Condo or cuisine? The function of fine woody debris in driving decomposition, detritivores, and their predators.

Community structure and ecosystem function may be driven by the size or the energy within a given habitat, but these metrics (space and energy) are difficult to separate, especially in systems where the habitat itself is also food, such as detritus. Only a handful of studies have attempted to isolate potential mechanisms experimentally, which has left a notable knowledge gap in understanding the drivers of community structure and function. Here, we tested whether fine woody debris (FWD) affects leaf litter communities primarily as a source of space or energy.

Sodium as a subsidy in the spring: evidence for a phenology of sodium limitation.

Understanding the factors that mediate carbon (C) cycling is increasingly important as anthropogenic activities and climate change alter ecosystems. Decomposition rates mediate C cycling and are in part regulated by sodium (Na) where Na is limiting up to some threshold after which Na becomes stressful and reduces decomposition rates (i.e.

Termite Presence and Feeding on Loblolly Pine Wood Differs Among Four Root-Infecting Bluestain (ophiostomatoid) Fungal Species.

Bark beetles and root weevils can impact forests through tree death on landscape scales. Recently, subterranean termites have been linked to these beetles via the presence of bluestain fungi (Ascomycota: Ophiostomataceae), which are vectored to trees by beetles. However, only a small subset of bluestain species have been examined.

The geography of grassland plant chemistry and productivity accounts for ant sodium and sugar usage.

In Focus: Kaspari, M., Welti, E. A.

Multiple riparian-stream connections are predicted to change in response to salinization.

Secondary freshwater salinization, a common anthropogenic alteration, has detrimental, lethal and sub-lethal effects on aquatic biota. Ions from secondary salinization can become toxic to terrestrial and aquatic organisms when exposed to salinized runoff that causes periodic high-concentration pulses. Gradual, low-level (less than 1000 ppm salinity) increases in salt concentrations are also commonly documented in regions with urbanization, agriculture, drilling and mining.

Indirect effects of bark beetle-generated dead wood on biogeochemical and decomposition processes in a pine forest.

Bark beetle outbreaks are increasing in frequency and intensity, generating massive inventories of dead trees globally. During attacks, trees are pre-inoculated with ophiostomatoid fungi via bark beetles, which has been shown to increase termite presence and feeding. These events may, in turn, alter biogeochemical cycles during decomposition.

Towards a geography of omnivory: Omnivores increase carnivory when sodium is limiting.

Towards understanding the geography of omnivory, we tested three hypotheses that predict the proportion of animal tissue consumed: the sodium limitation hypothesis predicts that omnivores increase animal consumption in Na-poor environments because Na bioaccumulates from plants to predators; thus, heterotrophs are Na-rich sources. The nitrogen limitation and habitat productivity hypotheses use the same logic to predict more animal consumption in N-poor and productive environments respectively. Omnivory is a common trophic strategy, but what determines the balance of plant and animal tissue omnivores consume is relatively unexplored.

Thermal adaptation and phosphorus shape thermal performance in an assemblage of rainforest ants.

We studied the Thermal Performance Curves (TPCs) of 87 species of rainforest ants and found support for both the Thermal Adaptation and Phosphorus-Tolerance hypotheses. TPCs relate a fitness proxy (here, worker speed) to environmental temperature. Thermal Adaptation posits that thermal generalists (ants with flatter, broader TPCs) are favored in the hotter, more variable tropical canopy compared to the cooler, less variable litter below.

Urine as an important source of sodium increases decomposition in an inland but not coastal tropical forest.

Nutrient pulses can profoundly impact ecosystem processes and urine is a frequently deposited source of N and K, and Na. Na is unimportant to plants, but its addition can increase decomposition and change invertebrate community structure in Na-poor tropical forests. Here we used synthetic urine to separate the effects of Na from urine's other nutrients and contrasted their roles in promoting decomposition and detritivore recruitment in both a Na-poor inland Ecuadorian and Na-rich coastal Panamanian tropical forest.

Thermal adaptation generates a diversity of thermal limits in a rainforest ant community.

The Thermal Adaptation Hypothesis posits that the warmer, aseasonal tropics generates populations with higher and narrower thermal limits. It has largely been tested among populations across latitudes. However, considerable thermal heterogeneity exists within ecosystems: across 31 trees in a Panama rainforest, surfaces exposed to sun were 8 °C warmer and varied more in temperature than surfaces in the litter below.

Sodium fertilization increases termites and enhances decomposition in an Amazonian forest.

Added Na was used to determine whether litter decomposition and associated fungal biomass and termites are limited by Na availability in a lowland tropical rainforest at Yasuni, Ecuador. This is a partial test of the "sodium ecosystem respiration" (SER) hypothesis that posits Na is critical for consumers but not plants, that Na shortfall is more likely on highly weathered soils inland from oceanic aerosols, and that this shortfall results in decreased decomposer activity. We fertilized 4 x 4 m plots twice a month for a year with quantities of Na comparable to those falling on a coastal tropical rainforest.

Sodium shortage as a constraint on the carbon cycle in an inland tropical rainforest.

Sodium (Na) is uncommon in plants but essential to the metabolism of plant consumers, both decomposers and herbivores. One consequence, previously unexplored, is that as Na supplies decrease (e.g.