Heat Shielding: A Novel Method of Colonial Thermoregulation in Honey Bees

 Honey bees, Apis mellifera, maintain constant colony temperatures throughout the year. Honey bees fan their wings to cool the colony, and often spread fluid in conjunction with this behavior to induce evaporative cooling. We present an additional, previously undescribed mechanism used by the honey bee to maintain constant colony temperature in response to localized temperature increases. Worker bees shield the comb from external heat sources by positioning themselves on hot interior regions of the hive's walls. Although honey comb and brood comb were both shielded, the temperature-sensitive brood received a greater number of heat shielders and was thus better protected from overheating. Heat shielding appears to be a context-dependent adaptive behavior performed by worker bees who would previously have been considered "unemployed." Received: 16 November 1998 / Accepted in revised form: 31 March 1999     

Modeling Hydrologic Benefits of Low Impact Development: A Distributed Hydrologic Model of The Woodlands,Texas

Low Impact Development (LID) is alternative design approach to land development that conserves and utilizes natural resources to minimize the potential negative environmental impacts of development, such as flooding. The Woodlands near Houston, Texas is one of the premier master‐planned communities in the United States. Unlike in a typical urban development where riparian corridors are often replaced with concrete channels, pervious surfaces, vegetation, and natural drainage pathways were preserved as much as possible during development. In addition, a number of detention ponds were strategically located to manage runoff on site. This article uses a unique distributed hydrologic model, Vflo?, combined with historical (1974) and recent (2008 and 2009) rainfall events to evaluate the long‐term effectiveness of The Woodlands natural drainage design as a stormwater management technique. This study analyzed the influence of LID in The Woodlands by comparing the hydrologic response of the watershed under undeveloped, developed, and highly urbanized conditions. The results show that The Woodlands drainage design successfully reflects predeveloped hydrologic conditions and produces peak flows two to three times lower than highly urbanized development. Furthermore, results indicate that the LID practices employed in The Woodlands successfully attenuate the peak flow from a 100‐year design event, resulting in flows comparable to undeveloped hydrologic conditions.     

Nepalganj,the centre of the world: local perceptions of environmental change and the roles of climate-change adaptation actors

This paper explores community perspectives of environmental change and the role development actors in the regional Nepali town of Nepalganj. Understanding these perceptions is crucial for planning future adaptation to climate change and ensuring that these measures are sustainable and in line with community priorities. Firstly, I contend that whilst the local community in Nepalganj may be experiencing the impacts of climate change, they are unfamiliar and disassociated with the concept. Secondly, I identify a number of risks and opportunities around the role of local government, international development organisations and local non-government organisations in future adaptation actions. Participant perceptions of these institutions in their community reinforce a number of established critiques of development around themes such as poor consultation and short project timelines. The long-term success of adaptation actions will be shaped by the ability and willingness of development actors to evolve their practices by listening to local communities.     

Simulation of Daily Flow Pathways,Tile‐Drain Nitrate Concentrations,and Soil‐Nitrogen Dynamics Using SWAT

Tile drainage significantly alters flow and nutrient pathways and reliable simulation at this scale is needed for effective planning of nutrient reduction strategies. The Soil and Water Assessment Tool (SWAT) has been widely utilized for prediction of flow and nutrient loads, but few applications have evaluated the model's ability to simulate pathway‐specific flow components or nitrate‐nitrogen (NO₃‐N) concentrations in tile‐drained watersheds at the daily time step. The objectives of this study were to develop and calibrate SWAT models for small, tile‐drained watersheds, evaluate model performance for simulation of flow components and NO₃‐N concentration at daily intervals, and evaluate simulated soil‐nitrogen dynamics. Model evaluation revealed that it is possible to meet accepted performance criteria for simulation of monthly total flow, subsurface flow (SSF), and NO₃‐N loads while obtaining daily surface runoff (SURQ), SSF, and NO₃‐N concentrations that are not satisfactory. This limits model utility for simulating best management practices (BMPs) and compliance with water quality standards. Although SWAT simulates the soil N‐cycle and most predicted fluxes were within ranges reported in agronomic studies, improvements to algorithms for soil‐N processes are needed. Variability in N fluxes is extreme and better parameterization and constraint, through use of more detailed agronomic data, would also improve NO₃‐N simulation in SWAT. Editor's note : This paper is part of the featured series on SWAT Applications for Emerging Hydrologic and Water Quality Challenges. See the February 2017 issue for the introduction and background to the series.     

Water Quality Assessment of Large‐scale Bioenergy Cropping Scenarios for the Upper Mississippi and Ohio‐Tennessee River Basins

The Upper Mississippi River Basin and Ohio‐Tennessee River Basin comprise the majority of the United States Corn Belt region, resulting in degraded Mississippi River and Gulf of Mexico water quality. To address the water quality implications of increased biofuel production, biofuel scenarios were tested with a Soil and Water Assessment Tool (SWAT) model revision featuring improved biofuel crop representation. Scenarios included corn stover removal and the inclusion of two perennial bioenergy crops, switchgrass and Miscanthus, grown on marginal lands (slopes >2% and erosion rates >2 t/ha) and nonmarginal lands. The SWAT model estimates show water quality is not very sensitive to stover removal. The perennial bioenergy crops reduce simulated sediment, nitrogen (N), and phosphorus (P) yields by up to 60%. Simulated sediment and P reductions in marginal lands were generally twice that occurring in the nonmarginal lands. The highest unit area reductions of N occurred in the less sloping tile‐drained lands. Productivity showed corn grain yield was independent from stover removal, while yields of the two perennial bioenergy crops were similar in the marginal and nonmarginal lands. The results suggest planning for biofuel production in the Corn Belt could include the removal of stover in productive corn areas, and the planting of perennial bioenergy crops in marginal land and in low‐sloped tile‐drained areas characterized by high N pollution. Editor's note : This paper is part of the featured series on SWAT Applications for Emerging Hydrologic and Water Quality Challenges. See the February 2017 issue for the introduction and background to the series.     

Carbon benefits from Amazonian forest reserves: leakage accounting and the value of time

Amazonian forest reserves have significant carbon benefits, but the methodology used for accounting for these benefits will be critical in determining whether the powerful economic force represented by mitigation efforts to slow global warming will be applied to creating these reserves. Opportunities for reserve creation are quickly being lost as new areas are opened to deforestation though highway construction and other developments. Leakage, or the effects that a reserve or other mitigation project provokes outside of the project boundaries, is critical to a proper accounting of net carbon benefits. Protected areas in the Amazon have particularly great potential mitigation benefits over an extended time horizon. Over a 100-year time frame, virtually no unprotected forest is likely to remain, meaning that potential leakages (both leakage to the vicinity of the reserves and that displaced by removing protected areas from the land-grabbing market) should not matter much because any short-term leakage would be “recovered” eventually. The effect of the value attributed to time greatly influences the impact of leakage on benefits credited to reserves. Simple assumptions regarding leakage scenarios illustrate the benefits of reserves and the critical areas where agreement is necessary to make this option a practical component of mitigation efforts. The stakes are too high to allow further delays in reaching agreement on these issues.     

How Climate and Vegetation Influence the fire Regime of the Alaskan Boreal Biome: The Holocene Perspective

We synthesize recent results from lake-sediment studies of Holocene fire-climate-vegetation interactions in Alaskan boreal ecosystems. At the millennial time scale, the most robust feature of these records is an increase in fire occurrence with the establishment of boreal forests dominated by Picea mariana: estimated mean fire-return intervals decreased from ≥300 yrs to as low as ∼80 yrs. This fire-vegetation relationship occurred at all sites in interior Alaska with charcoal-based fire reconstructions, regardless of the specific time of P. mariana arrival during the Holocene. The establishment of P. mariana forests was associated with a regional climatic trend toward cooler/wetter conditions. Because such climatic change should not directly enhance fire occurrence, the increase in fire frequency most likely reflects the influence of highly flammable P. mariana forests, which are more conducive to fire ignition and spread than the preceding vegetation types (tundra, and woodlands/forests dominated by Populus or Picea glauca). Increased lightning associated with altered atmospheric circulation may have also played a role in certain areas where fire frequency increased around 4000 calibrated years before present (BP) without an apparent increase in the abundance of P. mariana. When viewed together, the paleo-fire records reveal that fire histories differed among sites in the same modern fire regime and that the fire regime and plant community similar to those of today became established at different times. Thus the spatial array of regional fire regimes was non-static through the Holocene. However, the patterns and causes of the spatial variation remain largely unknown. Advancing our understanding of climate-fire-vegetation interactions in the Alaskan boreal biome will require a network of charcoal records across various ecoregions, quantitative paleoclimate reconstructions, and improved knowledge of how sedimentary charcoal records fire events. In this paper, charcoal refers to macroscopic (≥180 μm) as opposed to microscopic (< 180 μm) particles unless indicated otherwise. Radiocarbon ages were converted to calibrated years before AD 1950 using the atmospheric calibration data set (Stuiver et al. 1998).