The Evaluation On Ecological Benefits Of Caribbean Pine (Pinus Caribaea) Transformation Forests

Abstract:There are a large number of low efficiency pure forests in Guangdong Province,which become a major problem needed to be solved for forest transformation.In Caribbean pine?Pinus caribaea?transformation forests of Foshan City.Three plots consisted primarily of Castanopsis fissa,Schima superba and without transformation trees?CK?were selected,respectively.We investigated tree growth?diameter,tree height and crown width?,photosynthesis,chlorophyll fluorescence characteristics,diversity of understory vegetation,litter accumulation,soil physical and chemical properties?pH,organic matter,total nitrogen N,total phosphorus P,total potassium K,available nitrogen,available phosphorus,available potassium?,soil microbial number and enzyme activity.The results are as follows:1.C.fissa grew best with maximum diameter at breast height?DBH?and crown width among all transformation tree species in the C.fissa plot.The tree height growth of S.superba was the fastest,whereas DBH and crown growth of Camellia oleiferain was the fastest in the S.superba plot.2.Net photosynthetic rate?P_n?,stomatal conductance?G_s?,intercellular CO₂concentration?C_i?and transpiration rate?Tr?decreased in the order of Acacia auriculaeformis>Artocarpus nitidus ssp.Lingnanensis>C.fissa>C.Oleifera in the C.Fissa plot,and in the order of S.superba>C.Oleifera>Carallia brachiata>Symplocos lancifolia in the S.superba plot.3.In the C.fissa and S.superba plots,except for the PSII,energy dissipation of Y?NO?,maximal fluorescence value?F_m?,PSII actual quantum efficiency Y?II?,the apparent electron transfer rate?ETR?and non photochemical quenching coefficient?NPQ?decreased in the order of C.Oleifera>C.fissa>A.lingnanensis>C.fissa>A.auriculaeformis in the C.fissa plot,and in the order of C.Oleifera>S.lancifolia>S.superba>C.Brachiata in the S.superba plot.4.SPAD decreased in the order of A.lingnanensis>C.Oleifera>A.auriculaeformis>C.Fissa in the C.Fissa plot,and in the order of C.brachiata>C.Oleifera>S.lancifolia>S.Superba in the S.superba plot.Specific leaf weight decreased in the order of A.auriculaeformis>A.lingnanensis>C.fissa>C.Oleifera,and in the order of S.superba>C.brachiata>S.lancifolia>C.Oleifera in the S.superba plot.5.^In the S.superba plot,the content of nitrogen in leaf decreased in the order of Acacia auriculaeformis>Artocarpus nitidus ssp.Lingnanensis>C.fissa>C.Oleifera and in the order of C.brachiata>S.lancifolia>S.superba>C.Oleifera in the S.superba plot.;The content of phosphorus in leaves decreased in the order of Acacia auriculaeformis>Artocarpus nitidus ssp.Lingnanensis>C.fissa>C.Oleifera in the C.Fissa plot,and in the order of C.Oleifera>S.lancifolia>S.Superba>C.brachiata in the S.superba plot.The content of potassium in leaves decreased in the order of Artocarpus nitidus ssp.lingnanensis>A.auriculaeformis>C.Fissa>C.Oleifera in the C.Fissa plot,and in the order of S.superba>C.Oleifera>S.lancifolia>C.brachiata in the S.superba plot.6.Principal component analysis was used for the indexes of photosynthetic fluorescence and leaf nutrients of trees in the two plots,indicating the score of principal component analysis decreased in the order of C.Oleifera>A.lingnanensis>A.auriculaeformis>C.Fissa in the C.fissa plot,and in the order of C.brachiata>S.lancifolia>C.Oleifera>S.Superba was in the S.superba plot.7.Principal component analysis was used for the indexes of soil nutrient,soil microorganism,enzyme of the three plots indicated that the score of principal component analysis decreased in the order of the S.superba plot>the C.Fissa plots>CK.8.The importance value of Melastoma candidum was the greatest among shrub species in the C.Fissa and S.superba plots,and that of Machilus chrysotricha and Trema cannabina was the greatest among shrub species in CK plot.The importance value of Oplismenus undulatifolius was the greatest among herb species in the three plots.9.The Simpson diversity index and Shannon-Wiener diversity index of the shrub species decreased in the order of the S.superba plot>the C.Fissa plot>CK plot,whereas evenness index J_sw and Jsi of the shrub species among the three plots were the highest in CK plot;The Simpson diversity index of the herb species in the C.Fissa plot was greater than that of the S.superba plot and CK.Shannon-Wiener diversity index decreased in the order of the C.Fissa plot>the S.superba plot>CK,whereas evenness index J_sw decreased in the order of C.Fissa plot>CK>S.superba plot,and evenness index Jsi decreased in the order of CK>S.superba plot>C.Fissa plot.10.The litter accumulation of the three plots the C.Fissa plot>the S.superba plot>CK.The N and P contents of litter N content decreased in the order of CK>the S.superba plot>the C.Fissa plot,the K content of litter decreased in the order of the S.superba plot>the C.Fissa plot>CK.The nutrient content of litter layer decreased in the order of N>K>P.11.The soil bulk density of 0-20 and 20-40 cm soil layers was was 1.50 and 1.66g·cm^-3,respectively.There was not difference in soil capillary porosity among the three plots.The capillary water holding capacity,soil porosity,soil non-capillary porosity and soil aeration porosity of the upper soil layer were greater than the lower soil layer in the C.Fissa plot and the S.superba plot,whereas CK was on the contrary.12.The soil pH values of the two soil layers ranged from 4.0 to 4.5 in the three plots,which was strongly acidic soil.Soil organic matter in CK plots was significantly lower than the other plots,soil organic matter content in the lower soil layer of three plots was significantly greater than the corresponding the upper layer;the total N content of the upper and lower soil layers decreased in the order of the S.superba plot>the C.Fissa plot>CK,contents of total N and total P in upper soil layer were significantly greater than the corresponding the lower soil lower in the three plots;the total potassium content in upper soil layer decreased in the order of CK>the S.superba plot>the C.fissa plot,whereas the lower soil layer was on the contrary;available N and P contents in the two soil layers decreased in the order of the S.superba plot>the C.Fissa plot>CK;contents of available N,P and K in the upper soil layer were higher than the lower soil layer in three plots.13.There were significant correlations between N content and P content,between N content and K content as well as between P content and K content per unit leaf area;Strong positive correlations were also present between the net photosynthetic rate and the contents of N,P and K in leaves of different tree species;the catalase activity of soil significantly increased with increasing total N content,available N and organic matter;the phosphatase activity was significantly related to organic matter,total N,available N and available P contents;the urease activity showed correlation with the pH value;Significant correlations also existed between PH value and soil organic matter,total N and available N contents.