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2019

NEW PAPER: Soil Chemistry, and Not Short-term (1-2 year) Deer Exclusion, Explains Understory Plant Occupancy in Forests Affected by Acid Deposition
October 23, 2019
Danielle R Begley-Miller, Duane R Diefenbach, Marc E McDill, Patrick J Drohan, Christopher S Rosenberry, Emily H Just Domoto. In AoB PLANTS: The loss of species diversity and plant community structure throughout the temperate deciduous forests of North America have often been attributed to overbrowsing by white-tailed deer (Odocoileus virginanus). Slow species recovery following removal from browsing, or reduction in deer density, has been termed a legacy effect of past deer herbivory. However, vegetation legacy effects have also coincided with changes to soil chemistry throughout the north-eastern USA. In this paper, we assess the viability of soil chemistry (i.e. pH, extractable nutrients and extractable metals) and other factors (topography, light, overstory basal area and location) as alternative explanations for a lack of vegetation recovery. We compared the relative effects of soil chemistry, site conditions and short-term (1–2 year) deer exclusion on single-species occupancy probabilities of 10 plant taxa common to oak-hickory forests in central Pennsylvania. We found detection for all modelled species was constant and high (⁠p^ > 0.65), and occupancy probability of most taxa was best explained by at least one soil chemistry parameter. Specifically, ericaceous competing vegetation was more likely to occupy acidic (pH < 3.5), base cation-poor (K < 0.20 cmolc kg−1) sites, while deer-preferred plants were less likely to occur when soil manganese exceeded 0.1 cmolc kg−1. Short-term deer exclusion did not explain occupancy of any plant taxon, and site conditions were of nominal importance. This study demonstrates the importance of soil chemistry in shaping plant community composition in the north-central Appalachians, and suggests soil as an alternative, or additional, explanation for deer vegetation legacy effects. We suggest that the reliance on phyto-indicators of deer browsing effects may overestimate the effects of browsing if those species are also limited by unfavourable soil conditions. Future research should consider study designs that address the complexity of deer forest interactions, especially in areas with complex site-vegetation histories.
Lab Fulbright Scholar Jhony Benevides presents thesis work at Colombian Fulbright event
August 27, 2019
MS student Jhony Benevides was one of 4 Penn State Fulbright Scholars affiliated with the Cacao for Peace program to present at a Colombian Fulbright sponsored Cátedra in Monteria, Colombia.
NEW PAPER: A GLOBAL PERSPECTIVE ON THE HISTORY OF PHOSPHORUS MANAGEMENT DECISION SUPPORT APPROACHES IN AGRICULTURE: LESSONS LEARNED AND DIRECTIONS FOR THE FUTURE
July 15, 2019
Our new Journal of Environmental Quality paper on the the evolution of phosphorus (P) management decision support tools (DSTs) and systems (DSS) is out!
Cocoa, Colombia and Dogs
March 28, 2019
Canine team suelo helps advance cocoa research in Colombia
NEW BOOK CHAPTER: Backyard portals: A solutions-oriented approach to understanding and valuing soil.
March 11, 2019
Pennsylvania artist Stacy Levy and Penn State soil scientist Patrick Drohan teamed up to address the question...."How can we value nature through artistic and scientific methodologies?"...click to read more.
NEW PAPER: Geochemical and mineralogical characteristics of loess along northern Appalachian, USA major river systems appear driven by differences in meltwater source lithology
March 11, 2019
K.S. Lindeburg and P.J. Drohan: Eastern United States loess mapped by the U.S. Department of Agriculture, National Resources Conservation Service (USDA-NRCS) mostly occurs near major river systems like the Delaware and Susquehanna Rivers. Results suggest that developing a “loess fingerprint” for each river system based on major, minor and rare earth elements is possible, and likely to be useful in differentiating sources; however coarse silts may be a more effective fraction (than fine silts) for sediment sourcing, especially if rare earth elements are used.