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通过对青海海北高寒矮嵩草(Kobresia humilis)草甸进行为期3年的野外控制试验,研究了刈割(留茬1cm、3cm及不刈割)、施肥(2.5g·m-2尿素+0.6g·m-2磷酸二胺、不施肥)和浇水(20.1kg·m-2、不浇水)处理对矮嵩草补偿生长(包括分株密度、株高和分株地上生物量)的影响,及其比叶面积、叶片净光合速率和相对增长率的变化,探讨矮嵩草补偿生长的机制。研究结果表明:刈割后,矮嵩草的补偿生长高度和比叶面积显著降低;分株密度有增加的趋势,但会随刈割强度的增加而下降;株高和生物量的相对增长率随刈割强度的增加而呈上升趋势;补偿地上生物量在重度刈割处理下最高。施肥能显著增加矮嵩草的补偿高度、分株密度、补偿地上生物量、株高相对增长率、生物量相对增长率、比叶面积和净光合速率;与不浇水处理相比,浇水处理对重度刈割处理下的分株地上生物量、密度相对增长率、比叶面积和净光合速率无影响,而显著降低了中度刈割处理下的补偿高度和株高相对增长率,提高了不刈割处理下的分株密度和重度刈割处理下的生物量相对增长率。刈割、施肥和浇水处理的交互作用也显示出刈割与施肥对矮嵩草补偿生长具有拮抗效应,而刈割与浇水具有协同效应。上述结果说明,矮嵩草在刈割后可通过增加分株密度和相对增长率等途径来提高补偿能力,弥补在生长高度上出现的低补偿,而施肥可显著抵消刈割的不利影响,提高矮嵩草的补偿能力。
A three-year field experiment was conducted on the Kobresia humilis meadow in Haibei, Qinghai Province. The effects of mowing (stubble 1cm, 3cm and no cutting), fertilization (2.5g · m-2 urea +0.6 (including ramet density, plant height, and aboveground biomass) of Kobresia humilis under the condition of watering (20.1 kg · m-2, without watering) The specific leaf area, the net photosynthetic rate and the relative growth rate of Kobresia humilis. The results showed that after the cutting, Kobresia compensatory growth height and specific leaf area decreased significantly; ramet density tended to increase, but decreased with increasing cutting strength; relative growth rate of plant height and biomass With the increase of cutting intensity, it showed an upward trend; the compensation of aboveground biomass was the highest under the condition of heavy cutting. Fertilization can significantly increase Kobresia compensation height, ramet density, compensated aboveground biomass, relative growth rate of plants, relative growth rate of biomass, specific leaf area and net photosynthetic rate; compared with no watering treatment, watering The treatment had no effect on aboveground biomass, relative growth rate, specific leaf area and net photosynthetic rate of ramet under severe mowing treatments, but significantly reduced the compensatory height and plant relative growth rate under moderate mowing treatments and increased The ramet density under no mowing and the relative growth rate of biomass under heavy mowing treatment. The interaction of cutting, fertilizing and watering treatments also showed that cutting and fertilization had antagonistic effect on the compensatory growth of Kobresia humilis while cutting and watering had a synergistic effect. The above results showed that Kobresia increased the compensatory ability by increasing the ramet density and relative growth rate after mowing to make up for the low compensation appeared in the growth height, while the fertilization could significantly offset the adverse effects of mowing and increase Kobresia compensatory ability.