岩溶石漠化治理优良先锋植物种类光合、蒸腾及水分利用效率的初步研究

Studies of photosynthesis,transpiration and water use efficiency of some dominant species in rocky desert area,Guangxi,China

针对西南岩溶石漠化地区干旱缺水的特点，采用Li-6400对其先锋树种任豆、金银花、狗骨木的光合、蒸腾及水分利用效率等特征进行分析，以揭示先锋树种利用水分生理生态学特征，从而提出植被恢复的对策。光响应模拟结果表明金银花和狗骨木符合Walker的非直线双曲线模型。蒸腾临界值狗骨木（幼树期）最小，金银花次之，任豆树较大，说明阳性树种任豆具有较大的蒸腾拉力，能够从土壤提取更多的水分，以减少岩溶石漠化地区强光引起的高温灼伤。任豆树、金银花、狗骨木具有同地带干性或沙漠优势植物的光合速率特征。任豆树有较耐受强光的能力，这与其在石漠化地区总是能够成为优势层片优势种的地位相符。三种植物光有效辐射与叶片蒸腾呈极显著的线性关系；任豆树的蒸腾作用受气孔调节明显；狗骨木有较高的水分利用效率。上午9点左右和下午5：00～6：00是这些石漠化地区植物水分利用最高时间段。可以说这三种植物具有适应石漠化地区干旱和高温的生理生态学适应特征和避旱避高温策略，并保持旺盛的生物生产力。从植物固定碳水化合物效率并提高水分利用效率而言，三种植物套种，任豆树能够对藤灌植物适当遮荫，对加速狗骨木生长，提高金银花的产量将具有较好的效益。

Water issue is considered as a key problem existing in karst＂rocky desert＂area, which is an impact to restoration of the ecosystem. This paper is to analyze the photosynthesis, transpiration and water use efficiency（WUE） of pioneer species, which thereby indicate the water physiological ecology of the species, thereafter to propose a measurement of the vegetation restoration. The result show that the parameter of light curve is given up to Walker＇ Nonlinear-Hyperbolic Model of all 3 species;critical transpiration of Cornus controversa is the lowest comparing to the other 2, while Zenia insignis is respectively the highest, consequently it is possible that Z. insignis process a higher evaporation potential, resulting in uptake more water from the soil in unit, thereby reduce the potential damage by sunburn. Z. insignis and Lonicera maackii and C. controversa are similar to the number of the subtropical dry forest and subtropical desert dominant species. C. controversa is much light-tolerance species that the other two,thereto signify the phenomena that it is growing better and is a pioneer dominant in Karst＂rocky desert＂area. The result also show a significant linear relationship between leaf transpiration and radiation of the 3 species. Z. insignis tends to be regulated by leaf stoma, but other two are not. The light saturated for WUE of eornus eontroversa is higher, which light level generally is the time around 9 ： 00 AM,or 5 ： 00-6 ： 00 PM,showing the high WUE period of a day. Therefore it can be concluded that these 3 species can process a physieeologieal drought and thermal adaptation and develop a strategy to escape environmental stress. Considering efficiency of photosynthesis and WUE, these three species intereropping would outcome that Z. insignis can properly shade the other two species therefore reduce the summer radiation damage to the young C. controversa and L. rnaackii that may advance the grow of the young and increase the yield of L. rnaackii as an economic species.