Large and Fine Scale Resiliency: Alder Disease in Alaska

Lori Trummer, USFSChrista Mulder, UAFBarbara Roy, U of OregonRoger Ruess, UAFGerald Adams, MSUGlen Stanosz, U of WisconsinLori Winton, USDAJennifer Rohrs-Richey

Alders (Alnus spp.)Alnus crispa (uplands)

Comments About Alders

Forest Service Investigating Dying AldersWed, April 29, 2009 Posted in Alaska News

For the past few years the U-S Forest Service has been investigating the cause of a massive die off of Alders across much of Alaska stretching from Nome down to Skagway.Mike Mason, KDLG - Dillingham

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Alaska Public Radio Network (APRN)

SoilNitrogenBank NWhy are alders essential to ecosystem health?N-fixing bacteriaN2

Dieback and MortalityChena River

Canker Fungi: Cytospora canker (Valsa melanodiscus)

Natural Injuries for Pathogen EntrySnow Loading

Colonization of Stem

Resilience on the Landscape

Fine scale resilience: Host control, physiologyResiliency: Large vs. fine scale

Large scale resilience: Location on the landscape (siltbar, stand density, age)Ecosystem resilience requires both large and fine scales

Physiological Damage to Alder

Local symptom with systemic affects

Pink healthy tissue

Tan dead tissue

Canker blocks water and nutrient transport

H2OCO2H2OCO2Leaf Surface: Strategy for Coping with StressOpenClosingOptimum: conserve water AND maintain positive carbon balance

Can we influence resilience at both of these levels?Can we reduce vulnerability (stresses)?

Degrading Resilience on the Landscape

Less destructive clearing practicesReducing Vulnerability to DiseaseHuman perception of alders works against maintaining resilienceHow to bring the social and ecological dynamics into conversation?

Research SupportThis research is supported by the Center for Global Change, Arctic Institute of North America, the U.S. Forest Service, and the Western Regional Center of the National Institute for Global Environmental Change.National Institute for Global Environmental ChangeU.S. Forest Service

Alder Physiology

2003200419302005Photo credit:Lori TrummerBeginMonitoringCytospora canker isolated

Valsa alnichecklistsTimeline2007Forest Health ReportExperimental Inoculations2006Generating working hypotheses about disease

Quantifying Fine-Scale ResilienceResearch Results:Water Loss Photosyntheis (Carbon Uptake)

AgendaCanker disease Fine-scale resilience in alders Disease on the landscape (Interior) Alders in Alaska

Clarify that this is disease is also called alder canker*Symbiotic association with bacteria that take atmospheric nitrogen and convert it to usable forms-available for plants. N is directly tied to the productivity of the system.*Answer these as they pop-up. Some things are easy to respond to No, alders are not weeds. Some things are harder to answer, in terms of how much weight they can hold. Sometimes, it just requires getting people to think a little bit outside the box of charismatic megafauna. If there are so many other cool things to study, what do those cool things eat? At some point in the food chain, alders come into play. And finally, a lot of people hate alders b/c they create a shrubby wall that makes charismatic megafauna hard to see. ***The affects of the disease may be as easy to see along river corridors, looking like a bunch of defoliated alders. Or, in thickets it might be a bit harder to see.*Give the audience some tools on how to ID this canker disease*If you see a lot of browse or physical damage, look for the pimply diffuse canker.*In either case, a new or progressed canker, you can peel back to bark to show dead vascular tissue *At the landscape scale, we can look at the extent of disease and postulate how the processes that operate at these larger scales may have contributed to high disease. So, at the landscape scale, resilience may just be a function of where you happen to be on the landscape. And, chance plays a big role in determining if you are exposed to things that make you vulnerable. For example, one hypothesis is that high density alder stands have high disease severity. Higher disease incidence and mortality have been found on the floodplain (it has also been more intensively surveyed, but this is the general consensus). SO, we have susceptible hosts in both uplands and floodplain. Why disease differences? There have been multiple proposed hypotheses such as temperature-induced drought stress, landscape processes, stand age and density. *Larger, landscape processes easier to see, and in a large part may be based on chance encounters, location on the landscape. But, given that plants are immoble, they have been forced, through extremely high selection pressure, to deal with stresses that they cant physically escape. This is what makes the study of disease more interesting than in humans, is b/c humans can use escape or avoidance in part to prevent sickness. So, the questions that I am interested in answering are how this disease affects the physiology of the host. 1. What type of damage does it cause. And the even more interesting question is 2. What type of adaptive behavior does it have in response to disease as a type of stress? But leaf level processes are also involved in resilience.

*Disease can affect every single plant process and plant system. While colonization of tissue may be local there are often systemic effects. (which can easily be measured at the leaf surface). Systemic affects involved lower water transport capacity, down-regulation in PS rate, changes in the light response of leaves. Adapted responses are controlled by an intricate system of biochemical responses and communication between the rest of the plant, involving biochemistry, hormone signalling. What adaptive response can easily be measured?**How do we influence these fine scale processes that the plant invests energy in or diverts energy to maintaining?*Resilience on the landscape is by chance. Just like if you are sitting on a park bench all day, and maybe a bunch of folks come by you who are sick or sneezes. But, those arent the only factors in disease development, just like those arent the only factors when you get sick. There are lots of other factors to take into consideration. For us.there may be things that make us more vulnerable to disease (stress, less sleep, poor nutrition, low immunitiy)******Taking these complexities at the landscape level, stepping them down to leaf level processes. Specify that I will be talking about resilience in the host, as pathogens can also be extremely resilient even more so than the hosts. The social aspects of this disease is really two-fold, and perhaps more. Humans can directly impact the disease cycle by causing massive landscape disturbances and also human attitude toward the disease. Alders dont produce beautiful flowers (roses, orchids) or yummy fruits (cran, blueberrries). Furthermore, they have this disease characterized as a canker. Most relate this to canker sore like in my mouth. *