亚热带树种的菌根和根外菌丝对土壤氮矿化及酶活性的影响

doi:10.13287/j.1001-9332.202305.016

摘要/Abstract

摘要： 丛枝菌根(AM)真菌与植物共生促进土壤氮有效性,但菌根和根外菌丝对氮矿化的作用机制还不明确。本研究选择亚热带3种AM树种——杉木、木荷和枫香为对象,采用内生长芯法开展原位土壤培养试验,研究菌根(吸收根和菌丝)、菌丝(无吸收根)及对照(无吸收根和菌丝)处理下土壤理化性质、净氮矿化速率及与有机质分解相关的4种水解酶[亮氨酸氨基肽酶(LAP)、β-N-乙酰葡糖胺糖苷酶(NAG)、β-1,4-葡萄糖苷酶(βG)和纤维素水解酶(CB)]和2种氧化酶[多酚氧化酶(POX)和过氧化物酶(PER)]活性的变化。结果表明: 菌根处理显著影响土壤总碳和pH,对氮矿化速率和所有酶活性均没有显著影响;树种显著影响净氨化速率、净氮矿化速率及NAG、βG、CB、POX和PER活性,其中杉木林的净氮矿化速率和酶活性显著高于2个阔叶树种;菌根处理和树种的交互作用对土壤理化性质、酶活性、净氮矿化速率均没有显著影响。相关性分析表明,pH与除LAP外的5个酶活性呈显著负相关,铵态氮含量、有效磷含量、βG、CB、POX和PER活性与净氮矿化速率存在显著相关性。总体来说,在一个生长季的培养周期内,3种亚热带树种根际和根外菌丝际的土壤酶活性和氮矿化速率没有显著差异。碳循环相关酶与土壤氮矿化速率密切相关,树种在凋落物质量和根系功能性状上的差异通过有机质输入及对林地环境的塑造等方式影响了土壤酶活性和氮矿化过程。

关键词: 菌丝际, 氮有效性, 养分限制, 根系分泌物, 土壤有机质

Abstract: Through symbiosis with plants, arbuscular mycorrhizal (AM) fungi effectively improve the availability of soil nitrogen (N). However, the mechanism through which AM and associated extraradical mycelium affect soil N mineralization remains unknow. We carried out an in situ soil culture experiment by using in-growth cores in plantations of three subtropical tree species, Cunninghamia lanceolata, Schima superba, and Liquidambar formosana. We measured soil physical and chemical properties, net N mineralization rate, and the activities of four kinds of hydrolase (leucine aminopeptidase (LAP), β-1,4-N-acetylglucosaminidase (NAG), β-1,4-glucosidase (βG), cellobiohydrolase (CB)) and two kinds of oxidases (polyphenol oxidase (POX) and peroxidase (PER)) involved in soil organic matter (SOM) mineralization in treatments of mycorrhiza (with absorbing roots and hyphae), hyphae (hyphae only), and control (mycorrhiza-free). The results showed that mycorrhizal treatments significantly affected soil total carbon and pH but did not affect N mineralization rates and all enzymatic activities. Tree species significantly affected net ammonification rate, net N mineralization rate and activities of NAG, βG, CB, POX and PER. The net N mineralization rate and enzyme activities in the C. lanceolata stand were significantly higher than that in monoculture broad-leaved stands of either S. superba or L. formosana. There was no interactive effect of mycorrhizal treatment and tree species on any of soil properties, nor on enzymatic activities or net N mineralization rates. Soil pH was negatively and significantly correlated with five kinds of enzymatic activities except for LAP, while net N mineralization rate significantly correlated with ammonium nitrogen content, available phosphorus content, and the activity level of βG, CB, POX, and PER. In conclusion, there was no difference in enzymatic activities and N mineralization rates between rhizosphere and hyphosphere soils of three subtropical tree species in the whole growing season. The activity of particular carbon cycle-related enzymes was closely related to soil N mineralization rate. It is suggested that differences in litter quality and root functional traits among different tree species affect soil enzyme activities and N mineralization rates through organic matter inputs and shaping soil condition.

Key words: hyphosphere, nitrogen availability, nutrient limitation, root exudate, soil organic matter

陈月鹏, 李石开, 安波, 朱勇, 邹汉鲁, 崔松祥, 付宏燕, 毛瑢, 张芸. 亚热带树种的菌根和根外菌丝对土壤氮矿化及酶活性的影响[J]. 应用生态学报, 2023, 34(5): 1235-1243.

CHEN Yuepeng, LI Shikai, AN Bo, ZHU Yong, ZOU Hanlu, CUI Songxiang, FU Hongyan, MAO Rong, ZHANG Yun. Effects of arbuscular mycorrhizae and extraradical mycelium of subtropical tree species on soil nitrogen mineralization and enzyme activities[J]. Chinese Journal of Applied Ecology, 2023, 34(5): 1235-1243.

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