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Abstract The southern Great Plains of the USA has great potential to produce biofuel feedstock while minimizing the dual stresses of woody plant encroachment and climate change. Switchgrass (Panicum virgatum) cultivation, woody biomass captured during removal of the encroaching eastern redcedar (Juniperus virginiana) to restore grasslands and thinning of the native oak forest can provide an integrated source of feedstock and improve ecosystem services. In north‐central Oklahoma, we quantified productivity and ecosystem water use of switchgrass stands and degraded ecosystems encroached by eastern redcedar and compared these to native oak forest and tallgrass prairie ecosystems. We measured aboveground net primary productivity (ANPP) using allometric equations (trees) and clip plots (herbaceous), and evapotranspiration (ET) using a water balance approach from gauged watersheds, and calculated water use efficiency (WUE = ANPP/ET) from 2016 to 2019. Among vegetation cover types, ANPP averaged 5.1, 5.4, 6.0, and 7.8 Mg ha−1 year−1for the prairie, oak, eastern redcedar, and switchgrass watersheds and was significantly greater for switchgrass in 2018 and 2019 (2 and 3 years post establishment) when it reached 8.6 Mg ha−1 year−1. Averaged across 2017–2019, ET was significantly greater in the forested watersheds than the grassland watersheds (1022 mm year−1for eastern redcedar, 1025 mm year−1for oak, 874 mm year−1for prairie, and 828 mm year−1for switchgrass). The mean WUE was significantly greater (9.47 kg ha−1 mm−1) for switchgrass than for the prairie, eastern redcedar, and oak cover types (6.03, 6.02, and 5.31 kg ha−1 mm−1). Switchgrass offered benefits of greater ANPP, less ET, and greater WUE. Our findings indicate that an integrated biofuel feedstock system that includes converting eastern redcedar encroached areas to switchgrass and thinning the oak forest can increase productivity, increase runoff to streams, and improve ecosystem services.
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This content will become publicly available on February 1, 2026
Quantitative assessment of ecosystem services in diverse land uses within the forest-grassland transition zone of southern Great Plains, USA
Ecosystem services, essential for supporting life, are increasingly being altered by anthropogenic activities. This study focuses on the Cross Timbers ecoregion of the southern Great Plains, USA, where oak woodland and grassland co-exist. However, grasslands are rapidly transitioning to woodlands through a process known as woody plant encroachment, or are being considered for switchgrass biofuel production. Our objectives were to quantify the supporting (plant biodiversity, aboveground net primary productivity), provisioning (water quantity, forage production), regulating (soil organic carbon, flood regulation), and cultural services (hunting-based recreation, aesthetics) of four land use types—tallgrass prairie, oak woodland, eastern redcedar woodland, and switchgrass biofuel production—using the Millennium Ecosystem Assessment Framework. We integrated these services into an ecosystem sustainability index. Results showed that tallgrass prairie provided balanced services and ranked highest in this index. Eastern redcedar and switchgrass exhibited an imbalance in services, while oak woodland’s ranking varied with normalization methods. Our results highlight the need for grassland conservation by curtailment of eastern redcedar expansion. While oak woodland ranks high in cultural services, its restoration is recommended to enhance multiple ecosystem services. This study provides a roadmap for quantitatively evaluating ecosystem services to inform management decisions for ecosystem transitions and promote regional sustainability. Future research should broaden stakeholder engagement and explore integrated land use strategies within large watersheds encompassing multiple land uses to enhance regional environmental sustainability.
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- Award ID(s):
- 2216648
- PAR ID:
- 10590257
- Publisher / Repository:
- science direct
- Date Published:
- Journal Name:
- Ecosystem Services
- Volume:
- 71
- Issue:
- C
- ISSN:
- 2212-0416
- Page Range / eLocation ID:
- 101697
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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