern Australia near the beginning (2002–2003), middle (2006–2007) and after (2011–2012) an extreme drought (the ‘Millennium Drought’). We quantified the resistance, resilience and stability of the avifauna to the decade of drought and related these measures to properties of the study landscapes: the extent of wooded habitat, configuration of habitat, land‐use composition, landscape productivity and geographic context. Landscape productivity, represented by the extent of riparian tree cover in the landscape, was the strongest driver of the resistance, resilience and stability of avifaunal richness to severe drought. Woodland bird communities in landscapes with larger areas of riparian tree cover retained a larger proportion of their species richness during the Millennium Drought and consequently had greater stability over the drought's duration. Synthesis and applications. Landscape properties can influence the resistance, resilience and stability of faunal communities to an extreme climatic event. By protecting, restoring and enhancing native vegetation in productive areas of landscapes along stream systems, drainage lines and floodplains, land managers can effectively build climatic refugia and thereby enhance the resistance of biota to climatic extremes. However, a net decline over the entire study period suggests this will not, by itself, arrest decline during periods of extreme drought.
Wild and managed bees provide effective crop pollination services worldwide. Protected cropping conditions are thought to alter the ambient environmental conditions in which pollinators forage for flowers, yet few studies have compared conditions at the edges and center of growing tunnels. We measured environmental variables (temperature, relative humidity, wind speed, white light, and UV light) and surveyed activity of the managed honey bee, Apis mellifera L.; wild stingless bee, Tetragonula carbonaria Smith; and wild sweat bee, Homalictus urbanus Smith, along the length of 32 multiple open-ended polyethylene growing tunnels. These were spaced across 12 blocks at two commercial berry farms, in Coffs Harbour, New South Wales and Walkamin, North Queensland, Australia. Berry yield, fresh weight, and other quality metrics were recorded at discrete increments along the length of the tunnels. We found a higher abundance and greater number of flower visits by stingless bees and honey bees at the end of tunnels, and less frequent visits to flowers toward the middle of tunnels. The center of tunnels experienced higher temperatures and reduced wind speed. In raspberry, fruit shape was improved with greater pollinator abundance and was susceptible to higher temperatures. In blueberry, per plant yield and mean berry weight were positively associated with pollinator abundance and were lower at the center of tunnels than at the edge. Fruit quality (crumbliness) in raspberries was improved with a greater number of visits by sweat bees, who were not as susceptible to climatic conditions within tunnels. Understanding bee foraging behavior and changes to yield under protected cropping conditions is critical to inform the appropriate design of polytunnels, aid pollinator management within them, and increase economic gains in commercial berry crops.
Pan trapping is a common method for sampling wild bees, although the use of vane traps is growing globally. Despite this, few studies have tested the effectiveness of different coloured vane traps in attracting bees among different habitat types, and none exist in the southern hemisphere. The present study sampled 192 sites (108 in wooded habitats and 84 in open habitats) within an agricultural region of southern Australia. Pairs of coloured vane traps (one blue and one yellow) were placed at each site for a period of seven days. Combined, 16 348 individuals were collected from four families, comprising 13 genera (21 subgenera) and 55 species. Blue vane taps were most effective, sampling six times as many individuals as yellow vane traps and 96% of total species. Their effectiveness was consistent among open and wooded habitat types. The present study highlights the efficacy of vane traps as a passive sampling technique for wild bees. An added benefit of this technique is that vane traps do not require pheromones or lethal agents. A systematic sampling method best suited to the research question should be incorporated into studies of wild bees. For ecological census and population monitoring within multiple habitat types, the present study supports the use of blue vane taps as a major component of the sampling protocol.
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