Bison foraging responds to fire frequency in nutritionally heterogeneous grassland

Citation: Raynor, E. J., Joern, A., & Briggs, J. M. (2015). Bison foraging responds to fire frequency in nutritionally heterogeneous grassland. Ecology, 96(6), 1586-1597. doi:10.1890/14-2027.1Foraging decisions by native grazers in fire-dependent landscapes modulate the fire-grazing interaction. Uncovering the behavioral mechanisms associated with the attraction of grazers to recently burned areas requires understanding at multiple spatial scales in the ecological foraging hierarchy. This study focused on feeding in the area between steps in a foraging bout, the feeding station, as forage chemistry and vegetation architecture play central roles in these fine-scale, feeding-station decisions. The forage maturation hypothesis (FMH) uses the temporal dynamics of forage quality and quantity in grasslands to explain the distribution of large herbivores, but does not address herbivore responses to inter-patch variation caused by fire-induced nutrient increases of forage quality. Using an experimental setting with contrasting fire treatments we describe the effects of variable burn history on foraging kinetics by bison at Konza Prairie Biological Station (KPBS). We assessed the potential to link the FMH in a complementary fashion to the transient maxima hypothesis (TMH) to explain temporal variation in bison responses to grassland forage quality and quantity in response to burning at different temporal frequencies. Forage attributes met predictions of the TMH that allowed us to investigate how forage maturation affects feeding station foraging behavior across watersheds with varying burn frequency. At sites burned in the spring after several years without burning, both bite mass and intake rate increased with increasing biomass at a greater rate during the growing season than during the transitional midsummer seasonal period. In these infrequently burned watersheds, early growing season bite mass (0.6 +/- 0.05 g; mean +/- SE), bite rate (38 +/- 1.5 bites/ min), and intake rate (21 +/- 2.3 g/min) was reduced by similar to 15%, 13%, and 29% during the midsummer transitional period. A behavioral response in foraging kinetics at the feeding station occurred where a nonequilibrial pulse of high-quality resource was made available and then retained by repeated grazing over the growing season. Our results provide the first experimental evidence for demonstrating the fine-scale behavioral response of a large grazer to fire-induced changes in forage attributes, while linking two prominent hypotheses proposed to explain spatial variation in forage quality and quantity at local and landscape scales

The resilience of indigenous knowledge in small-scale African agriculture: key drivers

The successful use of indigenous knowledge (IK) in development practice in rural Africa over the last couple of decades has proved to be elusive and disappointing. Using empirical field data from northern Malawi, this study suggests that the two key drivers for farmers in this area are household food security and the maintenance of soil fertility. Indigenous ways of knowing underpin the agricultural system which has been developed, rather than the adoption of more modern, ‘scientific’ ways, to deliver against these drivers. Such IKs, however, are deeply embedded in the economic, social and cultural environments in which they operate

Triangulation Rangefinder and Sight Positioning System

A rangefinder includes an angle sensitive transducer and a programmed data processor to calculate the distance to a target. In one embodiment, the rangefinder also includes a point-to-point measuring device. Another embodiment provides a linear actuator to selectively move a sight indicator vertically. A yet additional embodiment includes a liquid crystal display which displays information to the user

Triangulation Rangefinder for Archers

An archery rangefinder for use from an elevated position comprises a power supply for an electronic digital panel meter and a power supply for two voltage divider circuits that comprise the rangefinding circuit. One voltage divider provides a voltage signal proportional to the elevation distance. This signal acts to supply the second voltage divider to attenuate the voltage further by a factor proportional to the tangent of the inclination angle. A weighted pendulum arm is attached to a potentiometric element in the second voltage divider to effect feedback relevant to the angle of inclination. All circuits and components are housed within an outer protective enclosure. Voltage across a fixed resistor in the second voltage divider is read and displayed by said digital panel meter as the range which is then used by the archer to increase accuracy of shots