Ecological Adaptive Strategy Of Genus Rhododendron L.in Eastern Qilian Mountains Alpine Ecosystem

AbstractEcological adaptive strategy of four species Rhododendron in Eastern QilianMountains was studied systematically by the morphology, life history, verticaldistribution of populations and physiological ecology. Effect of ecological factorwas analyzed by transplanting. The adaptation of Rhododendrons was also studiedby a method of weak electric signal at first time. The similarities, differences andmechanism were discussed on the level of protein and DNA, at first time usingelectrochemical analysis in plant DNA, and complex as probe in it. A proposal ofprotecting and utilizing to Rhododendron in Eastern Qilian Mountains was bringforward.Ecological adaptive strategy of the four species of Rhododendron in EasternQilian Mountains reflected the adaptation to coldness and physiological drought.These feature as follows: 1. Plants grow low and dense. 2. There are squama andcutin on young branch, leaves and buds, excreting resin producing volatile oilfrom these organs too; 3. Roots grow slender and dense, distributing amongO?Ocm deep in the soil. 4. The too lower temperature or freezing of soil is mainreason that roots can not absorbing water easily, then water content reducing, andthe leaves began to roil reversely. 5. There is obvious interrelationship betweenperiodic variation of water content and physiological action; leaves keep water bycoiling reversely, spend winter by coiling tightly in shape of stick or canal. 6.Growing season is short, dormant period is long; vegetative growth andreproductive growth are synchronous during a same short period; July is the keymonth of life history of these Rhododendron species; water contents of branch andleaves get maximum value, leaves expansion without coiling, photosynthetic rateare higher, the growth of young branch is 60?0% of one year. 7. Rhododendronseedling is rare in the alpine shrub, the main propagation style are vegetativemultiplication by tiller. The young plant lives vigorously, which is the maincontributor of community biomass. There are some difference among four speciesin leaf area, density of squama. thickness of cutin, the pattern and degree, periodof sprouting, trend of water content, net photosynthetic rate, et.al. The differenceof morphology, life history and physiology increase from R. thym~folium and R.cap itatum, R. ant hopogonoides to R. prezewalski, and difference between R.prezewalsk and other three species are great.Overlapping and separation of niche can explain the vertical distributionstrategy of four Rhododendron species on elevation on northern slope of easternQilian Mountain. Below alt.3300m of the northern slope, it is occupied mainly by11R.thymzfolium and R. capitatum. R. prezewalskii become the dominant species up3300m, the cover of R. anthopogonoides get maximum at alt. 340Gm, associatedwith R. thym?folium and R. cap itatum downward, company with R. prezewalskiiupward.Adaptation behavior after transplanting, the soluble protein content in leaves,and model analysis shows that the unadaptation is the result of all factors that aredifferent with the original environment, but the temperature is the key factoraffected the success of potted indoors. Adaptability of R. thymjfolium, R.capitatum, R. anthopogonoides and R. prezewalskii are increasing by the order.The last two species of Rhododendron have hope of domestication. The sameresults had been gotten from the wake electric signal analysis in water culture ofRhododendron branches. R. prezewalskii is more adaptive to high temperatureenvironment than the other species of Rhododendron, The range of adaptation of R.thym~folium and R. capii~atum are weak.The difference of DNA of these Rhododendron species is the hereditary basisof similarities or differences in the adaptive strategy. The adapti...