Drought exerts a strong influence on tropical forest metabolism, carbon stocks, and ultimately the flux of carbon to the atmosphere. Satellite-based studies have suggested that Amazon forests green up during droughts because of increased sunlight, whereas field studies have reported increased tree mortality during severe droughts. In an effort to reconcile these apparently conflicting findings, we conducted an analysis of climate data, field measurements, and improved satellite-based measures of forest photosynthetic activity. Wet-season precipitation and plant-available water (PAW) decreased over the Amazon Basin from 1996−2005, and photosynthetically active radiation (PAR) and air dryness (expressed as vapor pressure deficit, VPD) increased from 2002-2005. Using improved enhanced vegetation index (EVI) measurements (2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008), we show that gross primary productivity (expressed as EVI) declined with VPD and PAW in regions of sparse canopy cover across a wide range of environments for each year of the study. In densely forested areas, no climatic variable adequately explained the Basin-wide interannual variability of EVI. Based on a site-specific study, we show that monthly EVI was relatively insensitive to leaf area index (LAI) but correlated positively with leaf flushing and PAR measured in the field. These findings suggest that production of new leaves, even when unaccompanied by associated changes in LAI, could play an important role in Basin-wide interannual EVI variability. Because EVI variability was greatest in regions of lower PAW, we hypothesize that drought could increase EVI by synchronizing leaf flushing via its effects on leaf bud development.drought | enhanced vegetation index | moderate-resolution imaging spectroradiometer | tropical | carbon cycling

Large-scale wildfires are expected to accelerate forest dieback in Amazô nia, but the fire vulnerability of tree species remains uncertain, in part due to the lack of studies relating fire-induced mortality to both fire behavior and plant traits. To address this gap, we established two sets of experiments in southern Amazonia. First, we tested which bark traits best predict heat transfer rates (R) through bark during experimental bole heating. Second, using data from a large-scale fire experiment, we tested the effects of tree wood density (WD), size, and estimated R (inverse of cambium insulation) on tree mortality after one to five fires. In the first experiment, bark thickness explained 82% of the variance in R, while the presence of water in the bark reduced the difference in temperature between the heat source and the vascular cambium, perhaps because of high latent heat of vaporization. This novel finding provides an important insight for improving mechanistic models of fire-induced cambium damage from tropical to temperate regions. In the second experiment, tree mortality increased with increasing fire intensity (i.e. as indicated by bark char height on tree boles), which was higher along the forest edge, during the 2007 drought, and when the fire return interval was 3 years instead of one. Contrary to other tropical studies, the relationship between mortality and fire intensity was strongest in the year following the fires, but continued for 3 years afterwards. Tree mortality was low ( 20%) for thick-barked individuals ( ! 18 mm) subjected to medium-intensity fires, and significantly decreased as a function of increasing tree diameter, height and wood density. Hence, fire-induced tree mortality was influenced not only by cambium insulation but also by other traits that reduce the indirect effects of fire. These results can be used to improve assessments of fire vulnerability of tropical forests.

The effect of Ca and phytase on phytate phosphorus (PP) hydrolysis was studied in vitro and in vivo. In vitro, PP hydrolysis by a 3-phytase and a 6-phytase was studied at pH 2.5 and 6.5 with Ca added at levels equivalent to 0, 0.1, 0.2, 0.4, 0.7, or 0.9% of the diet. Irrespective of enzyme, Ca at a level as low as 0.1% reduced (P < 0.05) PP hydrolysis at pH 6.5. To test these effects in vivo, 22-d-old male broilers were fed 1 of 6 diets (10 replicate pens of 4 birds per diet) for 30 h. The experimental design was a 3 x 2 factorial arrangement of 3 phytase treatments (0, 500 U of phytase A/kg of diet, and 500 U of phytase B/kg of diet) and 2 added Ca levels (0 and 0.5% from CaCO3) to a corn-soy basal diet. Adding Ca to the diet resulted in a reduction (P < 0.05) in ileal PP disappearance from 69.2 to 25.4% when the 0 and 0.5% added Ca diets were fed, respectively, and in apparent ileal Ca and P absorption (46.3 to 33.6% and 67.9 to 29.4% when 0 and 0.5% Ca were added, respectively). Inclusion of a 3-phytase improved (P < 0.05) ileal PP disappearance from 25.4 to 58.9% in diets containing 0 and 0.5% added Ca, but the improvement was less pronounced with a 6-phytase. Apparent ileal Ca absorption was improved (P < 0.05) when Ca, phytase, or both were added to the diet.

We assembled a list of obligate cave‐dwelling species and subspecies, their county distribution, and their provisional global conservation rank. A total of 927 species and 46 additional subspecies in 96 families exclusively from cave and associated subterranean habitats have been described in the 48 contiguous states of the United States. The terrestrial (troglobitic) species are concentrated in northeast Alabama (especially Jackson County), with other concentrations in Kentucky, Texas, Virginia, and West Virginia. Only 23 counties, comprising less than 1% of the land area of the 48 contiguous states, account for over 50% of the terrestrial species and subspecies. The aquatic (stygobitic) species are concentrated in Hays County, Texas, with other concentrations in Florida, Oklahoma, Texas, Virginia, and West Virginia. Only 18 counties, comprising less than 1% of the land area, account for over 50% of the aquatic species and subspecies. Endemism is high, with 54% of the species known from a single county. Approximately 95% of the species are listed by The Nature Conservancy as vulnerable or imperiled in the United States. These cave species comprise 50% of all vulnerable or imperiled species listed in databases of the Natural Heritage Program. Less than 4% of these subterranean species have federal status. Conservation can best be accomplished through habitat protection, which must include protection of the associated surface habitat.

Aim  Over 250 species of obligate terrestrial cave‐dwelling animals (troglobionts) are known from single caves in the eastern United States. We investigate their geographical distribution, especially in relation to other troglobionts. We relate these patterns to taxonomic group, opportunities for dispersal and geographical location. Location  Caves of the United States east of the Mississippi River. Methods  We associated over 3000 records of more than 450 troglobiotic species and subspecies with hexagons of 1000, 5000 and 10,000 km2 in size. We calculated Moran's I, black–white joins and cubic regression of endemics on non‐endemics at all three spatial scales. For 5000 km2 hexagons, we modelled the spatial autocorrelation of the residuals of the cubic regression of endemics on non‐endemics. Results  Differences among orders in percentage single‐cave endemism were not significant, except for Pseudoscorpionida, which was higher (69%) than any other order. At all three scales, Moran's I and black–white joins were significant, indicating a clumped distribution of both single‐cave endemics and other troglobionts. Spatial patterns were similar at all three scales and Moran's I was highest at 5000 km2. The cubic fit of endemics to non‐endemics was consistently better, with less systematic error or residuals, than were linear or quadratic models. Residuals showed a significant geographical pattern with excess endemics in more southerly locations. Main conclusions  There was both a non‐spatial and spatial component to the pattern of single‐cave endemism. The non‐spatial component was the association of high levels of single‐cave endemism with areas of high diversity of non‐endemics. It may be that both are high because of high secondary productivity. Spatially, single‐cave endemism is high in central rather than peripheral areas and in the southern part of the range. It is not higher in areas of more dissected limestone, which would reduce migration rates; if anything endemism is lower. Regional spatial effects are important, indicating that cave communities cannot be understood (or protected) in isolation.

Determining habitat requirements for threatened primates is critical to implementing conservation strategies, and plans incorporating metapopulation structure require understanding the potential of available habitats to serve as corridors. We examined how three groups of golden-headed lion tamarins Leontopithecus chrysomelas in Southern Bahia, Brazil, used mature, swamp, secondary and shade cocoa (cabruca) forests. Unlike callitrichids that show affinities for degraded forest, Leontopithecus species are presumed to depend on primary or mature forests for sleeping sites in tree holes and epiphytic bromeliads for animal prey. In this study we quantified resource availability within each habitat, compared the proportion of time spent in each habitat to that based on availability, investigated preferences for sleeping site selection, and determined how goldenheaded lion tamarins allocated time to foraging behaviour in different habitats. Each group preferred to range in certain habitats during the day, yet patterns were not consistent across groups. In contrast, all groups preferred to sleep in mature or cabruca forest. Golden-headed lion tamarins spent a greater proportion of time foraging and eating fruits, flowers and nectar in cabruca than in mature or secondary forests. Although the extent to which secondary and cabruca forests can completely sustain breeding groups is unresolved, we conclude that both habitats would make suitable corridors for the movement of tamarins between forest fragments, and that the large trees remaining in cabruca are important sources of food and sleeping sites. We suggest that management plans for golden-headed lion tamarins should focus on protecting areas that include access to tall forest, either as mature or cabruca, for the long-term conservation of the species.

Aim The goal of this study was to determine the role habitat availability plays in the distribution of obligate subterranean cave fauna in eastern North America. Location The numbers of stygobites, troglobites and caves in the counties of the south‐eastern USA were analysed. Methods The data were characterized by large numbers of zeroes and by spatial clustering of non‐zeroes in five regions. Regression and conditional autoregressive (CAR) models were used to elucidate the patterns and relationships between numbers of species and numbers of caves both locally and regionally. Results Local effects (regions and numbers of caves in counties) accounted for 45% of the variation in troglobite counts (P=< 0.001) and 24% of the variation in stygobite counts (P=< 0.001). Significant spatial autocorrelation among both stygobites and troglobites (P=< 0.0001) was found as well. Conclusion Overall, habitat availability as measured by cave numbers influenced species richness. Spatial and regional effects also played an important role in determining the observed distributions of the subterranean fauna. Terrestrial and aquatic communities showed very different patterns in their relationship to habitat and within the different regions.

SUMMARY1. This paper is a synthesis of a special issue on groundwater biodiversity with a focus on obligate subterranean species, the stygobionts. The series of papers constitutes a great leap forward in assessing and understanding biodiversity patterns because of the use of large quantitative data sets obtained over a broad geographic scale. They also represent a conceptual shift, away from a purely taxonomic and phylogenetic focus to the analysis of whole groundwater assemblages. 2. The general patterns emerging for groundwater fauna are: very high levels of endemism, low local diversity relative to regional diversity, a limited number of lineages, occurrence of many relicts, and truncated food webs with very few predators. 3. b-Diversity is at least as important as a-diversity in determining total richness at different scales (aquifer, basin and region) and overall taxa richness increases across spatial scales. 4. Advances in understanding groundwater biodiversity patterns further include identification of several important factors related to geology and hydrology that determine the composition of European stygobiotic assemblages. 5. Important challenges for future research include improving sampling strategies, filling gaps in sampling coverage, intensifying research on theoretical and statistical models, and including functional and genetic diversity components in biodiversity assessments. 6. Strategies are proposed for protecting groundwater biodiversity and an argument is made to integrate biodiversity in groundwater management. Applying principles such as complementarity and flexibility for groundwater biodiversity conservation is a major step toward delineating a reserve network that maximise species representation at the European scale.