At the end of the day on Monday, as we finished up looking at and measuring trees in our plots, the 104-degree heat in the north coast interior was a bit distracting. But I noticed this guy growing on a black oak and wanted to take his picture (sorry for the blurriness) before he gets old and dried-out.
Most people interested in ecology already know this, but you can't mention it too often: some of the most valuable members of our forest communities are the ones that decay others, recycling nutrients through the greater ecosystem and basically cleaning up the messes--like accumulations of dead branches and trees that could serve as fuel for fires--attendant on the normal processes of animal and plant death.
Plus, fungi are simply interesting in their own right. They have myriad strategies for inhabiting and digesting other living and dead things, and they come in a variety of fascinating shapes and colors. Here is a mini-salute to some of the other decay fungi we sometimes come across in the Douglas-fir/hardwood forest up here in the north coast.
Unfortunately, some of the fungi that decay hardwoods are much more obvious now that P. ramorum has killed so many trees in our region.
On Friday, the San Francisco Chronicle published a story about Sudden Oak Death and the spread of P. ramorum in waterways. It mentioned that ten streams, ditches, or ponds in six states have now been found infested with P. ramorum. Many of these are states that are officially considered uninfested because the pathogen has not been found in the forest environment. In all these cases, the pathogen has been linked to nearby nurseries that have at one time or another carried infested ornamental plants.
The article points out that the most mysterious case is right here in Humboldt County. Two streams in McKinleyville, north of Arcata, are infested with P. ramorum. Although both streams run through heavily developed residential neighborhoods, we from UC Cooperative Extension have teamed up with Humboldt County Ag Department and Redwood National Park personnel to try to find the source of the spores in the stream by walking as much of the streambanks as possible to find symptomatic plants--and so far, we have found nothing in two seasons of looking.
Near both streams, there is very little host material for P. ramorum to infect. There are very few ornamental hosts and almost no bay or tanoak. The bright side may be that this paucity of host material means little chance of the pathogen's escaping the stream and spreading further. Another positive is that at the point where P. ramorum has been recovered in each stream, the waterways empty into the ocean in short order.
Although a nearby nursery in McKinleyville has had infected plants at various times in the past, there is no definite link between the nursery and the streams--the streams are too far away for water from the nursery to easily make its way to the streams--unlike in other states, where it's obvious how infested runoff exited each nursery and made its way to each nearby waterway.
The mysterious cases of persistent spores in these streams highlight the troubling difficulty of definitively ridding infested nurseries and forests of P. ramorum. 
Monitoring Rock Creek in Del Norte County for Phytophthora ramorum using rhododendron leaf baits.
On Friday, I was at the Trinity River in eastern Humboldt County, watching my son splash his way through water as clear as the sky above. One hundred feet upstream, a helicopter repeatedly dipped its bucket into the river, rising up each time to carry its load to one of the fourteen fires that broke out in our county and neighboring counties last week, the results of lightning strikes. As the helicopter passed over our heads, it trailed a stream of water from the bucket, and about three minutes later, it would be raining on us very gently for a minute or two.
This got me thinking, of course, about fire hazard and the toils of keeping cleared, defensible space around one's home when one lives in the country (which I do not). This in turn evoked thoughts of a local NGO in our north coast area, the Mattole Restoration Council (MRC), which is working to encourage homeowners in the Mattole River watershed to provide that defensible space by distributing grant money to help the homeowners get the work done. When each household maintains that magical 100-foot clearance, it benefits the entirety of this remote watershed, where it's often extremely difficult for firefighters to get quick entrance and egress on steep, narrow roads in scattered neighborhoods. With less flammable space around homes (and fewer homes that are themselves flammable--but that's another subject), firefighters can concentrate on attacking the flames in the wildland area rather than spending all their time worrying about defending structures.
This led to thoughts of other worthy MRC work: the organization is working on writing a Program Timberland Environmental Impact Report, a document designed to apply to owners throughout the watershed who want to practice sustainable forestry designed to return Mattole forestlands, many of which were highly degraded by mid-20th-century timber harvest practices, to healthy productivity while protecting water quality and other important values. Having a program document like this (i.e., an already-written "checklist"-type document) will make responsible forestry, which can be an expensive proposition for a small landowner, a real possibility for many watershed residents.
Which brought me to Sudden Oak Death. P. ramorum has moved to the very eastern edges of the Mattole River watershed. Soon, the disease could be one more thing for Mattole valley residents to worry about. Along with the MRC, UC Cooperative Extension has been holding informational workshops about SOD, but concern hasn't built as high here as in some areas of coastal California. This could partly be the result of a few dry years during which the pathogen has become less visible in southern Humboldt County because it has caused less tanoak mortality. On another level, though, it's understandable that many Mattole residents may have "wildland management fatigue" from worrying for so many years about fire, fish, and forestry.
Since Sudden Oak Death has not yet impacted the Mattole, there's a real chance that, given funding and political will, residents could do something the limit the spread throughout the watershed. But the disease is tagging along behind all those other equally important concerns. The question that occurs to me at this point, then, is this: Is there a way to unite these seemingly disparate domains? Given the realities of funding, in which each relatively narrow environmental issue attracts its own funding, scientific study, and advocacy groups, could some kind of comprehensive wildland management assistance ever materialize for rural landowners who need it, like the ones in the Mattole?
When our president talks about creating jobs to help our environment, this is what I see: an army of forest management experts and helpers, working in places like the Mattole to address all these wildland management concerns in a comprehensive manner. On any given property, these folks, organized into teams perhaps, would work on fuel hazard reduction and riparian restoration and erosion remediation and sustainable timber production and weed control and habitat protection and protection from insects and diseases. Considering how each of these management activities can often interact synergistically with the other activities, it remains a wonder to me that this hasn't already happened. It may just be that a vision like this, to come to fruition, will require a collective societal decision that wildland management is worth an investment.
The Mattole River: good for many uses.
I'll be upfront: I stole the title of this post from my supervisor at UC Extension in Eureka, Yana Valachovic, who also took the pictures. She has talked about this subject several times to various audiences, and I think it's so interesting I wanted to post it.
Below are two pictures of the same California bay laurel (Umbellularia californica) tree, one from a distance and one up close. Bay laurel (also called pepperwood, Oregon myrtlewood, or just plain bay) is the main transmitting host of Phytophthora ramorum. The pathogen produces loads of spores on the leaves of bay laurel, and the spores are then blown or splashed onto other trees. If those trees happen to be tanoaks, coast live oaks, Shreve oaks, California black oaks, or--maybe--canyon live oaks, they can be killed. (The bay laurels, meanwhile, remain completely unharmed.)
Because of this, some of the management activities aimed at controlling Sudden Oak Death focus on strategic removal of some bay laurels to reduce disease risks for particular important oaks and tanoaks. As part of our management experiments in the north coast, we decided to try cost-effective ways of killing large bay laurels. It's very expensive for crews to cut them down, remove the limbs, and burn the small limbs and foliage. So we decided to try girdling some trees to see how rapidly they would die in place. Even though the standing trunk and limbs would still be there, the foliage, which is the part of the tree that carries P. ramorum, would be gone.
To make a long story short: nothing doing. Those girdled bays are not interested in dying. The girdle on the tree below was made by one of the landowners with whom we are collaborating. And boy, did he ever girdle it! The "beaver cut" he made goes at least six inches deep into the sapwood.
The top picture gives you a good look at this beaver cut. But if you look at the bottom picture, you'll see that the tree is trying to heal itself.
The roughened area of bark-like tissue in the center of the trunk is an area where the tree is trying to grow a new "bridge" of cambial tissue over the girdled area to heal itself. The crown of this tree is still green and healthy-looking, over two years after it was girdled, despite the tree's inability to move food between crown and roots.
Obviously, bay laurels are amazingly resourceful trees! Maybe this is one reason why several ecologists have speculated that as tanoaks decline in coastal California because of the effects of Sudden Oak Death, bay laurels will increase in dominance in many areas.
My neighbor is re-doing a large part of the house she owns and rents out on our street. Her father, who left the house to her, had never been overly concerned with home maintenance, so when the previous tenant moved out, she decided to investigate the structure's health. What she found was discouraging. She estimates that if she hadn't intervened, the house would have collapsed because of rot in three or four years. She found dry rot in the framing, in the wood sheathing under all the windows, in various spots under the eaves--all around the place, in short. So she is replacing much of the framing and sheathing, has demolished the old carport, and is completely re-siding the house.
When I mention this to locals, they shake their heads and talk about how you really have to stay on top of "moisture management" around here. The north coast area sits where California's Mediterranean climate transitions into wetter Pacific Northwest conditions. Without adequate heating and ventilation, dry rot (the fungi Meruliporia incrassata and/or Serpula lacrymans) will attack even the wood in the highest portions of houses in this area--especially in post-war houses built mainly out of Douglas-fir.
And when I think of water and fungal organisms, I also think of water and Phytophthora. Phytophthora species aren't fungi, but they are very similar. The common name often used for them, "water mold," shows that they are even more dependent on water than fungi are. All Phytophthoras have a swimming stage, which Nicole has discussed before in her post on the amazing zoospore. Without the presence of standing water at some point in the year, Phytophthora reproduction and movement is impossible.
Many Phytophthora species like to hang out in free-flowing streams. If plants are infected with these Phytophthora species somewhere on the landscape, the zoospores will find their way somehow to the stream. From there, these zoospores can be baited out of the stream with rhododendron leaves or other plant parts that are suspended in the water column for a short period of time and then removed. The zoospores infect the leaves and cause lesions that can be plated in growth medium and examined under the microscope for presence of the particular Phytophthora species that caused them. This is one of our most reliable early detection techniques for the presence of P. ramorum in a landscape; often, we detect spores in the stream even before we have noticed tanoaks or true oaks dying in a particular watershed.
P. lateralis-killed Port Orford-cedar along the Sacramento River. Photo courtesy of Don Owen, California Dept of Forestry and Fire Protection
In contrast, no one fully understands the dynamics of P. ramorum in streams. These dynamics must surely vary from those of P. lateralis, since P. ramorum mostly does not infect roots. Is there a way for P. ramorum to escape the watercourse to infect upland plants, such as in floodwater or on animals? Or are the zoospores passively washed out to sea?
We do, however, understand that this issue carries implications for management of irrigation water in nurseries, since water drafted for irrigation can carry spores to the plants on which it lands (read examples of research here, here and here). Because of this, a good deal of effort has gone into investigating effective ways to filter nursery irrigation water and developing best management practices that emphasize ground-level, rather than overhead, irrigation. There is also an ongoing conversation about whether and how to treat water that is drafted to fight wildfires. This research and conversation adds yet another dimension to the concept of "moisture management" in coastal California.
