摘要
枝、叶是植物的两个重要功能器官,密度制约下其异速生长关系不仅是植物个体发育过程的表现,也是植物与环境互相作用的结果。柽柳是干旱区湿地的主要植物之一,密度制约下其小枝与叶的异速生长关系对于理解干旱区湿地环境下植物的资源利用策略具有重要意义。在兰州市秦王川干旱区湿地,将柽柳(Tamarix gansuensis H.Z.Zhang)种群分为Ⅰ(0.1—0.35棵/m^2)、Ⅱ(0.35—0.6棵/m^2)和Ⅲ(0.6—0.85棵/m^2)3个密度梯度,应用标准化主轴估计(standardized major axis estimation,SMA)法,研究了不同密度下,柽柳当年生小枝长度与叶面积、叶数量的生长关系及叶片光合特性。结果表明:随着柽柳种群密度的增加,群落土壤含水量逐渐增加,土壤容重、pH值和电导率逐渐减小;柽柳平均高度、郁闭度、枝长度和叶面积呈逐渐增大趋势,冠幅、基径、分枝角度、叶数量和光合有效辐射呈逐渐减小趋势;叶面积指数、净光合速率、蒸腾速率和气孔导度先增加后减小。枝长度与叶面积、叶数量在不同的密度梯度下显著正相关(异速斜率k>0,P<0.05),随着密度梯度的增加,枝长度与叶面积的回归斜率逐渐减小(异速斜率0.65≤k≤0.98,P<0.05),枝长度和叶数量回归斜率不变(异速斜率k=0.9,P<0.01),截距沿着y轴显著的正向移动(截距0.25—1.93)。随着种群密度的增加,柽柳由较小枝长度、叶面积和较大分枝角度、叶数量的枝叶构建模式,发展为较大枝长度、叶面积和较小分枝角度和叶数量的垂直空间拓展模式并提高气孔导度、光合速率和蒸腾速率、降低水分利用效率,反映了该物种在干旱区湿地环境中、密度制约条件下的表型可塑适应机制和资源利用策略。
Twig and leaf are the two most important functional organs of the plant. Under a particular density, their allometric relationship is the result not only of individual development but also of the interplay between the plant and the surroundings. Tamarix gansuensis is one of the key species in harsh environments of arid regions, and the allometric relationship of its twig and leaf plays an important role in resource utilization strategies of wetland plants. In this study, the community of T. gansuensis was divided into three density gradients in Qinwangchuan wetland-low density （0.1-0.35 trees/m2）, medium density （0.35-0.6 trees/m2）, and high density （0.6-0.85 trees/m2）. The relationship between twig and leaf growth and the photosynthetic characteristics of the leaves were studied. Results showed that, with increase in density, soil moisture, plant height, canopy closure, twig length, and leaf area increased, while soil bulk density, pH value, electric conductivity, crown width, branch diameter, bifurcation angle, leaf number, and photosynthetically active radiation decreased. Leaf area index, net photosynthetic rate, transpiration rate, and stomatal conductance increased firstly then decreased. There was a significantly positive correlation （regression slope k 〉 0, P 〈 0.05） between twig length and leaf area. With increase in density, the regression slope between the twig length and the leaf number was the same （regression slope k=0.9, P 〈 0.01）, but its intercept was subject to a positive shift along the y axis （Y-intercept was from 0.25 to 1.93）. The regression slope between the twig length and the leaf area decreased （regression slope 0.65 ≤ k ≤ 0.98, P 〈 0.05）. These results showed that there was an allometric relationship between the twig and the leaf. With increase in density, the twig-leaf constructive mode of shorter twig length, lower leaf area, larger bifurcation angle, and larger leaf number under low density evolved into the expansion mode of longer twig length, larger leaf area, and smaller bifurcation angle and leaf number under high density. The stomatal conductance, net photosynthetic rate, and transpiration rate increased, while water use efficiency decreased. All these findings reflected the phenotypic plastic adaptation and the resource utilization strategy of the T. gansuensis in arid areas.
作者
赵连春
赵成章
陈静
王继伟
李群
ZHAO Lianchun,ZHAO Chengzhang, CHEN Jing, WANG Jiwei, LI Qun(College of Geography and Environmental Science, Northwest Normal University, Research Center of Wetland Resources Protection and Industrial Development Engineering of Gansu Province, Lanzhou 730070, Chin)
出处
《生态学报》
CAS
CSCD
北大核心
2018年第5期1722-1730,共9页
Acta Ecologica Sinica
基金
国家自然科学基金(41461013
91125014)
关键词
功能性状
光合特性
秦王川湿地
不同密度
资源利用
functional traits
photosynthetic characteristics
Qinwangchuan wetland
different density
resource utilization
