Scale Effect Of Landuse On The Macroinvertebrates Within River Corridor

In order to strengthen the river riparian management and ecologicalrestoration, on the basis of landscape features of Taizi River in catchmentand different corridor scales and field survey of macroinvertebrates in thewhole basin, we evaluated the relationship between landscape features andcharacteristics of macroinvertebrates. The main results follow:1.In Taizi River, the BI index has significant correlations withlanduse and dissolved oxygen and a good indicator for these two types ofdisturbance. The FBI index could well reflect the acid and ammoniacontamination of the investigated stream. Strong negative correlation wasfound between the ASPT index and several water quality parametersconcerning oxygen consumption. The B-IBI index had a significantnegative correlation with the total nitrogen concentration, being a goodindicator nitrogen contamination. Besides, the B-IBI index was alsosignificantly correlated to disturbance caused by other types of humanactivities and can be used as an indicator for both land use and aquaticpollution. 2.Through analyzing the water quality, the community ofmacroinvertebrates （including community structure, functional feedinggroups） and index of macroinvertebrates （including biodiversity andbiological evaluation index） of in mountainous streams of Taizi River, themain factor that was considered to influence the ecosystem environmentwas the landuse changing in riparian zone, especially the increases offarmland and village ration in the near river region. The main humanactivities impacting on are land use changing in riparian zone, especiallythe increasing proportion of farmland and village near river.（1） Theimpacts on water quality of farmland were mainly in TN and EC, when thebuffer width is25m, the explaining of farmland area to TN is highest;when the buffer width is100m, farmland has a highest explaining to EC.Village mainly affects water quality on pH, DO, TP, COD_Mnand COD_Cr.The ratio of village area within500m buffer zone has the highestexplaining rate on pH, DO and COD_Mn; for TP and COD_Cr, the explainingrate is decreasing after increasing with buffer width increasing, when thebuffer width is100m, the explaining rate is the highest. Village wasconsidered to influence water quality mainly on pH, DO, TP, COD_MnandCOD_Cr. When the buffer zone was500m, the ratio of village area showedthe highest explaining rate on pH, DO and COD_Mn. When that for TP andCOD_Cr, the explaining rate firstly decreased then increase with theextending of buffer width, during which the buffer width was chosen to be 100m.（2） The main impacts of farmland on community ofmacroinvertebrates were proved to be Plecoptera taxa and the relativeabundance of Plecoptera. The explaining rate of farmland to Plecopterataxa and the relative abundance of Plecoptera was firstly increased andthen decreased with the prolonging of buffer width, and the highestexplaining rate of buffer width was determined to be100m. However, therelationship between village and macroinvertebrates was relatively weak,and the primary influential factor was total individuals, Plecoptera taxa,relative abundance of Plecoptera and relative abundance of scrapers. Forthe total individuals, the explaining rate of village increased with theenhancing of buffer width; and the highest explaining rate was determinedat buffer width being500m. The explaining rate of village to Plecopterataxa, the relative abundance of Plecoptera and the relative of scrapersfirstly increased and then decreased with the prolonging of buffer width.When the width at the range of100²00m far from the channel, thevillage showed the highest explaining rate.（3） For the index ofmacroinvertebrates, the farmland mainly affects ASPT index and BI index.The interpretation of the ASPT index decreased with the increasing ofbuffer width, during which the buffer width was explained to be25m withthe explaining rate being the highest. The explaining rate of farmland toBI index was firstly increased and then decreased with the prolonging ofbuffer width, and the highest explaining rate of buffer width was100m. In summary, in order to reduce the impact human activities （farmlandand villages） on water quality and aquatic ecosystem, there are mainly twosuggestions for the management of landuse in riparian zone ofmountainous streams in Taizi River:（1） Farmland should be prohibited inthe buffer zone with the width less than25m far from stream channel, andthat of village should be200m;（2） In buffer zone with100m away fromstream, farmland should be strengthened in management, and villageshould be reasonable planning in the range of200⁵00m.