Abstract: The future of tropical managed forests is threatened by climate change. In anticipation of the increase in the frequency of drought episodes predicted by climatic models for intertropical regions, it is essential to study commercial trees' resilience and vulnerability to water stress by identifying potential interaction effects between selective logging and stress due to a lack of water. Focusing on 14 species representing a potential or acknowledged commercial interest for wood production in the Guiana Shield, a joint model coupling growth and mortality for each species was parametrized, including a climatic variable related to water stress and the quantity of aboveground biomass lost after logging. For the vast majority of the species, water stress had a negative impact on growth rate, while the impact of logging was positive. The opposite results were observed for the mortality. Combining results from growth and mortality models, we generate vulnerability profiles and ranking from species apparently quite resistant to water stress (Chrysophyllum spp., Goupia glabra Aubl., Qualea rosea Aubl.), even under logging pressure, to highly vulnerable species (Sterculia spp.). In light of our results, forest managers in the Guiana Shield may want to conduct (i) a conservation strategy of the most vulnerable species and (ii) a diversification of the logged species. Conservation of the already-adapted species may also be considered as the most certain way to protect the tropical forests under future climates. © 2016 by the authors.

Abstract: Understanding how plants are constructed; i.e., how key size dimensions and the amount of mass invested in different tissues varies among individuals; is essential for modeling plant growth, estimating carbon stocks, and mapping energy fluxes in the terrestrial biosphere. Allocation patterns can differ through ontogeny, but also among coexisting species and among species adapted to different environments. While a variety of models dealing with biomass allocation exist, we lack a synthetic understanding of the underlying processes. This is partly due to the lack of suitable data sets for validating and parameterizing models. To that end, we present the Biomass and allometry database (BAAD) for woody plants. The BAAD contains 259 634 measurements collected in 176 different studies, from 21 084 individuals across 678 species. Most of these data come from existing publications. However, raw data were rarely made public at time of publication. Thus the BAAD contains individual level data from different studies, transformed into standard units and variable names. The transformations were achieved using a common workflow for all raw data files. Other features that distinguish the BAAD are: (i) measurements were for individual plants rather than stand averages; (ii) individuals spanning a range of sizes were measured; (iii) inclusion of plants from 0.01-100 m in height; and (iii) biomass was estimated directly, i.e., not indirectly via allometric equations (except in very large trees where biomass was estimated from detailed subsampling). We included both wild and artificially grown plants. The data set contains the following size metrics: total leaf area; area of stem crosssection including sapwood, heartwood, and bark; height of plant and crown base, crown area, and surface area; and the dry mass of leaf, stem, branches, sapwood, heartwood, bark, coarse roots, and fine root tissues. We also report other properties of individuals (age, leaf size, leaf mass per area, wood density, nitrogen content of leaves and wood), as well as information about the growing environment (location, light, experimental treatment, vegetation type) where available. It is our hope that making these data available will improve our ability to understand plant growth, ecosystem dynamics, and carbon cycling in the world's vegetation.

Abstract: This study focuses on the importance in hyperdiverse regions, such as the Amazonian forest, of accelerating and optimising the census of invertebrate communities.
We carried out low-intensity sampling of tropical moth (Lepidoptera) assemblages in disturbed forest fragments in Brazil.
We combined DNA barcoding and taxonomists’ expertise to produce fast and accurate surveys of local diversity, including the recognition and census of undescribed and endemic species.
Integrating expert knowledge of species distributions, we show that despite limited sampling effort, our approach revealed an unexpectedly high number of new and endemic species in severely threatened tropical forest fragments.
These results highlight the risk of silent centinelan extinctions and emphasise the urgent need for accelerated invertebrate surveys in high-endemism and human-impacted tropical forests.

Abstract: The Neotropical understory plant Tachia guianensis (Gentianaceae)- known to shelter the colonies of several ant species in its hollow trunks and branches-does not provide them with food rewards (e.g., extrafloral nectar). We tested whether these ants are opportunistic nesters or whether mutualistic relationships exist as for myrmecophytes or plants sheltering ant colonies in specialized hollow structures in exchange for protection from enemies and/or nutrient provisioning (myrmecotrophy). We noted 37 ant species sheltering inside T. guianensis internodes, three of them accounting for 43.5% of the cases. They protect their host plants from leaf-cutting ant defoliation and termite damage because individuals devoid of associated ants suffered significantly more attacks. Using the stable isotope 15N, we experimentally showed that the tested ant species furnish their host plants with nutrients. Therefore, a mutualism exists. However, because it is associated with numerous ant species, T. guianensis can be considered a nonspecialized myrmecophyte. © 2017 by The University of Chicago.

Abstract: BackgroundMore than a half century ago, Shinozaki et al. (Shinozaki K, Yoda K, Hozumi K, Kira T. 1964a. A quantitative analysis of plant form – the pipe model theory. I. Basic analyses. Japanese Journal of Ecology B: 97–105) proposed an elegant conceptual framework, the pipe model theory (PMT), to interpret the observed linear relationship between the amount of stem tissue and corresponding supported leaves. The PMT brought a satisfactory answer to two vividly debated problems that were unresolved at the moment of its publication: (1) What determines tree form and which rules drive biomass allocation to the foliar versus stem compartments in plants? (2) How can foliar area or mass in an individual plant, in a stand or at even larger scales be estimated? Since its initial formulation, the PMT has been reinterpreted and used in applications, and has undoubtedly become an important milestone in the mathematical interpretation of plant form and functioning.ScopeThis article aims to review the PMT by going back to its initial formulation, stating its explicit and implicit properties and discussing them in the light of current biological knowledge and experimental evidence in order to identify the validity and range of applicability of the theory. We also discuss the use of the theory in tree biomechanics and hydraulics as well as in functional–structural plant modelling.ConclusionsScrutinizing the PMT in the light of modern biological knowledge revealed that most of its properties are not valid as a general rule. The hydraulic framework derived from the PMT has attracted much more attention than its mechanical counterpart and implies that only the conductive portion of a stem cross-section should be proportional to the supported foliage amount rather than the whole of it. The facts that this conductive portion is experimentally difficult to measure and varies with environmental conditions and tree ontogeny might cause the commonly reported non-linear relationships between foliage and stem metrics. Nevertheless, the PMT can still be considered as a portfolio of properties providing a unified framework to integrate and analyse functional–structural relationships.