贡嘎山天然林营养元素生物循环特征

对贡嘎山东坡常绿与落叶阔叶混交林和冷杉林营养元素分布和生物循环进行研究.结果表明:常绿与落叶阔叶混交林、冷杉成熟林和中龄林N、P、K总积累量依次为1 720.076、2 103.290、1 748.229 kg/hm2；N、P、K的归还量依次为66.577、34.850、33.917 kg/(hm2a)； 存留量依次为73.759、95.387、81.603 kg/(hm2a).冷杉林保持N、P、K能力强，N、P、K循环速率比常绿与落叶阔叶混交林低. 

Characteristics of nutrient biocycling of natural forests on the Gongga Mountain

Hengduan Mountains form the southeastern margin of the Qinghai-Tibetan Plateau. The main culmination is the Gongga Mountain, reaching 7 556 m in western Sichuan Province. The vertical vegetation belts on the east slope of the Gongga Mountain are complete. Natural forests are distributed in altitude from 1 800 m to 3 600 m. Abies fabri forest is the main vegetation type.Nutrient distribution and biocycling of natural forests on the Gongga Mountain were studied. The results showed that N,P and K storage in evergreen and deciduous broad-leaved mixed forest, Abies fabri mature and middle aged forests averaged 1 720.076, 2 103.290 and 1 748.229 kg/hm 2, respectively; average return by littefall was 66.577, 34.850 and 33.917 kg/(hm 25a), respectively; retention averaged 73.759, 95.387 and 81.603 kg/(hm 25a). Abies fabri forests have a stronger N, P and K retaining ability, and a lower cycling rate of N,P and K than that of evergreen and deciduous broad-leaved forests.