• 论文与研究报告 •

### 黄土高原不同地区杜松种群结构与动态

1. 1. 西北农林科技大学林学院 杨凌 712100;
2. 宁夏贺兰山森林生态定位研究站 银川 750000;
3. 西藏职业技术学院 拉萨 850000
• 收稿日期:2013-12-31 修回日期:2014-04-30 出版日期:2015-02-25 发布日期:2015-03-11
• 通讯作者: 李登武
• 基金资助:

中央高校基本科研业务费专项资金项目(QN2011077)。

### Population Structure and Dynamics of Juniperus rigida in Different Regions of Loess Plateau

Zhang Yafang1, Li Dengwu1,2, Wang Mei1,3, Liu Pan1

1. 1. College of Forestry, Northwest A & F University Yangling 712100;
2. Ningxia Helan Mountain Forest Ecosystem Orientational Research Station Yinchuan 750000;
3. Tibet Vocational Technical College Lhasa 850000
• Received:2013-12-31 Revised:2014-04-30 Online:2015-02-25 Published:2015-03-11

【目的】 对黄土高原不同地区杜松种群结构与动态进行比较研究,阐明黄土高原地区杜松种群的生存现状与数量动态,揭示种群的发展趋势,为杜松种群恢复策略的制定提供依据。【方法】 采用样地调查法,选取黄土高原5个地区(内蒙古武川、山西浑源、陕西府谷、宁夏贺兰山和河北涿鹿)的杜松种群,根据杜松生活史特点并借鉴前人研究方法,划分种群径级、高度级和冠幅级,分别绘制其种群结构图。采用空间代替时间的方法,即用杜松的径级结构代替年龄结构,编制静态生命表,绘制存活曲线、死亡率曲线和消失率曲线。应用生存分析中的4个函数(生存函数、积累死亡率函数、死亡密度函数和危险率函数)分析杜松种群动态。【结果】 5个种群的径级结构均有不同程度的缺失; 涿鹿和浑源种群的高度结构相对完整; 5个种群的冠幅结构均有一定程度的缺失,武川、涿鹿和浑源3个种群冠幅面积大多集中在2 m2以内,贺兰山种群的冠幅面积大多在3 m2以上;种群静态生命表表明,杜松种群不同龄级的存活量差别较大,存活量随龄级的增加逐渐减少; 死亡率和消失率最高的均为Ⅳ龄级; 期望寿命最高的是Ⅰ龄级,武川种群的存活曲线趋于Deevey-Ⅲ型,其余种群则趋于Deevey-Ⅱ型;各种群死亡率和消失率曲线变化趋势基本一致,生存分析表明,武川种群前期略减、中期稳定、后期衰退,府谷种群前期锐减、中期稳定、后期衰退,涿鹿和浑源种群前期锐减、后期衰退,贺兰山种群则呈现前期略减、后期衰退的特征。【结论】 黄土高原不同地区杜松种群的径级、高度级和冠幅级结构均表现出一定的差异性。涿鹿和浑源种群密度相对较大且有一定幼龄植株储备,种群表现出一定的更新发展潜力; 府谷种群存在相当数量的中老龄株; 府谷、武川和贺兰山种群的径级结构相对完整,但种群密度较小且缺失幼龄植株。杜松从幼树成长为大树的过程中受到了相当程度的环境筛选和竞争压力,大树的生存能力增强。涿鹿和浑源种群有一定的幼苗储备,若改善生态环境保证幼苗的生存发展,种群是可以恢复与更新的; 府谷种群幼苗库的储备缺少,若不进行补充可能会限制种群的更新发展。在天然杜松种群的保护工作中,要注意保护萌蘖苗,防止动物啃食尤其人为放牧等的影响; 针对杜松种子自然条件下萌发率低的特性,应人为采取相关的技术措施,促其萌发; 对于府谷种群等老龄化严重的杜松种群,应该借助人工补充幼苗以保证种群的更新发展。

Abstract:

【Objective】Population structure and dynamics of plant can reflect the survival of the population and display the interaction between plant and environment. It is an important content of population ecology, and it has significant implications to protection and utilization of plant resources. Juniperus rigida is a wild tree species with priority for protection in Loess Plateau, a comparative study on structure and dynamics of Juniperus rigida populations in different regions of Loess Plateau was carried out to analyze population survival and dynamics of Juniperus rigida in Loess Plateau, in order to reveal the trend of population development. This study would have important theoretical and practical significance for developing strategies of rehabilitating Juniperus rigida population.【Method】A field survey was carried out on 5 populations of Juniperus rigida selected in 5 different regions in Loess Plateau (Wuchuan, Inner Mongolia; Zhuolu, Hebei; Hunyuan, Shanxi; Fugu, Shaanxi; Helanshan, Ningxia) by using sample plots. According to the characteristics of life history of the species and considering results from previous studies, diameter, height and crown width were divided into classes and population structure was constructed using the classes. Static life table, survival curve, mortality curve, disappearance rate curve were produced using space to replace time, i.e. diameter structure instead of age structure. 4 functions (survival, accumulative mortality, mortality density, and hazard rate) of survival analysis were used to analyze population dynamics of Juniperus rigida.【Result】 Different extents of absence of some diameter classes was found in diameter structure of 5 populations; Height structures of Zhuolu and Hunyuan populations were relatively complete; Certain extent of absence of crown-width classes were found in the 5 populations, the crown coverage of Wuchuan, Zhuolu and Hunyuan populations were mostly within 2 m2, while Helanshan population was mostly larger than 3 m2. The static life table showed that there were large differences of number of survival trees among different age classes, the number of survival trees decreases with age; the highest rate of mortality and disappearance rate were both in age class IV; and the highest life expectancy was in age class I. Two types of the survival curves of 5 populations were found, Wuchuan fitted Deevey-III while the others tended fit Deevey-II. The changes of mortality and disappearance rate were in similar trends for the 5 populations. Four survival curves of 5 populations showed that, the populations Wuchuan and Fugu reduced at young ages, grew stably at middle ages and declined at old ages, and Fugu showed a sharper reduction, while the populations Zhuolu and Hunyuan had a steep reduction in early growth and a late recession, and the population Helanshan reduced slightly at young ages and recessed late.【Conclusion】There were some differences among 5 populations of different regions in the structures of diameter class, height class and crown width class. Populations of Zhuolu and Hunyuan showed regeneration potential as the population density of them were relatively large and they also had a certain number of young plants; Fugu population had a considerable number of aging plant; the diameter class structures of Fugu, Wuchuan and Helanshan were relatively complete, while the population density were smaller and young plants were comparatively rare. There were environmental screenings and competitive pressures in the process of young trees growing up into big trees, and the survival ability of the big trees were stronger. The populations Zhuolu and Hunyuan could be restored and updated if the ecological environment could be improved as there were some young trees in Zhuolu and Hunyuan populations; the regeneration and development of Fugu population lacking young trees would be limited without the supplementation of young trees. In order to protect the populations of Juniperus rigida, attentions should be paid to protecting the young trees; and measures should be taken to promote germination as it was low under natural conditions; For populations with serious aging such as Fugu population, supplementary plantings should be used to ensure regeneration and development of the populations.