My name is Jeff Atkins and I am excited to be serving as a PLOS Ecology site editor along with Sasha and Jens. I am an ecosystem ecologist with a background in watershed biogeochemistry. My research primarily focuses on the interaction of vegetation heterogeneity and landscape position within complex terrain to affect carbon and water cycling.
In a mixed forest that contains different tree and understory plant species of varying ages, the result is a forest of varying horizontal and vertical structure. Some areas will have complete, canopy coverage, while other areas may be bare, forest gaps. How do these differences impact the forest micrometeorology–such as soil moisture or soil temperature? What happens when there is the further confounding issue of terrain complexity?
Water, of course, moves downhill. In mountainous areas this results in divergent areas of soil moisture along ridges that are drier, and convergent areas in valleys or mountain hollows that are much wetter.
An important scientific question is how do all of these landscape factors interact to exert controls on carbon cycling processes such as decomposition and soil respiration?
The watershed I have done the majority of my research in is located near Canaan Valley, West Virginia in the Allegheny Mountains of the United States. This area has cool summers and fairly cold winters. It is also quite wet, with average annual rainfall just above 1400 mm a year.
Before European settlement, the forests of the Canaan Valley were populated by towering canopies of red spruce and eastern hemlock. However, the area was heavily logged between 1880 and 1930 and subsequently impacted heavily by forest fires and human disturbance. The forest today is much different and is comprised mainly of red maple and yellow birch, with hemlock and spruce relegated to minor constituents along ridgelines. These forests also have a notable understory shrub component, primarily comprised of rhododendron (Rhododendron maximum).
Rhododendron is an evergreen shrub from the heath family (Ericaceae). While rhododendron is considered an invasive species in areas of Iceland and the United Kingdom, it is endemic to the mountains of West Virginia and much of the broader Appalachian range that extends up and down the east coast of the United States.
To assess the interaction of vegetation and landscape position, I measured surface soil carbon dioxide fluxes, soil moisture, and soil temperature, along with soil chemical and physical properties, across the watershed for three years. I found that soil carbon dioxide fluxes were higher beneath shrubs and at points of higher elevation in the watershed. The primary driver behind this pattern was soil moisture–areas higher in the watershed and beneath shrubs tended to be drier.
Soil temperature is the primary driver of surface soil carbon dioxide fluxes—as temperatures increase, fluxes are higher. Soil moisture however, serves an important secondary role. At high values of soil moisture, the pore spaces inside the soil matrix are full of water. This limits transport of carbon dioxide to the surface. At low values of soil moisture, the production of carbon dioxide in the soil is decreased—either through declines in root respiration from plants or via effects on the soil microbial community. At medium values of soil moisture there is what has been termed a “production optimality” where peak fluxes of surface soil carbon dioxide fluxes occur.
One of the more interesting drivers of the dynamics of carbon cycling I have seen in my research is the influence of inter-annual climate variability. Yearly rainfall ranged from 1042 to 1739 mm during my study period. In my really wet year, 2011, I saw fluxes decrease across the landscape, but in 2010, the driest year, fluxes were higher and the effects of vegetation and elevation were exacerbated. When the soils dried, fluxes beneath shrubs were much higher. Areas higher in the watershed also showed higher fluxes. These findings have furthered my interest in how global climate change is driving inter-annual climate dynamics and affecting ecosystems. I am also interested in the influence of forest structure and how that drives ecosystem processes.
I have a strong interest in science communication and open science and I look forward to what the PLOS Ecology community can become. I am excited to write about ecology related articles and to help shine a light on brilliant scientists as well as talented writers in the wider ecology and science blogosphere. Thanks for reading a bit about my research. You can learn more here and you will also see more of my work on this website in the future. You may also follow me on Twitter (@atkinsjeff) where you will see me tweet mostly about ecology, hydrology, open science, baseball, and loud music.