The InVEST hydrologic models were designed to represent the dominant processes of sediment/nutrient delivery and retention by land use/ land cover (LULC). Since they are not standard rainfall-runoff models, classical calibration and testing methods are not always applicable. Testing and calibration were particularly difficult in our study region due to: i) the absence of local data (e.g. in-str...

South Chilean forest ecosystems represent one of the largest areas of old-growth temperate rainforests remaining in the Southern hemisphere and have a high ecological value, but suffer from deforestation, invasion by exotic species, fragmentation, and increasing atmospheric nitrogen (N) deposition. To support sustainable forest management, more knowledge is required on nutrient cycling of these...

Biogeochemical properties, including nutrient concentrations, carbon gas fluxes, microbial biomass, and hydrolytic enzyme activities, were determined along a strong nutrient gradient in an ombrotrophic peatland in the Republic of Panama. Total phosphorus in surface peat decreased markedly along a 2.7 km transect from the marginal Raphia taedigera swamp to the interior sawgrass swamp, with simil...

We carried out 2 experimental simulations in which natural planktonic communities were subjected to a combination of turbulence and variable nutrient forcing. Nutrient addition was varied both in terms of total nutrient load and in the balance of elements. Unbalanced nutrient inputs (with regard to Redfield values) and varying nitrogen sources are frequent in coastal areas heavily exposed to hu...

Since this discovery, a number of studies have looked at improving the catalytic effects and understanding the role of additives in H2 cycling. However, the mechanism by which NaAlH4 is activated in the presence of a small amount of a transition metal is still not well understood. One of the principle questions is “How do the Al atoms migrate the long distances required during the hydrogenation...

76 The theme for the 142nd annual meeting of the American Fisheries Society (AFS) was “Fisheries Networks: Building Ecological, Social, and Professional Relationships,” and that provided me a hook to reflect on how studies of ecological networks have developed and how they can be used to inform fisheries research. Ecological networks, as we know them, date back to the pioneering studies of Raym...

Although the effects of nutrient enrichment on consumer-resource dynamics are relatively well studied in ecosystems based on living plants, little is known about the manner in which enrichment influences the dynamics and productivity of consumers and resources in detritus-based ecosystems. Because nutrients can stimulate loss of carbon at the base of detrital food webs, effects on higher consum...

BACKGROUND AND AIMS Simple models of herbaceous plant growth based on optimal partitioning theory predict, at steady state, an isometric relationship between shoot and root biomass during plant ontogeny, i.e. a constant root-shoot ratio. This prediction has received mixed empirical support, suggesting either that optimal partitioning is too coarse an assumption to model plant biomass allocation...

Nutrient limitation to net primary production (NPP) displays a diversity of patterns as ecosystems develop over a range of timescales. For example, some ecosystems transition from N limitation on young soils to P limitation on geologically old soils, whereas others appear to remain N limited. Under what conditions should N limitation and P limitation prevail? When do transitions between N and P...

Atrazine, metolachlor, carbaryl, and chlorothalonil are detected in streams throughout the U.S. at concentrations that may have adverse effects on benthic microbes. Sediment samples were exposed to these pesticides to quantify responses of ammonium, nitrate, and phosphate uptake by the benthic microbial community. Control uptake rates of sediments had net remineralization of nitrate (-1.58 NO3 ...