北方常见农业土地利用方式对土壤螨群落结构的影响

Effect of agricultural land use types on soil mite communities in north China

土壤螨群落与土壤健康状况密切相关,农业土地利用方式会影响土壤螨的生存环境,进而影响螨的群落分布。在北方传统农业区研究了小麦玉米常规轮作农田,1年温室蔬菜大棚、4年温室蔬菜大棚和4年露天菜地下土壤主要理化指标和螨群落结构。研究结果表明露天菜地和温室大棚的利用方式均会提高土壤碱解氮和有机质含量,同时温室大棚的长期利用会增加土壤有效磷含量。螨群落分析显示常规农田中甲螨亚目为优势类群;常规农田转变为温室大棚后,由于施肥造成土壤营养物质含量增加,以及人类对土壤扰动程度的提高,无气门亚目取代甲螨亚目成为温室内螨优势类群。但随着温室年限的延长,螨多样性和粉螨科丰度都要有所下降,这可能是磷累积和强扰动效应的共同后果。常规农田转变为露天菜地后,加强的人类扰动也会降低甲螨亚目丰度,但与温室螨群落相比,4个亚目分布要相对均匀。温室在3种土地利用类型中对土壤螨的负面影响最为明显,从土壤功能的自我维持和修复方面来讲是十分不利的,温室内土壤生物多样性的保护尤其值得人们关注和重视。

Soil health is closely related to the soil mite community.Land use types can alter the soil environment,which could further influence soil biodiversity,including that of soil mites.Soil mites are important indicators of soil condition and anthropogenic impact.In order to explore the relationship between soil mites and agricultural land use types,an experiment was conducted in a traditional agricultural region of north China.Four treatments were included： a routine winter wheat-summer maize rotation field,a one-year vegetable plastic greenhouse,a four-year vegetable greenhouse and a four-year open vegetable field.Each treatment was replicated three times.In May and October 2012,the soils were sampled to evaluate the changes in soil physico-chemical parameters as well as the abundance,diversity and community structure of the soil mites.Mite diversity was tested using the Shannon-Wiener index and taxonomic richness,and a canonical correspondence analysis（CCA） was used to elucidate the relationship between the soil mite community,the soil physico-chemical parameters and the treatments.The results indicated that the open vegetable field significantly increased the hydrolyzable nitrogen content and the four-year vegetable greenhouse increased the available phosphorus content.The average mite abundances from each plot were 22568 ind/m2 in May and 20155 ind/m2 in October.A total of thirty-six soil mite taxon groups were identified.Acaridae were the most abundant at 39%.Other dominant mite taxa included Tarsonemidae,Pygmephoridae,Microdispidae,Laelapidae,Ascidae,Mesostigmata nymph,Scheloribates sp.,Tectocepheus velatu,Oppiella sp.,Oppia sp.1,Protoribates sp.and oribatid juveniles.These dominant taxa accounted for 91% of mite abundances.The soil mite community analysis showed that Oribatid mites were dominant in the routine agricultural field.From the routine field to the greenhouse,the r-strategic Astigmata,especially the Acaridae,became the dominant assemblage over the K-strategic oribatid mites,which could be attributed to the increase in fertilizer input and human disturbance.The succession was obvious in the new built one-year vegetable greenhouse treatment.However,the mite diversity and Acaridae abundance decreased after the greenhouses were used for four years,which suggested that the accumulation of phosphorus and the more frequent disturbance were unfavorable conditions for the soil mite community.Disturbance also decreased the abundance of Oribatida,Pygmephoridae and Microdispidae.From the routine field to the open vegetable field,management led to a decrease of Oribatida with the four suborders having a similar proportion in the open vegetable field.Compared with the vegetable greenhouses,the open vegetable field had a more equable distribution of the four treatments.In summary,the most serious disturbance and the highest loss of mite diversity occurred in the vegetable greenhouses,compared with the other two land use types.This loss of mite diversity could destroy soil fertility maintenance and self-restoration and have a negative impact on sustainable agricultural productivity.Therefore,although greenhouses can increase yield and income,we should pay more attention to the protection of soil biodiversity in future,especially of the mite community.