The Stoichiometric Characteristics and Carbon, Nitrogen Stores of Four Main Coastal Shelterbelt Forests in Pingtan

The vegetation, soil carbon, nitrogen and phosphorus content, stoichiometric characteristics and carbon, nitrogen stores of four main coastal shelterbelt forests were analyzed in Pingtan. Results showed that carbon stores order in these four type of forests are Pinus thunbergii (18920 t/hm2)>Acacia confusa (16202 t/hm2)>Pinus elliottii (14527 t/hm2)>Casuarina equisetifolia (7441 t/hm2); nitrogen stores order are Acacia confusa (1313 t/hm2)>Pinus thunbergii (990 t/hm2)>Casuarina equisetifolia (505 t/hm2)>Pinus elliottii （289 t/hm2). Carbon and nitrogen stores order of different organs of arbor layer plants from high to low are trunk, root, branch and leaf. The trunk containing 3820%-5739% and 2577%-5100% total carbon, nitrogen stores in arbor layer plants, is the main carbon, nitrogen pool. The carbon, nitrogen stores of soil reduces gradually from topsoil to deeper soil profile. There are significantly positive correlation between plant and soil carbon, nitrogen stores (P<001); the carbon, nitrogen stores of soil positively correlated with soil N/P and C/P, and the carbon and nitrogen stores of plant positively correlated with plant C/N, C/P and N/P,C/P (P<001). For this reason, the stoichiometric characteristics have guiding significance to estimate carbon and nitrogen stores. The mean content of soil carbon, nitrogen and phosphorus are 1182 mg/g,098 mg/g and 021 mg/g,respectively,and C/N,N/P and C/P ratio are 1078,421 and 5066,respectively.Nitrogen and phosphorus are the limiting nutrients to coastal shelterbelt forests in Pingtan.