Research On Species Diversity, Biomass And Carbon Storage Of Different Plantations In Guangxi Karst Area

Karst region in southwest of China is important ecological barrier. However, long-term irrational development in this area has led to serious rocky desertification. Consequently, rocky desertification control has become the national demand. In this present study, we developed several afforestation modes with legumes as rocky desertification control species, including A. fraxinifolius plantation monocultures, D. odorifera plantation monocultures, and mixed A. Jraxinifolius X D. odorifera plantations, in rocky desertification area of Mashan County, Guangxi Province to assess the effects of different plantations on the ecological function restoration in Karst rocky desertification area. Our results will provide theoretical basis for the comprehensive control of rocky desertification in southwest of China. The main results are as follows:(1) Afforestation with legumes in rocky desertification area can significantly increase species diversity in understory. Compared to the control (a typical shrub) adjacent to the plantations, the Margalef, Simpson, Shannon, Pielou evenness index in shrub layers of the three plantations was 1.17-1.50,1.67-2.03,1.71-1.97 and 1.65-2.05 times of the control (shrub). All the highest diversity indexes occurred in the mixed A. fraxinifoliusX D. odorifera plantations. In the herb layers, all the diversity indexes were higher in the mixed A. fraxinifolius X D. odorifera plantations without statistical significant difference with each other.(2) Afforestation with legumes in rocky desertification area can significantly increase ecosystem biomass accumulation and productivity. The ecosystem biomass in A. fraxinifolius plantations (17.83t/hm2), D. odorifera plantations (15.74t/hm2) and mixed A. fraxinifolius X D. odorifera plantations (17.05t/hm2) was significantly higher than that in the control (1.82t/hm2) and 8.65-9.80 times higher than the control. However, the differences of ecosystem biomass and productivity between the three plantations were not statistical significant.(3) Afforestation with legumes in rocky desertification area can significantly increase ecosystem carbon storage and biomass C sequestration ability. The ecosystem carbon stocks in A. fraxinifolius plantations (66.00tc/hm2), D. odorifera plantations (65.81tc/hm2) and mixed A. fraxinifolius XD. odorifera plantations (62.50tc/hm2) was significantly higher than that in the control (36.35t c/hm2) and 1.72-1.82 times higher than the control.. The ecosystem carbon sequestration rate in A. fraxinifolius plantations (16.50t c/hm2a), D. odorifera plantations (16.45tc/hm2 a) and mixed A. fraxinifolius X D. odorifera plantations (15.63tc/hm2a) was significantly higher than that in the control (36.35tc/hm2) and 1.72～1.82 times higher than the control. However, the differences of ecosystem biomass C sequestration rate between the three plantations were not statistical significant.(4) Afforestation with legume function groups, such as D. odorifera and A. fraxinifolius, is a practical measure to control rocky desertification and should be promoted and applied in Karst rocky desertification area in southern China.