一、土壤有机质消长与生态环境的关系陇东系指陇山之东,东有子午岭,西有六盘山(陇山),西、北与宁夏接壤,东、南与陕西相邻的地区。泾河水系从西北流贯东南,水绕山环,沃野千里,三千多年前,曾是西周文化发祥地。当时森林面积广阔,东西两面山地为原始森林,整个覆被率达53％,其余是一片肥美草原,因此泾水清沏,水土流失十分轻微。此后人口剧增,砍伐森林,垦殖草原,水土流失渐趋严重。公元25—618年即东汉至隋代六百年间以牧为主,控制了水土流失,土壤 First, the relationship between the growth and decline of soil organic matter and the ecological environment Longdong refers to the east of Longshan, east Ziwuling, west of Liupanshan (Longshan), west, north and Ningxia border, east, south and adjacent areas of Shaanxi. Jing River flows through the southeast from northwest, water around the mountain ring, fertile ground, thousands of years ago, was the birthplace of Western Zhou culture. At that time, the forest area was vast. Both the east and west mountains were primeval forests. The entire coverage rate was 53% and the rest was a fertile grassland. As a result, Jing water was drained and water and soil loss was very slight. Since then, population growth, deforestation, grassland cultivation, soil erosion is getting worse. The year 25- 618 was mainly dominated by grazing during the Eastern Han Dynasty and the Sui Dynasty in the six hundred years, controlling soil and water loss, soil