退化草原群落地上生物量和多样性对改良措施的响应

Response of Aboveground Biomass and Diversity of Degraded Grassland Communities to Improvement Measures

为改良恢复已退化的草地,于2012年在退化草地上设置切根、围栏封育、浅耕翻等3种措施,与同期设置的由自由放牧引起的退化草地作为对照,并于2020年生长季高峰期对植物群落地上生物量、多样性等指标进行调查,结果表明:(1)与退化草地相比,实施改良措施9 a后,3种改良措施均可以显著提高植物群落地上生物量(P<0.05),且浅耕翻方式最好;3种改良措施均显著提高了群落中根茎型禾草的地上生物量(浅耕翻>切根>围栏封育>对照),而显著降低了丛生型禾草的地上生物量(对照>围栏封育>切根>浅耕翻)。(2)群落物种多样性在围栏封育下具有明显升高趋势,在浅耕翻和切根方式下均呈显著降低趋势,且群落物种多样性在切根方式下显著低于浅耕翻(P<0.05)。(3)群落中丛生型禾草地上生物量与群落物种多样性呈显著正相关关系(P<0.05),而根茎型禾草地上生物量与群落物种多样性呈极显著负相关关系(P<0.01)。综上所述,3种改良措施中,长期围栏封育对于多样性的维持具有一定促进作用,浅耕翻措施对群落生物量的恢复和提高具有较好效果。

In order to improve and restore degraded grasslands,three treatments were set up on degraded grasslands in 2012:fencing,shallow ploughing and root cutting,as compared to degraded grasslands caused by free grazing in the same period.The aboveground biomass and diversity of plant community were investigated in peak period of growing season in 2020.The results showed that:(1)Compared with degraded grassland,the aboveground biomass of the plant community in three improvement measures(P<0.05)were significantly increased after implementing the improvement measures for 9 years,and the effect was the best under the shallow ploughing method.The three improvement measures significantly increased the aboveground biomass of rhizome-type grasses(shallow ploughing>root cutting>fenced enclosure>control),and significantly reduced the aboveground biomass of cluster grasses(control>fenced enclosure>root cutting>shallow ploughing).(2)The community diversity showed a significant increasing trend under fenced enclosure,and showed a significant decrease under shallow ploughing and root cutting.The community diversity under the root cutting method was significantly lower than that of shallow ploughing(P<0.05).(3)There was a significant positive correlation between the aboveground biomass of clump grasses and the community diversity(P<0.05),while there was a very significant negative correlation between the aboveground biomass of rhizome grasses and the community diversity(P<0.01).To sum up,among the three improvement measures,long-term fenced enclosure had a certain promotion effect on the maintenance of diversity,and the shallow ploughing measure had a positive effect on the restoration and improvement of community biomass.