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Tuesday, December 31, 2013

What Trees Should We Cut?

First, some rules of thumb:

Easy decision: In a real prairie, cut all trees. Prairie can’t grow under trees. No real tree is truly happy degrading a prairie.

Medium decision: In an overgrown but original savanna, cut enough trees of all kinds to get enough sun for enough grass for regular grassland burns. Probably best to cut some of all tree species, but try to save many young examples of the oak species best represented among the site’s oldest trees. On a small site, it may be necessary to remove almost all fire-sensitive and aggressive species, such as maples, red cedars, basswoods, ashes, etc. to allow enough sunlight to grow grasses for fuel and re-establish a natural burn regime.

Hard decision: In an oak woodland, our burns will probably not be severe enough, under today’s controlled conditions, to kill mature invading trees. Thus we have to make hard choices. However unqualified and humble we are, there’s no alternative. If we want to conserve the vanishing oak woods biodiversity, we have to perform some "first aid" to save the species and re-establish natural processes. Then, in the longer run, we can hope that nature (including fire) will be able to make its own decisions.  

Consider the degraded oak woodland shown below. Judging from the oldest trees (some of which predate Euro-american settlement by more than a century) the “original” dominant trees here were bur and white oak.  Thus probably most of the biota that need conserving here (e.g. invertebrates, fungi, bacteria) is part of an ecosystem sunny enough for reproduction of bur and white oaks.

What gets cut? First, of course, all the buckthorn (still green in this photo). Second, we’d cut at least 90% of the shadiest invaders including maple and basswood (yellowish wide leaves on the right).

We spare some elm in the wettest areas, where all the big elms seem to be. We cut most of the big cherry (which one study found to be the most invasive canopy tree of the region’s oak woodlands). Box elder mostly goes. We stopped cutting large ash years ago, because they’ll all die soon of the emerald borer. But little ash won’t succumb to the borer for many years, and they make as much shade as buckthorn – so we cut the little and pole ash.

Some people are surprised by the oaks we cut. See that skinny pole tree on the far left – the dark-barked, branchless, youngster with its top already in the canopy? That’s a red oak. They’re fast growing and survive a lot of shade. Yes, they’re oaks, which some people assume makes them holy. But after cherry, they’re often the major pest in a long-unburned bur or white oak woods. Neither bur nor white can grow under the dense shade of red oaks. We usually don’t cut the big ones (good idea? bad idea?), but the pole reds go into the bonfire with the buckthorn.

Nor do we seek to make the woods uniform. Especially in bur oak woods and savanna, trees on the original landscape were highly clumped. As a result, woodland plants (and some animals) occupied the darker areas; distinctive savanna species thrived in moderate light conditions; and many prairie species lived in the parts with the fewest trees. This kind of diversity is way more complicated than we could make detailed plans for. But if we restore basic structure and processes (including fire and seed dispersal), the rest of the biodiversity can compete and evolve its way to rich resurgence.

Artificial edges are also special cases. As Joe Neumann put it, "Much of my tree thinning targets the edge where an oak woodland opens into a field. Black oaks fill in this border much more aggressively than other oak species. I remove about half of the black oaks. More can be removed later if necessary. I do't focus on the outer trees, since they are generally more open-grown and healthy. I create a savanna strip that boosts light levels and allows more wind to penetrate the interior. This should increase the intensity of the landscape fires so that over the longer-term, a healthier understory can develop along with a less crowded, new generation of oaks."

In this second photo, we’re looking at a bur and scarlet oak woodland that’s been burned for 28 years. The buckthorn was everywhere as dense as it still is along the edge (the dark green slash across the middle of the photo). We left all the “native” trees when we burned (top-killed) the buckthorn and herbicided its re-sprouts.

Is what we have here now healthy enough? The three big trees are bur oaks. But there are no sapling bur oaks in the grove (although there are hundreds where sunlight is ample, around the edges). The pole trees in the grove are red oak, cherry, hickory, and basswood. Should we have cut some of them earlier? Probably. Should we cut some now, so we don’t end up with a bizarre forest of shade survivors? Yes, it seems about time.

Your comments are very welcome.


But one little added note on the herbs, for those interested. The main species visible in the photo above (if you blow it up) are elm-leaved and blue-stemmed goldenrod, wild coffee, purple Joe-pye-weed, and a little bit of rue anemone. This 5-acre prairie grove has more than 25 species of sedges and grasses and more than 100 species of woodland wildflowers. Many rare butterflies and mushrooms have been found. It’s off to a good start, I mean recovery.  

CREDITS: Thanks to Joe Neumann, Pete Jackson and Jeff Weisz for helpful edits and additions.


  1. It can be difficult to decide among some native tree species as to which should stay and which should go. But I have found that to best reach your desired plant community state, one has to “steel” himself and remove most of the native species that are not part of the plant community that you are trying to restore. However, I always try to leave a few in order to add diversity as long as they do not significantly interfere with conservative members of the desired plant community or any of the key ecological processes (fire behavior for example). These can be hard decisions (removing native species from a plant community of which they do not historically belong), but unfortunately they can get even harder when deciding how to manage an ecological community that has members (species that historically belong in the community) with conflicting management needs.

    1. In a way, most species have "conflicting management needs." Some thrive best with early burns, or late burns, or spring burns, or fall burns, or rotating burns, or no burns (to say nothing about different regimes of competition, deer population levels, presence or absence of top predators, etc.). Part of our job is figuring out the balance. Part of the balance may be having very different management regimes spread over many different sites.

  2. Could this be retitled as Chainsaw in Lieu of Absence of Fire? When my lot was cleared of buckthorn I was amazed to see all the spring ephemerals and other natives pop up that were in a seed bank adjacent to a forest preserve. It was great fun for me and my daughter to then plant and nurse an Iowa crabapple. But no white oak or burr oaks germinated. After the buckthorn was cleared the ashes were taken out. Some Smilax and doll's eyes came up, but no white or burr oaks. Then I dropped the basswoods but still no white or burr oaks. There are oaks, all red oaks just like you describe above, 25 on 1/16th of an acre! Just north of these red oaks in the forest preserve I count TEN dead white oaks on the ground and a struggling burr oak. Those 25 red oaks I hope are the last layer of drapery. In the last ten years on an almost yearly basis what I thought was sufficient clearing became insufficient as far as "preserving" the natural landscape with white and burr oak regeneration occurring. Not only do the species have conflicting needs, but as you imply the different sites and niches have different ecological needs. It's critical that someone with experience and understanding who cares, Stephen Packard, is listened to. I may end up leaving just one red oak, but someday I hope some white and burr oaks will pop up.

    1. Paul, thanks for the compelling description of your good work. It has been impressive to see all the rare and endangered herbs increasing in your now less-dark woods oak woods.

  3. Stephen, Sometimes I think good silvicultural practices are what we need in our forest preserves. The only way you are going to get enough light for burr oak regeneration is to cut some of those old burr oaks. If sustainable harvest will help balance the shifting dynamic of grassland to woodland then maybe this is what should be done. It just must be done carefully, with a small fraction of work occurring in any given year, with specific set goals, and a review of results to make sure the goals are achieved.

    This being said, I do not enjoy cutting native trees. I have seen quality mesic woodlands become filled with non-conservative native species after all trees but burr oaks were cut. This is tough to watch, even if it ends up being temporary. I helped clear maples from a small area of an oak woodland and have noticed little difference in the vegetation since that day of cutting. Some of the native woodland grasses did begin to set fruit after the maples were removed, but the change over the years did not strike me as being significant. Every year I check and I have yet to observe Lonicera prolifera bloom in this area.

    In another area we cleared all the invasive species under a grove of walnut trees adjacent to an open habitat with rare species. We discussed whether we should ask the FPD to remove the nearly mature walnut trees. After removing the invasive species, nothing significant was growing under the walnut trees. My thought was the trees should be removed when they were ready for harvest and at that point the efforts to expand the rare species in the area should proceed. It just would not make sense to cut down trees that are worth so much money and burn them in a brush pile.

    Have you considered that the harvest of mature burr or white oak trees might be necessary to achieve your goals?



    1. Cut mature bur or white oaks? It may depend on what you mean by "mature." In many places the very old oaks are widely spaced. "Mature" younger pole oaks are sometimes much denser than the 1800s surveys showed. I can imagine strong arguments being made in favor of girdling some of them.

    2. Stephen, I think the more dense young stands of burr and white oak create a different habitat type that is preferred by different species. I would leave the dense stands of young trees alone because these locations of strong white and burr oak reproduction are currently not very common. Over time a "king of the mountain" will arise and these stands will thin into a more open stand. Our oak trees seem to all be really old and not be reproducing. I think if some of the old trees were harvested then the dense young tree habitat type would become more common. If we continue to cut all trees but burr and white oak, then we will end up with one habitat type and less diversity. If we harvest the mature trees, then we will have a variety of species age classes, fire intensities, and habitat types resulting in more diversity.

      As for the wolf oak trees that often manage to survive in prairies 50 yards or more from the woodland edge, I would leave them alone. There are not many of these trees and I think they are worth saving. They also make a nice place to have a snack after working all morning in the hot sun.



    3. Stephen,

      Your blog made me look through a small book I acquired in college called “Woodlands and Wildlife.” This book is published by Penn State. The following is from the chapter Managing Major Forest Habitats, Mature Woodlands, pp. 28.

      Quality of mature woodland for wildlife depends on several factors, the most basic being forest type. The two forest types that are more common in Pennsylvania are mixed oak, which occurs in the southern two-thirds of the state, and northern hardwoods or beech-birch-maple, common in the northern third of the state.
      One important difference between the two forest types is food production. In the oak type, all the oaks as well as hickories and occasional beech or walnut, may produce mast. In northern hardwoods mast is produced by cherry, beech, and an occasional oak or hickory; however, beech produces a good nut crop only occasionally. The management of a woodland should be designed to insure a continuing supply of vigorous 40- to 80-year-old mast-producing trees of several different species. A stand composed of different species usually not result in a total mast failure for the year.

      For example, suppose weather for acorn development is good one spring but bad the following spring. There will be no white oak acorns the year of adverse weather since white oak acorns develop in one year, but you will have a good crop of red and black oak acorns from the previous year since these take two growing seasons to fully develop. With only white oaks in your woodland there would have been no mast production in the year of bad weather. If your woodland contained only red or black oaks, there would be no acorns the second year following the adverse weather.
      Insects or diseases frequently attack only a certain species of tree. Consequently, a mixture of mast-producing trees tends to be more reliable as a source of food for wildlife.

      It then goes on to talk about timber stand improvement and leaving den trees.



  4. They agony of decisions!

    I could see a site manager deciding to remove some canopy bur or white oaks in order to open up some ground space. Some things to consider may be? Does the removal of the trees adversely affect fire behavior? Are the trees selected to be removed non mast producing? Are there desirable indicator species present in the herbaceous layer to take advantage of the new openings? Are the trees selected to be removed void of wildlife dens?

    Another option could be to kill some trees and leave them stand for habitat trees.

    I have seen timber value get in the way of ecological value many times in management decisions. I say this not to be critical and know firsthand that economics do play a large part in a manager’s decision.

  5. Hi David, If I were to remove any native tree then my deciding factor would be based on both current vegetation and predictions of vegetation structure based on expected fire intensity for the localized area. The point is to maximize diversity of habitats, but not try to force a habitat into something that is not suitable for the site. Are species currently under the oaks unable to reproduce? Then maybe thinning of white or burr oaks is justified. Is the understory under the oaks void of any quality species and adjacent to open areas with rare species? If so, then maybe cutting burr or white oaks to expand the open area is justified.

    In contrast, I would not cut maples or basswoods in an area with quality mesic forest species that is in a location sheltered from fire. Examples of fire sheltered locations include the eastern side of water courses and the bottoms of steep northeastern facing slopes.

    In a location on the eastern side of a stream a land manager was removing invasive species from a disturbed area. He was cutting all the box elder trees along with all the non-native invasives. I asked him to leave the old box elder trees. He initially did not want to leave the box elder trees because they are "weedy." I explained that the disturbance means the site does not have much short term potential and the box elder trees will produce competition that will help keep the non-native invasives in check. Leaving the box elder trees created a light dynamic similar to a savannah. Over time the sapling oak trees that were planted in between the box elders should over take the site. The less competitive box elders should disappear by attrition as they yield to the more stately oaks. In the mean time, less work had to be done to clear the site and less work will need to be done in the future to control non-native invasive species. Everything has trade offs.


  6. Thanks for the chance to contribute to the conversation, which is very timely. At the moment, I'm wrestling with decisions about tree removal at both a nature center and a forest preserve.

    Our nature center site was managed for many years as a savanna, while in fact it is a wet mesic woodland or flatwoods. We have the enviable problem of being overstocked with oaks, mostly swamp whites and pins, of all sizes, from seedlings to giants. We also have a few bur, white and red oaks, with hackberries, basswoods, elms, silver maples, willows, small cherries and numerous dying ash trees. We are severely constrained in our ability to burn, so tree removals are a necessity if we want to have understory, shrub or herbaceous layers.

    Many people still believe that cutting any tree is evil. At any site, even the "easy" decisions may be difficult for stewards to carry out, based on the "do no harm" dictum and the strong emotions we all carry with us about trees. It took me two years to make and carry out the simplest decisions about tree removals. After nearly five years, I am finally confident enough in my observations, experience and lumber-jacking skills to carry out medium to difficult decisions.

    To the medium criteria, I would offer
    - cut trees of all kinds and sizes. A generational mix is optimal.
    - to reopen an overgrown savanna, it may be necessary to remove almost all fire-prone and aggressive species, such as maples, red cedars, basswoods, ashes, etc. to in order to allow enough sunlight to grow grasses for fuel and re-establish a burn regimen.

    To the hard criteria, I suggest the following ideas
    - eliminate all non-native trees and landscape cultivars
    - clarify that cutting black cherry (Prunus serotina) is separate from decisions about shrub-like cherries, such as wild plum and chokecherry
    - encourage healthy understory and native shrub layers, which have largely been lost in our region. Maybe even a thicket or two of gray dogwood!
    - small size of most sites is a confounding condition. There is not enough space for any one species or type of vegetation or ecosystem, much less everything that should be restored or conserved!

    Jeff Weiss

    1. I'm intrigued by your comment about people who suggest cutting any tree is evil. Our food comes from plants and animals that were cut or harvested. Soil itself is a constant flux of consumers and recyclers. Your objectives as manager sounds well based and thought out - if there's no understory to burn then it's tough to expect balance and diversity. There will always be some naysayers, some will even object to cutting invasives. Can you tell me what kind of wild plums do you have and where your site is?

      To follow up on Paul's note. If we are going to be true conservationists and environmentalists, I believe we have to start thinking about our local woodlands as potential sources for resources such as firewood and building material. Why do we import so much wood to our area from other regions or countries when we have a surplus of it here already. Perhaps not enough to meet the demand for everyone in the region, but enough to offset our imports to some degree. I don't see why we shouldn't be finding ways to remove the weedy mesophtic trees today as firewood (buckthorn is great firewood!), woodchips, particle board, paper or even lumber for the larger ones, while we do this initial clearing work. Then as time goes by could we not do light thinnings of oak trees every 20-30 years to maintain an open woodland environment in a world where our fires are few and far between?

      I realize there are political and economic issues to deal with here, but it seems like the most environmentally sound thing to do, and it could also reduce the cost of restoration work. Firewood and fine lumber seem like the low hanging fruit since this can be done profitably in a relatively small scale without a lot of infrastructure.

      Frank Hassler
      Good Oak Ecological Services

  7. We actually witness such a brief moment of time, while our restoration work needs to be seen across decades, even centuries. It will help us to learn to see trajectories, ramifications, implications of our actions over longer spans of time. For example, whether and how young trees we leave will come to occupy the canopy as older cohorts meet their eventual demise.

    Now, what about shagbark hickories in mixed oak woodland and/or savanna? I work a site where the hickories are wildly successful. We have lots of hickories in seedling, sapling, and young-tree stages of growth. They need to be thinned. While our first priority is to remove all the nonnative species, we will have to come back and remove pole hickories. Which ones to remove, and which to spare? Under what circumstances do we leave them to sort it out amongst themselves? Inevitably we play the role of gardener in these natural areas: even though we endeavor to maintain our scientific objectivity, it is not always possible (nor perhaps is it necessarily desirable) to proceed with complete detachment. It is, after all, our deep caring that brings us to this work in the first place.

    1. Greg, I completely agree that we need to view restoration in larger blocks of time. A woodland newly cleared of buckthorn is simply not going to become high quality within 2, 5, or 10 growing seasons. The challenge is to keep the trajectory moving upward.

      You are entirely right about hickories. Both shagbark and bitternut are successful in our white/bur oak woodland, even more so than the red oaks. The reds have been impacted by severe storms within the last 7 years that have taken down the weaker mature trees. This has created canopy openings that should prove beneficial in the long run.

      Because the hickories succeed, decisions about cutting them should not cause agony. Pole hickories on our site crowd each other and other trees. I think a good strategy would focus on sparing the larger open grown examples and thinning the young ones that are crowding. The trees are reproducing freely so cut away. This is a decision we should make on our own site, where we all too often follow the temptation to open new areas and lose sight of long term strategy in recovering ones.

      I am wrestling with the idea that a managed site with a controlled fire regime is perforce going to result in a different type of woodland than was present in pre-settlement days. Steve asks if the woodland in the last photo is healthy enough. Clearly it is a vast improvement on what was there previously. The biodiversity is impressive. Cutting pole trees at this point seems like a sound strategy with little potential downside.


  8. Much of my tree thinning targets the edge where an oak woodland opens into a field. Black oaks fill in this border much more aggressively than other oak species. I remove about half of the black oaks. More can be removed later if necessary. I don’t focus on the outer trees, since they are generally more open-grown and healthy. I create a savanna strip that boosts light levels and allows more wind to penetrate the interior. This should increase the intensity of the landscape fires so that over the longer-term, a healthier understory can develop along with a less crowded, new generation of oaks.

    I pay special attention to sources of light—any areas where trees do not grow densely whether because of the presence of a pond or wetland, a prairie or field, or even a road. A light source to the south gives you the biggest bang for your buck, so I tend to focus on the woods north of an open area.

    In upland oak woodlands being swamped by young maples, basswood and black cherry, I’ll aggressively remove the invaders. If an area is burned enough, such projects become less of a priority. Removing trees that are native to a given habitat, but which are present in too great a density to be healthy can be tricky. But since a lot of individuals will remain, I don’t fret too much about removing some. If young red and black oaks grow around a young white oak or bur, I’ll remove the reds and blacks since these oaks seem to be increasing, while the white and bur are decreasing. Many of my decisions are practical. If two hickories are ten feet apart, I’ll remove one. If a smaller tree grows next to a larger tree of the same species, I’ll remove the smaller one. If a tree has a pronounced lean so that it can be dropped safely and cleanly, I’ll remove it, rather than deal with a tree that will get hung up as it falls.

    I generally focus such work on an area with a rich understory or a rare plant. The vegetation present will communicate what light level is appropriate by how robustly it blooms and the quality of seeds it produces and the seedlings that are able to establish themselves.

    The original surveyors of northeast Illinois in 1840 supposedly often mentioned the presence of hazelnut in the woods, but although it is present in one high quality woodland that I manage, it never produces a nut there, so seemingly the light levels are still too low for the hazel. And this woodland’s mature white oaks have been decimated by a beaver from a nearby pond.

    One aspect of the original survey records that is particularly striking is that the trees the surveyors marked in upland areas were not particularly large. The big, old oaks are interesting historical relics whose shade-shorn lower branches readily relate how the woods have closed in, but the most beautiful tree from an ecological perspective is an open-grown oak with a dbh of about 12”.

    Joe Neumann

    'If we are looking for oak regeneration in woodlands, perhaps we just have to wait until some of the older oaks die to create a gap where sunlight can get in? If we have good reason to think that speeding up the process will help the ecosystem overall, we can create some gaps ourselves. I usually focus on very aggressive clearing of weedy mesophytic trees in patches to create these gaps. I have never had the guts to cut or girdle a mature oak to create a gap, but we'll often thin-out mid-sized hill's oak and hickory to open a gap.

  10. A few thoughts..

    Overgrown savanna: In addition to questions regarding which species to cut and how many, an important aspect of a savanna is that of the distribution of trees. Trees in a remnant savanna are not uniformly distributed, rather they are "clumpy", which lends itself to a diversity of plant communities within the larger savanna context due to varying light, moisture, and other factors. One of the things that Middlefork taught me was that a big reason for the high level of plant diversity of a remnant savanna when compared with remnant prairies and woodlands is that a savanna has not only savanna species (species that are more commonly encountered under moderate light conditions), but it also has prairie and woodland species - all in one place. This makes the playing God that you refer to even more challenging, for we must also consider the spatial aspect when deciding what trees to cut down. I am not aware of any formula for this - so it is an intuitive decision process that should be based on observation of the best available savannas that are left. Of course, if one has decided to cut down all trees of a given species, then this problem goes away.

    I agree with your reference to size on this issue - the larger the site, the more one can afford to leave a few trees other than bur, white, scarlet oak and hickory, to enhance diversity. I don't mind leaving some other species as long as they do not drive the overall conditions of the community. Nature is not perfect; I see some restorations that look "squeeky clean". But it is also true that most of the suspect species in our oak woodland restorations - basswood, ironwood, sugar maple, elm, ash - are quite abundant elsewhere in our preserve. So removing some of these from an oak woodland will not remove them from the site overall (or even significantly reduce their abundance, frankly). On red oaks, yes other oaks will not grow in their shade but succession is a natural process and they have their niche within that process. Don’t get me wrong, we have had way too MUCH succession, that is what this conversation is about, all I am saying that a diverse landscape should accommodate some areas where succession is allowed to happen. (I know, you’re thinking “Well THAT shouldn’t be a problem!” And you are right.) Interestingly, Middlefork has a problem with too many pole shagbarks, which of course is less of a problem that red oaks but still, it poses a similar challenge for the land managers.

    Another point is that for simplicity we are more or less discussing “oak woodlands” as though they are all the same. But in fact, we have dry-mesic, mesic, wet-mesic etc. and our characterization of which natural community an oak system fits in may determine which trees to cut, or at least how many. You kind of allude to this with your example of leaving some elms in wet spots. Admittedly, sometimes out on the landscape it is hard to be precise, especially with a landscape such as Deer Grove which has quite variable terrain. But on a larger scale, this should be given some consideration.

    Your oak woodland discussion states the dilemma perfectly. I agree with the notion that we do need to make tough decisions to remove things that would likely have been much less abundant under presettlement conditions. Stated differently, to NOT face up to and make these kinds of decisions (admittedly, in the face of incomplete information) is in fact making a decision. We all know our oak woods are way overgrown, and yet we proceed so cautiously. We have been much too timid in our approach (speaking for our work at DG). Being cautious and taking an experimental approach is good to a point. “First, do no harm.” But at some point we have to look at the evidence that we see and apply our intuition to what the available data and our observation and realize that we are losing species, we are losing communities.

    Thanks for the opportunity to comment!

    1. I think the "formula" for the number and species of trees that need to be cut is really based on exposure to drying southwestern winds and soil moisture holding capacity. The less moisture the soil holds, (thin or stony?), and the more exposed to drying southwestern winds then the more drought and fire adapted the ecosystem. Removal of native invading trees should be concentrated in areas where the soil and wind paths would have excluded them if fire had not been eliminated from the landscape. A given species will occupy a range within the continuum. Instead of cutting 1/2 of a given tree species, maybe it would be best if people cut in a range from almost all the trees of a given species in locations where fire intensity and frequency would be predicted to eliminate them down to none of a given species in locations expected to be sheltered from fire.



    2. One way to create a "formula" to look at would be age classes among the trees on the site. Basically you do a survey of the trees and divide them up by size class, 0-4", 4-8", 8-12" on up (but use cm of course of the scientist will get all huffy). Then plot it out on a bar graph. What you will often find is that you can quantify something in a meaninful way, something that is often (but not always) blatently obvious to the trained eye: there are a few big old oaks, a lot of young trees of other species, and almost no young oaks. This fact alone is often something that the general public can understand is concerning... if we don't change the management of the site, we won't have any big oak trees anymore. If we can then tie this data to a message about how woodland management has been poor in the past and how it can improve in the future, we have a narrative that people can relate to: people screwing up nature, and now we have to try to find a way to fix it.

      It would be really nice though if someone could develop a program where you could enter the soil type, aspect and other features and get a range of what tree species "should" be in a spot and how dense they should be. It would be a big range, but it might be a useful starting point.

  11. OK, it looks like I am able to post now, but only after setting my browser security to the lowest possible level (allowing all cookies and tracking by websites). I will probably have to slowly ratchet it back up until I break posting again. Others with this same problem will have to also play with their security preferences.

    Anyway, I agrees with those that said my use of the term mesophytic can be misleading. Sorry, its just the kind of thing that rolls of your tongue after you get a masters degree in forestry. :) Perhaps we need to define a better term, but I think it should express how opportunistic these trees can be in the absence of fire. Perhaps "aggressive, fire-intolerant trees"? Fire-phobic? Shade-o-philes? I think we need some term, or phrase to explain why these trees don't belong in the "forest".

    On major problem is our changing view of ecology as we learn more about how it works. Here in Wisconsin Curtis's Vegetation of Wisconsin is considered "the bible". Sure, it is a great resource for understanding conditions on the ground in the 1960, and how they have changed before and after that time period, and it does a good job of identifying and classifying many natural community types around the state. However, at that time the lack of understanding of fire as a regulatory agent in ecosystems, caused Curtis and his crew to seriously misinterpret the "southern oak forest" community types. Such as, identifying many degraded oak woodlands as "southern dry-mesic forests". The Curtis community definitions are still used today by the DNR, and need some serious updating:

    I think we should also be careful how we apply the term succession. Many people, especially those with only a superficial understanding of how nature works, are familiar with the idea of succession. What we are talking about here is secondary succession. And while succession is a good model to understand how change occurs in an ecosystem, it is a bit outdated with a better understanding today as to how critical "disturbance" is as a regulating agent in ecosystem to maintain stability and function. These aggressive, shade-producing, fire-intolerant trees are indeed succeeding the oaks in our woodland but this is not "natural" succession... some new verbiage is clearly necessary here to keep us from falling into verbal traps, and to make the need for tree clearing and other restoration work clear to the general public.

    1. This is Frank aka Good Oak. One other thing I had to do to get the comment to post was to hit the "Preview" button first, and then fill in the Captcha before it would allow me to post!

  12. I am generally following similar practices although I have few places with enough oaks to worry about thinning them and leave them for later decisions. What I am curious about is whether others are setting goals in terms of the amount of sunlight reaching the ground. The Chicago Wilderness Biodiversity Plan identified 50% to 80% canopy cover as appropriate for woodlands and 10% to 50% for savannas. I am being guided by this although I don't have an exact method to measure it. In woodlands I'm looking for 10 to 50% direct sunlight at midday in woodlands over fairly large areas.

    Another question is how to judge thinning in savannas. Again % shade seems valid. Perhaps the presence of strong lateral branching on young members of the white oak sub-family could be another. The dying of ash species seems to be a good opportunity to reach canopy cover targets.

  13. Here is another problem that should be given consideration. Failure occurs at the weakest link. When damaging winds occur, will your woodland be more resilient with some shade tolerant species? If you remove all the shade tolerant species then the burr oak and white oak are now the weakest link. Strong winds will snap them off one by one over time. This could be desirable. This might be just what they need to reproduce.