Determinants of Caragana microphylla density distribution in the Mongolian steppe

作者：Narantsetseg Amartuvshin; Kang Sinkyu^*; Lkhamsuren Bolor Erdene; Ko Dongwook W

来源：Ecological Research, 2014, 29(5): 855-865.

DOI：10.1007/s11284-014-1173-y

• Shrub density
• Aridity
• Grazing
• Fire
• Tall grass

Regional differences in Caragana microphylla density in the Mongolian steppes were explained by considering multiple abiotic and biotic factors collectively, including aridity gradients, grazing regimes, fire disturbance, and interspecific interactions. In the central and eastern Mongolian steppes, we collected vegetation data from 127 sites. Along 250-m line transects, the hit frequencies of C. microphylla and tall-grass species were recorded. Ancillary data included weather information, livestock populations, fire occurrence maps, and herder camp locations. Based on the steppe types and disturbance regimes, the sites were classified into 12 sub-groups. The data were statistically analyzed at the site, county, and sub-group levels. The natural C. microphylla density decreased with climatic aridity from forb-steppes to semi-desert steppes, but this pattern was not observed at grazed and burned sites. Livestock grazing decreased C. microphylla density, but this effect was considerably confounded by aridity effects, especially in the central steppes, making the relationship between C. microphylla and livestock densities complex. Although fire appeared to be an important factor in the eastern steppes, the mechanism of its effect on C. microphylla density was unclear, because the fire-shrub interaction is influenced by the tall-grass recovery process after fire. Based on our results, we propose that two different confounding effects, namely aridity versus grazing and fire versus interspecific interactions, play important roles in determining the spatial distribution of C. microphylla density in the central and eastern Mongolian steppes, respectively.

• 出版日期2014-9