DYNAMICS OF THUJA-OCCIDENTALIS IN AN AGRICULTURAL LANDSCAPE OF SOUTHERN QUEBEC
DYNAMICS OF THUJA-OCCIDENTALIS IN AN AGRICULTURAL LANDSCAPE OF SOUTHERN QUEBEC
复制标题
DOI：
10.2307/3236352
复制
发表时间：
1995-09-01
影响因子：
2.8
通讯作者：
BOUCHARD, A
中科院分区：
文献类型：
--
作者：
DEBLOIS, S;BOUCHARD, A
人类影响的植物分布格局和主导干扰动态的农业景观上圣罗兰，魁北克。我们调查的影响，这种影响的动态崖柏在南部魁北克的阔叶林。该种为双峰型，既可生长于干燥生境，也可生长于湿润生境。在研究区域，虽然被普遍认为是一个很差的竞争者，但它仍然以密集的种群存在，似乎抵制了更耐受的物种的入侵。由于糖槭在中温条件下可能是演替后期的优势种，我们首先评估了非生物和历史因素在34 T分布中的相对重要性。occupientalis和21 A.甘蔗站。然后，我们分类55个立场，包括T。对13个混合生境中的种与近缘种之间的动态关系进行了研究。occi dentalis和A.甘蔗林表明，土地利用和排水是与植物群落组成相关的最重要的变量。以排水量为约束变量的部分CCA显示T. octagentalis林分显着相关，现在或过去的使用作为牧场。对55个林分进行了对应分析，其中T. octagentalis是目前产生了一个明显的隔离近单种林分和混合社区，但所选择的环境变量在解释植被梯度在这个尺度上并不显着。在所有混交林中，崖柏与美洲榆、红槭、杨桦、美洲白蜡、白桦、白saccharum和南方铁杉Tsuga candeilsis。最后，13个中位混交林分的径级排序没有表现出a向A的收敛。我们的研究结果表明，放牧在T.而竞争过程和景观格局可能有助于维持相对持久的T.在风景中屹立不倒。
Human impact influences patterns of plant distribution and dominates disturbance dynamics in the agricultural landscape of Haut-Saint-Laurent, Quebec. We investigated the influence of such impact on the dynamics of Thuja occidentalis in the hardwood forest of southern Quebec. A bimodal species of either dry or wet habitats, T. occidentalis has successfully invaded mesic sites of the study area where, although generally considered a poor competitor, it persists as dense populations that seem to resist invasion by more tolerant species. As Acer saccharum is expected to be a dominant late-successional species under mesic conditions, we first evaluated the relative importance of abiotic and historical factors in the distribution of 34 T. occidentalis stands and 21 A. saccharum stands. We then classified 55 stands that include T. occidentalis and investigated the dynamic relationships between the species and its associates in 13 mixed mesic sites.Canonical correspondence analysis (CCA) of T. occi dentalis and A. saccharum stands suggested that land use and drainage are the most important variables correlated with plant community composition. A partial CCA with drainage as the constraining variable showed that T. occidentalis stands were significantly associated to present or past use as pasture. Correspondence analysis of 55 stands where T. occidentalis is present produced a clear segregation between nearly mono-specific stands and mixed communities, but the chosen environmental variables were not significant in explaining the vegetation gradient at this scale. In all mixed stands, Thuja a occidentalis was most often associated with Ulmus americana, Acer rubrum, Betula populifolia, Fraxinus americana, A. saccharum, and Tsuga canndeilsis. Finally, size-class ordination of 13 mixed mesic stands did not show convergence a toward A. saccharum.Our results suggest that grazing has played a significant part in the appearance of T. occidentalis stands on mesic sites, whereas competition processes and landscape patterns possibly contribute to the maintenance of relatively persistent T. occidentalis stands in the landscape.