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Archive for December, 2013

Within the last 20 years or so, the deep green movement has pushed people to recognize that wooded ecosystems have value intrinsically, that is not bestowed upon them by what humans get from them (be it wood products or recreation). However, it is still difficult to  justify to the average Joe, that a wood lot should remain a wood lot, and not be sub-divided or sold for timber… Or at the very least, opened up to trail users… Yet all of these things are impactful, in that they effect the way the ecosystem functions. Trails, when used responsibly can help to concentrate use, and ultimately are a best case scenario for many woodlands… Yet, many people have convinced themselves that trails are a net positive for a forest. They are not. They remove biomass for the benefit of human recreation. At best, they keep people from going out  into the woods and impacting a greater area.

That said, the other two typical alternatives, both subdividing and timbering, are surely more impactful to a mature forest, than trail building. Nevertheless, a deep green philosophy would generally argue in favor of wilderness areas, where man is just a visitor (if that), and some would go further into the realms of primitivism.

In this day and age, it hurts the cause of conservation to be anything but pragmatic. We can have our ideals, but we must recognize other interest, and negotiate for the best possible outcome in a given circumstance. Thus we must understand, the least common denominator positives of preserving our neighborhood wood lot…

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Recently, it was announced by the South Whitehall Township Board of Supervisors that the cornfield behind my house was to be sub-divided, but the wood lot that I grew up playing in, and came of age as an ecologist by studying, was to be spared. While part of me is sad to loose the farmland, I am at least relieved to be keeping the wood lot. I have always appreciated it aesthetically, and I have always appreciated what it gives us, but more than that, I see it as a home to a Red-tailed Hawk and a Great Horned Owl. A fox and a family of deer. I visit it from time to time. Each year, I measure the diameter of the two greatest Chestnut Oaks. But, I fear that the neighbors view it as a nuisance. They see wildlife as pests, and overgrowth as a tangled mess. Yet, there is a least common denominator, that rests on the tip of everyone’s tongue in this age of super-storms… Climate Change… Carbon Emissions especially.

Last year, the world emitted 35 million tons of carbon. The United States contributed 5.2 million tons of carbon. Or 16.4 tons per capita.

Why is this important? The vast majority of climatologists believe that climate change is happening, and that it is anthropogenic. In 2007 the Intergovernmental Panel on Climate Change found there to be a 90% chance that humans are contributing to climate change. (http://news.bbc.co.uk/2/hi/science/nature/6321351.stm). Even Fox News reported on the panel’s claim that an estimated sea level rise of 7-23 inches would be likely. (http://www.foxnews.com/story/2007/02/02/un-report-global-warming-man-made-basically-unstoppable/). In 2013, Environmental Research Letters found that amongst abstracts discussing Anthropogenic Climate Change, 97.1 expressed agreement with the consensus that human activity is a contributing factor.

Still, I can understand skepticism. I have never been the sort of person to take a consensus at face value. After all, one only need look back through history, and the ridiculous beliefs that have been considered a consensus are immediately apparent. So, lets go into the basic logic that goes into conclusions favoring climate change.

Scientific Fact: Carbon is an unstable element. When exposed to radiation (i.e. light from the sun) it releases heat to stabilize. This is undisputed.

Scientific Fact: Temperature data indicates a net increase in average yearly temperatures, and suggests that individual climate zones are changing as a result.

Logical Reasoning: If Carbon releases heat when exposed to radiation, it will inevitably release some into space, and some back down to earth. Thus, the higher the concentration of Carbon in the atmosphere, the more heat will be released down to earth. Since burning fossil fuels, and wood, releases carbon that had been trapped and stored in organic material, and humans burn fossil fuels on a constantly increasing basis, humans can be said to be a contributing factor to high carbon concentrations in the atmosphere. This, not climate change in and of itself (which is almost universally recognized to be occuring, since that is what 100 years of data plainly spells out), is what is debated.

If we accept this hypothesis, that the world is warming on the whole, and that is causing climates to change, and that is resultant of greenhouse gas concentrations, and the concentrations are largely a result of releasing CO2 and hydrocarbons, we come back to the main point, the importance of the neighborhood wood lot.

*  *  *

As discussed in the previous entry, the wood lot behind my house contains a biomass of 582.4 (tons per hectare). Since the lot is approximately 1 hectare, we can say the biomass is 582.4 tons. Approximately 50% of biomass in a forest ecosystem is made up of Carbon, much of it stored in the plant as Carbohydrates, formed during photosynthesis. Given that fact, the wood lot contains 291.2  tons of Carbon. Considering that there are about 75 homes in the neighborhood, with an estimated 4 people per household, there are about 300 people living in my neighborhood. Since the per capita production of tons of Carbon in a year in the United States is about 16 tons, that means that the people in my neighborhood produce roughly 50 tons of Carbon in a year.

Thus our wood lot is important in its role of mitigating the amount of carbon we produce in a year.

Admittedly I did not calculate the forest’s respiration levels, and that would likely bring us pretty close to being a net zero effect… Which, at the end of the day, is pretty good.

If we could have a hectare of forest for every 80 people in this country, we could go a long way to bringing our carbon footprint down.

If for no other reason, that is why our wood lots are important.

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I established a test plot today. I plan to measure both biomass of the plot in general and the diameter and height of a currently healthy White Ash, to try and understand forest growth. It is a hobby I have taken up, to ensure that my skills stay honed, for the next time I am out in the field.

Biomass and Carbon Sequestration:

It has long been known that plants take in CO2 gas, during photosynthesis, to create carbohydrates for the plant to use. Plants also release CO2 during respiration, but the net uptake exceeds that released during respiration, meaning that the plant stores carbon. It is said that up to 50% of a tree’s mass is carbon, and much of that carbon is stored in the extensive root systems. In order to calculate how much carbon a tree contains, first we must find out the total mass of the tree.

Mass=Volume*Density, so to find the biomass of a tree, we must first find the volume of the tree.

Since, for our purposes, trees are cones, we would find Volume with the following formula (many of you remember from geometry).

Volume=1/3*Basal Area*Height

 

 

 

Height can be found by taking a tape measure, and by standing back approximately as far as the tree is high, you use the tape measure to find the point on the tree that is about 10% of the tree. You then measure the height of that point and multiply by 10.

Basal area is found by first measuring the diameter of the tree at breast height, which is considered to be 1.6 meters. Then you plug that into the following equation (DBH/200)²  * π.

 

 

You now have volume, but you still need density. To find density, you first must identify the tree. You can then use the following site to find the density (http://www.csudh.edu/oliver/chemdata/woods.htm).

Finally your biomass equations should go as follows: Biomass(kg)=stem volume(m³)*density(kg)+40% of the answer to factor in other biomass such as roots and leaves.

If for instance, you take the White Ash from the test plot, which has a volume of 17.8 m³ and has a density of 650 Kg/m³, you get a stem mass of 11,570 Kg.

11,570*.4 = 4,628.

Total mass = 16,198 Kg or 16.2 tons of biomass.

About half of that is made up  of carbon, so about 8 tons of carbon.

 

 

For the entire wood lot, the equation looks like this.

126(m2/Ha) * 15.24(m) * 1/3=640(m3/Ha)

640(m3/Ha) * .65 (t/Ha)=416(t/Ha) * .4=166.4

416+166.4=582.4(t/Ha) of Biomass of which 291.2 tons are made up of carbon.

Just in my little wood lot (about 2.5 acres,  or 1 hectare) alone, the trees are  sequestering nearly 300 tons of carbon. When we consider carbon’s role in the greenhouse effect, (being an unstable element, it releases heat to stabilize, thus, the more carbon in the atmosphere the more warming will be expected) we can see that even a small forest can help to make a big difference.

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