quantifying the spatial impact of exotic plant invasion on ecosystem functioning-from the leaf to the landscape level

外来入侵物种是对地球生物多样性的一个主要威胁，因为它们大大改变了生态系统的生物地球化学循环，对生态系统的功能产生重大影响。然而，迄今为止，明确量化这些影响仍然具有挑战性。原因之一是缺乏足够的方法来捕捉与生物入侵相关的生态系统变化的空间维度。传统的生理生态学方法在很大程度上局限于比较邻近的植物个体，往往忽略了空间维度。景观生态学虽然在较大的空间尺度上运作，但通常仅限于测量生物体水平以上的模式和过程，例如物种分布和传播速度。本项目的中心目标是将生态生理学与景观生态学联系起来，从而对植物入侵的空间方面进行综合理解，从而能够量化外来物种在空间尺度上的影响。高光谱遥感是一种非常适合于解决这一问题的技术，它允许使用光谱测量在叶片水平上量化本地物种生物化学的变化，同时允许使用航空图像放大到景观水平。我们将开发新的方法来量化植物入侵后生态系统功能的变化，从叶片到景观尺度，通过：（1）在叶片水平上校准生理和生化叶片特性和叶片13 C和15 N稳定同位素特征的光谱特征;（2）评估A.（3）利用光谱法研究了长叶相思在林分水平上的分布。longifolia和优势原生植被类型的景观尺度上使用高光谱航空图像。最后（4），我们将综合我们的研究结果在一个预测模型，这将使我们能够评估入侵物种对本地物种生理和生态系统功能的影响在景观尺度上。该项目建立在一个广泛的数据集，包括高光谱航空图像和激光雷达数据从EUFAR飞行活动在研究现场在2011年。此外，对入侵的A. longifolia和原生地中海植被是从超过10年的前期研究。我们的跨学科的方法将带来科学显着进一步评估入侵物种的影响的空间维度和量化生态系统功能的变化。此外，通过将景观生态学和生态生理学联系起来，该项目与入侵生物学之外的植物生态学高度相关，并将大大丰富我们对生态研究中空间尺度的重要性的理解。

Exotic invasive species represent a major threat to earths biodiversity, since they substantially alter biogeochemical cycles of ecosystems with large impacts on ecosystem functioning. However, to date, explicitly quantifying such impacts remains challenging. One reason is the lack of adequate methodology to capture the spatial dimension of ecosystem changes associated with biological invasion. Conventional ecophysiological approaches are largely restricted to comparing neighbouring plant individuals and tend to neglect the spatial dimension. Landscape ecology, although operating on larger spatial scales, is typically limited to measurements of patterns and processes above the organism level, such as species distribution and propagation speed.The central aim of this project is to link ecophysiology with landscape ecology, thus moving towards an integrated understanding of the spatial aspect of plant invasions, enabling the quantification of exotic species impacts across spatial scales. A highly suitable technology to address this purpose is hyperspectral remote sensing, which allows for quantifying alterations in native species biochemistry on the leaf level using spectral measurements while allowing to scale up to the landscape level using aerial images.Utilizing the case study of the N2-fixing leguminous tree Acacia longifolia, a problematic invader in coastal regions of Portugal and many ecosystems worldwide, we will develop new methodology for quantifying changes in ecosystem functioning after plant invasion from the leaf to the landscape scale, by: (1) calibrating physiological and biochemical leaf properties and foliar 13C and 15N stable isotopic signatures with spectral characteristics at the leaf level; (2) assessing the threshold of impact of A. longifolia in the surrounding vegetation at the stand-level using spectral methods; and (3) mapping the distribution of A. longifolia and dominant native vegetation types on the landscape scale using hyperspectral aerial images. Finally (4), we will synthesize our findings in a predictive model which will enable us to assess the impact of an invasive species on native species physiology and on ecosystem functioning at the landscape scale.This project builds on an extensive data set including hyperspectral aerial images and LiDAR data from a EUFAR flight campaign at the study site in 2011. Moreover, extensive knowledge on the invasive A. longifolia and native Mediterranean vegetation is available from over 10 years of prior research.Our interdisciplinary approach will bring science significantly further in evaluating the spatial dimension of invasive species impacts and in quantifying changes in ecosystem functioning. Furthermore, by linking landscape ecology and ecophysiology, this project is highly relevant for plant ecology beyond invasion biology and will significantly enrich our understanding of the significance of accounting for spatial scales in ecological studies.