Interação comportamento de pastejo<FONT FACE=Symbol>&acute;</FONT>dinâmica de tipos funcionais em pastagem natural na depressão central do Rio Grande do Sul Interaction between grazing behavior and functional type dynamics in native grassland in the central depression Region of Rio Grande do Sul

Este estudo foi realizado com o objetivo de avaliar os comportamentos alimentar e espacial de bovinos em pastejo em função da dinâmica de tipos funcionais (TF) em pastagem natural, definidos por meio da descrição de atributos morfológicos. Foram utilizadas novilhas em pastejo rotacionado, com oferta média de forragem de 12% (12 kg de MS/100 kg PV). O ritmo de atividade dos animais foi acompanhado durante o período de 12/02 a 27/02/2003 utilizando-se registradores automáticos Ethosys. Para a medição dos atributos, foram marcadas 30 unidades amostrais permanentes, compostas de cinco quadros contíguos de 0,20 x 0,20 m. Os resultados da descrição da comunidade indicaram um subconjunto ótimo de dois atributos (biomassa superior e biomassa lenhosa), os quais definiram oito TF, indicando congruência de 0,43 com a variável ambiental graus-dia. A evolução dos tempos de pastejo comprovou que, à medida que diminuem os TF preferidos, ocorre aumento nos tempos de pastejo. A caracterização da vegetação com base na definição de atributos, em comparação àquela realizada somente pela identificação das espécies presentes na área, facilitou a compreensão da resposta interativa vegetação &acute; animal. Simultaneamente, à medida que a vegetação se alterou, os animais modularam seu comportamento ajustando seus ritmos de atividade, no tempo e no espaço, provocando continuamente impactos diferenciais na vegetação, que evolui com o tempo.This study aimed to describe the feeding and spatial behavior of beef heifers under rotational stocking, in response to the dynamics of the morphological functional types (TFs) in natural grassland. Stocking rate was adjusted to keep an average of 12% (12 kg DM/100 kg BW) of forage allowance. Animal activity was registered from 12 to 27 February 2003 using the Ethosys automatic device. Thirty permanent field sampling units comprised by five adjacent 0.20 x 0.20 m squares were used to determine pasture attributes. Results showed the existence of an optimum subset of two attributes to describe pasture plant community: the aerial and the lignified (woody) forage biomasses, which defined eight morphological functional types that had a 0.43 congruency value with the variable degree-day. The evolution of grazing activity showed that grazing time increased as the frequency of preferred functional types decreased. Thus, the morphological characterization of functional type-based attribute definition can bring more contributions for the interactive response between the vegetation and the animal behavior than the one realized using only the taxonomic identification. Therefore, in a simultaneous action, as the vegetation change, the animals modulate the behavior adjusting their rhythm of activity in time and space, determining, in a continuous process, differential impacts in the vegetation, which evolves with time

Global relationships in tree functional traits

Due to massive energetic investments in woody support structures, trees are subject to unique physiological, mechanical, and ecological pressures not experienced by herbaceous plants. Despite a wealth of studies exploring trait relationships across the entire plant kingdom, the dominant traits underpinning these unique aspects of tree form and function remain unclear. Here, by considering 18 functional traits, encompassing leaf, seed, bark, wood, crown, and root characteristics, we quantify the multidimensional relationships in tree trait expression. We find that nearly half of trait variation is captured by two axes: one reflecting leaf economics, the other reflecting tree size and competition for light. Yet these orthogonal axes reveal strong environmental convergence, exhibiting correlated responses to temperature, moisture, and elevation. By subsequently exploring multidimensional trait relationships, we show that the full dimensionality of trait space is captured by eight distinct clusters, each reflecting a unique aspect of tree form and function. Collectively, this work identifies a core set of traits needed to quantify global patterns in functional biodiversity, and it contributes to our fundamental understanding of the functioning of forests worldwide.Understanding patterns in woody plant trait relationships and trade-offs is challenging. Here, by applying machine learning and data imputation methods to a global database of georeferenced trait measurements, the authors unravel key relationships in tree functional traits at the global scale

Climatic and soil factors explain the two-dimensional spectrum of global plant trait variation

Plant functional traits can predict community assembly and ecosystem functioning and are thus widely used in global models of vegetation dynamics and land–climate feedbacks. Still, we lack a global understanding of how land and climate affect plant traits. A previous global analysis of six traits observed two main axes of variation: (1) size variation at the organ and plant level and (2) leaf economics balancing leaf persistence against plant growth potential. The orthogonality of these two axes suggests they are differently influenced by environmental drivers. We find that these axes persist in a global dataset of 17 traits across more than 20,000 species. We find a dominant joint effect of climate and soil on trait variation. Additional independent climate effects are also observed across most traits, whereas independent soil effects are almost exclusively observed for economics traits. Variation in size traits correlates well with a latitudinal gradient related to water or energy limitation. In contrast, variation in economics traits is better explained by interactions of climate with soil fertility. These findings have the potential to improve our understanding of biodiversity patterns and our predictions of climate change impacts on biogeochemical cycles

Climatic and soil factors explain the two-dimensional spectrum of global plant trait variation

Plant functional traits can predict community assembly and ecosystem functioning and are thus widely used in global models of vegetation dynamics and land-climate feedbacks. Still, we lack a global understanding of how land and climate affect plant traits. A previous global analysis of six traits observed two main axes of variation: (1) size variation at the organ and plant level and (2) leaf economics balancing leaf persistence against plant growth potential. The orthogonality of these two axes suggests they are differently influenced by environmental drivers. We find that these axes persist in a global dataset of 17 traits across more than 20,000 species. We find a dominant joint effect of climate and soil on trait variation. Additional independent climate effects are also observed across most traits, whereas independent soil effects are almost exclusively observed for economics traits. Variation in size traits correlates well with a latitudinal gradient related to water or energy limitation. In contrast, variation in economics traits is better explained by interactions of climate with soil fertility. These findings have the potential to improve our understanding of biodiversity patterns and our predictions of climate change impacts on biogeochemical cycles. The authors investigate the broad-scale climatological and soil properties that co-vary with major axes of plant functional traits. They find that variation in plant size is attributed to latitudinal gradients in water or energy limitation, while variation in leaf economics traits is attributed to both climate and soil fertility including their interaction

High exposure of global tree diversity to human pressure

Safeguarding Earth’s tree diversity is a conservation priority due to the importance of trees, for biodiversity and ecosystem functions and services such as carbon sequestration. Here,, we improve the foundation for effective conservation of global tree diversity by analyzing, a recently developed database of tree species covering 46,752 species. We quantify range, protection and anthropogenic pressures for each species and develop conservation priorities, across taxonomic, phylogenetic, and functional diversity dimensions. We also assess, the effectiveness of several influential proposed conservation prioritization frameworks to, protect the top 17% and top 50% of tree priority areas. We find that an average of, 50.2% of a tree species’ range occurs in 110-km grid cells without any protected areas, (PAs), with 6,377 small-range tree species fully unprotected, and that 83% of tree species, experience nonnegligible human pressure across their range on average. Protecting high priority, areas for the top 17% and 50% priority thresholds would increase the average, protected proportion of each tree species’ range to 65.5% and 82.6%, respectively, leaving, many fewer species (2,151 and 2,010) completely unprotected. The priority areas, identified for trees match well to the Global 200 Ecoregions framework, revealing that, priority areas for trees would in large part also optimize protection for terrestrial biodiversity, overall. Based on range estimates for &gt;46,000 tree species, our findings show that a, large proportion of tree species receive limited protection by current PAs and are under, substantial human pressure. Improved protection of biodiversity overall would also, strongly benefit global tree diversity

Global beta-diversity of angiosperm trees is shaped by Quaternary climate change

As Earth's climate has varied strongly through geological time, studying the impacts of past climate change on biodiversity helps to understand the risks from future climate change. However, it remains unclear how paleoclimate shapes spatial variation in biodiversity. Here, we assessed the influence of Quaternary climate change on spatial dissimilarity in taxonomic, phylogenetic, and functional composition among neighboring 200-kilometer cells (beta-diversity) for angiosperm trees worldwide. We found that larger glacial-interglacial temperature change was strongly associated with lower spatial turnover (species replacements) and higher nestedness (richness changes) components of beta-diversity across all three biodiversity facets. Moreover, phylogenetic and functional turnover was lower and nestedness higher than random expectations based on taxonomic beta-diversity in regions that experienced large temperature change, reflecting phylogenetically and functionally selective processes in species replacement, extinction, and colonization during glacial-interglacial oscillations. Our results suggest that future human-driven climate change could cause local homogenization and reduction in taxonomic, phylogenetic, and functional diversity of angiosperm trees worldwide