drought stressThe phone has been ringing off the hook lately with calls from people describing sick and dying Douglas-fir and other conifer trees. The trees are of a wide range of ages and in many environments and settings, although most calls have been coming from within the valley margin and have to do with young trees.

So far, the answer is generally: “It is drought stress”.  Huh, in May? Well it has been a dry winter and spring, … but that is not the issue.

My best explanation is that we had a pretty hard end of summer last year. Remember that? NO rain until mid-October then, Boom, it was winter. By then, many trees had started running out of water, killing tops or branches, and leaving leaders and branches susceptible to attack by various opportunistic pests.

We started seeing a few classic signs of drought stress (tops dying and branches “flaring out”) at the very end of the season last year, but late enough that many did not have time to show up before the weather turned. Injuries had occurred, so it was just a matter of time before they expressed themselves, which is happening now. The recent hot weather seems to have made it more sudden and dramatic.

This happens from time to time. Here are two good articles a few years back by the ODF Forest Health team explaining Dead tops and Branches (with Good pictures), and about Drought and Mortality.

It is important to keep in mind that the Willamette Valley can be a challenging climate for trees. Many of our soils in the valley are poorly drained, which is hard on most of our conifers, and other soils are fairly shallow and cannot hold much water. Also our summers are hotter and drier than in the mountains. Heat and drought stress can kill trees outright, or more often just put the trees under stress, which can then lead to pest problems (as explained in the two publications above). From what I am seeing and hearing, the major cause of the problem now seems to be drought stress. Insect or diseases which able to take advantage of a stressed tree’s condition may sometimes be involved, but they are generally not the cause of the problems.

Finally, weather can be more stressful when trees are overcrowded, so thinning stands to keep trees vigorous with adequate growing space may be helpful in the long term. Right now, we just have to wait it out, and hope we get some serious rain this year, or we will see this problem intensify.

We all better get out there and wash the car…..

Brad Withrow-Robinson

I recently got a call from a guy selling some woodland property in the Coast Range. A prospective buyer recently told him that he had Swiss needle cast (SNC) and so was not interested in buying the property. It is not hard to find the disease in western Oregon. It is a native disease of Douglas-fir and is wide spread from the coast into the Cascades. But this fellow was calling for some guidance about how to respond to this concern. Was it reasonable? How can he gauge its impact on his young forest stand?

Phot credit: SNC Coop

He already knows how to recognize SNC when he sees it: from a distance it makes a tree look paleand sparse. This is because the fungus is developing in the needles, gradually clogging the stomates, which is where the leaf exchanges water vapor, carbon dioxide and oxygen. Up close with a hand lens you can look on the underside of a diseased needle and see tiny black dots in neat rows where healthy white dots (the stomates) should be visible. In some places or during seasons when the disease is severe, this causes many needles to turn yellow, and eventually to drop (to cast), giving the recognizable symptoms. If enough stomates get plugged, and or enough needles are cast the disease begins to affect photosynthesis, and possibly growth, the crux of the caller’s question.

“The key to understanding the impacts from Swiss needle cast,” says Dave Shaw, OSU Extension Forest Health Specialist and Director of the SNC Cooperative, “is whether the needle retention on the tree is good or not. If the tree is retaining around 3 years of needles, then growth should be close to normal. The impacts occur when needle retention is below three years, and especially when it drops to 2 years or less.”

Photo Credit: SNC Coop

So, the question for the caller is: “What is your average needle retention in these stands?” If near 3 years, he can tell folks that yeah, the disease is around but the stand is doing ok.

To count needle retention, use binoculars and cruise the stand, taking the needle retention from the mid crown, south side of tree, and not the apical stem, but the 4-yr and older side branches. There is a good illustration of branching and needle cohorts on page 3 of Swiss needle cast of Douglas-fir in Oregon. This time of year is good. Even if the stand is discolored a little, needle retention is the key factor.

More information about SNC can be found on the SNC Cooperative website, which has aerial survey data, research findings and even a Stand Assessment Tool that provides a more quantitative approach to assessing impacts on growth.

Brad Withrow-Robinson

Although a significant challenge, successful planting and establishment is of course only the first step towards restoring a forest. Moist tropical forests tend to have much higher tree species richness and diversity than do our temperate forests. While a forest in the Coast Range or Cascades of Oregon may have a dozen or so trees and shrubs (and is often dominated by just a few tree species) a similar area hill evergreen forest in Northern Thailand may have 100 to 150 species.
Replicating or recreating this diverse forest in one fell swoop at planting is impractical, or impossible. There are significant challenges of producing so many species in the nursery and also, many species seem poorly adapted to the harsh conditions of abandoned farm fields, and simply do not survive and prosper. Restoring a forest means restoring conditions and processes which in turn help create the forest.
After screening over 400 species, FORRU selected about 20 hardy species to plant as the “framework” for the future forest structure and processes. Species were selected according to their suitability to nursery production, survival and growth in abandoned field conditions, as well as to represent different growth forms and several successional stages. A great many of the selected framework species bear fruit, which is meant to encourage birds to visit the site in the hopes that they will carry in other native species. This is a key idea behind the framework species approach (adapted from Australia): along with changing the physical environment (light, leaf litter and organic matter) to favor establishment and survival of additional species, the planting needs to encourage mechanisms that deliver those species to the site. Initial findings are promising, with an increase in the number of birds and small mammals observed, and over 70 additional tree species recruited to the study plots.
But what will be the fate of those new seedlings? Does their presence today tell us what the future forest will be?
Most foresters and woodland owners in Oregon have seen a carpet of seedlings emerge on the forest floor following a thinning or other disturbance that lets more light reach the ground and maybe exposes some soil. Douglas-fir, grand fir, hemlock, alder and maple may all show up in abundance. Familiarity with our local species tell us that the fate of these seedlings is not the same. Douglas-fir generally will not grow to maturity in those conditions, while the hemlock or maple might.
Hathai (my graduate student) is trying to develop a similar understanding of the trees which make up the hill evergreen forests in Thailand. Her work on the regeneration dynamics of trees in the understory should help people here in Thailand have a better idea of the likely fate of the seedlings, and if their arrival heralds development of more complex and diverse forests in the future. Her work may also suggest ways to manage the plantings to best meet the restoration/management goals.

 

Brad Withrow-Robinson

If you have called or emailed me recently, you have received an “out of office” message saying I would be away in February. The full story is that I am in the mountains of Northern Thailand, helping my graduate student, Hathai, with her dissertation research on forest regeneration dynamics of understory trees. Her work is part of a bigger effort at Chiang Mai University (CMU) to study how to restore diverse, seasonally-dry tropical forests.
Thailand has lost over half its forest areas in the last 40 years to unsustainable timber harvest practices and land use conversion. In the mountains of Northern Thailand, most forest loss and degradation is driven by a history of shifting agriculture. Abandoned after farming, much of this land becomes dominated by aggressive invasive perennial weeds which prevent forest regeneration both by directly competing with seedlings and also by feeding widespread fires each dry season (March-May). These fires are not part of the natural fire regime, but are human-origin fires that kill many of the young seedlings getting established naturally, or as part of planting efforts. This favors and perpetuates the weed communities rather than native forests.
The Forest Restoration Research Unit (FORRU) at CMU has been working on this restoration challenge for the past two decades. The FORRU team began their work with basic research on local forest trees, studying life cycles, flowering and fruiting phenology. Likewise, they tackled challenges in nursery production by testing germination and nursery cultural requirements to help them grow and plant viable seedlings. All very much as was done in the Oregon four or five decades ago.
Success in the field came by both controlling the weeds in the plantations for several years after planting (no surprise to us in Oregon) and very importantly, through rigorous and on-going community-level fire suppression.

 


This work has paid off, and they have made great progress in learning how to begin to put forests back on the landscape.

Brad Withrow-Robinson

Planting trees is a central part of woodland ownership. For many folks, planting was the first thing they had to do upon buying cut-over land. For others, it is part of leaving things better than they found them, of leaving a legacy or creating opportunities for the next generation.

Planting is a critical step towards growing a new forest, whether you are reforesting a harvested unit, or converting pasture or other farm ground to a riparian buffer. But it is not the first step in the process. That began a year or more ago with a look at the ground to decide what to plant and how to prepare the site. It continued with the work done to be ready to plant, and will go on a few more years after the seedlings are in the ground. At each step, in each season, success comes from focusing on the task at hand.

I was reminded of this when I was out visiting Bob Feldman last month. Bob and his family tend about 350 acres of conifers, oak woodlands and Christmas trees in the Eola Hills northwest of Salem in Polk County.

We walked down the hill to a 6 acre clear cut he harvested last summer. Before the logger left with his equipment, Bob had him deck some logs for firewood and pile the excess slash for burning. The site looks great, ready to plant.

So now Bob is ready to go with his ground ready, 2-0 seedlings ordered and planting crew lined up. After picking them up from the nursery, he will store his seedlings in a local cooler, pulling out a day’s-worth at a time to keep them in the best condition possible.

Bob stressed the importance of lining up a good contractor, someone with experience and a record of success they can demonstrate. Be sure to oversee their work, establish accountability and to make sure they do a good job. How? Get out there with them. Spend a good part of the first day with them, and a little time each day after that. Make sure you have explained how you want the job done, and to show that you care that it is done right. Check to see that things are being planted at the agreed spacing. Dig up a few seedlings to see that they are planted correctly, snug, at the right depth and not J-rooted. Check across the planting crew, and bring concerns to the crew leader. When finished, go out and look to see if you got what you asked for.

Good advice. But what if you are the leader, and the crew is your family? Bob has lots of experience there too, and says if they are new to it, then you have to teach them how to do it right. Stay with them and supervise until they get the hang of it. If adults, they should be as interested is getting it done right as you. If kids, their interests are a bit more complicated. Be patient with kids. As important as it is, you are teaching them more than “green side up, brown side down.” You are teaching them how to grow a new forest.

Brad Withrow-Robinson

Brad Withrow-Robinson, Forestry & Natural Resources Extension Agent for Benton, Linn and Polk Counties.

 

Let me begin by saying that I am a Luddite.  I am not the first among my family or peers to embrace new technologies.  I was deeply suspicious of computers, even while my brother carried around stacks of punch cards in high school.  I am nostalgic for analog cell phones, laying  quietly in a bag in the car, unable to play music,  but able to beam a call from way up the Santiam canyon, or pick one up anywhere along Hwy 99 in Polk County!  I could probably have direct dialed the Space Station.    

My cell phone is dumb.  I don’t tweet on Twitter, and I know where all my friends live.

But even a reluctant old dog can learn new tricks.  So when  Amy and I were talking about finding  ways to work together more, she suggested I contribute to the blog.    So I signed up for a test drive.

Expect to see articles from me from time to time.  I’ll cover a range of topics as well as touching on a couple recurring themes,  like “Growing a New Forest”.  I hope to bring you wisdom from some experienced woodland owners and foresters in our area, while covering some of the new science or past discoveries that are the underpinnings of forest management.

But I just thought I ought to set the record straight now.  I am bound to leave the blinker on (or at least the blog-equivalent),  so when it happens,  you’ll know who is at the wheel.