Study on reproductive characteristics of Pinus tabulaeformis f. shekannesis populations in Ziwuling region of the Loess Plateau | 黄土高原子午岭柴松种群生殖特性研究

Chinese. 探索柴松(Pinus tabulaeformis f. shekannesis)种群的基本生殖特性，为柴松种群的持续发展和合理经营管理提供依据。在对黄土高原子午岭地区柴松分布范围进行全面踏查的基础上，选择不同生境(阴坡、半阴坡和半阳坡)柴松生长发育较好的地段设置12块样地，分析不同生境下柴松种群的生殖年龄(Ar)、球果在树冠上的分布格局、结实和产种数量、生殖力表以及环境因子。（1）柴松种群的最小生殖年龄（Armin）、最大生殖年龄(Armax)、平均生殖年龄（ ）和周限生殖年龄(Apc)值分别为18，130，48和112年，不同生境条件下柴松种群的生殖年龄差异较大，其中Armin和 值为阴坡＞半阴坡＞半阳坡，Armax和Apc值为半阳坡＞半阴坡＞阴坡。（2）不同生境中的柴松种群均具有结实能力，阴坡种群的单株球果数和种子数均较高，各种群球果主要分布在树冠上部及东、北方向。（3）生殖力表显示，随着年龄的变化，生殖力存在低→高→低的趋势，阴坡和半阴坡柴松种群的生殖旺盛期为50~90年，半阳坡为30~50年；并且阴坡柴松种群具有较强的生殖能力，是柴松种群的最适生存环境。（4）主成分分析表明，人为干扰（0.984）和土壤水分含量（－0.974）是影响柴松种群生殖的最主要因子。柴松林经营管理要以就地保护为主，并应根据种群所在区域的生境条件进行分类管理。

English. The study was done in order to characterize reproduction ecology of Pinus tabulaeformis f. shekannesis populations and to produce some theoretical basis for reasonable exploitation and utilization. Reproductive age, fecundity table and the environmental factors of P. tabulaeformis f. shekannesis populations in different natural habitats, and 12 plots (shade slope, semi-shade slope and semi-sunny slope) located in the better sections of growth and development were investigated through comprehensive investigation in concentrated distribution area of P. tabulaeformis f. shekannesis populations in Ziwuling region of the Loess Plateau. (1) The values of Armin, Armax, and Apc of P. tabulaeformis f. shekannesis populations were 18, 130, 48 and 112 years respectively; The values of Armin and were cloudy slope＞semi-cloudy slope＞semi-sunny slope, and the values of Armax and Apc were Semi-sunny slope＞semi-cloudy slope＞cloudy slope; (2) The results showed that 3 populations had potential to produce seeds, and the higher yield occurred in the population located in the shade slope; The most cones appeared on the upper foliage of the tree, and the south and east aspects of the crown; (3) The fecundity table showed that reproductive ability and value took on low high low tendency with age increasing, and the booming of cloudy slope and semi-cloudy slope were 50C90 years and the booming of semi-sunny slope was 30C50 years; Furthermore, P. tabulaeformis f. shekannesis population in cloudy slope had the longest life span and the greatest fitness; (4) According to the principal components analysis (PCA) of the main environmental factors, the human disturbance (0.984) and water content of soil (－0.974) were the most important factors. Site conservation and classification management based on different habitats should be carried out in the future for the P. tabulaeformis f. shekannesi.