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This data release includes data and metadata on seedling abundance, composition, and rooting substrate within Hakalau Forest National Wildlife Refuge on Hawaii Island. This study aims to evaluate the role of bryophytes in seedling recruitment and thus forest regeneration in different forest types. We compared bryophyte composition and coverage between tree species (Acacia koa and Metrosideros polymorpha) and forest types (intact forest and restoration forest) and then sampled native woody seedling recruitment in the bryophytes as well as other ground covers, such as leaf litter, bare soil, and exotic grass.
Long-lived desert shrubs exhibit infrequent, episodic recruitment from seed. In spite of this long time scale, selection on life history attributes that affect seedling recruitment should be strong. We studied factors affecting germination phenology and seedling establishment for Coleogyne ramosissima, a dominant shrub species in the ecotone between warm and cold deserts in western North America. We also examined ecotypic differentiation in establishment strategy in response to selection regimes in two contrasting habitats. We followed patterns of dormancy loss, germination, emergence, and survival in reciprocal field experiments at warm winter Mojave Desert and cold winter Colorado Plateau study sites. Seed germination...
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The relationship between vegetation cover and soil seed banks was studied in five different ungulate herbivoreprairie dog treatment combinations at three northern mixed-grass prairie sites in Badlands National Park, South Dakota. There were distinct differences in both the seed bank composition and the aboveground vegetation between the off-prairie dog colony treatments and the on-colony treatments. The three on-colony treatments were similar to each other at all three sites with vegetation dominated by the forbs Dyssodia papposa, Hedeoma spp., Sphaeralcea coccinea, Conyza canadensis, and Plantago patagonica and seed banks dominated by the forbs Verbena bracteata and Dyssodia papposa. The two off-colony treatments...
Categories: Publication; Types: Citation; Tags: Plant Ecology
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In North America, most Artemisia (Asteraceae) shrub species lack the ability to resprout after disturbances that remove aboveground biomass. We studied the response of one of the few resprouting Artemisia shrubs, Artemisia filifolia (sand sagebrush), to the effects of prescribed fires. We collected data on A. filifolia density and structural characteristics (height, canopy area, and canopy volume) in an A. filifolia shrubland in the southern Great Plains of North America. Our study sites included areas that had not been treated with prescribed fire, areas that had been treated with only one prescribed fire within the previous 5 years, and areas that had been treated with two prescribed fires within the previous...
Categories: Publication; Types: Citation; Tags: Plant Ecology
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Ecosystems in the eastern United States that were shaped by fire over thousands of years of anthropogenic burning recently have been subjected to fire suppression resulting in significant changes in vegetation composition and structure and encroachment by invasive species. Renewed interest in use of fire to manage such ecosystems will require knowledge of effects of fire regime on vegetation. We studied the effects of one aspect of the fire regime, fire frequency, on biomass, cover and diversity of understory vegetation in upland oak forests prescribe-burned for 20 years at different frequencies ranging from zero to five fires per decade. Overstory canopy closure ranged from 88 to 96% and was not affected by fire...
Categories: Publication; Types: Citation; Tags: Plant Ecology
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Rare plants are often associated with distinctive soil types, and understanding why endemic species occur in unique environments is fundamental for their management. At Ash Meadows National Wildlife Refuge in southern Nevada, USA, we evaluated whether the limited distribution of endangered Amargosa niterwort (Nitrophila mohavensis) is explained by this species’ tolerance of saline soils on salt-encrusted mud flats compared with the broadly distributed desert saltgrass (Distichlis spicata var. stricta). We simultaneously explored whether niterwort distribution is restricted from expanding due to interspecific competition with saltgrass. Surface soils collected throughout niterwort’s range were unexpectedly less saline...
Categories: Publication; Types: Citation; Tags: Plant Ecology
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Reforestation of bottomland hardwood sites in the southeastern United States has markedly increased in recent years due, in part, to financial incentives provided by conservation programs. Currently > 250,000 ha of marginal farmland have been returned to hardwood forests. I observed establishment of trees and shrubs on 205 reforested bottomlands: 133 sites were planted primarily with oak species (Quercus spp.), 60 sites were planted with pulpwood producing species (Populus deltoides, Liquidambar styraciflua, or Platanus occidentalis), and 12 sites were not planted (i.e., passive regeneration). Although oak sites were planted with more species, sites planted with pulpwood species were more rapidly colonized by additional...
Categories: Publication; Types: Citation; Tags: Plant Ecology
Broom snakeweed (snakeweed) is an aggressive native range-weed found throughout arid and semiarid areas of the western United States, that increases following disturbances such as overgrazing, drought, or wildfire. Ecologically based strategies that include controlling snakeweed and reestablishing desirable herbaceous species are needed to restore productivity and diversity to invaded areas. The objective of this study was to compare the ability of selected introduced and native grass species and prostrate kochia (kochia) to prevent reinvasion of snakeweed, downy brome, and annual forbs following control. This field study was replicated at two sites (Howell and Nephi, Utah) within the sagebrush-steppe biome. Snakeweed...
Invasive exotic weeds pose one of the earth's most pressing environmental problems. Although many invaders completely eliminate native plant species from some communities, ecologists know little about the mechanisms by which these exotics competitively exclude other species. Mycorrhizal fungi radically alter competitive interactions between plants within natural communities, and a recent study has shown that arbuscular mycorrhizal (AM) fungi provide a substantial competitive advantage to spotted knapweed, Centaurea maculosa, a noxious perennial plant that has spread throughout much of the native prairie in the northwestern U.S. Here we present evidence that this advantage is potentially due to mycorrhizally mediated...
This data release includes data and metadata on soil carbon (C) and nitrogen (N) in sites where litter was experimentally manipulated. All sites were within Hakalau Forest National Wildlife Refuge on Hawaii Island. Broadly, this study looked at the ability to alter soil nitrogen cycling, exotic grass biomass and native outplant survival with large quantities of Metrosideros polymorpha litter in a forest dominated by Acacia koa.
This data release includes data and metadata on a large-scale seed addition and grass removal experiment that varied both seed rain and grass cover. All sites were within Hakalau Forest National Wildlife Refuge on Hawaii Island. Broadly, this study asks what thresholds of seed rain and native and exotic plant cover are needed for passive forest regeneration. Specifically this data decribes the percent cover of grass over time in plots where we experimantally added varying levels of seed rain and/or manipulated grass biomass manually.
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Seed bank densities respond to factors across local to landscape scales, and therefore, knowledge of these responses may be necessary in forecasting the effects of climate change on the regeneration of species. This study relates the seed bank densities of species of Taxodium distichum swamps to local water regime and regional climate factors at five latitudes across the Mississippi River Alluvial Valley from southern Illinois to Louisiana. In an outdoor nursery setting, the seed banks of twenty-five swamps were exposed to non-flooded (freely drained) or flooded treatments, and the number and species of seeds germinating were recorded from each swamp during one growing season. Based on ANOVA analysis, the majority...
Categories: Publication; Types: Citation; Tags: Plant Ecology
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Woody vegetation is distributed patchily in many arid and semi-arid ecosystems, where it is often associated with elevated nitrogen (N) pools and availability in islands of fertility. We measured N availability and δ15N in paired blue-oak versus annual grass dominated patches to characterize the causes and consequences of spatial variation in N dynamics of grassland-savanna in Sequoia-Kings Canyon National Park. We found significantly greater surface soil N pools (0–20 cm) in oak patches compared to adjacent grass areas across a 700 m elevation gradient from foothills to the savanna-forest boundary. N accumulation under oaks was associated with a 0.6‰ depletion in soil δ15N relative to grass patches. Results from...
Categories: Publication; Types: Citation; Tags: Plant Ecology
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The paper compares distributions of native weedy species and exotic species with respect to three kinds of disturbance, roads, trails, and prairie dog towns. Data were collected at the north and south units of Theodore Roosevelt National Park and at Wind Cave National Park. The paper concludes that many exotic species differ substantially from native weeds in their exploitation of disturbance. It is thus not useful to manage exotics as if they were just another weed.
Categories: Publication; Types: Citation; Tags: Plant Ecology
For much of the western USA, precipitation occurs in pulses, the nature of which determine soil water potential and plant physiological performance. This research utilized three experiments to examine the sensitivity of photosynthesis and water relations for two widespread Great Basin Desert shrub species, Artemisia tridentata (which has both deep and shallow roots) and Purshia tridentata (which reportedly has only deep roots), to (1) variation in pulse magnitude size, (2) the kinetics of responses to pulses, and (3) the relationship between pulse-size and antecedent soil water content. At the study site in the southwestern Great Basin Desert, USA, summer rainfall exhibits a greater frequency of larger-sized events,...
This data release includes data and metadata for native outplant growth rates for an experiment that added large quantities of woody litter to a restoration forest in an attempt to lower soil nitrogen and exotic grass biomass. All sites were within Hakalau Forest National Wildlife Refuge on Hawaii Island. Broadly, this study looked at the ability to alter soil nitrogen cycling, exotic grass biomass and native outplant survival and growth with large quantities of Metrosideros polymorpha litter in a forest dominated by Acacia koa.
This data release includes data and metadata on bird-mediated and passive seed rain for sites selected to have a range of understory cover under canopy trees (Metrosideros polymorpha and Acacia koa). All sites were within Hakalau Forest National Wildlife Refuge on Hawaii Island. Broadly, this study asks what thresholds of seed rain and native and exotic plant cover are needed for passive forest regeneration. Quantifying natural seed rain rates in different habitat types was needed to better understand how these thresholds function.
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Aridity is an important environmental filter in the assembly of plant communities worldwide. The extent to which root traits mediate responses to aridity, and how they are coordinated with leaf traits, remains unclear. Here, we measured variation in root tissue density (RTD), specific root length (SRL), specific leaf area (SLA), and seed size within and among thirty perennial grass communities distributed along an aridity gradient spanning 190–540 mm of climatic water deficit (potential minus actual evapotranspiration). We tested the hypotheses that traits exhibited coordinated variation (1) among species, as well as (2) among communities varying in aridity, and (3) functional diversity within communities declines...
Categories: Publication; Types: Citation; Tags: Plant Ecology
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Article for outlet: Plant Ecology. Abstract: Big sagebrush (Artemisia tridentata Nutt.) plant communities are widespread non-forested drylands in western North American and similar to all shrub steppe ecosystems world-wide are composed of a shrub overstory layer and a forb and graminoid understory layer. Forbs account for the majority of plant species diversity in big sagebrush plant communities and are important for ecosystem function. Few studies have explored the geographic patterns of forb species richness and composition and their relationships with environmental variables in these communities. Our objectives were to examine the small and large-scale spatial patterns in forb species richness and composition...
Categories: Publication; Types: Citation; Tags: Plant Ecology


map background search result map search result map Imprint of oaks on nitrogen availability and δ<sup>15</sup>N in California grassland-savanna: A case of enhanced N inputs? Plant seedling composition, abundance and substrate data Hakalau Forest NWR outplant growth Hakalau Forest NWR soil carbon and nitrogen data Mean grass cover in grass removal, seed addition experiment, Hakalau Forest NWR Seed rain in sampling plots, Hakalau Forest NWR Plant seedling composition, abundance and substrate data Hakalau Forest NWR outplant growth Hakalau Forest NWR soil carbon and nitrogen data Mean grass cover in grass removal, seed addition experiment, Hakalau Forest NWR Seed rain in sampling plots, Hakalau Forest NWR Imprint of oaks on nitrogen availability and δ<sup>15</sup>N in California grassland-savanna: A case of enhanced N inputs?