Biomass Productivity of Taiwania flousiana Plantation and Successive Rotation Plantation of Cunninghamia lanceolata in Cutover Forest Land of C.Lanceolata

[Objectives] The aim was to reveal the accumulation characteristics and differences of biomass productivity of Taiwania flousiana plantation and successive rotation plantation of Cunninghamia lanceolata .[Methods] The biomass and productivity of the 23-year-old T. flousiana plantation and successive rotation plantation of C. lanceolata were studied at Nandan Shankou Forestry Farm of Guangxi., China.[Results] There were differences in the biomass distribution of different organs of T. flousiana plantation and successive rotation plantation of C.lanceolata. The biomass for the T. flousiana plantation was distributed in the order of stem 〉 branch 〉 leaves 〉 bark, and the successive rotation plantations of C. lanceolata was stem〉 root 〉 branch 〉 bark 〉 leaves. The biomass of tree layer of 23-years-old T. flousiana plantation and successive rotation plantations were 195.21 and 136.82 t/hm^2, respectively, including 113.32 and 87.91 t/hm^2 of economic biomass （stem）. The annual net productivity of tree layer of the 2 plantations were 8.49 and 5.95 t/（hm^2·a）, respectively, including 5.14 and 3.82 t/（hm^2·a） of stem. Therefore, T. flousiana plantation has higher biomass accumulation ability than that of successive rotation plantations of C.lanceolata, and can be used as an excellent substitute tree species for the regeneration of C.lanceolata cutover plantation.[Conclusions]

Carbon Accumulation and Distribution in Ecosystems of Taiwania flousiana Plantation and Successive Rotation Plantation of Cunninghamia lanceolata

The 23-year-old T. flousiana plantation and successive rotation plantation of C. lanceolata at Shankou Forest Farm of Nandan County, Guangxi were tested by the method of plot investigation combining with biomass measurement. Carbon storage and spatial distribution of different components in the two forests were analyzed. The results indicated that carbon content in different organs of T. flousiana ranged from 426.0 to 503.9 g/kg, and the order was bark 〉stem 〉 root 〉 branch 〉 leaf. The carbon contents in shrub, herb and litter layers were452.9 , 408.0 and 428.9 g/kg, respectively. Carbon content in the soil （0 -80 cm）was 16.59 g/kg. The carbon content in different organs of C. lanceolata ranged from 464.5 to 508.9 g/kg, and the order was bark 〉 stem 〉 branch 〉 root 〉 leaf. The carbon contents in shrub, herb and litter layers were 456.2, 416.3 and 468.1 g/kg, respectively. Carbon content in the soil （0 -80 cm）was 15.77 g/kg. Total carbon storage amounts of T. flousiana plantation and successive rotation plantation of C. lanceolata were 245.83 and 213.52 t/hm^2, respectively. The carbon storage order of different structure layers from T. flousiana plantation and successive rotation plantation of C. lanceolata was soil layer （0 -8 0 cm） 〉 vegetation layer 〉 litter layer. Annual net productivity in the arbor layers of T. flousiana plantation and successive rotation plantation of C. lanceolata plantations was 10.75 and 17.13 t/（hm^2 · a） ; annual net carbon fixation amounts were estimated as 5.05 and 3.47 t /（hm^2 · a） ; annual net absorption C02 amounts were 18.53 and 12.73 t/（hm^2 · a） respectively.

A recommended rate for application of Chaetomium globosum ND35 fungus fertilizer on poplar plantations in China

Previous studies showed that Chaetomium globosum ND35 fungus fertilizer can improve the microbial community structure and enzyme activities of replanted soil. However, it remains unclear whether can improve the physiological and ecological characteristics of plants under successive rotation. In this study, we investigated the photosynthetic, physiological, and biochemical indexes including photosynthetic parameters, chlorophyll fluorescence, and chlorophyll content of 1-yeax-old poplar seedlings under seven different doses （range from 0 to 1.67 g kg-1） of C. globosum ND35 fungus fertilizer to study the effects of fungus fertilizer on photosynthesis of Poplar. Our results showed that： （1） With increasing application of fungus fertilizer in replanted soil, chlorophyll content of poplar leaves （Chl） increased, while physiological indexes such as electron transport rate （ETR）, net photosynthetic rate （Pn）, quantum efficiency （φ）, nitrate reductase （NR） activity and root vigor initially increased and then declined. Meanwhile, heat dissipation that depended on the xanthophyll cycle declined and nonphotochemical quenching （NPQ） initially increased and then decreased. When the dose of C. globosum ND35 fungus fertilizer was 0.67 g kg-1 （T3） and 1.00 g kg-1 （T4）, excess light energy of photosynthetic apparatus was reduced, and photosynthetic apparatus distributed more light energy to the direction of photochemical reactions, which improved the efficiency of energy use. Plant height and biomass of leaves, stems, and roots were maximum at T3. We conclude that applying appropriate amounts of C. globosum ND35 fungus fertilizer can improve root physiological activity and capacity for use of light by poplar leaves. This can improve the operating states of the photosynthetic apparatus and lead to increased photosynthetic efficiency of poplar leaves and accumulation of dry matter.This suggests a strategy to alleviate the successive rotation obstacle of soil nutrient depletion.

Soil microbial community structure and function responses to successive planting of Eucalyptus

Many studies have shown soil degradation after the conversion of native forests to exotic Eucalyptus plantations. However, few studies have investigated the long-term impacts of short-rotation forestry practices on soil microorganisms. The impacts of Eucalyptus successive rotations on soil microbial communities were evaluated by comparing phospholipid fatty acid （PLFA） abundances, compositions, and enzyme activities of native Pinus massoniana plantations and adjacent 1st, 2nd, 3rd, 4th generation Eucalyptus plantations. The conversion from P. massoniana to Eucalyptus plantations significantly decreased soil microbial community size and enzyme activities, and increased microbial physiological stress. However, the PLFA abundances formed ＂U＂ shaped quadratic functions with Eucalyptus plantation age. Alternatively, physiological stress biomarkers, the ratios of monounsaturated to saturated fatty acid and Gram＋ to Gram- bacteria, formed ＂∩＂ shaped quadratic functions, and the ratio of cy17：0 to 16： 1ω7c decreased with plantation age. The activities of phenol oxidase, peroxidase, and acid phosphatase increased with Eucalyptus plantation age, while the cellobiobydrolase activity formed ＂U＂ shaped quadratic functions. Soil N：P, alkaline hydrolytic nitrogen, soil organic carbon, and understory cover largely explained the variation in PLFA profiles while soil N：P, alkaline hydrolytic nitrogen, and understory cover explained most of the variability in enzyme activity. In conclusion, soil microbial structure and function under Eucalyptus plantations were strongly impacted by plantation age. Most of the changes could be explained by altered soil resource availability and understory cover associated with successive planting of Eucalyptus. Our results highlight the importance of plantation age for assessing the impacts of plantation conversion as well as the importance of reducing disturbance for plantation management.