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增温和降雨减少对杉木幼林土壤酶活性的影响

江淼华1,2,倪梦颖2,3,周嘉聪2,3,陈岳民2,3*,杨玉盛2,3   

  1. (1闽江学院海洋学院地理科学系, 福州 350108;2湿润亚热带山地生态国家重点实验室培育基地, 福州 350007;3福建师范大学地理科学学院, 福州 350007)
  • 出版日期:2018-11-10 发布日期:2018-11-10

Effects of warming and precipitation reduction on soil enzyme activity in a young Cunninghamia lanceolata plantation.

JIANG Miao-hua1,2, NI Meng-ying2,3, ZHOU Jia-cong2,3, CHEN Yueh-min2,3*, YANG Yu-sheng2,3   

  1. (1Department of Geography, Ocean College, Minjiang University, Fuzhou 350108, China; 2Cultivation Base of State Key Laboratory of Humid Subtropical Mountain Ecology, Fuzhou 350007, China; 3School of Geographical Sciences, Fujian Normal University, Fuzhou 350007, China).
  • Online:2018-11-10 Published:2018-11-10

摘要: 土壤酶在土壤过程中扮演着一个重要的角色,其通过参与凋落物和土壤有机质的分解过程从而驱动着土壤养分循环和碳循环,而影响这个过程的因素很多,主要包括温度和土壤含水量。本研究在中亚热带杉木人工幼林进行对照、增温、隔离降雨以及增温+隔离降雨联合处理实验,探究温度和水分变化对土壤胞外酶活性的影响,包括参与碳循环的β-葡萄糖苷酶(βG)、纤维素水解酶(CBH)、酚氧化酶(PHO)、过氧化物酶(PEO),和参与氮循环的β-N-乙酰氨基葡萄糖苷酶(NAG)以及参与磷循环的酸性磷酸酶(AP)。结果表明:增温和隔离降雨以及两者的交互作用使土壤含水量、微生物生物量氮、可溶性有机氮和可溶性有机碳(DOC)显著下降(P<0.05)。此外,增温显著增加了铵态氮(NH4+-N)和硝态氮含量(P<0.05),以及βG、CBH和NAG酶活性(P<0.05);隔离降雨在一定程度上对βG、CBH和NAG(P<0.05)酶活性起到促进作用;而增温+隔离降雨处理下,βG、CBH、NAG、PHO、PEO酶活性都略微上升(P>0.05);AP酶活性在各个处理后均剧烈下降(P<0.05)。冗余分析结果显示,全氮、NH4+-N和DOC是驱动土壤酶活性变化的主要影响因子。研究表明,参与碳、氮循环的土壤酶在温度升高和降水减少下响应较为积极,酶活性有所上升,从而加速了土壤碳分解,但参与磷循环的土壤酶活性却显著下降,未来该地区的磷限制情况将进一步加剧。本研究将为未来气候变暖和降水减少下对预测养分循环和碳循环提供一定的科学依据。

Abstract: Soil enzyme plays an important role in soil processes, which drives soil nutrient and carbon cycling by participating in the decomposition process of litter and organic matter. However, there are many factors affecting the decomposition process, including temperature and soil moisture. In this study, we examined the effects of warming, precipitation exclusion, and their combined treatment on soil extracellular enzyme activity in a mid-subtropical young Cunninghamia lanceolata plantation. These extracellular enzymes included carbonacquisition enzymes (β-glucosidase, βG; cellulose hydrolase, CBH; phenol oxidase, PHO; peroxidase, PEO), nitrogen acquisition enzyme (β-N-acetylglucosaminidase, NAG), and phosphorus acquisition enzyme (acid phosphatase, AP). The results showed that the soil moisture, microbial biomass nitrogen, dissolved organic nitrogen, and dissolved organic carbon (DOC) were significantly decreased by warming, precipitation exclusion, and their interaction. Warming significantly increased the concentrations of ammonium (NH4+-N) and nitrate, and the activities of βG, CBH, and NAG (P<0.05). Precipitation exclusion enhanced the activities of βG, CBH and NAG to some extent. The activities of βG, CBH, NAG, PHO, and PEO increased slightly under the treatment of combined warming and precipitation exclusion (P>0.05). The activity of AP decreaseddramatically in all the treatments (P<0.05). Results from the redundancy analysis indicated that total nitrogen (P=0.002), NH4+-N (P=0.002), and DOC (P=0.03) concentrations were the main factors driving the changes in soil enzyme activity. Our results indicated that soil enzymes involved in carbon and nitrogen cycling positively responded to warming and precipitation exclusion. Increased enzyme activities accelerated soil carbon decomposition. However, the enzyme activities involved in phosphorus cycling significantly decreased, which could induce phosphorus limitation in this ecosystem in the future. Our results have implications for better understanding of carbon and nutrient cycling under the scenarios of increasing temperature and altering precipitation.