Biomass And Nutrient Of Fine Root In Masson Pine Mixed Woods In Zongyang Area

To understand the effect of tree species composition on fine root biomass and related nutrients, 5 kinds of 20-years-old masson pine and broad-leaved mixedwoods were analyzed in Dashan area of Southern Anhui with variable being the proportion of masson pine. Several tools such as combining complementary methods, soil drilling method and inner growth method were used to study fine root biomass distribution and fine root biomass growth in masson pine and broad-leaved mixedwoods. The major research contents included the seasonal dynamics of fine root biomass and nutrient contents, fine root biomass growth, and soil nutrient contents. The relationship between fine root and soil physicochemical property was also studied. The results are as following:(1) Differences in species composition had a great effect on fine root biomass. Differences fine root biomass in 5 kinds of stands were as following: 41-60%﹥0-20%﹥21-40%﹥81-100%﹥61-80%. The average value of fine root biomass was 1.693t·hm^-2 in masson pine and broad-leaved mixedwoods.(2) Fine root biomass appeared more in the surface soil layer than in the lower layer for all sampling stands in masson pine and broad-leaved mixedwoods. The vertical distribution might be closely related to soil depth and root characteristics in Dashan area.(3) Fine root biomass seasonal dynamics of five kinds of masson pine and broad-leaved mixedwoods presented a unimodel curve.The maximum occurred in June and July, and the minimum in January. As to net value of biomass, the highest was in 41-60% masson pine mixedwoods.(4) The annual growth of fine root in 0-30cm soil layer of all sampling stands was in the range of 0.614⁰.988 t·hm^–2·a^–1. The largest growth occured form June to August, and the smallest form December to next March. The annual production of fine root in all stands were ranked by 41-60%(0.988t·hm^–2·a^–1)﹥61-80%(0.899 t·hm^–2·a^–1)﹥21-40%(0.775 t·hm^–2·a^–1)﹥81-100%(0.745 t·hm^–2·a^–1)﹥0-20%(0.614 t·hm^–2·a^–1).(5) Both SRL (Specific root length) and (Root length density) in 0-30cm soil layer in 41-60% stand were higher than other four kinds of stands, and the vertical changes of RLD in 41-60% stand was lower compared to the others.(6) The nutrient storages of N, P, K, Ca, Mg of fine-root gradually decreased from surface to low soil layer, and the nutrient storages in 0-10cm soil layer were obviously higher than 10-20cm and 20-30cm soil layer. The N storages of fine root were ranked by 41-60%﹥61-80%﹥80-100%﹥21-40%﹥0-21%, while 80-100%﹥41-60%﹥61-80%﹥0-21%﹥21-40% were for the K storages of fine root. The P storages of fine root were ranked by 41-60%﹥80-100%﹥61-80%﹥0-21%﹥21-40%. The Ca storages of fine rootwere ranked by 41-60%﹥0-21%﹥80-100%﹥61-80%﹥21-40% and the Mg storages offine root were ranked by 41-60%﹥61-80%﹥80-100%﹥21-40%﹥0-21%.(7) In 0-10cm soil layer, fine root biomass had a significantly positive relation withtotal P, available P, organic matter, soil porosity and water content. In 10-20cm soil layer,fine root biomass had a significantly positive relation with total P, organic matter, soilporosity, water content and available K. In 20-30cm soil layer, fine root biomass had asignificantly positive relation with available K, organic matter, soil porosity, water contentand total K.