Austral Ecology最新文献

Understanding how plant functional traits reflect adaptations to different environmental contexts is crucial for predicting vegetation responses to selection pressures imposed by environmental filters. This study examines the functional strategies of woody plants in riparian forests along the Rio Doce, Brazil, particularly focusing on how these strategies vary between saplings and mature trees in response to soil condition, temperature and precipitation. Using Grime's CSR (Competitor, Stress-tolerant, Ruderal) model, we analysed functional traits and their relationship with environmental parameters across 15 reference riparian sites spanning 473 km of the river. We found a large variation in species functional traits and ecological strategies in both strata, with significant inter-site differences reflecting regional environmental gradients. Based on community weighted mean values, there were clear differences in ecological strategies displayed by the multiple riparian forests found along the Rio Doce watershed in both strata. Trait-environment relationship analyses highlighted how trait syndromes shift with environmental gradients. In general, we found for both strata a clear association between climatic variables and species functional traits, with higher C-selection and leaf size positively related to higher precipitation and lower temperature. On the other hand, edaphic characteristics related differently to species' functional dimensions in each stratum. Soil chemical quality was fundamental for the tree stratum, reflecting the access of deeper root systems to nutrients in lower soil horizons, while soil texture was the main filter for the juvenile stratum, as it directly regulates the availability of water and oxygen for its more superficial roots. By linking functional traits and ecological strategies to environmental factors, our findings indicate that restoration initiatives in the Doce River watershed should abandon the one-size-fits-all approach. Instead, they require the implementation of multiple region-specific reference ecosystems, according to different ecological strategies shaped by different climatic and edaphic filters along the river.

Whether the diversity and composition of animal communities are determined by vegetation structure or composition has been an ongoing debate. However, due to combined shortcomings of data and methodology, vegetation structure has been prioritised when trying to understand the effects of vegetation upon animal communities. Here, we explored the relative importance of vegetation structure and woody plant species composition on the prediction of small mammal assemblages for an Atlantic Forest landscape. Compositional (small mammals and woody plants) and vegetation structural data were collected in 20 forest sites in the Guapi-Macacu river basin, Rio de Janeiro, Brazil. We used direct ordination techniques (co-correspondence and predictive canonical correspondence analysis) to compare the predictive capacities of vegetation structure and woody plant species composition on small mammal composition. Woody plant species composition explained more variation in small mammal composition than vegetation structure, but more importantly, woody plant species composition and vegetation structure explained different parts of the variation in small mammal composition. Therefore, vegetation structure and woody plant species composition, besides being closely linked, have complementary roles for small mammal assemblages. Among the plant species, Senefeldera verticillata, Myrcia multiflora and Guarea guidonia had the strongest influence on predictive power. Identifying such species is relevant not only statistically, but also for guiding conservation and restoration strategies that aim to sustain small mammal assemblages. We demonstrate that disentangling the role of woody plant species composition on animal community composition might be a complex task; nevertheless, it is a fundamental one to accurately understand the structure, and composition, of animal assemblages.

Given the importance of soil conditions for ecosystem functioning, fertilisation experiments are a valuable tool for assessing how systems respond to changes in soil properties. However, the effects of changes in nutrient availability on multitrophic interactions in savannah ecosystems of the Brazilian Cerrado are still scarce. We investigated the long-term effects of soil nutrient addition (N, P, NP, and liming (Ca)) on the leaf metabolomics of the tree Blepharocalyx salicifolius (Kunth) O. Berg (Myrtaceae), changes in herbivory rates, and the spore density of arbuscular mycorrhizal fungi in the rhizosphere. Metabolomic analysis of the leaves indicated a differentiation between B. salicifolius in control plots and the other treatments, with the most pronounced changes observed in response to Ca treatment. The abundance of mycorrhizal spores and leaf damage was higher in the Ca treatment than in the control. Our results show that changes in soil pH and nutrient availability can influence plant physiology and community processes, with significant consequences for ecosystem interactions. We highlight the importance of a broader understanding of how tropical trees respond to nutrient availability changes and the resulting implications for ecosystem functioning.

Functional traits mediate resource acquisition and environmental tolerance, influencing community structure and ecosystem functioning. Here, we assessed the correlation between climatic factors and altitude with the spatial distribution of tree functional traits in the Subtropical Atlantic Forest (SAF). We compiled the information on tree communities in 83 inventories, assessing functional traits (spinescence, extrafloral nectaries (EFN), wood density, symbiotic fixation of nitrogen (SFN), deciduousness, leaf area, leaf border and leaf apex types) of 859 species and calculated the community-weighted mean (CWM) trait values. We used the RLQ multivariate and fourth-corner methods to relate the CWM to the climate variables and altitude. Deciduousness, SFN, leaves with toothed/serrated (not smooth) border, spinescence and leaf area were more significantly associated with climatic drivers. Spinescence and toothed leaf border were positively associated with colder and rainier regions. In turn, the occurrence of EFN increases with temperature seasonality. Deciduousness and SFN were mainly associated with higher diurnal and annual temperature ranges and isothermality. SFN is also correlated with precipitation seasonality. Larger leaf area values are associated with more favourable climates for carbon acquisition, that is, without extreme colder temperatures and lower temperature variation. The association between leaf deciduousness and SFN with daily and annual temperature variation may help to cope with abiotic conditions unfavourable to photosynthesis. In turn, to the extent that it is associated with hydathodes, toothed leaves are possibly important in hydric equilibria in cold and humid conditions. However, the association of spinescence with cold and rainy climates was unexpected. In the absence of severe aridity, the coldest climates are possibly the most limiting for primary productivity in the SAF, favouring conservative traits such as spines. The results suggest that the expression of traits in forest communities in southern Brazil is driven by climate, especially temperature variables, which may imply differences in ecosystem functioning in the region.

Native temperate grasslands are among the most widespread biomes in Australia, and they have been extensively modified, primarily for livestock grazing and cropping on the fertile soils ideal for agriculture. In the 1980s and 1990s, foundational work by Jamie Kirkpatrick and others brought attention to the widespread loss of these ecosystems, inspiring four decades of ecological research and conservation efforts. This review synthesises the current state of native temperate grasslands in south-eastern Australia, examining trends in their ecology, protection, management and restoration. Despite progress, grassland loss and degradation continue, with many remnants experiencing declining condition and ongoing local extinctions, even within conservation reserves. A major driver is the disruption of ecological processes, particularly fire and grazing, leading to biotic homogenisation. While habitat protection remains important, it is no longer sufficient. We highlight the urgent need for population augmentation programmes and the restoration—or reimagining—of key ecological processes that sustain grassland biodiversity. As species losses and invasions re-shape these ecosystems, a new generation of researchers and practitioners must build on the legacies of Kirkpatrick and others to develop adaptive, forward-looking conservation strategies. We identify critical priorities to inform future policy and land management aimed at securing the persistence of native temperate grassland communities in a changing world.

Climate change presents significant challenges to species survival; however, the long-term effects on tropical lizard populations remain poorly understood. Previous studies have predicted contrasting outcomes, with some forecasting a high risk of extinction due to rising temperatures, while others suggest greater resilience in tropical habitats. To address this gap, we analysed the population dynamics of G. humeralis at two time points, spaced 20 years apart, in Central-Eastern Amazonia, focusing on how temperature increases and habitat quality affect population growth rates. We surveyed G. humeralis across 24 sampling plots, each with 1000 m of trails, in 2001 and 2021, to assess the impact of high temperatures (restriction hours), forest area, isolation from continuous forest, differences in invertebrate biomass and differences in forest cover between 2021 and 2001 on G. humeralis population growth rates using Generalised Linear Mixed Models (GLMM). Our findings indicate that the G. humeralis population increased significantly, with 192 individuals recorded in 2001 and 452 in 2021, demonstrating resilience to increases in temperature during that period. While growth rates were slightly impacted by higher temperatures, the overall population did not decline, contradicting previous extinction predictions due to climate change. Moreover, the analysed environmental variables did not significantly affect the species' population growth rates. Our data clearly indicate that G. humeralis is resilient to long-term habitat fragmentation and that the predictions of previous models are not supported by our findings, suggesting that the extinction of the species before 2070 may be less likely than previously proposed.