短期刈割对晋北农牧交错带草地生物量的影响

The effect of short⁃term mowing on grassland biomass in agro⁃pastoral ecotone of northern Shanxi Province

刈割是草地的主要管理方式之一,适度刈割不仅可以提高草地生物量,而且能够维持草地稳定性和物种多样性。农牧交错带草地受到人类生产生活的多重干扰,如何合理利用农牧交错带草地是协调生产和生态平衡的瓶颈问题。为研究刈割对农牧交错带草地生物量的影响,于2016年在山西右玉典型农牧交错带草地设置了不同刈割强度试验平台。通过留茬高度10 cm(LM,Light mowing),5 cm(MM,Moderate mowing)和2 cm(HM,Heavy mowing)来表征刈割强度,并设置不刈割处理(CK,No mowing)作为对照。研究不同刈割强度对优势物种赖草(Leymus secalinus)叶片、茎秆的生物量,群落地上生物量和不同土层(0—10 cm、10—20 cm和20—30 cm)地下生物量的影响。结果表明:连续3年刈割导致群落地上生物量逐年显著降低(P<0.05),但在干旱年份促进了土壤表层(0—10 cm)根系生物量的积累。与不刈割相比,短期轻度刈割和中度刈割显著降低群落地上生物量(P<0.05),重度刈割对群落地上生物量影响不显著(P>0.05),但对优势种赖草地上生物量有促进作用。刈割主要增加0—20 cm土层的地下生物量,但不同刈割强度对群落地下生物量无显著影响(P>0.05)。可为农牧交错带畜牧业生产、草地合理利用和生态保护提供科学依据。

Mowing is one of the main management methods for grasslands.Moderate mowing not only increase grassland productivity,but also maintain high species diversity and stability of the grassland ecosystem.The grassland in agro-pastoral ecotone is subject to multiple interferences from human production and life.How to coordinate grassland production and ecological balance in agro-pastoral ecotone is an urgent problem that needs to be solved.In order to study the effect of mowing on grassland productivity in agro-pastoral ecotone,an experimental platform with different mowing intensity was set up in the typical agro-pastoral ecotone of Youyu County,Shanxi.Mowing intensities were represented by stubble height of 10 cm(LM,Light mowing),5 cm(MM,Moderate mowing)and 2 cm(HM,Heavy mowing),and enclosed plots were set as the control(CK,No mowing).We used the“harvest method”to collect and monitor the leaves and shoots biomass of dominant species(Leymus secalinus),aboveground biomass,and belowground biomass at different soil depths(0—10 cm,10—20 cm and 20—30 cm)of plant communities under different mowing intensities.The results showed that:Three years of continuous mowing reduced aboveground biomass of the plant community year by year(P<0.05),while also decreasing belowground biomass year by year,but it promoted the accumulation of root biomass on surface of soil(0—10 cm)in drought years.Compared with no mowing,short-term light mowing and moderate mowing significantly reduced aboveground productivity of the community(P<0.05),while heavy mowing had a promotion effect on the biomass of L.secalinus,which is an absolute dominant species in the community.Mowing could promote root growth in 0—20 cm soil layer,but different mowing intensities had no significant effect on belowground productivity of community(P>0.05).Mowing increased the root to shoot ratio of plant communities,which first increased and then decreased with increasing mowing intensity,and reached its maximum value during moderate mowing.In drought years,no or light mowing management should be adopted to alleviate the environmental pressure on grassland.In wet years,heavy mowing management should be adopted to obtain higher aboveground biomass.Thereby achieving coordinated development between grassland production and ecology.Our work has found that short-term mowing management can affect the biomass of dominant species,above-and belowground biomass of grassland plant communities in agro-pastoral ecotone of northern Shanxi.This can provide the scientific basis for livestock production,rational utilization and ecological protection of grassland in agro-pastoral ecotone.