积雪变化对高寒草甸钝苞雪莲(Saussurea nigrescens)繁殖分配及功能属性的影响

季节性雪被对植物的生长繁殖具有深刻影响。为阐明不同积雪梯度下钝苞雪莲各器官生物量、养分含量、繁殖分配及功能属性的变化规律，在青藏高原东缘红原县，通过人工堆积的方法开展积雪梯度（CK、S0、S1、S2、S3）控制实验，测量了不同积雪梯度下钝苞雪莲茎、叶、花苞的养分含量及繁殖分配等特征。结果表明：1）积雪变化没有显著改变钝苞雪莲的繁殖分配，但去除积雪（S0）显著降低了营养器官生物量。2）不同积雪处理下，个体大小与繁殖器官生物量均呈正线性关系（P<0.01）。3）茎部磷（P）含量随积雪量的增加显著升高（P<0.05）；叶部P含量随积雪量的增加先上升后下降，即：S2 > S1 > CK > S3 > S0，且存在显著差异（P<0.05）；各处理下植物的不同器官在养分上主要受氮（N）元素的限制。4）去除积雪（S0）降低了茎干重、株高、茎高、茎分配和单株花苞量，过度积雪（S3）则降低了株高、茎高和花苞长度，中度积雪（S1、S2）则分别降低了花苞长度与单株叶片数。由此可见，不同积雪量并未显著改变钝苞雪莲的繁殖分配，但却改变了其不同器官的功能属性与养分含量，使磷元素成为植物响应积雪变化较为敏感的指标。

Effects of snow cover changes on reproductive allocation and functional traits of Saussurea nigrescens in alpine meadow

The seasonal snow cover has a profound effect on plant growth and reproduction. In order to clarify the change rule of each organ biomass, nutrient content, reproductive allocation and functional traits of Saussurea nigrescens under different snowpack. Our experimental site is located in Hongyuan County, the eastern margin of the Qinghai-Tibetan plateau. Control experiments of snow gradient (CK, S0, S1, S2, and S3) were carried out by manual accumulation. The characteristics of stem, leaf and fruit nutrient content and reproductive allocation were measured by indoor analysis method under different snowpack. The results showed that:1) the change of snowpack did not significantly change the reproductive allocation of Saussurea nigrescens, but the removal of snow cover (S0) significantly reduced the biomass of vegetative organs. 2) Under different snow cover treatments, there was a positive linear relationship between individual size and reproductive organ biomass (P<0.01). 3) The content of phosphorus (P) in stem increased significantly with the increase of snow cover (P<0.05). With the increase of snow cover, the content of P in leaves first significantly increases and then decreases, which is presenting as S2 > S1 > CK > S3 > S0. Different organs of plants under different treatments were mainly limited by nitrogen (N) element. 4) Removal of snow cover (S0) reduced stem biomass, plant height, stem height, stem allocation and individual fruit number; the excessive snow cover (S3) reduced plant height, stem height and fruit length; the moderate snow cover (S1 and S2) respectively reduced fruit length and individual leaf numbers. Therefore, different amounts of snow cover did not significantly change the reproductive allocation, but changed the functional traits and nutrient content of different organs.