Life Sciences Commons^™

Exotic Herbivores And Fire Energy Drive Standing Herbaceous Biomass But Do Not Alter Compositional Patterns In A Semiarid Savanna Ecosystem, Virginia D. Preiss, Carissa L. Wonkka, Devan A. Mcgranahan, Alexandra G. Lodge, Matthew B. Dickinson, Kathleen L. Kavanagh, Heath D. Starns, Douglas R. Tolleson, Morgan L. Treadwell, Dirac L. Twidwell Jr, William E. Rogers

Department of Agronomy and Horticulture: Faculty Publications

Questions: Fire regime alterations are pushing open ecosystems worldwide past tipping points where alternative steady states characterized by woody dominance prevail. This reduces the frequency and intensity of surface fires, further limiting their effectiveness for controlling cover of woody plants. In addition, grazing pressure (exotic or native grazers) can reinforce woody encroachment by potentially reducing fine-fuel loads. We investigated the effects of different fire energies on the herbaceous plant community, together with mammalian wildlife herbivory (exotic and native combined) exclusion, to inform best management practices.

Location: Texas semi-arid savanna, southern Great Plains, USA.

Methods: We conducted an …

Spatial Patterns Of Woody Plant Encroachment In A Temperate Grassland, Dillon T. Fogarty, Robert B. Peterson, Dirac Twidwell

Department of Agronomy and Horticulture: Faculty Publications

Context Woody encroachment is the process whereby grasslands transition to a woody-dominated state. This process is a global driver of grassland decline and is ultimately the outcome of increased woody plant recruitment in grasslands. Yet, little is known about how recruitment distances structure spatial patterns of encroachment.

Objectives Here, we develop a recruitment curve to describe the scatter of woody plant recruitment around seed sources and examine how this structures spatial patterns of encroachment.

Methods We developed a recruitment curve for Juniperus virginiana using an encroachment dataset that captures spread from tree plantings into treeless grassland sites in the Nebraska …

Herbaceous Production Lost To Tree Encroachment In United States Rangelands, Scott L. Morford, Brady W. Allred, Dirac L. Twidwell Jr, Matthew O. Jones, Jeremy D. Maestas, Caleb P. Roberts, David E. Naugle

Department of Agronomy and Horticulture: Faculty Publications

1. Rangelands of the United States provide ecosystem services that benefit society and rural economies. Native tree encroachment is often overlooked as a primary threat to rangelands due to the slow pace of tree cover expansion and the positive public perception of trees. Still, tree encroachment fragments these landscapes and reduces herbaceous production, thereby threatening habitat quality for grassland wildlife and the economic sustainability of animal agriculture.

2. Recent innovations in satellite remote sensing permit the tracking of tree encroachment and the corresponding impact on herbaceous production. We analysed tree cover change and herbaceous production across the western United States …

Practice Cost And Size Differences In Invasive Plant Management Strategies: An Empirical Analysis Of Us Great Plains States, Mazbahul G. Ahamad

Department of Agronomy and Horticulture: Faculty Publications

Grassland conservation of the Conservation Stewardship Program in the United States (US) is one of the largest cost-sharing initiatives for protecting grazing land from invasive and woody plants. The practice cost and unit size of various invasive and woody plant management strategies, such as mulching, brush management, and pre- scribed burning, are different from state to state. We aimed to compare and examine the association between practice cost ($/acre[ac]) and standard unit size of practice (acre) of mulching, brush management, and pre- scribed burning strategies in nine US Great Plains states, including Kansas, Montana, Nebraska, New Mexico, North Dakota, Oklahoma, …

Restoring The Fire–Grazing Interaction Promotes Tree–Grass Coexistence By Controlling Woody Encroachment, Jane F. Capozzelli, James R. Miller, Diane M. Debinski, Walter H. Schacht

Department of Agronomy and Horticulture: Faculty Publications

Woody encroachment can convert grasslands and savannas to shrublands and woodlands, so understanding the processes which regulate woody encroachment is necessary to conserve or restore these ecosystems.We hypothesized that recreating the fire–grazing interaction would limit woody encroachment because focal grazing increases fuel accumulation on unburned areas and increases browsing on emergent woody plants in burned areas. This study was conducted in the Grand River Grasslands of Iowa and Missouri (USA) on 11 sites (15.4–35.0 ha). Each site was assigned to one treatment: patch-burn-graze (n = 4), with spatially discrete prescribed fires and free access by cattle (the fire–grazing interaction); graze-andburn …

Land-Use Type As A Driver Of Large Wildfire Occurrence In The U.S. Great Plains, Victoria M. Donovan, Carissa L. Wonkka, David A. Wedin, Dirac Twidwell

Department of Agronomy and Horticulture: Faculty Publications

Wildfire activity has surged in North America’s temperate grassland biome. Like many biomes, this system has undergone drastic land-use change over the last century; however, how various land-use types contribute to wildfire patterns in grassland systems is unclear. We determine if certain land-use types have a greater propensity for large wildfire in the U.S. Great Plains and how this changes given the percentage of land covered by a given land-use type. Almost 90% of the area burned in the Great Plains occurred in woody and grassland land-use types. Although grassland comprised the greatest area burned by large wildfires, woody vegetation …

Social–Ecological Landscape Patterns Predict Woody Encroachment From Native Tree Plantings In A Temperate Grassland, Victoria M. Donovan, Jessica L. Burnett, Christine H. Bielski, Hannah E. Birge, Rebecca Bevans, Dirac L. Twidwell Jr, Craig R. Allen

Department of Agronomy and Horticulture: Faculty Publications

Afforestation is often viewed as the purposeful planting of trees in historically non-forested grasslands, but an unintended consequence is woody encroachment, which should be considered part of the afforestation process. In North America’s temperate grassland biome, Eastern redcedar (Juniperus virginiana L.) is a native species used in tree plantings that aggressively invades in the absence of controlling processes. Cedar is a well-studied woody encroacher, but little is known about the degree to which cedar windbreaks, which are advocated for in agroforestry programs, are contributing to woody encroachment, what factors are associated with cedar spread from windbreaks, nor where encroachment …