Fertilização em Eucalyptus dunnii Maiden no bioma Pampa - Brasil

In silviculture, mineral fertilization is necessary to supply the nutritional demand, however, the recommendation of the quantities to be applied should aim at maintaining the productive capacity of the soil. The purpose of this study is to test whether increasing the recommended fertilizer dose improves soil fertility and increases the productivity of Eucalyptus dunnii in sites in the central region of the Pampa biome, Brazil. The doses of 150 g (T0), 225 g (T1) and 450 g (T2) of N-P2O5-K2O were applied 24:00:24 per plant, after 14 months of planting. In all tested doses, the species productivity is considered satisfactory for the site. There was an improvement in soil fertility, especially in potassium contents, in addition to a higher individual volume of Eucalyptus dunnii trees after the application of the dose of 450 g plant-1 of N-P2O5-K2O, 24:00:24 in coverage (T2).

Universality in biodiversity patterns: Variation in species-temperature and species-productivity relationships reveals a prominent role of productivity in diversity gradients

Temperature and productivity appear as universal positive correlates of species richness. However, the strength and the shape of species-temperature (STR) and species-productivity (SPR) relationships vary widely, and the causes of this variation are poorly known. We analysed (1) published species richness data for multiple taxa sampled in various regions and (2) different clades within vertebrate classes globally, to test for the effects of spatial scale and characteristics of examined taxa and regions on the strength and direction of STRs and SPRs. There are striking differences in the variation of the relationships among types of data, between ectotherms and endotherms and also between STRs and SPRs. Some sources of this variation are of statistical nature (e.g. the relationships are stronger if the range of temperature or productivity variation is wider), but non-statistical sources are more important and illuminate the processes responsible for the origin of biodiversity patterns. The SPRs are generally stronger and less variable than STRs, and SPR variation is weakly related to the explored factors - the SPRs are stronger in warmer regions in ectotherms, while clade size is the only factor consistently affecting the strength of the SPR in endotherms. In contrast, STRs are weaker and more variable, and this variation is linked to region characteristics - most importantly, STRs are stronger in the regions where temperature positively correlates with productivity, indicating that productivity plays a role even in the STRs. The effect of temperature on species richness is thus complex and context-dependent, while productivity is a more universal driver of species richness patterns, largely independent of particular characteristics of given region or taxon. Productivity thus appears as the main proximate driver of species richness patterns, probably due to its effect on the limits of the number of viable populations which can coexist in a given environment.

Risk-based evaluation of the vulnerability of the Skagerrak–Kattegat marine fish community to Swedish fisheries

Progress towards ecosystem-based fisheries management calls for useful tools to prioritize actions. To select suitable methods for local circumstances, evaluating approaches used in other jurisdictions can be a cost-effective first step. We tested Productivity Susceptibility Analysis (PSA) to assess the potential vulnerability of the marine fish community in the Skagerrak–Kattegat (Eastern North Sea) to possible interactions with all Swedish fisheries operating in the area. This analysis combines attributes for a species productivity with attributes related to the susceptibility to capture to quantify a single score for vulnerability: high, medium, or low risk. Results indicate that demersal trawl and gillnet fisheries were associated with the highest risk levels if interaction occurs, i.e. having the highest prevalence of species with potentially high vulnerability to the fisheries. Mixed results were seen when comparing the assessment results with available data. The main benefit of utilizing PSA in the area is the comprehensiveness of the assessment, including data-deficient fisheries and species. Drawbacks include potential overestimation of actual risks. Overall, together with available data, PSA in the studied area provides a comprehensive map of potential risks for further actions and may progress a science-based, precautionary management of the area.

Endophytic fungus diversity in soybean plants submitted to conditions of elevated atmospheric CO2 and temperature

Global climatic changes can have drastic impacts on plant species including severe consequences for the agricultural species productivity. Many of these species present important mutualisms with endophytic fungi that positively influence their performance. The present study evaluated whether the increases in CO₂ and temperature predicted for the year 2100 may cause changes in foliar carbon (C) and nitrogen (N) concentrations in soybean (<i>Glycine max</i>) and, consequently, the interactions with its endophytic fungi. The effects of elevated CO₂ and temperature were evaluated in four treatments in open-top chambers: (1) Control; (2) Increased Temperature; (3) Increased CO₂; (4) Increased CO₂ and Temperature. Increased atmospheric CO₂ resulted in decreased foliar nitrogen concentration, while increased temperature increased it. A total of 16 taxa of endophytic fungi were identified based on sequencing <i><i>ITS</i></i> (Internal Transcribed Spacer) regions of rRNA subunits. Increased atmospheric CO₂ and temperature were observed to potentially modify the endophytic mycobiota of soybean plants. Results suggest the fungi species substitution as a consequence of changes in foliar nitrogen concentration and C:N ratio. Predicted climatic changes shall affect the plant and endophytes relationships, which will in turn affect the performance and resistance of soybean, one of the most important crops in the world.

Species Ecological Envelopes under Climate Change Scenarios: A Case Study for the Main Two Wood-Production Forest Species in Portugal

Species ecological envelope maps were obtained for the two main Portuguese wood-production species (Eucalyptus globulus Labill. and Pinus pinaster Aiton) and projected future climate change scenarios. A machine learning approach was used to understand the most influential environmental variables that may explain current species distribution and productivity. Background and Objectives: The aims of the study were: (1) to map species potential suitability areas using ecological envelopes in the present and to project them in the future under climate change scenarios; (2) to map species current distributions; (3) to map species current productivity; and (4) to explore the most influential environmental variables on species current distribution and productivity. Materials and Methods: Climate, elevation data, and soil data sets were used to obtain present and future species ecological envelopes under two climate change scenarios. The official land cover maps were used to map species distributions. Forest inventory data were used to map the species productivity by geostatistical techniques. A Bayesian machine learning approach, supported by species distributions and productivity data, was used to explore the most influential environmental variables on species distribution and productivity and to validate species ecological envelopes. Results: The species ecological envelope methodology was found to be robust. Species’ ecological envelopes showed a high potential for both species’ afforestation. In the future, a decrease in the country’s area potentiality was forecasted for both species. The distribution of maritime pine was found to be mainly determined by precipitation-related variables, but the elevation and temperature-related variables were very important to differentiate species productivity. For eucalypts, species distribution was mainly explained by temperature-related variables, as well as the species productivity. Conclusions: These findings are key to support recommendations for future afforestation and will bring value to policy-makers and environmental authorities in policy formulation under climate change scenarios.

Modeling How Community Assembly Alters the Functioning of Ecosystems

Although the effects of species richness on ecosystem functioning have been extensively studied, there is increased interest in understanding how community assembly in a more general sense can alter the functioning of ecosystems. We identify two complementary approaches for evaluating how community assembly influences biomass production. The first quantifies the relative importance of complementarity and selection by contrasting monocultures with polycultures. The second identifies the effects of species replacements (losses and/or gains of species relative to the baseline polyculture) as well as the indirect effects on other species’ productivity. We compare and contrast these two approaches using simulated communities where species compete for different resource types and experience different levels of environmental heterogeneity and find that these metrics can jointly diagnose the mechanisms of competition driving productivity. We apply our methods to data from a long-term biodiversity-ecosystem experiment (the Jena Experiment) and find that the data do not correspond to any of the competition scenarios we modeled. We address two additional possible complications: facilitation by nitrogen fixing plants, and non-equilibrium behavior during community assembly, and find that facilitation/competition by nitrogen fixing plants is the more likely explanation for the results obtained at Jena.

Evaluating habitat-fishery interactions: Submerged aquatic vegetation and blue crab fishery in the Chesapeake Bay

This paper investigates habitat-fisheries interaction between two important resources in the Chesapeake Bay: blue crabs and submerged aquatic vegetation (SAV). A habitat can be essential to a species (the species is driven to extinction without it), facultative (more habitat means more of the species, but species can exist at some level without any of the habitat) or irrelevant (more habitat is not associated with more of the species). An empirical bioeconomic model that allows for all three possible relationships was estimated and two alternative approaches were used to test whether SAV matters for the crab stock. Our results indicate that a model that incorrectly assumes that habitat is essential to a species can result in model misspecification and biased estimates of the impact of habitat on species productivity. Using a model that assumes an essential relationship, we find that SAV has a significant positive impact on blue crab productivity (p<0.001). However, in a more general model, we failed to reject the null hypothesis that SAV is irrelevant for crabs in the Bay (p>0.05).