Droughts preceding tree mortality events have increased in duration and intensity, especially in dry biomes.

The thresholds of drought duration and intensity required to provoke pulses of tree mortality across Earth's biomes remain unclear. Using globally-extensive updated databases of drought-associated tree mortality, we report substantial diversity in the types of drought events that cause tree death in different forest types. Tree-killing droughts are longer, more intense and have higher completeness (proportion of extreme drought within long-lasting droughts) in dry versus wet biomes.

Satellite-based evidence of recent decline in global forest recovery rate from tree mortality events.

Climate-driven forest mortality events have been extensively observed in recent decades, prompting the question of how quickly these affected forests can recover their functionality following such events. Here we assessed forest recovery in vegetation greenness (normalized difference vegetation index) and canopy water content (normalized difference infrared index) for 1,699 well-documented forest mortality events across 1,600 sites worldwide. By analysing 158,427 Landsat surface reflectance images sampled from these sites, we provided a global assessment on the time required for impacted forests to return to their pre-mortality state (recovery time).

Spectral ecophysiology: hyperspectral pressure-volume curves to estimate leaf turgor loss.

Turgor loss point (TLP) is an important proxy for plant drought tolerance, species habitat suitability, and drought-induced plant mortality risk. Thus, TLP serves as a critical tool for evaluating climate change impacts on plants, making it imperative to develop high-throughput and in situ methods to measure TLP. We developed hyperspectral pressure-volume curves (PV curves) to estimate TLP using leaf spectral reflectance.

Climate-induced tree-mortality pulses are obscured by broad-scale and long-term greening.

Vegetation greening has been suggested to be a dominant trend over recent decades, but severe pulses of tree mortality in forests after droughts and heatwaves have also been extensively reported. These observations raise the question of to what extent the observed severe pulses of tree mortality induced by climate could affect overall vegetation greenness across spatial grains and temporal extents. To address this issue, here we analyse three satellite-based datasets of detrended growing-season normalized difference vegetation index (NDVI) with spatial resolutions ranging from 30 m to 8 km for 1,303 field-documented sites experiencing severe drought- or heat-induced tree-mortality events around the globe.

Evidence of combined flower thermal and drought vulnerabilities portends reproductive failure under hotter-drought conditions.

Despite the abundant evidence of impairments to plant performance and survival under hotter-drought conditions, little is known about the vulnerability of reproductive organs to climate extremes. Here, by conducting a comparative analysis between flowers and leaves, we investigated how variations in key morphophysiological traits related to carbon and water economics can explain the differential vulnerabilities to heat and drought among these functionally diverse organs. Due to their lower construction costs, despite having a higher water storage capacity, flowers were more prone to turgor loss (higher turgor loss point; Ψ) than leaves, thus evidencing a trade-off between carbon investment and drought tolerance in reproductive organs.

Hydraulic variability of tropical forests is largely independent of water availability.

Tropical rainforest woody plants have been thought to have uniformly low resistance to hydraulic failure and to function near the edge of their hydraulic safety margin (HSM), making these ecosystems vulnerable to drought; however, this may not be the case. Using data collected at 30 tropical forest sites for three key traits associated with drought tolerance, we show that site-level hydraulic diversity of leaf turgor loss point, resistance to embolism (P ), and HSMs is high across tropical forests and largely independent of water availability. Species with high HSMs (>1 MPa) and low P values (< -2 MPa) are common across the wet and dry tropics.

Rooting depth and xylem vulnerability are independent woody plant traits jointly selected by aridity, seasonality, and water table depth.

Evolutionary radiations of woody taxa within arid environments were made possible by multiple trait innovations including deep roots and embolism-resistant xylem, but little is known about how these traits have coevolved across the phylogeny of woody plants or how they jointly influence the distribution of species. We synthesized global trait and vegetation plot datasets to examine how rooting depth and xylem vulnerability across 188 woody plant species interact with aridity, precipitation seasonality, and water table depth to influence species occurrence probabilities across all biomes. Xylem resistance to embolism and rooting depth are independent woody plant traits that do not exhibit an interspecific trade-off.

Increased hydraulic risk in assemblages of woody plant species predicts spatial patterns of drought-induced mortality.

Predicting drought-induced mortality (DIM) of woody plants remains a key research challenge under climate change. Here, we integrate information on the edaphoclimatic niches, phylogeny and hydraulic traits of species to model the hydraulic risk of woody plants globally. We combine these models with species distribution records to estimate the hydraulic risk faced by local woody plant species assemblages.

Cholecystoappendiceal Fistula From Appendiceal Adenocarcinoma Requiring a Right Hemicolectomy With Cytoreduction and Hyperthermic Intraperitoneal Chemotherapy.

Bilioenteric fistulae are rare and difficult to manage complications of chronic cholecystitis. While cholecystoduodenal and cholecystocolic fistulae are more common, a cholecystoappendiceal fistula is an extremely rare finding. We report the presentation and operative management of a 59-year-old male with cholecystoappendiceal fistula and associated abscess in the gallbladder fossa.

Aridity-dependent sequence of water potentials for stomatal closure and hydraulic dysfunctions in woody plants.

The sequence of physiological events during drought strongly impacts plants' overall performance. Here, we synthesized the global data of stomatal and hydraulic traits in leaves and stems of 202 woody species to evaluate variations in the water potentials for key physiological events and their sequence along the climatic gradient. We found that the seasonal minimum water potential, turgor loss point, stomatal closure point, and leaf and stem xylem vulnerability to embolism were intercorrelated and decreased with aridity, indicating that water stress drives trait co-selection.

Global field observations of tree die-off reveal hotter-drought fingerprint for Earth's forests.

Earth's forests face grave challenges in the Anthropocene, including hotter droughts increasingly associated with widespread forest die-off events. But despite the vital importance of forests to global ecosystem services, their fates in a warming world remain highly uncertain. Lacking is quantitative determination of commonality in climate anomalies associated with pulses of tree mortality-from published, field-documented mortality events-required for understanding the role of extreme climate events in overall global tree die-off patterns.

Climate Change Risks to Global Forest Health: Emergence of Unexpected Events of Elevated Tree Mortality Worldwide.

Recent observations of elevated tree mortality following climate extremes, like heat and drought, raise concerns about climate change risks to global forest health. We currently lack both sufficient data and understanding to identify whether these observations represent a global trend toward increasing tree mortality. Here, we document events of sudden and unexpected elevated tree mortality following heat and drought events in ecosystems that previously were considered tolerant or not at risk of exposure.

A thin line between life and death: Radial sap flux failure signals trajectory to tree mortality.

This article comments on: Seeking the "point of no return" in the sequence of events leading to mortality of mature trees.

Picture worth a thousand words: Updating repeat photography for 21st century ecologists.

Anthropogenic climate change is altering every ecosystem on Earth. Understanding these changes requires quality baseline measurements of ecosystem states. While satellite imagery provides a coarse baseline for regional-scale changes in vegetation, landscape-scale observations are lacking.