Karst landscapes constitute approximately 12–15% of the global terrestrial surface. Large areas of karst lands may have rock outcrop proportions greater than 30% (which is the lower criterion of rock desertification). However, little attention has been paid to the ecological functions of rock outcrops in karst areas, which tend to be viewed as negative features that add little productivity, but occupy a great deal of space.
Prof. SHEN Youxin and his students of Xishuangbanna Tropical Botanical Garden (XTBG) conducted a study from June 2013 to June 2014 in Shilin County (24°30′-25°03′N, 103°10′-103°40′), Yunnan Province, SW China. They focused on the chemistry of rock surface runoff onto soil patches nearby. They collected and analyzed water received by rock outcrops and the subsequent runoff to soils near rock outcrops to measure the total organic carbon (TOC), total nitrogen (N), total phosphorus (P), and potassium (K) to assess the ecological significance of karst rock outcrops.
The researchers determined TOC, N, P, and K in both the water received by rock outcrops and in water exported to nearby soil patches at all three sampling times in the three ecosystems (rock desertification ecosystem， anthropogenic forest ecosystem，and secondary forest ecosystem). Karst rock outcrops collected organic carbon and nutrients, after which a large proportion of these were exported to nearby soil patches. Both the concentrations and the annual total amounts of organic carbon and N, P, and K in exported water were linked with those of water input to rock outcrops.
When rock outcrops constituted a high percentage (≥ 30%) of the ground surface, the annual export of rock outcrop runoff contributed a large amount of organic carbon and N, P, and K nutrients to soil patches nearby by comparison to the amount soil patches received via atmospheric deposition.
The study revealed that outcrops function as an important medium to receive and store atmospheric organic carbon and nutrients, and redistribute large proportions of them into soil via rock runoff.
The study entitled “Rock Outcrops Redistribute Organic Carbon and Nutrients to Nearby Soil Patches in Three Karst Ecosystems in SW China” has been published in PLoS ONE.
Contact
Prof. SHEN Youxin Ph.D
Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan 666303, China
Tel: 86-871-65160910
E-mail: yxshen@xtbg.ac.cn
