Improving Plant Community
Productivity, Structure and Function
Focus Resource Concern for April 2012
PHOENIX, April. 3, 2012 – Improving plant community productivity, structure and function is a resource concern which occurs across all of our land uses in Arizona. When referring to plant communities, productivity pertains to the weight of plant production as compared to what is expected for a healthy site. Structure refers to whether or not all of the representative plant types that would be expected on a healthy site are present. Function refers to the ability of the vegetative groups to carry out their healthy life cycles and contribute to the plant community as a whole. All agricultural products that are produced start at the plant level, whether the end product is lumber, livestock, crops or forage. Wildlife is also completely dependent upon the condition of the plant community and function such as natural fire regimes, overland flow and plant species diversity. NRCS has several practices that are designed to improve plant communities. On crop and pasture lands, the primary concern is to produce yields which are close to the county average while maintaining healthy soil and adequate cover. On rangelands and forests, the primary concern is to maintain plant communities that are close to the productivity and variety that would be expected for the conditions that the producer is managing for, while maintaining adequate cover. All land uses share concerns for wildlife, threatened and endangered plant species and species of concern, along with controlling noxious and invasive plants. Evaluating productivity includes inventorying for signs of stress due to management, disease, insect damage or composition from invasive species. The benefits of improving plant communities, impacts almost all resource concerns including soil erosion and quality, water quality and quantity, air quality and animal concerns both domestic and wildlife.
On croplands, plant productivity, health, and vigor are considered a resource problem when crop production is less than 80% of the average crop yields for your county. NRCS uses county crop reports, developed by the Arizona National Agricultural Statistics Service, to determine the average county crop yield. During the development of the Conservation Plan and when completing the cropland inventory workbook, it is important for the farmer to document their crop yields as well as any reasons, suspected or known, for reduced yields. Reasons include diseases, insect pests, salinity, poor quality soil, lack of nutrients, poor application of irrigation water, and poor utilization of precipitation.
NRCS practices used to address this concern on cropland include; conservation crop rotation, cover crops, residue management (seasonal, strip till/no-till, mulch, and ridge till), nutrient management, pest management and irrigation water management.
On rangelands, plant community health is measured by comparing the productivity and make up of each type of plant community to the expectations defined in its corresponding ecological site description. Rangeland health ratings should also be assessed to look at the overall biotic integrity of each site. The nutrient value and the palatability of the forage plants may also be important factors to assess. Plants which are endangered threatened or are recognized as declining or are species of concern, may need special considerations. Another concern on rangelands is to minimize the presence and spread of noxious species and invasive plants. Proactive measures such as
brush management may be in order when financially feasible.
NRCS practices that are designed to improve plant community productivity, structure and function on rangelands include: prescribed grazing, prescribed burning, brush management, grazing land mechanical treatment, range planting, fence and herbaceous weed control. On riparian sites occurring within rangelands, the practices that are designed to improve plant community productivity, structure and function include; prescribed grazing, riparian herbaceous cover and riparian forest buffer.
On irrigated pastures, plant condition is considered a resource problem when the Pasture Condition Score is 35 or less and production is below 70% of the county average yield for alfalfa. The Pasture Condition Score is computed by completing a score sheet that the NRCS has developed which considerers many factors effecting pasture including; desirable plants, cover, diversity, residue, vigor, amount of legumes, uniformity of use, erosion, soil condition and insects and disease. Other possible resource concerns on irrigated pastures may include noxious species, invasive plants and threatened and endangered species and species of concern.
NRCS practices used to address these concerns on irrigated pasture include; forage harvest management, irrigation water management, nutrient management, pest management, prescribed grazing, salinity and sodic soil management and fence.
On forest lands, plant community health is measured by comparing the productivity, canopy cover and/or density of each plant community to the expectations defined in its corresponding ecological site description. Management of the forest through thinning, fire management, etc. will help to maintain a healthy forest and improve productivity, structure and function. Ensure that over thinning does not occur as this may reduce wildlife habitat quality. Where possible, wildfire risks should be reduced to protect life and
property. Threatened and endangered species or species of concern may need special considerations. Another concern on forest lands is the introduction and spread of noxious and invasive plants. Managing for healthy, productive forests will minimize the spread and establishment of these undesirable species.
NRCS practices that are designed to improve plant community productivity, structure and function on forestlands include: prescribed grazing, tree/shrub establishment, prescribed burning, forest stand improvement, herbaceous weed control and silvopasture establishment. On riparian sites within forest lands the practices that are designed to improve plant community productivity, structure and function include: prescribed grazing, riparian herbaceous cover and riparian forest buffer.
Healthy, productive plant communities have positive impacts across all of the agricultural land uses in Arizona. Almost all of the recognized resource concerns in our state could be addressed by having a productive and functioning plant community in place. Maintaining and improving plant communities should be one of the primary goals of any land manger, whether the final result is intended to be hay, calves, cotton, quail, flowing streams or firewood. It all starts with the plants.