Simone Matias Reis

VEGETATION SUCCESSION IN THE CERRADO–AMAZONIAN FOREST TRANSITION ZONE OF MATO GROSSO STATE, BRAZIL

The occurrence of cerrado (as tree and shrub savanna is called in Brazil) and forest formations side by side is common at the southern margin of the Brazilian Amazonian Forest, and previous studies have demonstrated the advance of forests over cerrado areas. The aim of the present study is to provide an accurate documentation of the transition process between the two major biomes. Tree data (≥ 5 cm diameter at 0.3 m above soil level) from three plots of cerrado sensu stricto lying near three of cerradao (the taller, denser form of cerrado ) were inventoried starting in 2002 in an area of 1.5 ha made up of 150 subplots of 10 × 10 m (50 in each area). This showed that the most important species of the cerradao were invading areas previously occupied by smaller, lower forms of cerrado (although it is sometimes difficult to define which are ‘forest’ and which ‘ cerrado ’ species as many are flexible in size – for instance Emmotum nitens can often be intermediate, establishing in cerrado that develops into cerradao and on to forest). Some typical species such as Eriotheca gracilipes and Emmotum nitens , established since the first inventories, have increased their populations (between 27 and 210%). Tachigali vulgaris , a typical, weedy, adventive species of the Cerrado–Amazonian Forest transition, showed the largest increase in abundance in areas of cerrado sensu stricto (between 100 and 1200%), and is probably the most important pioneer species in the initial advance of the forest into cerrado at the Southern Amazonian border.

Examining variation in the leaf mass per area of dominant species across two contrasting tropical gradients in light of community assembly

Abstract Understanding variation in key functional traits across gradients in high diversity systems and the ecology of community changes along gradients in these systems is crucial in light of conservation and climate change. We examined inter‐ and intraspecific variation in leaf mass per area (LMA) of sun and shade leaves along a 3330‐m elevation gradient in Peru, and in sun leaves across a forest–savanna vegetation gradient in Brazil. We also compared LMA variance ratios (T‐statistics metrics) to null models to explore internal (i.e., abiotic) and environmental filtering on community structure along the gradients. Community‐weighted LMA increased with decreasing forest cover in Brazil, likely due to increased light availability and water stress, and increased with elevation in Peru, consistent with the leaf economic spectrum strategy expected in colder, less productive environments. A very high species turnover was observed along both environmental gradients, and consequently, the first source of variation in LMA was species turnover. Variation in LMA at the genus or family levels was greater in Peru than in Brazil. Using dominant trees to examine possible filters on community assembly, we found that in Brazil, internal filtering was strongest in the forest, while environmental filtering was observed in the dry savanna. In Peru, internal filtering was observed along 80% of the gradient, perhaps due to variation in taxa or interspecific competition. Environmental filtering was observed at cloud zone edges and in lowlands, possibly due to water and nutrient availability, respectively. These results related to variation in LMA indicate that biodiversity in species rich tropical assemblages may be structured by differential niche‐based processes. In the future, specific mechanisms generating these patterns of variation in leaf functional traits across tropical environmental gradients should be explored.

DESENVOLVIMENTO INICIAL E QUALIDADE DE MUDAS DE Copaifera langsdorffii Desf. SOB DIFERENTES NÍVEIS DE SOMBREAMENTO

As florestas de galeria vem sendo fragmentadas, levando a perda de sua elevada diversidade, tornando-se imprescindiveis estudos que avaliem o comportamento ecologico de suas especies arboreas. O presente estudo teve como objetivo testar a hipotese de que a producao de mudas de Copaifera langsdorffii e influenciada pela luminosidade do ambiente, apresentando maior qualidade e desenvolvimento inicial em niveis intermediarios de luz. As plantas foram testadas em pleno sol, 30%, 50%, 70% e 90% de sombreamento, avaliando-se numero de folhas, altura e diâmetro aos 60, 90, 120 e 191 dias apos a emergencia (DAE) e massa seca aerea e radicular e, indice de qualidade de Dickson ao final do experimento (191 DAE). O efeito dos niveis de sombreamento foi analisado por meio de analise de regressao. As plantas apresentaram boa plasticidade de crescimento nos diferentes niveis de luminosidade, mas com melhor desenvolvimento e qualidade (IQD) em 50% de sombreamento, corroborando a hipotese testada. A luminosidade ou sombreamento excessivo devem ser evitados para garantir a producao de mudas mais vigorosas de Copaifera langsdorffii. Assim, recomenda-se a producao de mudas desta especie sob 50% de sombreamento para favorecer a sua qualidade e possivelmente garantir melhor sobrevivencia em campo.

Climate and fragmentation affect forest structure at the southern border of Amazonia

ABSTRACT Background: The remaining forests in the extensive contact zone between southern Amazonia (seasonal rain forest) and the Cerrado (savanna) biomes are at risk due to intense land-use and climate change. Aims: To explore the vulnerability of these transitional forests to changes in land use and climate, we evaluated the effects of fragmentation and climatic variables on forest structure. Methods: We measured the diameter and height of 14,185 trees with diameter ≥10 cm at 24 forest plots distributed over an area of 25,000 km2. For each plot, we obtained data on contemporary fragmentation and climatic variables. Results: Forest structure variables (height, diameter, height:diameter allometry, biomass) varied significantly both within and among plots. The height, H:D and biomass of trees were positively correlated with annual precipitation and fragment area. Conclusions: The association between forest structure and precipitation indicates that these forests plots are likely to be vulnerable to dry season intensification anticipated for the southern edge of the Amazon. Additionally, the reduction in the fragment area may contribute to reductions in forest biomass and tree height, and consequently ecosystem carbon stocks. Given the likely susceptibility of these forests, urgent conservation action is needed to prevent further habitat degradation.

Tree diversity and above-ground biomass in the South America Cerrado biome and their conservation implications

Less than half of the original two million square kilometers of the Cerrado vegetation remains standing, and there are still many uncertainties as to how to conserve and prioritize remaining areas effectively. A key limitation is the continuing lack of geographically-extensive evaluation of ecosystem-level properties across the biome. Here we sought to address this gap by comparing the woody vegetation of the typical cerrado of the Cerrado–Amazonia Transition with that of the core area of the Cerrado in terms of both tree diversity and vegetation biomass. We used 21 one-hectare plots in the transition and 18 in the core to compare key structural parameters (tree height, basal area, and above-ground biomass), and diversity metrics between the regions. We also evaluated the effects of temperature and precipitation on biomass, as well as explored the species diversity versus biomass relationship. We found, for the first time, both that the typical cerrado at the transition holds substantially more biomass than at the core, and that higher temperature and greater precipitation can explain this difference. By contrast, plot-level alpha diversity was almost identical in the two regions. Finally, contrary to some theoretical expectations, we found no positive relationship between species diversity and biomass for the Cerrado woody vegetation. This has implications for the development of effective conservation measures, given that areas with high biomass and importance for the compensation of greenhouse gas emissions are often not those with the greatest diversity.

Dynamics of the woody vegetation of two areas of Cerrado sensu stricto located on different substrates

Differences in substrates can provoke distinct responses in the dynamics of a plant community. We compared changes the floristic, structural and dynamic parameters of the woody vegetation between burned sites dominated by cerrado tipico (CT) and cerrado rupestre (CR), which is characterized by the presence of rocky outcrops, over time. We set up 10 plots (20 m × 50 m) at each site. All individuals (diameter of ≥ 3 cm at 30 cm height above the ground) were identified in the two censuses (2009 and 2012) and measured (stem diameter), after an accidental fire in 2008. Changes in floristic parameters between the CT and CR were not significant. However, we found significant differences (p < 0.05) in structural and dynamic parameters, such as density (CT = 1,523; CR = 2,171 ind.ha-1), basal area (CT = 8.70; CR = 13.00 m2.ha-1), recruitment rates (CT = 24.35; CR = 15.14% year-1; p = 0.01), gain (CT = 8.58; CR= 3.58% year-1), and the loss rates of basal area (CT = 3.88; CR= 2.45% year-1). These differences emphasize the need for a differential evaluation of these sites for the development of effective conservation strategies.