Under the treatment of different concentrations of polyethylene glycol(PEG 6000),the carbonic anhydrase activity,photosynthetic responses to light and CO_2,and chlorophyll fluorescence characteristics in leaves of two woody plant species,paper mulberry(Broussonetia papyrifera)and mulberry(Morus alba),were determined.The drought resistance of the two species plants was compared.The results indicated that the activity of carbonic anhydrase in paper mulberry did not vary significantly.There are significant differences of the activity of carbonic anhydrase in mulberry among treatments with different concentration of PEG 6000.PEG 6000 had little influence on net photosynthetic rate of paper mulberry,but caused significant inhibition on mulberry.No significant variation of maximum quantum yield of photosystem II(Fv/Fm)and actual photosynthetic efficiency of PS II(ΦPSⅡ)of paper mulberry among the treatments of PEG was observed,but those of mulberry were significantly inhibited by PEG.Fv/Fm and ΦPSⅡ of paper mulberry was also higher than those of mulberry.The photochemical quenching coefficient(qP)and electron transport rate(ETR)of paper mulberry was significantly higher than those of mulberry.The stable carbonic anhydrase and the strong photosynthetic capacity is an important mechanism for paper mulberry to adapt to karst-arid environment.

The photosynthetic charcteristics of the dominant plants Aegiceras corniculatum, Kandelia candel and Avicennia marina at downstream in Quanzhou Bay Estuarine Wetland on August 3, 2008 were measured, and the relationship between the photosynthetics of these plants and the climatic factors were analyzed. The results showed that the diurnal variation of net photosynthetic rates of three species of plants was three-peak curve due to tidal action. The order of the average daily net photosynthetic rate was as following: Avicennia marinaAegiceras corniculatumKandelia candel. The net photosynthetic rate of the plants was significantly correlated with their own physiological factors. There was a significant negative correlation between the net photosynthetic rate of the plants and the intercellular CO2 concentration, especially. The impact of stomatal conductance on the photosynthesis varied with plants. The net photosynthetic rates of Aegiceras corniculatum and Avicennia marina were significantly affected by stomatal conductance, and that of Kandelia candel was not affected. It was found that Avicennia marina had the adaptation to high salt environment, and sensitivity to flooding. But, Kandelia candel had the adaptation to tide changes, and sensitivity to high salt environment. The adaptation to high salt environment and flooding of Aegiceras corniculatum was intermediate between Avicennia marina and Kandelia candel.

The plant height,stem diameters,dry weights,chlorophyll contents and chlorophyll fluorescence characteristics of leaves of several vine plants,Honeysuckle,Morning glory,and Japanese creeper,which were cultured in solution at different pH level(5.2,6.2,7.2,8.2,and 9.2),were determined.The result indicated that the growth parameters and chlorophyll contents of Honeysuckle increased with the increase of pH,and reached the highest value at pH 8.2.Those parameters and chlorophyll contents of Japanese creeper reached the highest value at pH 6.2.The growth parameters except plant dry weights and chlorophyll contents of Morning glory had no significant differences with the increase of pH.Fv/Fm,Fv/F0,Fm/F0 and ΦPSⅡ in Honeysuckle increased with the increase of pH,and reached also the highest value at pH 8.2.Those of chlorophyll fluorescence parameters in Japanese creeper decreased with the increase of pH.The chlorophyll fluorescence parameters in Morning glory reached the highest at pH6.2.Subsequently,those of chlorophyll fluorescence parameters had no significant variation with the increase of pH.Thus,we can infer that Honeysuckle adapted itself to the alkalescent Karst environment(pH 8.2).

Aegiceras corniculatum, Kandelia candel and Avicennia marina are the dominant plant species of Quanzhou Bay estuarine wetland. The characteristics of chlorophyll fluorescence of plants in the wetland from different locations (upstream, midstream and downstream) at different times was studied. Initial fluorescence in Aegiceras corniculatum (0.187) was the greatest at noon, which suggested that Aegiceras corniculatum undergo large environment stress at this time. At downstream, the chlorophyll initial fluorescence of Aegiceras corniculatum in the morning (0.129) was significantly less than that in the afternoon (0.173), and that of K.candel in the morning (0.142) was also significantly less than that in the afternoon (0.171). The maximum quantum yield of Aegiceras corniculatum and K.candel, 0.795 and 0.799 respectively, was significantly higher than that of each plant species in the afternoon. It suggested that the environmental stress on the plants in the morning was less than that in the afternoon at downstream. The curves of chlorophyll fluorescence in response to photosynthetically active radiation showed that the photosynthetic potential and the capture light energy efficiency of the Aegiceras corniculatum in the morning were lower than those in the afternoon. At downstream, the photosynthetic potential and the capture light energy efficiency of Aegiceras corniculatum in the morning was the highest. Mature K.candel in the afternoon was provided with the highest the photosynthetic potential and the capture light energy efficiency. The photosynthetic potential and the capture light energy efficiency of the 5-year-old K.candel in the morning was the least at upstream. Mature Aegiceras corniculatum, K.candel and Avicennia marina were provided with good adaptability.

The seasonal urease and phosphatase activities in the soil under different mangrove plants and upon different plots (upstream,midstream and downstream)at Quanzhou Bay estuarine wetland were studied.The main results were as follows:There was significant correlation between the soil urease and phosphatase activities,which showed no significant difference upon different plots.The urease and phosphatase activities in the soil were higher in spring than autumn,which under mangrove plants were all higher than those in the New alluvial soil without plants and Bared land.Soil uresse activity exhibited no significant difference under different mangrove species.The phosphatase activity in the soil of Centenary Aegiceras corniculatum(CA) and Spartina alterniflor(Sa)was the highest,which was the higher in the soil of Kandelia candel(Kc)and Avicennia marine (Am).The two soil enzyme activities generally decreased with increasing soil depth,and those in the soil at Quanzhou Bay estuarine wetland were closed relation to the plant species and root distribution.of the mangrove forest.These findings offered a theoretical foundation for the environmental protection and ecological restoration of Quanzhou Bay estuarine wetland.