摘要
以额济纳胡杨为研究对象,对种子雨的散布时间、强度、散布距离以及种子雨和空气湿度、风之间的关系进行了研究。胡杨种子雨可以分为初始期、高峰期和消退期3个阶段,大部分的种子集中在高峰期落下。种子的散布主要受湿度和风的影响。湿度对种子雨的强度起主要作用,在一天之中,种子在湿度较低的中午和下午集中散落。应用一元线性回归模型对种子雨强度和相对湿度进行分析后表明二者之间存在显著的负相关关系。对种子的散播距离进行研究后发现,大部分种子落在母树附近,少部分种子能够进行长距离传播。风对种子的传播的方向和距离起决定性的作用,不同方向上的种子传播距离和强度相差很大。在顺风方向上,种子的传播距离最远,所有的长距离传播现象几乎都发生在这一方向上;而在主风向的垂直方向和逆风方向上,种子的散布距离较小,很少有种子能够进行长距离传播。对风的观测表明中午后和下午初的风力较强,而此时种子雨强度又最大,有利风力条件和高种子雨强度出现的同步性可能是促进胡杨种子进行长距离传播最有效的生物控制机制。由于胡杨种子在自然条件下的存活时间非常短暂,所以研究中不同胡杨母树林间种子散播时间的差异可能是胡杨种群内部为适应不同洪水期所表现出的风险分摊机制所造成的。
The proposed investigation is carried on seed rain time, seed rain intensity, seed dispersal distance, the effects of humidity and wind in fastigium phase. The seed rain duration of a plot fell into three successive phases-starting phase, fastigium phase and subsidizing phase, Humidity and wind had great effects on the seed dispersal. The seed rain intensity was positively correlated to humidity, most seed dispersed in the noon and afternoon when the humidity was relatively low in daylight. The longevity of the seeds under full light and shade conditions were 6d and 40d,respectively. We found that wind affected direction and distance of seed dispersal： the majority of the seeds distributed close to the maternal trees, only a little part of seeds had long-distance dispersal. Wind factor determined direction and distance of the seed dispersal. In the direction of wind, seeds had dispersal with longest distance, almost all the long-distance dispersal took place in this direction~ in the vertical and upwind direction, the seeds were more likely to distribute close to the maternal tress. The wind speed was highest between noon and early afternoon, and the seed rain intensity got the climax simultaneously. The synchronization of wind speed and seed rain intensity was an effective plant-controlled mechanism that facilitates Populus euphratica＇s seed longdistance dispersal. Duo to the brevity of seed longevity under natural conditions, the difference of seed rain time among the three plots in our study might result from Populus euphratica＇s adaptation to the temporal changes of the flood.
出处
《生态学报》
CAS
CSCD
北大核心
2005年第8期1994-2000,共7页
Acta Ecologica Sinica
基金
国家自然科学基金资助项目(30471369)~~
关键词
胡杨
种子扩散
时空分布格局
生物控制机制
Populus euphratica
seed dispersal
spatiotemporal pattern
plant-controlled mechanism
