萘对川西亚高山森林土壤微生物量、丰度和磷脂脂肪酸的影响

萘作为土壤动物化学抑制剂已在土壤动物生态功能的研究中广泛使用,但其非目标效应使其应用仍存在很大的不确定性。为了解在亚高山森林土壤应用萘抑制土壤动物群落的非目标效应,以川西亚高山森林土壤为研究对象,采用微缩实验研究了土壤微生物生物量、丰度和磷脂脂肪酸对萘胁迫的短期响应。结果表明,萘处理和对照的土壤微生物生物量碳(MBC)、真菌丰度以及细菌、真菌、革兰氏阳性菌(G~+)和革兰氏阴性菌(G~-)PLFAs含量在整个培养期间表现为降低的变化趋势,二者的土壤微生物生物量碳和G~+PLFAs含量以培养52d最低,细菌、真菌和G~-PLFAs含量以培养的45d最低。萘处理和对照的微生物生物量氮(MBN)含量表现出先升高后降低的动态,微生物生物量碳氮比(MBC/MBN)则表现为相反趋势。对照的真菌/细菌PLFAs比值呈现先升高后降低的动态,以培养的17d最高,但萘处理的真菌/细菌PLFAs比值无明显变化规律;萘处理的G~+/G~-PLFAs比值表现为降低的变化趋势,对照的G~+/G~-PLFAs比值表现为先降低后升高的趋势。萘处理仅显著影响了G~+/G~-PLFAs比值,但萘处理和采样时间的交互作用显著影响MBC/MBN、细菌丰度、真菌/细菌丰度比以及细菌、真菌的PLFAs含量、真菌/细菌PLFAs比值、G~+/G~-PLFAs比值。萘作为土壤动物抑制剂对川西亚高山森林土壤微生物群落的非目标效应具有时间变异性。

Effects of naphthalene on soil microbial biomass, microbial abundance, and microbial phospholipid fatty acids in a subalpine forest of western Sichuan

As a biocide of soil fauna, naphthalene has been widely used in the study of the ecological functions of soil fauna; however, their effect on non-target organisms has raised doubts about its widespread application. The present study was conducted in order to determine whether there are non-target effects of naphthalene in the soil of subalpine forest in the west Qinghai-Tibet Plateau. The short-term responses of soil microbial biomass, microbial abundance, and microbial phospholipid fatty acids (PLFAs) to naphthalene were studied in microcosms. The results showed that the soil microbial biomass carbon (MBC), fungal abundance, and the contents of bacteria, fungi, gram-positive bacteria (G⁺), and gram-negative bacteria (G^-) PLFAs were reduced during the entire study period. The lowest MBC and G⁺ PLFAs contents in both the no-naphthalene and naphthalene microcosms were observed at the end of culture (52 days), and the lowest bacterial, fungal, and G^- PLFAs contents in both microcosms were observed at 45 days after application of naphthalene. The content of microbial biomass nitrogen (MBN) in the naphthalene and no-naphthalene microcosms showed increased and decreased dynamics during the entire study period, and the highest MBN in both microcosms were observed at 17 days after application of naphthalene, but reverse dynamic changes were observed for the ratio of MBC/MBN. The ratio of fungi/bacterial PLFAs in the no-naphthalene microcosm showed decreased and increased dynamics during the entire study period, and the highest fungi/bacterial PLFAs were observed at 17 days after application of naphthalene, whereas little change was detected in the naphthalene microcosm. The ratio of G⁺/G^-PLFAs in the naphthalene microcosm was reduced during the entire study period, but showed increased and decreased dynamics in the no-naphthalene microcosm during the entire study period. Naphthalene treatment only significantly affected the ratio of G⁺/G^-PLFAs, whereas the interaction of naphthalene treatment and sampling time had significant effects on the MBC/MBN ratio, bacterial abundance, fungi/bacterial abundance, PLFA content of bacteria and fungi, ratio of fungi/bacterial PLFAs, and G⁺/G^- PLFAs ratio. In the short term, the non-target effects of naphthalene as a biocide to reduce soil fauna abundance may have a temporally variable influence on soil microbial communities in the subalpine forests of western Sichuan.