| Jiangxi farmland uses the distribution of " Six mountains,one water,two fields,one road and manor",with excellent and unique farmland landscape ecological resources.The distribution of farmland utilization in Jiangxi Province has a typical characteristic of "six mountains,one water,two fields,one road and manor",with excellent and unique regional farmland landscape ecological resources.Many farmlands are distributed in hilly and mountainous areas,and the surrounding farmland is often accompanied by a high proportion of forest habitat.The farmland landscape in the whole region varies from complex to simple,and the diversity level of farmland landscape is significantly different.After winter crops were harvested,the species composition and quantity of both pests and natural enemies changed greatly.In this study,we focused on the effects of gradient proportion farmland habitat conditions on spider and carabid in winter,the response mechanism of species and richness of spider and carabid to different farmland landscape background and their correlation with various landscape factors were systematically analyzed,and clarified the types and diversity of predatory natural enemies on the surface of fallow rice fields and rape fields in winter.To this end,based on our 20 typical small-scale agricultural landscapes in Nanchang,Yichun,Jiujiang,Fengcheng,we conducted research on the impact of landscape patterns on spider and carabid’ biodiversity.1.Diversity of spider and carabid in different farmland landscapesThe arthropods were sampled,identified and analyzed by pitfall traps to evaluate the species diversity and richness of spider and carabid communities.Differential(the research objects are fallow rice fileds)analysis of the spider and carabid of rice fields.The results showed that there were no difference between the spider biodiversity index,only the sample Laojixiongjia(JX)was significantly lower than the sample Liufangcun(SF),Shanglin(SL).The species richness index indicated that there was no significant difference between other places.Because the fallow rice spider still returned to the fields after the rice has been harvested,but the species did not change much.In the survey of carabid found that there were 5 samples received only one carabid,and its biodiversity index and richness index were 0.The variation of the species rich index of carabid was large,Fangjialaoji(FJ),Shangxin(SX),and Zhoushangminjia(ZS)species richness index significantly below the samples Guanli(GL),Xiangfangcun(FC).The carabid of diversity index was large,and the samples Shangxin(SX),Zhoushangminjia(ZS)were significantly lower than the places Guanli(GL),Shishangcun(SC).2.Effects of different farmland landscape patterns on spider distribution dynamicsBy surveying the distribution of spider populations throughout the winter,we found that:the Ummeliata insecticeps,the Erigone prominens,the Singa pygmaea,the Pardosa,the Piratula procurva,the Enoplognatha diodonta,and the Pardosa pseudoannulata,accounted for 93.05% of the total number of spiders,and the rest of the spider species were unknown.Through the analysis of spider activity density and species in 20 fallow rice fields,it was found that there was no significant difference in spider activity density among different areas,but there was a significant difference in spider species(P=0.02).In addition,it was found that High-Standard Farmland improvement near the test sample land would significantly reduce spider activity density and species.By comparing the spider population density and species analysis in 8 rape fields and 8 rice fields under the same farmland landscape background,it was found that the spider activity density in 5 rice fields was significantly higher than that 5 rape fields,and the spider species in 1 rice field was significantly higher than that 1 rape field.There was a great difference in spider activity density among different rape fields,but there was little difference in spider species.The species diversity and species richness index of spider were positively correlated with the proportion of fallow land(Unused land %)and landscape Shannon-wiener index,and negatively correlated with the proportion of building land(Construction land %)under a given landscape radius.There were 7 dominant species of spiders in the survey,based on the correlation analysis of dominant species spiders and landscape background parameters,it was found that the existence of fallow land significantly affected the activity density of spiders in 6 kinds of farmland landscape parameters,but the responses of different dominant species spiders were different at different landscape scales.There was a significant negative correlation between the dominant spiders and the proportion of building land.In addition,after winter crop was harvested,the proportion of orchard and woodland also significantly affected the spider activity density,among which,the proportion of orchard and forest significantly positively affected the spider activity density,indicating that winter orchard may provide spiders with winter habitat and food resources needed to maintain their life.There was a complementary relationship between spiders’ activity density and different landscape coefficients,which indicated that landscape factors acted in a complementary way.3.Effects of different farmland landscape patterns on carabid distribution dynamicsBy surveying the distribution of carabid populations throughout the winter,we found that: Agonum chalcomus,Pterostichus liodactylus,the two dominant species of carabid accounted for 73.13% of the total number of carabid samples.Through the analysis of carabid activity density and species in 20 fallow rice fields,it was found that there were significant differences(P<0.01)in the activity density of carabid in different fields and species of carabid among different samples(P<0.01).By comparing the carabid population activity density and species analysis in 8 rape fields and 8 rice fields under the same farmland landscape background,it was found that the activity density of carabid in 2rape fields was significantly higher than 2 rice fields,and the species of carabid in 1 rape field was significantly higher than 1 rice fields.In two rape fields,because the sampling times were less than those of the other plots and the sampling period was late winter,the activity density and species of carabid in rice fields were higher than those in rape fields.There was little difference in the activity density of carabid in different rape fields,and was also no difference in the species of carabid.At a specific landscape scale,the species diversity of carabid was significantly positively correlated with the proportion of grassland(Grassland %),and negatively correlated with the proportion of building land(Construction %).There was a significant positive correlation between species richness and fallow land proportion(Unused land %),and a significant negative correlation between species richness and building land proportion(Construction %),landscape Shannon-wiener index(Shannon%)and grassland proportion(Grassland %).As a typical biological indicator species,the response to the semi-natural habitat around cropland after its habitat was destroyed,the density and species of carabid will change accordingly.We also found that forest is a kind of habitat where the carabid tendency was active,there was also a significant positive correlation between the proportion of orchard and grassland with Agonum chalcomus,there was a significant positive correlation between activity density and fallow land area in early winter,and a significant negative correlation between activity density and fallow land area in late winter.The reason was that the early stage of carabids were active frequently,and they often went back and forth to forest,orchard,grassland and fallow land to search for supplementary resources,and the temperature was suitable,the population of carabid in the central field was closely related to the non-crop habitat.However,in late winter,the activity of carabid species decreased,the pests and other alternative prey were missing in the central plot,and most of the species chose to settle in the non-crop habitat,which led to the decrease of the number and species of the central plot.In this study,we systematically investigated the population distribution,richness and species diversity of spider and carabid in winter rice fields and rape fields by pitfall traps,and further clarified the activity rules,population richness and diversity of overwintering natural enemies.At the same time,to explore the winter farmland landscape of fallow rice spider and carabid on the influence of the population,this paper use 20 small-scale farmland landscape around Jiangxi area technical means such as GPS,Arc GIS and multiple regression analysis and other analysis method,comprehensiving analysis the responses of spider and carabid populations to winter landscape patterns,under different small-scale farmland landscape,which providing a theoretical basis for natural enemy control under different small-scale farmland landscapes. |
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