Carbon fluxes and species diversity in grazed and fenced typical steppe grassland of Inner Mongolia, China

Abstract

Grasslands are dominant vegetation of China, support outstandingbiodiversity and sequester bulk amount of atmospheric CO2. Thesegrasslands are highly degraded and fragmented due to remarkableanthropogenic and grazing loads. Chinese Government has madegreat attempt to restore by grazing exclusion. The relations of carbonfluxes with species composition and diversity in the communitiessensitive to grazing by large herbivores are needed to be analysedunder the global climate change scenario. The objective of presentstudy was to comprehend the effects of grazing and fencing on theecosystem structure and function of the typical steppe grassland.MethodsTo meet the objectives, overgrazed and fenced (since year 2001) systemswere selected in typical steppe grassland at the DuolunRestoration Ecology Research Station, Inner Mogolia, China. Withineach system, three dominant communities with three replicateswere selected. In each replicate community, three 1 × 1 m plots,were randomly located. Each plot was divided into four 50 × 50 cmquadrats. A total of 216, 50 × 50 cm quadrats were sampled. Fromeach quadrat, number of individuals and above-ground herbaceousbiomass for each species, soil respiration (SR), ecosystem respiration(ER), net (NEE) as well as gross (GEE) ecosystem CO2 exchangeswere recorded in June 2015. Data were well analysed usingstatistical software. Canonical correspondence analysis showed differentialresponses of communities to the structure and function ofthe typical steppe grassland.Important FindingsAcross the communities, fencing reduced the soil temperatureby 12% and at the same time increased the soil moisture by44.30%, thus, increased the species richness by 28%, evenness by21%, above-ground biomass by 19% and plant carbon by 20%.Interestingly, fencing increased NEE by 128%, GEE by 77%, SR by65% and ER by 39%. Under fencing, species composition partiallygoverned the CO2 exchange processes.ConclusionsFencing reduces soil temperature and thereby improves speciesdiversity and more efficient CO2 sequestration and long-term andin-depth study is desirable for a better understanding of the relationshipbetween species diversity and ecosystem carbon uptake. © The Author(s) 2017. Published by Oxford University Press on behalf of the Institute of Botany, Chinese Academy of Sciences and the Botanical Society of China. All rights reserved.