Insect Diversity In The Typical Forest Stands Of The Water-soil Erosion Controlled Area At Changting

Insect is an indispensable component of forestry ecosystem,its diversity is of great significance to the maintenance of the ecological balance of forestry.Changting is located in the west of Fujian,it’s typical red soil area in southern China.For a long time,due to the severe artificial interference,led to the decrease of the vegetation diversity,further aggravated water-soil erosion problems,it became one of the most serious water-soil erosion at one time in the red soil area,south of China.As government departments step up their governance,the situation of water-soil erosion of Changting was obviously improved,the vegetation conditions and diversity of species were gradually recovering in recent years,however,there were also existed some problems such as the lack of diversity of species and the structure of forest is single.Therefore,plan to take the methods which combining setpoint investigation and sample area investigation,take the 4 most typical forest stands in water-soil erosion area at Changting as research objects.Collected specimen by the means of sweeping method,sexual attraction,light attraction,food attraction,feeding,investigating the diversity of different forest insects system-atically,designed to pinpoint insect species and groups structure of different forest stands,species of main pests and the occurrence of them,the species of main resource insects and their potential value of utilization.Further,it will be provided the basis for the assessment of ecological environment in water-soil erosion area,prevention and management of forestry insect pests,utilization and protection of insect resources,the reform of forest stands for pure Pinus massoniana Lamb forest,optimization of business mode for economic forest,construction and maintenance of water-soil conservation forest and ecological forest,and provides the reference for the planning and maintaining of ecological tourism.The concrete results of the research are:There were 518 species of insect were identified which belong to 153 families 17 orders in the typical forest stands of the water-soil erosion area at Changting,Lepidoptera,Coleoptera,Hemiptera,Hymenoptera,Diptera have 97 families,350 species,it accounts for 63.40%of the total families and 67.58%of the total species of insect in the typical forest stands of the water-soil erosion area at Changting,the 4 orders were dominant insect species.In terms of functional group,phytophagous group(261 species,50.4%)was the most,more than 50%of all insect species.In terms of time frame,The abundance index of insect species was seasonal observably.Investigation of insect diversity in the 4 typical forest stands at Chan gting water-soil erosion area is very important to monitor the control effe ct of water-soil conservation,the results showed that:(1)There were 15 orders,102 families,213 species of insects in Pinus massoniana Lamb forest,20 of these were dominant species,the typical species were Iridmyrmex anceps Roger,Dendrolimus punctatus Walker,Hylobitelus xiaoi Zhang,for their high Abundance index.Compare different types of Pinus massoniana Lamb forest,the insect diversity of the theropencedrymion forest was the highest,the pure forest was the second,and degradation of bare land was the lowest.It showed that vegetation diversity influences insect diversity strikingly(P<0.01),therefore,in the future,the transformation of Pinus massoniana Lamb forest should be combined with different types of tree species,so as to increase the diversity of vegetation.At the same time,the degradation of bare land was not suitable for many insects inhabit,its still the key of water-soil erosion control.From the perspective of different slopes,the insect diversity of the upper slope was lower than the middle and lower slope,which may be affected by the difference of soil fertility in different slope.(2)C.oleifera was fond of warm and acid soil,it was one of the important tree species in water-soil erosion area at Changting.Research Findings,there were 15 orders,99 families,187 species of insects in the C.oleifera forest,13 of the species were dominant species,the typical species were Casmara patrona Meyrick,Poecilocoris latus Dallas,Andrena sp.for their high Abundance index.Compared with the C.oleifera forest of different ages,8-years-old forest had higher Canopy density,and its insect diversity was significantly higher than that of 2-years-old forest.Therefore,the nurturing and management of the young forest should be strengthened to promote its early closure,so as to enhance its insect diversity and increase the species of pollinating insects in order to achieve the purpose of increasing the harvest.(3)Castanea mollissima was fond of well drained microacid sandy loam and has significant economic value,therefore,it was also one of the fine tree species for controlling water-soil erosion.Investigations revealed that there were 14 orders,87 families,144 species of insects in Castanea mollissima forest,15 of the species were dominant species,the typical species are Dryocosmus kuriphilus Yasumatsu,Odontotermes formosanus,Vespa mandarinia Smith for their high Abundance index.(4)Myrica rubra(Lour.)S.et Zucc was also fond of acid soil and it was also suitable for the specific soil conditions of the water-soil erosion area at Changting.Investigations revealed that there were 10 orders,63 families,101 species of insects in Myrica rubra(Lour.)S.et Zucc forest,14 of the species were dominant species,the typical species were Pyrausta diniasalis Walker,Pantala flavescens Fabricius,Erthesina fullo for their high Abundance index.Based on the relationship between insects and humans,the species of forestry pests which harm forest seriously were Hylobitelus xiaoi Zhang(3121.56hm2),Dendrolimus punctata Walker(1000.50hm2),Casmara patrona Meyrick(33.35hm2),Monochamus alternatus Hope(14.67hm2),Dryocosmus kuriphilus Yasumatsu(3.34hm2).et,mainly to harm Pinus massoniana Lamb,C.oleifera,Castanea mollissima.Common natural enemy insects were 31 species.There were the most species in Pinus massoniana Lamb forest,15 species.Iridmyrmex anceps Roger,Blepharipa zebina Walker,Pantala flavescens Fabricius,Xanthopimpla pedator Fabricius,Harmonia axyridis Pallas,Epicauta ruficeps,Vespa mandarinia Smith,Carcelia matsukarehae were the dominant species.In different types of Pinus massoniana Lamb forest,there were the most species(8 species)of natural enemy insects of theropencedrymion,pure forest were the second(4 species),and degradation of bare land were the least(2 species).There were 6 species of natural enemy insects in C.oleifera forest,Chilocorus kuwanae Silvestri,Blepharipa zebina Walker,Vespa mandarinia Smith,Carelia zebina Walker were the dominant species.In different ages of C.oleifera forest,there were more species of natural enemy insects in 8-years-old C.oleifera forest(4 species)than that in 2-years-old C.oleifera forest(0 species).There were 6 species of natural enemy insects in Castanea mollissima forest,Vespa mandarinia Smith,Drino inconspicua Meigen,Aleiodes sp.,Iridmyrmex anceps Roger,Blepharipa zebina Walker are the dominant species.There were 7 species of natural enemy insects in Myrica rubra(Lour.)S.et Zucc forest,Pantala flavescens Fabricius,Ischnojoppa luteator Fabricius,Vespa ducalis Smith,Coccygomimus disparis Viereck,Coccinella septempunctata were the dominant species.Should be attentived to the rational use of chemical insecticides in order to create a good habitat which was beneficial to protect natural enemies.From the above,the insect species in the typical forest stands of the water-soil erosion area at Changting were increased significantly than degradation of bare land,showed that for a long time of water-soil erosion management not only restored and improved the local vegetation conditions,but also increased the insect diversity,and further verified the ecological effect of the current water-soil erosion control.In different forest types,especially the diversity of insects in theropencedrymion was the highest,it showed that as pioneer tree species,the pure Pinus massoniana Lamb forest has completed the specific stage of the management task at the present stage.In the next stage,should be proceeded with the transformation of the forest,aiming to increase the area and proportion of theropencedrymion in order to increase the diversity of insects.At the same time,different types of economic forest not only had the function of water-soil erosion control,but also it could increase production and income for local farmers,which was worth promoting.However,in terms of operation mode and maintenance management level,scientific guidance is required,should be rational use of chemical insecticides,coordinating the adoption of other prevention and control technologies,aim to reduce the unreasonable human disturbance and increase the biodiversity of the forest,which in turn may also help to further enhance the production and quality of fruits in economic forest,for some resource insects,the research and development should be intensified to maximize the ecological benefit,economic benefit and social benefit.