Precipitation drives interannual variation in summer soil respiration in a Mediterranean-climate, mixed-conifer forest

Abstract

Predictions of future climate change rely on models of how both environmental conditions and disturbance impact carbon cycling at various temporal and spatial scales. Few multi-year studies, however, have examined how carbon efflux is affected by the interaction of disturbance and interannual climate variation. We measured daytime soil respiration (R s ) over five summers (June-September) in a Sierra Nevada mixed-conifer forest on undisturbed plots and plots manipulated with thinning, burning and their combination. We compared mean summer R s by year with seasonal precipitation. On undisturbed plots we found that winter precipitation (PPT w ) explained between 77-96% of interannual variability in summer R s . In contrast, spring and summer precipitation had no significant effect on summer R s . PPT w is an important influence on summer R s in the Sierra Nevada because over 80% of annual precipitation falls as snow between October and April, thus greatly influencing the soil water conditions during the following growing season. Thinning and burning disrupted the relationship between PPT w and R s , possibly because of significant increases in soil moisture and temperature as tree density and canopy 110 Climatic Change (2009) 92:109-122 cover decreased. Our findings suggest that R s in some moisture-limited ecosystems may be significantly influenced by annual snowpack and that management practices which reduce tree densities and soil moisture stress may offset, at least temporarily, the effect of predicted decreases in Sierran snowpack on R s .

Precipitation frequency controls interannual variation of soil respiration by affecting soil moisture in a subtropical forest plantation

“…The two large variations of annual R S were both ascribed to changes in SWC. Large interannual variations of R S were also observed in a beech forest (Epron et al 2004), broadleaf forests (Martin and Bolstad 2005), and a Mediterranean forest (Asensio et al 2007;Concilio et al 2009). R S in a humid year was twice as high as in a dry year in a Mediterranean holm oak forest (Asensio et al 2007).…”

“…The changes of annual mean SWC can be influenced by precipitation and ET. Variation in precipitation amount usually explains interannual variability in SWC, which subsequently influences annual R S as in a temperate forest (Borken et al 1999(Borken et al , 2006, within seasonally dry biomes (savannas, shrublands, and deserts) (Raich et al 2002), in a Hesse forest (Epron et al 2004), and a Mediterranean forest (Concilio et al 2009). However, in this study, we found that SWC had no relation with precipitation amount but had a tight relation with rainfall frequency (Fig.…”

“…It has been investigated in some forests, including in semi-arid (Irvine and Law 2002), subhumid (Asensio et al 2007), and humid regions (e.g., Savage and Davidson 2001;Epron et al 2004;Concilio et al 2009), as well as on a global scale (Raich et al 2002). The interannual variation of R S is attributed to changes of biotic (Irvine et al 2007(Irvine et al , 2008 and abiotic (Irvine and Law 2002;Epron et al 2004) variables that usually exhibit year-to-year variation.…”

“…Second, changes of abiotic variables (e.g., temperature, moisture, and precipitation) may also cause variation of annual R S (Martin and Bolstad 2005). At a global scale, interannual variability of R S was found to be affected by temperature (Raich et al 2002) and precipitation (Chen et al 2010), whereas at an ecosystem scale, the variation of annual R S has generally been ascribed to changes in T S (Falk et al 2005;Phillips et al 2010), water availability (Savage and Davidson 2001;Borken et al 2002;Martin and Bolstad 2005), annual and seasonal rainfall amount (Asensio et al 2007;Concilio et al 2009), and precipitation regime (Harper et al 2005) in dry regions. Under humid conditions, however, interannual variation of R S was reported to be low in a cool-temperate forest (Mo et al 2005) and a boreal mixed forest (Savage and Davidson 2001), and the effect of precipitation variation was usually negligible.…”

Impact of Climate Change on Vegetation Growth in Arid Northwest of China from 1982 to 2011

“…Ecosystems in arid and semi-arid regions are sensitive to changes in climate [1][2][3][4][5]. Recently, a significant increase in vegetation growth and a change in climate have been observed in Xinjiang, a typical arid and semi-arid ecosystem located in Northwest China [6][7][8][9][10].…”