Grass-Cast

Grass-Cast Tutorial Webinar

The Grassland Productivity Forecast, or Grass-Cast, is an experimental model that generates map-based forecasts of grassland productivity, offering a potential new tool in the land manager’s drought contingency planning toolbox for grazing lands. The tool is available in the Great Plains and has recently expanded to the Southwest. In this webinar, Melannie Hartman, Senior Research Associate with Colorado State University and the Grass-Cast Production Team, presented on Grass-Cast and the three-stage process of developing and updating the model each growing season.
Check out the Grass-Cast website here!

Grass-Cast: A New Experimental Rangeland Productivity Forecast Expands to the Southwest Region

Every spring, ranchers face the same difficult challenge—trying to guess how much grass will be available for livestock to graze during the upcoming season. Since May 2019, an innovative Grassland Productivity Forecast or “Grass-Cast” has been helping producers in the northern and southern Great Plains reduce this economically important source of uncertainty. Officially launched this spring, Grass-Cast is now available to producers throughout New Mexico and Arizona.
Every spring, ranchers face the same difficult challenge—trying to guess how much grass will be available for livestock to graze during the upcoming season. Since May 2019, an innovative Grassland Productivity Forecast or “Grass-Cast” has been helping producers in the northern and southern Great Plains reduce this economically important source of uncertainty. Officially launched this spring, Grass-Cast is now available to producers throughout New Mexico and Arizona.
Grass-Cast uses over 30 years of historical data about weather and vegetation growth—combined with seasonal precipitation forecasts—to predict if rangelands in localized areas (6-miles by 6-miles in size) are likely to produce above-normal, near-normal, or below-normal amounts of vegetation for grazing.
Grass-Cast can provide ranchers and rangeland managers with an indication of what productivity could be like in the upcoming growing season relative to their area’s 30+ year history. Grass-Cast also gives ranchers a view of rangeland productivity in the broader region to help with larger-scale decision making, such as determining where grazing resources might be more plentiful if their own region is at risk from drought.
Producers should not rely on Grass-Cast as a sole source for making management decisions. Similarly, public land managers should not use Grass-Cast as a sole source of information for setting stocking rates, determining turnout dates, or for other aspects of lease agreements, allotments or permits.
The first publicly available forecast for the Southwest was released in May 2020, specifically for the spring season (which ended on May 31). Grass-Cast maps for the Southwest’s summer growing season will be posted to the Grass-Cast website in mid-June. These maps will provide productivity estimates for rangelands at the peak of the growing season.
Grass-Cast’s accuracy improves as the growing season unfolds, so it should be consulted more than just once during the growing season. The grassland productivity forecasts are updated every two weeks to incorporate newly observed weather data and emerging trends in growing conditions.
Grass-cast is the result of collaborations between the U.S. Department of Agriculture (USDA) Agricultural Research Service (ARS), Climate Hubs, and Natural Resources Conservation Service (NRCS); the National Drought Mitigation Center (NDMC); Colorado State University and the University of Arizona. Funding from USDA ARS and NRCS, as well as NDMC and the USGS has supported Grass-Cast’s expansion to the Southwest region.
Visit the Grass-Cast website (https://grasscast.unl.edu/) for updates, the latest maps, and other resources.
Grass-Cast contact: Dannele Peck, Director, USDA Northern Plains Climate Hub, dannele.peck@usda.gov
USDA Southwest Climate Hub contact: Emile Elias, Director, emile.elias@usda.gov  
Authors: Dannele Peck, Emile Elias and Lauren Kramer
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Riparian/Bosque:

Mesquite (Prosopis spp.) forests or Bosques are unique and biodiverse riparian forests. Bosques occur primarily along high floodplains in riparian ecosystems below 1200 m in elevation. Today, bosques are composed of dense stands of small young trees. Mesquite is the dominant overstory species with a variety of small shrubs and herbaceous plants making up the understory. With a deep root system almost reaching the water table and a symbiotic relationship with nitrogen-fixing bacteria, Mesquite is a highly productive species promoting biodiversity and providing habitat to wildlife. With this high biodiversity, Mesquite Bosques has a higher density of breeding bird species than any other habitat in the southwest (Stromberg, 1993).

Species Composition

There are three native mesquite species found in the Bosques of the southwest; honey mesquite (Prosopis glandulosa) and velvet mesquite (P. velutina) which are in riparian and upland ecosystems and screwbean mesquite or tornillo (P. pubescens) which is restricted to riparian ecosystems and floodplains. Less than 25% of overstory trees in bosques are species other than mesquite (Stromberg, 1993) mainly including cottonwood and willow species (Carothers et al., 2020) (table x). Bosques have a middle stratum comprised of vine and shrub species and an herbaceous understory (Stromberg, 1993).

Table 4. Bosque Overstory Vegetation Species. Adapted from Stromberg (1993)

Common Name Scientific Name
Honey mesquiteProsopis glandulosa
Velvet mesquiteProsopis velutina
Screwbean mesquite/tornilloProsopis pubescens
Fremont cottonwoodPopulus fremontii
Goodding willowSalix gooddingii
Catclaw acaciaAcacia gregii Gray
Netleaf hackberryCeltis reticulata
Blue palo verdeCercidium floridum
Arizona walnutJuglans major
Texas muberryMorus microphylla
Desert willowChilopsis linearis
Velvet AshFraxinus pennsylvanica Marsh, ssp. velutina
Mexican elderSambucus mexicana
SoapberrySapindus saponariaL. var. drummondii


Historical Conditions

Historically, Bosques were the most abundant riparian forest type in the southwest. At one point, these forests occupied floodplains and often spanned hundreds of kilometers along rivers such as the Gila and Colorado (Stromberg, 1993). Today, bosques are significantly reduced to remnants as anthropogenic changes have eliminated or significantly reduced this forest type. Many species rely on Bosques so this reduction in forest area, has also led to a loss of other plant and animal species (Carothers et al., 2020; Stromberg, 1993).

Climate Impacts 

Human activities such as groundwater pumping, land clearing, and livestock grazing threaten Southwestern Bosques. Few bosques remain and few to none are in pristine condition (Stromberg, 1993). Despite the significant decline from historic composition, Bosques are well-adapted to arid environments. Mesquites have Dimorphic root with a deep tap root that reach alluvial aquifers and lateral roots that reach surface water and flooding (Leenhouts et al., 2006), allow them to replace willow and cottonwood in these systems (Carothers et al., 2020) escape seasonal droughts by storing viable seeds in seed banks, long life span (Stromberg, 1993).