Tree Diversity, Site Index, and Carbon Storage Decrease With Aridity in Douglas-Fir Forests in Western Canada

Frontiers in Forests and Global Change

Teresa L. Ryan¹  Winnifred Jean Roach¹  Suzanne W. Simard¹  Camille E. Defrenne²  Les M. Lavkulich³  Brian J. Pickles⁴ 

[1] Department of Forest and Conservation Sciences, University of British Columbia, Vancouver, BC, Canada;Division of Environmental Sciences, Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, TN, United States;Faculty of Land and Food Systems, University of British Columbia, Vancouver, BC, Canada;School of Biological Sciences, Whiteknights, University of Reading, Reading, United Kingdom;

关键词: biodiversity;    carbon storage;    climate change;    Douglas-fir;    productivity;    site index;   

DOI  :  10.3389/ffgc.2021.682076

来源: DOAJ

【 摘 要 】

Forests are important for biodiversity, timber production and carbon accumulation, but these ecosystem services may be impacted by climate change. Field data collected from individual forest types occurring across a climatic gradient can contribute to forecasting these consequences. We examined how changes in temperature, precipitation and aridity affect ecosystem services in 23 mature Douglas-fir (Pseudotsuga menziesii) forests in nine climatic regions across a 900 km gradient in British Columbia, Canada. Using Canadian National Forest Inventory methodology, we assessed richness and diversity of plant functional groups, site index, and above- and below-ground carbon stocks. As aridity increased, ecosystem-level tree species richness declined on average from four to one species, Douglas-fir site index declined from 30 to 15 m, and ecosystem carbon storage decreased from 565 to 222 Mg ha–1. Tree species richness was positively and herb species richness negatively correlated with carbon storage. Carbon storage by ecosystem compartment was largest in aboveground live tree biomass, declining in the following order: mineral soils > coarse woody debris and dead standing trees > forest floor > small and fine woody debris > understory plants. Mineral soil carbon at depths of 0-15 cm, 15-35 cm, and 35-55 cm increased with increasing mean annual precipitation and decreasing aridity. Our results indicate that as aridity increases and precipitation decreases, tree species richness, site index and carbon storage in existing Douglas-fir forests declines. However, assisted or natural migration of Douglas-fir into more humid regions could be associated with more diverse, productive, carbon-rich forests. This study informs carbon stock vulnerability and provides empirical data essential for carbon stock forecasts.

【 授权许可】

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