The Study On Physiological And Ecological Adaption Of Typical Plant In Karst Rocky Desertification Of Heqing, Yunnan

Karst rocky desertification (KRD) is widely spread in Heqing County in northwest of Yunnan province. Quercus monimotricha, Photinia prionophylla, Viburnum atrocyaneum, and Lithocarpus variolosa are the representative plants in the County. The four plants were chosen as the experimental materials and amount of physiological and ecological data were obtained by field monitoring and indoor experiment. Correlation analysis and variance analysis were used to analyze the different indexes of the4plants at different KRD levels. The indexes were mainly divided into two parts. One was the photosynthesis and physiological Adaptability indexes, such as photosynthetic rate(Pn), transpiration rate(Tr), and stomatal conductance (cond) etc. The other was the physiological and biochemical adaptation indexes, including nutrient contents, chlorophyll content, soluble polysaccharide content, soluble protein content, MDA content, proline content, CAT, POD activity. The membership degrees of drought indicators were calculated at different KRD levels using subordinate function method and the drought resistance were evaluated by index method. The results showed that:1) At different KRD levels, the same plant has different adaptation mechanisms:non rocky desertification> slight rocky desertification> moderate rocky desertification>sever rocky desertification;2)At the same KRD level the4plants differ greatly in the adaptation characteristics:Quercus monimotricha> Photinia prionophylla> Viburnum atrocyaneum>Lithocarpus variolosa. The major conclusions of this paper are as follows:1、The diurnal variation curves of net photosynthetic rate of the four plants can be roughly divided into two categories:For the Quercus monimotricha and Lithocarpus variolosa, there are presented "two peaks" at the non-KRD and slight KRD level,"single peak" in the moderate KRD level, and irregular peaks in sever KRD level. The diurnal variation curves of transpiration rate and stomatal conductance as "single peak" at all the4KRD levels.2) For the Photinia prionophylla and Viburnum atrocyaneum, the diurnal variation curves of net photosynthetic rate are mainly "single peak" at all KRD levels, except a presented "double peaks" in the obvious rocky desertification level of Photinia prionophylla, the diurnal variation curves of transpiration rate and stomatal conductance as "double peaks" at slight and moderate KRD levels, and "single peak" at sever KRD level. 2、For the4plants, the change trends of Photosynthesis-light response curve are the same. According to the photosynthesis capability, Quercus monimotricha> Photinia prionophylla> Viburnum atrocyaneum>Lithocarpus variolosa, and to the light energyconversion efficiency, Viburnum atrocyaneum> Photinia prionophylla> Lithocarpus variolosa> Quercus monimotricha.3、The correlation analysis among net photosynthetic rate and the factors of the corresponding physiological and ecological show that there are some differences and partial similarity in the influence factors. The main factors affecting the net photosynthetic rate are stomatal conductance (Cond), transpiration rate (Tr), air CO2(Ca) and air relative humidity (RH).4、Quercus monimotricha has the highest leaf nitrogen contents during the4plants, which is consistent with its strong ability of photosynthesis. The analytical data show that the content of full calcium and full magnesium in leafs from high to low as Viburnum atrocyaneum> Photinia prionophylla> Quercus monimotricha> Lithocarpus variolosa. As the KRD levels from slight to sever level, some indexes are uptrend, such as leaf Soluble polysaccharide content, MDA content, Soluble protein content, and the CAT activity etc; however, the content of Chlorophyll a and Chlorophyll b, total Chlorophyll and Proline content are downtrend, and the activity of POD is down first and then up.5、The leaf water content, leaf dry weight, leaf thickness, leaf area and specific leaf area of the4plants are downtrend with the KRD levels increasing. Compared with Quercus monimotricha and Photinia prionophylla, the Lithocarpus variolosa is advanced in water content, dry weight, specific leaf area and leaf thickness. The results accord with the characteristics of photosynthetic, physiological and biochemical for the4plants.6、It is found that as the KRD levels increasing, the tendency of average Membership degree of the4plants are uptrend. In the same KRD level, the average Membership degree have a large difference among the4plants. The orders are as follows:Quercus monimotricha>Photinia prionophylla> Viburnum atrocyaneum>Lithocarpus variolosa. This study concluded that the Quercus monimotricha is the highest resistance specie and has the strongest acclimation to the KRD environment in HeQing; Photinia prionophylla and Viburnum atrocyaneum are mild resistance species and stronger acclimation; and Lithocarpus variolosa,is low resistance specie, with weak adaptability.