| Biodiversity conservation and ecosystem service in agriculture landscape are attracting extensive attention for they are the basis of agriculture sustainable development in the future.Numerous studies have shown that landscape homogenization which caused by agriculture intensification was an important reason that results in agriculture biodiversity decrease.To improve the landscape pattern and quality are important approaches for biodiversity conservation in agriculture landscape.Although studies on the influence of different landscape elements and pattern on biodiversity had been done abroad,more researches should be done to develop a sound agricultural landscape biodiversity conservation principles and technology.Especially,there was no consistent conclusion on how biodiversity distribution was impacted by landscape composition and vegetation structure.Therefore,this paper analyzed the influence of agro-forestry system on carabid diversity,the influence of remainder and new-built semi-natural habitats on carabid and spider diversity,the influence of landscape structure on carabid and spider diversity and their correlated spatial scales based on the research at five agriculture areas including Fangshan district,Shunyi district and Miyun district,Beijing city,Quzhou,Heibei province,and Qianjiang,Hubei province under three study scale including inner-field scale,between-field scale and landscape scale.The study main included the effects of landscape pattern spatial scale,habitat type,crop planting mode on the distribution of carabid and spider.Insects were collected using pitfall traps.The main conclusions are as follows:(1)At inner-field scale,the study detected the agro-forestry system in Fangshan district.The diversity of carabid was compared between walnut planting system(walnut monoculture system,walnut-chrysanthemum intercropping system)and natural habitats(temperate deciduous forest,alpine meadow).The results showed:1)in 2011 and 2012,the walnut planting system maintained comparative activity density of overall carabid and species richness of large carabid with natural habitats.However,in 2012,the walnut monoculture system maintained a significantly higher level of species richness of overall carabid while the activity density of large carabid was significantly lower in walnut-chrysanthemum intercropping system;2)the composition of overall carabid and large sized carabid in walnut monoculture system and walnut-chrysanthemum intercropping system were similar but different with natural habitats;and 3)the carabid distribution was determined by the soil properties.High pH value and P content will lead to a significant decrease in large sized carabid.Therefore,although more monitoring should be done,our study showed that argo-forestry system could be regarded as an important way for biodiversity conservation during the development of mountainous areas.(2)At between-field scale,the distribution pattern of carabid and spider were compared at Quzhou,Shunyi and Qianjiang.The distribution of carabid diversity was compared between farmland and field margin at Quzhou County,both 1997 and 2014.The results showed:1)the species richness of study area in 2014 was much higher than that in 1997;2)in 2014,the species richness at the field margin was significantly higher than inner field;3)the carabid composition in 2014 and 1997 presented a distinct heterogeneous;4)the Soil nitrogen content determined the carabid composition in 1997.The results indicated that though the cereal production was significantly increased because of the successfully desalinization,the enemy diversity was greatly decreased because of the intensification and simplification of agricultural landscape.However,the remainder semi-natural habitat played an important role in maintaining carabid diversity.Also,the distribution pattern of carabid and spider were compared at typical cropland and semi-natural habitat at Qianjiang district.The result showed:1)the remainder dam grass land and woodland maintained a significantly higher level of spider abundance,while the carabid species richness was significantly lower in dam grass land than in woodland;2)during May to September,2013,the carabid and spider diversity changed in a fluctuating way.For the carabids,the species richness peaked at cropfield in June while peaking at semi-natural habitats in May.For spiders,the highest species richness appeared at cropfield in September and at semi-natural habitats in June.These indicated that:the residual semi-natural habitat in the landscape is of great significance to maintain the natural enemies of spiders.The study on Shunyi district discussed the influence of newly built grassy strip,woodland and natural grassy margin on the distribution of carabid and spider diversity.Moreover,the influence of vegetation structure of field margin on carabid and spider composition was discussed here.The results showed:1)the Alpha diversity of carabids,spiders and aphids were significantly higher in wheat fields adjacent to woodland.Meanwhile,there was a relatively higher enemy-aphid ratio in wheat fields with woodland and newly created field margins;2)in terms of the distribution of enemy composition,there was a high similarity of carabid composition in the wheat field adjacent to the artificial grass belt;and the spider composition was highly similar in wheat field with woodland margins;3)vegetation structure determined the distribution pattern of carabid and spider community composition;4)the activity density of carabid and spider was significantly higher in field margin than inner field.The results indicated that newly created semi-natural field margin could significantly improve the enemy diversity and pest biological rate in agricultural landscape.Semi-natural field margins with complex vegetation structure can maintain relatively higher enemy diversity.The diversity of carabid and spider were significantly higher in semi-natural field margin than adjacent crop field.The results indicated that semi-natural could significantly increase enemy diversity and the efficiency of pest bio-control of adjacent crop field through "spill-over" effect.(3)At landscape scale,the influence of landscape composition on carabid and spider was analyzed.At Qianjiang district,the study compared the distribution of carabid and spider on typical farmland and semi-natural habitat.Meanwhile,the influence of landscape composition on carabid and spider distribution was discussed at the scale of 251 m radius.The result showed:increasing the proportion of semi-natural habitats and landscape diversity can significantly decrease the diversity of the carabids and increase the diversity of spiders at 251m radius landscape scale.Therefore,the landscape construction for the purpose of enemy conservation needs to be carried out based on the varied responses to the landscape context.For the study at Miyun district,the response spatial scale and mechanism of carabid to landscape composition were discussed.Also,the impact of vegetation structure of semi-natural habitat on carabid distribution was detected.The results showed:1)the abundance of carabid was significantly lower at woodland;2)the carabid composition was determined by habitat types instead of landscape complexity.Maize fields maintained a significantly similar carabid composition,so did woodland.However the composition in natural habitat was highly heterogeneous;3)at the spatial scale between 100 m and 200 m,increasing the percentage of semi-natural habitat would significantly decrease the species richness and individuals of carabid.Woodland with simple vegetation structure goes against the carabid conservation.A fine construction of semi-natural habitat should select advisable vegetation composition to increase the species that could benefit the carabid predatory groups,for example Rehmannia glutinosa and Medicago sativa and so on.(4)Finally,we summarized the synthesize approaches on agriculture pest control.And a guidance of pest biological control and agricultural development was provided. |
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