Himalayan-Tibetan plateau uplift drives divergence of polyploid poppies: Meconopsis Viguier (Papaveraceae).

Meconopsis Viguier (Papaveraceae) is an iconic genus of alpine forbs that includes medicinal and ornamental species. This study extends previous phylogenetic analyses of Meconopsis, using ITS sequences representing all the major Meconopsis clades. Phenotypic traits are also analysed for all described species. Our results show that Meconopsis evolved as a ≥ octaploid clade, with considerable interior structure reflecting further changes in ploidy levels as well as phenotypic differentiation. We support the exclusion of a few species as Cathcartia or Papaver, making Meconopsis a Tibetan region clade. Based on average rates of nucleotide substitution in angiosperm herbs we estimate that the Meconopsis clade diverged from the Meconella clade of Papaver approximately 16.6 Ma. This is soon after the 'hard' collision of the Indian continent with Asia caused uplift of the Himalaya and Hengduan ranges, greatly extended the Tibetan plateau, and initiated monsoonal climates. Eight major clades within Meconopsis are well supported and these correspond closely to previously recognised subgenus groups. However, the relationship among the clades is poorly resolved, probably because they diverged rapidly ∼15-11 Ma. Two of these clades are ∼dodecaploid but appear to have originated independently. The eight clades have distinct distributions, variously associated with the Himalaya, the eastern Plateau and Hengduan ranges. Some Meconopsis species were not monophyletic, suggesting that a combination of multilocus molecular and phenotypic traits is required when defining and revising species.

Impact of logging on aboveground biomass stocks in lowland rain forest, Papua New Guinea.

Greenhouse-gas emissions resulting from logging are poorly quantified across the tropics. There is a need for robust measurement of rain forest biomass and the impacts of logging from which carbon losses can be reliably estimated at regional and global scales. We used a modified Bitterlich plotless technique to measure aboveground live biomass at six unlogged and six logged rain forest areas (coupes) across two approximately 3000-ha regions at the Makapa concession in lowland Papua New Guinea. "Reduced-impact logging" is practiced at Makapa. We found the mean unlogged aboveground biomass in the two regions to be 192.96 +/- 4.44 Mg/ha and 252.92 +/- 7.00 Mg/ha (mean +/- SE), which was reduced by logging to 146.92 +/- 4.58 Mg/ha and 158.84 +/- 4.16, respectively. Killed biomass was not a fixed proportion, but varied with unlogged biomass, with 24% killed in the lower-biomass region, and 37% in the higher-biomass region. Across the two regions logging resulted in a mean aboveground carbon loss of 35 +/- 2.8 Mg/ha. The plotless technique proved efficient at estimating mean aboveground biomass and logging damage. We conclude that substantial bias is likely to occur within biomass estimates derived from single unreplicated plots.

Estimating rainforest biomass stocks and carbon loss from deforestation and degradation in Papua New Guinea 1972-2002: Best estimates, uncertainties and research needs.

Reduction of carbon emissions from tropical deforestation and forest degradation is being considered a cost-effective way of mitigating the impacts of global warming. If such reductions are to be implemented, accurate and repeatable measurements of forest cover change and biomass will be required. In Papua New Guinea (PNG), which has one of the world's largest remaining areas of tropical forest, we used the best available data to estimate rainforest carbon stocks, and emissions from deforestation and degradation. We collated all available PNG field measurements which could be used to estimate carbon stocks in logged and unlogged forest. We extrapolated these plot-level estimates across the forested landscape using high-resolution forest mapping. We found the best estimate of forest carbon stocks contained in logged and unlogged forest in 2002 to be 4770 Mt (+/-13%). Our best estimate of gross forest carbon released through deforestation and degradation between 1972 and 2002 was 1178 Mt (+/-18%). By applying a long-term forest change model, we estimated that the carbon loss resulting from deforestation and degradation in 2001 was 53 Mt (+/-18%), rising from 24 Mt (+/-15%) in 1972. Forty-one percent of 2001 emissions resulted from logging, rising from 21% in 1972. Reducing emissions from logging is therefore a priority for PNG. The large uncertainty in our estimates of carbon stocks and fluxes is primarily due to the dearth of field measurements in both logged and unlogged forest, and the lack of PNG logging damage studies. Research priorities for PNG to increase the accuracy of forest carbon stock assessments are the collection of field measurements in unlogged forest and more spatially explicit logging damage studies.

Combined effects of two arthropod herbivores and water stress on growth of Hypericum species.

The interaction between physiological stress and arthropod herbivory was studied using two perennial species of Hypericum. Seedlings of H. perforatum, a herb introduced to Australia and weedy in places, and H. gramineum, an indigenous species, were subjected to water stress and/or herbivory by a mite, Aculus hyperici and an aphid, Aphis chloris. Both arthropods have recently been released in Australia for biological control of H. perforatum. Individually, stresses reduced measures of plant growth. Combinations of the three stresses decreased plant growth by slightly more than the product of their separate effects, suggesting that there is a weak positive interaction exacerbating the damage caused by each stress. Seedlings of the target weed and the 'non-target' indigenous species were equally affected by the arthropods. The implications for weed biological control are discussed.

Factors affecting survival of tree seedlings in North Queensland rainforests.

Seedlings of six species of rainforest trees with widely constrasting ecology and seed morphology were transplanted at 3 weeks of age into tree-fall gaps and the shaded understoreys at two rainforest sites (Curtain Fig and Lamins Hill) on the Atherton Tableland, North Queensland, Australia. In each forest habitat, half of the transplanted seedlings were protected from vertebrates by means of wire cages, and survival was monitored over 16 months. The main objective was to estimate the extent to which independent variables (forest, habitat, protection from vertebrates, and species) contribute to explaining survival differences among the seedlings. Significant differences existed in the mortality among species, whether caged or uncaged. Seedlings unprotected from vertebrates suffered greater mortality (i.e. averaged over all species and forests, mortality > 75%), compared to the caged seedlings (mortality < 40%). Seedling of most species survived better in forest gaps, though the effects varied significantly among the six species. Survival of caged seedlings in Curtain Fig was significantly greater than in Lamins Hill, a pattern attributed to the partial deciduousness of the Curtain Fig forest. Because only few of the uncaged seedlings survived to 16 months, we focussed on the caged seedlings to examine the role of light at the forest habitats on survival. Relationship between seedling mortality and increasing light availability vary significantly among the six species. However across species, seedling mortality decreased linearly as photosynthetically active radiation (PAR) rose from 0.48 to 2.0%, after which an asymptote was reached and further increase in light (up to 8% PAR) did not influence survival significantly. Overall, temporal, species and the various environmental variables and their interactions explained about 60% of the variations in the seedling mortality data, with protection and species differences making the greatest contributions.