非共生固氮是自然生态系统外源氮输入的重要途径,对生态系统结构、过程和功能均具有重要影响。然而,目前对非共生固氮速率随生态演替变化特征及其主控因素的认识非常欠缺。本研究采用乙炔还原法分别在生长季和非生长季测定了桂西北喀斯...非共生固氮是自然生态系统外源氮输入的重要途径,对生态系统结构、过程和功能均具有重要影响。然而,目前对非共生固氮速率随生态演替变化特征及其主控因素的认识非常欠缺。本研究采用乙炔还原法分别在生长季和非生长季测定了桂西北喀斯特山区不同演替阶段生态系统,即草丛、灌丛和次生林中不同组分(土壤、凋落物和苔藓)的非共生固氮速率。结果表明,不同生态系统组分非共生固氮速率随生态演替变化趋势不一。总体来看,土壤和凋落物的非共生固氮速率表现为随生态演替先降低后升高的趋势,而苔藓的非共生固氮速率在演替早期和中期无显著(p > 0.05)变化,后期显著(p < 0.05)升高。非共生固氮年通量在草丛阶段为(1.21±0.06) kg N/(hm^2·a),显著高于灌丛((0.23±0.03) kg N/(hm^2·a))和次生林((0.65±0.04) kg N/(hm^2·a))。多元线性回归分析结果表明,生态系统各组分含水率、有机碳、全氮和C∶N比的变化是控制非共生固氮速率随生态演替变化的主要因素。研究结果有助于深入认识喀斯特生态系统氮循环特征,并为生态恢复过程中氮累积提供了一种机理解释。展开更多
The role of N2 fixation in structuring plant communities and influencing ecosystem function will be potentially large. In previous study, we investigated nodule biomass and activity, and calculated the amount of N2 fi...The role of N2 fixation in structuring plant communities and influencing ecosystem function will be potentially large. In previous study, we investigated nodule biomass and activity, and calculated the amount of N2 fixation in a naturally established 18-year-old alder (Alnus hirsute (Turcz.) var. sibirica) stand following disturbance by road construction in Takayama, central Japan. In this study, to estimate the facilitation effects by alder on the spatial distribution of the regenerated tree species, we examined the distribution pattern of the regenerated tree species in this naturally established 18-year-old alder stand. The distribution pattern of alder and the regenerated woody species was analyzed in terms of spatial point processes and the regenerated species tended to distribute near the alder site. In particular, bird-dispersed tree species (endozoochory species) with relatively high shade tolerance showed a significant attraction to alder. These results suggest that alder will be used as roost trees and play the role of mother trees for these regenerated species at the degraded site. It was also suggested that the endozoochory species, which occupy 13 of 26 regenerated species in this stand, might regenerate faster than other species at this alder stand.展开更多
文摘非共生固氮是自然生态系统外源氮输入的重要途径,对生态系统结构、过程和功能均具有重要影响。然而,目前对非共生固氮速率随生态演替变化特征及其主控因素的认识非常欠缺。本研究采用乙炔还原法分别在生长季和非生长季测定了桂西北喀斯特山区不同演替阶段生态系统,即草丛、灌丛和次生林中不同组分(土壤、凋落物和苔藓)的非共生固氮速率。结果表明,不同生态系统组分非共生固氮速率随生态演替变化趋势不一。总体来看,土壤和凋落物的非共生固氮速率表现为随生态演替先降低后升高的趋势,而苔藓的非共生固氮速率在演替早期和中期无显著(p > 0.05)变化,后期显著(p < 0.05)升高。非共生固氮年通量在草丛阶段为(1.21±0.06) kg N/(hm^2·a),显著高于灌丛((0.23±0.03) kg N/(hm^2·a))和次生林((0.65±0.04) kg N/(hm^2·a))。多元线性回归分析结果表明,生态系统各组分含水率、有机碳、全氮和C∶N比的变化是控制非共生固氮速率随生态演替变化的主要因素。研究结果有助于深入认识喀斯特生态系统氮循环特征,并为生态恢复过程中氮累积提供了一种机理解释。
文摘The role of N2 fixation in structuring plant communities and influencing ecosystem function will be potentially large. In previous study, we investigated nodule biomass and activity, and calculated the amount of N2 fixation in a naturally established 18-year-old alder (Alnus hirsute (Turcz.) var. sibirica) stand following disturbance by road construction in Takayama, central Japan. In this study, to estimate the facilitation effects by alder on the spatial distribution of the regenerated tree species, we examined the distribution pattern of the regenerated tree species in this naturally established 18-year-old alder stand. The distribution pattern of alder and the regenerated woody species was analyzed in terms of spatial point processes and the regenerated species tended to distribute near the alder site. In particular, bird-dispersed tree species (endozoochory species) with relatively high shade tolerance showed a significant attraction to alder. These results suggest that alder will be used as roost trees and play the role of mother trees for these regenerated species at the degraded site. It was also suggested that the endozoochory species, which occupy 13 of 26 regenerated species in this stand, might regenerate faster than other species at this alder stand.
