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During the long-term processes of evolution and development, plant species yield a set of morphological, structural and physiological characteristics through their interactions with the environment, and these characteristics indicate their ecological adaptive strategies to the environment Within forest communities, topographic and edaphic variations often lead to habitat heterogeneity, and hence tend to directly or undirectly influence the distribution pat- terns of plant species. Thus, it is an important question that how plant species distribution is related to its ecological adaptive strategies in forest commnuties with high habitat heterogeneity. Ardisia quinquegona and Aidia canthioides are two dominant evergreen tree species in the subtropical monsoon evergreen broad-leaved forest within the 20 ha forest biodiversity monitoring plot at Dinghushan National Nature Reserve in Zhaoqing City, Guangdong Province, China. The two tree species are distributed in different habitats including mountain ridge, slope, and valley. To under- stand the relation of their ecological strategies of habitat adaptation to their distribution patterns in the forest, a comparative study was conducted on their leaf functional traits and hydraulic properties among the three different habitats. Functional traits measured include leaf area (LA), leaf thickness, leaf length/leaf width ratio, specific leaf area (SLA) , and leaf dry matter content (LDMC) , while hydraulic properties include sapwood specific hydraulic conductivity, leaf specific conductivity, huber value, wood density (WD) , leaf water potential at turgor loss point (r°) and saturated leaf water potential (π100) The results showed that A. quinquegona tended to adapt to different habitats mainly through the ad] ustment of leaf area LA, WD and osmotic regulation. In contrast to A. quinquegona, A. canthioides had a stronger ability to adapt to the environment, especially mountain ridge and slope habitats, via the strategy of "slow growth rate and high survival rate". It mainly made fine adjustment on SLA,WD and osmotic regulation, and used the strategy of efficient conservation of nutrients (low SLA, high LDMC). Moreover, the soil factors that limit leaf functional traits and plant hydraulics differed between the two studied tree species. Our results revealed that both species were suitable to survive in mount ridge and slope rather than in valley, while they differed in habitat adaptation strategies regarding leaf functional traits and hydraulic properties, although they both were dominant species in the subtropical monsoon evergreen broad-leaved forest. [ABSTRACT FROM AUTHOR]

[Objective] The high-quality pasture species suitably interplanted with Mangifera indica in Southern China were screened in order to provide scientific references for establishing efficient utilization model of artificial grassland in M. indica orchard of Southern China. [Method]The allelopathic effects of aqueous extract from M. indica leaves at five different concentrations (1.00 % , 0.50 % , 0.20 % , 0.10 % and 0.05 % ) on six important pasture species (viz. Macroptilium atropureum, Lupinus polyphyllus, Medicago sativa L., Stylosanthes guianensis Reyan 2, Paspalum atratum Reyan 11 and Lolium perenne L) and two mode receptor plants (Glycine max L and Oryza glaberrima) were investigated by biological assay. [Result] Except that several receptor plants showed allelopathic promoting effect of aqueous extract from M. indica leaves at low concentration, most of receptor plants showed obvious allelopathic inhibiting effect. Moreover the inhibiting effect became greater with increasing concentration of aqueous extract. Therefore, the allelopathic synthesis effects of aqueous extract from M. indica leaves were different among tested receptor plants. As for all tested pasture species in M. indica orchard , their adaptability from strong to weak in order was L. polyphyllus>M. sativa> S. guianensis>M. atropureum in leguminosae and L. perenne>P. atratum in gramineae. [Conclusion] L. polyphyllus and L. perenne are two most preferable interplanting pasture species in M. indica orchard, and specific attention should be paid to timely prevent and kill off weeds, water and fertilize suitably in field management. [ABSTRACT FROM AUTHOR]

The efficacy of a biological control agent depends upon the impact it has on the target species. We investigate the use of the obligate parasitic plant, Cuscuta campestris Yuncker as a biological control for the invasive weed Mikania micrantha H.B.K. In this experiment we test whether the impacts of the parasite on host growth, biomass allocation, photosynthesis, chlorophyll content, and soluble protein are affected by the density of the parasite. We examined the response of M. micrantha to infection densities of 0, 1, 2, 4 and 8 C. campestris seedlings per host plant. By day 30 after parasitization, C. campestris infection had significantly reduced M. micrantha biomass and the net photosynthetic rate of the 8th fully expanded leaf. These negative effects were greater as the number of parasites increased from 1 to 4 per host, but not from 4 to 8. Mikania micrantha stomatal conductance and transpiration rate were significantly reduced by C. campestris infection, but among 2, 4, 8 parasites per host there were no significant effects of infection densities on the host plants. Water use efficiency remained stable. The aerial parts of the infected M. micrantha plants at densities of 1, 2, 4 and 8 parasites per host died 83, 62, 50 and 46 d after parasitization on average, respectively. All infection densities decreased host chlorophyll content (a and b), and the infection by more than 1 parasite also significantly lowered soluble protein concentration. The results indicated that the effects of C. campestris infection on M. micrantha are density dependent, which provides a basis for refining the use of the parasite for biological control of M. micrantha. The optimal cost-effective number of parasites to control M. micrantha is 4 per host plant in the field. [ABSTRACT FROM AUTHOR]