Geology topics

Kenneth Elgersma

Publications and source records attributed to Kenneth Elgersma.

3 recordsLinked to original sources

USGS2023

Mid-contract management alters conservation reserve program vegetation in the central and western United States

Disturbances such as grazing, fire, and burrowing are historically important in North American grasslands, and plans for restoring disturbance regimes are often required for successful restoration. The U.S. Department of Agriculture’s Conservation Reserve Program (CRP) has become the dominant grassland restoration mechanism in many areas, and requires planned disturbances known as mid-contract management (MCM). We recorded evidence of MCM in CRP fields across a 14-state region of the western and central United States, then revisited fields after one to five years to characterize bare ground and vegetative cover and composition using edge-of-road visual surveys. We found a reduced cover of grasses up to five years after MCM, and a concomitant increased cover of flowering forbs and diversity of pollinator-friendly forbs. There was little measurable change in overall plant cover or bare ground cover between one and five years after MCM, though bare soil cover did increase slightly. Baseline tree and shrub covers were very low on average but highly variable due to outliers with high woody cover. After MCM, the presence of woody vegetation remained low and relatively constant. Grazing and haying resulted in a lower probability of noxious grass presence than mowing or disking, but haying and disking were better for inhibiting the presence of noxious forbs. These results show that MCM can be a useful tool for maintaining vegetation quality. The results also point to an important need to understand factors that influence the effects of MCM, including disturbance technique, disturbance frequency, drought, and climate.

Ecological Restoration↗

USGS2023

Persistence and quality of vegetation cover in expired Conservation Reserve Program fields

For nearly 40 years, the Conservation Reserve Program (CRP) has implemented practices to reduce soil erosion, improve water quality, and provide habitat for wildlife and pollinators on highly erodible cropland in the United States. However, an approximately 40,470 ha (10 million acres) decline in enrolled CRP land over the last decade has greatly reduced the program's environmental benefits. We sought to assess the program's enduring benefits in the central and western United States by (1) determining the proportion of fields that persist in CRP cover after contracts expired, (2) identifying the type of agricultural production that CRP fields shift to after contract expiration, (3) comparing the vegetation characteristics of expired CRP fields that are persisting in CRP-type cover with enrolled CRP fields, and (4) identifying differences in management activities (e.g., haying, grazing) between expired and enrolled CRP fields. We conducted edge-of-field vegetation cover surveys in 1092 CRP fields with contracts that expired ≥3 years prior and 1786 currently enrolled CRP fields in 14 states. We found that 41% of expired CRP fields retained at least half of their area in CRP-type cover, with significant variation in persistence among regions ranging from 19% to 84%. When expired fields retained CRP vegetation, bare ground was low in all regions and grass cover was somewhat greater than in fields with current CRP contracts, but at the expense of forb cover in some regions. Evidence of more frequent management in expired CRP fields may explain differences between active and expired CRP fields. Overall, there is clear evidence that CRP-type cover frequently persists and provides benefits for more than three years after contract expiration. Retaining CRP-type cover, post-contract, is an under-recognized program benefit that persists across the central and western United States long after the initial retirement from cropland.

Ecosphere↗

USGS2021

Evaluating establishment of conservation practices in the Conservation Reserve Program across the central and western United States

The U.S. Department of Agriculture's Conservation Reserve Program (CRP) is one of the largest private lands conservation programs in the United States, establishing perennial vegetation on environmentally sensitive lands formerly in agricultural production. Over its 35 year existence, the CRP has evolved to include diverse conservation practices (CPs) while concomitantly meeting its core goals of reducing soil erosion, improving water quality, and providing wildlife habitat. Ongoing threats to grasslands and decreased CRP acreage highlighted the need for a national evaluation of the effectiveness in providing the program's intended benefits. To address this need, we conducted edge-of-field surveys of erosional features, vegetation, and soil cover on 1 786 fields across 10 CPs and 14 central and western states from 2016 to 2018. We grouped practices into three types (grassland, wetland, and wildlife) and states into six regions for analysis. Across practice types, ≥99% of fields had no evidence of rills, gullies, or pedestaling from erosion, and 91% of fields had <20% bare soil cover, with region being the strongest predictor of bare soil cover. Seventy-nine percent of fields had ≥50% grass cover, with cover differing by practice type and region. Native grass species were present on more fields in wildlife and wetland practices compared to grassland practices. Forb cover >50% and native forb presence occurred most frequently in wildlife practices, with region being the strongest driver of differences. Federally listed noxious grass and forb species occurred on 23% and 61% of fields, respectively, but tended to constitute a small portion of cover in the field. Estimates from edge-of-field surveys and in-field validation sampling were strongly correlated, demonstrating the utility of the edge-of-field surveys. Our results provide the first national-level assessment of CRP establishment in three decades, confirming that enrolled wildlife and wetland practices often have diverse perennial vegetation cover and very few erosional features.

Arizona, California, Colorado, Iowa, Idaho, Kansas↗