Matheus Henrique Nunes

Dinâmica de uma comunidade arbórea após enchente em fragmentos florestais no sul de Minas Gerais

In order to evaluate the impact of a catastrophic flooding on tree individuals, it was carried out, in 2007, evaluation of an alluvial area in Sao Sebastiao da Bela Vista, MG, where it was sampled five alluvial fragments and a riparian forest, which was inventoried in 2005. Results show that after the flooding, a short-term dynamics was characterized by a mortality rate higher than recruitment rate and loss rate was higher than gain rate in basal area. However, the structure of the community was not affected, because frequency of surviving and dead trees in the diametric classes was proportional to the initial number of individual in each class. The results allowed to conclude that although there was no alteration in the diametric structure, the tree community dynamics reflected the disturbance caused by the flooding.

Artificial Intelligence Procedures for Tree Taper Estimation within a Complex Vegetation Mosaic in Brazil

Tree stem form in native tropical forests is very irregular, posing a challenge to establishing taper equations that can accurately predict the diameter at any height along the stem and subsequently merchantable volume. Artificial intelligence approaches can be useful techniques in minimizing estimation errors within complex variations of vegetation. We evaluated the performance of Random Forest® regression tree and Artificial Neural Network procedures in modelling stem taper. Diameters and volume outside bark were compared to a traditional taper-based equation across a tropical Brazilian savanna, a seasonal semi-deciduous forest and a rainforest. Neural network models were found to be more accurate than the traditional taper equation. Random forest showed trends in the residuals from the diameter prediction and provided the least precise and accurate estimations for all forest types. This study provides insights into the superiority of a neural network, which provided advantages regarding the handling of local effects.

The major barriers to evidence-informed conservation policy and possible solutions

Abstract Conservation policy decisions can suffer from a lack of evidence, hindering effective decision‐making. In nature conservation, studies investigating why policy is often not evidence‐informed have tended to focus on Western democracies, with relatively small samples. To understand global variation and challenges better, we established a global survey aimed at identifying top barriers and solutions to the use of conservation science in policy. This obtained the views of 758 people in policy, practice, and research positions from 68 countries across six languages. Here we show that, contrary to popular belief, there is agreement between groups about how to incorporate conservation science into policy, and there is thus room for optimism. Barriers related to the low priority of conservation were considered to be important, while mainstreaming conservation was proposed as a key solution. Therefore, priorities should focus on convincing the public of the importance of conservation as an issue, which will then influence policy‐makers to adopt pro‐environmental long‐term policies.

The influence of disturbance on driving carbon stocks and tree dynamics of riparian forests in Cerrado

Aims Riparian forests in the Brazilian Cerrado, also known as gallery forests, are very heterogeneous in structure, species composition and ecological features due to strong and abrupt variations of soil, hydrological and topographic properties. However, what are the variables driving forest carbon stock and productivity, mortality and recruitment in disturbed gallery forests? Methods We used 36 permanent plots data from a gallery forest in the Brazilian Cerrado. We investigated how tree community dynamics vary in a gallery forest on two contrasting disturbance levels—logged and non‐logged—across a topographic gradient intrinsically related to differences in moisture conditions, edge effects, as well as soil fertility and texture. Important Findings Soil variables were reduced into principal components and we used structural equation modelling to disentangle covarying variables. We also included carbon stocks as a determinant variable of dynamics rates. Logged forest had 50% higher productivity than non‐logged forest and streamside forest had aboveground carbon stocks 70% higher than the forest edge. Both logging and natural disturbance drove variation in the carbon stocks which contributed to shaping productivity and recruitment rates. Distance from the river also drove mortality and carbon stock rates. Areas with high‐carbon stocks favoured higher competition and lessened productivity and recruitment rates. Although soil fertility and texture are considered crucial components shaping forest dynamics, there was no clear influence of those variables on the present forest, probably because the strong effects of soil moisture, forest edge and disturbance disrupted the correlation between soil and forest dynamics.

Ten‐year assessment of the 100 priority questions for global biodiversity conservation

In 2008, a group of conservation scientists compiled a list of 100 priority questions for the conservation of the worlds biodiversity. However, now almost a decade later, no one has yet published a study gauging how much progress has been made in addressing these 100 high-priority questions in the peer-reviewed literature. We took a first step toward reexamining the 100 questions to identify key knowledge gaps that remain. Through a combination of a questionnaire and a literature review, we evaluated each question on the basis of 2 criteria: relevance and effort. We defined highly relevant questions as those that - if answered - would have the greatest impact on global biodiversity conservation and quantified effort based on the number of review publications addressing a particular question, which we used as a proxy for research effort. Using this approach, we identified a set of questions that, despite being perceived as highly relevant, have been the focus of relatively few review publications over the past 10 years. These questions covered a broad range of topics but predominantly tackled 3 major themes: conservation and management of freshwater ecosystems, role of societal structures in shaping interactions between people and the environment, and impacts of conservation interventions. We believe these questions represent important knowledge gaps that have received insufficient attention and may need to be prioritized in future research.

On the challenges of using field spectroscopy to measure the impact of soil type on leaf traits

David Coomes was supported by a grant from NERC (NE/K016377/1) and Matheus H. Nunes is supported by a PhD scholarship from the Conselho Nacional de Pesquisa e Desenvolvimento (CNPq).

Variação espaço-temporal da dinâmica da comunidade arbórea em fragmentos de floresta aluvial em Minas Gerais

Neste estudo, objetivou-se conhecer os padroes de dinâmica da comunidade de arvores em fragmentos florestais aluviais nos periodos de 2005-2007 e 2007-2009. Para isso, foi estudado um fragmento de floresta ciliar e cinco fragmentos de floresta aluvial, no interior da planicie de inundacao do rio Sapucai, em Sao Sebastiao da Bela Vista, MG, inventariados, inicialmente, em 2005 e avaliados novamente em 2007 e em 2009. Os resultados demonstraram padroes diferenciados entre os fragmentos e os periodos de tempo. Nos fragmentos onde foi observada, em estudos anteriores, maior influencia de enchentes e encharcamento do solo, a mortalidade de arvores foi maior no periodo de 2007-2009 do que no de 2005-2007. As taxas de mortalidade foram, de forma geral, maiores que as taxas de recrutamento, ocasionando a perda de individuos e a perda em area basal. Observando-se o historico da area, e possivel supor que essas perdas estao ocorrendo pela interacao de dois fatores: i) excesso hidrico apos uma grande enchente e ii) a ocorrencia de forte antropizacao, representado pelo corte seletivo e a entrada de bovinos no interior dos fragmentos.