Monitoring whitebark pine stand health in the central Washington Cascades

Whitebark pine (Pinus albicaulis) plays a vital role in colonizing newly disturbed areas, providing shade for other tree species to germinate, and supplying food for a variety of birds and mammals, such as Clark’s Nutcrackers (Nucifraga columbiana) and grizzly bears (Ursus arctos horribilis). Decline of whitebark pine populations has been attributed to several factors, including white pine blister rust (Cronartium ribicola), mountain pine beetle (Dendroctonus ponderosae) outbreaks, and fire exclusion. In 2009, the U.S. Forest Service began to install permanent plots in whitebark pine stands in Washington and Oregon as part of a Pacific Northwest restoration strategy to track blister rust and mountain pine beetle mortality. Forest Service crews conducted surveys on these plots that included standard tree inventory measurements and assessments of blister rust, mountain pine beetle, and fire activity. During summer 2020/2021, we remeasured 12 of these plots located in 3 areas of the Okanogan–Wenatchee National Forest (Mission Ridge, Clover Springs, and Lake Ann) and 1 area within the Ahtanum State Forest (Darland Mountain). On average, 15% of trees were newly infected by blister rust, 5% of trees died from blister rust, and 12.6% died from all causes combined in the 11–12 years between surveys. Despite this, the density of live whitebark pine trees experienced a nonsignificant increase due to regeneration, while the density of whitebark pine snags increased significantly and the density of whitebark pine seedlings decreased significantly. The percentages of trees with blister rust infection, seedlings with blister rust infection, and live trees with mountain pine beetle damage were heterogeneous over space and time. Our results help quantify parameters that are central to understanding the population dynamics of whitebark pine in the Pacific Northwest and informing management decisions, but the findings should be interpreted in light of the limited sample size and spatial extent of our data. Regular monitoring of a wider array of permanent whitebark pine plots will be critical to management of this tree species

Wiring of Photosystem II to Hydrogenase for Photoelectrochemical Water Splitting.

In natural photosynthesis, light is used for the production of chemical energy carriers to fuel biological activity. The re-engineering of natural photosynthetic pathways can provide inspiration for sustainable fuel production and insights for understanding the process itself. Here, we employ a semiartificial approach to study photobiological water splitting via a pathway unavailable to nature: the direct coupling of the water oxidation enzyme, photosystem II, to the H2 evolving enzyme, hydrogenase. Essential to this approach is the integration of the isolated enzymes into the artificial circuit of a photoelectrochemical cell. We therefore developed a tailor-made hierarchically structured indium-tin oxide electrode that gives rise to the excellent integration of both photosystem II and hydrogenase for performing the anodic and cathodic half-reactions, respectively. When connected together with the aid of an applied bias, the semiartificial cell demonstrated quantitative electron flow from photosystem II to the hydrogenase with the production of H2 and O2 being in the expected two-to-one ratio and a light-to-hydrogen conversion efficiency of 5.4% under low-intensity red-light irradiation. We thereby demonstrate efficient light-driven water splitting using a pathway inaccessible to biology and report on a widely applicable in vitro platform for the controlled coupling of enzymatic redox processes to meaningfully study photocatalytic reactions.This work was supported by the U.K. Engineering and Physical Sciences Research Council (EP/H00338X/2 to E.R. and EP/G037221/1, nanoDTC, to D.M.), the UK Biology and Biotechnological Sciences Research Council (BB/K002627/1 to A.W.R. and BB/K010220/1 to E.R.), a Marie Curie Intra-European Fellowship (PIEF-GA-2013-625034 to C.Y.L), a Marie Curie International Incoming Fellowship (PIIF-GA-2012-328085 RPSII to J.J.Z) and the CEA and the CNRS (to J.C.F.C.). A.W.R. holds a Wolfson Merit Award from the Royal Society.This is the final version of the article. It first appeared from ACS Publications via http://dx.doi.org/10.1021/jacs.5b0373