Moving beyond the concept of "primary forest" as a metric of forest environment quality.

The United Nations Food and Agriculture Organization (FAO) has been reporting country-level area in primary forests in its Global Forest Resource Assessment since 2005. The FAO definition of a primary forest (naturally regenerated forest of native species where there are no clearly visible indications of human activities and the ecological processes are not significantly disturbed) is generally accepted as authoritative and is being used in policy making. However, problems with this definition undermine our capacity to obtain globally coherent estimates. In addition, the current reporting on primary forests fails to consider the complementarily of non-primary forests toward the maintenance of ecosystem services. These issues undermine the appropriate tracking of changes in primary and non-primary forests, and the assessment of impacts of such changes on ecosystem services. We present the case for an operational reconsideration of the primary forest concept and discuss how alternatives or supplements might be developed.

Bulgeless dwarf galaxies and dark matter cores from supernova-driven outflows.

For almost two decades the properties of 'dwarf' galaxies have challenged the cold dark matter (CDM) model of galaxy formation. Most observed dwarf galaxies consist of a rotating stellar disk embedded in a massive dark-matter halo with a near-constant-density core. Models based on the dominance of CDM, however, invariably form galaxies with dense spheroidal stellar bulges and steep central dark-matter profiles, because low-angular-momentum baryons and dark matter sink to the centres of galaxies through accretion and repeated mergers. Processes that decrease the central density of CDM halos have been identified, but have not yet reconciled theory with observations of present-day dwarfs. This failure is potentially catastrophic for the CDM model, possibly requiring a different dark-matter particle candidate. Here we report hydrodynamical simulations (in a framework assuming the presence of CDM and a cosmological constant) in which the inhomogeneous interstellar medium is resolved. Strong outflows from supernovae remove low-angular-momentum gas, which inhibits the formation of bulges and decreases the dark-matter density to less than half of what it would otherwise be within the central kiloparsec. The analogues of dwarf galaxies-bulgeless and with shallow central dark-matter profiles-arise naturally in these simulations.

Mountain pine beetle and forest carbon feedback to climate change.

The mountain pine beetle (Dendroctonus ponderosae Hopkins, Coleoptera: Curculionidae, Scolytinae) is a native insect of the pine forests of western North America, and its populations periodically erupt into large-scale outbreaks. During outbreaks, the resulting widespread tree mortality reduces forest carbon uptake and increases future emissions from the decay of killed trees. The impacts of insects on forest carbon dynamics, however, are generally ignored in large-scale modelling analyses. The current outbreak in British Columbia, Canada, is an order of magnitude larger in area and severity than all previous recorded outbreaks. Here we estimate that the cumulative impact of the beetle outbreak in the affected region during 2000-2020 will be 270 megatonnes (Mt) carbon (or 36 g carbon m(-2) yr(-1) on average over 374,000 km2 of forest). This impact converted the forest from a small net carbon sink to a large net carbon source both during and immediately after the outbreak. In the worst year, the impacts resulting from the beetle outbreak in British Columbia were equivalent to approximately 75% of the average annual direct forest fire emissions from all of Canada during 1959-1999. The resulting reduction in net primary production was of similar magnitude to increases observed during the 1980s and 1990s as a result of global change. Climate change has contributed to the unprecedented extent and severity of this outbreak. Insect outbreaks such as this represent an important mechanism by which climate change may undermine the ability of northern forests to take up and store atmospheric carbon, and such impacts should be accounted for in large-scale modelling analyses.

Experience with the antibiotic resistance analysis and DNA fingerprinting in tracking faecal pollution at two lake beaches.

Posting or closing of swimming beaches because of faecal contamination is a widespread problem reported in many locations. In a risk-based approach to this problem, the risk to swimmers' health is assessed by field monitoring of indicator bacteria and the associated risks are managed by source controls and other remedial measures. In risk assessment, great advances have been made in recent years with the introduction of microbial source tracking (MST) techniques. Two such techniques, antibiotic resistance analysis and DNA fingerprinting, were applied in a study of causes of faecal contamination at two lake beaches in Toronto, Ontario. Both methods identified bird faeces as the dominant sources of E. coli. Coping with this type of pollution presents a major environmental challenge.

Parity violation in proton-proton scattering at 221 MeV.

The parity-violating longitudinal analyzing power, A(z), has been measured in pvectorp elastic scattering at an incident proton energy of 221 MeV. The result obtained is A(z) = [0.84+/-0.29(stat)+/-0.17(syst)]x10(-7). This experiment is unique in that it selects a single parity violating transition amplitude (3P2 - 1D2) and consequently directly constrains the weak meson-nucleon coupling constant h(pp)(rho). When this result is taken together with the existing pvectorp parity violation data, the weak meson-nucleon coupling constants h(pp)(rho) and h(pp)(omega) can, for the first time, both be determined.