Optimal stomatal theory predicts CO responses of stomatal conductance in both gymnosperm and angiosperm trees.

Optimal stomatal theory predicts that stomata operate to maximise photosynthesis (A ) and minimise transpirational water loss to achieve optimal intrinsic water-use efficiency (iWUE). We tested whether this theory can predict stomatal responses to elevated atmospheric CO (eCO ), and whether it can capture differences in responsiveness among woody plant functional types (PFTs). We conducted a meta-analysis of tree studies of the effect of eCO on iWUE and its components A and stomatal conductance (g ).

No carbon limitation after lower crown loss in Pinus radiata.

Background And Aims: Biotic and abiotic stressors can cause different defoliation patterns within trees. Foliar pathogens of conifers commonly prefer older needles and infection with defoliation that progresses from the bottom crown to the top. The functional role of the lower crown of trees is a key question to address the impact of defoliation caused by foliar pathogens.

Contrasting the Pathogen Loads in Co-Existing Populations of and in Douglas Fir Plantations in New Zealand and the Pacific Northwest United States.

The emergence of as a foliar pathogen of Douglas fir in New Zealand and the Pacific Northwest United States has raised questions about its interaction with the widespread Swiss needle cast (SNC) disease. During Spring 2017, we repeatedly sampled 30 trees along an environmental gradient in each region and 292 additional trees in a longitudinal transect to assess the epidemic and the association between and , which are causal agents of SNC. Both pathogens were consistently more abundant in the host's exotic environment in New Zealand.

Modelling the key drivers of an aerial Phytophthora foliar disease epidemic, from the needles to the whole plant.

Understanding the epidemiology of infectious diseases in a host population is a major challenge in forestry. Radiata pine plantations in New Zealand are impacted by a foliar disease, red needle cast (RNC), caused by Phytophthora pluvialis. This pathogen is dispersed by water splash with polycyclic infection affecting the lower part of the tree canopy.

Phytophthora pluvialis Studies on Douglas-fir Require Swiss Needle Cast Suppression.

Phytophthora pluvialis is associated with early defoliation and shoot dieback in Douglas-fir in Oregon and New Zealand. In 2013, P. pluvialis was described from mixed tanoak-Douglas-fir forests in the Pacific Northwest and concurrently recognized as the main causal agent of red needle cast (RNC) in New Zealand radiata pine plantations.

Foliar phosphite application has minor phytotoxic impacts across a diverse range of conifers and woody angiosperms.

Phytophthora plant pathogens cause tremendous damage in planted and natural systems worldwide. Phosphite is one of the only effective chemicals to control broad-scale Phytophthora disease. Little work has been done on the phytotoxic effects of phosphite application on plant communities especially in combination with plant physiological impacts.

Sustained enhancement of photosynthesis in mature deciduous forest trees after 8 years of free air CO(2) enrichment.

Carbon uptake by forests constitutes half of the planet's terrestrial net primary production; therefore, photosynthetic responses of trees to rising atmospheric CO(2) are critical to understanding the future global carbon cycle. At the Swiss Canopy Crane, we investigated gas exchange characteristics and leaf traits in five deciduous tree species during their eighth growing season under free air carbon dioxide enrichment in a 35-m tall, ca. 100-year-old mixed forest.