Department of Plant Physiology and Plant Ecology, Agronomy Institute, Hungarian University for Life and Agriculture, 2100 Gödöllő, Páter 1., Hungary; HUN-REN-MATE Agroecology Research Group, 2100 Gödöllő, Páter 1., Hungary.
Department of Plant Physiology and Plant Ecology, Agronomy Institute, Hungarian University for Life and Agriculture, 2100 Gödöllő, Páter 1., Hungary.
Sci Total Environ. 2024 Jan 10;907:168053. doi: 10.1016/j.scitotenv.2023.168053. Epub 2023 Oct 26.
Drought stress occurrence and recovery from drought can be detected using a single spatial set of simultaneous observations of SIF and canopy temperature records. Temporal and spatial responses to drought and heat stresses by plant stands of a drought-adapted diverse grassland ecosystem were studied using sun induced fluorescence (SIF,OA and OB bands) and further ecophysiological (canopy temperature (Tsurf), spatially modeled evapotranspiration, vegetation reflectance spectra) variables collected along spatial sampling grids while also utilizing eddy covariance measured carbon dioxide (net ecosystem exchange: NEE, gross primary production: GPP) and water flux (evapotranspiration: ET) data. The grids were of 0.5 and 5 ha spatial extents and contained 78 sampling points. Data were collected in four spatial sampling campaigns, two under drought (early summer) and another two during and after recovery (midsummer) at both spatial resolutions. Small values of spatial SIF_A averages (around 0.5 mW m nm sr) under strong early summer drought increased (to around 2 mW m nm sr) due recovery upon rain arrivals, showing high (R: 0.8-0.88) positive temporal correlations to eddy covariance measured carbon (GPP, NEE) and water (ET) fluxes. Spatial averages of LAI, vegetation indices (NDVI, NIRv) and modeled ET followed similar temporal patterns. While SIF was depressed by drought, it showed higher values in high canopy temperature vegetation patches than in vegetation patches with lower Tsurf. The spatial pattern of higher SIF in higher Tsurf patches was persistent (2 weeks) under drought. The positive SIF_A-Tsurf spatial correlation turned into negative/not significant after recovery of the grassland from the drought, while hot summer weather persisted. It is proposed that, by using a single set of simultaneously measured spatial SIF and Tsurf data it is possible to infer whether the studied vegetation is under drought (and heat) stress while it could not be decided on the base of SIF data alone. Evaluation of the slope of the above relationship seems therefore beneficial before e.g. starting the (stress) classification procedure based on SIF.
可以使用单一空间的同时观测到的 SIF 和冠层温度记录来检测干旱胁迫的发生和干旱的恢复。通过对适应干旱的多样化草原生态系统的植物群落进行太阳诱导荧光（SIF，OA 和 OB 波段）和进一步的生理生态（冠层温度（Tsurf），空间建模的蒸散，植被反射光谱）变量的研究，利用沿空间采样网格收集的时空响应来研究干旱和热胁迫，同时还利用涡度协方差测量的二氧化碳（净生态系统交换：NEE，总初级生产力：GPP）和水通量（蒸散：ET）数据。这些网格的空间范围为 0.5 和 5 公顷，包含 78 个采样点。在四个空间采样活动中收集了数据，其中两个在干旱（初夏）期间进行，另外两个在两个期间进行和恢复（仲夏）在这两种空间分辨率下进行。在强烈的初夏干旱下，空间 SIF_A 平均值的较小值（约 0.5 mW m nm sr）由于降雨到达后的恢复而增加（约 2 mW m nm sr），与涡度协方差测量的碳（GPP，NEE）和水（ET）通量具有很高的正时间相关性（R：0.8-0.88）。LAI，植被指数（NDVI，NIRv）和模型化 ET 的空间平均值遵循相似的时间模式。虽然 SIF 受到干旱的抑制，但它在冠层温度较高的植被斑块中显示出比 Tsurf 较低的植被斑块更高的值。在干旱条件下，Tsurf 较高的 SIF 空间模式持续（2 周）。在草原从干旱中恢复后，SIF_A-Tsurf 空间相关性变为负/不显著，而炎热的夏季天气仍在持续。因此，提出通过使用一组同时测量的空间 SIF 和 Tsurf 数据，可以推断出所研究的植被是否处于干旱（和热）胁迫之下，而不能仅基于 SIF 数据做出决定。在基于 SIF 开始（胁迫）分类程序之前，评估上述关系的斜率似乎是有益的。
