Climate change will reduce suitable Caatinga dry forest habitat for endemic plants with disproportionate impacts on specialized reproductive strategies

Global climate change alters the dynamic of natural ecosystems and directly affects species distributions, persistence and diversity. The impacts of climate change may lead to dramatic changes in biotic interactions, such as pollination and seed dispersal. Life history traits are extremely important to consider the vulnerability of a species to climate change, producing more robust models than those based primarily on species distributions. Here, we hypothesized that rising temperatures and aridity will reduce suitable habitats for the endemic flora of the Caatinga, the most diverse dry tropical forest on Earth. Specifically, species with specialized reproductive traits (e.g. vertebrate pollination, biotic dispersal, obligatory cross-pollination) should be more affected by climate change than those with generalist traits. We performed two ecological niche models (current and future) to simulate the effects of climate change on the distribution area of endemic species in relation to life-history traits. We used the MIROC-ESM and CCSM4 models for both intermediate (RCP4.5) and highest predicted (RCP8.5) GHG emission scenarios, with a resolution of 30' (~1 km2). Habitat with high occurrence probability (>80%) of endemic species will be reduced (up to ~10% for trees, ~13% for non-arboreous, 10-28% for species with any pollination/reproductive system), with the greatest reductions for species with specialized reproductive traits. In addition, the likely concentration of endemic plants in the extreme northeastern portion of the Caatinga, in more mesic areas, coincides with the currently most human-modified areas of the ecosystem, which combined with climate change will further contract suitable habitats of endemic species. In conclusion, plant species endemic to the Caatinga are highly vulnerable to even conservative scenarios of future climate change and may lose much of their climatic envelopes. New protected areas should be located in the northeastern portion of the Caatinga, which hosts a more favorable climate, but is currently exposed to escalating agricultural intensification

Markedly Divergent Tree Assemblage Responses to Tropical Forest Loss and Fragmentation across a Strong Seasonality Gradient

We examine the effects of forest fragmentation on the structure and composition of tree assemblages within three seasonal and aseasonal forest types of southern Brazil, including evergreen, Araucaria, and deciduous forests. We sampled three southernmost Atlantic Forest landscapes, including the largest continuous forest protected areas within each forest type. Tree assemblages in each forest type were sampled within 10 plots of 0.1 ha in both continuous forests and 10 adjacent forest fragments. All trees within each plot were assigned to trait categories describing their regeneration strategy, vertical stratification, seed-dispersal mode, seed size, and wood density. We detected differences among both forest types and landscape contexts in terms of overall tree species richness, and the density and species richness of different functional groups in terms of regeneration strategy, seed dispersal mode and woody density. Overall, evergreen forest fragments exhibited the largest deviations from continuous forest plots in assemblage structure. Evergreen, Araucaria and deciduous forests diverge in the functional composition of tree floras, particularly in relation to regeneration strategy and stress tolerance. By supporting a more diversified light-demanding and stress-tolerant flora with reduced richness and abundance of shade-tolerant, old-growth species, both deciduous and Araucaria forest tree assemblages are more intrinsically resilient to contemporary human-disturbances, including fragmentation-induced edge effects, in terms of species erosion and functional shifts. We suggest that these intrinsic differences in the direction and magnitude of responses to changes in landscape structure between forest types should guide a wide range of conservation strategies in restoring fragmented tropical forest landscapes worldwide

Habitat fragmentation and the future structure of tree assemblages in a fragmented Atlantic forest landscape

The biodiversity value of human-modified landscapes has become a central question in the tropical forest conservation biology, yet the degree to which plant populations and communities are restructured in response to environmental change remains unclear. Here, we address tree species density in a fragmented Atlantic forest landscape to test the hypothesis that tree assemblages inhabiting edge-dominated forest habitats approach typical conditions of early successional systems. Seedlings and adults from 141 tree species were sampled across 39 0.1-ha plots: 19 in small fragments (55 % of all tree species exhibiting higher densities in small fragments than in mature forest, particularly pioneers (>60 % of all species). Seedlings and adults of these proliferating species differed from species exhibiting population declines in terms of wood density and seed size, respectively. Additionally, pioneers were more abundant than shade-tolerant species, as were hardwood species in the case of seedlings. Tree species showing highest population increases consisted largely of long-lived, light-demanding canopy species bearing soft or hardwood and small-to-medium-sized seeds. Tree assemblage structure also differed in terms of forest habitats with small forest fragments supporting few rare species, whereas the most rapidly proliferating species were much more widespread and abundant in fragments. However, 60 % of all adult pioneer species recorded in small fragments were not recorded as seedlings in this habitat type, although both seedling and adult assemblages were dominated by pioneer species. Edge-dominated tree assemblages are likely to experience long-term shifts toward greater dominance of long-lived, pioneer canopy species

Human disturbances reduce tree abundance and stimulate woody plant resprouting and clonal growth in a tropical dry forest

In environments under chronic human disturbance, the persistence of woody plants via both resprouting of new shoots and clonal growth via new root suckers can increase survival and fitness. However, the relative frequency and importance of these mechanisms following disturbance remain poorly explored. Here we simulated both wood extraction (partial aboveground biomass (AGB) removal) and slash-and-burn (complete AGB removal plus burn) practices in situ and compare their effects versus controls after six months on the persistence (resprouting from new shoots and clonal growth via new root suckers), biomass, and structure (height, diameter at ground level, and number of stems) of six dominant tree species (n = 210). Tree regeneration following slash-and-burn varied from 0–80% across species. Half regenerated exclusively via clonal growth, one via resprouting, and one via both mechanisms. Increased disturbance intensity (control < wood extraction < slash-and-burn) resulted in at least fivefold more root suckers produced. Nevertheless, slash-and-burn led to the apparent mortality of nearly 70% of trees (i.e., absence of living aboveground tissue after six months). For those trees that did show evidence of regeneration, initial biomass recovery was nearly 5%, mainly from resprouting of new shoots. Our findings support the presence of persistence mechanisms after human disturbances in a relatively high proportion of woody plant species in the Caatinga dry forest. In the context of limited seed germination and seedling recruitment, resprouting and clonal growth may have a more significant role in regeneration dynamics than previously thought. Regeneration ability must be considered when choosing species for restoration purposes, especially in disturbed landscapes

Richness of gall morphospecies along a secondary successional gradient of Atlantic Forest in northeastern Brazil

Galling insects have been recommended as an excellent tool to evaluate environmental changes and habitat quality. In this study, we assessed the richness of gall morphospecies, as well as host-plant richness and abundance, to detect environmental changes in six patches of secondary Atlantic Forest in Northeast Brazil. The patches of forest varied in age (between 25 and 42 yrs) and size. In each patch, the plants between 1 and 3 meters tall were evaluated for a period of one hour, totaling six hours. A total of 50 gall morphospecies were found on 37 host-plant species (88 plant individuals). We identified 27 (72%) host-plant species belonging to 19 plant families. Richness of gall morphospecies and host-plant richness and abundance were not significantly affected by the age and size of the patch. However, the richness of gall morphospecies increased significantly as the host-plant percentage of shade-tolerant trees increased. Considering that the differences observed in this study, between younger and older patches, developed in a relatively short time period of forest recovery (c. 18 yrs), and that some host-plant species occurred exclusively in older patches, this study showed that gall-inducing insects are a good tool for evaluating changes in a secondary successional gradient. The use of gall-inducing insects as bioindicators in restoration and conservation programs is not only a good opportunity to advance this type of study but is also a useful application, at local and regional scales, to monitor the successional progress of forests.(Riqueza de morfoespécies de galhas ao longo de um gradiente sucessional em trechos de floresta Atlântica secundária no nordeste do Brasil). Insetos galhadores têm sido indicados como uma excelente ferramenta para avaliar as mudanças ambientais e a qualidade do habitat. Neste estudo, a riqueza de morfoespécies de galhas como também a riqueza e abundância de plantas hospedeiras foram avaliadas para detectar possíveis mudanças ambientas em seis trechos de floresta secundária em um remanescente de Floresta Atlântica localizado no nordeste do Brasil. Os trechos apresentaram diferentes tamanhos e idades de regeneração (entre 25 e 42 anos). Em cada trecho, as plantas entre 1-3 metros de altura foram inspecionadas durante uma hora, totalizando seis horas. Um total de 50 morfoespécies foi encontrado em 37 plantas hospedeiras (88 indivíduos). Foram identificadas 27 (72%) plantas distribuídas em 19 famílias. A riqueza de morfoespécies e a riqueza e abundância de plantas hospedeiras não foram afetadas com a idade de regeneração ou pelo tamanho do trecho. Porém, a riqueza de morfoespécies aumentou significantemente aumentando a porcentagem de plantas hospedeiras tolerantes à sombra. Considerando que nossos resultados foram observados em um curto intervalo sucessional (ca. 18 anos), e que algumas das plantas hospedeiras ocorreram exclusivamente em trechos mais avançados, é possível indicar os insetos galhadores como uma eficiente ferramenta de biomonitoramento. O uso destes insetos como bioindicadores em programas de restauração e conservação não é apenas uma boa oportunidade para avançar os estudos e tornar sua aplicação viável em uma escala local e regional, mas também decisivo no monitoramento do progresso sucessional

Occurrence of gall complexes along a topographic gradient in an undisturbed lowland forest of central Amazonia

The species richness of gall-inducing insects and their host plants, in an undisturbed lowland forest in central Amazonia, was analyzed to test whether there is a higher occurrence of galls in mesic campinarana habitats when compared to plateaus, slopes and valleys. In October 2005, 300 plants, which were 1 to 2 meters tall, were sampled along ten transects (5 meters wide) per habitat. Gall-inducing insects were found in only 35 (3%) of the 1200 plants studied. Thirteen families, eight genera and 27 morphospecies of plants were identified. The families Burseraceae and Rubiaceae had the highest number of host plant species. There was no significant difference in species richness between habitat types. However, the gall-inducing insects and host plant species were exclusive to each habitat. Furthermore, the frequency of host plants in campinarana was not higher when compared to the other habitats. Probably, tree canopies present more structural complexity, light availability and incidence of leaves with scleromorphic characteristics than understory plants, resulting in vertical stratification with a higher amount of gall-inducing insects in canopies when compared with individuals of the same species in the understory. The higher plant diversity and variation of physical characteristics of the forests in central Amazonia can help explain why specific interactions and the frequency of gall-inducing insects were found in each habitat. The results of this study indicate that central Amazonian forests have a high diversity of gall-inducing insects with an exclusive fauna related to each habitat, which is potentially due to the greater environmental heterogeneity, and suggests the importance of conducting additional studies about galling insects, principally in forest canopies.(Ocorrência de galhas ao longo de um gradiente topográfico em uma floresta de terra firma na Amazônia Central). A riqueza de insetos galhadores e plantas hospedeiras foram investigadas em uma floresta de terra firme, na Amazônia Central, para testar se haveria uma maior ocorrência de galhas em habitats mais secos, como campinarana, comparados aos platôs, vertentes e baixios. Em outubro de 2005, foram amostradas 300 plantas em 10 transecções (com 5 m de largura cada) por habitat, totalizando 1.200 plantas.  As galhas induzidas por insetos foram encontradas em apenas 35 (3%) das 1.200 plantas estudadas. Treze famílias, oito gêneros e 27 morfoespécies de plantas foram identificados, sendo que as famílias Burseraceae e Rubiaceae apresentaram maior número de espécies de plantas hospedeiras. Não foi observada nenhuma diferença significativa na riqueza de espécie de galhas induzidas por insetos entre os habitats, porém as interações foram exclusivas de cada habitat. Além disso, campinarana não apresentou maior frequência de plantas hospedeiras, em comparação aos outros habitats. Provavelmente, as copas das árvores apresentam maior complexidade estrutural, disponibilidade de luz e ocorrência de plantas com características escleromórficas do que o sob-bosque, resultando em uma estratificação vertical e maior frequência de galhas nas copas quando comparada com indivíduos da mesma espécie no sub-bosque. A alta diversidade vegetal e a variação abiótica podem explicar a especificidade e frequência de interações em cada habitat. Nossos resultados indicam que a vegetação da Amazônia Central apresenta uma alta riqueza de galhas entomógenas, além de um grande potencial para uma exclusiva fauna associada a cada habitat, devido a grande heterogeneidade ambiental, e recomenda o desenvolvimento de estudos com insetos galhadores, principalmente nas copas das árvores

ESTUDO COMPARATIVO DA VEGETAÇÃO DE DOIS TRECHOS DE FLORESTA SECUNDÁRIA NO NUCLEO SANTA VIRGINIA. PARQUE ESTADUAL DA SERRA DO MAR, SP

O objetivo deste estudo é caracterizar alguns dos processos envolvidos na sucessão secundária da floresta ombrófila densa montana, em uma área no Núcleo Santa Virgínia, município de São Luiz do Paraitinga, SP. Através do método de parcelas, foram amostradas duas áreas de floresta secundária, uma com aproximadamente quinze anos e a outra entre vinte e cinco e trinta anos de idade. A análise dos dados revelou modificações na composição florística e na estrutura da comunidade e das populações, bem como modificações na importância dos grupos funcionais e das síndromes de dispersão de propágulos

ASPECTOS DA SUCESSÃO SECUNDÁRIA EM TRECHO DA FLORESTA ATLÂNTICA NO PARQUE ESTADUAL DA SERRA DO MAR, SP

O objetivo deste trabalho é discutir alguns aspectos da sucessão secundária na floresta atlântica através da caracterização e análise do desenvolvimento histórico de um trecho de floresta secundária, no Núcleo Santa Virgínia, São Luiz do Paraitinga, SP. Foram encontradas quarenta e seis espécies pertencentes a vinte e duas famílias botânicas, sendo que dez espécies foram classificadas como pioneiras, treze como secundárias e vinte e três espécies como típicas de sub-bosque. A maioria das espécies apresentou síndrome de dispersão por animais. O padrão sucessional descrito, apresenta similaridade com outros padrões sucessionais apresentados para a floresta ombrófila densa no Sul e Sudeste do Brasil

Markedly divergent tree assemblage responses to tropical forest loss and fragmentation across a strong seasonality gradient

We examine the effects of forest fragmentation on the structure and composition of tree assemblages within three seasonal and aseasonal forest types of southern Brazil, including evergreen, Araucaria, and deciduous forests. We sampled three southernmost Atlantic Forest landscapes, including the largest continuous forest protected areas within each forest type. Tree assemblages in each forest type were sampled within 10 plots of 0.1 ha in both continuous forests and 10 adjacent forest fragments. All trees within each plot were assigned to trait categories describing their regeneration strategy, vertical stratification, seed-dispersal mode, seed size, and wood density. We detected differences among both forest types and landscape contexts in terms of overall tree species richness, and the density and species richness of different functional groups in terms of regeneration strategy, seed dispersal mode and woody density. Overall, evergreen forest fragments exhibited the largest deviations from continuous forest plots in assemblage structure. Evergreen, Araucaria and deciduous forests diverge in the functional composition of tree floras, particularly in relation to regeneration strategy and stress tolerance. By supporting a more diversified light-demanding and stress-tolerant flora with reduced richness and abundance of shadetolerant, old-growth species, both deciduous and Araucaria forest tree assemblages are more intrinsically resilient to contemporary human-disturbances, including fragmentationinduced edge effects, in terms of species erosion and functional shifts. We suggest that these intrinsic differences in the direction and magnitude of responses to changes in landscape structure between forest types should guide a wide range of conservation strategies in restoring fragmented tropical forest landscapes worldwide

A RECUPERAÇÃO DA FLORESTA ATLÂNTICA SOB PLANTIOS DE EUCALYPTUS NO NÚCLEO SANTA VIRGÍNIA - SP

Este trabalho objetiva avaliar o papel de uma floresta de Eucalyptus spp, na recuperação da floresta nativa, buscando subsídios para o manejo destes povoamentos no Núcleo Santa Virgínía, São Luiz do Paraitinga, SP. Através do uso de parcelas lançadas ao acaso, foram amostrados três trechos da floresta implantada. A análise dos dados revelou que o sub-bosque desta floresta apresenta um padrão sucessional em forma de mosaico, onde coexistem áreas ricas em espécies nativas de diferentes grupos ecológicos, com áreas desprovidas de vegetação arbórea. O zoneamento, com base na regeneração natural, parece ser a alternativa mais adequada ao manejo do reflorestamento