Clearing the Mist

Clearing the Mist is real-time commentary by Delphi Advisors on developments, clues, patterns, and events we believe could affect the U.S. economy, and particularly the Forest Products sector...

...or sometimes it's just a way to let off some steam.


Thursday, October 30, 2014

Zombie Trees

Halloween seems an appropriate time to highlight a national horror story.  Although this post looks at it through the prism of Idaho, sadly the tale is unfolding in many places throughout the U.S. West.


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We start the tale innocently enough: comparing the number of standing trees per acre on forest land across Idaho.  But first, a bit of background.  In USFS nomenclature “forest land” is the broadest classification of land with trees growing on it, including lands that have at least 10 percent forest cover; timberland refers to forest land that surpasses a productivity threshold and is not legislatively reserved from being actively managed. 

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According to the USFS's Forest Inventory and Analysis ("FIA") unit, there are nearly 21.5 million acres of forest land across the state.  Eighty percent of the forest land in the state is managed by the federal government, with the vast majority (76 percent of the state’s forest land) managed by the United States Forest Service (“USFS” or “NFS”).  The State of Idaho manages six percent of the forest land in Idaho with the remaining 14 percent managed by private land owners.  These lands are interspersed with one another across the state.

With that is background, let’s plunge ahead with our tale.  For the three primary forest managers/owners in Idaho, the USFS, the State of Idaho (“IDL”, for Idaho Department of Lands), and private land owners, the average forest land acre carries roughly the same number of live trees (122 per acre for USFS, 119 per acre for IDL, and 108 per acre for private).  However, the number of standing dead trees per acre on the USFS (43) is roughly double the number of standing dead trees per acre on State (20) and Private lands (14).  Why would this be?  Remember, the USFS doesn’t represent an isolated pocket of property but rather is by far the most significant land manager in terms of geography within the state.

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IDL and private land is generally more actively managed, including higher harvest activity, than forest land managed by the USFS.  For instance, as can be seen in the graph below, although USFS managed lands represent 76 percent of all forest land, it currently accounts for less than 15 percent of the annual timber harvest in the state.   On the other hand, the state, comprising six percent of the forest land acreage, accounts for nearly 30 percent of the harvest.  In the case of private land owners, 60 percent of the annual harvest is sourced from their acreage, representing 14 percent of the forest land in the state.

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To further examine the link between active management and tree mortality, the next chart focuses on USFS land only.  As can be seen there are 10 columns in all, comprising five sets of two columns each.  Each set of two columns shows the number of living trees and the number of standing dead trees per acre.

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The far right set of two columns on the chart above corresponds to the USFS graph shown in the prior trees per acre by ownership chart.  The other four sets of two columns segregate USFS forest land into four different categories.  The first two sets look at more productive forest land  while the second two sets of columns look at less productive forest lands.  The more productive forest land area is further sub-divided between acres that are not reserved, i.e. that are open to active management, and acres that are reserved, or legislatively withdrawn from any active management occurring on them.  Designated wilderness areas are an example, the most common in fact, of acreage that is reserved from active management.  Similarly, the less productive acres are sub-divided between not reserved and reserved.

Several patterns emerge when the data is analyzed in this way.  First, the more productive lands carry more lives trees per acre than less productive lands.  Second, the ratio of the number of dead trees per acre compared to the number of live trees per acres is higher on less productive lands.  But, third, and most important here, is regardless of productivity, there are more dead trees per acre on lands where no active management is possible.  Fourth, on the most productive areas that are open to be actively managed, the number of standing dead trees per acre is still nearly double that seen on IDL and private ownership.  Thus, on the USFS even acres where ostensibly active management can be practiced, not enough is being done and trees are dying.

Beyond, the charts and numbers, the reality is all too obvious to anyone who looks at Idaho’s national forests.  Suppression of fire and significant reduction harvesting, both for regeneration and thinning, have allowed forest managed by the USFS to become overcrowded and old.  In the relatively dry climates of the Inland West, the old, overcrowded conditions weaken trees, making them more susceptible to insects, disease, and death.

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Trees per acre are one thing and seem bad enough but when the number of dead trees per acre are multiplied across the size of the USFS holdings in the state the magnitude of the losses becomes even more sobering.  The next chart compares the volume represented in standing dead trees on the USFS compared to volume in live trees on other ownerships in Idaho.  As can be seen, the volume represented in the standing dead trees on USFS timberland (not reserved and productive lands) exceeds the live volume on any other single ownership class in the state.  Total standing dead volume on all USFS forest land is nearly equal to the total live volume on all other ownerships combined in the state.

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For those concerned about global climate change and green house gases, there is an additional element of this carnage that is often overlooked.  As is well known, trees grow by utilizing atmospheric elements, including carbon dioxide, other nutrients from the soil, sunlight energy, and water.  One result of this growth process is a reduction in carbon dioxide, fixing carbon within the tree's cellular structure and producing oxygen as a by-product  When a tree dies and begins a slow process of decay, the fixed carbon within the tree is released.  However, this process will take a long time in the dry Inland West so a significant amount of carbon remains ‘stored’ in the dead trunk for an extended period of time.  However, no new tree can take its place while it stands, and so that portion of the forest is no longer in effect exchanging carbon dioxide for oxygen as it once did while carbon that had been stored within the tree during decades of growth slowly leaks away.

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But standing dead trees and standing dead volume speaks to what has been --- not what is happening.  The chart below begins to look at what is happening now, not what has been.  It compares the volume in trees that die annually to the volume of trees harvested annually by ownership.
 
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The first two stacked columns on the chart compare mortality on non-reserved forest land acres – acres that are open to active management – to 2012’s harvest.  Each column is sub-divided by ownership to depict the contribution of each ownership category to the state total.  The comparison is made on non-reserved acres because those are the only acres on which active management, including timber harvest, can occur.  The last column on the chart depicts the annual mortality occurring on forest land acreage reserved from active management.
 
Total mortality, on both non-reserved and reserved forest land, is nearly 4 times the amount of volume being harvested annually state-wide.  The annual mortality on the USFS acres that are open to active management is over 18 times the volume of the annual harvest from those same acres.  Finally, the annual mortality on the 3.8 million acres of reserved – Wilderness – acres in the state exceeds the annual harvest on the 16.4 million acres of forest land in the state open to active management across all ownerships.  In a word, the Idaho Wilderness is being slaughtered.

The chart below shows net annual growth and annual harvest on Idaho forest lands.  The ratio of net annual growth to annual harvest ("growth/drain ratio") is a common, sometimes overused, metric used to test harvest intensity.  Net annual growth is the amount of growth occurring in a year minus the amount of annual mortality.    As can be readily seen, not only does state-wide net annual growth exceed state-wide harvest, the net annual growth on each ownership exceeds the annual harvest for each individual ownership class in the state.  Notably, the "growth/drain" on private ownerships (1.33) exceeds the same ratios on USFS (1.17) and IDL (1.12).

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Looking at those results on the USFS one might be tempted to conclude harvest levels could be increased only slightly before harvest exceeds net annual growth, prompting forest inventory to fall.  However, this is one example where the growth-drain ratio alone doesn't provide an adequate picture of forest conditions; in this case, the high level of mortality distorting what is occurring on USFS lands.
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The chart above separates the components of net annual growth apart and further separates them by non-reserved (i.e. open to active management) and reserved forest lands for each ownership class.  As can be seen on this chart, on most ownerships annual mortality is a fairly small relative to annual growth (16 percent on IDL and private forest land in Idaho).  Unfortunately, this is not the case for the USFS.  On USFS non-reserved forest lands annual mortality is a whopping 76 percent of annual growth.  However, on reserved forest land the picture is even more dire; annual mortality is 206 percent of annual growth.  Idaho’s spectacular wilderness and back-country areas are slowly dying.  Dying by starvation, dying by thirst, dying by strangulation.  Combining the non-reserved and reserved acreage results in a slightly positive net annual growth where annual growth exceeds annual mortality by four percent.

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The next chart (see above) now completes the picture, pitting harvest against net annual growth on the acres open to active management.  On USFS it’s clear the net annual growth on acres open to active management exceeds harvest by over 500 percent.  This is a radically different picture than when comparing the annual USFS harvest to the USFS property total where net annual growth is much lower due to the annual mortality occurring in Idaho’s wilderness areas.  However, the extremely positive net annual growth to harvest on USFS lands needs to be understood in the context of other clear trends on USFS lands: rampaging mortality on reserved forest lands and mortality that is rapidly increasing on non-reserved forest lands.

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Will Zombie Trees overrun the national forests in Idaho?  And remember, Idaho is simply a snapshot of the dynamic underway in many public forest lands across the U.S. West.  As bad as it is, unfortunately, the story does not end with a moonscape of standing dead trees.  Ultimately a lightning strike will cremate the standing and tilting remains of zombie trees, polluting expansive air sheds, further ravaging wildlife habitat, exposing streams and rivers to significant sediment loads and reduced shade, and sometimes sterilizing soils for a generation.
 
While popular science and belief stretch to accommodate and explain such ravages as part of the “natural order”, the fuel loads fanning today’s wildfires are not natural and the results rarely orderly.  Yes, thankfully there is a kind of rejuvenation in the aftermath of wildfire’s annihilation.  But in light of the destruction it seems the question is could such rejuvenation be achieved in a manner with less apocalyptic fury and lower societal cost.  Earthquakes, hurricanes, and pestilence are all natural as well.  Yet, we try to operate in a manner to mitigate their damaging effects on society, not amplify them.  As a society will we find the will to halt the advancing scourge of zombie trees?


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