The response of the forest to drought

This post provides some on the ground research and consistent but separate modeling results that demonstrate the importance of stand density in coping with climate change and therefore the importance of sustainable forest management. Hopefully this will change some minds on the importance of strategically managing density.

A) The response of the forest to drought: the role of stand density and species diversity This article is an attempt to quantify previously established science.

1) “Droughts affect wood formation through the reduction in photosynthetic rates due to stomatal closure, reducing the amount of carbohydrates available for building new cells.”

2) “used tree-ring data from long-term forest plots of two pine species, ponderosa pine (Pinus ponderosa) and red pine (Pinus resinosa). The experiments were distributed in different geographical areas in the USA and they covered a large aridity gradient. They quantified growth responses at the population level to express both resistance and resilience to drought in relation to the relative tree population density, finding out that reducing densities would enhance both growth responses to drought. Trees growing in denser populations were more negatively impacted by drought and this has been shown in all three biogeographical areas.”
NOTE from “Climate Change Research Focuses on Great Lakes Forests”: “ASCC is monitoring the growth, health and survival rates of the trees in these forests, and focusing on three key qualities: resistance, resilience and transition. Resistance measures a species’ ability to remain stable and productive in a drought situation, resilience is a tree’s ability to return to normal productivity after experiencing an environmental change and transition refers to circumstances that encourage ecosystems to adapt to changing conditions.”

3) “This study confirms once more that the vulnerability of monospecific coniferous forests to increasing drought can be reduced through thinning interventions, which represent a viable adaptation strategy under climate change.”

4) “investigated the drought response of 16 individual tree species in different regions of Europe and evaluated if this was related to species diversity and stand density. Based on previous findings indicating that combining species with complementary characteristics is more important than simply increasing species diversity to cope with drought, their results indicate that species growing in a mixture are not always less water stressed than those growing in monoculture.”
See also: a) “Species composition determines resistance to drought in dry forests of the Great Lakes – St. Lawrence forest region of central Ontario” b) “SPECIES RICHNESS AND STAND STABILITY IN CONIFER FORESTS OF THE SIERRA NEVADA” c) “Functional diversity enhances silver fir growth resilience to an extreme drought”

5) “Investigating these effects at the level of species identity (i.e., different combinations of species) is more advisable than doing it at the level of species richness (i.e., abundance of species), because different mixtures respond differently depending on the region. If we consider that different provenances of the same species can show different adaptation strategies to cope with drought, the situation may be even more complex.”

B) Ecosystem services, mountain forests and climate change
Note: This modeling effort passes the #1 smell test in that it agrees with already established scientific principles while adding quantitative measures that support the previously known trend but shouldn’t be taken as absolutes.

1) “it is estimated that about half of the global human population depends – directly or indirectly – on services delivered by mountain forests. It is therefore essential to assess whether multiple ecosystem services can be provided to human societies in the future. Given that climate is changing fast, the consideration of climate change in scientific assessments is a must! Let’s not forget that European forests are managed since centuries (check out this nice book about the history of European forests). Thus, changes in management regimes must be considered as well.”

2) “in the Iberian Mountains their simulation results indicate that forest management, rather than climate change, is responsible for a reduction in carbon storage and biodiversity. On the contrary, in Western Alps changes in climatic regimes could induces large alterations in the supply of several ecosystem services, particularly under the most pessimistic future climate scenarios. In other areas (e.g., in the Slovenian Dinaric Mountains) climate change would strongly affect ecosystem services, albeit differently depending on elevation and stand conditions.”

3) “This confirms that management is a strong driver of forest dynamics in European mountains, and it can highly modify the future provision of ecosystem services (i.e., more than the direct effects of climate change!).”

16 thoughts on “The response of the forest to drought”

  1. I’m looking forward to an urgently needed, definitive, and rigorous agronomic research program aimed at determining whether thinning lettuce early in the crop’s life allows the individual plants to better withstand adverse environmental factors (e.g. reduced irrigation frequency), reduces mortality and yields a more abundant crop. This would involve numerous replications on a range of soils and climatic conditions. Subsequent programs might focus on carrots and beets.

    • Mac

      You bring back very pleasant memories from the 50’s. Digging/turning the soil, planting, thinning and weeding my “Mother’s” garden under her very close but loving supervision.

      Sounds, to me, that you are looking for a way to get out of some work. 🙂 Enjoy the fruit of your labor! 🙂

    • Hi Mac, How many wolves, or elk, or bull trout, or wolverines or other native wildlife species live in that lettuce patch? How many creeks and springs and rivers are found in the lettuce patch? How much clean water or clean air does the lettuce patch produce? Do people recreate in the lettuce patch? And, yes, what about carrots and beets? How do all these questions apply to those vegetables?

      • Matthew

        You miss the whole point. As explained many times before on this site, plant physiology rules. Forests create a large number of the many ecosystems / habitats that all of your concerns depend on for their existence. In the short term you can bend the resultant findings of long established and repeatedly validated statistically designed studies and millions of acres of operational trials that confirm the universal principles/laws/rules of plant physiology. But you can only bend the rules so much and only for so long, then you have to take the responsibility for destroying the very habitat/ecosystem that you claim is so important to you and upon which the items about which you are concerned depend.

        You can’t have everything you want. You need to understand the need for trade offs between conflicting objectives and conflicts between the needs of different forest dependent species. You need to understand that you can’t decide what kind of a forest you want by only looking at one of the forest dependent species. You need to understand the priorities to make those trade offs. You need to understand the interplay between each component of the ecosystem to understand the priorities. Without sustainability of the ecosystems that these things depend on you have nothing. Without a balanced reasonable degree of continuity of all stages (habitat niches) of an ecosystem you will have wild swings in population of forest dependent species which raises the risk of extinction because of the increased odds of an exogenous variable like extreme weather hitting at the same time as an unnecessarily low population exists.

        Mammals for the most part are more mobile than a forest. Many mammals are designed to move around to reduce their risk of mortality due to insects, disease, lack of diversity of habitat, and as prey. Trees and the ecosystems that they depend on, not so much. As you will see in my next post, elk are very dependent on early seral habitat. Unfortunately the focus on old growth, dense stands and hands off management has created a dearth of early seral elk habitat. A more even distribution of age classes will provide more sustainability and at a higher level than the currently mismanaged federal forests.

        Since you are a big elk hunter let’s look at the interplay between elk and the ecosystems that they depend on. To do this I will begin a new post on the impact of forest management or lack thereof on elk.

    • Reference to agricultural models really affirms my assumptions about people who think they understand natural forests.

      The goal of growing lettuce is to feed people. Meeting this goal requires minimizing mortality in their field and maximizing yield for off-site uses.

      The an important goal of growing forests is to provide habitat for viable populations of wildlife, including scores of species that thrive on dead and dying trees. The goals is NOT to minimize mortality but rather to manage the forest so that trees can fulfill their entire lifecycle both alive and dead.

      Here’s a great place to start to understand the incredibly diverse functions provided by dead wood in forests. Rose, C.L., Marcot, B.G., Mellen, T.K., Ohmann, J.L., Waddell, K.L., Lindely, D.L., and B. Schrieber. 2001. Decaying Wood in Pacific Northwest Forests: Concepts and Tools for Habitat Management, Chapter 24 in Wildlife-Habitat Relationships in Oregon and Washington (Johnson, D. H. and T. A. O’Neil. OSU Press. 2001)

      The old view:

      “Snags, the grim skeletons of once flourishing forest giants, are the outlaws of the logged over lands of the Northwest. They stand, fringing the skyline like the teeth of a broken comb, in mute defiance of wind and decay, the dregs of the former forest, useless to civilization and a menace to life of man and forest. … Snags deserve outlawry, yet they continue to practice murder and incendiarism on millions of acres of fertile Douglas fir lands. … Some operators refuse to compromise with them at all and say “thumbs down” to every snag over 12 feet high. Uncle Sam on National Forest timber sales demands falling all over 15 feet high and 12 inches in diameter …. The day will come when snags are banished altogether from Douglas fir logged-off land. They will be considered a public nuisance and all felled everywhere in logging as a matter of course. It has even been suggested that they be legislated out of existence by making it obligatory to fall all dead trees ….

      Munger & Drake. 1926. Snags. The Timberman. Portland, Oregon. December 1926. The legacy of this mindset is still being felt in the forests of the Pacific northwest. After 1926, foresters just became more efficient at removing snags.

      Consistent with the new view, the Forest Service has a public education program called “Animal Inn” intended to inform the public of the value of dead wood:

      Nearly a third of all forest creatures depend on standing dead or fallen trees for their survival. ANIMAL INNS provide shelter, nest sites, and feeding areas for over 1200 species of birds, mammals, amphibians, and reptiles; over 60% of which feed on insects. These insect-eating species act as natural biological regulators to dampen the effects of insect outbreaks in forested lands, thereby performing an important ecosystem function. Fish benefit from trees that have fallen into stream channels.

      What’s so important about snags and down logs?
      Snags provide homes to owls, woodpeckers, bats, squirrels, bluebirds, wood ducks, swallows, mergansers, weasels, raccoons and many other animals. More than 50 species of birds and mammals use snags for nesting, feeding and shelter. A lack of snag cavities for nesting can limit populations of some bird species. Snags larger than 20 inches DBH are in short supply on private lands. Snags can be created from live trees, and wildlife respond quickly to their availability.
      You can reduce the cost of leaving snags by selecting rotting or deformed trees. In eastern Oregon, down logs are used by 150 species of wildlife, including amphibians, reptiles, birds and mammals. Logs are also important to certain insects, fungi and plants. … [A] forest without down logs may have fewer species of plants and animals.

      Oregon Forest Resources Institute 2011. Oregon’ Forest Protection Laws – An Illustrated Manual, Revised Second Edition.

      • 2ndOutLaw

        1) As I pointed out to Matthew above, like it or not the laws of plant physiology apply to trees just as surely as to garden plants. Ignore those laws and your efforts will be wasted. Your problem is that you are tying to treat a single system without considering all of the relevant factors and inter-dependencies.

        2) I don’t know why you got off on dead wood. I certainly don’t disagree with diversity or the importance of dead wood so I don’t know what triggered you to divert the discussion. Mac and I are both well educated and experienced foresters. You are not telling us anything that we don’t know. Your “new view” may be new to the forest service in your humble opinion but it is certainly not new to us and probably not to the USFS who is now touting a new program based on old knowledge.

        3) You rant like there is some dictate in forest management that disallows the retention/creation of dead wood. To the contrary, especially considering the objectives for the federal forests, forest prescriptions can be tailored to meet multiple objectives including retention/creation of dead wood and doing so while complying with the laws of plant physiology. Under forest management, species like the black backed woodpecker could have a more uniform distribution (over time and location) of fresh dead wood from hot spots within controlled burns and snag retention/creation during thinnings, regeneration harvests and salvage operations as opposed to reaching dangerously low populations while waiting for the next large catastrophic fires to destroy soils and the desired forest cover in large, undispersed acreages for decades when the BBW can only use those snags for 6 years and then the population is going to crash again. Consider also that a low population can not expand fast enough to use most of the snags during the 6 years that the snags created by a catastrophic fire are suitable habitat.

        Read more at this new post

        • Hi Gil. 2ndLaw has been an active and valuable participant on this blog for many years. Whoever 2ndLaw is they have provided a lot of good information, insights and scientific studies and citations…and they have done so without any of the vitriol we see in many other comments on this blog. As such, please refrain from referring to 2ndLaw as “2ndOutLaw.” Thanks.

          • Matthew

            Re your: “Whoever 2ndLaw is they have provided a lot of good information, insights and scientific studies and citations…”
            –> You need to replace “good” with “false” and “scientific” with “un-scientific”.

            Re your: “please refrain from referring to 2ndLaw as “2ndOutLaw.” Thanks.”
            –> No thanks – whatever person, persons or organization 2ndOutLaw is – They hide behind a mask disseminating untruth. That makes them an “Out Law”
            –> At least you don’t hide who you are, otherwise you’d be the 1stOutLaw.

            • Howdy Gil,

              Can you please provide examples of where 2ndLaw has supposedly provided a lot of false information and un-scientific studies? Seems to me, as someone who has read and observed 2ndLaw’s comments here for a few years now, that 2nd Law provides more scientific citations than just about anyone. Is that the false info and un-scientific studies you speak of?

              You also are away Gil, that Larry Harrell used to mask his real identity on this site? And that Sharon has made a point of accepting comments made by people on this blog who would like to remain anonymous? Perhaps we should all abide by that rule.

              • Matthew

                Are you trying to be deliberately dense? You know that I have already pointed out out every example of false, un-scientific and otherwise misleading statement that I have come across – you are truly the king of obfuscation. You look it up. It won’t take you long. But then you already know it. Your attempts to deflect and cast aspersions are pretty transparent. Your attempts to intimidate are a joke.

                Again, you resort to misdirection. I accept “it’s” right to post anonymously and you know it. So why are you trying to deny my right to give “it” a sarcastic nom de plume? It doesn’t harm anyone when no one is identified.

  2. Maybe this is semantic, but I don’t think that “ecosystems adapt” .. under different environmental conditions, species of plants change, and animals, arthropods, microbes and so on, each in its own way. In that sense, the “ecosystem is changing” but ecosystems always

    Also, almost any change would help some ecosystem services and not help others.. I don’t think being nonspecific helps anyone’s understanding.. which I think is Matthew’s point only- from a different angle. One things get so abstract, it’s possible to say anything about anything and in some respects it’s true.

    • Sharon

      Re: “I don’t think that “ecosystems adapt””
      –> It is semantics. Think of it as “succession” where a stand of a specific ecosystem type (i.e. a specific broad forest ecosystem like doug fir) evolves/moves from one state into another (i.e. doug fir to mixed conifer or over a longer period from pioneer (shade intolerant species) to climax (shade tolerant species). Or, think of it in terms of a succession of stages within said broad ecosystem classification (i.e. doug fir) from one stand stage (i.e. age group providing a distinctly different ecosystem/habitat niche) of succession to another such as from an early seral habitat niche to mid stage habitat niche while remaining a pure doug fir stand (hence the term “transition” = change from one thing into another). “Transition” is the term used in the Woodstock modeling system (internationally used and around since the late 80’s or early 90’s) which prepares a matrix of possible alternative paths (transitions) for each stand for submission to a Linear Programming engine for optimization of an objective function (which could be a biological, financial or other metric) within the matrix of paths and their impact on the objective function while complying with the imposed constraints.

      Next, I will address Matthew’s point (see above) which has been addressed many times previously removing the ambiguity and explaining the trade offs that you are concerned about.

      • “Succession”, in today’s world, seems mostly marginalized and obsolete. Since we cannot regulate, or properly mitigate human issues and impacts, that makes “natural succession” a very moot point, in many areas, IMHO.

        • Larry

          Yes, and our federal forests and the species that depend on them are paying for it and will continue to do so unless we prioritize and apply validated science to the best of our limited ability.


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