• ISSN 1008-505X
  • CN 11-3996/S

生物质炭介导微生物对马尾松和杉木根系氮磷利用效率的影响

Effects of biochar via microbial communities on nitrogen and phosphorus use efficiency in Pinus massoniana and Cunninghamia lanceolata

  • 摘要:
    目的 研究生物质炭添加对林木生长和根系养分利用效率的影响,为人工林可持续经营和森林土壤功能提升提供理论依据和技术参考。
    方法 以1年生马尾松和杉木幼苗为试验对象。设置4个生物质炭添加量处理,即0 t/hm2(对照 CK)、5 t/hm2(低量,LB)、10 t/hm2 (中量,MB)、20 t/hm2(高量,HB)。测定马尾松和杉木幼苗的根系构型、土壤微生物群落结构,并计算根系养分利用效率。
    结果 与对照相比,3个生物质炭添加处理显著增加马尾松根系生物量19.9%~30.7%。与CK相比,HB处理的马尾松和杉木细根总长度分别增加了24.3%和12.7%;MB和HB处理的马尾松细根表面积分别增加了20.7%、41.2%,体积分别提高了24.9%、51.5%;MB处理降低杉木细根表面积13.5%和细根体积16.7%;LB处理马尾松和杉木细根氮含量分别降低了16.1%、12.2%;LB和MB处理马尾松细根磷含量分别降低了18.6%、22.0%。LB和MB处理分别显著增加马尾松土壤微生物总生物量28.9%和25.5%,LB处理增加杉木土壤微生物总生物量51.8%。LB处理下,真菌丰度与根长、根系表面积、根系体积、根系氮吸收量均呈显著负相关;MB处理下,菌根真菌丰度与根长、根系表面积、根系体积、根系氮磷吸收利用率均呈极显著正相关,但与微生物群落主要类群呈显著或极显著负相关;HB处理下,仅真菌丰度与根系生物量呈显著负相关。对照处理下,氮吸收效率受真菌和放线菌的影响较大,磷吸收效率受真菌的影响较大。LB处理下,氮吸收效率受根系生物量、革兰氏阴性菌、放线菌的影响较大;MB处理下,氮吸收效率受根长、根系表面积、根系体积影响显著,磷吸收效率受根系表面积、根系体积、根系氮含量、细菌和放线菌的影响较大;HB处理下,氮吸收效率受根系生物量、根系体积、菌根真菌的影响较大,磷吸收效率受根系生物量、根长、根系表面积的影响较大。
    结论 生物质炭添加对亚热带人工林生长和养分吸收有正向促进作用。生物质炭施用量显著影响微生物总量和群落结构,进而调控根系氮磷养分的吸收利用。低生物质炭用量下,细菌和放线菌对根系氮磷吸收利用率的影响较大,而中、高生物质炭施用量降低了微生物生物量,提高了真菌占比,氮磷的吸收和利用主要受菌根真菌的影响。高量生物质炭适宜于马尾松,而杉木适宜施用低量生物质炭。

     

    Abstract:
    Objectives This study investigated the effects of biochar application on tree growth and root nutrient use efficiency, aiming to provide theoretical foundations and technical references for the sustainable management of plantation forests and the enhancement of forest soil functions.
    Methods An experiment was conducted using one-year-old seedlings of Masson pine (Pinus massoniana) and Chinese fir (Cunninghamia lanceolata) as the research materials. Four biochar application rate were established: 0, 5, 10, and 20 t/hm2, corresponding to control (CK), low (LB), medium (MB), and high (HB) application levels, respectively. Root architecture and soil microbial community structure were examined, and root nutrient use efficiency of the seedlings were calculated for Masson pine and Chinese fir.
    Results All three biochar application treatments significantly increased the root biomass of Masson pine by 19.9%−30.7%. Compared with CK, the total fine root length of Masson pine and Chinese fir increased by 24.3% and 12.7%, respectively, under the HB treatment. The fine root surface area of Masson pine increased by 20.7% and 41.2%, and the volume increased by 24.9% and 51.5% under the MB and HB treatments, respectively. The MB treatment reduced the fine root surface area and volume of Chinese fir by 13.5% and 16.7%, respectively. The LB treatment decreased the nitrogen content in the fine roots of Masson pine and Chinese fir by 16.1% and 12.2%, respectively. The LB and MB treatments reduced the phosphorus content in the fine roots of Masson pine by 18.6% and 22.0%, respectively. The LB and MB treatments significantly increased the total soil microbial biomass of Masson pine by 28.9% and 25.5%, respectively, while the LB treatment increased the total soil microbial biomass of Chinese fir by 51.8%. Compared with CK, under the LB treatment, fungi showed a significant negative correlation with root length, root surface area, root volume, and root nitrogen uptake. Under the MB treatment, mycorrhizal fungi exhibited a highly significant positive correlation with root length, root surface area, root volume, and the uptake and utilization efficiency of root nitrogen and phosphorus, while other components of the microbial community structure showed significant or highly significant negative correlations. Under the HB treatment, only fungi showed a significant negative correlation with root biomass. In the CK treatment, nitrogen uptake and utilization efficiency were significantly influenced by fungi and actinomycetes, while phosphorus uptake efficiency was significantly influenced by fungi. Under the LB treatment, nitrogen uptake efficiency was significantly influenced by root biomass, gram negative bacteria, and actinomycetes. Under the MB treatment, nitrogen uptake was significantly affected by root length, root surface area, and root volume, while phosphorus uptake was significantly influenced by root surface area, root volume, root nitrogen content, bacteria, and actinomycetes. Under the HB treatment, nitrogen uptake efficiency was influenced by root biomass, root volume, and mycorrhizal fungi, while phosphorus uptake efficiency was significantly influenced by root biomass, root length, and root surface area.
    Conclusions Biochar application has a positive promoting effect on the growth and nutrient uptake of subtropical plantation forests. Biochar application rates affect the total quantity and structure of soil microorganisms, which in turn influences the uptake and utilization of nitrogen and phosphorus by roots. At low biochar application rates, bacteria and actinomycetes have a greater impact on the uptake and utilization efficiency of root nitrogen and phosphorus. In contrast, medium and high application rates reduce microbial biomass, increase the proportion of fungi, and make nitrogen and phosphorus uptake and utilization primarily dependent on mycorrhizal fungi. High biochar application rates are suitable for Masson pine, while Chinese fir benefits more from low biochar application rates.

     

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