摘要
为探讨巨柏Cupressus gigantea天然更新苗木生长的环境胁迫因子,以及造成巨柏天然更新困难、幼苗保存率低下的原因,研究选择朗县境内巨柏天然集中分布区3 种地类的巨柏更新样地进行实地调查,采用空间代替时间的方法,统计了巨柏幼苗、幼树、成树株数等种群天然更新指标特征,选取了地类、坡向、土壤质地、土壤紧实度、土壤温度、干扰强度等 19 个影响更新苗木生长的生境因子进行相关性分析.研究结果表明:巨柏幼苗到成树建成的过程中保存率仅为 1‰,符合数学模型:y=153.52x-3.528(R2=0.966 1);巨柏苗木生长过程受到环境因子的强烈筛选,与水线、阴坡、树冠遮荫≥50%、枯落物、石砾、沙壤、疏松、湿润、均温、轻微放牧干扰和较强放牧干扰因子呈正相关;与坡地、阶地、阳坡、树冠遮荫＜50%、砂砾、结皮、干燥、极端温度呈负相关;其中,苗木生长与阴坡和砂砾土呈显著相关,与疏松土壤呈极显著相关;越冬时生境因子温度的极端变化,是巨柏更新幼苗(1～5 a)生长过程中数量变化最剧烈的时期,15 a后苗木抗逆性明显增强,50%的幼树都可以顺利进入成树阶段.
Abstract
To explore the environmental stress factors for the growth of naturally regenerated Cupressus gigantea seedlings as well as the reasons for the difficulties in the natural regeneration of C.gigantea plants and its low percentage of seedling survival,the sample areas of C.gigantea regeneration of three land classifications in the areas where C.gigantea plants were naturally and concentratedly distributed in Lang county were selected in this study for field investigation,the method of space-for-time substitution was used to make statistics for the characteristic indexes of C.gigantea natural regeneration such as C.gigantea seedlings,saplings and survival rate,and meanwhile the correlation analysis was carried out on 19 habitat factors including land classification,aspect,soil texture,soil density,soil temperature and interference strength that affect the growth of regenerated C.gigantea seedlings.The results showed that the percentage of seedling survival from seedling to mature tree was only 1‰,which was consistent with the mathematical model:y=153.52x-3.528(R2=0.966 1);the growth process of C.gigantea seedlings was strongly affected by environmental factors,showing a positive correlation with the factors such as waterline,shady slope,canopy shading≥50%,litter,gravel,sandy soil,loose,moist,uniform temperature,slight disturbance and strong disturbance factors;and it was negatively correlated with sloping land,terrace,sunny slope,canopy shading＜50%,gravel,crust,dryness and extreme tempera-ture,and among them,the growth of seedlings was significantly correlated with shady slope,gravel soil and free soil;the extreme change of habitat factor temperature during overwintering was the most drastic period dur-ing the growth of regenerated C.gigantea seedlings(1-5 a).The seedling resistance was significantly enhanced after 15 years,and 50%of the young trees could successfully grow into mature trees.
基金项目
雅江清能生态环保(成都)有限公司科技项目(CD2C202201)
西藏高原林业生态工程重点实验室资助()
NETL
NSTL
万方数据