Browsing and fire decreases dominance of a resprouting shrub in woody encroached grassland

O’Connor, Robert T.; Taylor, Jeffrey H.; Nippert, Jesse B.

doi:10.1002/ecy.2935

Cited by 59 publications

(44 citation statements)

References 71 publications

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“…However, I found no difference in nonstructural carbohydrates between burned and control trees. Contrastingly, a threefold decrease in total nonstructural carbohydrates (sugars and starches) was found in a resprouting rangeexpanding woody shrub Cornus drummondii after browsing and a prescribed fire in Kansas [3]. In another study, root starch was found to be a key nutrient that limits resprouting ability after fires in two savanna shrubs, Miconia albicans and Clidemia sericea [150].…”

Section: Optimal Partitioning Theorymentioning

confidence: 91%

“…Native species are capable of spreading rapidly into new habitats and niches, and act similarly to invasive species, usually in response to a disturbance of that habitat [1][2][3]. However, invasive species were far more likely than native species to respond to disturbances [2].…”

Section: Introductionmentioning

confidence: 99%

“…In addition to expanding into rangelands, where eastern redcedars reduce the amount of grazing land for cattle and sheep [9,10,44] and browsing for wild ungulates [3], this species causes serious alterations in ecosystem services. For example, reductions in stream run-off and discharge are widespread where eastern redcedar is abundant [15-18, 45, 46].…”

Section: Introductionmentioning

confidence: 99%

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Shade is the most important factor limiting growth of a woody range expander

Ward¹

2020

PLoS ONE

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The expansion of woody plants into grasslands and old fields is often ascribed to fire suppression and heavy grazing, especially by domestic livestock. However, it is also recognized that nutrient availability and interspecific competition with grasses and other woody plants play a role in certain habitats. I examined potential factors causing range- and niche expansion by the eastern redcedar Juniperus virginiana, the most widespread conifer in the eastern United States, in multifactorial experiments in a greenhouse. Historical records suggest that the eastern redcedar is a pioneer forest species, and may be replaced as the forest increases in tree density due to shading. Another possible factor that affects its distribution may be nutrient availability, which is higher in old fields and other disturbed lands than in undisturbed habitats. In its historic range, eastern redcedars are particularly abundant on limestone outcrops, often termed ‘cedar barrens’. However, the higher abundance on limestone could be due to reduced interspecific competition rather than a preference for high pH substrates. I manipulated shade, fertilization, lime, and interspecific competition with a common dominant tree, the post oak Quercus stellata. In a separate experiment, I manipulated fire and grass competition. I measured growth rates (height and diameter) and above- and belowground biomass at the end of both experiments. I also measured total non-structural carbohydrates and nitrogen in these plants. Shade was the most important factor limiting the growth rates and biomass of eastern redcedars. I also found that there were significant declines in nitrogen and non-structural carbohydrates when shaded. These results are consistent with the notion that the eastern redcedar is a pioneer forest species, and that shade is the reason that these redcedars are replaced by other tree species. In the second experiment, I found that a single fire had a negative effect on young trees. There was no significant effect of competition with grass, perhaps because the competitive effect was shading by grasses and not nutrient depletion. Overall, the effects of shade were far more apparent than the effects of fire.

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Section: Optimal Partitioning Theorymentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Shade is the most important factor limiting growth of a woody range expander

Ward¹

2020

PLoS ONE

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“…Persistent shifts in shrub cover were only found in our pixel‐by‐pixel analysis. Resprouting shrub species are generally unresponsive to low‐intensity fires that occur in the absence of browsers in local field‐based studies (O'Connor et al, 2020; Ratajczak et al, 2014), while high‐intensity fire can drive a decrease in shrub cover (Ansley & Jacoby, 1998; Twidwell et al, 2016). Our results likely reflect some of this heterogeneity in fire intensity created by wildfire.…”

Section: Discussionmentioning

confidence: 99%

Resilience to Large, “Catastrophic” Wildfires in North America's Grassland Biome

et al. 2020

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Wildfires are ecosystem‐level drivers of structure and function in many vegetated biomes. While numerous studies have emphasized the benefits of fire to ecosystems, large wildfires have also been associated with the loss of ecosystem services and shifts in vegetation abundance. The size and number of wildfires are increasing across a number of regions, and yet the outcomes of large wildfire on vegetation at large‐scales are still largely unknown. We introduce an exhaustive analysis of wildfire‐scale vegetation response to large wildfires across North America's grassland biome. We use 18 years of a newly released vegetation data set combined with 1,390 geospatial wildfire perimeters and drought data to detect large‐scale vegetation response among multiple vegetation functional groups. We found no evidence of persistent declines in vegetation driven by wildfire at the biome level. All vegetation functional groups exhibited relatively rapid recovery to pre wildfire ranges of variation across the Great Plains ecoregions, with the exception being a persistent decrease in the abundance of trees in the Northwestern Great Plains. Drought intensity magnified immediate vegetation response to wildfire. Persistent declines in vegetation cover were observed at the scale of single pixels (30 m), suggesting that these responses were localized and represent extreme cases within larger wildfires. Our findings echo over a century of research demonstrating a biome resilient to wildfire.

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“…The sparse U. pumila trees on the temperate savanna-like ecosystem have ecological significance because they provide sand stabilization and also resting places for livestock [19]. In recent years, due to various changing conditions, such as climate change and land use change in the course of economic development [20][21][22], there has been severe damage to the U. pumila-dominated temperate savanna-like ecosystem. This damage has led to an increase in the number of shrubs and the densification of woody plant cover as well as outcomes such as decreasing temperate savanna-like ecosystem area, the loss of structural integrity, poor population regeneration, and changing spatial patterns [23,24].…”

Section: Introductionmentioning

confidence: 99%

Does Shrub Encroachment Indicate Ecosystem Degradation? A Perspective Based on the Spatial Patterns of Woody Plants in a Temperate Savanna-Like Ecosystem of Inner Mongolia, China

Jiang

Yang

Shi

et al. 2020

Forests

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Shrub encroachment, i.e., shrub emergence or an increase in woody plant cover, has been widely observed in arid and semiarid grasslands and savannas worldwide since the 2000s. However, until now, there has been a clear division of opinion regarding its ecological implications. One view is that shrub encroachment is an indicator of ecological degradation, and the other is that shrub encroachment is a sign of the restoration of degraded ecosystems. This division leads to completely different judgments about the states and transition phases of shrub-encroached ecosystems, which further affects decisions about their conservation and management. To determine whether ecosystems experiencing shrub encroachment are degrading or are in a postdegraded restoration stage, the spatial distributions and interactions of woody plants after shrub encroachment were investigated in this study. An Ulmus pumila-dominated temperate savanna-like ecosystem with significant shrub encroachment in the Otindag Sandy Land, Inner Mongolia, China, was selected as the research area, and woody plants were surveyed within a 25-hectare (500 × 500 m) plot. Spatial point pattern analysis was employed to analyze the distribution patterns of the woody plants. The results indicated different patterns for U. pumila trees, i.e., a random distribution pattern for old trees (with a diameter at breast height (DBH) of more than 20 cm) and aggregated distribution patterns for medium (5 cm ≤ DBH < 20 cm) and juvenile trees (DBH < 5 cm) at scales of 0–9 and 0–12 m, respectively. For most shrubs, there was significant aggregation at a scale of 0–6 m. However, there were significant negative relationships between old U. pumila trees (DBH ≥ 20 cm) and most shrub species, such as Caragana microphylla and Spiraea aquilegifolia. In contrast, there were positive relationships between juvenile trees (DBH < 5 cm) and most shrub species. These results suggest that, to some extent, shrub encroachment may have disrupted the normal succession pattern in the U. pumila community in this area, and without conservation, the original tree-dominated temperate savanna-like ecosystem may continue to deteriorate and eventually become a shrub-dominated temperate savanna-like ecosystem.

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Browsing and fire decreases dominance of a resprouting shrub in woody encroached grassland

Cited by 59 publications

References 71 publications

Shade is the most important factor limiting growth of a woody range expander

Shade is the most important factor limiting growth of a woody range expander

Resilience to Large, “Catastrophic” Wildfires in North America's Grassland Biome

Does Shrub Encroachment Indicate Ecosystem Degradation? A Perspective Based on the Spatial Patterns of Woody Plants in a Temperate Savanna-Like Ecosystem of Inner Mongolia, China

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