#ecounite

Date: May 21, 2015

Location: Green Dragon Barrel Room

Speakers: Kate Holleran-Natural Resource Scientist, Metro;

Mart Hughes—Natural Resource Ecologist, City of Portland

SUMMARY

Kate and Mart each presented data and examples of managing for climate change in Portland, and an in-depth group discussion with difficult questions following each. Kate presented on the challenges of managing secondary forests in the face of climate change and explained several examples. She noted that many of the practices of managing for healthy, resilient, resistant forests are good practices for managing for climate change as well, and that we might need to start thinking more about sources of restoration material. Mart presented on a study that he conducted on the likely impact of climate change on upland vegetation communities. He put our current vegetation communities in context by showing that they haven’t been around all that long. He showed that we are on the dry side for most of our communities, and with decreased available water during the growing season, they could easily switch to scrub/shrub or open oak/madrone forests with increased summer drought. Details of restoration practices, such as planting densities and ratios of trees to shrubs were discussed. Mart created a table that shows likely “winners” and “losers” for climate change looking at plant physiology. A general statement was made that we should be managing for vegetation community goals with a “side eye” for climate change. Issues surrounding the possibility of assisted migration were raised, which will be the topic of our next meeting.

Notes:

Kate’s presentation:

Metro has preserved a lot of land in Portland and Gresham, which is a good first step for resistance/resilience to climate change because it preserves places and corridors; this can help address the increasing threats of fire, insect pests, and droughts

Many of the forests in this area are former commercial tree farms with few snags, little downed wood, and very simple structure with trees mostly of the same age and size

Managing for healthy, resilient, and resistant forests provides many of the things that we would be looking for in managing for climate change:

-reduce fragmentation and maintain corridors

-understand where growers are getting their stock; we are in a large seed zone

-density management (i.e. thinning); this would happen on its own in 200 years, but we can help it along

-conserve and increase biodiversity at all scales

-monitor and control invasive species

Metro is thinning to reach increased diversity; the priorities for fate of thinning wood are (in order): leave on site, use in restoration of another site, send to mill

Oak/madrone release has occurred on Chehalem ridge after Douglas fir thinning

Metro is thinning McCarthy Creek just north of Forest Park; for most of the area there is a “light touch”,

but there is heavier thinning in riparian and areas planned as a reserve with the hope that they don’t have to come back and do more thinning later

They are faced with the question of what to underplant and where the seed source should be

For forest management, climate change is not much of a stretch from healthy forest management with consideration of seed source

Aspen is native to Oregon but not to Johnson Creek, but it might get planted there due to the projected climate

At Scouter’s Mountain there are a few old growth Douglas firs and lots of young Douglas firs because of lack of fire after Native Americans were pushed out; how do we manage that system?

Audience comment that there seem to be a lot of things that we should do that we don’t do for political reasons; when do you do what’s right and face the blowback? Picking battles and bringing the public along can be very important for successful projects

The variable forest densities of the past provided natural fire breaks

Our near-future fire regime is likely to be stand-replacing fires

Mart’s presentation:

Mart presented on a study that he conducted on the likely impact of climate change on upland vegetation communities

With the predicted 2*C increase in temperature, it is likely that our region will have less moisture in the growing season than it currently does

There is currently ~2*C temperature difference in Portland where it is ~2*C cooler in Forest Park than along the Willamette

Now winter starts ~October 15th, and summer starts sometime between January and June; most of the water that falls during the winter is outside of the growing season and does nothing for plant growth

Ephemeral streams dry around April/June, and many plants live on soil moisture from then on

Predicted changes show less summer precipitation and less snow that could melt in the summer, leaving upland plants with less moisture during the growing season

The Whitaker Diagram shows global vegetation types as a function temperature and precipitation; Portland woodland is currently near the verge of scrub/shrub, and with increased temperature and decreased precipitation, it could move there

The vegetation communities that we are used to around here can exist where it is cooler and wetter than here

The soils here can make plants more prone to drought stress

Douglas fir and big leaf maple are dominant species in the uplands now

We are currently on the dry side to Douglas fir, so it will likely be more stressed with climate change

Plant populations generally have a standard distribution in relation to environmental conditions

Graph that depicted upland forest species that would likely do well and poorly with predicted climate change based on physiology

In general north-facing slopes are more “secure” against climate change than south-facing slopes

Portland is at the “bottom of the bowl” in terms of elevation in the area, so to look for something lower than here, we have to travel down to Redding, CA

Open madrone/Douglas fir/oak forests might be our future model; they are more fire adapted

We can look at San Juan Islands and Elk Rock Island for a future model

Prunus emarginata is likely good in future climate, and it is good for bugs, which means it is good for migratory birds

There have been times (e.g. 5,000 years ago) where it was drier here than it will likely be with climate change, so we can look at pollen from those times and see what was here

There was a sudden change here 10,000 years ago from taiga to hardwood forest that we can see in the pollen record; so our current system is not that old

 Forest Service paper GTR 841 has information on forests in the Olympic Peninsula

Possible savannas in Portland’s future

Hardwood trees are good for migratory birds because the birds need bugs and 90% of bugs are on hardwood rather than conifer trees

One possible adaptation policy can be to plant a greater variety of plants and see what survives; this has been working well for street trees

Restoration plantings are often dense, and it can be difficult to get approval to thin later when needed

Many disturbed sites already have a canopy, and the work is to encourage shrubs

Suggestion of a 1:10 or 1:15 ration of planting trees to shrubs in the non-critical riparian area

Suggestion to have community goals with a side eye for climate change

Figures are from Mart's presentation.  The species forecast is based on the median annual precipitation of the current species range, and forecasting that against Portland's median precipitation.  Also, because it will get warmer (but maybe not drier on average), there will be reduced soil-water availability during the summer months.