Diel and seasonal stem growth responses to climatic variation are consistent across species in a subtropical tree community.

Understanding how intra-annual stem growth responds to atmospheric and soil conditions is essential for assessing the effects of climate extremes on forest productivity. In species-poor forests, such understanding can be obtained by studying stem growth of the dominant species. Yet, in species-rich (sub-)tropical forests, it is unclear whether these responses are consistent among species. We monitored intra-annual stem growth with high-resolution dendrometers for 27 trees belonging to 14 species over 5 yr in a montane subtropical forest. We quantified diel and seasonal stem growth patterns, verified to what extent observed growth patterns coincide across species and analysed their main climatic drivers. We found very consistent intra-annual growth patterns across species. Species varied in the rate but little in the timing of growth. Diel growth patterns revealed that - across species - trees mainly grew before dawn when vapour pressure deficit (VPD) was low. Within the year, trees mainly grew between May and August driven by temperature and VPD, but not by soil moisture. Our study reveals highly consistent stem growth patterns and climatic drivers at community level. Further studies are needed to verify whether these results hold across climates and forests, and whether they can be scaled up to estimate forest productivity.

Niche breadth of Amazonian trees increases with niche optimum across broad edaphic gradients.

Understanding how biotic interactions and environmental filtering mediated by soil properties shape plant community assembly is a major challenge in ecology, especially when studying complex and hyperdiverse ecosystems like tropical forests. To shed light on the influence of both factors, we examined how the edaphic optimum of species (their niche position) related to their edaphic range (their niche breadth) along different environmental gradients and how this translates into functional strategies. Here we tested four scenarios describing the shape of the niche breadth-niche position relationship, including one neutral scenario and three scenarios proposing different relative influences of abiotic and biotic factors on community assembly along a soil resource gradient. To do so, we used soil concentration data for five key nutrients (N, P, Ca, Mg, and K), along with accurate measurements of 14 leaf, stem, and root traits for 246 tree species inventoried in 101 plots located across Eastern (French Guiana) and Western (Peru) Amazonia. We found that species niche breadth increased linearly with species niche position along each soil nutrient gradient. This increase was associated with more resource acquisitive traits in the leaves and the roots for soil N, Ca, Mg, and K concentration, while it was negatively associated with wood density for soil P concentration. These observations agreed with one of our hypothetical scenarios in which species with resource conservation traits are confined to the most nutrient-depleted soils (abiotic filter), but they are outperformed by faster-growing species in more fertile conditions (biotic filter). Our results refine and strengthen support for niche theories of species assembly while providing an integrated approach to improving forest management policies.

Differences in soil organic matter between EcM- and AM-dominated forests depend on tree and fungal identity.

As global change shifts the species composition of forests, we need to understand which species characteristics affect soil organic matter (SOM) cycling to predict future soil carbon (C) storage. Recently, whether a tree species forms a symbiosis with arbuscular (AM) versus ectomycorrhizal (EcM) fungi has been suggested as a strong predictor of soil C storage, but there is wide variability within EcM systems. In this study, we investigated how mycorrhizal associations and the species composition of canopy trees and mycorrhizal fungi related to the proportion of soil C and nitrogen (N) in mineral associations and soil C:N across four sites representing distinct climates and tree communities in the eastern US broadleaf forest biome. In two of our sites, we found the expected relationship of declining mineral-associated C and N and increasing soil C:N ratios as the basal area of EcM-associating trees increased. However, across all sites these soil properties strongly correlated with canopy tree and fungal species composition. Sites where the expected pattern with EcM basal area was observed were (1) dominated by trees with lower quality litter in the Pinaceae and Fagaceae families and (2) dominated by EcM fungi with medium-distance exploration type hyphae, melanized tissues, and the potential to produce peroxidases. This observational study demonstrates that differences in SOM between AM and EcM systems are dependent on the taxa of trees and EcM fungi involved. Important information is lost when the rich mycorrhizal symbiosis is reduced to two categories.

30 Years of postdisturbance recruitment in a Neotropical forest.

QUESTIONS: Long-term community response to disturbance can follow manifold successional pathways depending on the interplay between various recruitment processes. Analyzing the succession of recruited communities provides a long-term perspective on forest response to disturbance. Specifically, postdisturbance recruitment trajectories assess (a) the successive phases of postdisturbance response and the role of deterministic recruitment processes, and (b) the return to predisturbance state of recruits taxonomic/functional diversity/composition. LOCATION: Amazonian rainforest, Paracou station, French Guiana. METHODS: We analyzed trajectories of recruited tree communities, from twelve forest plots of 6.25 ha each, during 30 years following a disturbance gradient that ranged from 10% to 60% of aboveground biomass removed. We measured recruited community taxonomic composition turnover, compared to whole predisturbance community, and assessed their functional composition by measuring the community weighted means for seven leaf, stem, and life-history functional traits. We also measured recruited community taxonomic richness, taxonomic evenness, and functional diversity and compared them to the diversity values from a random recruitment process. RESULTS: While control plots trajectories resembled random recruitment trajectories, postdisturbance trajectories diverged significantly. This divergence corresponded to an enhanced recruitment of light-demanding species that became dominant above a disturbance intensity threshold. After breakpoints in time, though, recruitment trajectories returned to diversity values and composition similar to those of predisturbance and control plots community. CONCLUSIONS: Following disturbance, recruitment processes specific to undisturbed community were first replaced by the emergence of more restricted, deterministic recruitment processes favoring species with efficient light use and acquisition. Then, a second phase corresponded to a decades-long recovery of recruits predisturbance taxonomic and functional diversity and composition that remained unachieved after 30 years.

Structural and compositional shifts in Cerrado fragments in up to 11 years monitoring

The Cerrado has a wide diversity of fauna and flora, and the knowledge of its horizontal structure, in different time intervals allows the prediction of its structural and floristic characteristics. The aim of this study was to evaluate the changes in structure and composition of tree community in three fragments of Cerrado with low anthropization, in an interval of 11 years at Minas Gerais state. Rectangular plots of fixed size were sampled, measuring stem diameter and height of all living arboreal individuals with diameter at 1.30 meters above ground (DBH) ≥ 5 cm. The tree vegetation dynamics study of the areas was performed, as well as the floristic analysis and the diametric structure. Considering all fragments and years of measurement, the recruitment of trees surpassed its mortality. The basal area varied between 3.67 and 13.07 m².ha-1. The studied areas, considering all fragments and years of measurement, showed a Shannon diversity index (H') from 3.43 to 3.87 nat.ind-1 and Pielou equitability index (J') ranged an interval between 0.77 and 0.82. The similarity calculated by the Jaccard index (J), when performed per plot considering the three fragments, showed a value of 0.2653. Also, related to the development and growth of the study areas, it can be inferred that all fragments and their respective years of measurement had a J-inverse pattern. In conclusion, it can be inferred that the three fragments maintained a representative growth in number of individuals and basal area.

Trees of Amazonian Ecuador: a taxonomically verified species list with data on abundance and distribution.

We compiled a data set for all tree species collected to date in lowland Amazonian Ecuador in order to determine the number of tree species in the region. This data set has been extensively verified by taxonomists and is the most comprehensive attempt to evaluate the tree diversity in one of the richest species regions of the Amazon. We used four main sources of data: mounted specimens deposited in Ecuadorian herbaria only, specimen records of a large-scale 1-hectare-plot network (60 plots in total), data from the Missouri Botanical Garden Tropicos® database (MO), and literature sources. The list of 2,296 tree species names we provide in this data set is based on 47,486 herbarium records deposited in the following herbaria: Alfredo Paredes Herbarium (QAP), Catholic University Herbarium (QCA), Herbario Nacional del Ecuador (QCNE), Missouri Botanical Garden (MO), and records from an extensive sampling of 29,768 individuals with diameter at breast height (dbh) ≥10 cm recorded in our plot network. We also provide data for the relative abundance of species, geographic coordinates of specimens deposited in major herbaria around the world, whether the species is native or endemic, current hypothesis of geographic distribution, representative collections, and IUCN threat category for every species recorded to date in Amazonian Ecuador. These data are described in Metadata S1 and can be used for macroecological, evolutionary, or taxonomic studies. There are no copyright restrictions; data are freely available for noncommercial scientific use (CC BY 3.0). Please see Metadata S1 (Class III, Section B.1: Proprietary restrictions) for additional information on usage.

Aplicação da diversidade alfa e beta para definição de áreas prioritárias para conservação: uma análise das florestas deciduais sobre afloramentos calcários no Vale do Paranã, Goiás / Use of alpha and beta diversity as a base to select priority areas for conservation: an analysis of the dry forests on limestone outcrops in Paranã Valley, Goiás state, Brazil

A organização das comunidades e suas afinidades florísticas podem ser analisadas por parâmetros de diversidade e servir como base para a seleção de áreas prioritárias para conservação. No Vale do Paranã, Nordeste de Goiás, as Florestas Estacionais Deciduais sobre afloramento calcário ocorrem intercaladas com vegetação de cerrado e são áreas preferenciais para agropecuária e mineração. Neste trabalho foram analisadas as diversidades alfa (índice de diversidade de Shannon) e beta (coeficientes de similaridade de Sørensen e Czekanowski) das comunidades arbóreas de seis fragmentos de Floresta Estacional Decidual sobre afloramentos calcários, para auxiliar na definição de áreas prioritárias para conservação. A partir das análises foram selecionados três dos seis fragmentos, cujos critérios para sua seleção foram: (1) Fazenda. Nica ­ Guarani que apresentou os maiores valores de diversidade alfa e riqueza e densidade de espécies ameaçadas; (2) Fazenda. Forquilha ­ Monte Alegre, com elevados valores de diversidade alfa e beta (dissimilaridade florística); e (3) Fazenda São José ­ São Domingos, com os maiores valores de diversidade beta, sendo o mais dissimilar floristicamente de todos os demais. O método empregado é promissor na definição de áreas prioritárias para conservação, sendo capaz de representar bem as diferenciações florísticas e estruturais de uma mesma fisionomia no espaço geográfico.

The diversity parameters used to analyze community organization and floristics relationships can be used as a base to select priority areas for conservation. At the Paranã valley in northeastern Goiás State, Central Brazil, the seasonally dry tropical forests growing on limestone outcrops form a mosaic with the cerrado vegetation being preferential for conversion to cattle ranging and mining. Alpha (Shannon diversity index) and beta (Sørensen and Czekanowski similarity coefficients) diversity were analyzed for the tree layer of six fragments of dry forests on limestone outcrops aiming the definition of priority areas for conservation. Based on the results, three of the six fragments analyzed were selected: (1) Nica farm ­ Guarani (GUA) which showed the highest values of alpha and diversity plus density of threatened vegetation. (2), Forquilha farm ­ Monte Alegre (MAL) with high values of alpha and beta diversity and (3) São José farm ­ São Domingos (SD_SJ) with the highest beta diversity, therefore, the most dissimilar. This method detected well the variations in floristics and structure of a physiognomy along a geographical gradient and seems promising for the definition of priority areas for conservation.

Resposta da comunidade de formigas aos atributos dos fragmentos e da vegetação em uma paisagem da Floresta Atlântica nordestina / Response of the ant community to attributes of fragments and vegetation in a northeastern Atlantic Rain Forest area, Brazil

The objective of this study was to determine the effects of forest fragmentation on ant richness in a landscape of Atlantic Forest in Northeast Brazil. More specifically, the ant richness was related to the attributes of fragments (area and distance from the fragment central point to the edge), landscape (forest cover surrounding the fragments), and tree community (plant density, richness, and percentage of shade tolerant species). The surveys were carried out in 19 fragments located in Alagoas State from October 2007 to March 2008. Samples were collected through a 300 m transect established in the center of each fragment, where 30 1-m² leaf litter samples were collected at 10 m intervals. A total of 146 ant species was collected, which belonged to 42 genera, 24 tribes and nine subfamilies. The attributes of fragments and landscape did not influence ant richness. On the other hand, tree density explained ca. 23 percent of ant richness. In relation to functional groups, both density and richness of trees explained the richness of general myrmicines (the whole model explained ca. 42 percent of the variation in this group) and percentage of shade tolerant trees explained the richness of specialist predator ants (30 percent for the whole model). These results indicate that ant fauna is more influenced by vegetation integrity than by fragment size, distance to edge or forest cover surrounding fragments.

Importância dos remanescentes florestais de Embu (SP, Brasil) para a conservação da flora regional / Importance of Embu (SP, Brazil) forest fragments to conservation of regional flora

O objetivo deste trabalho foi avaliar o grau de conservação e a importância dos remanescentes florestais situados em Embu - SP para a manutenção da diversidade da flora local. Para tanto, realizou-se o mapeamento e a classificação prévia da cobertura vegetal da área, a fim de se selecionarem os fragmentos a serem avaliados. Para determinar o grau de conservação desses fragmentos, efetuou-se levantamento expedito, com ênfase na vegetação arbórea, no qual foram registrados a composição florística e alguns descritores fisionômicos e estruturais. Foram caracterizados nove fragmentos, cujas áreas variaram de aproximadamente quatro a 35 ha, totalizando 140 ha. Apesar de curto, o levantamento possibilitou o registro de 197 espécies, das quais 172 arbóreas e em sua maioria da Floresta Ombrófila Densa mas com algumas espécies da Floresta Estacional Semidecidual. Comparando a composição de espécies arbóreas encontradas nos fragmentos àquela presente na Reserva Florestal do Morro Grande - unidade de conservação localizada próxima à área de estudo - constatou-se a ocorrência de 95 espécies em comum às duas áreas e 65 espécies com ocorrência exclusiva nos fragmentos. Além disso, foram registradas sete espécies enquadradas em alguma das categorias estabelecidas pela lista de espécies ameaçadas no Estado de São Paulo, no Brasil e no mundo. Embora tenham ocorrido predominantemente nos fragmentos mais bem conservados, algumas dessas espécies também foram encontradas em fragmentos degradados, indicando que mesmo com o predomínio de florestas secundárias, a manutenção dos remanescentes de Embu contribui para a conservação de espécies ainda não protegidas na região. A presença de estrutura florestal também pode auxiliar na proteção dos recursos hídricos e edáficos, além de contribuir para a conectividade de áreas de floresta nativa, facilitando o fluxo gênico de espécies vegetais e animais e, conseqüentemente, a manutenção da biodiversidade da Floresta Atlântica.

The objective of this research was to evaluate the conservation status and the importance of forest remnants at Embu (SP, Brazil) for the maintenance of the local plant diversity. A previous classification of the vegetation cover was made with aerial photographs interpretation in order to guide the selection of the forest fragments to be evaluated. In a quick survey, the floristic composition (focused on tree species) and some structural and physiognomic descriptors were recorded to assess the conservation status of the vegetation. Nine remaining forests with areas between four and 35 ha were characterized, totaling 140 ha. Despite of the short time, 197 species were recorded, being 172 trees typical of the Ombrophilous Dense Forest and some species from the Seasonal Semideciduous Forest. Comparing the tree and shrub species between the remaining forests and the Morro Grande Reserve Forest - conservation unit located next to the study site - 95 species were found in common and 65 species exclusively occurring at Embu forests. Moreover, seven threatened species according to the state, national and world red lists were recorded. Although these seven species were mostly found in the more mature fragments, some were also found in disturbed ones, indicating that even with the massive occurrence of secondary forests, the maintenance of the forest remnants of Embu may help to preserve some species still not protected in the region. The forest can also contribute to protect water and soil resources and to connect native forest patches, facilitating the gene flow of plant and animal species and, consequently, promoting the maintenance of the Atlantic Forest biodiversity.

The arboreal component of a dry forest in Northeastern Brazil

The dry forests of northeastern Brazil are found near the coastal zone and on low, isolated mountains inland amid semi-arid vegetation. The floristic composition of these dry montane forests, as well as their relationship to humid forests (Atlantic forest sensu stricto) and to the deciduous thorn woodlands (Caatinga sensu stricto) of the Brazilian northeast are not yet well known. This paper sought to determine if the arboreal plants in a dry forest growing on a low mountain in the semi-arid inland region (Serra Negra, 8° 35’ - 8° 38’ S and 38° 02’ - 38° 04’ W) between the municipalities of Floresta and Inajá, state of Pernambuco have the same floristic composition and structure as that seen in other regional forests. In fifty 10 x 20 m plots all live and standing dead trees with trunk measuring > 5 cm diameter at breast height were measured. Floristic similarities between the forest studied and other regional forests were assessed using multivariate analysis. The results demonstrate that the dry forest studied can be classified into two groups that represent two major vegetational transitions: (1) a humid forest/dry forest transition; and (2) a deciduous thorn-woodland/ dry forest transition.

As florestas secas do Nordeste do Brasil são encontradas próximo à zona costeira, nos planaltos e em montanhas baixas e isoladas no interior do semi-árido nordestino. A composição dessas florestas secas e sua relação com as florestas úmidas (Floresta Atlântica sensu stricto) e a vegetação arbustivo-arbórea caducifólia espinhosa (Caatinga sensu stricto) do Nordeste do Brasil ainda não estão resolvidas. Este trabalho procura determinar se a flora arbórea da floresta seca que cresce em uma montanha baixa da região semi-árida localizada entre os municípios de Floresta e Inajá, Pernambuco (Serra Negra, 8° 35’ - 8° 38’ S e 38° 02’ - 38° 04’ W) apresenta a mesma composição florística e estrutura observada em outras florestas da região. Foram amostrados todos os indivíduos vivos ou mortos, ainda de pé, com diâmetro do tronco à altura do peito > 5 cm, presentes em 50 parcelas (10 x 20 m). A similaridade florística entre Serra Negra e outras florestas da região foram avaliadas usando análises multivariadas. Os resultados demonstram que as florestas secas englobam dois conjuntos florísticos que representam duas transições: (1) transição florestas úmidas/ florestas secas; e (2) transição vegetação arbustivo-arbórea caducifólia espinhosa/floresta seca, onde está localizada Serra Negra.