Development Of Oasis Agriculture And Ecology Environmental Changes Of River Talimu Valley

environment in River Talimu valley in the historical time, the development of oasis agricultural there is the dominant and crucial factor. Following the agricultural development history in Loulan kingdom lying to the northwest part of Luobupo and the center of collecting waters of River Talimu from Han to Tang dynasties as the main line, using the information of geographical environment, stratum sediments, dry climate and atmospheric circulation(basic ecological factors) inherited from Tertiary and Quaternary, we studied the effects of oasis agricultural cxploration under the conditions of war stress and 憈he silk road?trade (ecological disturbing factors) on ecological environment, and put forward a hypothesis called 慳bandoning cycle of oases?to the arid area of River Talimu valley: abandoning cycle of oases is positively correlated to both agricultural development density and the speed of wind-corroding(or the speed of wind-sand) with the theoretical model as: a~s/pv a= abandoning cycle of oases (unit: year) p= agricultural development intensity (expressed by exponent. It would be 慖?if all the vegetation had been destroied) s~oasis area (unit: square kilometers) vthe speed of wind-corroding (unit: Square kilometers/year). To test and verify the above theoretical model, we selected the relics of Hetian area lying in the branches valley of River Talimu including River Pishan, River Sangzhu, River Hetian, River Keliya and River Niya etc to study in this article. Hetian lies in the south of Takelamagan where most relics in the history are distributed, and the oases there is surrounded by desert. There are more than fifty relics in l-letian area and 21 of them have well recorded. The relationship of the abandoning of these oases with the degree of agricultural development was analyzed and the result is consistent with the above hypothesis, e.g., the frequency of oasis抯 abandoning is positively correlated with the degree of agricultural development; the peak value of oasis抯 abandoning is synchronous or lag with the period of agricultural development, and the lagging time usually 300 to 400 years; abandoning cycle of oases is 500 to 600 years; oasis抯 stability is negatively correlated with the degree of agricultural development. Hereinto, the degree of agricultural development is positively correlated with farmer 3 Abstract population, farming time, advancement of farming tools, efficiency of farming management, production ability of farmers, pressure of farmers?extortion to the land arid so on. The theoretical model for this is as follows: P=F(X1 ?X2?X3 X4 X3?X6) Where P is the degree of agricultural development of oases, F is a function and X~, X2, X3, X4, X5, X6 are farmer population, farming time, advancement of farming tools, efficiency of farming management, production ability of farmers, pressure of farmers?extortion to the land respectively. This article also analyzed the scope and degree of civilian抯 vegetation-consumption of Loulan kingdom, and proved that exorbitant vegetation-consumption is one of the most important reasons leading to the destruction of Loulan抯 vegetation. Furthermore, it is also found that environmental change were influenced indirectly by the change of production model and institution with the...