Stand Damage Percentages

[AfraidChocker]

How does a professional forester calculate stand damage percentages on a year by year basis?

I have a Forest management Plan, built a data base around it, but now I am trying to make it so that it is constantly updated year by year. I know with growth, here in Maine it ranges between 1/2 to 3/4 of a cord per acre per year, so that is easy to calculate, and obviously I know what I harvest from it from wood, but the last part of the equation is calculating natural stand damage. I realize no one can factor weather phenomenons, but is there a general rule where say a 1/4 of a cord per acre of wood is factored in as wind throw, rot or wildlife trees? Or is it a 1/2 cord? A cord?

My goal is to have a fairly accurate idea of what my wood lot holds for value at any given time, and not every 10 years as my Forest Management Plan is updated.

[WDH]

I would figure natural mortality at about 3% per year, not including catastrophic events like tornado or hurricane.   

[AfraidChocker]

That seems a lot easier. My Forest Management Plan was done under USDA-NRCS ruling so the Forester had to do a lot of soil work regarding it. I was trying to use the "wind throw" data on a given soil, but was probably overthinking it.

Do you factor in the species of wood, for instance Balsam Fir which cannot tolerate as much weather versus that of say White Pine that has a tap root that tickles Lucifer in his rather warm lair?

[clearcut]

Individual tree and overall stand mortality are difficult to model well. So many factors can come into play. Mortality in a well managed stand can range from none, to 1 shaded out tree, to complete loss due to a catastrophic event. The models have to account for that range of possibilities, and over a large region.

Growth and yield models, such as the USFS Forest Vegetation Simulator (FVS) are used to predict how "forest vegetation will change in response to natural succession, disturbances, and proposed management actions. Extensions to the base model are available to assess the effects of insects, disease, and fire."

Models such as the FVS are generally used over a larger area, company-wide, or national forest wide area. They also tend to be used over a longer time horizon, 5, 10, 20, or hundreds of years.

The USFS monitors forest conditions and published Forests of Maine, 2014 which gives an overall estimate of the state and breaks down growth and mortality by species.

     http://www.fs.fed.us/nrs/pubs/ru/ru_fs52.pdf

For a smaller property, observation is your best tool. Walk around and look. Are the trees healthy and growing. For those that are not, what is the cause - crowding, shade, insects, disease etc. Is it the small trees, that have very little impact on the overall volume, or are the larger trees being killed by a pathogen (eg. hemlock adelgid) and need to be salvaged to retain value. Then you can modify your plan to account for these impacts.

Look at last year's mortality, that is your best approximation of this year's mortality barring management or environmental changes.

[AfraidChocker]

I was not so much concerned with logging, my woodlot is always in some sort of logging operation anyway, it was merely from a monetary point of view. The forest grows trees at a certain rate, harvesting is done (which is easy to calculate), and then there is mortality for a variety of factors. I was trying to use the seedling mortality rates based on soil conditions, as well as wind throw data also based on soil conditions so that with all three areas:

Growth
Harvest
Stand Damage

I can get up-to-date data on what my wood lot contains at the click of a mouse. She did that with a mapping tool developed in New Hampshire, and the use of a prism. My current Forest Management Plan was started in 2014 and extends until 2024, the management plan was more wordy then filled with hard data which I prefer. In short, I am a numbers type of guy!

I have had to redo the plan in some aspects only because the way it was written up was not done in a real world sort of way. I am not blaming her, she is an excellent forester, but she had to make a plan the also fit the USDA-NRCS grant I was given for the Forest Management Plan as well as just doing so in Forester speak. For instance, she lists individual species of hardwood trees. That is good data to know, but it matters little to me if it is beech, ash or cherry...that is a load of hardwood logs, firewood or hardwood pulp. I just used the data she provided to condense some of that stuff down so that I can look at my individual stands and know what the potential is.

I really am looking to have the best of both worlds. I have a really good plan to care for the forest to improve it for longevity, but I also need one to generate a numeric value of what my forest is worth; as a whole and also by stand.

For instance, I have Stand 7 which is 6 acres, contains about 80 cord of wood and is on good, well drained soil right next to my highest production field. None of this is a surprise, rock walls indicate it was a field built around 1830 as well. Based on the data my forester has generated, and the data I have compiled, I can compare the two and make an informed decision on what is better fiscally; for it to remain a forest, or clear cut it, stump it and turn it back into field. Even better, I can get a really good idea of what I can get for income from that stand and compare it against developments expenses of making it into a field again. That is kind of nice! Now apply that logic to the entire woodlot and you can quickly see the benefit.

Thanks so much for your help. It is so tricky to calculate!!

[Dobie]

I would figure natural mortality at about 3% per year, not including catastrophic events like tornado or hurricane.

If the normal growth rate of a well managed woodlot(hardwood) is 2-4% I would think the mortality rate would be much less.


Perhaps someone could shed some light on this.

[curdog]

I would figure natural mortality at about 3% per year, not including catastrophic events like tornado or hurricane.

If the normal growth rate of a well managed woodlot(hardwood) is 2-4% I would think the mortality rate would be much less.

Perhaps someone could shed some light on this.

Someone else may be better able to explain this than me but I'll shoot at it. A given acre has a certain carrying capacity, meaning that it can grow a certain amount of wood given nutrients ,moisture.  As the trees grow and put on more volume, the land can still support the same set amount.  Some trees win,some loose. A young stand may have thousands of trees per acre, but a mature in the low hundreds. Your volume of wood would be about the same, but it's just distributed differently.

[AfraidChocker]

I mean no disrespect in this reply whatsoever, but in plugging in the 3% for natural loss I came up with a pretty high amount. In my case I am only talking a few hundred acres and know just about every square foot of it, and it did not seem accurate. I cut it back to 2% and the numbers generated seemed better, but still was pretty high. At 1%, to me anyway, it seemed spot on.

I am fortunate in that my Forest Management Plan is soil based, so every stand is mapped by soil types and with those soils it is broken down into:

Erosion Hazzard
Equipment Limitations
Seedling Mortality
Wind throw Hazzard

These are then broken down into classes:

Slight
Moderate
Severe

What I ultimately did was use Excel to make a data table and assign percentages to the classifications of each stand. I assigned it 1% for each limitation. Stand 3 on my farm for instance, is rather wet and consists of BvB soil. Equipment Limitations is useful to know, but has no bearing on productivity so it was struck from the equation. However even on the best of soils a forest is going to experience some sort of stand damage so every stand was given a 1% loss as a starting point. So for Stand 3, my worst stand it received an overall score of 3%. (1% for stand stand damage, 1% for seedling mortality, and 1% percent for being prone to wind throw).

BvB Soil
Erosion Hazard: Slight
Seedling Mortality: Severe
Wind throw Hazard: Severe

Ultimately as Clearcut mentioned, it all boils down to accuracy on the ground. My forester has said "she had to put on her big girl pants and hike through stand 3" which is another way of saying, what I generated for figures seems accurate. With that confidence I applied what I knew was accurate to the rest of my Forest Management Plan.

There was a few more calculations I did to break it down by cords and tree species, and I am pretty happy with the results.

[AfraidChocker]

Just for fun, and completely separate from what I did in the post above, I took my total growth, what has been harvested since 2014, and stand damages; and charted them month by month from January 2014 when my Forest Plan was put into effect until January 2025 when it needs updating...a 10 year period...just to see what I would get for an overall net gain.

I did it month by month because growth only occurs in Maine from April to October, while harvesting levels varies by month, while stand damage occurs all year long.

I was pleased with the overall uptick in volume despite some dips and rises. Now I am going to apply this same tactic to my individual stands to get a better idea of what my individual stands will look like in ten years as well. Better yet, I can plug in different logging scenarios and see what the outcomes are.

Overall I think it will be a good management tool that will enable me to make some really good forestry-farm decisions.

[WDH]

I think that 3% mortality would be OK for a stand at full maturity looking at perpetuity.  However, in the early part of the growth cycle, I agree that 3% is too high. 

[AfraidChocker]

I think that 3% mortality would be OK for a stand a full maturity looking at perpetuity.  However, in the early part of the growth cycle, I agree that 3% is too high.

You bring up a very good point and that is maturity.

That is what I am struggling with now; not so much with mortality issues, I think I have gotten that squared away, but dealing with the conversion of pulpwood to saw logs. On another thread I mentioned a mantra my Grandfather taught me and that was "always cut the junk wood". I have been doing that for 25 years with very few exceptions so we have a lot of saw logs, and even more that converts to saw logs every year.

That is a logistical nightmare because while the growth rate is slower, the mortality rate is higher, but the overall VALUE of the wood is so much greater. That is the issue I must work on now. It is hard for me because I grew up old school where trees had to be rather large in size to be considered a saw log. Today, where a 6 inch top is often considered a saw log, I simply shake my head.

My forester did break things down into pulp/saw logs, but it was not very accurate. She based prices on average stumpage prices over the entire state, whereas I log my own wood and often saw my own lumber. Again, I am not criticizing her work as a forester; I honestly think she is the best in the state, I am just not the average wood lot owner.

[mesquite buckeye]

Just some thoughts. What happens if another EAB, Dutch Elm disease, or chestnut blight hits your stand? You are then faced with near 100% loss of that species. Please consider infrequent, but devastating events in part of your figures. Hurricanes, fires, droughts, tornados and the like are not frequent, but over what is probably close to an 80-100 year cycle become more important.

We had severe drought in the midwest a few years ago. I lost between maybe 5-80% of the stand in my forest depending on the soil and type of tree. The oaks and hickories were particularly hard hit. The red cedars seemed almost unaffected. Of course the next year we got a severe ice storm that split, bent and broke off lots of the cedars.  :( :( :( Some of the trees that got hurt are still dying, so damage may not be apparent immediately. I'm guessing my overall losses are close to 10%. A lot of it was in the biggest trees. :(