摘要
中国东部在全新世气候时为草原或森林草原环境，并广泛发育了富含有机质和养分的黑土层，但这层黑土层之下，即为厚层的沙层，从而构成了上述地区潜在荒漠化的沙源。上述地质特点注定了东部的黑土地地区，并非宜农区，而应当为载畜量有限的牧业区。但是，历史时期，特别是清朝光绪年间以后及民国时期，东部的黑土地被大量放垦，草场退化和土地沙化加剧。建国后的“大跃进”及“文化大革命”时期，在错误理论指导下，东部的草原地区再次掀起了史无前例的垦荒种地，及至现在，很多地区仍在进行大面积的垦荒。长期的垦荒，已经使东北的黑土地在风力的吹扬下，被剥蚀殆尽，其下的厚层第四纪沙源活化，从而使东北黑土地地区成为中国目前荒漠化危害最为严重的地区。事实上，东北草原地区的自然条件良好，水分充沛，只要政府采取措施，当地的植被是比较容易恢复的，也是治理荒漠化最为经济和现实的地区，这是干旱的西北地区所不能比拟的。但是，倘若不及时采取措施的话，中国东北的黑土地地区将沦为第２个西北。
The northeastern region of China lies in the semi-arid to sub-humid climate zone, with averaged annual precipitation of>400 mm. During Holocene, the northeastern China is steppe environment and a sandy loam soil is developed in this region. However,under the surface loam soil is the thick Quaternary sand bed, which forms the potential sources for the desertification. The existence of the low-buried sand sources make the northeastern China being a most potential desertification region of China, and thus it is not suitable for cultivation. According to historical accounts,the earliest inhabitants of the semi-arid grasslands of northeastern China were nomadic tribes who herded sheep and cattle and usually moved in search of water and grass. But,in central and southern China, a large population of Hans (today, the Hans make up 92% of the population in China) settled extensive parts of the country and mainly lived on a farming-based economy. There were numerous national conflicts between the Hans and nomads, leading to the migration of the pastoral-farming boundary. The impacts of nomadic economy on the landscape were spread evenly and possibly at low levels; therefore, this pastoral existence did not cause severe environmental deterioration. However, when large populations of Hans settled in the same regions, extensive areas of grassland were cultivated. The high impact of the agricultural economy removed the vegetation cover and caused the deflation of the surface loam soil, resulting in eolian sand reactivation. Historical accounts indicate that the earnest cultivation and land reclamation in the northeastern China can be dated back to about 7 200aB.P. But, probably due to the low-efficiency and only the sparse cultivation activities in the early time, the earliest recorded desertification occurred in the late Liao Dynasty of about 1 100years ago, after the first episode of human migration and cultivation in this region. Although the earliest sand reactivation occurred in the late Liao Dynasty, during the subsequen
出处
《第四纪研究》
CAS
CSCD
北大核心
2001年第1期72-78,共7页
Quaternary Sciences
基金
国家自然科学基金!(批准号:49972059)资助项目
国家重点基础研究发展规划项目!(批准号:G1999043402)
