摘要
中国南方岩溶区是土地石漠化广为发生发展的脆弱生态区域。运用面上调查、定位观测和模拟试验相结合的方法,以粤北岩溶山区为例,从地表生态过程的角度对土地石漠化过程进行解析、研究。在轻度石漠化向极重度石漠化发展的过程中,仅2-3 a,植被就从灌草混合群落退化为草本群落,物种减少76%,植被盖度降低87.2%;土壤侵蚀量逐渐加大,土壤物质不断流失和丢失,土层变薄,侵蚀模数呈10多倍、数10倍增加。岩溶坡面特殊的水文过程和水循环模式,使石漠化土地上"四水"转化迅速。随着石漠化程度加重,地表水和壤中水流失量加大,石灰岩脉动式"生长"速度加快,使基岩裸露率由30%—50%增至90%以上,最终导致土壤粗化,养分减少,生物生产量减少89%甚至更多。这表明,土地石漠化过程是由植被退化丧失过程、土壤侵蚀过程、地表水流失过程、碳酸盐岩溶蚀侵蚀过程和土地生物生产力退化过程相互联系、组合而成的土地退化过程,也是岩溶山区土地生态系统演变为石质荒漠系统的地表生态过程。
The karst region of south China is a fragile eco-region where rocky desertification is widespread.Taking karst mountain area of north Guangdong for example,we studied the process of land rocky desertification with the methods of site investigations,station-oriented observations and simulated tests from the perspective of land surface ecological processes.In the process of rocky desertification developing from light to extremely serious,vegetation of that is degenerated from shrubby and herbaceous mixed community to herbaceous community,and species is reduced by 76%,Coverage of vegetation is decreased by 87.2%,soil erosion is aggravated,soil material is losing continuously and soil layer is getting thinner,therefore,modulus of erosion has increased by ten times even dozens of times.Rocky desertification land has special hydrological process and water cycle model.With the aggravation of rocky desertification,more and more surface water and ground water is lost,and the pulsed growth rate of limestone in soil is faster,so that the rate of outcropping bedrock has increased from 30%—50% to more than 90%,eventually leads to soil coarsening,nutrients loss,and 89% or even more reduction of biological production.It shows that land rocky desertification is a process of land degradation,which includes the process of vegetation degradation and loss,soil erosion,surface water loss,carbonate rock corrosion and erosion,and biological productivity of land degradation,meanwhile,it is an evolving process from Karst mountainous area land ecosystems to rocky desert systems.
出处
《生态学报》
CAS
CSCD
北大核心
2010年第3期674-684,共11页
Acta Ecologica Sinica
基金
国家自然科学基金资助项目(30870469
30471421)
关键词
土地石漠化过程
面上调查
观测与模拟试验
地表生态过程
粤北岩溶山区
process of rocky desertification site investigations observations and simulated tests land surface ecological process karst mountain area of North Guangdong
