Fire regimes and forest composition in Canadian mixedwood boreal forest

景观结构及其与干扰制度的相互作用是理解北方森林镶嵌的关键因素。一些研究表明，频繁、大规模和严重的火灾可能会造成缺乏后期演替物种的林分，因为这些物种必须通过未烧毁地区的种子重新入侵。火灾的严重程度，通过其控制苗床的可用性和生产力，也可以影响火灾后的组成和演替发展。我的长期目标是了解火制度如何控制北方森林的森林组成和生态过程。在未来5年，我建议通过3个补充项目来实现这一目标。第一个项目旨在完成加拿大混合木北方森林长期火灾状况的重建。以前的作品包括魁北克和安大略部分地区的领土。本建议书将弥补与BC之间的差距。将利用火灾地图和档案以及航空照片（自1930年代以来）重建火灾周期，以描绘二十世纪发生的火灾。 将使用树木年代学测量的林分形成年份来估计源自较老火灾的森林比例。在第二个项目中，我将使用可比的白杨代表横跨加拿大东部到西部的横断面，以评估如何消防制度，在区域和景观水平，控制多样性和继承的立场。第三个项目将在白杨、云杉和冷杉丰富的北方东部进行。我将评估火灾的严重程度如何控制火灾后的森林组成和演替途径。严重程度较低的火灾将以云杉为主，有利于苔藓，不包括白杨和冷杉。拟议的研究介绍了一种新的时空方法来解释植被镶嵌在北方森林。预期结果将有助于了解气候变化对植被变化的影响，确定生态系统对气候和干扰制度造成的变化的抵抗力。

Landscape structure and its interactions with disturbance regimes are key elements to consider in understanding boreal forest mosaics. Several studies have demonstrated that frequent, large and severe fires may contribute to the creation of stands lacking late successional species as these species have to reinvade by seeds from unburnt areas. Fire severity, via its control of seed-bed availability and productivity, could also influence post-fire composition and successional development. My long term objective is to understand how fire regimes control forest composition and ecological processes in the boreal forest. In the next 5 years I propose to address this objective through 3 complementary projects. The first project aims to complete the reconstruction of long-term fire regimes in the Canadian mixedwood boreal forest. Previous works included territories in Quebec and in some parts of Ontario. This proposal will cover the gap to BC. Fire cycles will be reconstructed using time since fires maps and archives, and aerial photographs (since the 1930s) will be used to delineate fires that occurred during the twentieth century. The proportion of forests originating from older fires will be estimated using year of stand initiation as measured by dendrochronology. In a second project, I will use comparable aspen stands across a transect from eastern to western Canada to assess how fire regimes, acting at the regional and landscape level, control diversity and succession at the stand level. The third project will be undertaken in the eastern boreal where aspen, spruce and fir are abundant. I will assess how fire severity controls post fire forest composition and successionnal pathways. Low severity fires would be dominated by spruce and would favour mosses and exclude aspen and fir. The proposed research introduces a new spatio-temporal approach to interpreting vegetation mosaics in the boreal forest. Anticipated results will contribute towards understanding the effects of climate change on vegetation changes by determining ecosystem resistance to changes due to climate and disturbance regimes.