黄土高原植被不同演替阶段优势种的光合生理特性  

Photosynthetic characteristics of dominant plant species at different succession stages of vegetation on Loess Plateau

作　　者：安慧[1] 上官周平[1] 

机构地区：[1]西北农林科技大学黄土高原土壤侵蚀与旱地农业国家重点实验室,陕西杨凌712100

出　　处：《应用生态学报》2007年第6期1175-1180,共6页Chinese Journal of Applied Ecology

基　　金：中国科学院西部行动计划项目(KZCX2XB2053);西北农林科技大学拔尖人才与创新团队建设计划资助项目

摘　　要：在黄土高原子午岭林区,按照植被的演替序列,分别选择植被次生演替不同阶段的优势种—白羊草、铁杆蒿、沙棘、狼牙刺、山杨和辽东栎,对其土壤与叶片氮素含量、叶片气体交换参数、叶绿素含量及叶绿素荧光参数进行了观测.结果表明:随着植被演替,0～20cm土壤全氮含量呈增大趋势,植被优势种叶片氮含量先升高后降低,叶绿素含量变化与优势种叶片氮含量相似.灌木群落优势种(沙棘、狼牙刺)叶片氮含量明显高于其它群落优势种(P<0·05),草本群落优势种(白羊草、铁杆蒿)和灌木群落优势种的光合速率(Pn)高于早期森林群落优势种(山杨)和顶级群落优势种(辽东栎),叶片气孔导度(gs)与Pn变化规律相似.草本群落和灌木群落优势种叶片蒸腾速率(Tr)较高,随着演替的进行Tr逐步下降,顶级群落优势种辽东栎Tr较低.PSⅡ最大光化学量子效率(Fv/Fm)值呈缓慢增长趋势,辽东栎>山杨>沙棘>狼牙刺>铁杆蒿>白羊草,而PSⅡ量子效率(ФPSⅡ)值呈先增加后降低趋势;光化学淬灭系数(qP)在演替过程中呈整体增加趋势,而非光化学淬灭系数(qNP)呈先增加后降低趋势.这说明植被不同演替阶段优势种的光合生理特征以及对微生境的适应性存在明显差异.According to the succession sequence of vegetation on Ziwuling of Loess Plateau, the dominant species at different secondary succession stages, i. e. , Bothriochloa ischaemum, Artemisia gmelinii, Hippophae rhamnoides, Sophara viciifolia, Populus davidiana and Quercus liaotungensis, were selected to measure the total N contents in their leaves and soil, and the parameters of leaf gas exchange, chlorophyll content and chlorophyll fluorescence. The results showed that with the succession of vegetation, the total N content in 0-20 cm soil layer had an increasing trend, while the leaf total N and chlorophyll contents were increased first but decreased then. The leaf total N content of dominant species at shrub community stage （ H. rhamnoides and S. viciifolia） was significantly higher （P 〈 0. 05 ） than that at other succession stages, and the photosynthetic rate （Pn） was higher at the stages of herbaceous and shrub communities than at the early and climax stages of forest community. Stomatal conductance （ga） and Pn had the similar variation trends. The dominant species at the stages of herbaceous and shrub communities had a higher transpiration rate （ Tr） , while those at the climax stage of forest community had the lowest one. With vegetation succession, the maximum photochemical efficiency （Fv/Fm ） had a slow increase, while the actual photochemical efficiency of PS Ⅱ （ ΦPSⅡ ） was increased first but decreased then. Along the succession sequence, photochemical quenching coefficient （qp） presented an increasing trend, while non- photochemical quenching coefficient （qNp） showed a single-peaked curve. Therefore, the ecophysi- ological attributes and adaptation to microhabitats of early succession plant are different from the late succession plants.

关 键 词：光合特征 优势种 植被演替 黄土高原 

分 类 号：Q945[生物学—植物学]