竹茶混交模式对表层土壤有机碳储量及组分的影响

为探究毛竹林下种植茶树对土壤有机碳储量与碳组分的影响,该研究以毛竹纯林、竹茶混交林和常绿阔叶林为研究对象,采集这3种林分类型的表层(0～10 cm)土壤,测定土壤有机碳(SOC)、碳组分、生物与非生物因素指标。结果表明:(1)竹茶混交林林下植物多样性相较于毛竹纯林显著降低,但其土壤有机碳密度(22.54±2.09)t·hm^-2、碳组分与毛竹纯林无显著差异(P>0.05)。竹茶混交林的矿物结合态有机碳(MOC)为(20.13±1.83)g·kg^-1,占总有机碳的92.66%。常绿阔叶林土壤有机碳密度比竹茶混交林和毛竹纯林高土壤有机碳密度分别高41.15%和41.00%(P<0.05)。(2)3种林分类型土壤微生物量碳(MBC)含量范围为0.58～3.08 g·kg^-1,土壤16S rRNA丰度范围为2.18×10¹⁰ ～5.65×10¹⁰copies·g^-1,固碳基因cbbL丰度范围为0.37×10⁸～ 1.10 ×10⁸ copies·g^-1,土壤微生物碳利用效率范围为0.03～0.28; 3种林分类型之间微生物相关指标不存在显著差异(P>0.05)。(3)3种林分类型SOC与土壤pH、砂粒含量和地上凋落物生物量呈显著负相关,与土壤黏粒含量、粉粒含量、总氮、C:N、总磷和铵态氮含量呈显著正相关(P<0.05)。(4)就不同碳组分而言,颗粒有机碳(POC)和MOC均与土壤pH、砂粒含量和根系生物量呈显著负相关,与土壤含水量、黏粒含量、粉粒含量、总氮、C:N、总磷和铵态氮含量呈显著正相关(P<0.05)。综上表明,竹茶混交改造会造成原生毛竹纯林林下植被多样性下降,但并未造成土壤碳储量下降; 而相较于常绿阔叶林,毛竹经营措施需要改进,以提升其碳汇效益。

Effects of bamboo-tea mixed model on surface soil organic carbon storage and components

In order to explore the effects of planting tea trees under Phyllostachys edulis forest on soil organic carbon storage and carbon components, we took pure bamboo forest, bamboo-tea mixed forest and evergreen broad-leaved forest as the study objects, collected the surface soil(0-10 cm)of these three forest types, and measured soil organic carbon(SOC), carbon components, biotic and abiotic factors. The results were as follows:(1)The diversity of understory plants in bamboo-tea mixed forest was significantly lower than that in pure bamboo forest, but there was no significant differences in soil organic carbon density(22.54 ± 2.09)t·hm^-2 ] and carbon composition between bamboo-tea mixed forest and pure bamboo forest(P>0.05). Mineral-associated organic carbon(MOC)was(20.13 ± 1.83)g · kg^-1, accounting for 92.66% of total organic carbon. The soil organic carbon density of evergreen broad-leaved forest was 41.15% and 41.00% higher than that of bamboo-tea mixed forest and pure bamboo forest(P>0.05).(2)Soil microbial biomass carbon(MBC)content, 16S rRNA gene abundance, cbbL gene abundance and microbial carbon use efficiency of these forest types were(0.58 - 3.08)g·kg^-1,(2.18×10¹⁰ - 5.65×10¹⁰)copies·g^-1,(0.37×10⁸-1.10×10⁸)copies·g^-1, 0.03 - 0.28, respectively. But there were significant differences about these microbial indicators between three forest types(P>0.05).(3)SOC of the three forest types was significantly negatively correlated with soil pH, gravel content and aboveground litter biomass, and significantly positively correlated with soil clay content, silt content, total nitrogen, C:N, total phosphorus and ammonium nitrogen(P<0.05).(4)In terms of different carbon fractions, particulate organic carbon(POC)and MOC were significantly negatively correlated with soil pH, gravel content and root biomass, and significantly positively correlated with soil water content, clay content, silt content, total nitrogen, C:N, total phosphorus and ammonium nitrogen(P<0.05). In conclusion, the mixed transformation of bamboo and tea will cause the decrease of understory vegetation diversity in the original pure bamboo forest, but it will not cause the decrease of soil carbon storage; compared with evergreen broad-leaved forest, it is necessary to improve the management measures of bamboo to improve its carbon sink efficiency.