CAJ | 학술논문

通过对海拔4 320 m以上林线0.8 hm2样地方枝柏(Sabina saltuaria)种群的每木调查,分析了阳坡林线特征、种群结构、数量动态及时间序列预测.结果表明,西藏色季拉山海拔4 320 m为森林郁闭上限,阳坡林线上限为4 520 m,属渐变型林线;方枝柏种群径级结构中Ⅰ～Ⅳ龄级个体所占比重较大,此后种群数量随径级增大而急剧减少;种群存活曲线介于DeeveyⅠ和DeeveyⅡ之间,基本趋于稳定.死亡率(q_x)和消失率(k_x)变化基本趋势一致,都在Ⅲ龄级出现低谷,以后死亡率和消失率曲线均随龄级增加而上升;时间序列分析表明,未来种群发展老龄个体逐渐增多.说明方枝柏种群在Ⅳ龄级前能够适应高山林线区域特殊的生境条件,生长较好并发育到青壮年期,此后由于竞争加剧,导致种群发生自疏.这也是种群自身生物学特性和环境条件等因素共同作用的结果,也是高山生态系统恶劣生境中种群的一种适应对策.
통과대해발4 320 m이상림선0.8 hm2양지방지백(Sabina saltuaria)충군적매목조사,분석료양파림선특정、충군결구、수량동태급시간서렬예측.결과표명,서장색계랍산해발4 320 m위삼림욱폐상한,양파림선상한위4 520 m,속점변형림선;방지백충군경급결구중Ⅰ～Ⅳ령급개체소점비중교대,차후충군수량수경급증대이급극감소;충군존활곡선개우DeeveyⅠ화DeeveyⅡ지간,기본추우은정.사망솔(q_x)화소실솔(k_x)변화기본추세일치,도재Ⅲ령급출현저곡,이후사망솔화소실솔곡선균수령급증가이상승;시간서렬분석표명,미래충군발전노령개체축점증다.설명방지백충군재Ⅳ령급전능구괄응고산림선구역특수적생경조건,생장교호병발육도청장년기,차후유우경쟁가극,도치충군발생자소.저야시충군자신생물학특성화배경조건등인소공동작용적결과,야시고산생태계통악렬생경중충군적일충괄응대책.
Sabina saltuaria is an endemic timberline tree in the Qinghai-Tibetan Plateau, China. It is mainly distributed in the elevations between 4 320 m and 4 520 m on the sunny slope of the Sejila Mountain.One 0.8 hm~2 sample plot was established at the timberline >4 320 m on the sunny slope of the Mountain.Parameters, such as tree height,DBH,or diameter at base for seedlings and saplings, and location of each individual were recorded.The timberline features, population structure,dynamic and the time sequence prediction were investigated.The results showed that:(1)the upper elevation limit of the closed forests was found to be 4 320 m;the timberline elevations was 4 520 m on the sunny side with a gradualtype;(2) for the diameter class structure of the populations, most individuals were from Ⅰto Ⅳ, the number decreased sharply with the increase of diameter class, the survival curves were between Deevey type Ⅰ and Ⅱ, with an approximately stalbe trend;the variation trends of mortality rate (q_x) and hazard rate (k_x) were similar;(3)the analysis by time sequence model demonstrated that the individuals of the older age class would be increasing, indicating that S. saltuaria grew well before reaching the age class Ⅳ, and could adapt the timberline habitat conditions;but after Ⅳ,population self-thinning appeared because of the fiercer competition.It resulted from the biological characteristic of S. saltuaria, environment,as well as an adaptation strategy in ecological restoration of the high-altitude ecosystem.