REMOTE SENSING OF BIOPHYSICAL VARIABLES AT MULTIPLE SPATIAL SCALES ALONG A LATITUDINAL GRADIENT IN THE CANADIAN ARCTIC

加拿大北极沿纬度梯度多空间尺度生物物理变量的遥感

• 批准号: RGPIN-2014-03822
• 负责人: Treitz, Paul
• 金额: $ 2.7万
• 依托单位: Queen's University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=633956
• 关键词: REMOTE; SENSING; BIOPHYSICAL; VARIABLES; MULTIPLE

Tundra ecosystems account for a large proportion of Canada’s land surface and are important systems within the context of environmental change research. Tundra ecosystems are thought to be particularly sensitive to changes in climate, yet it remains unclear as to how they will respond. Changes in tundra ecosystem patterns and processes will be expressed through shifts in vegetation phenology and species composition and abundance. In addition to the obvious impacts of increasing air temperatures, there are a number of factors that serve as controls on vegetation growth in the Canadian Arctic, including soil moisture, nutrient availability, soil type and topography/micro-topography, some of which are also impacted by warming temperatures. Hence, high spatial resolution remote sensing provides an opportunity to estimate and monitor vegetation variability, with the potential to quantify biophysical variables that control carbon fluxes over large areas. However, detailed in situ studies are required for calibration and validation of appropriate remote sensing models to estimate these variables.The focus of my NSERC Discovery Grant will be on modeling biophysical variables at multiple scales along a latitudinal gradient (~64°-75°N) for the Canadian Arctic; providing a mean-July temperature gradient of approximately 10°C. This research will be conducted at Sabine Peninsula (77ºN) and Cape Bounty (75ºN), Melville Island; Boothia Peninsula (71ºN); and Apex River, Baffin Island (64ºN), Nunavut. Although there have been studies examining biophysical variables at these latitudes, they have largely been limited to broad spatial scales (i.e., 1-8 km2) with limited field support. There has been very little research conducted in Canada's North on relating biophysical variables to high spatial resolution remote sensing data (<10 m); nor how these variables are linked to ecosystem processes (e.g., carbon flux/net ecosystem exchange). My research will: (i) quantify the relationships between biophysical variables and spectral reflectance at high spatial resolutions; (ii) model the relationships between biophysical variables and ecosystem processes; and (iii) model biophysical variables, including carbon exchange, at multiple scales in order to project changes in these variables over space and time.Variables of significance for productivity modeling and estimating net ecosystem exchange include above-ground phytomass, percent vegetation cover and fraction of absorbed photosynthetically active radiation. These are critical structural and physiological variables linked to many ecosystem processes (e.g., phytomass plays a significant role in assessing carbon stocks, is an important element in global change and productivity models, and is a measure of vegetation community structure which influences biodiversity). These variables will be measured using direct measurement and photo-plot techniques employing near-infrared photography and spectral indices. In order to scale up variables, models will be developed between field measurements and photo-plot data for comparison to high (WorldView-2), intermediate (Landsat 8) and coarse (MODIS) resolution remote sensing data. With the results of this research, i.e., modeling of biophysical variables and ecosystem processes at multiple scales, we will be able to make knowledgeable policy decisions related to development in the North. In addition, this research will help us develop adaptation strategies for communities and resource industries living and operating in Canada’s North. Finally, training of undergraduate and graduate students will contribute to the next generation of Arctic scientists, specifically earth and environmental scientists trained in arctic field methods and remote sensing image processing.

苔原生态系统占加拿大陆地面积的很大比例，是环境变化研究中的重要系统。冻土带生态系统被认为对气候变化特别敏感，但它们将如何应对尚不清楚。冻土带生态系统格局和过程的变化将通过植被物候、物种组成和丰度的变化来表达。除了气温升高的明显影响外，还有许多因素对加拿大北极地区的植被生长起着控制作用，包括土壤湿度、养分有效性、土壤类型和地形/微地形，其中一些因素也受到温度升高的影响。因此，高空间分辨率遥感提供了估计和监测植被变化的机会，并有可能量化控制大面积碳通量的生物物理变量。但是，需要进行详细的实地研究，以便校准和验证适当的遥感模型，以估计这些变量。我的NSERC发现基金的重点将是在加拿大北极沿纬度梯度（~64°-75°N）的多个尺度上模拟生物物理变量；七月平均温度梯度约为10°C。这项研究将在萨宾半岛（77ºN）和邦蒂角（75ºN），梅尔维尔岛进行；布西亚半岛（北纬71度）；和阿佩克斯河，巴芬岛（北纬64度），努纳武特。虽然对这些纬度的生物物理变量进行了研究，但这些研究大多局限于较宽的空间尺度（即1-8平方公里），实地支持有限。在加拿大北部，很少进行将生物物理变量与高空间分辨率遥感数据（<10米）联系起来的研究；也没有说明这些变量如何与生态系统过程联系起来（例如，碳通量/生态系统净交换）。我的研究将：(i)量化高空间分辨率下生物物理变量与光谱反射率之间的关系；模拟生物物理变量与生态系统过程之间的关系；（iii）在多个尺度上模拟生物物理变量，包括碳交换，以便预测这些变量随时间和空间的变化。对生产力建模和估算净生态系统交换有重要意义的变量包括地上生物量、植被覆盖度百分比和吸收光合有效辐射的比例。这些是与许多生态系统过程相关的关键结构和生理变量（例如，植物质量在评估碳储量方面起着重要作用，是全球变化和生产力模型的一个重要因素，是影响生物多样性的植被群落结构的量度）。这些变量将使用直接测量和采用近红外摄影和光谱指数的照片图技术进行测量。为了扩大变量的比例，将在实地测量和照片图数据之间开发模型，以便与高分辨率（WorldView-2）、中分辨率（Landsat 8）和粗分辨率（MODIS）遥感数据进行比较。根据这项研究的结果，即在多个尺度上对生物物理变量和生态系统过程进行建模，我们将能够做出与北方发展相关的明智政策决策。此外，这项研究将有助于我们为在加拿大北部生活和经营的社区和资源行业制定适应策略。最后，对本科生和研究生的培训将有助于培养下一代北极科学家，特别是在北极实地方法和遥感图像处理方面受过训练的地球和环境科学家。