喀斯特生态恢复过程中土壤原生动物的指示作用研究

摘要

This study aimed to examine the bioindication of soil protozoa to Karst ecological restoration, and in turn to better understand the Karst ecological restoration processes and mechanisms and to provide scientific basis for the Karst ecological mangement. The investigation was carried out at Guzhou village of Guangxi Province, the artificial forest plots with a standing age gradients (2, 4, 8, 12 years) and the adjacent degraded plot as the control were selected to investigate responses of topsoil protozoa community to the Karst reforestation. In our study, the collected protozoa were identified as 22 groups, including 8 groupsof Mastigophora dominated by Kinetoplastida, ChrysomonadidaandEuglenida, 4 groupsof Sarcodina dominated byAmoebida and Arcellinida,10 groupsof Ciliophoradominated byHypotrichida, Prostomatida, Colpodidaand Pleurostomatida. The total number of soil protozoa increased from 425×103 in per gram dry soil in the control plots to 633×103 in the 12-yr forested plots with a mean annual rate of 17.7×103·in per gram dry soil. Soil protozoa species number (SN) increased from17 in the control plots to 22 in the 12-yr forested plots with a mean annual rate of 17.7×103·in per gram dry soil. The protozoa richness index (SR, 3.10~3.30) in the forested plots was significantly higher by 19%~27% than that (2.64) in the control plot. The Shannon-Wiener index (H′, 2.59~2.77) and the evenness index (J′, 0.86~0.91) showed no significant changes following the reforestation. As soil basic fertility indicators, porosity, moisture, total organic carbon (TOC) and dissolved carbon (DOC), total nitrogen (TN), available nitrogen (AN) and microbial biomass carbon (MBC) contents generally increased with increasing forestation ages, with mean annual rates of 3.84%, 6.85%, 3.89%, 11.5%, 4.20%, 7.13% and 24.8%, respectively, and all were significantly positively correlated with protozoa total number, SN andH′ (except for TOC with SN and AN withH′;P < 0.01) under the reforestation. Our results indicated that soil protozoa community size and diversity sensitively respond to the Karst eco-restoration and show co-succession together with soil basic fertilities, and can thus be bio-indicator for Karst eco-restoration.%为了揭示土壤原生动物对喀斯特生态恢复的指示作用，进而为深入了解喀斯特生态恢复的过程机制和构建恢复技术体系提供科学依据，本研究以广西古周村典型喀斯特景观为代表，选取不同种植年限（2、4、8、12年）人工林生态恢复样地和石漠化对照样地，研究了表层土壤原生动物对人工林生态恢复的响应特征。在本研究的喀斯特样地，共鉴定到土壤原生动物22种，其中鞭毛虫8种，优势类群包括动基体目、金滴目和眼虫目；肉足虫4种，优势类群有变形目和表壳目；纤毛虫10种，优势类群包括下毛目、前口目、肾形目和侧口目。土壤原生动物总数从石漠化样地的1 g干土425×103个，逐渐增加到12年人工林恢复样地的633×103个，年恢复速率为1 g干土17.7×103个。土壤原生动物的类群数从石漠化样地的17种显著增加到12年人工林恢复样地的22种。人工林恢复样地的土壤原生动物丰富度指数（3.10~3.30）显著高于石漠化样地（2.64），平均高出19%~27%；香农多样性指数（2.59~2.77）和均匀度指数（0.86~0.91）随生态恢复的变化不明显。土壤孔隙度、湿度、总有机碳、可溶性有机碳、全氮、速效氮和微生物碳含量均随恢复年限的延长而逐渐增加或升高，其年增长速率分别为3.84%、6.85%、3.89%、11.5%、4.20%、7.13%、24.8%，并与原生动物总数、类群数和香农指数（除了总有机碳与类群数、速效氮与香农指数）均呈显著正相关关系（P<0.01）。本研究表明，土壤原生动物群落大小和多样性对喀斯特生态恢复的响应敏感，与土壤基本肥力形成协同演变，可以作为喀斯特生态恢复的指示生物。