Soil Shear Strength Losses In Two Fresh Marshes With Variable Increases In N And P Loading

We measured soil shear strength (SSS) from 2009 to 2018 in two hydrologically distinct freshwater marshes dominated by Panicum hemitomon after nitrogen (N) and phosphorous (P) were applied to the surface in spring. The SSS averaged over 100-cm depth in the floating and anchored marshes declined up to 30% throughout the profiles and with no apparent differences in the effects of the low, medium, and high N + P dosing. Plots with only N or P additions exhibited significant changes in SSS at individual depths below 40 cm for the anchored marsh, but not the floating marsh. The average SSS for the anchored marsh over the entire 100 cm profile declined when N and P were added separately or together. At the floating marsh, however, the SSS decreased when N and P were added in combination, or P alone, but not for the N addition. Increasing nutrient availability to these freshwater marsh soils makes them weaker, and perhaps lost if eroded or uplifted by buoyant forces during storms. These results are consistent with results from multi-year experiments demonstrating higher decomposition rates, greenhouse gas emissions, and carbon losses in wetlands following increased nutrient availability

The Effects Of N, P And Crude Oil On The Decomposition Of Spartina Alterniflora Belowground Biomass

We conducted a laboratory experiment to examine how the decomposition of particulate belowground organic matter from a salt marsh is enhanced, or not, by different mixtures of crude oil, nitrogen (N), or phosphorus (P) acting individually or synergistically. The experiment was conducted in 3.8 L sampling chambers producing varying quantities of gas whose volume was used as a surrogate measure of organic decomposition under anaerobic conditions. Gas production after 28 days, from highest to lowest, was +NP = +N \u3e\u3e\u3e +P, or +oil. The gas production under either +P or +oil conditions was indistinguishable from gas production in the control chamber. Nitrogen, not phosphorus, or +NP, was the dominant factor controlling organic decomposition rates in these experiments. The implication for organic salt marsh soils is that shoreline erosion is enhanced by salt marsh oiling, presumably by its toxicity, but not by its effect on the decomposition rates of plant biomass belowground. Nutrient additions, on the other hand, may compromise the soil strength, creating a stronger disparity in soil strength between upper and lower soil layers leading to marsh loss. Nutrient amendments intended to decrease oil concentration in the marsh may not have the desired effect, and are likely to decrease soil strength, thereby enhancing marsh-to-water conversions in organic salt marsh soils

Climate, Ticks and Disease

This book brings together expert opinions from scientists to consider the evidence for climate change and its impacts on ticks and tick-borne infections. It considers what is meant by 'climate change', how effective climate models are in relation to ecosystems, and provides predictions for changes in climate at global, regional and local scales relevant for ticks and tick-borne infections. It examines changes to tick distribution and the evidence that climate change is responsible. The effect of climate on the physiology and behaviour of ticks is stressed, including potentially critical impacts on the tick microbiome. Given that the notoriety of ticks derives from pathogens they transmit, the book considers whether changes in climate affect vector capacity. Ticks transmit a remarkable range of micro- and macro-parasites many of which are pathogens of humans and domesticated animals. The intimacy between a tick-borne agent and a tick vector means that any impacts of climate on a tick vector will impact tick-borne pathogens. Most obviously, such impacts will be apparent as changes in disease incidence and prevalence. The evidence that climate change is affecting diseases caused by tick-borne pathogens is considered, along with the potential to make robust predictions of future events. This book contains: Expert opinions and predictions. Global coverage of trends in ticks and disease. In-depth examination of climate change and tick distribution links.This book is suitable for researchers and students studying zoology, biological sciences, medical entomology, animal health, veterinary medicine, epidemiology, parasitology, and climate change impacts; and for those concerned with public health planning or livestock management where ticks and tick-borne pathogens pose a threat