The Initial Influence Of Different Thinning Intensity On Soil Organic Carbon In Low Efficiency Stands Of Cuprssus Funebris

In this paper,33a raw Cupressus funebris inefficient plantations act as the object in Jingyang district, Deyang city, Sichuan province; we set up five kinds of thinning treatment. They are weak degree of thinning (T1,15%), moderate thinning (T2,25%), thinning (T3,35%), very thinning (T4,50%) and a control (CK,0%), to study the effects of different thinning intensities of cedar plantations inefficiency of soil organic carbon and activated carbon. The main results were as follows.(1) Low efficiency stands of Cuprssus funebris after thinning la, four kinds of thinning intensity organic carbon storage in soil profile increased 1.56-18.23 MgC·hm-2. T4 organic carbon storage in soil profile was significantly higher than the other three kinds of thinning intensity (P<0.05); organic carbon storage in soil profile was significantly higher than T3, T2, T1 and CK (P<0.05). This indicated different thinning intensity increased soil carbon storage, which, T4 and T3 increased obviously.(2) Carbon dioxide (ROC), water-soluble carbon (WSOC) and microbial biomass carbon (SMBC) in low efficiency stands of Cuprssus funebris increased with the increase of the thinning intensity. Four kinds of thinning intensity SMBC increased 1.63-48.14 mgC ·kg-1 than CK; WSOC increased 2.53-37.13 mgC·kg-1 than CK; ROC than CK increased 0.05-0.66 gC·kg-1. SMBC, WSOC and ROC in T4 were obviously higher than the other three kinds of thinning intensity as well as CK (P<0.05); SMBC and WSOC in T3 were significantly higher than T2, T1 and CK; T2 and T1 were obviously higher than the ROC and CK. This indicated that the inefficient cedar forest soil active carbon content increased with the increase of the thinning intensity.(3) In this study, Cupressus funebris inefficient Plantation under 49 genera and 32 families of plants were recorded, a total of 7594 in 53 kinds. Shannon-Wiener index (H) and Simpson dominance index (C) were increased with the increasing of the thinning intensity which T4 and T3 were significantly increased (P<0.05). It suggested that, T4 and T3 were contributed to the increase of the plant diversity under low efficiency stands of Cuprssus funebris.(4) TOC, ROC, WSOC and SMBC in low efficiency stands of Cuprssus funebris showed a significant positive correlation (P<0.01); and various shrub diversity index showed a positive relationship, but not obvious; each with diverse understory herbaceous index showed a positive correlation among the Pielou index (Jsw) highly significant positive correlation (r> 0, P<0.01). This suggested that soil organic carbon and activated carbon intensity have a close relationship in different thinning intensity, and they increased with the increase in shrub and grass understory diversity.In summary, low efficiency stands of Cuprssus funebris after thinning 1a, the soil organic carbon, activated carbon and diversity of understory shrub and grass have increased. Four kinds of thinning intensity, increase the maximum volume of soil organic carbon storage T4 and each component of activated carbon, T3 were followed by it, T2 and T1 were obvious. Therefore, a certain thinning intensity in low efficiency stands of Cuprssus funebris could improve the strength of understory vegetation biodiversity, as well as increased the soil organic carbon storage and soil active carbon content, which was important to the enhancement of forest carbon sequestration, reducing atmospheric CO2, etc. Meanwhile, the results of the study showed that T4 and T3 were two more suitable thinning intensity transformations in low efficiency stands of Cuprssus funebris. And it could be generalized in the study area in low efficiency stands of Cuprssus funebris.