Lilles Erica B, Astrup Rasmus, Lefrançois Marie-Lou, David Coates K
Bulkley Valley Centre for Natural Resources Research and Management, Box 4274, Smithers, BC V0J 2N0, Canada
Bulkley Valley Centre for Natural Resources Research and Management, Box 4274, Smithers, BC V0J 2N0, Canada Norwegian Forest and Landscape Institute, Høgskoleveien 8, Postboks 115, 1431 Ås, Norway.
Tree Physiol. 2014 Dec;34(12):1334-47. doi: 10.1093/treephys/tpu092. Epub 2014 Nov 23.
We developed models to describe the responses of four commonly examined leaf traits (mass per area, weight, area and nitrogen (N) concentration) to gradients of light, soil nutrients and tree height in three conifer species of contrasting shade tolerance. Our observational dataset from the sub-boreal spruce forests of British Columbia included subalpine fir (Abies lasioscarpa [Hook.] Nutt; high shade tolerance), interior spruce (Picea glauca × Picea engelmannii [Moench] Voss; intermediate shade tolerance) and lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia; low shade tolerance) saplings from 0.18 to 4.87 m tall, in 8-98% of total incident light, from field sites with <17.6 kg ha(-1) to >46.8 kg ha(-1) total dissolved N. Leaf weights and areas showed strong positive responses to light and height, but little or no response to soil nutrients. Parameter estimates indicated that the shape of leaf weight and area responses to light corresponded with shade tolerance ranking for the three species; pine had the most linear response whereas spruce and fir had asymptotic responses. Leaf N concentration responded positively to soil nutrients, negatively to light and idiosyncratically to height. The negative effect of light was only apparent on sites of high soil nutrient availability, and parameter estimates for the shape of the negative response also corresponded to shade tolerance ranking (apine = -0.79, aspruce = -0.15, afir = -0.07). Of the traits we measured, leaf mass per area showed the least response to light, soil nutrient and height gradients. Although it is a common practice in comparisons across many species, characterizing these conifers by mean values of their leaf traits would miss important intraspecific variation across environmental and size gradients. In these forests, parameter estimates representing the intraspecific variability of leaf trait responses can be used to understand relative shade tolerances.
我们构建了模型，以描述三种耐荫性不同的针叶树种中，四个常用的叶片性状（单位面积质量、重量、面积和氮（N）浓度）对光照、土壤养分和树高梯度的响应。我们来自不列颠哥伦比亚省亚寒带云杉林的观测数据集包括亚高山冷杉（Abies lasioscarpa [Hook.] Nutt；高耐荫性）、内陆云杉（Picea glauca × Picea engelmannii [Moench] Voss；中等耐荫性）和黑松（Pinus contorta Dougl. ex Loud. var. latifolia；低耐荫性）的树苗，树高从0.18米到4.87米，总入射光的比例为8 - 98%，来自总溶解氮含量低于17.6千克/公顷至高于46.8千克/公顷的野外场地。叶片重量和面积对光照和树高表现出强烈的正响应，但对土壤养分几乎没有响应或无响应。参数估计表明，叶片重量和面积对光照的响应形状与这三个树种的耐荫性排名相对应；松树的响应最呈线性，而云杉和冷杉的响应呈渐近线。叶片氮浓度对土壤养分呈正响应，对光照呈负响应，并对树高表现出特异响应。光照的负面影响仅在土壤养分有效性高的场地明显，负响应形状的参数估计也与耐荫性排名相对应（松树 = -0.79，云杉 = -0.15，冷杉 = -0.07）。在我们测量的性状中，单位面积叶片质量对光照、土壤养分和树高梯度的响应最小。尽管在跨多个物种的比较中这是一种常见做法，但用叶片性状的平均值来表征这些针叶树会忽略环境和大小梯度上重要的种内变异。在这些森林中，代表叶片性状响应种内变异性的参数估计可用于理解相对耐荫性。
