At high elevation or latitude, trees reach low-temperature range limits. In attempting an explanation, the range limits of individual tree species (set by freezing tolerance) and the general limit of the life-form tree (set by thermal growth constraints) need to be distinguished. The general cold edge of the fundamental niche of trees is termed the treeline, by definition, the lower edge of the alpine belt, a most important bioclimatological reference line. Trees can be absent from the treeline due to disturbances or biotic interactions. The actual local edge of tree distribution, the delineation of the realized niche, is driven by stochastic effects. Therefore, treeline theory and hypothesis testing is inevitably tied to the fundamental niche concept.

在高海拔或纬度，树木达到低温范围限制。在尝试解释时，需要区分单个树种的范围限制（由耐寒性设定）和生命形式树的一般限制（由热生长限制设定）。树木基本生态位的一般冷边缘被称为树线，根据定义，高山带的下边缘是最重要的生物气候参考线。由于干扰或生物相互作用，树木可能会从林线中消失。树分布的实际局部边缘，即已实现生态位的描绘，是由随机效应驱动的。因此，树线理论和假设检验不可避免地与基本的生态位概念联系在一起。