沙地植物幼苗生长对降水和风速变化的响应

Response of Plant Seedling Growth to the Changes in Precipitation and Wind Velocity in Horqin Sandy Land

为研究沙地植物幼苗生长对降水和风速变化的响应过程,于2016年4月中旬利用40个2m×2m×2m的混凝土样方池,通过人工增雨及遮风网降低风速的方法开展模拟控制实验。结果表明:①风速、降水以及两者的协同作用对萌发物种数无显著影响(P> 0. 05)。风速降低20%和降水增加60%使种子萌发物种数与对照相比分别增加4.9%和1.3%;风速降低20%条件下,自然降水和降水增加60%均可使种子萌发物种数增加7. 2%。②不同降水处理会使植物幼苗密度大幅度降低、高度波动变化;风速降低可以较显著地促进沙地植物幼苗生长高度,特别是优势植物猪毛菜(Salsola collina)、大果虫实(Corispermum macrocarpum)的生长高度(P <0.01)。在自然风速条件下,降水增加30%明显促进猪毛菜幼苗高度生长,降水增加60%则相反;风速降低20%条件下,降水增加60%可以大幅度的促进雾冰黎(Bassia dasyphylla)幼苗的生长高度;风速降低40%与降水增加30%和60%的协同作用使雾冰黎、猪毛菜和大果虫实幼苗的生长高度均明显降低。③不同风速和降水处理对植被的Simpson优势度指数(D)、香浓–威纳多样性指数(H)、Pielou均匀度指数(J)无显著影响(P>0.05)。以上研究结果表明:降水增加30%对种子萌发阶段物种丰富度的抑制作用较大;与降水相比,风速是沙地植物幼苗生长高度的主要影响因素,并且自然降水条件下,风速降低40%可以使沙地植物幼苗生长高度最大限度地增加;沙地植被物种多样性指数对降水及风速的变化不敏感,这说明科尔沁沙地生态系统群落结构相对较为稳定。

To study the response of plant seedling growth to the change of precipitation and wind velocity in sandy land,we carried out simulation control experiments by artificial precipitation and wind screen reduction in 40 concrete square pools of 2 m × 2 m × 2 m during the period of seed germination starting in mid-April 2016. The results showed that:① Wind velocity,precipitation and interaction of these two treatments had no significant effect on the species richness (P > 0. 05). The seed germination rates could be increased by 4. 9% and 1. 3% under the 20%wind velocity reduction and 60% precipitation increment,respectively,compared with those of controlled experiment. The species richness was increased by 7. 2% under 20% reduction of wind velocity and 60% precipitation increment.② The seedling density and height fluctuated greatly under different precipitation treatments. A wind speed reduction can significantly promote seedling growth height in sandy land,especially for Salsola collina and Corispermum macrocarpum (P < 0. 01). Under the condition of natural wind speed,30% precipitation increment obviously promoted the growth of seedling height,while 60% precipitation increment was contrary. Under the 20%wind velocity reduction,the growth height of Bassia dasyphylla seedlings could be greatly promoted by the 60% precipitation increment. The synergistic effects of the 40% wind velocity reduction and 30% and 60% precipitation increments resulted in a significant decrease in the growth height of the seedlings of Bassia dasyphylla,Salsola collina and Corispermum macrocarpum.③ The effects of different wind velocity and precipitation treatments on species diversity,including the Simpson index (D),Shannon-Winner index (H) and Pielou evenness index (J),were not significant (P > 0. 05). In conclusion,the effect of 30% precipitation increment on the species richness during the period of seed germination was significant,wind velocity was the main factor affecting the height of plant seedlings.Under the natural conditions,the increase of seedling height was the maximum under 40% wind velocity reduction.The response of species diversity to the change of wind velocity and precipitation was not sensitive,which indicated that the community structure of the ecosystem was comparatively stable in the Horqin Sandy Land.