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Tropical forests are often characterized by low soil phosphorus (P) availability, suggesting that P limits plant performance. However, how seedlings from different functional types respond to soil P availability is poorly known but important for understanding and modeling forest dynamics under changing environmental conditions. We grew four nitrogen (N)-fixing Fabaceae and seven diverse non-N-fixing tropical dry forest tree species in a shade house under three P fertilization treatments and evaluated carbon (C) allocation responses, P demand, P-use, investment in P acquisition traits, and correlations among P acquisition traits. Nitrogen fixers grew larger with increasing P addition in contrast to non-N fixers, which showed fewer responses in C allocation and P use. Foliar P increased with P addition for both functional types, while P acquisition strategies did not vary among treatments but differed between functional types, with N fixers showing higher root phosphatase activity (RPA) than nonfixers. Growth responses suggest that N fixers are limited by P, but nonfixers may be limited by other resources. However, regardless of limitation, P acquisition traits such as mycorrhizal colonization and RPA were nonplastic across a steep P gradient. Differential limitation among plant functional types has implications for forest succession and earth system models.

Sensitivity of forest mortality to drought in carbon-dense tropical forests remains fraught with uncertainty, while extreme droughts are predicted to be more frequent and intense. Here, the potential of temporal autocorrelation of high-frequency variability in Landsat Enhanced Vegetation Index (EVI), an indicator of ecosystem resilience, to predict spatial and temporal variations of forest biomass mortality is evaluated against in situ census observations for 64 site-year combinations in Costa Rican tropical dry forests during the 2015 ENSO drought. Temporal autocorrelation, within the optimal moving window of 24 months, demonstrated robust predictive power for in situ mortality (leave-one-out cross-validation R

Despite their low contribution to forest carbon stocks, lianas (woody vines) play an important role in the carbon dynamics of tropical forests. As structural parasites, they hinder tree survival, growth and fecundity; hence, they negatively impact net ecosystem productivity and long‐term carbon sequestration.Competition (for water and light) drives various forest processes and depends on the local abundance of resources over time. However, evaluating the relative role of resource availability on the interactions between lianas and trees from empirical observations is particularly challenging. Previous approaches have used labour‐intensive and ecosystem‐scale manipulation experiments, which are infeasible in most situations.We propose to circumvent this challenge by evaluating the uncertainty of water and light capture processes of a process‐based vegetation model (ED2) including the liana growth form. We further developed the liana plant functional type in ED2 to mechanistically simulate water uptake and transport from roots to leaves, and start the model from prescribed initial conditions. We then used the PEcAn bioinformatics platform to constrain liana parameters and run uncertainty analyses.Baseline runs successfully reproduced ecosystem gas exchange fluxes (gross primary productivity and latent heat) and forest structural features (leaf area index, aboveground biomass) in two sites (Barro Colorado Island, Panama and Paracou, French Guiana) characterized by different rainfall regimes and levels of liana abundance.Model uncertainty analyses revealed that water limitation was the factor driving the competition between trees and lianas at the drier site (BCI), and during the relatively short dry season of the wetter site (Paracou). In young patches, light competition dominated in Paracou but alternated with water competition between the wet and the dry season on BCI according to the model simulations.The modelling workflow also identified key liana traits (photosynthetic quantum efficiency, stomatal regulation parameters, allometric relationships) and processes (water use, respiration, climbing) driving the model uncertainty. They should be considered as priorities for future data acquisition and model development to improve predictions of the carbon dynamics of liana‐infested forests. Synthesis. Competition for water plays a larger role in the interaction between lianas and trees than previously hypothesized, as demonstrated by simulations from a process‐based vegetation model., Competition for water plays a larger role in the interaction between lianas and trees than previously hypothesized, as demonstrated by simulations from a process‐based vegetation model.

There are two theories about how allocation of metabolic products occurs. The allometric biomass partitioning theory (APT) suggests that all plants follow common allometric scaling rules. The optimal partitioning theory (OPT) predicts that plants allocate more biomass to the organ capturing the most limiting resource. Whole-plant harvests of mature and juvenile tropical deciduous trees, evergreen trees, and lianas and model simulations were used to address the following knowledge gaps: (1) Do mature lianas comply with the APT scaling laws or do they invest less biomass in stems compared to trees? (2) Do juveniles follow the same allocation patterns as mature individuals? (3) Is either leaf phenology or life form a predictor of rooting depth? It was found that: (1) mature lianas followed the same allometric scaling laws as trees; (2) juveniles and mature individuals do not follow the same allocation patterns; and (3) mature lianas had shallowest coarse roots and evergreen trees had the deepest. It was demonstrated that: (1) mature lianas invested proportionally similar biomass to stems as trees and not less, as expected; (2) lianas were not deeper-rooted than trees as had been previously proposed; and (3) evergreen trees had the deepest roots, which is necessary to maintain canopy during simulated dry seasons.

Many studies have examined individual environmental drivers of tropical tree species distributions, but edaphic and successional gradients have not been considered simultaneously. Furthermore, determining how functional traits influence species distributions along these gradients may help to elucidate mechanisms behind community assembly. To assess the influence of environmental filtering on tropical dry forest (TDF) tree species distributions, we used forest inventory data from sites with large edaphic and successional gradients in NW Costa Rica. Our goals were to determine (1) whether edaphic or successional factors are more important determinants of the abundance of individual tree species in regenerating TDF, (2) how species‐level functional traits are related to edaphic and/or successional niche associations of tree species and (3) correlations between species‐level edaphic and successional niche associations. The distributions of 82 focal tree species were strongly driven by both edaphic and successional gradients. Overall, 94% of species responded to soil chemistry, 89% to soil texture and 94% to stand age gradients. Some functional traits were correlated with the edaphic and successional niche associations of TDF tree species. Species that specialized on soils with high total nutrient concentrations had higher foliar nutrient concentrations (nitrogen and phosphorus) and lower leaf dry matter content (LDMC). Species with wider stand age niches had lower LDMC and wood density. There were no correlations between edaphic and successional niche optima of TDF tree species. Our results indicate that successional and edaphic gradients concurrently drive community assembly in regenerating TDF. Moreover, our work underscores the importance of considering how the functional characteristics of TDF trees dictate species distributions across environmental gradients. A plain language summary is available for this article.

Tropical dry forests (TDFs) are critically endangered, and their restoration is understudied. Large-scale passive restoration efforts in north-west (NW) Costa Rica have catalysed TDF regeneration but are not effective on degraded Vertisols, where active restoration is necessary due to high content of shrink–swell clays that impede regeneration following degradation. We established a large-scale restoration experiment in degraded former pastures in NW Costa Rica to determine (1) the restoration potential of native TDF tree species on Vertisols, (2) if plant functional traits elucidate mechanisms behind interspecific variability in species performance and (3) if affordable and readily available soil amendments increase seedling survivorship and growth. We planted 1,710 seedlings of 32 native species coupled with five amendments aimed at ameliorating root-zone microclimatic conditions: sand, rice hulls, rice hull ash, hydrogel and unamended controls. For each species, we quantified a suite of resource-acquisition and ecophysiological functional traits, and monitored survival and growth seasonally over 2 years. Interspecific survivorship after 2 years ranged widely (0%–92.5%). Functional traits including wood density, photosynthetic parameters and upregulation of integrated water-use efficiency, explained interspecific variation in survivorship and growth at distinct ontogenetic stages. Easily measured leaf traits, however, were not good predictors of restoration potential. Hydrogel and sand amendments increased initial seedling survival, but after 2 years no differences among treatments were found. Synthesis and applications. We have shown it is possible, albeit challenging, to restore tropical dry forest (TDF) on degraded Vertisols. Our results support the use of functional trait-based screenings to select tree species for restoration projects as tree species with high survivorship and growth in this stressful environment have overlapping ecophysiological functional traits. Furthermore, practitioners should consider water-use and phytosynthetic traits when designing initial species mixes for TDF restorations.

Lower-cost tropical forest restoration methods, particularly those framed as win–win business-protected area partnerships, could dramatically increase the scale of tropical forest restoration activities, thereby providing a variety of societal and ecosystem benefits, including slowing both global biodiversity loss and climate change. Here we describe the long-term regenerative effects of a direct application of agricultural waste on tropical dry forest. In 1998, as part of an innovative agricultural waste disposal service contract, an estimated 12,000 Mg of processed orange peels and pulp were applied to a 3 ha portion of a former cattle pasture with compacted, rocky, nutrient-poor soils characteristic of prolonged fire-based land management and overgrazing in Area de Conservacion Guanacaste, northwestern Costa Rica. After 16 years, the experimental plot showed a threefold increase in woody plant species richness, a tripling of tree species evenness (Shannon Index), and a 176% increase in aboveground woody biomass over an adjacent control plot. Hemispheric photography showed significant increases in canopy closure in the area where orange waste was applied relative to control. Orange waste deposition significantly elevated levels of soil macronutrients and important micronutrients in samples taken 2 and 16 years after initial orange waste application. Our results point to promising opportunities for valuable synergisms between agricultural waste disposal and tropical forest restoration and carbon sequestration.

Lianas are a key component of tropical forests, where they compete intensely with trees, reducing tree recruitment, growth and survival. One of the most important potential outcomes of liana competition is the reduction of tree reproduction; however, no previous study has experimentally determined the effects of lianas on tree reproduction beyond a single tree species. We used a large-scale liana removal experiment to quantify the effect of lianas on community-level canopy and understorey tree and palm reproduction. In 2011, we removed lianas from eight 6,400-m2 plots (eight plots served as controls) and surveyed understorey tree reproduction in 2012, canopy tree and palm reproduction in 2013, and a second census of all plants in 2016. We found that lianas significantly reduced canopy tree community flowering and fruiting after liana removal. Two years after liana removal, the number of canopy trees with fruits was 173% higher, fruiting individuals had 50% more of their canopy covered by fruits and the number of tree species with fruits was 169% higher than in control plots where lianas were present. Five years after liana removal, the number of canopy trees with fruits was 150% higher, fruiting individuals had 31% more of their canopy covered by fruits and the number of tree species with fruits was 109% higher than in unmanipulated control plots. Liana removal had only a slight positive effect on palms and on understorey tree flower and fruit production, even though understorey light levels had increased 20% following liana cutting. Synthesis. Our findings provide the first experimental demonstration that competition from lianas significantly reduces community-level canopy tree reproduction. Reduced reproduction increases canopy tree seed and dispersal limitations, and may interfere with deterministic mechanisms thought to maintain tropical canopy tree species diversity, as well as reduce food availability to many animal species. Because lianas are increasing in abundance in many neotropical forests, the effects of lianas on tree reproduction will likely increase, and if the effects of lianas on tree reproduction vary with tree species identity, lianas ultimately could have a destabilizing effect on both tree and animal population dynamics.

PREMISE OF THE STUDY The seedling stage is particularly vulnerable to resource limitation, with potential consequences for community composition. We investigated how light and soil variation affected early growth, biomass partitioning, morphology, and physiology of 22 tree species common in tropical dry forest, including eight legumes. Our hypothesis was that legume seedlings are better at taking advantage of increased resource availability, which contributes to their successful regeneration in tropical dry forests. METHODS We grew seedlings in a full-factorial design under two light levels in two soil types that differed in nutrient concentrations and soil moisture. We measured height biweekly and, at final harvest, biomass partitioning, internode segments, leaf carbon, nitrogen, δ13C, and δ15N. KEY RESULTS Legumes initially grew taller and maintained that height advantage over time under all experimental conditions. Legumes also had the highest final total biomass and water-use efficiency in the high-light and high-resource soil. For nitrogen-fixing legumes, the amount of nitrogen derived from fixation was highest in the richer soil. Although seed mass tended to be larger in legumes, seed size alone did not account for all the differences between legumes and nonlegumes. Both belowground and aboveground resources were limiting to early seedling growth and function. CONCLUSIONS Legumes may have a different regeneration niche, in that they germinate rapidly and grow taller than other species immediately after germination, maximizing their performance when light and belowground resources are readily available, and potentially permitting them to take advantage of high light, nutrient, and water availability at the beginning of the wet season.

This study examined the prevalence of reported suicide attempts among family members of individuals with an eating disorder (ED). 1870 individuals presenting for ED treatment reported whether their family members ever made a suicide attempt using the Eating Disorders Questionnaire. A lifetime suicide attempt by any family member was reported by 10.8% (n = 202) of the sample and ranged from 7.0% of those with eating disorder not otherwise specified to 16.1% of those with purging disorder. Controlling for age and gender, individuals with bulimia nervosa had a higher prevalence of any familial suicide attempt and mother suicide attempt than individuals with EDNOS; no other differences were observed across ED diagnoses. There were no differences in prevalence of reported suicide attempts made by fathers, brothers, sisters, uncles, or aunts by ED diagnosis. Findings support a growing literature indicating a familial association between EDs and suicide risk.

Lianas are more abundant in seasonal forests than in wetter forests and are thought to perform better than trees when light is abundant and water is limited. We tested the hypothesis that lianas perform better than trees during seasonal drought using a common garden experiment with 12 taxonomically diverse species (six liana and six tree species) in 12 replicated plots. We irrigated six of the plots during the dry season for four years, while the remaining six control plots received only ambient rainfall. In year 5, we measured stem diameters for all individuals and harvested above- and belowground biomass for a subset of individuals to quantify absolute growth and biomass allocation to roots, stems, and leaves, as well as total root length and maximum rooting depth. We also measured rate of photosynthesis, intrinsic water use efficiency (iWUE), pre-dawn and midday water potential, and a set of functional and hydraulic traits. During the peak of the dry season, lianas in control plots had 54% higher predawn leaf water potentials (ΨPD ), and 45% higher photosynthetic rates than trees in control plots. By contrast, during the peak of the wet season, these physiological differences between lianas and trees become less pronounced and, in some cases, even disappeared. Trees had higher specific leaf area (SLA) than lianas; however, no other functional trait differed between growth forms. Trees responded to the irrigation treatment with 15% larger diameters and 119% greater biomass than trees in control plots. Liana growth, however, did not respond to irrigation; liana diameter and biomass were similar in control and irrigation plots, suggesting that lianas were far less limited by soil moisture than were trees. Contrary to previous hypotheses, lianas did not have deeper roots than trees; however, lianas had longer roots per stem diameter than did trees. Our results support the hypothesis that lianas perform better and experience less physiological stress than trees during seasonal drought, suggesting clear differences between growth forms in response to altered rainfall regimes. Ultimately, better dry-season performance may explain why liana abundance peaks in seasonal forests compared to trees, which peak in abundance in less seasonal, wetter forests.

Naturally regenerating and restored second growth forests account for over 70% of tropical forest cover and provide key ecosystem services. Understanding climate change impacts on successional trajectories of these ecosystems is critical for developing effective large-scale forest landscape restoration (FLR) programs. Differences in environmental conditions, species composition, dynamics, and landscape context from old growth forests may exacerbate climate impacts on second growth stands. We compile data from 112 studies on the effects of natural climate variability, including warming, droughts, fires, and cyclonic storms, on demography and dynamics of second growth forest trees and identify variation in forest responses across biomes, regions, and landscapes. Across studies, drought decreases tree growth, survival, and recruitment, particularly during early succession, but the effects of temperature remain unexplored. Shifts in the frequency and severity of disturbance alter successional trajectories and increase the extent of second growth forests. Vulnerability to climate extremes is generally inversely related to long-term exposure, which varies with historical climate and biogeography. The majority of studies, however, have been conducted in the Neotropics hindering generalization. Effects of fire and cyclonic storms often lead to positive feedbacks, increasing vulnerability to climate extremes and subsequent disturbance. Fragmentation increases forests’ vulnerability to fires, wind, and drought, while land use and other human activities influence the frequency and intensity of fire, potentially retarding succession. Comparative studies of climate effects on tropical forest succession across biogeographic regions are required to forecast the response of tropical forest landscapes to future climates and to implement effective FLR policies and programs in these landscapes.

The carbon use efficiency (CUE) of microbial communities partitions the flow of C from primary producers to the atmosphere, decomposer food webs, and soil C stores. CUE, usually defined as the ratio of growth to assimilation, is a critical parameter in ecosystem models, but is seldom measured directly in soils because of the methodological difficulty of measuring in situ rates of microbial growth and respiration. Alternatively, CUE can be estimated indirectly from the elemental stoichiometry of organic matter and microbial biomass, and the ratios of C to nutrient-acquiring ecoenzymatic activities. We used this approach to estimate and compare microbial CUE in >2000 soils from a broad range of ecosystems. Mean CUE based on C:N stoichiometry was 0.269 ± 0.110 (mean ± SD). A parallel calculation based on C:P stoichiometry yielded a mean CUE estimate of 0.252 ± 0.125. The mean values and frequency distributions were similar to those from aquatic ecosystems, also calculated from stoichiometric models, and to those calculated from direct measurements of bacterial and fungal growth and respiration. CUE was directly related to microbial biomass C with a scaling exponent of 0.304 (95% CI 0.237–0.371) and inversely related to microbial biomass P with a scaling exponent of −0.234 (95% CI −0.289 to −0.179). Relative to CUE, biomass specific turnover time increased with a scaling exponent of 0.509 (95% CI 0.467–0.551). CUE increased weakly with mean annual temperature. CUE declined with increasing soil pH reaching a minimum at pH 7.0, then increased again as soil pH approached 9.0, a pattern consistent with pH trends in the ratio of fungal : bacteria abundance and growth. Structural equation models that related geographic variables to CUE component variables showed the strongest connections for paths linking latitude and pH to β-glucosidase activity and soil C:N:P ratios. The integration of stoichiometric and metabolic models provides a quantitative description of the functional organization of soil microbial communities that can improve the representation of CUE in microbial process and ecosystem simulation models.

More frequent and severe El Nino Southern Oscillations (ENSO) are causing episodic periods of decreased rainfall. Although the effects of these ENSO-induced droughts on tree growth and mortality have been well studied, the impacts on other demographic rates such as reproduction are less well known. We use a four-year seed rain dataset encompassing the most severe ENSO-induced drought in more than 30 years to assess the resilience (i.e., resistance and recovery) of the seed composition and abundance of three forest types in a tropical dry forest. We found that forest types showed distinct differences in the timing, duration, and intensity of drought during the ENSO event, which likely mediated seed composition shifts and resilience. Drought-deciduous species were particularly sensitive to the drought with overall poor resilience of seed production, whereby seed abundance of this functional group failed to recover to predrought levels even two years after the drought. Liana and wind-dispersed species were able to maintain seed production both during and after drought, suggesting that ENSO events promote early successional species or species with a colonization strategy. Combined, these results suggest that ENSO-induced drought mediates the establishment of functional groups and dispersal types suited for early successional conditions with more open canopies and reduced competition among plants. The effects of the ENSO-induced drought on seed composition and abundance were still evident two years after the event suggesting the recovery of seed production requires multiple years that may lead to shifts in forest composition and structure in the long term, with potential consequences for higher trophic levels like frugivores.

Lianas are a common plant growth form in tropical forests, where they compete intensely with trees, decreasing tree recruitment, growth, and survival. If the detrimental effects of lianas vary significantly with tree species identity, as is often assumed, then lianas may influence tree species diversity and community composition. Furthermore, recent studies have shown that liana abundance and biomass are increasing relative to trees in neotropical forests, which will likely magnify the detrimental effects of lianas and may ultimately alter tree species diversity, relative abundances, and community composition. Few studies, however, have tested the responses of multiple tree species to the presence of lianas in robust, well-replicated experiments. We tested the hypotheses that lianas reduce tree seedling growth and survival, and that the effect of lianas varies with tree species identity. We used a large-scale liana removal experiment in Central Panama in which we planted 14 replicate seedlings of 14 different tree species that varied in shade tolerance in each of 16 80 x 80 m plots (eight liana-removal and eight unmanipulated controls; 3136 total seedlings). Over a nearly two-yr period, we found that tree seedlings survived 75% more, grew 300% taller, and had twice the aboveground biomass in liana-removal plots than seedlings in control plots, consistent with strong competition between lianas and tree seedlings. There were no significant differences in the response of tree species to liana competition (i.e., there was no species by treatment interaction), indicating that lianas had a similar negative effect on all 14 tree species. Furthermore, the effect of lianas did not vary with tree species shade tolerance classification, suggesting that the liana effect was not solely based on light. Based on these findings, recently observed increases in liana abundance in neotropical forests will substantially reduce tree regeneration, but will not significantly alter tropical tree species diversity, relative abundance, or community composition.

AN ESTIMATED 8.5 % of Americans suffer from alcohol use disorders (AUDs) in the United States. Estimated costs associated with AUDs exceed $223 billion and approximately 79,000 lives, with approximately 2.3 million years of potential life lost annually (Harwood, 2013). Because the burden of AUDs on society is so great, elucidating the mechanisms involved in the disease progression is critical. More specifically, identifying neurochemical systems involved in alcohol-related behaviors could pave the way for therapeutic targets that will ultimately reduce the burden of AUDs on society. One such system, the endocannabinoid system (ECS), has gained attention in recent years because it appears to play an important role in a variety of neuropsy-chiatric conditions (Abood and Martin, 1992; Hirst et al., 1998; Navarro and Rodriguez de Fonseca, 1998), including AUDs (see reviews by Justinova et al., 2009; Maldonado et al., 2006). The ECS consists of 2 known receptor subtypes (cannabinoid receptor 1 [CB1R] and CB2R), 2 main endogenous ligands that act on these receptors (anandamide [AEA] and 2-arachidonoylglycerol [2-AG]), and the enzymes responsible for endocannabinoid degradation (monoacylglycerol lipase and fatty acid amide hydrolase). CB1R is highly expressed in brain reward circuitry and can regulate the excitatory and inhibitory inputs to the dopaminergic neurons of the mesocorticolimbic reward pathway (see review by Gardner, 2005). CB2Rs are found in a number of tissue and cell types in the periphery, including spleen, tonsils, and immune cells such as microphages and T cells. In the central nervous system, CB2Rs are expressed on neurons and activated microglia (Cabral et al., 2008; Garcia-Gutierrez et al., 2010; Onaivi, 2006). While there is still ongoing debate as to the localization of CB2R in the brain, there is evidence for expression in the caudate putamen, cingulate cortex, amygdala, hippocampus, ventromedial hypothalamic nucleus, arcuate nucleus, thalamus, substantia nigra, dorsal raphe nucleus, medial raphe nucleus, ventral tegmental area (VTA), and the nucleus accumbens (NAc) (Garcia-Gutierrez et al., 2010; Onaivi, 2006). The presence of CB2R in reward-related brain areas (i.e., NAc and VTA) suggests the possible involvement of this receptor in drug reward-related behaviors. Both alcohol and activation of CB1R increase dopamine (DA) levels in the NAc, and cannabinoids (both endogenous and exogenous) can enhance the firing of dopaminergic neurons (Diana et al., 1998; French, 1997; French et al., 1997; Gessa et al., 1998; Hungund et al., 2003). Activation of CB2R has been shown to reduce cocaine-induced extracellular DA release and stimulated locomotor behavior (Xi et al., 2011), as well as reduce VTA DA neuronal firing (Zhang et al., 2014). These data, together with the observed localization of CB2Rs in the VTA, suggest that CB2Rs modulate drug reward-related behaviors. Behavioral evidence further supports a role for CB2R in drug reward-related behaviors. Pharmacological activation of CB2Rs with JWH-133 dose-dependently reduced cocaine self-administration in wild-type (WT) and CB1R knockout (KO) mice, but not in CB2R KO mice (Xi et al., 2011). Similarly, transgenic mice that overexpress CB2Rs self-administered less cocaine than WT controls (Aracil-Fernandez et al., 2012). CB2R KO mice showed reduced nicotine reward-related behaviors (Ignatowska-Jankowska et al., 2013; Navarrete et al., 2013) and pharmacological blockade of CB2Rs with SR144528 reduced nicotine-induced conditioned place preference (CPP) in C57BL/6 mice (Ignatowska-Jankowska et al., 2013). Relevant to the current study with alcohol, Onaivi and colleagues (2008) showed reduced CB2R gene expression in the ventral midbrain region of inbred mice that developed a preference for alcohol compared to inbred mice that did not. In addition, chronic treatment with a CB2R agonist and a CB2R antagonist enhanced and reduced alcohol consumption, respectively, in stressed but not control inbred mice (Ishiguro et al., 2007; Onaivi et al., 2008). CB2R KO mice consumed more alcohol in an unlimited-access 2-bottle choice study and developed more robust alcohol-induced CPP compared to WT littermate controls (Ortega-Alvaro et al., 2015). Also, CB2R activation, via the agonist β caryophyllene, reduced sensitivity to alcohol-induced sedation, alcohol intake, and alcohol-induced CPP in C57BL/6 mice (Al Mansouri et al., 2014). These findings are compelling and suggest that modulation of CB2Rs affects alcohol reward-related behaviors. The purpose of this study was to assess the role of CB2R in modulating alcohol reward-related behaviors in 2 genetic mouse models and using 2 well-established models of alcohol reward: home cage limited-access 2-bottle choice alcohol drinking and alcohol-induced CPP. First, we pharmacologically assessed CB2R involvement in alcohol reward-related behaviors in selectively bred high-alcohol-preferring (HAP2) mice. Evidence suggests that genetic alterations in the ECS, including CB1R, may influence alcohol-related behaviors in rodents (e.g., Cippitelli et al., 2005; Hansson et al., 2007; Hungund and Basavarajappa, 2000). The HAP2 mouse line is a relevant model when studying genetically influenced mechanisms of AUDs in humans. We previously showed that HAP2 mice were more sensitive to pharmacological ECS manipulation compared to their low-alcohol-preferring counterparts (Powers et al., 2010), suggesting that genetic propensity toward high alcohol preference is associated with changes in ECS function. Second, we used mice with genetic deletion of CB2R (CB2R KO) to replicate the findings of Ortega-Alvaro and colleagues (2015) and to compare pharmacological versus genetic approaches in the study of the role of CB2R in alcohol reward-related behaviors. We hypothesized that pharmacological blockade and genetic deletion of CB2Rs would increase alcohol drinking and increase the expression of alcohol-induced CPP based on findings of Ortega-Alvaro and colleagues (2015), who showed that CB2R KO mice developed an alcohol-induced CPP, while WT controls did not.

Objective The major aim of this study was to investigate any association between binge eating and purging and alcohol and substance use. Method The Eating Disorder Questionnaire was completed by 2966 patients. Each patient was assigned to an approximate diagnostic group based on a DSM-5-based algorithm. Results Patients with bulimia nervosa (BN) used alcohol/other substances with higher frequencies compared to patients with anorexia nervosa-restricting type (AN-R), binge eating disorder (BED), and eating disorder not otherwise specified (EDNOS; p

Rates of ecosystem nitrogen (N) cycling may be mediated by the presence of ectomycorrhizal fungi, which compete directly with free-living microbes for N. In the regenerating tropical dry forests of Central America, the distribution of ectomycorrhizal trees is affected by succession and soil parent material, both of which may exert independent influence over soil N fluxes. In order to quantify these interacting controls, we used a scale-explicit sampling strategy to examine soil N cycling at scales ranging from the microsite to ecosystem level. We measured fungal community composition, total and inorganic N pools, gross proteolytic rate, net N mineralization and microbial extracellular enzyme activity at multiple locations within 18 permanent plots that span dramatic gradients of soil N concentration, stand age and forest composition. The ratio of inorganic to organic N cycling was correlated with variation in fungal community structure, consistent with a strong influence of ectomycorrhiza on ecosystem-scale N cycling. However, on average, > 61% of the variation in soil biogeochemistry occurred within plots, and the effects of forest composition were mediated by this local-scale heterogeneity in total soil N concentrations. These cross-scale interactions demonstrate the importance of a spatially explicit approach towards an understanding of controls on element cycling.

To test a new hypothesis explaining Fabaceae success in tropical dry forests, we compared seed germination of 34 species includinglegumes and non-legumes. Legume seeds germinated twice as fast with higher final percentages compared to other taxa, which mayafford them a competitive advantage in highly seasonal environments.Abstract in Spanish is available in the online version of this article. Key words: Costa Rica; Fabaceae; germination rate; plant traits; seed germination; tropical dry forest. S PECIES FROM THE FAMILY F ABACEAE ( THE LEGUMES ) ARE ABUNDANTAND DIVERSE IN TROPICAL FORESTS (Gentry 1988). Legumes are oneof the few plant families with the ability to form symbiotic associ-ations with nitrogen-fixing bacteria (Corby 1988, Quispel 1988),thus, their abundances in plant communities may affect nitrogencycling at the ecosystem scale (Cleveland et al. 1999). Indeed,newly fixed nitrogen by legumes is thought to fuel much of thenet primary production in the tropics (Cleveland et al. 2013),although the magnitude of this process may vary with local soilconditions or climate (Nardoto et al. 2013). However, symbioticnitrogen fixation is energetically expensive, and this process ishypothesized to be down-regulated under conditions of high soilnitrogen availability. As nitrogen availability is generally high inlowland tropical ecosystems (Vitousek & Matson 1988), the highabundances of legumes in tropical forests present a ‘paradox’(Crews 1999, Hedin et al. 2009). This apparent paradox has beenresolved, in part, by assuming that legume trees employ a perfectlyfacultative strategy and only fix nitrogen under conditions of lownitrogen availability (Hedin et al. 2009). However, not all legumesfix nitrogen (Corby 1988), and legumes often differ from othertaxa in ways other than high foliar nitrogen (McKey 1994, Powers& Tiffin 2010). It is therefore possible that traits such as fecundity,dispersal, dormancy, and/or germination, which determine spe-cies’ regeneration niche (Grubb 1977), and not biological N

Author(s): Cook, Brian J; Steffen, Kristine J; Mitchell, James E; Otto, Maxwell; Crosby, Ross D; Cao, Li; Wonderlich, Stephen A; Crow, Scott; Hill, Laura; Le Grange, Daniel; Powers, Pauline | Abstract: ObjectiveThe objective of this study was to investigate diagnostic differences in weight suppression (e.g., the difference between one's current body weight and highest non-pregnancy adult body weight) and exercise among Bulimia Nervosa (BN) and Binge Eating Disorder (BED). Because exercise may be a key contributor to weight suppression in BN, we were interested in examining the potential moderating effect of exercise on weight suppression in BN or BED.MethodParticipants with BN (n = 774) and BED (n = 285) completed self-report surveys of weight history, exercise and eating disorder symptoms. Generalised linear model analyses were used to examine the associations among diagnosis, exercise frequency and their interaction on weight suppression.ResultsExercise frequency and BN/BED diagnosis were both associated with weight suppression. Additionally, exercise frequency moderated the relationship between diagnosis and weight suppression. Specifically, weight suppression was higher in BN than in BED among those with low exercise frequency but comparable in BN and BED among those with high exercise frequency.DiscussionOur results suggest that exercise frequency may contribute to different weight suppression outcomes among BN and BED. This may inform clinical implications of exercise in these disorders. Specifically, much understanding of the differences among exercise frequency and the compensatory use of exercise in BN and BED is needed.

Repetitive stimulation of the Drosophila larval NMJ can produce a reduction in the frequency of miniature excitatory postsynaptic currents. By buffering postsynaptic Ca2+ , it was shown that the decrease in "mini" frequency was due to an increase in postsynaptic Ca2+ .

Objectives Impaired arousal signifies underlying brain dysfunction, but its clinical significance outside the intensive care unit remains unclear. We sought to determine if impaired arousal at initial presentation was associated with higher 6-month mortality and if this relationship existed in the absence of delirium.

The size of the terrestrial carbon (C) sink is mediated by the availability of nutrients that limit plant growth. However, nutrient controls on primary productivity are poorly understood in the geographically extensive yet understudied tropical dry forest biome. To examine how nutrients influence above- and belowground biomass production in a secondary, seasonally dry tropical forest, we conducted a replicated, fully factorial nitrogen (N) and phosphorus (P) fertilization experiment at the stand scale in Guanacaste, Costa Rica. The production of leaves, wood, and fine roots was monitored through time; root colonization by mycorrhizal fungi and the abundance of N-fixing root nodules were also quantified. In this seasonal forest, interannual variation in rainfall had the largest influence on stand-level productivity, with lower biomass growth under drought. By contrast, aboveground productivity was generally not increased by nutrient addition, although fertilization enhanced growth of individual tree stems in a wet year. However, root growth increased markedly and consistently under P addition, significantly altering patterns of stand-level biomass allocation to above- vs. belowground compartments. Although nutrients did not stimulate total biomass production at the community scale, N-fixing legumes exhibited a twofold increase in woody growth in response to added P, accompanied by a dramatic increase in the abundance of root nodules. These data suggest that the relationship between nutrient availability and primary production in tropical dry forest is contingent on both water availability and plant functional diversity.

Evidence is emerging that neuronal nicotinic acetylcholine receptors (nAChRs) in the mesolimbic dopamine (DA) system are involved in mediating the reinforcing effects of alcohol. Midbrain DA neurons express high levels of α6 subunit-containing nAChRs that modulate DA transmission, implicating their involvement in reward-related behaviours. This study assessed the role of α6-containing nAChRs in modulating alcohol reward using transgenic mice expressing mutant, hypersensitive α6 nAChR subunits (α6L9′S mice). α6L9′S mice and littermate controls were tested in three well-established models of alcohol reward: 24-h two-bottle choice drinking, drinking in the dark (DID), and conditioned place preference (CPP). Confocal microscopy and patch-clamp electrophysiology were used to show the localization and function of hypersensitive α6 subunit-containing nAChRs. Results indicate that female α6L9′S mice showed significantly higher alcohol intake at low concentrations of alcohol (3% and 6%) in the two-bottle choice procedure. Both male and female α6L9′S mice drank significantly more in the DID procedure and displayed an alcohol-induced place preference using a low dose of alcohol (0.5 g/kg) that was ineffective in littermate controls. Confocal microscopy showed that α6 subunit-containing nAChRs are selectively expressed on ventral tegmental area (VTA) DAergic, but not GABAergic neurons. Patch-clamp electrophysiology showed that VTA DA neurons of α6L9′S mice are hypersensitive to ACh. Collectively, these results suggest that α6L9′S mice are more sensitive to the rewarding effects of alcohol, and suggest that VTA α6 subunit-containing nAChRs modulate alcohol reward. Thus, α6 subunit-containing nAChRs may be a promising therapeutic target for treatment of alcohol use disorders.

Although there are generalized conceptual models that predict how above and belowground biomass increase during secondary succession after abandonment from agriculture, there are few data to test these models for fine roots (defined as 2 mm diameter) in tropical forests. We measured live and dead fine roots (0–10 cm depth) in 18 plots of regenerating tropical dry forest in Costa Rica that varied in age from 5 to 60 yrs, as well as in soil properties. We predicted that both stand age and soil fertility would affect fine roots, with greater values in older forests on low fertility soils. Across two sampling dates and locations, live fine roots varied from 0.35 to 3.53 Mg/ha and dead roots varied from 0.15 to 0.93 Mg/ha. Surprisingly, there was little evidence that surface fine roots varied between sampling dates or in relation to stand age. By contrast, total, live, and dead fine roots averaged across sampling dates within plots were negatively correlated with a multivariate index of soil fertility (Pearson correlations coefficients were 0.64, 0.58, and 0.68, respectively; P < 0.01) and other individual edaphic variables including pH, silt, calcium, magnesium, nitrogen, and phosphorus. These results suggest that soil fertility is a more important determinant of fine roots than forest age in tropical dry forests in Costa Rica, and that one-way these plant communities respond to low soil fertility is by increasing fine roots. Thus, simple conceptual models of forest responses to abandonment from agriculture may not be appropriate for surface fine roots.

 Premise of the Study: Because legumes can add nitrogen (N) to ecosystems through symbiotic fi xation, they play important roles in many plant communities, such as prairies and grasslands. However, very little research has examined the effect of projected climate change on legume growth and function. Our goal was to study the effects of temperature on growth, nodulation, and N chemistry of prairie legumes and determine whether these effects are mediated by source of N.  Methods: We grew seedlings of Amorpha canescens , Dalea purpurea , Lespedeza capitata , and Lupinus perennis at 25/20 ° C (day/night) or 28/23 ° C with and without rhizobia and mineral N in controlled-environment growth chambers. Biomass, leaf area, nodule number and mass, and shoot N concentration and δ 15 N values were measured after 12 wk of growth.  Key Results: Both temperature and N-source affected responses in a species-specifi c manner. Lespedeza showed increased growth and higher shoot N content at 28 ° C. Lupinus showed decreases in nodulation and lower shoot N concentration at 28 ° C. The effect of temperature on shoot N concentration occurred only in individuals whose sole N source was N 2 -fi xation, but there was no effect of temperature on δ 15 N values in these plants.  Conclusions: Elevated temperature enhanced seedling growth of some species, while inhibiting nodulation in another. Temperature-induced shifts in legume composition or nitrogen dynamics may be another potential mechanism through which climate change affects unmanaged ecosystems.

Objective Our objective is to determine whether quetiapine was superior to placebo in increasing weight or reducing core symptoms of anorexia nervosa as assessed by the Yale–Brown–Cornell Eating Disorder Scale and the Eating Disorder Inventory-2. Method Participants were randomised to 8 weeks of quetiapine or placebo. Results There are 21 participants who signed informed consent, 15 were randomised, 14 returned for at least one visit after receiving drug and 10 completed the study. There were no differences between drug and placebo in questionnaire scores, weight or measures of anxiety or depression. Discussion There was no difference between quetiapine and placebo on weight gain or core symptoms. Small effect sizes suggest that a higher number of participants would not increase significant differences between groups. Copyright © 2012 John Wiley & Sons, Ltd and Eating Disorders Association.

Three experiments used the intragastric alcohol consumption (IGAC) procedure to examine the effects of variations in passive ethanol exposure on withdrawal and voluntary ethanol intake in two inbred mouse strains, C57BL/6J (B6) and DBA/2J (D2). Experimental treatments were selected to induce quantitative differences in ethanol dependence and withdrawal severity by: (1) varying the periodicity of passive ethanol exposure (three, six or nine infusions/day); (2) varying the dose per infusion (low, medium or high); and (3) varying the duration of passive exposure (3, 5 or 10 days). All experiments included control groups passively exposed to water. B6 mice generally self-infused more ethanol than D2 mice, but passive ethanol exposure increased IGAC in both strains, with D2 mice showing larger relative increases during the first few days of ethanol access. Bout data supported the characterization of B6 mice as sippers and D2 mice as gulpers. Three larger infusions per day produced a stronger effect on IGAC than six or nine smaller infusions, especially in D2 mice. Increased IGAC was strongly predicted by cumulative ethanol dose and intoxication during passive exposure in both strains. Withdrawal during the passive exposure phase was also a strong predictor of increased IGAC in D2 mice. However, B6 mice showed little withdrawal, precluding analysis of its potential role. Overall, these data support the hypothesis that dependence-induced increases in IGAC are jointly determined by two processes that might vary across genotypes: (1) tolerance to aversive postabsorptive ethanol effects and (2) negative reinforcement (i.e. alleviation of withdrawal by self-administered ethanol).

An increase in oxidative stress and decrease in antioxidant enzymes have been suggested to be involved in the pathophysiology of myocardial infarction (MI). In this study in rats, treadmill exercise training and losartan treatment began 1 week post-myocardial infarction (MI) and lasted 8 weeks. We evaluated the changes in the mRNA and protein expressions for the enzymatic antioxidants superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase after exercise and losartan treatment post-MI. Our results demonstrated that GPx and catalase mRNA levels were comparable among all the groups, while the mRNA level for manganese SOD (MnSOD) was significantly increased in exercise training with/without losartan treatment compared with the sedentary post-MI group. Moreover, the mRNA level for gp91(phox) was dramatically decreased by a combination of exercise and losartan treatment. The protein levels for MnSOD were significantly elevated by exercise training in combination with losartan treatment. The protein levels for catalase were significantly increased in response to exercise, and further augmented by exercise together with losartan treatment. Thiobarbituric acid-reactive substances in plasma were significantly increased in the post-MI rats, but were decreased by exercise or losartan treatment, indicating that both exercise and losartan may reduce lipid oxidative damage. In addition, catalase and SOD enzymatic activities were significantly enhanced by exercise combined with losartan treatment. Our results suggest that exercise training improves catalase and MnSOD expression and attenuates oxidative stress. These effects are potentiated when combining exercise with angiotensin II receptor blockade.

Summary 1. One way to simplify the high taxonomic diversity of plant species in vegetation models is to place species into groups based on shared, dominant traits. Many studies have suggested that morphological and physiological traits of tropical dry forest tree species vary with leaf habit (i.e. leaves from evergreen, deciduous or semi-deciduous species) and thus this characteristic may serve as a useful way to distinguish ecologically meaningful functional types. 2. In this study we examine whether 10 plant traits vary with leaf habit in replicated leaves and individual trees of 87 species from a tropical dry forest in Costa Rica. We also looked for evidence of phylogenetic conservatism, i.e. closely related species sharing similar trait values compared to more distantly related taxa. 3. While some of the traits varied within and among individual trees of the same species, interspecific variation accounted for 57–83% of the variance among samples. Four traits in addition to leaf habit showed evidence of phylogenetic conservatism, but these results were strongly dependent on the inclusion of the 18 species of legumes (Fabaceae) in our dataset. Contrary to our predictions, none of the traits we measured differed among leaf habits. However, five traits (wood density, leaf C, leaf N, N ⁄ P and C ⁄ N) varied significantly between legumes and other functional types. Furthermore, when all high-nitrogen non-legume taxa were compared to the high-nitrogen legumes, six traits excluding leaf N differed significantly, indicating that legumes are functionally different from other tree species beyond high N concentrations. Similarly, the 18 legume taxa (which all have compound leaves) also differed from other compound-leaved species for six traits, thus leaf type does not explain these patterns. 4. Our main conclusions are that (i) a plant functional type classification based on leaf habit alone has little utility in the tropical dry forest we studied, and (ii) legumes have a different suite of traits including high leaf carbon and wood density in addition to high leaf nitrogen. Whether this result generalizes to other tropical forests is unknown, but merits future research due to the consequences of these traits for carbon storage and ecosystem processes.

Extracellular enzymes are the proximate agents of organic matter decomposition and measures of these activities can be used as indicators of microbial nutrient demand. We conducted a global-scale meta-analysis of the seven-most widely measured soil enzyme activities, using data from 40 ecosystems. The activities of b-1,4-glucosidase, cellobiohydrolase, b-1,4-N-acetylglucosaminidase and phosphatase g )1 soil increased with organic matter concentration; leucine aminopeptidase, phenol oxidase and peroxidase activities showed no relationship. All activities were significantly related to soil pH. Specific activities, i.e. activity g )1 soil organic matter, also varied in relation to soil pH for all enzymes. Relationships with mean annual temperature (MAT) and precipitation (MAP) were generally weak. For hydrolases, ratios of specific C, N and P acquisition activities converged on 1 : 1 : 1 but across ecosystems, the ratio of C : P acquisition was inversely related to MAP and MAT while the ratio of C : N acquisition increased with MAP. Oxidative activities were more variable than hydrolytic activities and increased with soil pH. Our analyses indicate that the enzymatic potential for hydrolyzing the labile components of soil organic matter is tied to substrate availability, soil pH and the stoichiometry of microbial nutrient demand. The enzymatic potential for oxidizing the recalcitrant fractions of soil organic material, which is a proximate control on soil organic matter accumulation, is most strongly related to soil pH. These trends provide insight into the biogeochemical processes that create global patterns in ecological stoichiometry and organic matter storage.

Summary 1 Social species in the spider genus Anelosimus predominate in lowland tropical rainforests, while congeneric subsocial species occur at higher elevations or higher latitudes. 2 We conducted a comparative study to determine whether differences in total biomass, insect size or both have been responsible for this pattern. 3 We found that larger average insect size, rather than greater overall biomass per se, is a key characteristic of lowland tropical habitats correlating with greater sociality. 4 Social species occupied environments with insects several times larger than the spiders, while subsocial species nearing dispersal occupied environments with smaller insects in either high or low overall biomass. 5 Similarly, in subsocial spider colonies, individuals lived communally at a time when they were younger and therefore smaller than the average insect landing on their webs. 6 We thus suggest that the availability of large insects may be a critical factor restricting social species to their lowland tropical habitats.

Objective: This article examined possible ways of classifying eating disorders not otherwise specified (EDNOS) using latent profile analysis (LPA). Method: Of 687 patients being seen for an evaluation for an eating disorder, 284 were classified as having anorexia nervosa (AN) or bulimia nervosa (BN). LPA was performed on the remaining 403 cases (EDNOS). Results: Five clusters were identified that characterized individuals who appeared to be: (1) subsyndromal restrictor AN patients that denied a great deal of eating disorder (ED) psychopathology; (2) subsyndromal ED patients, some but not all of whom were low weight; (3) subsyndromal BN with higher rates of vomiting than binge-eating; (4) primarily overweight individuals with low levels of ED pathology; or (5) overweight patients who most resembled binge eating disorder (BED). Conclusion: Most EDNOS cases resembled AN, BN, or BED cases and can be conceptualized several ways, one of which is to see them as existing on a continuum with the DSM-IV ED. Int J Eat Disord 2007 © 2007 by Wiley Periodicals, Inc.