Comprehensive Quantification of the Responses of Ecosystem Production and Respiration to Drought Time Scale, Intensity and Timing in Humid Environments: A FLUXNET Synthesis. Issue 5 (6th May 2022)

• Record Type: Journal Article
• Authors: Jiao, Wenzhe; Wang, Lixin; Wang, Honglang; Lanning, Matthew; Chang, Qing; Novick, Kimberly A.
• Is Part Of: Journal of geophysical research. Volume 127:Issue 5(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-05-06
• Subjects: ecohydrology -- climate change -- drought -- FLUXNET -- SPEI; Geobiology -- Periodicals; Biogeochemistry -- Periodicals; Biotic communities -- Periodicals; Geophysics -- Periodicals; 577.14
• DOI: 10.1029/2021JG006431
• Languages: English
• ISSNs: 2169-8953

Abstract

Abstract: Drought is one of the most important natural hazards impacting ecosystem carbon cycles. However, it is challenging to quantify the impacts of drought on ecosystem carbon balance and several factors hinder our explicit understanding of the complex drought impacts. First, drought impacts can have different time dimensions such as simultaneous, cumulative, and lagged impacts on ecosystem carbon balance. Second, drought is not only a multiscale (e.g., temporal and spatial) but also a multidimensional (e.g., intensity, time‐scale, and timing) phenomenon, and ecosystem production and respiration may respond to each drought dimension differently. In this study, we conducted a comprehensive drought impact assessment on ecosystem productivity and respiration in humid regions by including different drought dimensions using global FLUXNET observations. Short‐term drought (e.g., 1‐month drought) generally did not induce a decrease in plant productivity even under high severity drought. However, ecosystem production and respiration significantly decreased as drought intensity increased for droughts longer than 1 month in duration. Drought timing was important, and ecosystem productivity was most vulnerable when drought occurred during or shortly after the peak vegetation growth. We found that lagged drought impacts more significantly affected ecosystem carbon uptake than simultaneous drought, and that ecosystem respiration was less sensitive to drought time scale than ecosystem production. Overall, our results indicated that temporally‐standardized meteorological drought indices can be used to reflect plant productivity decline, but drought timing, antecedent, and cumulative drought conditions need to be considered together. Plain Language Summary: Drought has not only simultaneous impacts but also cumulative and lagged impacts on ecosystem carbon cycles. In addition, different drought intensity, time‐scale, and timing may impact ecosystem production and respiration differently. Those multiple dimensions of drought have made the accurate drought impact assessments on ecosystem carbon cycles challenging. Our study provided a comprehensive quantification of various drought dimensions on ecosystem production and respiration using global flux tower observations and multiple time scales of one widely used drought index. Our results indicated that drought timing, lagged impacts, and long‐term drought intensity are the most significant drought dimensions impacting ecosystem carbon uptake. We found that while most earlier drought studies focus on the impacts of simultaneous drought, the lagged drought impacts are more significantly impacting ecosystem carbon uptake. Ecosystem respiration and production showed different sensitivity to drought cumulative impacts. Drought has the greatest effect on vegetation during and shortly after the peak of the growing season. These results help us to reconsider the impacts of drought on ecosystem carbon uptake by incorporating all the significant factors to provide a more accurate estimation and prediction of drought impacts. Key Points: Lagged drought impacts are more significantly impacting ecosystem carbon uptake than simultaneous drought impacts Short‐term drought generally does not induce plant productivity decrease in humid regions Ecosystem productivity is most sensitive to drought that occurs shortly after the peak stage of the growing season