A Global Assessment of the State of Plant Health.

The Global Plant Health Assessment (GPHA) is a collective, volunteer-based effort to assemble expert opinions on plant health and disease impacts on ecosystem services based on published scientific evidence. The GPHA considers a range of forest, agricultural, and urban systems worldwide. These are referred to as (Ecoregion × Plant System), i.

Publisher Correction: Pervasive phosphorus limitation of tree species but not communities in tropical forests.

In this Letter, the y axis of the right-hand panel of Fig. 2a was mislabelled 'Phosphomonoesterase' instead of 'Phosphodiesterase'. This error has been corrected online.

Pervasive phosphorus limitation of tree species but not communities in tropical forests.

Phosphorus availability is widely assumed to limit primary productivity in tropical forests, but support for this paradigm is equivocal. Although biogeochemical theory predicts that phosphorus limitation should be prevalent on old, strongly weathered soils, experimental manipulations have failed to detect a consistent response to phosphorus addition in species-rich lowland tropical forests. Here we show, by quantifying the growth of 541 tropical tree species across a steep natural phosphorus gradient in Panama, that phosphorus limitation is widespread at the level of individual species and strengthens markedly below a threshold of two parts per million exchangeable soil phosphate.

Dynamics of two multi-stemmed understory shrubs in two temperate forests.

A multi-stemmed growth form may be an important trait enabling the persistence of individual shrubs in the forest understory. With the aim of evaluating the role of multiple stems, neighbor competition and soil nutrients in shrub performance, we study the dynamics of two temperate multi-stemmed shrub species. We modeled stem growth and survival of Corylus mandshurica and Acer barbinerve in two temperate forests with differing structure in northeastern China.

Leaf damage and density-dependent effects on six Inga species in a neotropical forest.

Many models have been proposed to explain the possible role of pests in the coexistence of a high diversity of plant species in tropical forests. Prominent among them is the Janzen-Connell model. This model suggests that specialized herbivores and pathogens limit tree recruitment as a function of their density or proximity to conspecifics.

Pests vs. drought as determinants of plant distribution along a tropical rainfall gradient.

Understanding the mechanisms that shape the distribution of organisms can help explain patterns of local and regional biodiversity and predict the susceptibility of communities to environmental change. In the species-rich tropics, a gradient in rainfall between wet evergreen and dry seasonal forests correlates with turnover of plant species. The strength of the dry season has previously been shown to correlate with species composition.

Allelochemic function for a primary metabolite: the case of l-tyrosine hyper-production in Inga umbellifera (Fabaceae).

Young leaves of tropical forest trees experience far higher herbivory pressure than mature leaves of the same species. Selection on young leaves has led to diverse forms of defense chemical expression. Though most allelochemicals are secondary metabolites, allelochemic function for a primary metabolite remains a possibility.

Contrasting mechanisms of secondary metabolite accumulation during leaf development in two tropical tree species with different leaf expansion strategies.

Young leaves of most species experience remarkably higher herbivore attack rates than mature leaves. Considerable theoretical effort has focused on predicting optimal defense and tradeoffs in defense allocation during leaf expansion. Among others, allocation to secondary chemistry may be dependent on growth constraints.