Study On Ecological Effect Of Kokyar Artificial Shelterbelt System In Aksu

The K kyar Shelterbelt in the peri-urban area of Aksu, Xinjiang is a model projectfor large scale artificial afforestation in regions which suffer from drought and watershortage. As a part of "Three-north shelterbelt forest" system, It plays an active role tosocial, economic and ecological of Aksu city. The study choose five representativeartificial shelterbelt types (Malus pumila, Ziziphus jujube, Pyrus sinkiangensis, Populusbolleana and the mixed forest) in K kyar green project as objects, based on fuzzymathematics, using multi-level fuzzy comprehensive evaluation model of ecosystemhealth, from the plant growth conditions and protective benefits, waterbalance between supply and demand, soil mechanical composition this three aspectscomprehensively evaluate these ecological effect. The results are as follows:1)200cm height, Windbreak efficiency of leeward side show as: The mixed forest(78.55%)> Malus pumila (73.20%)> Pyrus sinkiangensis (72.6%)> Ziziphus jujuba(70.27%)> Populus bolleana(65.73%);The different ages of Populus bolleanashelterbelts show as:22-year stand age>15-year stand age>6-year stand age. Thecontribution of each forest structure factor to windbreak efficiency of50cm height followed: the number of the first grade branch> density> crowndiameter> branch height> ground diameter> tree height. For200cm: crowndiameter> ground diameter> tree height>density> the number of the first gradebranch.2)The soil fine sand content in different vegetation types and different afforestationyears of shelterbelts are the mixed forest and15-year stand age Populus bolleanahighest. From the vertical distribution of soil particle diameter show as: The massfraction (percentage) of coarse sand is decreasing first and then increasing with soillayer increasing, while the mass fraction of soil fine sand (percentage) is increasing firstand then decreasing.3) The soil bulk density in each layer of soil in different afforestation types and years is less than the contrast soil, the improvement of the mixed forest is the best,which reduced0.286g/cm³than the contrast, Ziziphus jujube and Malus pumila takes thesecond place, Populus bolleana and Pyrus sinkiangensis are the worst. The soil bulkdensity in6-year stand age,15-year stand age and22-year stand age respectivelyreduces0.128g/cm³,0.214g/cm³,0.244g/cm³comparing to the contrast soil. Theresult of variance analysis shows that the effect of different afforestation types and yearscontributing to the volume weight of soil is in significant level.4) The effect that different forest types decrease the content of water soluble saltsin soil show as: mixed forest> Malus pumila> Populus bolleana Lauche> Ziziphusjujube> Pyrus sinkiangensis.The reducing effect in15-year stand age is most obviousof different afforestation years, dropping4.2244mg/kg.The content of each ions ofdifferent forest belts shows different variation tendency, of which the content of Cl^-isthe highest in Populus bolleana and Ziziphus jujube sample, Ca²⁺is the highest in Pyrussinkiangensis and SO₄^2-is the highest in Malus pumila and the mixed forest. In differentforest types, the content variation of salt ions overall shows: Cl^->Ca²⁺>SO₄^2->Mg²⁺>K+Na>HCO_<sup>3-. The result of variance analysis shows that the effect ofdifferent afforestation types and years contributing to the content of water soluble saltsboth reach significant level.5) There is close connection in each factor of soil physicochemical property. Soilorganic matter, total nitrogen, total phosphorus, available nitrogen and phosphorus isnegative correlation to soil bulk density and positive correlation to the content of thesoil particle diameter <0.25mm, while soil available potassium is opposite, which ispositive correlation to soil bulk density and negative correlation to the content of thesoil particle diameter <0.25mm, but not reaches the significant level.6) In April, In addition to Pyrus sinkiangensis sample, the range of reducetemperature in other4samples is: Populus bolleana> mixed forest> Ziziphus jujuba>Malus pumila, the temperature of Pyrus sinkiangensis sample is0.4℃higher than contrast, at the same time, the range of reduce temperature in afforestation with differentyeas shows:15-year stand age>6-year stand age>22-year stand age. In August, thereduce range show as Populus bolleana> Malus pumila> mixed forest> Ziziphusjujuba> Pyrus sinkiangensis,22-year stand age>15-year stand age>6-year stand age.The adjustment between air relative humidity and temperature is negatively correlated.In April, the increase range of air relative humidity in different afforestation typespresent as Malus pumila(5.6%)> mixed forest(4.4%)> Pyrus sinkiangensis (4.0%)>Ziziphus jujuba(3.9%)> Populus bolleana(3.6%). In August: Malus pumila (14.7%)>Pyrus sinkiangensis(14.2%)> Ziziphus jujuba(10.7%)> mixed forest(10.2%)>Populus bolleana(7.6%).7) This paper, applying the method of fuzzy mathematics, comprehensivelyassessed the ecosystem health of five different kinds of species in K kyar shelterbelts.The results show that: mixed forest and Malus pumila sample belong to Y1(healthy);Pyrus sinkiangensis belongs to Y2(sub-healthy); Ziziphus jujube and Populus bolleanabelongs to Y3(unhealthy). The shelterbelts species with good ecological efficiency areevaluated as healthy types, and suitable for the local application; Sub-healthy specieshave less ecological benefit; Unhealthy types which have relatively poor ecologicalbenefit are with low application value.Research outputs of this paper can be a foundation for the ecological evaluation ofK kyar shelterbelts, and can provide scientific basis for further greening projects ofAksu city. This can help to achieve the goals of reducing sandstorm hazards, improvingair quality and more effectively improving the living environment of all ethnic groupsin Aksu city.