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Do genetically-specific tree canopy environments feed back to affect genetically specific leaf decomposition rates?

LeRoy, Carri J., Fischer, Dylan G.
Plant and soil 2019 v.437 no.1-2 pp. 1-10
Populus fremontii, canopy, environmental factors, forest litter, genetics, genotype, leaves, microbial communities, models, phenology, spring, temperature, trees
AIMS: In forest ecosystems, trees may have genetically distinct patterns in leaf decomposition. Trees also can have genetically distinct canopy environments which modify temperature, moisture, and microbial communities on the forest floor. The interaction between these factors may result in underexplored interactions between microenvironment and leaf decomposition at the genotype level. METHODS: We compare litter decomposition rates for distinct genotypes of Fremont cottonwood (Populus fremontii) grown in a common garden environment under three different riparian conditions: 1) under a 16-tree stand of the same genotype, 2) under a 16-tree stand of another genotype, and 3) under a 16-tree stand of 16 different genotypes. Genotypes differed in canopy size and phenology. RESULTS: While genotype exerted a strong effect on decomposition, this effect was most pronounced when litter was decomposed under a self-similar (“home”) canopy. The strongest driver of decomposition rates across all factors (including litter quality and environmental factors) was spring (leaf-out) and fall (leaf-drop) phenology, but responses were variable by genotype. CONCLUSIONS: The influence of genetics on litter decomposition, canopy environment, and tree phenology provides justification for the inclusion of stand-level traits like canopy cover into models of decomposition and complicates the results of studies that rely on litter quality traits alone.