Optimal fire management for maintaining community diversity

Disturbance events strongly influence the dynamics of plant and animal populations within nature reserves. Although many models predict the patterns of succession following a disturbance event, it is often unclear how these models can be used to help make management decisions about disturbances. In this paper we consider the problem of managing fire in Ngarkat Conservation park (CP), South Australia, Australia. We present a methematical model of community succession following a fire disturbance event. Ngarkat CP is a key habitat for several nationally rare and threatened species of birds, and because these species prefer different successional communities, we assume that the primary management objective is to maintain community diversity within the park. More specifically, the aim of management is to keep at least a certain fraction of the park, (e.g. 20%) in each of three successional stages. We assume that each year a manager may do one of the following: let wildfires burn unhindered, fight wildfires, or perform controlled burns. We apply stochastic dynamic programming to identify which of these three strategies is optimal, i.e. the one most likely to promote community diversity. Model results indicate that the optimal management strategy depends on the current state of the park, the cost associated with each strategy, and the time frame over which the manager has set his/her goal

Abortive Lytic Reactivation of KSHV in CBF1/CSL Deficient Human B Cell Lines

Since Kaposi's sarcoma associated herpesvirus (KSHV) establishes a persistent infection in human B cells, B cells are a critical compartment for viral pathogenesis. RTA, the replication and transcription activator of KSHV, can either directly bind to DNA or use cellular DNA binding factors including CBF1/CSL as DNA adaptors. In addition, the viral factors LANA1 and vIRF4 are known to bind to CBF1/CSL and modulate RTA activity. To analyze the contribution of CBF1/CSL to reactivation in human B cells, we have successfully infected DG75 and DG75 CBF1/CSL knock-out cell lines with recombinant KSHV.219 and selected for viral maintenance by selective medium. Both lines maintained the virus irrespective of their CBF1/CSL status. Viral reactivation could be initiated in both B cell lines but viral genome replication was attenuated in CBF1/CSL deficient lines, which also failed to produce detectable levels of infectious virus. Induction of immediate early, early and late viral genes was impaired in CBF1/CSL deficient cells at multiple stages of the reactivation process but could be restored to wild-type levels by reintroduction of CBF1/CSL. To identify additional viral RTA target genes, which are directly controlled by CBF1/CSL, we analyzed promoters of a selected subset of viral genes. We show that the induction of the late viral genes ORF29a and ORF65 by RTA is strongly enhanced by CBF1/CSL. Orthologs of ORF29a in other herpesviruses are part of the terminase complex required for viral packaging. ORF65 encodes the small capsid protein essential for capsid shell assembly. Our study demonstrates for the first time that in human B cells viral replication can be initiated in the absence of CBF1/CSL but the reactivation process is severely attenuated at all stages and does not lead to virion production. Thus, CBF1/CSL acts as a global hub which is used by the virus to coordinate the lytic cascade

Natural Resources Research Institute Technical Report

Natural Resources Research Institute, University of Minnesota Duluth, Prepared for: Minnesota Technology, Inc.; Reporting Period: July 1, 1994 - December 31, 1994Semi-Annual progress and financial report that provides technical assistance to Minnesota's peat industry through research, advice on regulatory matters, administrative support, and education about Minnesota's peat industry

Natural Resources Research Institute Technical Report

Revised 10/03/94; Subaccount No. 543845; This report is the Final Report for Phase III of the Minnesota Office of Environmental Assistance funded project "Evaluation of Uses of De-inking Residue." Phase III of this project was previously entitled "Mineland Reclamation." Prepared for: Minnesota Office of Environmental Assistance, 1350 Energy Lane, St. Paul, MN 55108Pulp facilities which recycle office waste paper generate a large amount of waste by-products in the process of producing high-grade pulp. The paper-like residue, called de-inking residue, was evaluated for use in the restoration of vegetation on coarse taconite tailings in NE Minnesota. The mineland reclamation rules specify that a 90 percent vegetative cover shall be established on tailings after three growing seasons, however this level of cover on coarse tailings has not been consistently achieved in Minnesota using standard restoration practices. Research plots were established in 1992 at Eveleth Mines arranged in a randomized block design with three replications using five levels of de-inking residue, five levels of fertilization and two plant mixes. A total of twenty-five treatment combinations were assigned to 2.5m- by- 4.0m plots and lysimeters were installed to monitor changes in sub-surface water quality. Coarse tailings were evaluated to determine the effects of de-inking residue on their chemical properties. Vegetative cover was measured in July and September in 1992 and 1993 and nutrient levels were determined in plant samples. Fertilization and de-inking residue amendments had significant effects on the vegetative cover of both introduced and native plant species. De-inking residue had a minimal impact on the chemical properties of coarse tailings at rates up to 80 dry ton/acre and on sub-surface water quality at a depth of four feet. Vegetative cover for introduced species increased from no cover, to 49 percent the first growing season, to 90 percent at the end of the second growing season on tailings fertilized at the highest level and amended with residue at 10 ton/acre. At the same fertilizer and de-inking residue rate, vegetative cover for native plants increased from no cover to 7 percent the first growing season, to 69 percent at the end of the second growing season. Alfalfa had lower levels of boron, magnesium, and manganese on residue amended plots in 1992 and 1993. Bluestem had higher levels of calcium and zinc, but lower levels of magnesium and manganese on residue amended. plots. Cadmium, chromium, copper, nickel, lead, and zinc in alfalfa and bluestem did not accumulate to toxic levels. Deinking residue appears to have benefited vegetative growth after two growing seasons using deinking residue applied at 10 dry ton/acre with fertilizer applied at 160 lb/acre of nitrogen and 359 lb/acre of phosphorus.University of Minnesota Duluth, Natural Resources Research Institute, 5013 Miller Trunk Highway, Duluth, MN 55811-144