Effects of Plant Functional Group Removal on Microbial Substrate Metabolic Function and Soil Respiration in Subtropical Eucalyptus Plantations

Since aboveground communities and belowground communities are intimately linked and these linkages greatly affect ecosystem properties, removal of plant functional groups from aboveground communities will exert a great impact on belowground communities. Based on the previous works that found plant functional group removal greatly altered soil microbial community composition and litter decomposition rate (Wu and Liu et al., 2011. Functional Ecology 25: 921-931.), Associate professor LIU Zhanfeng and PhD student WU Jianping from Restoration Ecology Research Group led by professor Fu shenglei at South China Botanical Garden CAS, further investigated the effects of understory removal and tree girdling on microbial substrate metabolic function and soil respiration in two subtropical Eucalyptus plantations. The results showed that: (1) Tree girdling significantly altered the substrate metabolic pattern of soil culturable bacteria, but not for understory removal (Figure 1); (2) The effects of plant function group removal on microbial substrate metabolic function were highly seasonally dependent and microbial substrate metabolic pattern was mainly affected by sampling season and seasonal variation of soil microclimate (Figure 1); (3) Understory plants can make substantial contributions to soil respiration, and understory root respiration accounted for 16-29.5% of total soil root respiration in 2-year-old Eucalyptus plantation, and 10.9-36.3% of total soil root respiration in 24-year-old Eucalyptus plantation (Figure 2).

This study provided direct experimental evidences that understory vegetation plays an important ecological role in subtropical Eucalyptus plantation. This study also highlighted that more attentions should be paid on understory vegetation in the future forest ecology research. These works have been published in Soil Biology and Biochemistry (Wu and Liu et al., 2011. 43: 2355-2357), Applied Soil Ecology (Liu et al., 2012. 54:7-13) and Pedobiologia (Liu et al., 2012. 55: 7-13), the leading international journals in soil science field.