濒危植物疏花水柏枝种子萌发的生态学特性

Ecological characteristics of seed germination of an endangered species Myricaria laxiflora

疏花水柏枝Myricaria laxiflora分布于我国三峡从宜昌至重庆段长江干流的消落带,分布区十分狭小。三峡工程兴建后,疏花水柏枝将失去绝大部分的生境而成为濒危物种。通过设置一系列控制实验测试了土壤水质量分数,温度和土壤类型对疏花水柏枝种子萌发的生态学的影响。实验结果表明,土壤水质量分数、温度和土壤类型对种子萌发率都有显著影响。其中种子萌发率随土壤水质量分数增加而增大,土壤水质量分数达到饱和程度时萌发率达到最大值;高温条件下的种子萌发率高于低温,种子萌发率在21～27℃达到最大值;种子在河沙基质上萌发好于在沙土基质上。结合分布区萌发季节的环境条件分析,土壤水质量分数是限制该物种分布于消落带的关键作用因子。据此就该物种的种群保护与重建提出了一些建议。

Myricaria laxiflora is restricted within the water-level fluctuation zone along Yangtze River from Yichang to Chongqing and has a narrow distribution area. The species will lose most of habitats and become an endangered species when the Three Gorges project is finished and water level is raised. To understand its natural geographic distribution and provide information for population conservation, we designed a control experiment to study its ecological characteristics of seed germination. Results showed that the germination of Mercurial laxiflora seeds was significantly influenced by temperature, soil type and soil water moisture. The interactions among these ecological factors were also significant. Seeds germination increased with the increase of water content till soil became saturated. Mercurial laxiflora seeds preferred germinating at high temperature at the experimental range. The highest seed germination rate appeared when temperature ranged from 21 to 27 ℃. The seed germination rate on sand substrate was higher than that on sandy soil substrate. It could be concluded that soil moisture was the critical factor restricting Mercurial laxiflora to distribute on the riverbanks along Yangtze river when analyzing the research data with the local weather conditions during its germination season. Some suggestions were finally put forward for the population conservation based on the research results.