【作者】 胡启鹏；

【导师】 马履一； 郭志华；

【作者基本信息】 北京林业大学 ， 森林培育， 2008， 硕士

【摘要】 长白山森林生态系统是中国东北样带(Northeast China Transect,NECT)上最典型的植被垂直梯度分布,是植被水平分布典型的缩影,但目前还没有对整个海拔梯度植被分布特征的内在研究。而亚高山岳桦林带是从森林过渡到苔原的一个过渡带,具有较高的研究价值,但对其进行的研究较少,在全球大气变化的影响下,过渡带的森林是如何响应和适应异质环境,是如何在生理和叶特征上调整应对高海拔环境驱动,这些均具有非常重要的生态学意义,也有利于我们在个体层次上,从生理生态的角度深入认识和理解岳桦林的群落动态与演替的内在驱动机制,为长白山整个生态系统的研究提供依据。本试验以长白山亚高山岳桦林带建群树种岳桦为主要研究对象,研究岳桦林的叶特征和光合生理特征,测定了岳桦海拔分布的气候情况,岳桦幼树的叶形态特征、光响应、CO2响应,以及成年树的形态特征、土壤理化性质和养分随海拔梯度的变化规律,结果表明:1、随海拔梯度增加,气温、降雨量、风速及紫外线辐射强度逐渐增强,湿度在林内逐渐下降,但苔原带的湿度较岳桦纯林高,较混交林低,这可能与苔原带降水量与风速都较大的原因。8月上旬是岳桦林的生长旺季,此月份内,气温、湿度、风速及降雨量均明显增加,且7月多以西北偏北和东北偏北为主,8月以西北风为主。岳桦生长的土壤条件为酸性土壤,pH值呈先下降后升高变化,在海拔1800m左右达到极小值,土壤含水量随海拔梯度增加而增加,土壤容重与pH值变化一致,而土壤空隙度却相反;有机质含量及全氮含量也呈下降后升高变化,均在海拔1800m附近出现极小值。正是气候与土壤的综合作用,以致形成岳桦目前的这种分布格局。2、随海拔梯度升高,岳桦叶面积逐渐下降,但在海拔1700m～1900m内叶片最薄,叶绿素Chl与叶氮含量Narea变化相反,后者在海拔1700m～1900m范围内最小,植物将更多的氮分配到了光合器官(叶绿素)中;类胡罗卜素Car与抗氧化物质脯氨酸Pro、抗坏血酸过氧化物酶活性APX及可溶性糖含量DS变化一致,但与过氧化产物丙二醛MDA恰好相对应,表明随海拔升高,环境胁迫越来越严重,过氧化作用越来越明显,但同时岳桦的抗胁迫机制也得到了有效进化,较高的生化、生理可塑性表明岳桦依赖生理作用比依赖叶形态来调节适应机制更重要。3、岳桦幼树的最大净光合速率Pmax、表观量子产量AQY、羧化效率CE、光能转化效率δ、最大羧化速率Vcmax及最大电子传递速率Jmax均呈现增加后降低变化,在海拔1700～1900m达到最大值,而光补偿点LCP和CO2补偿点CCP则相反,在上述海拔范围内具有最小值,表明岳桦的起源可能从海拔1700m～1900m开始,光合活性最强,然后向下或向上发展;同时,暗呼吸速率Rd与光呼吸速率Rday光能利用效率SUE变化一致,均呈一次正相关,叶绿素荧光Fv/Fm值均在0.8以上,表明在岳桦的分布范围内,光合作用并未受阻,但胁迫越来越强烈,以致形成目前的这种分布格局,并随着气候变化这种格局将会继续变化。4、随海拔梯度增加,岳桦的密度总体呈增加趋势,树高和胸径呈总体下降趋势变化,但在海拔1800m附近均表现出一个较大的起伏,密度在此海拔骤然增高,随后下降又呈逐渐增加变化,而树高则没有变化,胸径在此海拔以后,下降幅度较大,所以,海拔1800m可作为岳桦分布的一个分水岭,这恰好在光合生理活性最高的海拔范围(1700m—1900m)内,因此,海拔1800m可确定为岳桦起源的起点。与低海拔岳桦相比较,虽然云杉林通过较低的枝下高和较大的冠幅来获得较多的光能,但其较低的树高和胸径可以说明,相对较高的海拔环境已不适应其生存发展,同时低海拔更体现出了岳桦较高的对光强的依赖性;与高海拔落叶松相比,其较高的胸径和树高表明了其适应性较强,但存活率较低,这说明落叶松是以高的死亡率来换取生存,同时在整个岳桦分布范围内,草本植物牛皮杜鹃一直伴生,且生长高度变化相一致,可以很好地作为岳桦的指示植物。更多还原

【Abstract】 Forest ecology system of Changbai Mountain, belonging Northeast China Transect (NECT), is most typical vegetation with vertical distribution and images a vegetation distribution along level, but there is black in systematical research from whole altitude so far. Although B. ermanii is a sub-alpine transition belt from forest to alpine tundra and has higher study value ecologically, little work has been done. Especially under the effect of global climate change, plants in above line of forest are how to respond and acclimate to heterogeneous environments, and how to adjust to challenge climatic changes physiologically and morphologically, which ecologically offers to a very important significance, and moreover, make for us understanding deeply in the terms of the regeneration of forest, the dynamic of community and the intrinsic drive-mechanism of succession on the individual level. Thus, these are able to base for study systematical for Changbai Mountain. In this dissertation, sub-alpine building population B. ermanii was selected as experimental material and studied in characteristics of morphological and physiological changes along altitude of, including climatic condition, leaf morphological traits and light response and CO2 response of saplings, and quantitative traits of mature, and soil physical-chemic properties and nutrient. The following results could be achieved:1.Climatic index including air temperature, precipitation, wind speed and ultraviolet radiation intensity enhanced gradually along altitude. Although humidity declined within forest, however, it was higher in tundra than that in pure forest of B. ermanii, and it was lower in tundra than that in mixed forest, which was likely to due to greater precipitation and wind speed in tundra. The first ten days of August was the growth season, because in this period the temperature, humidity, wind speed precipitation increased markedly. And wind direction generally was northwest leaning north and northeast leaning north in July, and northwest in August. The soil condition of distribution of B. ermanii generally was acidic. The pH was less than 7.0 and reached minimum at 1800m. Soil water content being related with more precipitation was linear along altitude. Soil density varied congruously with pH, but the pertinence was reverse. Soil organic material content and entire nitrogen content had minimum at 1800m. It was just climatic and soil difference that resulted in a recent distribution partern. 2 . With the altitude, Leaf area decreased and became most thin between altitude 1700m—1900m; Chlorophyll was opposite to the changes of leaf nitrogen with a minimum between altitude 1700m～1900m, which suggested B. ermanii invested more nitrogen to chlorophyll in this altitude (NChl); The variation of carotenoid accorded with antioxidant material Pro, APX, DS whereas, countered oppositely with MDA, one of main products resulted from activated oxygen, which illustrated that B. ermanii evolved effectively antioxidant system when inhibition became bad and bad with increased altitude. Higher antioxidant and physiological plasticity value showed B. ermanii depended on more physiological than morphological to adjust to acclimation.3.Maximum net photosynthetic rate Pmax, apparent quanta yield AQY, carboxylation efficiency CE, photosynthetic energy transformation efficiencyδ, maximum carboxylation rate Vcmax and maximum electronic transfer Jmax of saplings of B. ermanii increased and then decreased with altitude, exhibiting maximum in 1700m～1900m, but light compensation point LCP and CO2 compensation point CCP were reverse, and obtained minimum in the same altitude range. It could be concluded that origin of B. ermanii was from1700m—1900m altitude with most active photosynthesis, and developed adown or upwards. Dark respiration rate Rd, light respiration rate Rday and solar energy use efficiency SUE were positively linear with increased altitude, and maximum photochemistry efficiency Fv/Fm was higher than 0.8, which suggested photosynthesis of B. ermanii was not suffered from stress among its distribution range, however, the stress was stronger and stronger with increased altitude and thus led to current distribution pattern which will continue varying under the effect of global change.4.With the altitudinal gradient increasing, while density of B. ermanii generally increased and height and breast diameter decreased, they all showed a fluctuation in 1800m around that the density increased abruptly and then declined and increased again, height was no change, and the breast diameter fell in a great degree from 1800m. This altitude thus could be regarded as a watershed of distribution which even belonged to distribution range of highest activity of photo-physiology of B. ermanii, so the altitude 1800m could be cognized as its original point. Compared with B. ermanii in low altitude, although Picea jezoensis could obtain more light through lower branch height and greater crown, less height and breast diameter showed hard to acclimate the high latitude environment. At the same time, low altitude reflected higher dependent on light for B. ermanii. Compared with B. ermanii in high altitude, the greater breast diameter and height of Larix olgensis showed its stronger flexibility, but its survival exchanged with high death rate. Among distribution range of B. ermanii, the herbage Rhododendron aureum accompanied all along and the change of growth height was consistent with B. ermanii, which could better served as indication plant for B. ermanii.更多还原