Study On The Spatial Patterns Of Leaf Traits Of Hippophae Tibetana And Their Response To Environmental Change

Leaf is the most basic elements of terrestrial ecosystem function. It is the mainorgan about the plant photosynthesis and production of organic matter, and the mainorgan about gas and water exchange between plant and atmospheric environment.Leaf traits, a comprehensive index to measure the internal physiologicalcharacteristics of plant and external environment, embodies the survival strategies ofplant corresponding outside environment. The complicated geography and changeableenvironment in Qinghai-Tibet Pleatu provided a opportunity to explore the responseof leaf traits to environmental change. Hippophae tibetana is a species endemic toQinghai-Tibet Pleatu and distributed areas at2800-5200m. It has the ability adapted tothe environment that gradually becomes arid and cold with the arising ofQinghai-Tibet Pleatu. In the present paper, H. tibetana was selected an materials and22populations were collected from different sample sites in the eastern of Qinghai-Tibetan Plateau. The leaf traits of H. tibetana, including leaf size, leaf area, specificleaf area(SLA) and stomatal density(SD) as well as δ13C values, were measured andthe relationship between leaf traits and environmental factors (altitude, longitude andlatitude, the average annual precipitation, annual average temperature) were analyzed.The aims are to detect the change of leaf traits with the change of space andenvironment, and to explore adaptation of H. tibetana to the changeable environmentin Qinghai-Tibet Pleatu. The results show as follows:(1) LW and LA of H. tibetana are significantly negative related to the altitude (P<0.01), LL/LW is positive related to the altitude, while LL of H. tibetana has nocorrelation with altitude, SLA and SD of H. tibetana firstly increase then reduce withaltitude increasing according to regression analysis. It shows that H. tibetana tend todevelop into narrow leaf in high altitude. It means that the middle altitudes is suitablefor H. tibetana to live due to the appropriate temperature and humidity.(2) LL, LW, LA and SD of H. tibetana are significantly positive related to thelongitude (P<0.01), SLA is significantly negative related to the longitude (P<0.01),LL/LW has no significant correlation with longitude (P≥0.05). LL and LL/LW arenegative related to the latitude, but LW and SLA are positive related to the latitude,LA, SD firstly increase then reduce along latitude increasing according to regression analysis. Because the difference of temperature and precipitation in different latitudeand longitude, so the leaf traits of H. tibetana are mainly response to the temperatureand precipitation. It is said that H. tibetana in the study area is mainly affected byprecipitation to adapt to the local habitat.(3) LL, LA and LL/LW of H. tibetana are significantly positive related to theaverage annual precipitation (P <0.01), SLA is negative related to the average annualprecipitation, and LW firstly reduce then increase with average annual precipitationincreasing according to regression analysis. However, SD has no significantcorrelation with average annual precipitation. It indicated that the smaller leaf of H.tibetana adapted to drought environment and the leaf of H. tibetana more sensitive tothe precipitation.(4) LL, LA and LL/LW are significantly increase with increasing of temperature(P <0.05), SLA, SD both have a very significantly negative correlation with averageannual temperature (P<0.01). No significant correlation between LW with averageannual temperature. The trends that SLA, SD of H. tibetana decrease with increasingof temperature may a strategy of H. tibetana adapted to change of temperature.(5) δ13C values in H. tibetana are-28.84‰~-26.18‰, and the mean value is-27.48‰. It indicated that H. tibetana belongs to C133plant, and the range of δCvalues in H. tibetana is relatively narrow. At same time, δ13C values of H. tibetana islower than other plants in the world, the results suggests that H. tibetana doesn’tbelong to the plant of high water use efficiency.(6) δ13C values of H. tibetana has no correlation with latitude, a very significantpositive correlation with altitude, and a extremely significant negative correlation withlongitude (P <0.01). δ13C values of H. tibetana has a significant negative correlationwith annual average temperature, but its relationship with annual average precipitationis complex. With the increase of average annual precipitation, δ13C values of H.tibetana is firstly rising then falling. It is said that the δ13C values of H. tibetana isprimarily affected by temperature rather than water.(7) δ13C values in H. tibetana is extremely significant negative related to LL, LW,LA and SD. δ13C values of H. tibetana firstly reduce then increase with LL/LWincreasing, and it firstly increase then reduce with SLA increasing. It is said that leaf size and SD of H. tibetana are main factors influencing on δ13C values of H. tibetanain this study areas.