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Monitoring the Impact of Grazing on Rangeland Conservation Easements Using MODIS Vegetation Indices

Monitoring the effects of grazing on rangelands is crucial for ensuring sustainable rangeland ecosystem function and maintaining its conservation values. Residual dry matter (RDM), the dry grass biomass left on the ground at the end of the grazing season, is a commonly used proxy for rangeland condition in Mediterranean climates. Moderate levels of RDM are correlated with soil stability, forage production, wildlife habitat, and diversity of native plants. Therefore RDM is widely monitored on rangeland conservation properties. Current ground-based methods for RDM monitoring are expensive, are labor intensive, and provide information in the fall, after the effects of grazing have already occurred. In this paper we present a cost-effective, rapid, and robust methodology to monitor and predict RDM using Moderate Resolution Imaging Spectroradiometer (MODIS) satellite data. We performed a time series analysis of three MODIS-based vegetation indices (VIs) measured over the period 2000-2012: Normalized Difference Vegetation Index (NDVI), Leaf Area Index (LAI), and Fraction of Photosynthetically Active Radiation (FPAR). We examined the correlation between the four VIs and fall RDM measured at The Nature Conservancy's Simon Newman Ranch in central California. We found strong and significant correlations between maximum VI values in late spring and RDM in the fall. Among the VIs, LAI values had the most significant correlation with fall RDM. MODIS-based multivariate models predicted up to 63% of fall RDM. Importantly, maximum and sum VIs values were significantly higher in management units with RDM levels in compliance with RDM conservation easement terms compared with units out of compliance. On the basis of these results, we propose a management model that uses time series analysis of MODIS VIs to predict forage quantities, manage stocking rates, and monitor rangeland easement compliance. This model can be used to improve monitoring of rangeland conservation by providing information on range conditions throughout the year

Near-surface ocean temperature & salinity measurements (using YSI and Castaway) during the summer component of the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) campaign in the Central Arctic Ocean, July – September 2020

This dataset contains upper ocean temperature and salinity profiles made during July – September, 2020 as part of the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition in the Central Arctic. The primary aim of these profiles was to capture the stratification of the upper ocean due to meltwater input throughout the summer melt season and the transition to fall freeze-up. The dataset includes data from two instruments: (i) YSI probe, and (ii) Sontek Castaway. The YSI probe was used to take point measurements of temperature and salinity, allowing for more fine-scale profiles in the upper couple of meters. The Sontek Castaway is a small conductivity, temperature, and depth (CTD) device that was used to make profiles over the upper 10s of meters, here typically in complement to the YSI observations, and are processed to 15 centimeters (cm) vertical resolution. Profiles were made in two primary locations: (i) near-surface of leads surrounding the sea ice floe, using both YSI and Castaway, and (ii) upper ocean directly beneath the sea ice, typically using YSI only. A small number of additional observations were made in coincident melt ponds and the upper ocean directly underneath. Details of collection and processing methods, including quality control for both instruments, can be found in data archive descriptions

Near-surface ocean temperature & salinity measurements (using YSI and Castaway) during the summer component of the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) campaign in the Central Arctic Ocean, July – September 2020

This dataset contains upper ocean temperature and salinity profiles made during July – September, 2020 as part of the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition in the Central Arctic. The primary aim of these profiles was to capture the stratification of the upper ocean due to meltwater input throughout the summer melt season and the transition to fall freeze-up. The dataset includes data from two instruments: (i) YSI probe, and (ii) Sontek Castaway. The YSI probe was used to take point measurements of temperature and salinity, allowing for more fine-scale profiles in the upper couple of meters. The Sontek Castaway is a small conductivity, temperature, and depth (CTD) device that was used to make profiles over the upper 10s of meters, here typically in complement to the YSI observations, and are processed to 15 centimeters (cm) vertical resolution. Profiles were made in two primary locations: (i) near-surface of leads surrounding the sea ice floe, using both YSI and Castaway, and (ii) upper ocean directly beneath the sea ice, typically using YSI only. A small number of additional observations were made in coincident melt ponds and the upper ocean directly underneath. Details of collection and processing methods, including quality control for both instruments, can be found in data archive descriptions