Variation in soil respiration under the tree canopy in a temperate mixed forest, central China, under different soil water conditions

Abstract

The forest canopy cover can directly and indirectly affect soil conditions and hence soil carbon emission through soil respiration. Little is known, however, on the effects of canopy cover on soil respiration under the canopy of different tree species and soil water conditions. We have examined the variation in soil respiration at different soil water conditions (dry <10 %, wet >20 %, v/v) under different tree canopy covers in comparison with the canopy interspace in a temperate coniferous (Pinus armandii Franch) and broadleaved (Quercus aliena var. acuteserrata) mixed forest in central China. The results show that soil respiration measured under tree canopy cover varied with canopy size and soil water content. Soil respiration under small‐sized canopies of P. armandii (PS) was higher than that under large‐sized (PL) canopies, but the difference was only significant under the dry soil condition. However, soil respiration under large‐sized canopies of Q. aliena (QL) was significantly greater than that under small‐sized (QS) canopies under both dry and wet soil conditions. The difference in soil respiration between differently sized canopies of Q. aliena (33.5–35.8 %) was significantly greater than that between differently sized canopies of P. armandii (2.4–8.1 %). Differences in soil respiration between inter‐plant gaps and under QS canopies in both the dry and wet soil conditions were significant. Significant increases in soil respiration (9.7–32.2 %) during the transition from dry to wet conditions were found regardless of canopy size, but the increase of soil respiration was significantly lower under P. armandii canopies (9.7–17.7 %) than under Q. aliena canopies (25.9–31.5 %). Our findings that the canopy cover of different tree species influences soil respiration under different soil moisture conditions could provide useful information for parameterizing and/or calibrating carbon flux models, especially for spatially explicit carbon models.

Trees modify the dynamics of soil CO2 efflux in coffee agroforestry systems

“…Generally, CO 2 efflux correlates positively with soil temperature and negatively with soil moisture (Davidson et al, 1998;Kosugi et al, 2007;Liu et al, 2013), as verified by our study (Fig. 4).…”

“…Increased canopy cover maintains soil moisture (Lin et al, 2006;Liu et al, 2013), as observed in our study (Fig. 2), due to a decrease in soil evaporation (Lin, 2010).…”

“…In the region, water availability is also important in January and February (rainy season), when short dry periods may occur leading to the bad formation of the coffee beans. Thus, agroforestry coffee systems may provide better conditions to retain the water in the system (Liu et al, 2013) and enhance coffee bean size (Vaast et al, 2006); therefore, decreasing the risk of economic losses from coffee production.…”

Effects of exotic guava (Psidium guajavaL.) invasion on soil properties in Limpopo, South Africa

“…For example, canopy shading and rainfall interception (especially for small rainfall events) could have caused the observed variation in soil moisture between the guava‐invaded sites and uninvaded sites. The above explanation is supported by observations by Shi et al () and Liu et al, () that canopy structure and size influence soil moisture and temperature. The high soil moisture content observed in guava‐invaded sites has a bearing on soil compaction, with invaded soils being less compact than uninvaded soils, although this was observed only in April and May.…”

“…The observed high soil moisture content in April and May underneath guava‐invaded sites as compared to uninvaded sites could be a result of several factors, for example the spatial distribution of individual trees (Luan, Liu, Zhu, Wang, & Liu, ), canopy cover (McCarthy & Brown, ), litter production (Reichstein et al, ) and variations in soil respiration (Liu et al, ). For example, canopy shading and rainfall interception (especially for small rainfall events) could have caused the observed variation in soil moisture between the guava‐invaded sites and uninvaded sites.…”