Abstract:

Plant leaf functional traits can reflect their adaptive strategies to different environmental gradients, producing adaptive changes to different environmental gradients. In this study, the dominant plants of four planting cover types (desert steppe, shallow-mountain shrub, subalpine coniferous forest and subalpine shrub meadow) distributed along the western slope of Helan Mountain were selected as the object. At the species-community level, the ecological strategy model based on the leaf functional characteristics of CSR (Competitor-Stress tolerator- Ruderal) was established. We explored the economic character tradeoff strategy of the S-R axis of the dominant plant types and the ecological strategy composition of the dominant species by comparing the leaf specific leaf area (SLA), leaf dry matter content (LDMC), carbon (LC), nitrogen (LN) and phosphorus (LP) contents per unit area. In addition, we determined the main environmental factors, affecting the CSR ecological strategy of plants, through the mechanism investigation of environmental factors on CSR ecological strategy. The results showed that: 1) At the species level, forty-six dominant plant ecological strategies on the western slope of Helan Mountain could be divided into five categories, with R (weed type) and SR (tolerance-weed type) prevalent (52.1% and 23.9%, respectively). 2) At the community level, thirty plots were divided into 5 ecological strategies, and the dominant strategy was R (weed-based strategy), accounting for 39.2%. 3) There was a significant negative correlation between S strategy and specific leaf area; R strategy had significant negative correlations with total phosphorus, total carbon, and leaf dry matter content, and had significant positive correlation with specific leaf area. 4) Elevation ALT, annual mean temperature MAT, annual mean rainfall MAP, solar radiation SRAD and vapor pressure VAPR have significant effects on the C strategy, and the C strategy decreases with the increase of altitude. Soil TP was positively correlated with S strategy and negatively correlated with R strategy. This study shows that plants can change functional traits (such as specific leaf area, leaf carbon, nitrogen and phosphorus content), change resource availability and material allocation, and adapt to different environments, thus forming different ecological strategies.

Key words: Helan Mountain, elevation gradient, plant functional traits, ecological strategy, vegetation type

摘要：

植物叶片功能性状能够反映其对不同环境的适应策略，对不同环境梯度产生适应性改变。以贺兰山西坡沿海拔分布的4种植被类型（荒漠草原、浅山灌丛、亚高山针叶林、亚高山灌丛草甸）优势植物为对象，在物种-群落水平，基于叶片功能特征CSR（竞争-耐胁迫-杂草型植物）生态策略模型，通过叶片比叶面积（SLA）、叶干物质含量（LDMC）、单位面积碳（LC）、氮（LN）、磷（LP）含量的比较，探究4种植被类型优势植物S-R（耐胁迫-杂草）轴的经济性状权衡策略及该区优势种的生态策略组成；并且研究环境因素对CSR生态策略的作用机理，确定能够影响植物CSR生态策略的主要环境因子。结果显示，1）在物种水平，贺兰山西坡46种优势植物生态策略可分为5类，其中R（杂草型）和SR（耐胁迫-杂草型）策略为主导策略，所占比例分别为52.1%和23.9%。2）在群落水平，贺兰山西坡30个样地生态策略划分为5类，主导策略为R（杂草型策略），占比39.2%。3）S策略与比叶面积显著性负相关关系；R策略与全磷、全碳、叶干物质含量显著性负相关关系，和比叶面积显著性正相关关系。4）海拔、年均温、年均降雨量、太阳辐射、水蒸气压对C策略有显著影响，随海拔上升C策略降低。土壤全磷与S策略正相关，与R策略负相关。该研究表明植物能够改变功能性状（如比叶面积、叶片碳、氮、磷含量），改变资源获得能力和物质分配，应对不同环境，从而形成不同的生态策略。

关键词: 贺兰山, 海拔梯度, 植物功能性状, 生态策略, 植被类型