Nutrient Distribution Features Of Subtropical Natural Castanopsis Eyrei Forest

Castanopsis eyrei is one of the main building species of the subtropical evergreen broad-leaf forest.We surveyed the basic situation and biomass of the natural Castanopsis eyrei forest at Lutou Observation Station of Forestry Ecosystem,Hunan,P.R.China.We took samples?vegetation,litter,soil?and analyzed the nutrient contents,accumulation and distribution characteristics of natural Castanopsis eyrei forest.The results are important to reveal and evaluate ecological function and service of natural Castanopsis eyrei forest.Main results below:Nutrient contents of different organs of Castanopsis eyrei are significantly different.The sequence of nutrients in different organs:N,P,K is lesf(13.35,0.60,6.10 g·kg^-1)>branch(7.03,0.38,3.51 g·kg^-1)>bark(6.86,0.24,2.31 g·kg^-1)>root(4.39,0.19,2.54 g·kg^-1)>bole(2.97,0.12,1.48 g·kg^-1);nutrient content changes with diameter is not obvious;the order of the root components:N,P,K,Mg is root?diameter<1 cm?>root?1 cm<d<2 cm?>root?2 cm<d<5 cm?>root?5 cm<d<10 cm?>root?d>10 cm?.There is a significant difference between root?d<1 cm?and root?d>10 cm??P<0.05?.The sequence of macronutrients in shrubs is Ca(7.18 g·kg^-1)>N(6.51g·kg^-1)>K(3.35 g·kg^-1)>Mg(1.14 g·kg^-1)>P0.31 g·kg^-1).The range of micronutrient contents:Cu 3.23?7.52 mg·kg^-1,Fe 213.8?846.59 mg·kg^-1,Zn 17.61?79.51 mg·kg^-1,Mn 88.07?1834.3mg·kg^-1,Cd0.59?6.24mg·kg^-1,Pb 13.43?62.29mg·kg^-1 Ni4.79?9.1 mg·kg^-1,Co 3.84?7.68 mg·kg^-1.Nutrient content is different in different herbs,the order of N,P,K,Ca is Rubus lambertianus(14.88,0.58,7.98,8.57 g·kg^-1)>Dicranopteris dichotoma(10.34,0.56,6.5,2.66 g·kg^-1)>Carex tristachya(9.47,0.42,4.75,1.92 g·kg^-1)>Athyrium nigripes(8.17,0.41,4.31,0.93 g·kg^-1),Mg is Dicranopteris dichotoma(3.15 g·kg^-1)>Rubus lambertianus(2.42 g·kg^-1)>Carex tristachya(2.05 g·kg^-1)>Athyrium nigripes(0.61 g·kg^-1).Soil total N is 1.72?2.53 g·kg^-1,P is 0.29-0.32 g·kg^-1,K is 5.37 to 5.59 g·kg^-1,Ca is 0.35?0.39 g·kg^-1 Mg is 0.73?0.77 g·kg^-1.In addation to Fe,the content of other microelements in soil is significantly lower than macroelements.The content of Fe is significantly greater than other microelements.The content of N,Ca,Mg,Zn,Mn,Cd in the litter is the leaching-release pattern;K,Cu,Fe,Ni,Co is release pattern;P,Pb is the leaching-enrichment-release pattern.The enrichment ability of different layers on the different elements is different.For macronutrient,the sequence is the herb layer>shrub layer>tree layer;for micronutrient,the ability of shrub layer and herb layer si stronger.Total accumulation amount of natural Castanopsis eyrei forest is 5233.19kg·hm^-2,the tree layer?5019.15 kg·hm2,95.91%?>the shrub layer(152.49 kg hm^-2,2.91%)>the herb layer(42.25 kg·hm^-2,0.81%)>the litter layer(19.31 kg·hm^-2,0.37%).