| Plant growth needs a stable and suitable microhabitat in degraded site.In order to study the microhabitat improvement techniques for drought and steep slopeland in Loess Region of Western Shanxi,we investigated the plantation under different site preparation modes in Dongcheng Jixian County and carried out reforestation test including different mulching measures,different dosages of water retaining agent and different infiltrating irrigation aperture of water supplying bag in the Caijiachuan Watershed,Jixian County.Meanwhile we measured the soil physical and chemical properties,seedings survival rate and growth in different plantation that under different test treatments,and then analyzed those test data in the method of variance analysis,correlational analysis and regression analysis.The results were as follows:1.After the growing season(April to October,2015),soil moisture content of 0-60cm soil profile in the plantation was ranked in level terracesite preparation-LT(1 1.86%)>scale ripplesite preparation-SR(1 1.04%)>drill hole site preparation-DH(9.86%)>wild grass ground-CK(8.02%),soil bulk density was ranked in LT(1.32g/cm3)<SR(1.38g/cm3)<DH(1.40g/cm3)<CK(1.46g/cm3),soil organic matter content was ranked in LT(17.89g/kg)>SR(17.16g/kg)>DH(16.55g/kg)>CK(15.40g/kg),seedings survival rate was ranked in LT(86.7%)>SR(80.0%)>DH(73.3%),seedling height growth was ranked in LT(13.5cm)>SR(10.6cm)>DH(7.7cm).LT was the best measure in improving plantation microhabitat,and SR and DH were better than CK.The surface disturbance area and the cost of LT and SR were bigger than DH.DH was worth suggesting in planting for drought and steep slopeland in Loess Region of Western Shanxi.2.We measured the cumulative evaporation of area mulched with grass in soil(MGI),grass(MGO)and plastic film(MPO)on the surface from April 1 to 20,2015.They were 4.37,19.69 and 13.83mm,respectively,compared with which had non mulching treatment(CK),they decreased by 82.73%,22.28%and 45.38%.After the growing season,the soil moisture content in 0-60cm soil profile of MGI,MGO,MPO were 14.51%,13.01%and 13.18%,compared with CK,they increased by 3.47,1.97 and 2.14 percentage points respectively,seedings survival rate were 96.7%,90.0%and 93.3%,compared with CK,they increased by 33.4,26.7 and 30.0 percentage points,seedings height growth were 10.55,9.45 and 8.98cm,compared with CK,they increased by 54.69%,38.56%and 31.67%.MGI was the best measure in improving plantation microhabitat and it was worth suggesting in planting for drought and steep slopeland in Loess Region of Western Shanxi.3.After the growing season,the dosages of water retaining agent were 0,10,20 and 30 g/plant,and when the irrigation amount was 1L/plant,seedings survival rate were 66.7%,73.3%,66.7%and 60.0%,respectively.When the irrigation amount was 2L/plant,seedings survival rate were70.0%,76.7%,86.7%and 80.0%,respectively.When the irrigation amount was 3L/plant,seedings survival rate were 76.7%,80.0%,86.7%and 93.3%,respectively,seedings height and new branch growth increased with the increase of water retaining agent dosages.When the irrigation amount was 1 or 2L/plant and the dosages of water retaining agent was more than 20g/plant,seedings height and new branch growth didn't increased with the increase of water retaining agent dosages.Too much water retaining agent was bad for seedings survival and growth,but increasing the irrigation amount could reduce this adverse effect.The more dosages of water retaining agent needed more irrigation amount in planting for drought and steep slopeland in Loess Region of Western Shanxi.4.We carried out the test with big(BA),medium(MA)and small aperture(SA)water supplying bag from April 1 to May 20,2015.It was found that infiltrating and irrigating the plantation with MA,soil moisture content incresed from 15.02%to 18.90%,then stayed around 19.07%,with BA,soil moisture content incresed rapidly from 15.02%to 19.55%,then decresed to 7.17%,with SA,soil moisture content decresed from 15.02%to 6.15%.Watering 1 liter water to the plantation every five days(WA),soil moisture content stayed around 17.28%.The plantation had non treatment(CK),soil moisture content decresed from 15.02%to 5.06%.After the growing season,seedings survival rate of WA,MA,BA and SA were 86.7%,90.0%,73.3%and 63.3%,respectively,compared with CK,they increased by 26.7,30.0,13.3 and 3.3 percentage points,seedings height growth were10.8,10.6,7.5 and 6.9cm,respectively,compared with CK,they increased by 92.86%,89.29%,33.93%and 23.21%.WA and MA were more effective measures,however,MA could save 11.20 tons of water per hectare than WA.MA was worth suggesting in planting for drought and steep slopeland in Loess Region of Western Shanxi. |
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