云南铁杉开花结实特性及其与环境因子的关系

Strobili and seed characteristics of Tsuga dumosa and its relationship with environmental factors

以进入生殖阶段的8个天然云南铁杉(Tsuga dumosa)种群为对象,对开花、结实植株(24个样株)的生长量进行测定,并采用标准枝法对不同树冠层次与方位的开花及结实数量进行调查,研究了开花结实规律和对其有主要影响的环境因子。结果表明:云南铁杉雌、雄球花比为1:2,雌球花转化为果实的数量仅占28%,胸径为7 cm(树龄约25年)的植株最早进入开花结实阶段,胸径为25–30 cm的植株开花结实量最高,胸径为89 cm(树龄约200年)的植株开花结实最晚;树冠不同层次与方位上开花结实数量有着明显的差异;相关性分析得出植株胸径与开花结实量极显著相关(p<0.01)、与冠幅显著相关,生境中林分郁闭度与开花结实量、株高、胸径之间均呈负相关关系,其中与结实量的相关性达显著水平;主成分分析得出植株开花及结实主要受到温度因子、水分因子、光照因子协同作用的影响。云南铁杉雌雄球花的比例偏雄性、结实周期长、结实方式不经济、灾害性天气的影响是造成该种群逐渐走向濒危的主要原因。因此,采用人工促进天然更新、建立母树林和种子园以提高种子的质量,对云南铁杉种群的恢复和保护具有重要意义。

Aims In this paper,we studied the timing and environmental factors associated with the production of male and female strobili（cones） of Tsuga dumosa using eight populations of reproductive age.Methods We measured the growth of 24 reproductive plants,and quantified the production of male and female cones at multiple canopy heights and directions using the standard branch method.Important findings The ratio of female to male cones was 1：2,and only 28% female cones developed seeds.Plants with a 7 cm diameter at breast height（DBH）（about 25 years old） begin producing cones first,while plants with DBH between 25 and 30 cm produced the highest abundance of male and female cones.A plant with a 89 cm DBH（about 200 years old） produced cones latest.There were obvious differences in the distribution of male and female cones at different canopy heights and orientations.Correlation analyses show that there was a significant positive correlation between DBH and cone（male and female） quantity（p 0.01）,and a significant positive correlation between DBH and the size of canopy.There was a negative correlation between canopy density and cone quantity,height,and DBH.The seed yield was significantly negative correlation.Analysis using principal components indicated temperature,water,and light exposure were the main factors affecting cone production.These factors caused population decline in the ratio between female and male cones towards male-biased,and seed bearing period is long and seed bearing way is not economic.Thus,weather conditions aggravated population decline.Artificial regeneration,establishing a seed orchard,and improving the quality of seeds are significant factors in the improvement of seed quality and population restoration.