暖温带森林生态系统主要树种若干水分参数的季节变化

 本文通过PV技术对暖温带落叶阔叶林主要树种辽东栎(Quercus liaotungensis)、棘桦(Betula dahurica)、五角枫(Acer mono)、大叶白蜡(Fraxinus rhychophylla)及其林下灌木六道木(Abelia biflora)、山地针叶林的主要树种油松(Pinus tabulaeformis)以及次生灌丛主要树种山杏(Prunus armeniaca var.ansu)、山桃(Prunus davidiana)、大果榆(Ulmus macrocarpa)、北京丁香(Syringa pekinensis)的日最低叶水势Ψmin、饱和含水量时的最大渗透势Ψs sat、初始质壁分离时渗透势Ψs tlp、初始质壁分离的渗透水的相对含量(ROWCtlp)、相对含水量(RWCtlp)、质外体水的相对含量(AWC)6种水分生理指标的季节变化进行了研究。结果表明：1)所研究的10种树种叶水势Ψw min的季节进程基本与土壤湿度的变化一致。乔木Ψw min季节均值由低到高的顺序为油松<辽东栎<大叶白蜡<棘皮桦<五角枫。次生灌丛4种树种Ψw min季节均值由低到高依次为：山杏<山桃<北京丁香<大果榆。在生长季的不同时期，同为灌木、生长于落叶阔叶林下的六道木Ψw min均高于灌丛样地4类树种的同期值，且季节变幅较小。2)各树种饱和含水量时的最大渗透势Ψs sat和初始质壁分离时渗透势Ψs tlp，表现出随季节进程而不断降低的趋势；Ψs tlp和Ψs sat的季节变化并未表现出与土壤水分状况变化的一致关系，而与树木自身生长发育的物候节律有关。从Ψs tlp和Ψs sat指标所反映的树木耐旱能力的季节变化来看，表现为随季节进程不断上升的趋势。一般在展叶和随后的生长旺盛期，上述树种的耐旱能力较弱。3)初始质壁分离的渗透水的相对含量(ROWCtlp)和相对含水量 (RWCtlp)的季节变化在各树种间呈现大体相同的趋势，5月下旬的生长高峰期，达到生长季中的最高值。而后随林木当年生叶的成熟和嫩枝的木质化，ROWCtlp和RWCtlp呈下降趋势。4)各树种质外体水的相对含量(AWC)表现为随季节进程而上升的趋势。

The Hydro-physiological Characteristics of Major Plant Species of the Forest Ecosystem in the Warm Temperate Zone of Northern China

In this paper, a pressure-bomb technique was applied to measure the six physiological indices of ten main plant species in the forest ecosystem of warm temperate zone during the period from April to October of 1994. They were minimum water status of leaf (Ψmin), maximum osmotic potential at saturation point (Ψs sat), osmotic potential at incipient plasmolysis (Ψs tlp), relative water content at incipient plasmolysis (RWC), relative osmotic water content at incipient plasmolysis (ROWC), relative content of apoplectic water(AWC). The plant species under study were Quercus liaotungensis, Betula dahurica, Acer mono, Fraxinus rhychophylla, Abelia biflora, Pinus tabulaeformis, Prunus armeniaca var ansu, Prunus davidiana, Ulmus macrocarpa, Syringa pekinensis. The results were as follows: 1)The seasonal change of Ψmin showed the tendency similar to that of soil moisture in all the above tree species. 2)Ψs sat and Ψs tlp of the species continuously decreased in the course of the growth season, and were related to the phenological rhythm of the species. 3) The seasonal variations in ROWCtlp and RWCtlp, generally, tended to be similar for the different species in the whole growing season. In the end of May those two indices reached the maximum and then declined accompanying the maturity of leaves and twigs. 4)AWC of the species increased in growing season.