Effects of Patch-Burn Management on Dickcissel Nest Success in a Tallgrass Prairie

Abstract Grassland birds have declined more than any other North American habitat-associated bird community. Because most species of grassland birds evolved within heterogeneous landscapes created by the interaction of fire and grazing, traditional rangeland management that promotes homogeneity, including annual dormant-season burning combined with early-intensive grazing, might be partly responsible for these declines, especially in some regions of the Great Plains, USA. Recently, an alternative grassland management practice known as patch-burning has been promoted as a means of restoring heterogeneity to grasslands by mimicking the grazing-fire interaction that once occurred on the prairie before European settlement. From 2003 to 2004, we examined effects of patch-burning and traditional management (annual burning followed by early-intensive grazing) on the reproductive success of dickcissels (Spiza americana) in tallgrass prairie in Oklahoma. We monitored 296 dickcissel nests and found that dickcissel nesting phenology differed between traditional and patch-burned pastures. Specifically, dickcissels tended to initiate their nests later in the traditional pasture. Mean number of eggs laid and fledglings produced were similar between the treatments, but nest densities were higher in traditional pastures. Predation was the predominant cause of nest failure and was higher in traditional pastures than in patch-burned pastures. Brown-headed cowbird (Molothrus ater) parasitism was higher in traditional pastures than in patch-burned pastures. Overall, dickcissel nest success was higher in patch-burned pastures than in traditional pastures. The positive response of dickcissel nest success to patch-burn management provides further evidence that this practice can be a useful tool for grassland bird conservation. By creating a mosaic of different stature vegetation, patch-burn management enhances productivity of grassland bird species by providing a refuge area in the unburned patches that affords dickcissels and other nesting grassland birds some protection from the direct (e.g., trampling) and indirect (e.g., cowbird parasitism and predation) effects of grazing, which are not available under traditional management. Patch-burn management should be encouraged as a conservation strategy for grassland birds throughout the Great Plains.     

Economic incentives for conservation: beekeeping and Saturniidae caterpillar utilization by rural communities

The economic viability of the wildlife based enterprises (bee-keeping and caterpillar utilization) in Malawi is discussed in relation to conventional agricultural enterprises (maize, beans and ground-nuts). A strong incentive emerges for rural people to adopt wildlife management as an adjunct to subsistence agriculture, and therefore, to promote conservation of natural ecosystems and wildlife habitats in the face of growing human population and demand for land. Dependence on agriculture has depleted the wildlife resource outside protected areas and has been less effective in improving the wealth and living standards of most rural people. This study illustrates that the Malawi Department of National Parks and Wildlife needs to introduce economic incentives that integrate biological conservation with economic development for the rural people. The management programme involves the adoption of a rotation burning policy that promotes vegetation coppicing, eases harvesting and promotes high caterpillar yields.     

Nutrient fluxes in the shifting cultivation system of south-west Côte d'Ivoire

At two sites, one with a 4-year-old (4-Y) secondary vegetation and the other with a 20-year-old (20-Y) vegetation, the influence of burning slashed vegetation on crop performance was studied during three seasons. In the first season after clearing, also the influence on weed growth was studied. At both sites, burning significantly decreased the number of weed seedlings. The lowest number of seedlings was found on the burnt plots of the 20-Y site. Burning increased yield and nutrient uptake significantly in the first and second season after clearing. In the third season after burning, only at the 4-Y site a significantly higher yield and nutrient uptake were found. At the 20-Y site the effect had disappeared. Calculations of efficiency of utilization of absorbed N, P and K indicated that P was the least available nutrient, also after burning. At both sites three consecutive crops absorbed approximately 40% of P applied in ash, while the cumulative recovery of K was at least 36% at the 4-Y site and at least 59% at the 20-Y site. On non-burnt plots, yields were not lower in the third season than in the first season after clearing, thus indicating that the inherent soil fertility did not decrease. Hence, yield decline on the burnt plots could be ascribed to ash depletion. It was concluded that in the local shifting cultivation system, the combination of ash depletion and infestation of weeds are the main reasons for abandoning the fields.     

Changes in the floristic composition of a Quercus coccifera L. garrigue in relation to different fire regimes

Plant Ecology - To analyse the impact of fire on plants, an experiment has been set up in a Quercus coccifera L. garrigue near Montpellier. The objectives of the study were to follow the changes of...     

Short- and Long-term Changes in Elk Use and Forage Production in Sagebrush Communities Following Prescribed Burning

Burning shrub and grassland communities often leads to increases in plant production and nutritional quality that benefit herbivores, resulting in increased herbivore use of burned areas. Increased use has been ascribed more specifically to changes in plant community structure, community composition and diversity, nutritional quality, and seasonal availability. These hypotheses can be evaluated more precisely if changes in plant communities following burning are monitored concurrently with changes in herbivore use, especially in longer-term studies. From 1988 to 1999, we examined responses of elk (Cervus elaphus) following prescribed burning of areas burned in 1984 and 1988 that had been formerly dominated by mountain big sagebrush (Artemisia tridentata ssp. vaseyana) in south-central Montana (USA), with concurrent monitoring of changes in plant production, nutritional quality, and community composition. Elk made increased use of burned sites up to 15 years after burning. Burning transformed big sagebrush-dominated communities into native herbaceous communities that persisted for 15 years without sagebrush reinvasion. Forage biomass and protein content remained higher on burned sites for 15 years, although differences were not significant in every year and declined as time elapsed after burning. Forage production, forage protein, and elk use were temporally correlated, suggesting the possibility that grazing by elk might have contributed to persistence of elevated plant production and protein levels on burned sites.     

Codoped Holey Graphene Aerogel by Selective Etching for High‐Performance Sodium‐Ion Storage

The pursuit of more efficient carbon‐based anodes for sodium‐ion batteries (SIBs) prepared from facile and economical methods is a very important endeavor. Based on the crystallinity difference within carbon materials, herein, a low‐temperature selective burning method is developed for preparing oxygen and nitrogen codoped holey graphene aerogel as additive‐free anode for SIBs. By selective burning of a mixture of graphene and low‐crystallinity carbon at 450 °C in air, an elastic porous graphene monolith with abundant holes on graphene sheets and optimized crystallinity is obtained. These structural characteristics lead to an additive‐free electrode with fast charge (ions and electrons) transfer and more abundant Na⁺ storage active sites. Moreover, the heteroatom oxygen/nitrogen doping favors large interlayer distance for rapid Na⁺ insertion/extraction and provides more active sites for high capacitive contribution. The optimized sample exhibits superior sodium‐ion storage capability, i.e., high specific capacity (446 mAh g^?1 at 0.1 A g^?1), ultrahigh rate capability (189 mAh g^?1 at 10 A g^?1), and long cycle life (81.0% capacity retention after 2000 cycles at 5 A g^?1). This facile and economic strategy might be extended to fabricating other superior carbon‐based energy storage materials.     

Facilitating Establishment of Advance Regeneration of Pterocarpus santalinus L.—An Endangered Tree Species from India

Red sanders (Pterocarpus santalinus L.) is an endangered and endemic tropical tree species from India in need of restoration. This study evaluated options for improving establishment of its advance regeneration in degraded forests. Using randomized complete block design, the effect of silvicultural treatments involving prescribed fire, in combination with disking, singling, disking with singling, and control (no treatment) on survival and growth of advanced regeneration were evaluated for a period of 2 years. Results indicate that the treatments served to ameliorate microsite conditions resulting in better survival and growth. Seedlings with fewer coppice shoots, treatments with a singling component, and treatments with disking component showed better survival and growth. The number and height of other neighboring seedlings and trees also influenced seedling establishment. Seedlings showed significantly higher survival results in the prescribed fire with disking (disking with prescribed burn [DPB]: 96%) and prescribed fires with disking and singling (singling plus disking with prescribed burn [SDPB]: 94%) treatments. Similarly, tall seedlings and those with larger root collar diameters accrued significantly higher volume growth in DPB (87%) and SDPB (97%) treatments. Although seedlings showed similar increments in DPB and SDPB treatments, better survival due to singling indicated the latter as the best option. In dense regeneration areas, preferential treatment of the taller and larger stump‐sized seedlings and, in limited regeneration areas that of smaller seedlings, may yield better results. Additionally, removal of competing vegetation and canopy opening may also help establishment of young regeneration. The results of this study have applications for restoration of endangered species in other tropical dry deciduous ecosystems worldwide.     

A large proportion of North American net ecosystem production is offset by emissions from harvested products,river/stream evasion,and biomass burning

Diagnostic carbon cycle models produce estimates of net ecosystem production (NEP, the balance of net primary production and heterotrophic respiration) by integrating information from (i) satellite‐based observations of land surface vegetation characteristics; (ii) distributed meteorological data; and (iii) eddy covariance flux tower observations of net ecosystem exchange (NEE) (used in model parameterization). However, a full bottom‐up accounting of NEE (the vertical carbon flux) that is suitable for integration with atmosphere‐based inversion modeling also includes emissions from decomposition/respiration of harvested forest and agricultural products, CO₂ evasion from streams and rivers, and biomass burning. Here, we produce a daily time step NEE for North America for the year 2004 that includes NEP as well as the additional emissions. This NEE product was run in the forward mode through the CarbonTracker inversion setup to evaluate its consistency with CO₂ concentration observations. The year 2004 was climatologically favorable for NEP over North America and the continental total was estimated at 1730 ± 370 TgC yr^?1 (a carbon sink). Harvested product emissions (316 ± 80 TgC yr^?1), river/stream evasion (158 ± 50 TgC yr^?1), and fire emissions (142 ± 45 TgC yr^?1) counteracted a large proportion (35%) of the NEP sink. Geographic areas with strong carbon sinks included Midwest US croplands, and forested regions of the Northeast, Southeast, and Pacific Northwest. The forward mode run with CarbonTracker produced good agreement between observed and simulated wintertime CO₂ concentrations aggregated over eight measurement sites around North America, but overestimates of summertime concentrations that suggested an underestimation of summertime carbon uptake. As terrestrial NEP is the dominant offset to fossil fuel emission over North America, a good understanding of its spatial and temporal variation – as well as the fate of the carbon it sequesters ─ is needed for a comprehensive view of the carbon cycle.     

THE BENTHIC MACROINVERTEBRATE FAUNA OF A SOUTH AFRICAN MOUNTAIN STREAM AND ITS RESPONSE TO FIRE

Summary

The effects of a late-summer prescribed burn on the temperature and benthic macroinvertebrate fauna of a south-western Cape mountain stream were investigated over a period of 12 months. Temperature and discharge regimes appear well-defined and relatively predictable from year to year. As in other mediterranean-type ecosystems, seasonal changes in the structure of the invertebrate community and the relative abundance of different feeding groups appear to be associated primarily with changes in the physical environment. Distinctive summer and winter communities were identified, with chironomids dominating the fauna in summer and simuliids dominant in winter. Although the riparian vegetation was only slightly damaged by the fire, a heavy, aseasonal leaf-fall occurred shortly afterwards. The canopy remained sparse for approximately four months. Stream temperature in the post-burn year was not demonstrably affected by increased exposure to solar radiation, however, probably because the canopy remained open during the winter months. The fire appeared to have little effect on the invertebrate fauna. Apart from five rare elements of the biota, all species recorded in the pre-burn year were present in the post-burn year and in similar densities. It is concluded that the riparian vegetation is of major importance in maintaining the integrity of the stream environment.     

Gopher Tortoise Demographic Responses to a Novel Disturbance Regime

The long-term viability of gopher tortoise (Gopherus polyphemus) populations is jeopardized by increased urbanization and habitat degradation owing to fire suppression. Because the species' remaining natural habitats in the southeastern United States exist within a mosaic of anthropogenic land uses, it is important to understand demographic responses to contrasting land uses and habitat management regimes. We examined differences in demographic parameters among fire-suppressed sandhill, restored sandhill, and former sandhill (i.e., ruderal) land use-land cover (LULC) types at Archbold Biological Station in south-central Florida, USA. Using Program MARK, we estimated population size, and sex-specific and LULC-specific survivorship based on 6 years of mark-recapture data. We also analyzed individual growth trajectories and clutch sizes to determine whether growth rates or reproductive output differed among LULC types. Tortoises in an open, ruderal field occurred at a higher density (7.79/ha) than in adjacent restored (1.43/ha) or fire-suppressed (0.40/ha) sandhill. Despite this higher density, both adult survivorship and body size were significantly higher in the ruderal field. Furthermore, the larger female body size in the ruderal field likely contributed to increased annual survivorship and slightly larger average clutch sizes. We did not detect offsetting negative demographic effects; in particular, we did not find significant biological or statistical differences in body condition, asymptotic body size, or growth rate among the 3 LULC types. Our results suggest that anthropogenic, grass-dominated land-cover types may be important components of the habitat mosaic currently available to this at-risk species. © 2019 The Wildlife Society.