Effects Of Mulch On The Micro-ecological Environment Of Urban Green Space

Mulch is a kind of organic covering,which is made by the solid waste from the waste wood of city afforestation and furniture through the process of microbial fermentation,dyeing,the addition of inflaming retardant,etc.Mulch is also an ideal paving material which can be used in the building of sponge city.By covering the bare soil,mulch may not only play a role in sucking dust,reducing the flowing dust,regulating soil temperature,increasing soil fertility,improving soil water content,but also delaying soil erosion,absorb environmental noise,etc.It has certain adjustment functions in the micro-ecosystem of green space.Much has been researched and applied abroad for many years,but in the urban ecological environment of our country,whether mulch can play a corresponding role is still rarely studied.To deeply study the influence of mulch on the micro-environment of urban green space,two experiments--open green space experiment and controlled experiment,are designed in this research.In controlled experiment,three different covering thickness and one no covering experiment are set up to study the changes in soil moisture,permeability,temperature,nutriture and the quantity of culturable microorganism in shallow soil.In the open green space experiment,open park green areas were selected,and two kinds of test treatments covering mulch and non-covering blanks were conducted to study the soil moisture content,temperature,permeability,erosion amount,weeds,and nutrient status of different soil depths and the quantity changes of culturable microorganism and the variation of environmental noise.Through more than one year of continuous observation and research,it shows that:(1)There was a difference between soil temperature covered by mulch treatment and no mulch.The results of open green space experiment and controlled experiment were basically consistent.In summer,the average soil temperature in open green space covered with mulch was 27.74?,which is lower than the no covered(28.58?).The maximum soil temperature with mulch treatment was 30.15?,lower than the soil temperature in non-covering(32.16?),indicating that the paving of mulch played a better cooling effect.In winter,the average soil temperature in open green space covered with mulch was 1.12?,which was 2.16 higher than that of non?-covering(-1.04°C).The minimum soil temperature with mulch was 0.16?,2.29 ?higher than the non-covering.It means that Mulch has a good effect on keeping warm.Mulch treatment covering has a dual temperature effect,which reduces the fluctuation amplitude and fluctuation rate of soil temperature and maintains the relative stability of soil temperature.(2)There are obvious differences of the soil hydrological characteristics between covered and the no covered.In the non-covering experiment,with the increase of the thickness of mulch paving,the annual mean value of soil water content also increased.The specific value was covered with 9cm mulch(35.65%)>covered with 6cm mulch(29.10%)>covered with 3cm mulch(25.44%)>non covered(18.98%).In open green space experiment,the moisture content of soil covered with mulch was also higher than the non-covering and mulch showed excellent water retention characteristics.Covered with mulch increased the soil permeability coefficient,which was more pronounced in shallow soils With the increase of soil depth,the effect of cover treatment on soil permeability coefficient is getting smaller and smaller.Mulch treatment significantly reduced the amount of soil erosion.The amount of soil wind erosion with mulch covering treatment was 1.43 t·hm-2,about 1/6 of that of non-covering(9.15 t·hm-2).The water erosion of the soil with mulch covering treatment was also significantly lower than that of the non-covering.(3)The effect of covering mulch on soil physicochemical properties is obvious.Covering mulch increased the contents of soil available Nitrogen and available Kalium and had little influence on soil available phosphorus.With the extension of covering time,the decomposition rate of mulch also gradually increased.Paving mulch obviously improved soil organic content and buffer ability of the soil.The soil organic matter for different treatment of covering thickness,covering 9 cm mulch > covering 6 cm mulch > covering 3 cm mulch>non-covering.The effect of mulch covering treatment on soil p H value was small,but mulch covering treatment reduced the rate of decrease of soil p H value.(4)Mulch covering treatment increased the contents of soil microorganism,significantly increased the number of soil bacteria and fungi,while it had a relatively small impact on soil actinomycetes.Increasing the mulch paving thickness can increase the contents of soil microorganism to some extent.In open green space experiment,mulch increases the contents of soil bacteria in the 10-20 cm depth,but it has less influence on 0-10 cm shallow soil.Mulch increases the contents of soil antinomycetes,but the contents of antinomycetes in different soil depth are nearly the same.Mulch covering treatment can increase the contents of soil fungus.Soil fungus in 0-10 cm shallow soil has the larger number.(5)The coverage and biomass of weeds treated with mulch were significantly lower than that of non-covering.In the initial period,weed coverage in mulch paving treatment was 15%,far less than that of 100% in the non-covering.Weeds cannot grow.With the increase of paving time,the difference in mulch treatment covering and noncovering is shrinking,and the inhibitory effect of mulch on weeds was reduced.(6)The paving of mulch can eliminate the noise in the city.When paving thickness is 9 cm,and paving area is 4 m2,the noise decibel with the noise reduction of mulch will be 17.7 d B lower than the non-covering.And the amplitude in the experimental sound wave was lower.Spectrogram and histogram were in the same condition.