Professional and Popular Article Summaries

   Determining Water use by Trees and Forest From Isotopic, Energy Balance and Transpiration Analyses: The Role of Tree Size and Hydraulic Lift
By: Todd E. Dawson Published: March 1995

In this scientific study, the use of water by Sugar Maples was categorized by size and age of Sugar Maples. The use of water was estimated by measuring transpiration rates and sap flow rates in large trees (9-14m tall) and small trees (3-5m tall). In a forested ecosystem, trees have a major effect on how soil and groundwater reenter the hydrologic cycle. The rate of water movement in the hydrologic cycle is determined by where the water is obtained, how the trees transport the water and how leaf stomata regulate water loss. By finding all of this information, the effect of deforestation on transpiration rates can be predicted. Deforestation is currently one of the most significant factors influencing the changing transpiration rates.  The source of water is determined between soil water and groundwater based on their hydrogen stable isotopic composition.  

The study found that large trees transpired only groundwater. These high transpiration rates were due to the hydraulic lift of the enhanced pool of transpirational water in the upper soil layers. In smaller trees, soil water was the only source of water except during the two dry periods when the trees used between 7-17% groundwater. The smaller trees had a much higher variability of transpiration rates during the growing season and also had a higher sensitivity to environmental factors that influence transpiration rates.  Larger trees however, have a greater impact on the hydrologic balance of groundwater than small trees. Though purely large Sugar Maple stands seem to have the most impact to the hydrology of the ecosystem, forested ecosystems of mixed stands with both large and small trees may have a much greater overall impact on the regional hydrologic balance. This is because in mixed stands are negatively impacting both water sources, which can therefore significantly increase total water discharge.  

http://treephys.oxfordjournals.org/content/16/1-2/263.full.pdf

   Sugar Maple and Nitrogen Cycling in the Forests of Eastern North America
By: Gary M Lovett and Myron J Mitchell Published: 2004 

Sugar Maples are the most dominant and widely distributed tree species in the northern hardwood forests. They are considered a critical species in the nitrogen cycle of forested ecosystems. Sugar Maple forests tend to have higher rates of nitrification and nitrate leaching to surface waters. This is due to the sugar maple’s critical role in promoting and regulating nitrogen levels. Because of the decrease in American beech due to competition and disease, sugar maple populations are growing exponentially. But this species composition could see a dramatic change due to acid deposition, climate change and invasive species introduction, all of which sugar maples are susceptible to. With the change of species composition approaching, there could be remarkable effects to the nitrogen cycle by forested watersheds. With this decrease in sugar maples, there will be an increase in nitrogen retention.

http://www.esf.edu/efb/mitchell/Myron%20Ref/FronEco.2.81.88.pdf

Sugar Maple Decline After Defoliation by Forest Tent Caterpillar

Authors: Wood, Dustin; Wilmot, Sandra; Allen, Douglas; Yanai, Ruth

Journal of Forestry, 2009

From 2002 to 2007 the northeast United States had large outbreaks of forest tent caterpillar. Vermont suffered 343,000 acres of defoliation in 2006 due to the caterpillar. The defoliator is active very early in the growing season and can therefore be very damaging to maple, their preferred host. Such early defoliation of the crown greatly stresses the trees and leaves them susceptible to other insects and disease.

Forest Tent Caterpillar on Sugar Maple

Ronald S. Kelley, Vermont Department of Forests, Parks and Recreation, Bugwood.org

Further stress such as drought has led to maple decline in many places including Quebec, New York, and Pennsylvania. Mortality after defoliation was most common in pole size and suppressed trees especially in even aged stands. During the outbreak some sites in New York and Vermont were defoliated up to three times throughout the growing season resulting in incredible stress. Low soil moisture, however, proved to be the largest factor increasing dieback after defoliation. Forest tent caterpillar can put enough stress on maples to cause dieback but a combination of the caterpillar, decreased sunlight (suppressed trees), and drought pose the worst threat and possible mortality.

http://sfx.uvm.edu/UVM?genre=article&isbn=&issn=00221201&title=Journal+of+forestry&volume=107&issue=1&date=20090101&atitle=Sugar+maple+decline+after+defoliation+by+forest+tent+caterpillar.&aulast=Wood%2c+Dustin&spage=29&pages=&sid=EBSCO:Agricola&pid=

   Maple Sugarbush Management and Forest Biodiversity Conservation in East Ontario, Canada
By: Kristin Clark • Robert Andrew McLeman Published: September 2011

In today’s economy, rural communities that are dependent on forested ecosystems are struggling economically and demographically. With the help of the government, there will be a boost in rural sustainable development while maintaining forest habitat. Social and economic benefits come from owning and operating small-scale sugarbushes, and at the same time conserving forested wildlife habitat. Currently there are few studies that determine the environmental impacts of sugarbushes, in particular their impact on biodiversity. By determining these impacts, a sustainable management practice of sugarbushes can be developed.  

By conducting comprehensive interviews with sugarbush operators, the current management practices were determined. In these interviews, most of the operators stated that as long as there was no negative impact to the sugarbush, they encouraged wildlife diversity. Most of the operators followed these biodiversity management principles because they were beneficial to the sugarbush and there was no real reason not to follow the principles. Overall, there are definitely ways to manage a sugarbush in order to conserve biodiversity, and most operators are already managing in these ways. In order to have the vast majority follow these principles, an incentive program should be put in to place.

http://www.springerlink.com/content/8814531805g67j71/

  Climate Change Impacts on the Sugaring Industry
By: David Biello Published: April 2009
By: Kathy Mellott Published: March 2012

The maple sugaring business is highly dependent on the weather. At night below freezing temperatures and slightly above freezing temperatures are needed during the day. The freezing temperatures at night convert the stored starch from the previous summer into sucrose; leaving the sap with 2% sugar content, meaning about 40 gallons of sap are needed to produce 1 gallon of syrup. With the impending impacts of global climate change, these temperature conditions are going to become much less frequent, which does not fair well for Sugarbush operators. Over the past few years the temperatures have slowly increased, and this past winter was the warmest winter in nearly a decade. With the increased temperatures, the sugaring season has been starting a week earlier and ending 10 days sooner, shortening the season by 3 days. The sugar content of the sap this season as well, has been unusually low; forcing the syrup to boil longer, which degrades the quality of the syrup. With these impacts to sugaring only predicted to get worse, the future is looking bleak for sugarbush operators. 

http://wwwp.dailyclimate.org/tdc-newsroom/maples/All-tapped-out

http://times-news.com/local/x2029124542/Mild-weather-not-sapping-maple-syrup-production

It’s Maple Syrup Time, So Why the Whiff of French Fries?

Evaporator Run on Used Vegetable Oil

In 2006 Vermont made one third of the 1.45 million gallons of maple syrup produced in the United States. The maple industry is a huge part of the states economics both through direct sales and tourism. Global climate change is threatening the timing of spring sap flow and the range of maple trees throughout the northeast. The article It’s Maple Syrup Time, So Why the Whiff of French Fries? published in The New York Times showcases Dan Crocker and his 2007 sugaring season in Westminster, VT.

Each spring the sap starts to flow when temperatures rise above freezing during the day and then drop again through the night. Over the past decade, however, the length of the season is growing shorter as warm weather comes faster. As the climate changes it is also pushing the range of maples northward and ultimately out of southern Vermont. Crocker decided to make changes within his operation to lower costs and protect his forest.

Crocker converted his evaporator, which turns sap to syrup, from burning regular oil to burning used vegetable oil. With the help of a government grant he installed the necessary equipment and became the first sugar maker to try veggie oil. In 2007 vegetable oil was around a dollar a gallon less expensive then regular oil. This came out to about $4,000 a year worth of savings. Also, by concentrating his sap through reverse osmosis before boiling it he used less oil.

The sugaring season each year is highly unpredictable and sugar makers must take every chance they can to lower their costs and increase production. Crocker has done just that and by staying at the front end of technological advances he has managed to stay afloat in an extremely variable business.

http://www.nytimes.com/2007/04/28/business/28maple.html?pagewanted=all