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Employing Granierś probes, this paper measured the sap flow of 14 sample trees in an Acacia mangium forest on the Heshan hilly lands of Guangdong Province, and recorded the photosynthetic active radiation (PAR), air relative humidity (RH) , and air temperature (T) above the forest canopy. The whole-tree transpiration (E), stand transpiration (Et), and mean canopy stomatal conductance (gc) were calculated, and the relationships between tree morphological characters and whole-tree water use as well as the responses of gc to PAR and vapor pressure deficit (D) were analyzed. The results showed that the whole-tree transpiration had logarithmical positive correlations with tree diameter at breast height (DBH) (P < 0.0001) , sapwood area (P < 0.0001) and canopy size (P = 0.0007), and an exponential positive correlation with tree height (P = 0. 014). The maximum gc (gc max) changed with PAR hyperbolically (P < 0.0001), and with D logarithmically (P < 0.0001). The sap flow measurement system used in this study was reliable and accurate in estimating the transpiration of whole-tree and stand and the canopy stomatal conductance, being an effective tool in studying the relationships between forest water use and environmental factors.

In this study, potted C. burmannii saplings were cultured in a top-closed chamber with elevated CO2 (+ CO2, 731 micromol x mol(-1)) and ambient CO2(CO2, 365 micromol x mol(-1)), and at diurnal temperature (day/night) 25/23 degrees C and 32/25 degrees C, respectively. The gas exchange, calculated photosynthesis parameter, Rubisco content, and activated state of Rubisco were examined. The results showed that under + CO2 and at 25/23 degrees C, the mean photosynthetic rate (Pnsat) of sapling leaves was 5.1% higher than that under + CO2 and at 32/25 degrees C. Temperature enhancement declined Pnsat, while nitrate addition increased it. Under + CO2, saplings had lower V(cmax) and J(max) at 32/25 degrees C than at 25/23 degrees C. Temperature enhancement under + CO2 also declined V(cmax) and J(max). Under + CO2, lower photorespiration rate (Rp) occurred in leaves, but temperature enhancement could increase Rp. Under + CO2, Rubisco content (NR) and its active site per unit leaf area (M) decreased as diurnal temperature changed from 25/23 degrees C to 32/25 degrees C. Meanwhile, nitrate addition could increase NR and M. It may be suggested that nitrate addition could alleviate the restriction of photosynthesis under elevated CO2 concentration and enhanced temperature.

Wikstroemia indica was the common shrub with medicine use in subtropical and tropical zones. The studies on the biological and physiological characteristics, population dynamics, biomass, nutrient composition of Wikstroemia indica showed that Wikstroemia indica was widely dispersed over hilly lands and opened forests. It was heliophytes and grew well on improverished soil. Its average photosynthetic rate and conductance were 7.33 mumolCO2.m-2.s-1 and 0.042 molH2O.m-2.s-1, respectively. The weighted nutrient concentration of Wikstroemia indica were N 0.667%, P 0.081%, K 0.540%, Ca 0.776%, and Mg 0.259%, respectively, and the medicine ingredient was Wikstroemine C16H12O5. Due to morphological difference, the competitive power on energy and nutrient of Wikstroemia indica was less than that of Rhodomyrtus tomentosa. Wikstroemia indica population decreased, while Rhodomyrtus tomentosa increased on shrubby grass land during early successional stage. Wikstroemia indica could be planted to increase its biomass to exploit medicine use.

Mining activities usually cause catastrophic and extensive environmental changes, and eventually cause major damages to the whole ecosystem. The natural restoration for mine lands and tailings is a very slow process, and even can hardly reach their original states. Therefore, how to develop rapid and efficient approaches to accelerate restoration of mined lands has been highlighted by restorationists and environmental engineers during the past two decades. Almost all studies in this field indicate that the major problems come from soils: such as high metal concentrations, extremely strong acidity resulting from oxidation of pyrite, and poor fertility. Replacement of topsoil is therefore regarded as the most efficient method to alleviate adverse conditions of substrates; if this method is not available, other alternatives with lime, fertilizers, organic manures, garbage, mining wastes, and others will be applicable. In the aspect of using plants, species with strong resistance and rapid growth, like grasses and herbaceous legume, are always the first choice. If utilizing plants for the purpose of phytoremediation, species that are capable of accumulating exceptionally high concentrations of phytotoxic metals and of course, have a huge biomass, are preferably considered. No matter what type of ecosystem a mined land is restored or reclaimed to, an evaluation on whether it is a successful restoration or reclamation should be given. However, more practical, simple, and universal evaluation methods as well as more cost-effective, and operation-easy restoration techniques are still waiting to be developed. A set of artificial restoration methods that can be widely applied was summarized, and a discussion on the advantage and disadvantage of several evaluation systems was conducted in this review.