Abstract: Texas experienced the worst drought in its 100-year history in 2011, resulting in the death of approximately 300 million trees. The high number of sudden deaths had a significant impact on forest ecosystems. This study aimed to gain insight into the long-term and combined impacts of drought-induced forest tree deaths and their effects on biomass. This study used data obtained from 1797 National Forest Inventory (NFI) plots to analyze trends and major causes of changes in tree biomass at the sample plot level in East Texas forests over the past 20 years (2000 − 2019). In this study, forest trees in East Texas were divided into diameter at breast height (dbh), height, stand types, latitude, elevation, ecological zones, and FIA Unit. Principal component analysis (PCA) was also performed using drought intensity, drought duration, the four competing factor indicators, and the biomass loss rate of forest trees to better understand r drought impacts on forest trees. The results showed the lowest biomass loss rate of Pine species. Similarly, trees with shorter height and smaller dbh experienced a higher biomass loss rate. A higher biomass loss rate was observed in natural forests, West Gulf Coastal Plain and Plain and Southern East Texas ecoregion experienced higher biomass loss. Principal component analyses of drought intensity, drought duration, and the four competing metrics revealed that overall drought was the main contributor to biomass loss rates, and that drought intensity and drought duration had comparable effects on biomass loss rates.

Key words: Drought intensity, Drought length, Climate extremes, Biomass · Texas