Skálová Hana, Moravcová Lenka, Dixon Anthony F G, Kindlmann P, Pyšek Petr
Department of Invasion Ecology, Institute of Botany, The Czech Academy of Sciences, CZ-252 43, Průhonice, Czech Republic
Department of Invasion Ecology, Institute of Botany, The Czech Academy of Sciences, CZ-252 43, Průhonice, Czech Republic.
AoB Plants. 2015 Apr 28;7:plv044. doi: 10.1093/aobpla/plv044.
Plant species distributions are determined by the response of populations to regional climates; however, little is known about how alien plants that arrive in central Europe from climatically warmer regions cope with the temperature conditions at the early stage of population development. Ambrosia artemisiifolia (common ragweed) is an invasive annual plant causing considerable health and economic problems in Europe. Although climate-based models predict that the whole of the Czech Republic is climatically suitable for this species, it is confined to the warmest regions. To determine the factors possibly responsible for its restricted occurrence, we investigated the effects of temperature and nutrient availability on its seedlings. The plants were cultivated at one of seven temperature regimes ranging from 10 to 34 °C, combined with three nutrient levels. The data on the rate of leaf development were used to calculate the lower developmental threshold (LDT, the temperature, in °C, below which development ceases), the sum of effective temperatures (SET, the amount of heat needed to complete a developmental stage measured in degree days above LDT) and width of the thermal window. The rate of development decreased with decrease in temperature and nutrient supply. Besides this, the decrease in the availability of nutrients resulted in decreased LDT, increased SET and wider thermal window. The dependence of LDT and SET on the availability of nutrients contradicts the concept that thermal constants do not vary. Our results highlight temperature as the main determinant of common ragweed's distribution and identify nutrient availability as a factor that results in the realized niche being smaller than the fundamental niche; both of these need to be taken into account when predicting the future spread of A. artemisiifolia.
植物物种分布由种群对区域气候的响应决定；然而，对于从气候较温暖地区抵达中欧的外来植物在种群发展早期如何应对温度条件，我们却知之甚少。豚草是一种入侵性一年生植物，在欧洲造成了相当严重的健康和经济问题。尽管基于气候的模型预测整个捷克共和国在气候上都适合该物种生长，但它却局限于最温暖的地区。为了确定可能导致其分布受限的因素，我们研究了温度和养分有效性对其幼苗的影响。这些植物在10至34°C的七种温度 regime 之一与三种养分水平相结合的条件下进行培育。关于叶片发育速率的数据被用于计算较低发育阈值（LDT，低于该温度发育停止的温度，单位为°C）、有效温度总和（SET，完成一个发育阶段所需的热量，以高于LDT的度日数衡量）以及热窗口宽度。发育速率随着温度和养分供应的降低而下降。除此之外，养分有效性的降低导致LDT降低、SET增加以及热窗口变宽。LDT和SET对养分有效性的依赖性与热常数不变的概念相矛盾。我们的研究结果突出了温度是豚草分布的主要决定因素，并确定养分有效性是导致实际生态位小于基础生态位的一个因素；在预测豚草未来的扩散时，这两个因素都需要被考虑在内。
