We test the relationship between canopy photosynthesis and reflected near‐infrared radiation from vegetation across a range of functional (photosynthetic pathway and capacity) and structural conditions (leaf area index, fraction of green and dead leaves, canopy height, reproductive stage, and leaf angle inclination), weather conditions, and years using a network of field sites from across central California. We based our analysis on direct measurements of canopy photosynthesis, with eddy covariance, and measurements of reflected near‐infrared and red radiation from vegetation, with light‐emitting diode sensors. And we interpreted the observed relationships between photosynthesis and reflected near‐infrared radiation using simulations based on the multilayer, biophysical model, CanVeg. Measurements of reflected near‐infrared radiation were highly correlated with measurements of canopy photosynthesis on half‐hourly, daily, seasonal, annual, and decadal time scales across the wide range of function and structure and weather conditions. Slopes of the regression between canopy photosynthesis and reflected near‐infrared radiation were greatest for the fertilized and irrigated C₄ corn crop, intermediate for the C₃ tules on nutrient‐rich organic soil and nitrogen fixing alfalfa, and least for the native annual grasslands and oak savanna on nutrient‐poor, mineral soils. Reflected near‐infrared radiation from vegetation has several advantages over other remotely sensed vegetation indices that are used to infer canopy photosynthesis; it does not saturate at high leaf area indices, it is insensitive to the presence of dead legacy vegetation, the sensors are inexpensive, and the reflectance signal is strong. Hence, information on reflected near‐infrared radiation from vegetation may have utility in monitoring carbon assimilation in carbon sequestration projects or on microsatellites orbiting Earth for precision agriculture applications.

中文翻译：

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植被在功能，结构，生理能力和天气的光谱范围内具有冠层光合作用的尺度上的近红外辐射

我们测试了冠层光合作用与植被在各种功能（光合途径和容量）和结构条件（叶面积指数，绿叶和枯叶的比例，冠层高度，生殖阶段和叶角）范围内反射的近红外辐射之间的关系。倾斜度），天气条件和年份（使用来自加利福尼亚州中部的现场站点网络）。我们的分析基于对冠层光合作用的直接测量（具有涡旋协方差），以及基于发光二极管传感器对植被反射的近红外和红色辐射的测量。我们使用基于多层生物物理模型CanVeg的模拟解释了光合作用与反射的近红外辐射之间的关系。在功能，结构和天气状况的广泛范围内，反射的近红外辐射的测量值与半小时，每日，季节性，年度和十年时间尺度上的冠层光合作用的测量值高度相关。施肥和灌溉的C冠层光合作用与反射近红外辐射之间的回归斜率最大。₄种玉米作物，在营养丰富的有机土壤和固氮紫花苜蓿中的碳₃郁金香中间产物，在营养贫乏的矿物土壤上最少的原生一年生草地和橡树大草原。来自植被的反射近红外辐射比用于推断冠层光合作用的其他遥感植被指数具有多个优势。它在高叶面积指数下不会饱和，对死去的遗留植被不敏感，传感器价格便宜，反射信号强。因此，有关植被反射的近红外辐射的信息可用于监测固碳项目中的碳同化，或用于精密农业应用的绕地球轨道运行的微卫星。