毛乌素沙地油蒿和牛心朴子生理生态学研究

 作为毛乌素沙地植被主要建群种的油蒿(Artemisia ordosica)在一些地方出现了不同程度的退化，而萝摩科的一种多年生草本植物牛心朴子(Cynanchum komarovii)却出现了繁茂的生长。它们之间存在着一定的演替关系。本文通过对油蒿和牛心朴子的生理生态学特性和生殖生物学特性的研究及对其生境各要素的分析，说明了油蒿具有变水植物的特点，牛心朴子具有恒水植物的特点。在不同立地条件下，两种植物的光合、蒸腾及气孔行为都不相同。即便是在相同立地条件下，牛心朴子的水分利用效率亦显著高于油蒿；并且，牛心朴子只受轻微水分胁迫或不受水分胁迫，而油蒿则始终处于水分胁迫之下，说明牛心朴子在竞争中比油蒿占有相对的优势。在生态诸因子中，土壤水分状况是演替的外因，两种植物的水分生理生态特性和生殖生物学特征的差异是演替的内因。

PHYSILOGICAL ECOLOGY STUDIES ON ARTEMISIA ORDOSICA AND CYNANCHUM KOMAROVII IN THE MAOWUSU SANDLAND

The growth of Ariemisia ordosica, which is the main communityconstructing species, appears in some locations in the Maowusu sandland. Cynanchum komarocii, a perennial species; however, grows luxurantly throughout the area. There is obviously succession between these two species in experimental area. The characteristics of the two species are explained by our investigation based on physiological ecology, reproductive biology and by the analysis of fundamental elements of the environment.A. ordosica and C. komarovii are characteristic of anisohydric and isohydric plants respectively. The photosynthesis, transpiration and stomatal behavior of the two species are distinctly different from one location to another. The water-use efficiency of C. komarovii is much higher than that of A. ordosica. Furthermore, C. komarovii is more drought resistant and therefore less sensitive to water stress;A. ordosics, however, is less tolerant therefore more sensitive to wa- ter stress. The result is that C. komarovii is more dominant than A.ordosica in survival competetion. In conclusion, one of the main external factors of succession is the water content of the soil; the major internal factors of succession are the distinctive water physiological-ecological and reproductive biological characteristics of the two species.