Redcedar Encroachment Research Articles

Eastward shift in Juniperus virginiana distribution range under future climate conditions in the Southern Great Plains, United States

Eastern redcedar (Juniperus virginiana, redcedar) is a major woody species encroaching upon the native grasslands and forests of the southern Great Plains (SGP), representing a significant threat to regional ecosystem services. Future climate change is anticipated to influence redcedar habitat suitability, changing the probability of further encroachment and reshaping its spatial distribution. In this study, we trained seven Species Distribution Models (SDMs) with redcedar records from the USDA Forest Inventory Analysis database and used the ensemble of these SDMs to simulate redcedar distribution probability under current and future climate conditions in Kansas, Oklahoma, and Texas. Results reveal a distinct east-to-west gradient of decreasing distribution probability in the study domain, primarily driven by climate aridity. Throughout the 21st century, the optimal range of aridity for redcedar habitat is projected to shift eastwards by 0.7° (≈ 58 km) under the RCP45 climate scenario and 1.3° (≈ 108 km) under the RCP85. Accordingly, the suitable habitat will shift eastward by 0.6° (≈ 49 km) in the RCP45 and by 1.2° (≈ 103 km) in the RCP85. The proportion of unsuitable habitat will increase from 40.2 % of the study domain during 2000 – 2019 to 48 % in the RCP45 and 54.2 % in the RCP85 during 2080 – 2099. Additionally, highly suitable land areas will decrease from 10.4 % of the study domain during 2000 – 2019 to 1.3 % in the RCP45 and 0 % in the RCP85 by the end of this century. This study suggests a low likelihood of further redcedar encroachment in the west of the SGP states under future climates, while anticipating continued expansion in the east, gradually replacing the existing oak forests and rangelands. The findings provide valuable insights for prioritizing WPE management resources and contribute to our understanding of future changes in the SGP vegetation composition and their impacts on ecosystem dynamics.

Effective stakeholder engagement in environmental problem-solving though group model building: An Oklahoma case study

Stakeholder engagement is a vital, yet under-accessed and under-studied, resource for tackling wicked environmental problems. This paper examines mental models – cognitive representations of “real” systems – refined through group model building (GMB) with stakeholders concerned with environmental issues in the US state of Oklahoma. During GMB, a diverse group of high-level decision makers met with a variety of physical and social scientists to collaborate on mental models concerning three environmental focus areas in Oklahoma: encroachment of eastern red cedar, grid and infrastructure resilience, and marginal water use and re-use. We ask: how do individuals from diverse stakeholder groups describe causes and consequences of key environmental problems in Oklahoma? Results from this analysis advance efforts toward developing socially sustainable solutions for environmental problems in Oklahoma and beyond.

The combined impact of redcedar encroachment and climate change on water resources in the Nebraska Sand Hills

The Nebraska Sand Hills (NSH) is considered a major recharge zone for the High Plains Aquifer in the central United States. The uncontrolled expansion of the eastern redcedar (Juniperus Virginiana) under climate warming is posing threats to surface water and groundwater resources. The combined impact of land use and climate change on the water balance in the Upper Middle Loup River watershed (4,954 km2) in the NSH was evaluated by simulating different combinations of model scenarios using the Soil Water Assessment Tool (SWAT) model. A total of 222 climate models were ranked according to the aridity index and three models representing wet, median (most likely), and dry conditions were selected. Additionally, the impacts of carbon dioxide (CO2) emissions on root water uptake were simulated. Four plausible redcedar encroachment scenarios, namely 0.5% (no encroachment), 2.4, 4.6, and 11.9%, were considered in the numerical simulations. We, therefore, built: i) the historical scenario (2000–2019) with the current climate and redcedar cover leading to baseline results; ii) the most-likely future scenario (2020–2099) with projected climate (50th percentile of aridity index distribution) and redcedar encroachment that was estimated by using a combination of neural network and Markov-chain cellular automata model; iii) 16 future scenarios (2020–2099) with different combinations of extreme climate (5th and 95th percentiles of aridity index distribution) and four hypothetical encroachment scenarios (0.5, 2.4, 4.6, and 11.9%). The most-likely climate projection indicates that a warming pattern will be expected with a 4.1°C increase in average over the 100-year period, and this will be associated with lower-than-normal precipitation (P). Nevertheless, the concurrent increase in temperature and CO2 concentration is likely to induce stomata closure by reducing potential (ETp) and actual (ETa) evapotranspiration losses. Projected P and ETa are expected to decrease by 10 and 14% while recharge (R) and discharge (D) are expected to increase by 38 and 30% for the period 2020-2050. For the period 2051-2099, the projected P and ETa are expected to decrease by 8 and 32% while R and D are expected to increase by 140.2 and 40%. Finally, a sensitivity analysis of 16 combined climate and land use scenarios is presented and discussed. The scenario modeling approach presented in this paper can support decision-making by stakeholders for optimal management of water resources.

Exploring Opinions for Using Prescribed Fire to Control Eastern Redcedar (Juniperus virginiana) Encroachment in the Southern Great Plains, United States

Eastern redcedar (Juniperus virginiana) is rapidly encroaching on grasslands in the southern Great Plains. This has several adverse effects on the landscape including increased wildfire risk, decreased water runoff, and reduced forage available for cattle production. Several best management practices have been identified to reduce the spread of eastern redcedar, including the use of prescribed fire. However, numerous barriers exist against the use of prescribed fire such as societal acceptance or liability concerns. The purpose of this study was to determine how stakeholders from government agencies, nongovernmental organizations, and landowners perceive the use of prescribed fire to control eastern redcedar encroachment. The strengths, weaknesses, opportunities, and threats−analytical hierarchical process method was used for data analysis. The study showed that governmental and landowner stakeholders viewed that the negatives associated with prescribed fire outweigh the potential benefits. Nongovernmental organization stakeholders had differing opinions, and they were largely supportive of using prescribed fire. The results suggest that there is a need for tailored outreach to alleviate the concerns associated with risks and liabilities, as escaped prescribed fires are highly uncommon.

Impact of Eastern Redcedar encroachment on water resources in the Nebraska Sandhills

Worldwide, tree or shrub dominated woodlands have encroached into herbaceous dominated grasslands. While very few studies have evaluated the impact of Eastern Redcedar (redcedar) encroachment on the water budget, none have analyzed the impact on water quality. In this study, we evaluated the impact of redcedar encroachment on the water budget in the Nebraska Sand Hills and how the decreased streamflow would increase nitrate and atrazine concentrations in the Platte River. We calibrated a Soil and Water Assessment Tool (SWAT model) for streamflow, recharge, and evapotranspiration. Using a moving window with a dilate morphological filter, encroachment scenarios of 11.9 %, 16.1 %, 28.0 %, 40.6 %, 57.5 %, 72.5 % and 100 % were developed and simulated by the calibrated model. At 11.9 % and 100 % encroachment, streamflow was reduced by 4.6 % and 45.5 %, respectively in the Upper Middle Loup River, a tributary to the Platte River. Percolation and deep aquifer recharge increased by 27 % and 26 % at 100 % encroachment. Streamflow in the Platte River, a major water source for Omaha and Lincoln, would decrease by 2.6 %, 5.5 % and 10.5 % for 28 %, 57.5 %, and 100 % encroachment of the Loup River watershed, respectively. This reduction in streamflow could increase nitrate and atrazine concentrations in the Platte River by 4 to 15 % and 4 to 30 %, respectively. While the density of redcedar is minimal, it is important to manage their encroachment to prevent reductions in streamflow and potential increases in pollutant concentrations.

54 Eastern Red Cedar Targeted Grazing with Goats: Tree Height Significance

Abstract Eastern red cedar (ERC; Juniperus Virginiana L.) encroachment into grassland ecosystems, facilitated by fire suppression and overgrazing, threatens the long-term health of the Northern Great Plains. Goats consume juniper through defoliation and debarking, and debarking causes branch death. ERC do not resprout, meaning trunk girdling can effectively kill the tree, making targeted grazing with goats a potential control tool, though little is known about targeted grazing with goats on ERC. The objective of this project is to investigate how goats defoliate and debark ERC of different heights. Moderately stocked (95 AUD∙ha-1) Spanish cross-bred goats grazed 24-hour periods in each of 4 replicate ERC-invaded 0.056 ha paddocks (average 117 trees∙paddock-1). ERC of 5 height classes, up to 250 cm at 50 cm increments, were permanently tagged in each paddock. Defoliation was measured by volume (⅓πr2h) reduction (%) from pre- to post-treatment, branch browse was measured as branches browsed (%) below the browse line, and debarking was measured by trunk debarked (%) below the browse line. Tree height was a significant predictor of defoliation (r2 = 0.63, n = 159, P < 0.001) and debarking (r2 = 0.53, n = 159, P < 0.001). ERC < 100 cm tall were significantly more defoliated (P < 0.05, x̄ = 74%) and ERC 50-100 cm had significantly more branches browsed up to the browse line (P < 0.05, x̄ = 85%), while ERC > 100 cm were significantly more likely to be debarked (P < 0.05, x̄ = 45%). Average browse line for trees 100-250 cm was 186 cm. Our results suggest that goats disproportionally defoliate and debark short (1-100 cm) and tall (100-250 cm) ERC trees, respectively. Moderately stocked targeted grazing with goats could be an effective ERC site pre-treatment for prescribed fire or other control methods.

Economic Feasibility of Mixed-Species Grazing to Improve Rangeland Productivity.

Simple SummaryThe encroachment of woody plants, including the eastern redcedar, in the central Great Plains is reaching critical levels. This encroachment impacts the profitability of cattle grazing operations, and potentially the ability to meet consumer demand for beef products due to lower stocking rates. Even though chemical and fire control are currently being used, the incorporation of small ruminants such as goats can help control the spread of woody plants, while providing an additional source of revenue and protein. In this analysis, we take a data driven approach to analyzing the potential for success utilizing different combination of chemicals, fire, breeding goats and stocker goats to control woody plant encroachment. Given our assumptions, the combination with the highest net present value was cattle, controlled burning and breeding goats.Pasture and grazing land in the southern and central Great Plains is being invaded by woody species, especially eastern redcedar. As a result of woody plant encroachment, cattle production on native rangeland is becoming less profitable because stocking rates must be decreased. Eastern redcedar encroachment can be controlled by grazing management, herbicide use, prescribed fire, mechanical control and mixed species grazing. This study utilizes traditional management practices, prescribed fire and three types of mixed species grazing operations to determine the most economically feasible way to manage redcedar encroachment on rangeland. The cost-benefit analysis in this study found that the source of redcedar management on rangeland with the highest net present value was the use of a breeding goat operation in which goats were grazed alongside cattle with the use of prescribed fire. This suggests that producers who are fighting redcedar encroachment will likely be able to implement a mixed species grazing operation with breeding goats to better manage their land and increase returns.

Stand-Level Transpiration Increases after Eastern Redcedar (Juniperus virginiana L.) Encroachment into the Midstory of Oak Forests

Eastern redcedar (Juniperus virginiana L., redcedar) encroachment is transitioning the oak-dominated Cross-Timbers of the southern Great Plain of the USA into mixed-species forests. However, it remains unknown how the re-assemblage of tree species in a semiarid to sub-humid climate affects species-specific water use and competition, and ultimately the ecosystem-level water budget. We selected three sites representative of oak, redcedar, and oak and redcedar mixed stands with a similar total basal area (BA) in a Cross-Timbers forest near Stillwater, Oklahoma. Sap flow sensors were installed in a subset of trees in each stand representing the distribution of diameter at breast height (DBH). Sap flow of each selected tree was continuously monitored over a period of 20 months, encompassing two growing seasons between May 2017 and December 2018. Results showed that the mean sap flow density (Sd) of redcedar was usually higher than post oaks (Quercus stellata Wangenh.). A structural equation model showed a significant correlation between Sd and shallow soil moisture for redcedar but not for post oak. At the stand level, the annual water use of the mixed species stand was greater than the redcedar or oak stand of similar total BA. The transition of oak-dominated Cross-Timbers to redcedar and oak mixed forest will increase stand-level transpiration, potentially reducing the water available for runoff or recharge to groundwater.

Monitoring conifer cover: Leaf-off lidar and image-based tracking of eastern redcedar encroachment in central Nebraska

Eastern redcedar (Juniperus virginiana L.) encroachment on the Great Plains has led to decreases in biodiversity, water availability, and grazing land while increasing the risk of catastrophic wildfires. Quantifying the current spatial distribution of eastern redcedar can aid land management efforts to combat encroachment, and extending this information over time can improve our understanding of the patterns and drivers of encroachment. We compared several remote sensing methods for mapping percent conifer cover to develop an approach that would be applicable for monitoring eastern redcedar encroachment across the Great Plains to support management goals. Leaf-off lidar was filtered through a novel approach using normalized return intensity and local canopy density to remove residual points pertaining to deciduous trees, which enabled us to calculate percent conifer cover. A sample of the conifer cover derived from leaf-off lidar was then used to test passive imagery-based methods that could be applied over a greater spatiotemporal extent. These imagery-based methods included Spatial Wavelet Analysis applied to very high-resolution imagery and random forest regression modeling with Landsat 8 and Sentinel-2 based predictive layers generated in Google Earth Engine from a single image, seasonal composites, and harmonic regression coefficients produced from an annual time series. Spatial Wavelet Analysis provided high accuracy (~5% RMSE) in areas where conifer cover was less than 10%, but accuracy rapidly decreased with increases in observed cover such that this method had a very low overall accuracy (42.5% RMSE). Landsat 8 and Sentinel-2 based predictors yielded similar performance to each other in models of conifer cover (9.7 to 13.3% RMSE), but seasonal composites from either sensor provided higher predictive power than either use of a single winter image or harmonic regression coefficients. According to recent estimates from the Forest Inventory and Analysis Program, eastern redcedar comprises more than 90% of conifer basal area in 277 counties of the central Great Plains, and thus mapping conifer cover can be assumed to reflect eastern redcedar cover. By applying the LandTrendr algorithm to Landsat seasonal composites we produced stable estimates of eastern redcedar cover from 1984 to 2018 and quantified encroachment as a 2.3% per year increase in eastern redcedar forest, defined as areas with ≥10% redcedar cover. The comparison of these methods and their application through time lays the groundwork for monitoring of redcedar encroachment across the central Great Plains and provides an approach for mapping fractional cover of conifer trees more generally.

Sustainable management of unused eastern redcedar: An integrated spatial and economic analysis approach

The changes in native forest and grassland management regimes following European settlement, particularly fire exclusion, have prompted the growth of fire intolerant woody tree species such as eastern redcedar (Juniperus virginiana). Eastern redcedar is a native species that has encroached into the prairies and forests of the southern Great Plains of the United States. Over the past few decades, the state of Oklahoma has witnessed considerable ecological and economic losses due to the widespread encroachment of eastern redcedar. This study performed an economic impact analysis in conjunction with a spatial analysis to understand the impacts of the introduction of new eastern redcedar-based bioproducts industries on the economy of Oklahoma. The results suggested that the new eastern redcedar industry manufacturing particleboard, mulch, and oil would contribute an additional USD 96 million per year to the economy of Oklahoma, while generating 319 employment opportunities. In addition, the spatial analysis identified two hotspot clusters suggesting that the existing biomass in the northwest and southeast counties of the state could sustain the bioproducts industry for two to ten decades based on the annual feedstock requirement of different operations.

Drought Tolerance and Competition in Eastern Redcedar (Juniperus virginiana) Encroachment of the Oak-Dominated Cross Timbers.

On the dry, western edge of the eastern deciduous forest of the USA (Cross Timbers), the drought-tolerant, evergreen eastern redcedar (Juniperus virginiana) is encroaching into post oak- (Quercus stellata) dominated woodlands. The overall goal of this study was to examine whether the drought tolerance strategies of eastern redcedar provide it a competitive advantage over post oak and whether this is a key attribute facilitating its successful establishment in the Cross Timbers. Specifically, we assessed xylem water potential and leaf gas exchange of these two species growing in single-species stands and in a mixed-species stand. We found that both species exhibit a similar degree of isohydry and close their stomates to the same extent in response to declining xylem water potentials. Both species had similar relative reductions in gas exchange in response to drought, despite differences in xylem anatomy. However, post oak had leaf-level gas exchange rates approximately 5× greater than eastern redcedar during periods of high moisture availability. Therefore, it did not appear that eastern redcedar encroachment into an oak-dominated forest is facilitated by growing season differences in carbon gain, although evergreen eastern redcedar can conduct gas exchange year-round when conditions are favorable while post oak is deciduous. We found that volumetric soil water content (0–45 cm) was lower in the pure eastern redcedar stand than the mixed-species or pure post oak stand which may indicate that eastern redcedar may experience favorable soil moisture conditions when encroaching into open oak woodlands. Moreover, water potentials in eastern redcedar tended to be more negative in pure stands compared to the mixed stand. Our results suggest the two species may be using water from different depths, reducing competition. Overall, our findings indicate that eastern redcedar encroachment into formerly oak-dominated Cross Timbers forests likely will continue under moderate drought, in the absence of fire, with consequences for water budgets, carbon cycling, grazing forage, wildlife habitat, and wildfire risk.

An overview of research into conservation practice effects on soil and water resources in the Upper Washita Basin, Oklahoma, United States

The Fort Cobb Reservoir Experimental Watershed (FCREW) and Little Washita River Experimental Watershed (LWREW), located within the Upper Washita Basin (UWB) in Oklahoma, are part of the Agricultural Research Service (ARS) Benchmark Conservation Effects Assessment Project (CEAP)–Watershed Assessment Studies locations. The CEAP was created in 2003 by the USDA Natural Resources Conservation Service (NRCS) in partnership with USDA ARS and many other partners to quantify the environmental effects of conservation practices (CPs) and programs and to develop the science base for managing the agricultural landscape for environmental quality. The ultimate goal of this study was to present CPs that are expected to work at respective spatial scales, based on the findings of research that has been carried out in these CEAP and other watersheds within the UWB in the last 15 years. A summary of research findings indicates that the effects of CPs on soil and water resources were simulated at various spatial scales. At the large watershed scale, average annual suspended sediment yield at the 786 km² (303 mi²) FCREW outlet was reduced by 86% based on multiple CPs implemented from the 1950s to 2008 by NRCS. Specific quantified effects of studied CPs are presented herein. With the exception of red cedar (<i>Juniperus virginiana</i> L.) removal, single CPs were expected to show improvement of soil and water resources in smaller-scale watersheds. Practices that are expected to improve soil and water resources include grassland conservation from red cedar encroachment (brush control), combined streambank stabilization practices, riparian and filter strip buffer practices, and conversion of cropped area to Bermuda grass (<i>Cynodon dactylon</i> [L.] Pers.).

The ecological and economic determinants of eastern redcedar (Juniperus virginiana) encroachment in grassland and forested ecosystems: A case study from Oklahoma

Frequent fires were used as a management tool to maintain prairies, savannas, and woodlands in the southern Great Plains of the United States. However, fire exclusion beginning in the mid-1900s allowed for the establishment and growth of fire-intolerant species such as eastern redcedar (Juniperus virginiana: ERC) beyond their naturally occurring habitats. Apart from the reduction in burning, wide soil and climate adaptability, and seed dispersal by birds have facilitated the expansion of ERC in the southern Great Plains. The encroachment of ERC has caused heavy ecological and economic losses to Oklahoma and thus has been a major management concern for the past few decades. This study utilized count data modeling to analyze USDA Forest Service's (USFS) Forest Inventory and Analysis (FIA) data to investigate the relationship between available ecological and economic factors and the abundance of ERC in grassland and forested ecosystems of Oklahoma. The results suggested that low site productivity, high basal area, dense canopy, and silt loam soil texture significantly increase the abundance of ERC on a given site. The results also indicated that the rate of ERC encroachment is 3.3% higher in the softwood and 2.0% higher in the miscellaneous forests, compared to the hardwood forests. However, the economic variables of the study such as ownership type, adoption of active management, and proximity to a metropolitan area did not show a significant relationship to the abundance of ERC.

Ecological costs of discrimination: racism, red cedar and resilience in farm bill conservation policy in Oklahoma

AbstractThis article makes the case that the legacy of institutional racism by the United States Department of Agriculture (USDA) is connected to the encroachment of the invasive speciesJuniperus virginiana(eastern red cedar) on farming land. Red cedar's encroachment impacts Black farmers disproportionately in Oklahoma, even as it undermines broader USDA conservation goals and ability to adapt to climate change. As such, this case study illustrates the shortcomings of Farm Bill Conservation Title programs to address ecological issues across the landscape—shortcomings that hinder farmers' ability to carry out long-term adaptation and mitigate risks. Conversely, we show how the work of Oklahoma Black Historical Research Project, Inc. and the Rural Coalition has been vital allies in Black farmers inter-related struggles against racial injustice and red cedar. Thus, we argue community-based organizations have a pivotal, but under-supported, role to play in the shaping and application of farm bill programs and funds.

Impact of Eastern Redcedar Proliferation on Water Resources in the Great Plains USA—Current State of Knowledge

In the Great Plains of the central United States, water resources for human and aquatic life rely primarily on surface runoff and local recharge from rangelands that are under rapid transformation to woodland by the encroachment of Eastern redcedar (redcedar; Juniperus virginiana) trees. In this synthesis, the current understanding and impact of redcedar encroachment on the water budget and water resources available for non-ecosystem use are reviewed. Existing studies concluded that the conversion from herbaceous-dominated rangeland to redcedar woodland increases precipitation loss to canopy interception and vegetation transpiration. The decrease of soil moisture, particularly for the subsurface soil layer, is widely documented. The depletion of soil moisture is directly related to the observed decrease in surface runoff, and the potential of deep recharge for redcedar encroached watersheds. Model simulations suggest that complete conversion of the rangelands to redcedar woodland at the watershed and basin scale in the South-central Great Plains would lead to reduced streamflow throughout the year, with the reductions of streamflow between 20 to 40% depending on the aridity of the climate of the watershed. Recommended topics for future studies include: (i) The spatial dynamics of redcedar proliferation and its impact on water budget across a regional hydrologic network; (ii) the temporal dynamics of precipitation interception by the herbaceous canopy; (iii) the impact of redcedar infilling into deciduous forests such as the Cross Timbers and its impact on water budget and water availability for non-ecosystem use; (iv) land surface and climate interaction and cross-scale hydrological modeling and forecasting; (v) impact of redcedar encroachment on sediment production and water quality; and (vi) assessment and efficacy of different redcedar control measures in restoring hydrological functions of watershed.

Perceptions regarding active management of the Cross-timbers forest resources of Oklahoma, Texas, and Kansas: A SWOT-ANP analysis

The Cross-timbers ecoregion, which stretches from north central Texas, through central Oklahoma, and up into southern Kansas, represents the broad ecotone between the eastern deciduous forest and the grasslands of the southern Great Plains. The region is threatened by both natural and anthropogenic factors including climate variability, the encroachment of eastern redcedar (Juniperus virginiana), and urbanization. In particular, fire exclusion has dramatically changed the structure and composition of the Cross-timbers forests, which historically experienced multiple fires per decade. Active management practices such as prescribed fire, timber thinning, and fuels reduction are largely absent in the Cross-timbers forested ecosystems. This study utilized a mixed-mode data collection method, which involved focus group meetings as well as online survey administration, to determine how stakeholders perceive active management in the Cross-timbers forests. The requisite data were analyzed using the strengths, weaknesses, opportunities, and threats (SWOT)-Analytic Network Process (ANP) framework. The results suggested that presence of healthy and resilient forests and the opportunities associated with increased revenue could be the driving forces in active Cross-timbers management. However, financial burden and uncontrolled fire were recognized as the major obstacles in these efforts. Tailoring appropriate outreach programs can help traditional and non-traditional stakeholders to identify appropriate management solutions in the Cross-timbers.

Forty-Eight Years of Forest Succession: Tree Species Change across Four Forest Types in Mid-Missouri

In the central and eastern United States, many forest ecosystems have undergone recent shifts in composition and structure that may conflict with contemporary management objectives. Long-term forest inventory data were used to determine patterns of forest succession over a 48-year period for four forest types in mid-Missouri: bottomlands, dry ridge and slope, glade-like, and mesic slopes. All forest types increased in stand basal area and overstory quadratic mean diameter through time, with concomitant decreases in the number of midstory trees. Sugar maple (Acer saccharum Marshall) increased in importance value on dry ridge and slope and mesic slope forest types, largely due to the accumulation of trees in smaller diameter classes. White oak (Quercus alba L.) increased in overstory basal area in dry ridge and slope plots through the duration of the study, whereas black oak (Quercus velutina Lam.) and Shumard oak (Quercus shumardii Buckley) decreased in overstory density and basal area through time. Oak stems were nearly absent from the midstory across forest types in the recent sampling, suggesting future challenges for maintaining oak-dominated canopies following attrition of canopy trees through time on upland forest types. In glade-like plots, eastern redcedar (Juniperus virginiana L.) increased in both overstory density and basal area through time, and Shumard oak decreased in density. The importance value of chinkapin oak (Quercus muehlenbergii Engelm.) in the overstory decreased through time in glade-like plots, largely due to the increase in density of eastern redcedar rather than the loss of chinkapin oak from the overstory. The patterns of succession in this forest landscape of mid-Missouri suggest that forest management may be needed to address two common contemporary concerns: (1) the need for increasing oak advance reproduction and recruitment to maintain oak as a canopy species; and (2) reducing eastern redcedar encroachment for glade restoration and management.

Characterizing the encroachment of juniper forests into sub-humid and semi-arid prairies from 1984 to 2010 using PALSAR and Landsat data

Over the past few decades, wide encroachment of eastern redcedar (Juniperus virginiana) and Ashe juniper (Juniperus ashei) into the prairies of the U.S. Great Plains has affected wildlife habitats, forage and livestock production, and biogeochemical cycles. This study investigates the spatio-temporal dynamics of juniper forest encroachment into tallgrass prairies by generating juniper forest encroachment maps from 1984 to 2010 at 30m spatial resolution. A pixel and phenology-based mapping algorithm was used to produce the time series maps of juniper forest encroachment using a combination of Phased Array type L-band Synthetic Aperture Radar (PALSAR) mosaic data from 2010 and Landsat 5 and 7 data (10,871 images from 1984 to 2010). We analyzed the resultant maps to understand the dynamics of juniper forest encroachment at state and county spatial scales and examined juniper occurrence by geographic region and soil type. The juniper forest maps were generated over five multi-year periods: the late 1980s (1984–1989), early 1990s (1990–1994), late 1990s (1995–1999), early 2000s (2000–2004), and late 2000s (2005–2010). We also produced a map of time since stand detection of juniper forests in 2010. Our major findings include: (1) juniper forests have expanded linearly in time at an annual rate of ~40km2/year since 1984; (2) juniper forests had notable spatial clusters in its expansion process; (3) ~65% of juniper forests in 2010 were <15years after stands have been detected; and (4) juniper forests in 2010 were mainly distributed in sandy and loamy soils with relatively low available water storage in the top soils. This study demonstrates the potential of combining a cloud computing platform (Google Earth Engine), time series optical images (Landsat), and microwave images to document the spatial-temporal dynamics of juniper forest encroachment into prairies since the 1980s at the regional scale. The results can be used to study the causes, consequences, and potential future distribution of juniper encroachment, which are relevant to the sustainable management of prairie ecosystems.

Estimating increased fuel loading within the Cross Timbers forest matrix of Oklahoma, USA due to an encroaching conifer, Juniperus virginiana, using leaf-off satellite imagery

Abstract Encroachment of eastern redcedar (ERC; Juniperus virginiana) into the Quercus dominated Cross Timbers region of the Southern Great Plains is an ongoing management issue that affects ecosystem services and wildfire hazard. The location and density of ERC in the forest understory and midstory are important information for fire managers seeking to estimate the behavior of fires or anticipate resources and attack methods needed to contain wildland fires. We developed a method to use remotely sensed, 3-band, satellite imagery to determine ERC presence and abundance within the Cross Timbers forest on 90 Bureau of Indian Affairs Trust Land properties in Pawnee and Payne Counties Oklahoma, USA. We used 130 (0.04 ha) field verification plots to establish the accuracy of the technique and estimate the biomass of the highly flammable ERC to determine the additional fuel loading that ERC encroachment represents. Compared to the field measurements, the satellite imagery identified approximately 50% of the ERC canopy area ([Actual Canopy Area] = 1.9517 ∗ [Classified Canopy Area] + 13.093, r2 = 0.78, n = 124). The relationship between ERC canopy area and ERC aboveground biomass was also determined ([Biomass (kg)] = 4.1839 ∗ [Actual Canopy Area] − 72.206, r2 = 0.71 n = 124). Estimating the biomass of the 90 larger tracts (10–65 ha) based on ERC canopy area, we calculated that ERC canopy cover averaged 21% within the forest matrix and that ERC biomass averaged 6.3 Mg ha−1 which represents a 38% increase in available fuel loading due to ERC encroachment. The addition of the highly flammable, evergreen ERC to the fuel load of the Cross Timbers forest likely increases the potential of wildfire damage. Our results can be used throughout the Cross Timbers region of Texas, Oklahoma, and Kansas, in coordination with fuel and fire simulation models, to inform management related to wildfire and fuel reduction treatments.

Cost to produce liquid biofuel from invasive eastern redcedar biomass

Biomass harvested from invasive plant species has been proposed for use as lignocellulosic feedstock for the production of advanced biofuels as a way to mitigate the indirect land use issues associated with the production of dedicated energy crops. Encroachment of eastern redcedar (Juniperus virginiana L.) has reduced the forage productivity of North American Great Plains grasslands ranging from Texas in the South to Alberta in the North. The objective of this study is to develop and demonstrate a modeling system that can be used to determine the minimum selling price of biofuel. A fast pyrolysis process that exclusively uses eastern redcedar biomass to produce gasoline and diesel blend stock is assumed. A mixed integer mathematical programming model is constructed and applied to a 15 county case study region from which eastern redcedar may be collected. The modeling system considers the growth rate of unharvested trees to determine the optimal biorefinery location, the optimal harvest locations for each of 20 years, and the minimum selling biofuel price. To fulfill 2 Gg d−1 feedstock requirements for the expected life of the biorefinery, 73% of the trees growing in year zero in the case study region would be required. For a 313 dm3 Mg−1 conversion rate, and with biorefinery ownership, operating and maintenance cost of 630 $ m−3, the expected cost to deliver feedstock is estimated to be 61 $ Mg−1, and the estimated minimum selling biofuel price is 830 $ m−3.