Current Research Projects in the Jules Lab
Whitebark pine in the Cascades
The forests of western North America face a number of significant and ongoing changes, including the impacts of an increasing number of non-native diseases, elevated levels of insect outbreaks, and notable changes due to fire suppression. In the Cascades, one species -- whitebark pine -- stands as the icon of high-elevation plant communities and is well-known to any hiker that has reached treeline. Whitebark pine plays critical roles slowing snowmelt, modulating hydrological systems, and providing surprisingly large quantities of food resources for wildlife. Currently, whitebark pine is declining due to (1) the exotic white pine blister rust, (2) mountain pine beetle outbreaks (3) fire suppression and, potentially, (4) climate change. In collaboration with the Inventory & Monitoring Program of the National Parks, I have recently begun a three-year study in Crater Lake and Lassen National Parks aimed at establishing long-term demographic monitoring plots. My ultimate goal is to collect enough long-term data to build rigorous models of population dynamics (i.e., matrix projections) that will help better estimate the rate of decline, and also determine the efficacy we must approach in our efforts to outplant genetically resistant pine seedlings.
Invasion Ecology/Port Orford cedar:
This research concerns the factors that govern the rate and extent of 'biological invasions'. To date, our ability to ascribe general rules to the invasion process has been limited by a lack of detailed data on spread history coupled (simultaneously) with measures of important ecological features across the invasion landscape. To approach this issue, I study Port Orford cedar, a conifer endemic to northwest California and southwest Oregon. In 1952, a fatal, non-native root rot disease was accidentally introduced into the range of the cedar and has since been spreading rapidly. In my study, I have reconstructed the spread of the disease across a focal area in southwestern Oregon where I have measures of host and landscape characteristics at every potential infection site. This research is being conducted with Matt Kauffman of University of California, Santa Cruz.
Detecting change in subalpine forests
This project involves resampling >200 subalpine forest plots established in 1969 in the Klamath Mountains of CA, specifically the Russian Wilderness. After the first field season, we are detecting changes in forest composition that appear to be related to elevation. While the analysis is still underway, our most important result is an increase in red fir (Abies magnifica var. shastensis) mortality, which we can generally attribute to a complex array of factors such as dwarf mistletoe (Arceuthobium spp.), Cytospora cankers, Annosus root disease (Heterobasidion annosum), Armillaria root disease (Armillaria ostoyae) and fir engraver beetle (Scolytus ventralis). In the next few years, we will focus on more detailed assessments of the causes of fir mortality; we suspect the bulk of mortality is due to decreased snowpack levels increasing beetle populations.
Darlingtonia nd Fire:
The carnivorous Darlingtonia californica (California pitcher plant) is the dominant plant in uncommon wetlands of northern California and southwestern Oregon. Found on serpentine geology, these wetlands (fens) support a unique plant community that includes several rare taxa. Fire is the most common disturbance in these wetlands, though virtually nothing is known about how plants respond to fire in the fens. I have an ongoing collaborative project assessing the role of fire in these communities.
Diversity in Logging Areas/Chronosequence Study:
The ability of understory plants (e.g., herbs) to recover after a logging event is poorly understood. The importance of this kind of information, however, is great, especially if managers are to develop strategies to maintain a diversity of species across forested landscapes. I have developed a chronosequence of forests in the Siskiyou Mountains of southwestern Oregon to assess the response of understory plants to clearcut harvesting. This chronosequence is a series of forest stands that range in age from 2 years (a clearcut) to 430 years (an old forest).
Plant Demography:
Demographic studies of rare and invasive species are vital for understanding how to best manage for reduced or increased population growth rates. Frequently, demographic studies can reveal aspects of populations that are not intuitive, and which point to management strategies that otherwise might not have been considered. I am currently initiating long-term demographic studies on several plants. In one study, I am assessing the viability of trillium populations in logged and old-growth forests of southwestern Oregon. I am interested in both the effects of population isolation in old-growth fragments and the factors limiting recovery in recent clearcuts. I am also involved in using long-term demographic data on the endangered Humboldt Bay wallflower to understand the influence of disease on population dynamics.