PS 4-43 - Challenges and importance of incorporating forest and wild land ecosystems in the National Coordinated Soil Moisture Monitoring Network

Background/Question/Methods

Many platforms to measure soil moisture are deployed across various ecosystems in the U.S. Unfortunately, there is no national network that monitors soil moisture dynamics across multiple spatial and temporal scales. Forest ecosystems are particularly challenging due to measurement gaps across complex landscapes and considerable variation in soil properties compared to more homogeneous agricultural lands. Additionally, with increasing climatic stressors threatening the sustainability of forests, there is a growing need for new approaches to monitor soil moisture in these lands. Access to readily available soil moisture and forest condition information will increase the capacity of forest managers to adopt proactive strategies in response to drought and other stressors.

To address these challenges the Forest Service (FS) in conjunction with various partners have adopted four core activities: (1) review current literature and data and identify knowledge gaps, (2) identify and expand existing monitoring networks in forest ecosystems, (3) utilize monitoring and remotely sensed data to develop useful soil moisture products to assist managers, and (4) create a centralized data repository. The FS has developed partnerships with the Natural Resource Conservation Service (NRCS), various state mesonets, and with the National Integrated Drought Information System (NIDIS) to develop the network.

Results/Conclusions

Roughly 20% of all in situ soil moisture monitoring occurs in forest ecosystems across 14 different networks, suggesting the lack of standardization of these measurements. Additionally, many of the sites lack data on soil characteristics especially at tree rooting depths. Therefore, large gaps exist in our capacity to measure and understand soil moisture fluctuations in forest ecosystems and resultant impacts. Even with these gaps, the review suggests a strong potential for expansion into forested lands. For example, the Remote Automatic Weather Station (RAWS) network, which has roughly 1000 permanently positioned meteorological stations in forest and grassland ecosystems, has the potential for adding soil moisture sensors. Other opportunities will be discussed, e.g., the new National Soil Survey focused on dynamic soil properties, use of biophysical models and remotely sensed data to fill in the spatial gaps in complex terrain, building on existing site intensive monitoring networks to quantify forest ecosystem water budgets, and participation with the National Coordinated Soil Moisture Monitoring Network (NCSMMN). Further research is needed to improve the ability for remote sensing to assess soil moisture beneath plant canopies and to scale those measurements via monitoring and modelling to those most useful for management of forests in complex terrain.