Canopy temperature dynamics are closely aligned with ecosystem water availability across a water- to energy-limited gradient

IF 5.6 1区农林科学 Q1 AGRONOMY Agricultural and Forest Meteorology Pub Date : 2024-08-28 DOI:10.1016/j.agrformet.2024.110206

Mostafa Javadian , Russell L. Scott , William Woodgate , Andrew D. Richardson , Matthew P. Dannenberg , William K. Smith

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引用次数: 0

Abstract

Canopy temperature (T_c) plays an important role in regulating the rates of mass and energy fluxes at the leaf surface. Better understanding of the relationship between T_c and water availability may enable more accurate monitoring of ecosystem functioning in a changing climate. Here, we used high spatiotemporal resolution thermal infrared cameras deployed at three eddy covariance flux tower sites along a water- to energy-limited gradient – including a predominately water-limited grassland/shrubland site, a seasonally water-limited evergreen needleleaf forest, and a predominantly energy-limited deciduous broadleaf forest – to determine T_c seasonality and its relationship with gross primary productivity (GPP) and environmental drivers. We found midday T_c was generally warmer than air temperature (T_air) during the growing season (T_c:T_air slope: 1.14–1.27) for all sites. Water-limited sites exhibited higher positive T_c deviations from T_air (2.30 ± 0.06 °C) compared to the energy-limited site (1.29 ± 0.09 °C) partly due to their reduced latent heat fluxes during water-limited periods. We further found that the T_c:T_air slope increased with site aridity, namely for 1.14 slope for the grassland, 1.15 for the evergreen forest, and 1.27 for the broadleaf forest. Peak GPP occurred when T_c was higher than T_air across all sites, with peak GPP at the grassland site occurring at +1.1 °C (T_c-T_air) and peak GPP at the broadleaf evergreen site occurring at +2.2 °C (T_c-T_air). T_c-T_air dynamics were mostly associated with soil water content at water-limited sites where canopies undergo a substantial cooling during the transition from dormancy to the peak GPP, while net radiation played a crucial role at the energy-limited site where the canopy heats up compared to T_air over the same phenological transition. Our findings provide novel insights into T_c-ecosystem water availability links, highlighting the drivers of T_c-T_air across diverse ecosystems in various phenological stages, which has implications for ecosystem management in a changing climate.

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树冠温度动态与生态系统从水到能量限制梯度的水供应密切相关

树冠温度（Tc）在调节叶面的质量和能量通量速率方面发挥着重要作用。更好地了解树冠温度与水分供应之间的关系，可以更准确地监测气候变化下的生态系统功能。在这里，我们使用了高时空分辨率热红外热像仪，部署在沿水分到能量限制梯度的三个涡度协方差通量塔站点，包括一个主要受水分限制的草地/灌木丛站点、一个受季节性水分限制的常绿针叶林站点和一个主要受能量限制的落叶阔叶林站点，以确定 Tc 的季节性及其与总初级生产力（GPP）和环境驱动因素的关系。我们发现，在生长季节，所有地点的正午温度（Tc）普遍高于空气温度（Tair）（Tc:Tair 斜率：1.14-1.27）。与能量受限的地点（1.29 ± 0.09 °C）相比，水分受限的地点表现出更高的 Tc 与 Tair 的正偏差（2.30 ± 0.06 °C），部分原因是水分受限期间潜热通量减少。我们还发现，Tc：Tair 的斜率随地点的干旱程度而增加，草地为 1.14，常绿林为 1.15，阔叶林为 1.27。所有地点的 GPP 峰值都出现在 Tc 高于 Tair 时，草原地点的 GPP 峰值出现在 +1.1 °C（Tc-Tair），常绿阔叶林地点的 GPP 峰值出现在 +2.2 °C（Tc-Tair）。Tc-Tair的动态变化主要与限水地点的土壤含水量有关，在这些地点，树冠在从休眠期向GPP峰值过渡的过程中大幅降温，而在限能地点，净辐射起着关键作用，在相同的物候过渡期间，树冠比Tair升温。我们的研究结果为 Tc 与生态系统水供应的联系提供了新的见解，突出了不同生态系统在不同物候期的 Tc-Tair 驱动因素，这对气候变化下的生态系统管理具有重要意义。

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来源期刊

Agricultural and Forest Meteorology 农林科学-林学

CiteScore

10.30

自引率

9.70%

发文量

415

审稿时长

69 days

期刊介绍： Agricultural and Forest Meteorology is an international journal for the publication of original articles and reviews on the inter-relationship between meteorology, agriculture, forestry, and natural ecosystems. Emphasis is on basic and applied scientific research relevant to practical problems in the field of plant and soil sciences, ecology and biogeochemistry as affected by weather as well as climate variability and change. Theoretical models should be tested against experimental data. Articles must appeal to an international audience. Special issues devoted to single topics are also published. Typical topics include canopy micrometeorology (e.g. canopy radiation transfer, turbulence near the ground, evapotranspiration, energy balance, fluxes of trace gases), micrometeorological instrumentation (e.g., sensors for trace gases, flux measurement instruments, radiation measurement techniques), aerobiology (e.g. the dispersion of pollen, spores, insects and pesticides), biometeorology (e.g. the effect of weather and climate on plant distribution, crop yield, water-use efficiency, and plant phenology), forest-fire/weather interactions, and feedbacks from vegetation to weather and the climate system.