The chemical ecology of tropical forest diversity: Environmental variation, chemical similarity, herbivory, and richness.

Species richness in tropical forests is correlated with other dimensions of diversity, including the diversity of plant-herbivore interactions and the phytochemical diversity that influences those interactions. Understanding the complexity of plant chemistry and the importance of phytochemical diversity for plant-insect interactions and overall forest richness has been enhanced significantly by the application of metabolomics to natural systems. The present work used proton nuclear magnetic resonance spectroscopy ( H-NMR) profiling of crude leaf extracts to study phytochemical similarity and diversity among Piper plants growing naturally in the Atlantic Rainforest of Brazil.

Terpenoid profiles of resin in the genus Dracaena are species specific.

Dragon's blood is the colloquial name for the red resin produced by tree species in the genus Dracaena (Asparagaceae), and the resin is directly involved in plant defensive mechanisms against pathogen and herbivore attack. It is also widely used in traditional folk medicine due to its antiviral, antimicrobial and antitumor activities. In the present work, a method using solid phase microextraction combined with two-dimensional gas chromatography with time-of-flight mass spectrometric detection was developed for the analysis of resin from five Dracaena species, namely Dracaena cinnabari Balf.

Early recruitment responses to interactions between frequent fires, nutrients, and herbivory in the southern Amazon.

Understanding tropical forest diversity is a long-standing challenge in ecology. With global change, it has become increasingly important to understand how anthropogenic and natural factors interact to determine diversity. Anthropogenic increases in fire frequency are among the global change variables affecting forest diversity and functioning, and seasonally dry forest of the southern Amazon is among the ecosystems most affected by such pressures.

An optimal defense strategy for phenolic glycoside production in Populus trichocarpa--isotope labeling demonstrates secondary metabolite production in growing leaves.

Large amounts of carbon are required for plant growth, but young, growing tissues often also have high concentrations of defensive secondary metabolites. Plants' capacity to allocate resources to growth and defense is addressed by the growth-differentiation balance hypothesis and the optimal defense hypothesis, which make contrasting predictions. Isotope labeling can demonstrate whether defense compounds are synthesized from stored or newly fixed carbon, allowing a detailed examination of these hypotheses.

Costs of defense and a test of the carbon-nutrient balance and growth-differentiation balance hypotheses for two co-occurring classes of plant defense.

One of the goals of chemical ecology is to assess costs of plant defenses. Intraspecific trade-offs between growth and defense are traditionally viewed in the context of the carbon-nutrient balance hypothesis (CNBH) and the growth-differentiation balance hypothesis (GDBH). Broadly, these hypotheses suggest that growth is limited by deficiencies in carbon or nitrogen while rates of photosynthesis remain unchanged, and the subsequent reduced growth results in the more abundant resource being invested in increased defense (mass-balance based allocation).

Interactions between repeated fire, nutrients, and insect herbivores affect the recovery of diversity in the southern Amazon.

Surface fires burn extensive areas of tropical forests each year, altering resource availability, biotic interactions, and, ultimately, plant diversity. In transitional forest between the Brazilian cerrado (savanna) and high stature Amazon forest, we took advantage of a long-term fire experiment to establish a factorial study of the interactions between fire, nutrient availability, and herbivory on early plant regeneration. Overall, five annual burns reduced the number and diversity of regenerating stems.

Ontogenetic differences of herbivory on woody and herbaceous plants: a meta-analysis demonstrating unique effects of herbivory on the young and the old, the slow and the fast.

The effect of herbivory on plant performance is the subject of a large number of ecological studies, and plant responses to herbivory range from reduced reproduction to overcompensation. Because plant defenses, stored resources, and allocation demands change throughout a plant's lifetime, it can be hypothesized the effects of herbivory also vary with development. The present work extends previous analyses to incorporate hundreds of studies in a new meta-analysis addressing this topic.