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Mortality and community changes drive sudden oak death impacts on litterfall and soil nitrogen cycling
Author(s) -
Cobb Richard C.,
Eviner Valerie T.,
Rizzo David M.
Publication year - 2013
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.12370
Subject(s) - plant litter , ecosystem , ecology , litter , cycling , bay , forest ecology , nutrient cycle , biogeochemical cycle , biology , environmental science , geography , forestry , archaeology
Summary Few studies have quantified pathogen impacts to ecosystem processes, despite the fact that pathogens cause or contribute to regional‐scale tree mortality. We measured litterfall mass, litterfall chemistry, and soil nitrogen ( N ) cycling associated with multiple hosts along a gradient of mortality caused by P hytophthora ramorum , the cause of sudden oak death. In redwood forests, the epidemiological and ecological characteristics of the major overstory species determine disease patterns and the magnitude and nature of ecosystem change. Bay laurel ( U mbellularia californica ) has high litterfall N (0.992%), greater soil extractable NO 3 – N , and transmits infection without suffering mortality. Tanoak ( N otholithocarpus densiflorus ) has moderate litterfall N (0.723%) and transmits infection while suffering extensive mortality that leads to higher extractable soil NO 3 – N . Redwood ( S equoia sempervirens ) has relatively low litterfall N (0.519%), does not suffer mortality or transmit the pathogen, but dominates forest biomass. The strongest impact of pathogen‐caused mortality was the potential shift in species composition, which will alter litterfall chemistry, patterns and dynamics of litterfall mass, and increase soil NO 3 – N availability. Patterns of P . ramorum spread and consequent mortality are closely associated with bay laurel abundances, suggesting this species will drive both disease emergence and subsequent ecosystem function.