Unburned Tallgrass Prairie Research Articles

Populations of Small Mammals, Tallgrass Prairie and Prescribed Fire: A Fire-Reversal Experiment

We sampled small mammals in burned and unburned tallgrass prairie by using three sites in each of two contiguous ungrazed experimental fire-reversal treatments during 1999-2010. One of the experimental treatments (001A to R20A) had been burned in spring for >20 years and then was switched to an unburned research treatment after the spring fire in 2000. In contrast, the other treatment (020A to R01A) had been left unburned for 20 of 29 years before it was switched to an annually burned treatment beginning with the prescribed fire in spring 2001. Overall, we recorded 11 species of rodents and two of shrews for a total of 2,444 individuals. The white-footed mouse (Peromyscus leucopus) was the most abundant species followed by the hispid cotton rat (Sigmodon hispidus) and deer mouse (P. maniculatus). Of the seven common species (>25 individuals), six were strongly associated with one of the treatments, and several species showed positive associations with some part of the landscape within each treatment. Furthermore, white-footed mice, deer mice, prairie voles (Microtus ochrogaster), western harvest mice (Reithrodontomys megalotis) and Elliot's short-tailed shrews (Blarina hylophaga) showed significant temporal patterns of abundance in either R01A or R20A in one or both seasons (autumn or spring). Our study also supports a very important conservation message. That is, the white-footed mouse (a woodland species) and the hispid cotton rat (a colonizing species) were more numerically dominant than the most common rodent, the deer mouse, (a native prairie species) throughout the 10-year study. These observations demonstrate that areas not burned frequently allow encroachment by shrubs and then trees, which subsequently allow the white-footed mouse and hispid cotton rat to expand into these areas. Conversely, the stoppage of frequent fires ultimately degrades the mosaic of prairie habitats for native prairie small mammals [such as the deer mouse, prairie vole and western and plains harvest mice (R. montanus)] and these species move out as shrubs and trees become common. Visual observations indicate that the latter (degradation of native tallgrass prairie) occurs much more rapidly (potentially within a decade) than the restoration of native tallgrass prairie by the elimination of shrubs and trees by annual burning (potentially 50 or more years).

An Analysis of Malaise-Trap Effectiveness in Assessing Robber Fly (Diptera: Asilidae) Species Richness

Abstract Little quantitative information is available on the effectiveness of Malaise traps in estimating insect species richness. I used the Chao1 nonparametric species richness estimator to evaluate the effectiveness of Malaise traps in assessing species richness of robber flies in west-central Illinois burned and unburned deciduous forest and tallgrass prairie habitats. Two of 12 traps yielded asymptotic species richness values, with remaining traps requiring fold increases ranging from 3.1 to 20.9 to reach asymptotic richness. Overall, observed species richness was over 85% of estimated species richness, but a 3.9-fold sample-size increase would have been required to reach asymptotic species richness. For individual habitats, estimated fold increases in sample size ranging from 1.9 to 9.7 would have been needed to reach asymptotic species richness. These results show that Malaise traps are effective in sampling robber flies, but asymptotic species richness would be difficult to achieve. Lower target c...

Temporal burn scar evolution in tallgrass prairie based on field spectroscopy

In situ field spectroscopy samples were used to simulate several Moderate Resolution Imaging Spectroradiometer (MODIS) bands and indices commonly used for burned area detection. Each band or index was tested for its ability to differentiate between burned and unburned tallgrass prairie during several time periods from spring (when burning took place) to late summer (peak biomass) with three analysis of variance tests. The normalized difference vegetation index (NDVI), global environmental monitoring index (GEMI), global environmental monitoring index – burn scar (GEMI-B), and normalized burn ratio (NBR) indices, as well as MODIS band 7 (longwave mid-infrared; LWMIR), showed virtually no promise for differentiating burned from unburned areas for more than several days after the burn. Others, including the burned area index (BAI), Mid-infrared burn index (MIRBI), and MODIS bands 3 (red), 4 (near-infrared; NIR), 5 (longwave near-infrared; LWNIR), and 6 (shortwave mid-infrared; SWMIR) were able to differentiate between burned and unburned areas well into the growing season – in some cases, even through its entire length. The performance of particular bands and indices often depended on grazing, vegetation phenology, ash/char/soil reflectance, and factors that influenced pre-burn biomass.

Responses of plant and bird communities to prescribed burning in tallgrass prairies

Historic losses and fragmentation of tallgrass prairie habitat to agriculture and urban development have led to declines in diversity and abundance of plants and birds associated with such habitat. Prescribed burning is a management strategy that has potential for restoring and rejuvenating prairies in fragmented landscapes, and through such restoration, might create habitat for birds dependent upon prairies. To provide improved data for management decision-making regarding the use of prescribed fire in tallgrass prairies, we compared responses of plant and bird communities on five burned and five unburned tallgrass prairie fragments at the DeSoto National Wildlife Refuge, Iowa, USA, from 1995 to 1997. Overall species richness and diversity were unaffected by burning, but individual species of plants and birds were affected by year-treatment interactions, including northern bobwhite (Colinus virginianus) and ring-necked pheasant (Phasianus colchicus), which showed time-delayed increases in density on burned sites. Analyses of species/area relationships indicated that, collectively, many small sites did make significant contributions to plant biodiversity at landscape levels, supporting the overall conservation value of prairie fragments. In contrast, most birds species were present on larger sites. Thus, higher biodiversity in bird communities which contain area-sensitive species might require larger sites able to support larger, more stable populations, greater habitat heterogeneity, and greater opportunity for niche separation.

Life History, Secondary Production, and Ecosystem Significance of Acridid Grasshoppers in Annually Burned and Unburned Tallgrass Prairie

Secondary production of the acridid community on Konza Prairie Biological Station, Kansas, was estimated to evaluate its significance to energy and nutrient cycling in annually burned and long-term unburned tallgrass prairie. A drop-trap and vacuum device were used to sample acridids on three watersheds in both the burned and unburned prairies during the 1998 and 1999 growing seasons. Production of common species was estimated using the instantaneous growth method, and consumption and egestion were estimated using ecological efficiencies. Total acridid abundance, biomass, and production estimates showed a trend of higher values on burned than on unburned watersheds during both years with significantly higher biomass and production on burned watersheds during 1998 (P < 0.05). Higher biomass and production on burned watersheds was primarily a result of higher values for graminivorous taxa. Forb-feeder and grass-feeder production was more similar on unburned than on burned watersheds, although responses of individual species varied greatly between the two watershed types and years. Grass-feeders and forb-feeders consumed an estimated 0.4-4.7 g ash-free dry mass (AFDM) m - 2 yr -1 of grass and 0.7-2.1 g AFDM m -2 yr -1 of forbs, respectively, depending on watershed type and year. Results indicate that acridids are important in nitrogen cycling. However, their relative importance to energy and nutrient cycling in tallgrass prairie varies with plant responses to burning and may be influenced by ungulate grazing.

Vegetation responses to different spatial patterns of soil disturbance in burned and unburned tallgrass prairie

Pocket gopher (Geomyidae) disturbances are created in spatiallypredictable patterns. This may influence resource heterogeneity and affectgrassland vegetation in a unique manner. We attempt to determine the extent towhich density and spatial pattern of soil disturbances influence tallgrassprairie plant community structure and determine how these disturbances interactwith fire. To investigate the effects of explicit disturbance patterns we createdsimulated pocket gopher burrows and mounds in various spatial patterns.Simulated burrows were drilled into the soil at different densities inreplicated plots of burned and unburned prairie. Separate plots of simulatedmounds were created in burned and unburned prairie at low, medium, or high mounddensities in clumped, uniform, or random spatial dispersions. In both burned and unburned plots, increased burrow density decreasedgraminoid biomass and increased forb biomass. Total-plant and graminoid biomasswere higher in burned than unburned plots while forb biomass was higher inunburned plots. Total-plant species richness was not significantly affected byburrow density or burning treatments, but graminoid species richness increasedin unburned plots and forb species richness increased in burned plots. Plant species richness was temporarily reduced directly on mounddisturbances compared to undisturbed prairie. Over time and at larger samplingscales, the interaction of fire and mound disturbance patterns significantlyaffected total-plant and graminoid species richness. The principal effect inburned and unburned prairie was decreased total-plant and graminoid speciesrichness with increased mound disturbance intensity. Although species richness at small patch scales was not increased by anyintensity of disturbance and species composition was not altered by theestablishment of a unique guild of disturbance colonizing plants, our studyrevealed that interactions between soil disturbances and fire alter the plantcommunity dominance structure of North American tallgrass prairie primarily viachanges to graminoids. Moreover, these effects become increasingly pronouncedover time and at larger spatial sampling scales.

Seasonality of finely-resolved spatial structure of NDVI and its component reflectances in tallgrass prairie

Grass canopies exhibit distinct seasonality in reflectance and spatial patterns in reflectance result from landscape heterogeneity. To investigate the spatial structure of NDVI and its two component reflectances at fine resolution in burned and unburned tallgrass prairie, we use range and relative nugget effect two indicators of spatial structure derived from semivariograms. Results show that spatial dependence of the three spectral measures are similar in the early season when the litter layer has been removed by burning and again in the later season when the canopy is senescent. However, as the canopy develops, the spatial dependence of NDVI deviates from that of its component reflectances. In the unburned canopy, red reflectance appears to strongly influence the spatial pattern of NDVI. In the burned canopy, neither component reflectance strictly determines the spatial pattern of NDVI. Maximum divergence in spatial pattern between NDVI and its components coincides with minimum available moisture, suggesting a relation between moisture stress and spatio-spectral heterogeneity.

Fire and topographic effects on decomposition rates and N dynamics of buried wood in tallgrass prairie

Decay rates and N dynamics of wood in soils of annually burned and unburned tallgrass prairie were measured over a 3-y period. Wooden dowels were placed at upland, mid-slope and lowland sites in two annually burned and two unburned watersheds. After 3 y, an average of only 15% of initial wood mass remained in burned watersheds, while 34% remained in unburned watersheds. Topographic position also significantly affected decay rates, with dowels decaying faster in the shallow-soil, upland sites and slope sites than in the deep-soil, lowland sites. This pattern is opposite of that generally observed for plant productivity (i.e. greater at lowland sites compared to uplands), and suggests that the controls of belowground decomposition and plant productivity are dissimilar. Dowels in both burned and unburned watersheds showed significant increases in N concentration over 3 y. Topographic position did not affect N concentration in the residual dowel material. Burn treatment, however, did affect N concentration, with dowels decomposing in burned watersheds having a higher average N concentration (0.5% after 3 y exposure) than dowels in unburned watersheds (0.43%). Relatively rapid decay rates resulted in net release of N, despite increased N concentration in the residual material. Faster net N release on the annually burned watershed was due to faster mass loss, since there were no differences in the rate of increase in N concentration per unit mass lost. Surface soil temperatures on burned prairie following spring fire usually exceed those on unburned prairie. However, average monthly summer soil temperatures (May–August) at a 10 cm depth in burned and unburned plots during the study were not statistically different and could not explain decay rate differences. Additionally, one of our unburned watersheds was accidentally burned during the first year of the study. Surprisingly, there were no significant differences in rates of wood decay between that watershed and the other unburned watershed. This suggests that indirect effects of annual fire (i.e. changes in the composition of soil flora and fauna) may override the short-term effects of fire (i.e. changes in soil temperature and moisture) on belowground decomposition in tallgrass prairie.

Investigator Visitation and Predation Rates on Bird Nests in Burned and Unburned Tallgrass Prairie in Oklahoma: An Experimental Study

Investigator Visitation and Predation Rates on Bird Nests in Burned and Unburned Tallgrass Prairie in Oklahoma: An Experimental Study

Water Relations of Juniperus virginiana and Andropogon Gerardii in an Unburned Tallgrass Prairie Watershed

Water Relations of Juniperus virginiana and Andropogon Gerardii in an Unburned Tallgrass Prairie Watershed

Fire and Grazing in the Tallgrass Prairie: Contingent Effects on Nitrogen Budgets

Fire and grazing occur together in many of the world's grasslands, but their effects on nutrient cycling have usually been studied as if they acted separately. We hypothesized that grazing by large herbivores results in conservation of nitrogen that would otherwise be lost from burned grasslands. We tested this hypothesis in a series of experiments on burned and unburned tallgrass prairie grazed by cattle. We manipulated grazing using exclosures and mowing. Combustion losses of N from ungrazed plots (1.8 g°m—2°yr—1) burned in the spring were double those from similarly burned, grazed plots (0.9 g°m—2°yr—1). These losses represented about half of the preburn, aboveground stocks of N. The magnitude of N loss was proportional to the standing crop biomass available for combustion. Fire temperatures and energy release were reduced by grazing. We used mowing to simulate locally heavy grazing in patches. In the absence of burning, mowing patches increased the likelihood that a patch would be regrazed and caused persistent reductions in the residual biomass remaining in a patch at the end of the growing season. Mowing did not influence patch utilization or residual biomass when pastures were burned. Thus, the effects of fire on grassland N budgets were modified by grazing, and the effects of grazing on the patch structure of grasslands were modified by fire. We conclude that accurately predicting volatile losses of nutrients from grassland ecosystems resulting from biomass burning may depend on understanding effects of grazing.

Net carbon dioxide exchange in canopies of burned and unburned tallgrass prairie

Net carbon dioxide exchange (NCE) rates were measured in a tallgrass prairie, a grassland with high productivity, to determine photosynthetic rates of the canopy. Canopy measurements were made in large, plexiglass chambers (1.21 m long; 0.91 m wide; 1.40 m tall) placed on burned and unburned areas of the prairie. The NCE rates of the canopy were compared with those of individual leaves ofAndropogon gerardii Vitman (big bluestem). In addition, CO2 flux from the soil was quantified and compared with net photosynthetic flux. The canopy NCE rates were generally lower than those made on individual leaves. In mid-summer (11 July 1987), the maximum canopy NCE rates were 55% and 64% of those measured on individual leaves in burned and unburned treatments, respectively. Canopy NCE rates were lower than individual-leaf NCE rates for two reasons. First, the individualleaf measurements were made on young, unshaded, healthy leaves, while the canopy measurements were made on all types of leaves including senescing, shaded, and damaged leaves. Second, soil CO2 flux into the chambers lowered NCE values. The CO2 flux from the soil ranged from 7.2% to 28.4% of the total NCE. One needs to add soil CO2 flux rates to the measured canopy NCE rates to obtain canopy NCE rates closer to individual-leaf NCE rates. Soil CO2 flux decreased when conditions became dry, reaching a low of 0.06 mg CO2m−2s−1, but increased after rain to 0.16 mg CO2m−2s−1. Also, after rain, when plants were well watered, they were not light saturated at 1 900 µEm−2s−1. The NCE rates on the burned treatment were either higher or similar to those on the unburned treatment. For example, on 11 July 1987, NCE rates were higher on the burned treatment (0.66 mg CO2m−2s−1) compared to the unburned treatment (0.47 mg CO2m−2s−1). During the rest of July and August, the rates of the two treatments were not significantly different. But in September and October, the NCE rates were again higher on the burned treatment compared to the unburned treatment. The results indicated that canopy NCE rates may be more indicative of the productivity of the prairie than individual-leaf measurements made only on young, highly productive leaves.

Experimental analysis of patch dynamics and community heterogeneity in tallgrass prairie

Effects of fire and small-scale soil disturbances on species richness, community heterogeneity, and microsuccession were investigated in a central Oklahoma tallgrass prairie. In the fall of 1985, 0.2 m2 soil disturbances were created on burned and unburned tallgrass prairie. Vegetation on and off disturbances was sampled at monthly intervals over two growing seasons. During the first growing season, the cover of forbs and annuals, and species richness were significantly greater on versus off disturbances, but these differences did not persist through the second year. The variation in species composition among disturbed plots (heterogeneity) was significantly greater compared to undisturbed areas throughout the study. Fire had no consistent effect on richness and heterogeneity of vegetation on soil disturbances but fire reduced heterogeneity on undisturbed vegetation. Rate of succession, based on an increase in cumulative cover of perennial grasses over time, did not differ among treatments during the first growing season. During the second year, rate of succession was significantly greater on burned soil disturbances compared to unburned soil disturbances. These results suggest that while small-scale soil disturbances have primarily short-lived effects on grassland community structure, disturbances do help to maintain spatial and temporal variation in tallgrass prairie communities. Unlike in undisturbed vegetation, however, species richness and heterogeneity on soil disturbances were little effected by fire, but the rate of colonization onto disturbances appeared to be enhanced by fire.

Nitrogen dynamics of soil water in burned and unburned tallgrass prairie

Porous cup lysimeters were used to study the effects of spring burning for 5 yr on soil water N dynamics of tallgrass prairie. NO 3 −−N concentrations within the rooting zone (20 cm depth) were unaffected by burning and averaged 27μg 1 −1. Concentrations at 80cm were also similar for burned and unburned prairie and averaged 13μg 1 −1. Organic N was the dominant form of N in soil water, and showed a strong effect of treatment and depth. Organic N concentrations averaged 409 μg 1 −1 at 20cm depth on unburned watersheds versus 295 μg 1 −1 on burned watersheds ( P<0.05). Values were not influenced by burning at 80 cm depths but were 30–50% lower than those observed at 20 cm. Soil water N concentrations averaged <30% of those observed in bulk precipitation inputs, and while fire is responsible for the maintenance of the tallgrass prairie flora, fire does not appear to be an important factor affecting groundwater export of N in this biome. Total N concentrations increased from an average of ca. 200 μg 1 −1 in 1982 to an average of ca. 400 μg 1 −1 during 1986, while lysimeter volumes declined from > 400 to ca. 200 ml sample −1. These changes were not related to precipitation, and suggests that the soil environment sampled by the lysimeters changes through time.

Mass, Nitrogen, and Phosphorus Dynamics in Foliage and Root Detritus of Tallgrass Prairie

Mass nitrogen, and phosphorus of litterfall were measured for 4 yr on annually burned and unburned tallgrass prairie near Manhattan, Kansas. Decomposition and minearilization rates of foliage, flowering stem, and roots were concurrently studied with a series of litterbag and tethered litter experiments. Amounts of nitrogen and phosphorus in living and dead foilage and roots were measured for 2—yr on an annually burned site. Litterfall exhibited seasonal peaks on all sites, with most of the annual litter decompsition occurring in autumn. An average of 52 g°m—2°yr—1 of litter was deposited on the soil of the annually burned watersheds, while 142 g°m—2°—1 was collected on unburned sites. Nitrogen and phosphorus amounts were 0.53 and 0.07 g°m—2°yr—1, respectively, from burned sites and 1.94 and 0.19 g°m—2°yr—1, on unburned sites. Litterfall on unburned sites averaged °35% of aboveground maximum biomass estimates. Litter decay rates varied from a minimum of °10% yr for flowering stems in the canopy to a maximum of °50%/ yr for roots. Foilage and stems act as nitrogen and phosphorus sinks during the first 2 yr of decomposition. Dead roots and rhizomes also act as temporary nitrogen sinks, but unlike foilage, roots appear to minearlize significant amounts of phosphorus during the 1st yr of decay. Root nitrogen to phosphorus ratios may provide a proximate explanation for nitrogen limitation in tallgrass prairies.

Canopy Rainfall Interception and Throughfall in Burned and Unburned Tallgrass Prairie

Canopy Rainfall Interception and Throughfall in Burned and Unburned Tallgrass Prairie

RESPONSE OF ANDROPOGON GERARDII (POACEAE) TO FIRE‐INDUCED HIGH VS. LOW IRRADIANCE ENVIRONMENTS IN TALLGRASS PRAIRIE: LEAF STRUCTURE AND PHOTOSYNTHETIC PIGMENTS

Photosynthetic pigments and several structural characteristics were measured in leaves of Andropogon gerardii from tallgrass prairie populations in an unburned, low‐irradiance site and a burned, high‐irradiance site to determine if these species displayed sun/shade differences similar to those documented in forest species. Early in the growing season, leaves of A. gerardii in the low‐irradiance, unburned site had significantly lower stomatal density, pore length, and conductance, as well as specific leaf mass and thickness than leaves from the high‐irradiance, burned site. Moreover, the chlorophyll a:b ratio, carotenoid content, and bundle sheath‐vascular complex area were significantly lower, but chlorophyll content (mass/mass) was greater in leaves in unburned vs. burned sites. These differences are consistent with sun/shade adaptations reported for forest understory plants and may contribute to the low productivity of A. gerardii in unburned tallgrass prairie.

Response of Andropogon gerardii (Poaceae) to Fire-Induced High vs. Low Irradiance Environments in Tallgrass Prairie: Leaf Structure and Photosynthetic Pigments

Photosynthetic pigments and several structural characteristics were measured in leaves of Andropogon gerardii from tallgrass prairie populations in an unburned, low-irradiance site and a burned, high-irradiance site to determine if these species displayed sun/shade differences similar to those documented in forest species. Early in the growing season, leaves of A. gerardii in the low-irradiance, unburned site had significantly lower stomatal density, pore length, and conductance, as well as specific leaf mass and thickness than leaves from the high-irradiance, burned site. Moreover, the chlorophyll a:b ratio, carotenoid content, and bundle sheath-vascular complex area were significantly lower, but chlorophyll content (mass/mass) was greater in leaves in unburned vs. burned sites. These differences are consistent with sun/shade adaptations reported for forest understory plants and may contribute to the low productivity of A. gerardii in unburned tallgrass prairie.

Canopy interception of nitrogen in bulk precipitation by annually burned and unburned tallgrass prairie.

Nitrogen content of bulk precipitation and throughfall (canopy leachates) was measured on annually burned and unburned tallgrass prairie during a 20 month period. Throughfall amounts averaged 58% of precipitation on unburned prairie while throughfall on annually burned sites averaged 76% of precipitation inputs. Stemflow was measured in late summer and autumn. Volumes were correlated with stem density; maximum stemflow volumes measured in this study averaged about 50% of throughfall volumes.Bulk precipitation averaged 530, 456, and 420 μg/l of nitrate, ammonium and organic nitrogen, respectively. Throughfall on burned sites averaged 345, 344 and 980 μg/l of nitrate, ammonium and organic nitrogen, and throughfall on unburned sites averaged 258, 196 and 1701 μg/l of nitrate, ammonium and organic nitrogen. Microbes on standing dead vegetation and litter of the unburned sites were estimated to remove more inorganic nitrogen from bulk precipitation than did foliage on burned sites. Only a portion of the inorganic nitrogen in bulk precipitation is immediately available for plant use, and this availability is influenced by the amount of detritus present on the prairie.

Belowground Macroarthropods of Annually Burned and Unburned Tallgrass Prairie

Belowground Macroarthropods of Annually Burned and Unburned Tallgrass Prairie