Optimal foraging and community structure: implications for a guild of generalist grassland herbivores

A particular linear programming model is constructed to predict the diets of each of 14 species of generalist herbivores at the National Bison Range, Montana. The herbivores have body masses ranging over seven orders of magnitude and belonging to two major taxa: insects and mammals. The linear programming model has three feeding constraints: digestive capacity, feeding time and energy requirements. A foraging strategy that maximizes daily energy intake agrees very well with the observed diets. Body size appears to be an underlying determinant of the foraging parameters leading to diet selection. Species that possess digestive capacity and feeding time constraints which approach each other in magnitude have the most generalized diets. The degree that the linear programming models change their diet predictions with a given percent change in parameter values (sensitivity) may reflect the observed ability of the species to vary their diets. In particular, the species which show the most diet variability are those whose diets tend to be balanced between monocots and dicots. The community-ecological parameters of herbivore body-size ranges and species number can possibly be related to foraging behavior.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47765/1/442_2004_Article_BF00377109.pd

obtusifolia

Ziziphus obtusifolia (Hook. ex Torr. & A. Gray) A. Graygumdroptree, lote bushCondalia lycioidesAlamo SpringLimestone soil at Alamo Spring2640 feetFrequen

Evaporation of lignin-lean black liquor

Many of the pulp mill biorefinery concepts recently presented include removal of lignin from black liquor. In this work, the aim was to study how the change in liquor chemistry affected the evaporation of kraft black liquor when lignin was removed using the LignoBoost process. Lignin was removed from a softwood kraft black liquor and four different black liquors were studied: one reference black liquor (with no lignin extracted); two ligninlean black liquors with a lignin removal rate of 5.5% and 21%, respectively; and one liquor with maximum lignin removal of 60%. Evaporation tests were carried out at the research evaporator in Chalmers University of Technology. Studied parameters were liquor viscosity, boiling point rise, heat transfer coefficient, scaling propensity, changes in liquor chemical composition, and tube incrustation. It was found that the solubility limit for incrustation changed towards lower dry solids for the lignin-lean black liquors due to an increased salt content. The scaling obtained on the tubes was easily cleaned with thin liquor at 105\ub0C. It was also shown that the liquor viscosity decreased exponentially with increased lignin outtake and hence, the heat transfer coefficient increased with increased lignin outtake. Long term tests, operated about 6 percentage dry solids units above the solubility limit for incrustation for all liquors, showed that the heat transfer coefficient increased from 650 W/m2K for the reference liquor to 1500 W/m2K for the liquor with highest lignin separation degree, 60%. Application: This study can be used to help assess the consequences for an evaporation plant concerning both changes in capacity and risk for fouling when evaluating a biorefinery concept, including lignin removal, at a mill. It also adds novel information to the research work on black liquor evaporation. Application: This study can be used to help assess the consequences for an evaporation plant concerning both changes in capacity and risk for fouling when evaluating a biorefinery concept, including lignin removal, at a mill. It also adds novel information to the research work on black liquor evaporation

capillus-veneris

Alamo Spring, Big Bend National ParkOn bluff seeps, limestone soil at Alamo Spring2640 feetInfrequent on bluff seep

Forage Diversity and Dietary Selection by Wintering Mule Deer

During a 30-day grazing trial, six mule deer (Odocoileus hemionus hemionus) at pasture altered their food selection significantly as availability of forage changed. At the beginning of the trial when forbs and grasses were abundant, they comprised better than 50% of the diet; but by the end of the trial when these preferred forages were less abundant, grass and forb declined. Shrub use increased and forb and grass use decreased as snow depths increased. Results support the conjecture that big sagebrush (Artemisia tridentata wyomingensis) in excess of 30% in the diet is detrimental to mule deer nutritional health.This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202

Effect of Woody Stems on Estimating Herbage Weights with a Capacitance Meter

Ignoring woody stems significantly improved capacitance-meter estimates of herbage weight.This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202

Evaluation of Deer Habitat on a Nutritional Basis

Protein and energy requirements of deer and supplies of these nutrients in native forage are synthesized into a model to estimate carrying capacity of seasonal ranges of a migratory mule deer population in north central Colorado. The model indicates that summer forage will support many times the number of deer present, but winter forage will not sustain deer at any population level. Instead, duration and severity of winter determine the length of time deer can survive on these ranges. Habitat evaluation based on quantification of nutrient supplies and their availability offers a more logical alternative for evaluating deer winter ranges than traditional methods based on measurements of twig lengths of so-called "key" species.This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202