DIMENSÕES E PERSPECTIVAS DO SEGURO RURAL: O CASO BRASILEIRO E ALGUMAS EXPERIÊNCIAS INTERNACIONAIS

O seguro rural é um dos mais importantes instrumentos para o desenvolvimento do setor agrícola, pois, ao permitir proteção ao produtor rural contra efeitos adversos de eventos ambientais e do mercado torna-se indispensável à estabilidade da renda, à geração de emprego e ao desenvolvimento tecnológico. No setor agrícola, além do risco de mercado, existem diversas outras fontes que a tornam uma atividade eminentemente arriscada. A principal delas se refere ao fato de que a atividade agrícola é altamente dependente de condições ambientais de difícil controle pelo homem de modo que as variáveis climáticas e sua interação com fatores bióticos podem influenciar sobremaneira o resultado final da safra. A realidade histórica mostra que o seguro agrícola permite ao produtor rural manter sua renda na ocorrência de um sinistro, o que é fundamental para o do setor agrícola e a sociedade em geral. Contudo, o mercado de seguro agrícola brasileiro é insipiente e demandando reestruturação com intensa participação do setor privado e coordenado pelo do setor público.------------------------------------------------------Highly instrumental in the development of the agricultural sector insofar as it protects farmers from adverse weather and market conditions, agricultural insurance also plays a crucial role not only in income and employment generation, but also in technological advancements. Besides market risks, the agricultural sector is confronted with a wide spectrum of other risks, which makes agriculture an eminently risky enterprise. Chief among these risks is the high dependence of the agricultural activity on hard to control weather-driven events, so that natural environmental variability and its interaction with biotic factors can greatly affect crop yields. The historical reality shows that agricultural insurance allows that rural producer maintain the income level in the occurrence of a casualty, which is important to the agricultural sector and the society. However, the Brazilian agricultural insurance market is at a generally incipient stage and in urgent need of a restructuring involving intense participation of the private sector and coordination by the public sector.seguro rural, risco agrícola, política agrícola, agro-insurance, agricultural risk, agricultural policy, Risk and Uncertainty,

SEGURO RURAL NO BRASIL: EXPERIÊNCIAS E PROPOSIÇÕES PARA UM MODELO INTEGRADO DE GESTÃO DO RISCO AGRÍCOLA (MIGRA)

O seguro rural apresenta-se com um instrumento para o desenvolvimento do setor agrícola, protegendo o produtor rural dos efeitos adversos de eventos ambientais e do mercado tornando-se indispensável à estabilidade da renda, à geração de emprego e ao desenvolvimento tecnológico. Nesse sentido, sugere-se a consideração de um conjunto de indicadores que podem influir positivamente no processo de mitigação dos riscos inerentes ao seguro rural agrícola. Dessa forma, propõe-se o desenvolvimento de um Modelo Integrado de Gestão do Risco Agrícola para o Brasil (MIGRA) para o Brasil, um país que, além da heterogeneidade setorial, tem sua economia fortemente calcada no setor agrícola, o qual também é bastante heterogêneo quanto à produção e a renda agrícola. Esse modelo deve enfatizar a mitigação do risco no setor com base em um sistema de informação disponível para todos os segmentos do setor agrícola. A ênfase do MIGRA deve ser na redução da informação imperfeita e da assimetria de informação. Ainda, o MIGRA deverá considerar a diversidade dos sistemas de produção existentes no território nacional, notadamente quanto ao tamanho (pequeno e grande produtor segundo o capital) e o modo de exploração (agricultura patronal, empresarial ou não, e agricultura familiar).----------------------------------------------Highly instrumental in the development of the agricultural sector insofar as it protects farmers from adverse weather and market conditions, agricultural insurance also plays a crucial role not only in income and employment generation, but also in technological advancements. In this way, suggests the consideration of a group of indicators to agro-insurance. Thus this work proposes the development of an Integrated Agricultural Risk Management Model for Brazil (MIGRA), a country which, in addition to its sectorial heterogeneity, has its economy strongly based on an also heterogeneous the agricultural sector, concerning production types and agricultural income levels. Such model should emphasize risk mitigation in the sector through an information system available to all segments of the agricultural sector. The major focus of the MIGRA must be on the reduction of imperfect information and information asymmetry. Also, the MIGRA shall take into consideration the diversity of production systems extant in the national territory, notably with regards to the size (small and large producers according to capital intensity) and means of exploration (employer agriculture, entrepreneurial or not, and family agriculture).renda agrícola, risco agrícola, previsão de safras, agricultural income, agricultural risk, crop forecast, Risk and Uncertainty,

Evenness mediates the global relationship between forest productivity and richness

1. Biodiversity is an important component of natural ecosystems, with higher species richness often correlating with an increase in ecosystem productivity. Yet, this relationship varies substantially across environments, typically becoming less pronounced at high levels of species richness. However, species richness alone cannot reflect all important properties of a community, including community evenness, which may mediate the relationship between biodiversity and productivity. If the evenness of a community correlates negatively with richness across forests globally, then a greater number of species may not always increase overall diversity and productivity of the system. Theoretical work and local empirical studies have shown that the effect of evenness on ecosystem functioning may be especially strong at high richness levels, yet the consistency of this remains untested at a global scale. 2. Here, we used a dataset of forests from across the globe, which includes composition, biomass accumulation and net primary productivity, to explore whether productivity correlates with community evenness and richness in a way that evenness appears to buffer the effect of richness. Specifically, we evaluated whether low levels of evenness in speciose communities correlate with the attenuation of the richness–productivity relationship. 3. We found that tree species richness and evenness are negatively correlated across forests globally, with highly speciose forests typically comprising a few dominant and many rare species. Furthermore, we found that the correlation between diversity and productivity changes with evenness: at low richness, uneven communities are more productive, while at high richness, even communities are more productive. 4. Synthesis. Collectively, these results demonstrate that evenness is an integral component of the relationship between biodiversity and productivity, and that the attenuating effect of richness on forest productivity might be partly explained by low evenness in speciose communities. Productivity generally increases with species richness, until reduced evenness limits the overall increases in community diversity. Our research suggests that evenness is a fundamental component of biodiversity–ecosystem function relationships, and is of critical importance for guiding conservation and sustainable ecosystem management decisions

Native diversity buffers against severity of non-native tree invasions

Determining the drivers of non-native plant invasions is critical for managing native ecosystems and limiting the spread of invasive species$^{1,2}$. Tree invasions in particular have been relatively overlooked, even though they have the potential to transform ecosystems and economies$^{3,4}$. Here, leveraging global tree databases$^{5,6,7}$, we explore how the phylogenetic and functional diversity of native tree communities, human pressure and the environment influence the establishment of non-native tree species and the subsequent invasion severity. We find that anthropogenic factors are key to predicting whether a location is invaded, but that invasion severity is underpinned by native diversity, with higher diversity predicting lower invasion severity. Temperature and precipitation emerge as strong predictors of invasion strategy, with non-native species invading successfully when they are similar to the native community in cold or dry extremes. Yet, despite the influence of these ecological forces in determining invasion strategy, we find evidence that these patterns can be obscured by human activity, with lower ecological signal in areas with higher proximity to shipping ports. Our global perspective of non-native tree invasion highlights that human drivers influence non-native tree presence, and that native phylogenetic and functional diversity have a critical role in the establishment and spread of subsequent invasions

The global biogeography of tree leaf form and habit

Understanding what controls global leaf type variation in trees is crucial for comprehending their role in terrestrial ecosystems, including carbon, water and nutrient dynamics. Yet our understanding of the factors influencing forest leaf types remains incomplete, leaving us uncertain about the global proportions of needle-leaved, broadleaved, evergreen and deciduous trees. To address these gaps, we conducted a global, ground-sourced assessment of forest leaf-type variation by integrating forest inventory data with comprehensive leaf form (broadleaf vs needle-leaf) and habit (evergreen vs deciduous) records. We found that global variation in leaf habit is primarily driven by isothermality and soil characteristics, while leaf form is predominantly driven by temperature. Given these relationships, we estimate that 38% of global tree individuals are needle-leaved evergreen, 29% are broadleaved evergreen, 27% are broadleaved deciduous and 5% are needle-leaved deciduous. The aboveground biomass distribution among these tree types is approximately 21% (126.4 Gt), 54% (335.7 Gt), 22% (136.2 Gt) and 3% (18.7 Gt), respectively. We further project that, depending on future emissions pathways, 17-34% of forested areas will experience climate conditions by the end of the century that currently support a different forest type, highlighting the intensification of climatic stress on existing forests. By quantifying the distribution of tree leaf types and their corresponding biomass, and identifying regions where climate change will exert greatest pressure on current leaf types, our results can help improve predictions of future terrestrial ecosystem functioning and carbon cycling

The global biogeography of tree leaf form and habit.

Understanding what controls global leaf type variation in trees is crucial for comprehending their role in terrestrial ecosystems, including carbon, water and nutrient dynamics. Yet our understanding of the factors influencing forest leaf types remains incomplete, leaving us uncertain about the global proportions of needle-leaved, broadleaved, evergreen and deciduous trees. To address these gaps, we conducted a global, ground-sourced assessment of forest leaf-type variation by integrating forest inventory data with comprehensive leaf form (broadleaf vs needle-leaf) and habit (evergreen vs deciduous) records. We found that global variation in leaf habit is primarily driven by isothermality and soil characteristics, while leaf form is predominantly driven by temperature. Given these relationships, we estimate that 38% of global tree individuals are needle-leaved evergreen, 29% are broadleaved evergreen, 27% are broadleaved deciduous and 5% are needle-leaved deciduous. The aboveground biomass distribution among these tree types is approximately 21% (126.4 Gt), 54% (335.7 Gt), 22% (136.2 Gt) and 3% (18.7 Gt), respectively. We further project that, depending on future emissions pathways, 17-34% of forested areas will experience climate conditions by the end of the century that currently support a different forest type, highlighting the intensification of climatic stress on existing forests. By quantifying the distribution of tree leaf types and their corresponding biomass, and identifying regions where climate change will exert greatest pressure on current leaf types, our results can help improve predictions of future terrestrial ecosystem functioning and carbon cycling

Native diversity buffers against severity of non-native tree invasions.

Determining the drivers of non-native plant invasions is critical for managing native ecosystems and limiting the spread of invasive species1,2. Tree invasions in particular have been relatively overlooked, even though they have the potential to transform ecosystems and economies3,4. Here, leveraging global tree databases5-7, we explore how the phylogenetic and functional diversity of native tree communities, human pressure and the environment influence the establishment of non-native tree species and the subsequent invasion severity. We find that anthropogenic factors are key to predicting whether a location is invaded, but that invasion severity is underpinned by native diversity, with higher diversity predicting lower invasion severity. Temperature and precipitation emerge as strong predictors of invasion strategy, with non-native species invading successfully when they are similar to the native community in cold or dry extremes. Yet, despite the influence of these ecological forces in determining invasion strategy, we find evidence that these patterns can be obscured by human activity, with lower ecological signal in areas with higher proximity to shipping ports. Our global perspective of non-native tree invasion highlights that human drivers influence non-native tree presence, and that native phylogenetic and functional diversity have a critical role in the establishment and spread of subsequent invasions

Native diversity buffers against severity of non-native tree invasions

Determining the drivers of non-native plant invasions is critical for managing native ecosystems and limiting the spread of invasive species1,2. Tree invasions in particular have been relatively overlooked, even though they have the potential to transform ecosystems and economies3,4. Here, leveraging global tree databases5-7, we explore how the phylogenetic and functional diversity of native tree communities, human pressure and the environment influence the establishment of non-native tree species and the subsequent invasion severity. We find that anthropogenic factors are key to predicting whether a location is invaded, but that invasion severity is underpinned by native diversity, with higher diversity predicting lower invasion severity. Temperature and precipitation emerge as strong predictors of invasion strategy, with non-native species invading successfully when they are similar to the native community in cold or dry extremes. Yet, despite the influence of these ecological forces in determining invasion strategy, we find evidence that these patterns can be obscured by human activity, with lower ecological signal in areas with higher proximity to shipping ports. Our global perspective of non-native tree invasion highlights that human drivers influence non-native tree presence, and that native phylogenetic and functional diversity have a critical role in the establishment and spread of subsequent invasions

Evenness mediates the global relationship between forest productivity and richness

1. Biodiversity is an important component of natural ecosystems, with higher species richness often correlating with an increase in ecosystem productivity. Yet, this relationship varies substantially across environments, typically becoming less pronounced at high levels of species richness. However, species richness alone cannot reflect all important properties of a community, including community evenness, which may mediate the relationship between biodiversity and productivity. If the evenness of a community correlates negatively with richness across forests globally, then a greater number of species may not always increase overall diversity and productivity of the system. Theoretical work and local empirical studies have shown that the effect of evenness on ecosystem functioning may be especially strong at high richness levels, yet the consistency of this remains untested at a global scale. 2. Here, we used a dataset of forests from across the globe, which includes composition, biomass accumulation and net primary productivity, to explore whether productivity correlates with community evenness and richness in a way that evenness appears to buffer the effect of richness. Specifically, we evaluated whether low levels of evenness in speciose communities correlate with the attenuation of the richness–productivity relationship. 3. We found that tree species richness and evenness are negatively correlated across forests globally, with highly speciose forests typically comprising a few dominant and many rare species. Furthermore, we found that the correlation between diversity and productivity changes with evenness: at low richness, uneven communities are more productive, while at high richness, even communities are more productive. 4. Synthesis. Collectively, these results demonstrate that evenness is an integral component of the relationship between biodiversity and productivity, and that the attenuating effect of richness on forest productivity might be partly explained by low evenness in speciose communities. Productivity generally increases with species richness, until reduced evenness limits the overall increases in community diversity. Our research suggests that evenness is a fundamental component of biodiversity–ecosystem function relationships, and is of critical importance for guiding conservation and sustainable ecosystem management decisions