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Introduction: Large-scale investments in restoring California’s forested watersheds are imperative for conserving biodiversity, enhancing water quality, and mitigating the future impacts of climate change. This study explores the underlying incentives, major challenges, and potential strategies associated with such investments. Methods: An online survey was administered to 43 experts in the field to gather their insights on forest watershed restoration investments. The collected responses were then analyzed using a combination of confirmatory factor analysis and regression analysis to elucidate patterns and relationships. Results: The analysis revealed that key environmental outcomes, such as reducing wildfire risks and protecting water supplies, are the principal motivators driving investment. At the same time, significant barriers emerged, including high costs, limited workforce capacity, and insufficient trust among stakeholders. The study also identified a series of effective strategies to overcome these obstacles, such as repositioning forest restoration as an infrastructure investment and clearly demonstrating its ecological, social, and economic benefits. Discussion: Overall, the findings underscore the need for more flexible funding frameworks, enhanced stakeholder engagement, and improved data infrastructures. By addressing these elements, policymakers and practitioners can pave the way for more resilient and sustainable forested-watershed ecosystems in California. 

Recent drought, wildfires and rising temperatures in the western US highlight the urgency of increasing resiliency in overstocked forests. However, limited valuation information hinders the broader participation of beneficiaries in forest management. We assessed how historical disturbances in California's Central Sierra Nevada affected live biomass, forest water use and carbon uptake and estimated marginal values of these changes. On average, low‐severity wildfire caused greater declines in forest evapotranspiration (ET), gross primary productivity (GPP) and live biomass than did commercial thinning. Low‐severity wildfires represent proxies for prescribed burns and both function as biomass removal to alleviate overstocked conditions. Increases in potential runoff over 15 years post‐disturbance were valued at $108,000/km²for commercial thinning versus $234,000/km²for low‐severity wildfire, based on historical water prices. Respective declines in GPP were valued at −$305,000 and −$1,317,000/km², based on an average social cost of carbon. Considering biomass levels created by commercial thinning and low‐severity fire as more‐sustainable management baselines for overstocked forests, carbon uptake over 15 years post‐disturbance can be viewed as a benefit rather than loss. Realizing this benefit upon management re‐entry may require sequestering thinned material. High‐severity wildfire and clearcutting resulted in greater declines in ET and thus greater potential water benefits but also substantial declines in GPP and live carbon. These lessons from historical disturbances indicate what benefit ranges from fuels treatments can be expected from more‐sustainable management of mixed‐conifer forests and the importance of setting an appropriate baseline. 

The social impacts of natural resource management are challenging to evaluate because their perceived benefits and costs vary across stakeholder groups. Nevertheless, ensuring social acceptance is essential to building public support for adaptive measures required for the sustainable management of ecosystems in a warming climate. Based on surveys with both members of the public and natural-resource professionals in California, we applied structural-equation modeling to examine how psychological factors impact individuals' attitudes toward management's capacity to reduce the impacts of disturbance events, including wildfires, smoke from wildfires, drought, water shortages, tree mortality, and utility failure. We found the members of the public more optimistic than natural-resource professionals, perceiving management capacity to be on average 3.04 points higher (of 10) and displaying higher levels of trust of the government on both the state (Δ = 11%) and federal levels (Δ = 19%). Personal experience with natural-resource events had a positive effect on perceived management in both the public (1.26) and the professional samples (5.05), whereas perceived future risk had a negative effect within both samples (professional = −0.91, public = −0.45). In addition, higher trust and perceived management effectiveness were also linked with higher perceptions of management capacity in the public sample (1.81 versus 1.24), which could affect the acceptance of management actions. Continued social acceptance in a period of increasing risk may depend on managers sharing personal experiences and risk perception when communicating with the public. The contemporary shift toward multibenefit aims is an important part of that message. 

Abstract Increasing drought frequency and severity in a warming climate threaten forest ecosystems with widespread tree deaths. Canopy structure is important in regulating tree mortality during drought, but how it functions remains controversial. Here, we show that the interplay between tree size and forest structure explains drought-induced tree mortality during the 2012-2016 California drought. Through an analysis of over one million trees, we find that tree mortality rate follows a “negative-positive-negative” piecewise relationship with tree height, and maintains a consistent negative relationship with neighborhood canopy structure (a measure of tree competition). Trees overshadowed by tall neighboring trees experienced lower mortality, likely due to reduced exposure to solar radiation load and lower water demand from evapotranspiration. Our findings demonstrate the significance of neighborhood canopy structure in influencing tree mortality and suggest that re-establishing heterogeneity in canopy structure could improve drought resiliency. Our study also indicates the potential of advances in remote-sensing technologies for silvicultural design, supporting the transition to multi-benefit forest management. 

After 4.5 billion years as an evolving and dynamic planet, the Earth continues to evolve but with human‐altered dynamics. Earth scientists have special opportunities and responsibilities to accelerate our understanding of Earth's changes that are transforming our most remarkable home. 

The SUMup database is a compilation of surface mass balance (SMB), subsurface temperature and density measurements from the Greenland and Antarctic ice sheets. This 2023 release contains 4 490 442 data points: 1 778 540 SMB measurements, 2 706 413 density measurements and 5 489 subsurface temperature measurements. This is respectively 1 477 132, 420 825 and 4 715 additional observations of SMB, density and temperature compared to the 2022 release. This new release provides not only snow accumulation on ice sheets, like its predecessors, but all types of SMB measurements, including from ablation areas. On the other hand, snow depth on sea ice is discontinued, but can still be found in the previous releases. The data files are provided in both CSV and NetCDF format and contain, for each measurement, the following metadata: latitude, longitude, elevation, timestamp, method, reference of the data source and, when applicable, the name of the measurement group it belongs to (core name for SMB, profile name for density, station name for temperature). Data users are encouraged to cite all the original data sources that are being used. Issues about this release as well as suggestions of datasets to be added in next releases can be done on a dedicated user forum: https://github.com/SUMup-database/SUMup-data-suggestion/issues. Example scripts to use the SUMup 2023 files are made available on our script repository: https://github.com/SUMup-database/SUMup-example-scripts. 

The critical zone (CZ), the dynamic living skin of the Earth, extends from the top of the vegetation canopy through the soil and down to fresh bedrock and the bottom of groundwater. All humans live in and depend on the critical zone. This zone has three co-evolving surfaces: the top of the vegetation canopy, the ground surface, and a deep subsurface below which Earth’s materials are unweathered. The US National Science Foundation supported network of nine critical zone observatories has made advances in three broad critical zone research areas. First, monitoring has revealed how natural and anthropogenic inputs at the vegetation canopy and ground surface cause subsurface responses in water, regolith structure, minerals, and biotic activity to considerable depths. This response in turn impacts above-ground biota and climate. Second, drilling and geophysical imaging now reveal how the deep subsurface of the CZ varies across landscapes, which in turn influences above-ground ecosystems. Third, several mechanistic models providing quantitative predictions of the spatial structure of the subsurface of the CZ have been proposed. Many countries now fund networks of critical zone observatories (CZOs) to measure the fluxes of solutes, water, energy, gas, and sediments in the CZ and some relate these observations to the histories of those fluxes recorded in landforms, biota, soils, sediments, and rocks. Each U.S. observatory has succeeded in synthesizing observations across disciplines; providing long-term measurements to compare across sites; testing and developing models; collecting and measuring baseline data for comparison to catastrophic events; stimulating new process-based hypotheses; catalyzing development of new techniques and instrumentation; informing the public about the CZ; mentoring students and teaching about emerging multi-disciplinary CZ science; and discovering new insights about the CZ. Many of these activities can only be accomplished with observatories. Here we review the CZO experiment in the US and identify how such a network could evolve in the future. Specifically, we recognize the need for the network to study network-level questions, expand the environments under investigation, accommodate both hypothesis testing and monitoring, and involve more stakeholders. We propose a hubs-and-campaigns model that promotes study of the CZ as one unit. Only with such integrative efforts will we learn to steward the life-sustaining critical zone now and into the future. 

Abstract. The critical zone (CZ), the dynamic living skin of the Earth, extends from the top of the vegetative canopy through the soil and down to fresh bedrock and the bottom of the groundwater. All humans live in and depend on the CZ. This zone has three co-evolving surfaces: the top of the vegetative canopy, the ground surface, and a deep subsurface below which Earth's materials are unweathered. The network of nine CZ observatories supported by the US National Science Foundation has made advances in three broad areas of CZ research relating to the co-evolving surfaces. First, monitoring has revealed how natural and anthropogenic inputs at the vegetation canopy and ground surface cause subsurface responses in water, regolith structure, minerals, and biotic activity to considerable depths. This response, in turn, impacts aboveground biota and climate. Second, drilling and geophysical imaging now reveal how the deep subsurface of the CZ varies across landscapes, which in turn influences aboveground ecosystems. Third, several new mechanistic models now provide quantitative predictions of the spatial structure of the subsurface of the CZ.Many countries fund critical zone observatories (CZOs) to measure the fluxes of solutes, water, energy, gases, and sediments in the CZ and some relate these observations to the histories of those fluxes recorded in landforms, biota, soils, sediments, and rocks. Each US observatory has succeeded in (i) synthesizing research across disciplines into convergent approaches; (ii) providing long-term measurements to compare across sites; (iii) testing and developing models; (iv) collecting and measuring baseline data for comparison to catastrophic events; (v) stimulating new process-based hypotheses; (vi) catalyzing development of new techniques and instrumentation; (vii) informing the public about the CZ; (viii) mentoring students and teaching about emerging multidisciplinary CZ science; and (ix) discovering new insights about the CZ. Many of these activities can only be accomplished with observatories. Here we review the CZO enterprise in the United States and identify how such observatories could operate in the future as a network designed to generate critical scientific insights. Specifically, we recognize the need for the network to study network-level questions, expand the environments under investigation, accommodate both hypothesis testing and monitoring, and involve more stakeholders. We propose a driving question for future CZ science and a hubs-and-campaigns model to address that question and target the CZ as one unit. Only with such integrative efforts will we learn to steward the life-sustaining critical zone now and into the future.