千岛湖消落带植物分布规律及适应水位变化机制研究

Research of Regularities of Plant Distribution and Mechanism to Adapt to Changes in Water Level of Hydro-fluctuation Belt in Qiandao Lake

由于水位的季节性变化,消落带上的植被会经历干湿交替,大部分不耐受生境急剧变化或无法适当调整生理结构、生活史特性的物种就会被淘汰。一旦物种多样性丧失,消落带就会出现生态系统功能下降如水土流失,或服务丧失如美观价值降低等。为消落带植被重建与恢复提供技术支撑,2014年11月至2015年10月在不同季节7次调查了千岛湖消落区4条样带,分析研究千岛湖消落带植物在消落带上的分布与组成规律,以及草本植物对水位季节性变化的适应机制。研究表明:聚类分析与PCA分析均反映出植物组成随海拔降低而变化。乔木、灌木和藤本植物物种丰富度的"单调递减",草本植物随海拔变化出现"先上升后下降"的规律,且峰值在最高水位附近。优势草本植物适应水位季节性变化的有5种不同机制:(1)生长期错开高峰水位,如鼠麴草、泥胡菜;(2)耐水淹,如狗牙根等深、密根性植物;(3)生长期或花果期提前,如大狼把草;(4)水陆两栖,如天胡荽、积雪草,但受水位变化速率快慢的限制较为明显;(5)在水淹没前及时补充土壤种子库,如一年蓬。

Due to the seasonal changes of water level, the vegetation in hydro-fluctuation belt will experience dry-wet alter- nant, most species intolerance foL rapid changes in habitat or unable to adjust physiology, life history characteristics will be eliminated. Once the loss of species diversity, ecosystem function decline, such as water and soil erosion, or loss of service such as decrease in aesthetic value will appear in hydro-fluctuation belt. To provide technical support for vegeta- tion reconstruction and recovery in hydro-fluctuation bclt~ surveyed four sample belts in hydro-fluctuation belt zone in Qi- andao Lake from November 2014 to October 2015 in different season for 7 times, analyzed and studied regularities of plant distribution and composition, and mechanism of herbaceous plant adapting to seasonal variation of water level of hydro-fluctuation belt in Qiandao Lake. Research showed that cluster analysis and PCA analysis reflect the plant compo- sition changes according to the altitudes reducing, i Species richness iof arbor, shrubs land vines plants monotone decrea- sing, herbaceous plants vary with altitude, turn up the rule of ＂rising first and decreasing later＂, moreover the peak near the highest water level. There are five different mechanisms for advantage herbaceous plants adapting to seasonal changes of water level： （1）growing period stagger peak levels, such as Gnat）halium a f fine, Hemisteta tratat（2） water-tolerant, dense root plants, such as Cynodon dactylon; （3） growing period or flowering fruit stage ahead of time, such as Bidens frondosa ; （4）amphibious, such as Hydrocotyle sibthorpioides, Centella asiatiea, but more obviously limited to the water level changing rate; （5）supplement Soil seed banks in time before submerging, such as Erigeron annuus.