Dynamic Variations of Landscape Pattern and the Landscape Ecological Functions in the Source Area of the Yellow River

The study of landscape heterogeneity is an important means to researching regional ecological processes. According to remote sensing data of 1970s, 1980s and 1990s, some representative quantitative indices of the landscape spatial structure and landscape heterogeneity were selected to study the changes in landscape ecological structure and landscape pattern in the source area of the Yellow River using FRAGSTATS calculation method. In recent 30 years the landscape spatial pattern in the area tended to become fragmentized and diversified, main internal cause for this lies in the rapid development of such landscape types as the alpine cold sparse grassland, black soil-weed grassland and desertified grassland, their areas increased by 384.16% 66.63% and 421.09% respectively. Both the landscape diversity and spatial heterogeneity in the area increased and the change in the landscape pattern was most intense in the 10 years from 1980~1990, such a change reflects the continuous deterioration of eco-environment in the area.; The relationship and feedback between landscape pattern, function and process serve to describe the behavior of a regional landscape. Based on landscape function characteristics such as biological productivity, soil nutrient content, vegetative cover, etc. a quantitative method and digital model for analyzing evolving landscape functionality in the headwaters area of the Yellow River in the People's Republic of China were devised. Through the analysis of three-phase remote sensing data from 1975, 1985 and 1995 and based upon the well-defined characteristics of this region's evolving landscape over the past 30 years, the attendant ecology of the different functional landscape ecotypes was investigated. Between 1975 and 1995 the area of ACS meadow (alpine cold meadow and steppified meadow) in the source area of the Yellow River has decreased by 27.25%, ACSW meadow (alpine cold swamp meadow) has decreased by 27.04%, ALP steppe (alpine steppe) by 38.18% and lakes by 9.78%. The grass biomass production decreased by 752.37 Gg, of which ACS meadows accounted for 83.8% of these losses. The overall stock capacity of the headwaters area of the Yellow River decreased by 518.36 thousand sheep units. Soil nutrients showed a similar pattern, soil nutrient loss was greater from 1985～1995 than from 1975～1985. Changes in the overall ecological functionality of the area were not simply a result of a summation of the changes associated with individual evolving landscapes, but rather an integration of positive and negative influences. Landscape evolution occurs in two main directions: degradation and strengthening. An understanding of the direction, force and integration of parameters influencing landscape evolution as it impacts the attending ecosystems can allow one to foresee how the landscape of the Yellow River source area will evolve in the coming years.