Articles | Volume 6, issue 3
Solid Earth, 6, 799–810, 2015
Solid Earth, 6, 799–810, 2015

Research article 02 Jul 2015

Research article | 02 Jul 2015

Vegetation in karst terrain of southwestern China allocates more biomass to roots

J. Ni1,2, D. H. Luo3, J. Xia4, Z. H. Zhang5,6, and G. Hu5,6 J. Ni et al.
  • 1State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, China
  • 2Puding Karst Ecosystem Observation and Research Station, Chinese Academy of Sciences, Puding, China
  • 3Guizhou Development and Reform Commission, Guiyang, China
  • 4Guizhou Forestry Inventory and Planning Institute, Guiyang, China
  • 5School of Environment and Life Science, Guangxi Teachers Education University, Nanning, China
  • 6Key Laboratory of Beibu Gulf Environment Change and Resources Utilization of Ministry of Education, Guangxi Teachers Education University, Nanning, China

Abstract. In mountainous areas of southwestern China, especially Guizhou province, continuous, broadly distributed karst landscapes with harsh and fragile habitats often lead to land degradation. Research indicates that vegetation located in karst terrains has low aboveground biomass and land degradation that reduces vegetation biomass, but belowground biomass measurements are rarely reported. Using the soil pit method, we investigated the root biomass of karst vegetation in five land cover types: grassland, grass–scrub tussock, thorn–scrub shrubland, scrub–tree forest, and mixed evergreen and deciduous forest in Maolan, southern Guizhou province, growing in two different soil-rich and rock-dominated habitats. The results show that roots in karst vegetation, especially the coarse roots, and roots in rocky habitats are mostly distributed in the topsoil layers (89 % on the surface up to 20 cm depth). The total root biomass in all habitats of all vegetation degradation periods is 18.77 Mg ha−1, in which roots in rocky habitat have higher biomass than in earthy habitat, and coarse root biomass is larger than medium and fine root biomass. The root biomass of mixed evergreen and deciduous forest in karst habitat (35.83 Mg ha−1) is not greater than that of most typical, non-karst evergreen broad-leaved forests in subtropical regions of China, but the ratio of root to aboveground biomass in karst forest (0.37) is significantly greater than the mean ratio (0.26 ± 0.07) of subtropical evergreen forests. Vegetation restoration in degraded karst terrain will significantly increase the belowground carbon stock, forming a potential regional carbon sink.

Short summary
The root biomass study of karst (limestone and dolomite) vegetation in southwestern China and even in the word’s karst regions is rarely investigated. The mixed evergreen and deciduous broadleaved forest in karst terrain of SW China has higher root biomass, but very high ratio of root to aboveground biomass compared to non-karst subtropical evergreen broadleaved forests. Such findings have significant ecological meanings for vegetation restoration and carbon increment.