"Functional consequences of animal community changes in managed grasslands: An application of the CAFE approach"

"Functional consequences of animal community changes in managed grasslands: An application of the CAFE approach"

This article was accepted for online publication Oct. 25, 2023 in the journal Ecology. Access online via the permanent weblink (DOI): https://doi.org/10.1002/ecy.4192

Abstract

In the midst of an ongoing biodiversity crisis, much research has focused on species losses and their impacts on ecosystem functioning. The functional consequences (ecosystem response) of shifts in communities are shaped not only by changes in species richness, but also by compositional shifts that result from species losses and gains. Species differ in their contribution to ecosystem functioning, so species identity underlies the consequences of species losses and gains on ecosystem functions. Such research is critical to better predict the impact of disturbances on communities and ecosystems. We used the ‘Community Assembly and the Functioning of Ecosystems’ (CAFE) approach, a modification of the Price equation to understand the functional consequences and relative effects of richness and composition changes in small non-volant mammal and dung beetle communities as a result of two common disturbances in North American prairie restorations – prescribed fire and reintroduction of large grazing mammals. Previous research in this system shows dung beetles are critically important decomposers, while small mammals modulate much energy in prairie food webs. We found that dung beetle communities were more responsive to bison reintroduction and prescribed fires than small non-volant mammals. Dung beetle richness increased after bison reintroduction, with higher dung beetle community biomass resulting from changes in remaining species (context-dependent component) rather than species turnover (richness components); prescribed fire caused a minor increase in dung beetle biomass for the same reason. For small mammals, bison reintroduction reduced energy transfer through the loss of species, while prescribed fire had little impact on either small mammal richness or energy transfer. The CAFE approach demonstrates how bison reintroduction controls small non-volant mammal communities by increasing prairie food web complexity, and increases dung beetle populations with possible benefits for soil health through dung mineralization and soil bioturbation. Prescribed fires, however, have little effect on small mammals and dung beetles, suggesting a resilience to fire. These findings illustrate the key role of re-establishing historical disturbance regimes when restoring endangered prairie ecosystems and their ecological function.

Keywords: bison; community assembly; dung beetle; ecosystem function; prescribed fire; Price equation; small mammal; species richness; tallgrass prairie restoration

Citation

Hogan, Katharine FE, Holly P. Jones, Kirstie Savage, Angela M. Burke, Peter W. Guiden, Sheryl C. Hosler, Erin Rowland‐Schaefer, and Nicholas A. Barber. "Functional consequences of animal community changes in managed grasslands: An application of the CAFE approach." Ecology (2023): e4192.

“Qualitative value of information provides a transparent and repeatable method for identifying critical uncertainty” @RallidaeRule @mlstantial @AbsLawson @mcr_evpi #DecisionScience #rxfire

“Qualitative value of information provides a transparent and repeatable method for identifying critical uncertainty”

Editor's Note: This case study was chosen for the potential relevance of the tool (Vol) for those undertaking formal decision analysis.

This open access article was published February 21, 2023 in Ecological Applications. Access via the permanent web link (DOI). (https://doi.org/10.1002/eap.2824)

Abstract

Conservation decisions are often made in the face of uncertainty because the urgency to act can preclude delaying management while uncertainty is resolved. In this context, adaptive management is attractive, allowing simultaneous management and learning. An adaptive program design requires the identification of critical uncertainties that impede the choice of management action. Quantitative evaluation of critical uncertainty, using the expected value of information, may require more resources than are available in the early stages of conservation planning. Here, we demonstrate the use of a qualitative index to the value of information (QVoI) to prioritize which sources of uncertainty to reduce regarding the use of prescribed fire to benefit Eastern Black Rails (Laterallus jamaicensis jamaicensis), Yellow Rails (Coterminous noveboracensis), and Mottled Ducks (Anas fulvigula; hereafter, focal species) in high marshes of the U.S. Gulf of Mexico. Prescribed fire has been used as a management tool in Gulf of Mexico high marshes throughout the last 30+ years; however, effects of periodic burning on the focal species and the optimal conditions for burning marshes to improve habitat remain unknown. We followed a structured decision-making framework to develop conceptual models, which we then used to identify sources of uncertainty and articulate alternative hypotheses about prescribed fire in high marshes. We used QVoI to evaluate the sources of uncertainty based on their Magnitude, Relevance for decision-making, and Reducibility. We found that hypotheses related to the optimal fire return interval and season were the highest priorities for study, whereas hypotheses related to predation rates and interactions among management techniques were lowest. These results suggest that learning about the optimal fire frequency and season to benefit the focal species might produce the greatest management benefit. In this case study, we demonstrate that QVoI can help managers decide where to apply limited resources to learn which specific actions will result in a higher likelihood of achieving the desired management objectives. Further, we summarize the strengths and limitations of QVoI and outline recommendations for its future use for prioritizing research to reduce uncertainty about system dynamics and the effects of management actions.

Keywords: adaptive management; decision analysis; Eastern Black Rail; endangered species; hunted species; marsh birds; Mottled Duck; structured decision-making; value of information; Yellow Rail

Citation

Stantial, Michelle L., Abigail J. Lawson, Auriel MV Fournier, Peter J. Kappes, Chelsea S. Kross, Michael C. Runge, Mark S. Woodrey, and James E. Lyons. "Qualitative value of information provides a transparent and repeatable method for identifying critical uncertainty." Ecological Applications (2023): e2824.

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“Regional dynamics of tick vectors of human disease” @gpfirescience @prairiefiresci @oakfirescience

“Regional dynamics of tick vectors of human disease”

Editor's note: This article addresses ticks for the central United States, with factors including fire frequency, expansion of red ceder woodlands, expansion of prairie reconstruction, and invasive tick species.

This review article was published February 2023 in Current Opinion in Insect Science. Access the article via the permanent web address (DOI). (https://doi.org/10.1016/j.cois.2023.101006)

Summary

The expansion of tick-borne diseases challenges ecologists, epidemiologists, and public health professionals to understand the mechanisms underlying its emergence. The vast majority of tick-borne disease research emphasizes Ixodes spp. and Borrelia burgdorferi, with less known about other Ixodidae ticks that serve as vectors for an increasing number of pathogens of public health concern.

Here, we review and discuss the current knowledge of tick and tick-borne pathogens in an undersurveilled region of the United States.

We discuss how landscape shifts may potentially influence tick vector dynamics and expansion. We also discuss the impact of climate change on the phenology of ticks and subsequent disease transmission.

Increased efforts in the Central Plains to conduct basic science will help understand the patterns of tick distribution and pathogen prevalence. It is crucial to develop intensive datasets that may be used to generate models that can aid in developing mitigation strategies.

Citation

Wimms, Chantelle, Evan Aljundi, and Samniqueka J. Halsey. "Regional Dynamics of Tick Vectors of Human Disease." Current Opinion in Insect Science (2023): 101006.

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“Prescribed fire increases the number of ground-nesting bee nests in tallgrass prairie remnants”

“Prescribed fire increases the number of ground-nesting bee nests in tallgrass prairie remnants”

This article was published Feb. 22, 2023, in Insect Conservation and Diversity.  Access online via the permanent web address (DOI). (https://doi.org/10.1111/icad.12628)

Abstract

Prescribed burning is a common management technique in tallgrass prairie remnants, but there have been few empirical studies that directly examine burning impacts on the nesting preferences and habitat of ground-nesting bees.

We used emergence traps in remnant tallgrass prairies in western Minnesota, USA to determine whether ground-nesting bees prefer to nest in burned or unburned prairies. We estimated the total number of nests made by actively nesting bees in burned and unburned patches by assessing each specimen for wing and mandible wear, sex, and sociality. We also measured characteristics that may influence bee nesting preferences including bare ground, thatch depth, vegetative cover, and the floral community.

We found more nests of actively nesting ground-nesting bees in burned patches than unburned patches, but no differences in effective number of species of ground-nesting bees or community composition. Burned patches had higher amounts of percent bare ground and a thinner thatch layer, but no differences in percent vegetative cover, floral abundance, flowering plant species richness, effective number of species of flowers or community composition.

Our results suggest that ground-nesting bees prefer to nest in burned patches of remnant tallgrass prairies and highlight opportunities for future research to better understand bee nesting ecology in response to prairie management.

Keywords: emergence tents; emergence traps; prairie management; prescribed burn; remnant prairie

Citation

Brokaw, Julia, Zachary M. Portman, Bethanne Bruninga‐Socolar, and Daniel P. Cariveau. "Prescribed fire increases the number of ground‐nesting bee nests in tallgrass prairie remnants." Insect Conservation and Diversity (2023).

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“Thicketized oak woodlands reduce groundwater recharge” @prairiefiresci @oakfirescience

“Thicketized oak woodlands reduce groundwater recharge”

Article available online Dec. 2022 in Science of the Total Environment. Access the article via the permanent web address (DOI). (https://doi.org/10.1016/j.scitotenv.2022.160811)

Highlights

• Woodland thicketization is a common phenomenon across the oak savannas (USA) with possible implications for groundwater recharge.
• Chloride and soil moisture were measured under different vegetation covers in a woodland pasture in Post Oak Savanna, Texas.
• Both sets of measurements showed substantial deep drainage in the open areas and no deep drainage in the thicketized woodland.
• Our results strongly suggest that thicketization is greatly reducing recharge in the Post Oak Savannas and the underlying Carrizo-Wilcox aquifer.

Abstract

Woodlands and pastures across the Post Oak Savannas (POS) in Texas have been undergoing thicketization over the last century via encroachment by understory shrubs such as Yaupon (Ilex decidua, Ilex vomitoria) and expansion of eastern redcedar (Juniperus virginiana). Because a large part of POS overlies the Carrizo-Wilcox (CW) aquifer – the third most important aquifer in Texas, there is a strong incentive to identify opportunities to increase groundwater recharge through land management.

The purpose of this research is to evaluate the influence of thicketization of post oak (Quercus stellata) stands on deep drainage (DD) in POS. We achieved this by, a) applying chloride mass balance on soil cores, and b) simultaneously monitoring soil moisture in a woodland pasture setting in POS. Four sites representing different vegetation covers were identified for sampling: 1) a thicketized oak woodland paired with an adjacent open site, 2) a woodland mosaic, 3) a pasture and 4) a pine-oak stand paired with an adjacent open site. A total of 24 soil cores to the depth of 260 cm were collected and (soil) pore water chloride concentrations at multiple depths were measured. Soil moisture was monitored at 21 locations, to the depth of 140–260 cm using a neutron moisture meter.

Negligible DD was estimated in the thicketized woodland, whereas most open locations recorded 3–18 cm/year and the woodland mosaic 0–1 cm of DD. Soil moisture data, collected from Jul-2020 to Jun-2021 also suggested higher deep drainage fluxes under open areas – with occurrence of sub-surface saturation only under the open areas and never under the woodlands. These results suggest that the thicketization in oak savannas is substantially reducing groundwater recharge.

Given the extent of thicketized oak savannas across United States, this could be impacting water budgets and groundwater recharge rates on regional scales.

Keywords: Woody plant encroachment; Ecohydrology; Chloride mass balance; Carrizo–Wilcox aquifer; Thicketization

Citation

Basant, Shishir, Bradford P. Wilcox, Chelsea Parada, Briana M. Wyatt, and Brent D. Newman. "Thicketized oak woodlands reduce groundwater recharge." Science of The Total Environment 862 (2023): 160811.

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“Impact of Eastern Redcedar encroachment on water resources in the Nebraska Sandhills” #rxfire #nitrate #hydrology @gpfirescience @prairiefiresci

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

This article was published Oct. 24, 2022, in Science of the Total Environment. Access the article via the permanent web address (DOI). (https://doi.org/10.1016/j.scitotenv.2022.159696)

Highlights

• Streamflow reduced by 46 % compared to historical flows for 100 % redcedar encroachment.
• Encroachment increases atrazine by 4 to 30 % compared to historical concentrations.
• Nitrate increases from 0.89–0.94 mg/L to 0.98–1.02 mg/L for 100 % encroachment.

Abstract

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.

Keywords: Soil and Water Assessment Tool; Loup River Platte River; Atrazine; Baseflow-dominated watershed

Citation

Kishawi, Yaser, Aaron R. Mittelstet, Troy E. Gilmore, Dirac Twidwell, Tirthankar Roy, and Nawaraj Shrestha. "Impact of Eastern Redcedar encroachment on water resources in the Nebraska Sandhills." Science of The Total Environment 858 (2023): 159696.

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“Trajectories and state changes of a grassland stream and riparian zone after a decade of woody vegetation removal”

“Trajectories and state changes of a grassland stream and riparian zone after a decade of woody vegetation removal”

Published online March 2, 2023, in Ecological Applications. Access online via the permanent web address (DOI). (https://doi.org/10.1002/eap.2830)

Abstract

Riparian zones and the streams they border provide vital habitat for organisms, water quality protection, and other important ecosystem services. These areas are under pressures from local (land use/ land cover change) to global (climate change) processes. Woody vegetation is expanding in grassland riparian zones worldwide.

Here, we report on a decade-long watershed-scale mechanical removal of woody riparian vegetation along 4.5 km of stream channel in a before-after control impact experiment. Prior to this removal, woody plants had expanded into grassy riparian areas, which was associated with a decline in streamflow, loss of grassy plant species, and other ecosystem-scale impacts.

We confirmed some expected responses, including rapid increases in stream nutrients and sediments, disappearance of stream mosses, and decreased organic inputs to streams via riparian leaves. We were surprised that nutrient and sediment increases were transient for three years, that there was no recovery of stream discharge, and that areas with woody removal did not shift back to a grassland state, even when re-seeded with grassland species. Rapid expansion of shrubs (Cornus drummondii, Prunus americana) in the areas where trees were removed allowed woody vegetation to remain dominant despite repeating the cutting every two years. Our results suggest woody expansion can fundamentally alter terrestrial and aquatic habitat connections in grasslands resulting in inexorable movement toward a new ecosystem state. Human pressures such as climate change, atmospheric CO2 increases, and elevated atmospheric nitrogen deposition could continue to push the ecosystem along a trajectory that is difficult to change.

Our results suggest that predicting relationships between riparian zones and the streams they border could be difficult in the face of global change in all biomes, even in well-studied sites.

Keywords: alternative states; nutrients; riparian zone; stream discharge; thresholds; water quality; woody vegetation

Citation

Dodds, Walter K., Zak Ratajczak, Rachel M. Keen, Jesse B. Nippert, Bartosz Grudzinski, Allison Veach, Jeffery H. Taylor, and Amanda Kuhl. "Trajectories and state changes of a grassland stream and riparian zone after a decade of woody vegetation removal." Ecological Applications (2023): e2830.

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“Heterogeneity of Kentucky Bluegrass (Poa pratensis L.) Seed Germination After Controlled Burning” @prairiefiresci @gpfirescience @rangelands

“Heterogeneity of Kentucky Bluegrass (Poa pratensis L.) Seed Germination After Controlled Burning”

Available online May 7, 2022 in Rangeland Ecology and Management. Access the article via the permanent web address (DOI). (https://doi.org/10.1016/j.rama.2022.04.001)

Abstract

Prescribed burning is sometimes advocated as a means for controlling Kentucky bluegrass (POPR) in invaded grazing lands. However, little is known about the effects of fire on POPR seed survival.

We exposed seeds of POPR (c.v. Kenblue), placed in shallow metal dishes, at ground level to prescribed burns while monitoring temperature at the soil surface and at 10 cm above ground with thermocouples and assessed subsequent seed germinability.

Maximum surface temperatures during the test burns averaged 271°C ± 23°C but varied widely (range 41°C–509°C) while maximum temperature at 10 cm above ground was slightly higher (301°C ± 25°C). Burning inhibited seed survival or the ability to germinate (Kolmogorov-Smirnov P < .0001). Germination of the POPR seeds in the control dishes averaged 93% ± 1%. Average germination for burned locations was 37% ± 7% and was distributed bimodally; it was absent or strongly inhibited in 59% of the samples but much less affected (≥ 60% normal germination) in the remaining 41% of locations. Germination success was similar in burned plots previously managed with both grazing and fire (35% ± 10%) or previously managed by fire alone (38% ± 11%), but it was significantly and inversely correlated to maximum surface temperature during the burn (Spearman r = −0.49, P < 0.005). However, we observed a binary pattern of high and low seed germination response across the entire gradient of recorded surface temperatures, including instances of highly disparate values for seed survival in samples located within 60 cm of each other.

Such extreme variability may result from unburned or superficially affected safe sites that originate from heterogeneity of fire impacts.This study suggests prescribed burning can kill POPR seeds near the soil surface, especially those located in standing litter and dry thatch. However, some seeds under these layers and closer to the mineral soil surface may be less impacted.

Citation

Halvorson, Jonathan J., David Toledo, and John R. Hendrickson. "Heterogeneity of Kentucky Bluegrass (Poa pratensis L.) Seed Germination After Controlled Burning." Rangeland Ecology & Management 83 (2022): 112-116.

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“Cattle Graze Central US Milkweeds at Least as Much as Grasses, Even Under Patch-Burn-Grazing Management” @gpfirescience @rangelands @helzerprairie

“Cattle Graze Central US Milkweeds at Least as Much as Grasses, Even Under Patch-Burn-Grazing Management”

This article was published Jan. 26, 2023 in Rangeland Ecology and Management. Access the article via the permanent web address (DOI). (https://doi.org/10.1016/j.rama.2023.01.001)

Abstract

Most researchers assume cattle avoid milkweeds due to toxic compounds. However, observations suggest cattle graze common milkweed (Asclepias syriaca L.), an important summer host plant for monarch butterflies (Danaus plexippus L.) east of the Rocky Mountains, as well as showy milkweed (Asclepias speciosa Torr.). This directly relates to efforts to add over 1 billion stems of milkweed for monarch butterfly conservation.

We sampled whether cattle regularly graze common/showy milkweed in a central Nebraska restored prairie patch-burn-grazing system with patches burned in the year of the main study (2018) or previous years (2017–2016). We also sampled burned control grasslands without livestock. This sampling therefore compared three different types of burn-graze management. Cow-calf pairs were put onto the grasslands in April, and we sampled every 2 wk through September.

We found that wild grazers (e.g., deer) were not grazing common/showy milkweed stems in control grasslands, whereas by August > 73% of stems had been grazed in the patch-burn-grazed grasslands—with no noticeable negative effects on cattle. Also, cattle grazing of common/showy milkweed did not differ significantly in different patches, even though big bluestem grass (Andropogon gerardii Vitman) was grazed significantly more in patches burned in 2018. Finally, milkweed abundance in control grasslands ranged from 34- to 185-fold higher than the average milkweed abundance in patch-burn-grazed grasslands.

These results suggest that cattle regularly graze common/showy milkweed and that patch-burn-grazing does not increase milkweed abundance when cattle begin grazing in April. The good news of these results is that cattle safely grazed low amounts of common/showy milkweed, suggesting control efforts for these milkweeds are often unnecessary. Future work should examine how to increase milkweed abundance without affecting cattle weight gain, possibly by deferring grazing in some areas during critical milkweed growth periods.

Citation

Dickson, Timothy L., Brittany Poynor, and Christopher J. Helzer. "Cattle Graze Central US Milkweeds at Least as Much as Grasses, Even Under Patch-Burn-Grazing Management." Rangeland Ecology & Management 87 (2023): 158-166.

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“Pre-Columbian red pine (Pinus resinosa Ait.) fire regimes of north-central Pennsylvania, USA” @prairiefiresci @oakfirescience @usfs_nrs

“Pre-Columbian red pine (Pinus resinosa Ait.) fire regimes of north-central Pennsylvania, USA”

Published June 28, 2022 in Fire Ecology. Access the article via the USDA Treesearch database. (https://www.nrs.fs.usda.gov/pubs/64570)

Abstract

Background

Fire-dependent vegetation communities in the northeastern USA have undergone significant transitions since social and ecological disruptions associated with Euro-American colonization of North America. There is much interest, though little information available, about historical fire regimes of fire-adapted vegetation communities in the northeastern USA in pre-Columbian times (i.e., pre-1492 CE).

We intensively investigated a red pine (Pinus resinosa Ait.)—oak (Quercus spp.) forested landscape in north-central Pennsylvania, USA, for exceptionally old red pine remnants (stumps, snags) where previous research had suggested the potential to develop fire-scar and tree-ring chronologies which extend to time periods prior to 1492.

Results

Tree-ring and fire-scar chronologies recovered from red pine trees extend back to 1370 and 1402, respectively. Red pine trees were broadly distributed across this landscape (34.4 km2 area) prior to 1492, and frequent fire (i.e., mean fire return intervals of 4.1 years at landscape scale, 9.7–11.7 years at smaller spatial scales (0.5–7.1 km2)) was observed in the time period prior to sustained contact between Indigenous peoples and Euro-American colonizers circa 1609.

Conclusions

This study resulted in the longest fire-scar record in eastern North America and offers unique foundational ecological information regarding pre-Columbian fire regimes of northeastern USA fire-adapted forest communities. Fire scars provide physical evidence that fire was an important ecological component of this landscape before and after 1492 and that the current period of reduced fire activity is unprecedented in the 500 years prior to fire exclusion practices that were widely adopted circa 1915. Beyond fire scars, the spatial and temporal extent of the red pine tree-ring record provides evidence that red pine, a fire-dependent species, was historically a more important component of this landscape than it is today. The conservation of red pine vegetation communities will require incorporating recurring fire into management plans, for the successful regeneration and perpetuation of red pine, and to sustain associated flora and fauna of conservation concern.

Keywords: Fire regimes; Northeastern USA; Pennsylvania; Pre-Columbian; Red pine

Citation

Marschall, Joseph M.; Stambaugh, Michael C.; Abadir, Erin R.; Dey, Daniel C.; Brose, Patrick H.; Bearer, Scott L.; Jones, Benjamin C. 2022. Pre-Columbian red pine (Pinus resinosa Ait.) fire regimes of north-central Pennsylvania, USA. Fire Ecology. 18(1): Article 11. 19 p. https://doi.org/10.1186/s42408-022-00135-6.