An official website of the United States government
Forest-grassland ecotones are a mosaic of grassland, savanna, and upland forest. As such, landowners may have opportunities to choose to manage their lands for multiple objectives. We estimated the economic returns from managing forest and rangeland in southeastern Oklahoma, USA to produce different combinations of timber, cattle forage, and white-tailed deer (Odocoileus virginianus Zimmermann) browse for a 40-year period. We further conducted a survey to understand landowner perceptions of obstacles to adopting active management that involve timber harvest and prescribed fire. The highest net return was obtained from the treatment with harvested timber that was burned every four years (uneven-aged woodland/forest) because it had the greatest gross return from a combination of timber (46%), cattle forage (42%), and deer browse (11%). The return from this treatment was greater than that for managed for timber only (closed-canopy forest) or prioritizing cattle and deer (savanna). Survey results suggested that landowners were aware of the benefits of active management but that the majority (66%) considered cost a major obstacle in the management of their forest or rangeland. In particular, women forestland owners and older landowners considered cost an obstacle. Our findings advocate integrated timber, cattle, and deer management as the best economic strategy within the forest-grassland ecotone and for targeted outreach and landowner education related to the benefits of active management.
more »
« less
Forage quantity and protein concentration changes across a forest-savanna gradient with management implications for white-tailed deer
White-tailed deer (Odocoileus virginianus) hunting is an important economic activity associated with the management of forests and rangelands in the USA, with over $12.9 billion dollars of related annual expenditures. Reducing tree cover through thinning and prescribed fire both have the potential to increase the quantity and quality of deer forage. We evaluated the long-term impacts of eight different combinations of fire return intervals and tree harvest on forage productivity and protein content of the forage. Based on management regime, study units ranged from savanna to closed-canopy forest. Aboveground net primary production (ANPP) of six functional groups (grass, panicum, forb, legume, woody, sedge) of understory vegetation was measured in October 2019 and 2020 using destructive sampling. Samples for foliar crude protein (CP) concentration were collected in spring, summer, and fall of 2020. Total understory ANPP ranged from 2.9 to 466.3 g m− 2 and was up to 566% greater in savanna systems maintained by frequent fire (return interval of three years or less) than in non-burned forest treatments. Annual burning resulted in ANPP dominated by herbaceous plants composed mostly of firetolerant grasses (e.g., Andropogon gerardii, Schizachyrium scoparium). Longer fire return intervals or no fire resulted in roughly equal ANPP from understory woody and herbaceous species. Crude protein concentrations were up to 45.7% greater in the woodland and forest units than in the savanna units for seven of the eleven species sampled. The greater CP in the forests was most noticeable in the summer when deer needs for quality forage are substantial. Increased protein concentrations of understory species in the forests, but greater ANPP in the savannas indicate that managing for a mix of savanna and woodland could be ideal for balancing forage quantity with increased forage protein.
more »
« less
- Award ID(s):
- 1946093
- PAR ID:
- 10494865
- Publisher / Repository:
- ELSEVIER
- Date Published:
- Journal Name:
- Forest Ecology and Management
- Volume:
- 538
- Issue:
- C
- ISSN:
- 0378-1127
- Page Range / eLocation ID:
- 120987
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract Fire–vegetation feedbacks potentially maintain global savanna and forest distributions. Accordingly, vegetation in savanna and forest ecosystems should have differential responses to fire, but fire response data for herbaceous vegetation have yet to be synthesized across biomes. Here, we examined herbaceous vegetation responses to experimental fire at 30 sites spanning four continents. Across a variety of metrics, herbaceous vegetation increased in abundance where fire was applied, with larger responses to fire in wetter and in cooler and/or less seasonal systems. Compared to forests, savannas were associated with a 4.8 (±0.4) times larger difference in herbaceous vegetation abundance for burned versus unburned plots. In particular, grass cover decreased with fire exclusion in savannas, largely via decreases in C4grass cover, whereas changes in fire frequency had a relatively weak effect on grass cover in forests. These differential responses underscore the importance of fire for maintaining the vegetation structure of savannas and forests.more » « less
-
The future of tropical forests depends on their ability to resist and recover from multiple disturbances. Here, we evaluated how edge effects, experimental fires, extreme droughts, and blowdowns reshaped forest structure, composition, and functional traits over two decades in the Amazon–Cerrado transition. Initially, forests resisted low-intensity fires, but subsequent high-intensity fires during severe droughts sharply increased susceptibility to further disturbances. Along forest edges bordering agriculture, these compound disturbances drove losses of tree species richness, declines in Amazonian forest-specialist species, and shifts toward generalists with broad distributions, indicating increased compositional homogenization (i.e., reduced taxonomic diversity and dominance of generalist species). Once fires ceased, recovery trajectories diverged: Interior forests rapidly regained woody species richness and composition, whereas edge forests recovered more slowly. During postfire recovery, embolism-resistant species (lower P50 values) became more common, yet communities exhibited lower hydraulic safety margins (increased vulnerability to drought). At the same time, generalist species remained abundant, forest-specialist declined, and only a single woody species typical of savanna was established. Although grasses initially colonized fire-altered edges—especially light-demanding exoticAndropogon gayanus—they declined once fires stopped, leaving only small patches of shade-tolerant C3 species. Consequently, we find little evidence that fire-degraded forests transition toward persistent savanna, although recurrent fires or future climatic changes could drive long-lasting degradation or human-derived savannas. Together, these results show that even highly degraded, grass-invaded forests can recover in the absence of new disturbances, but the communities that reassemble remain vulnerable to renewed fire, drought, or windthrow.more » « less
-
Active management such as prescribed fire and thinning can restore savanna and prairie ecosystem to maintain a full suite of ecosystem services and create suitable habitat for wildlife species such as white-tailed deer (Odocoileus virginianus). Active management comes with the cost of management and acceptance of management tools. The south-central transitional ecoregion of the USA, which otherwise was a mixture of forest, savanna, and tallgrass prairie, is increasing in woody plant dominance due to the exclusion of fire and other anthropogenic factors. Deer hunting is a vital source of revenue generation to offset the landowner’s management cost in the region. We studied Oklahoma landowners’ perceptions regarding active and sustainable management of forest and rangeland for deer habitat using two established theories of reasoned action and planned behavior as well as expanded theories adding moral norms. We analyzed mailed survey data using structural equation modeling. We found that subjective norms and perceived behavior control significantly affected deer hunting intention when moral norms were introduced into the model. Attitudes independently significantly affected intentions of deer hunting but have negative relations with the intentions. The study suggested that landowners have positive social pressure and were interested in active management but associated financial burden and risk could be shaping negative attitudes. Keywords Theory of planned behavior ● Theory of reasoned action ● Moral norms ● Prescribed fire ● White-tailed deer (Odocoileus virginianus)more » « less
-
ABSTRACT Forage availability is a key factor regulating large herbivore populations. Global changes in land use and climate may affect the spatiotemporal distribution of forage across the ranges of large herbivores, especially in mountain ecosystems. We test two synergistic hypotheses for how landscape and climate changes from 2001 to 2023 have affected forb and graminoid biomass at the peak of the growing season within and across ecoregions of the eastern slopes of the Rocky Mountains in Alberta, Canada. The successional change hypothesis posits that the encroachment of woody vegetation into previously herbaceous communities has reduced forage biomass. The disturbance hypothesis proposes that abrupt community shifts caused by fire and timber harvesting have increased forage biomass. Using remote sensing, we quantify temporal changes in land cover and disturbances, NDVI greenness and phenology indices, and spring climate. We then used in situ vegetation data to parameterize generalized linear and gradient boosted regression tree models of forb and graminoid biomass to predict annual peak forb and graminoid biomass. Herbaceous land cover declined while shrub and forest area increased, and the percent of annual biomass within herbaceous areas declined from woody encroachment. Disturbance effects varied, with rising forage biomass in conjunction with increased area of logged forests in the foothills ecoregion, while burned areas declined and had a reduced contribution to the percent of annual biomass. Additionally, spring became warmer across the study area and ended earlier in the alpine, suggesting the effects of long‐term climatic shifts may be strongest at higher ecoregions. Disturbance frequency, succession, and climate together shaped forage biomass in space and time. Increased prescribed fire and other ecological restoration actions may be needed to ensure that shifts in forage biomass do not threaten large herbivore persistence in the face of global change.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript
- Journal Article:
- https://doi.org/10.1016/j.foreco.2023.120987
