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| Cultivate Green |
October 25, 2005
In this session we enjoyed presentations from David Hitchcock, an urban regional planner from The Houston Advanced Research Center, Mickey Merritt, an urban forester, and Dr. Todd Watson, a professor of Forest Service Solutions of Urban Trees at Texas A&M University. (www.houstonregionalforest.org)
David Hitchcock explained emerging carbon sequestration. Carbon sequestration is the process by which atmospheric carbon is absorbed into carbon sinks such as the oceans, forests and the soil. He detailed how trees shape the region's climate through incremental and systemic changes. David focused on Heat Island affects and how we need to look at the amount of trees needed to make a change in temperature. The current Houston strategy using public and private financing is proving to be costly, about $102 per tree. The needed ten million trees would cost over one billion dollars.
Other possibilities might include carbon markets, individual or private sector initiatives, tax strategies and possible tax incentives. Forestation projects are being broadly implemented in the U.S. More multi-national companies are aware of the carbon markets and choosing to participate. The challenges Houston faces are urban land availability, short term views on public land decisions, lack of private investors, inherent risks of the carbon market, need for federal or state restrictions on carbon/ CG emissions and lack of experience. (dhitchcock@harc.edu)
Mickey Merritt focused on the "Houston's Regional Forest" report that was released in September 2005. The report was funded by the USDA Forest Service. Trees and urban forestry can be used to reduce many of the negative effects of urban growth according to the report. The report can help state and local groups monitor and guide the development of Houston's green infrastructure.
The report was generated from satellite imagery, field data, and computer modeling. The diversity of tree species, density, health, leaf area, biomass, and location were results in the data gathered. The most common tree in the Houston regional Forest is the Chinese tallow tree which really isn't a tree. Satellite imagery was used to separate the region into broad categories of vegetation, roads, and zones of urban development. The land cover types were broken into agriculture/range lands and developed lands. Field measurements were needed to provide details that satellite imagery missed, for example, the size and species of individual trees or the location of trees with respect to buildings.
The Urban Forest Effects Model (UFORE) modeling analysis used the data generated from both the satellite imagery and the field measurements to calculate the structure, environmental effects and values of urban forest. The environmental services that trees perform using the UFORE model are, carbon storage-to quantify air pollution removal, and energy savings. Functions not analyzed by the modeling were wildlife habitat, stormwater management and flood prevention. In concluding Mickey brought to the attention of the audience the replacement cost of the region's 663 million trees. The value of those trees is $205 billion. And trees store $271 million worth of carbon , and trees generate a total of $456 million worth of environmental benefits annually! (mmerritt@tfs.tamu.edu)
Texas A & M is working on solutions to the problems urban trees face. Many trees planted in the urban forest by developers, landscapers and home owners do not have the proper space for root growth. Dr. Todd Watson's most recent research projects involve studies to develop procedures for using pervious pavement around trees and inventing methods for preserving trees in urban areas. He discussed not only the space tree roots require to thrive but the lack of compaction of soil and the type of soil needed for proper root growth.
By using pervious alternative materials for sidewalks and, parking areas additional water and minerals necessary for optimum tree growth can be made available to the trees. Dr. Watson shared examples of trees planted between streets and sidewalks, and in parking lots that that could not thrive. He also should how after both Katrina and Rita those examples were toppled easily. He also addressed the compaction problem in new home subdivisions. Many developers will scrape the topsoil off and run tractors and bulldozers over the landscape to level the ground before starting a subdivision. This action eliminates the air pockets normally available in soil for nutrients, water and air to travel to trees root system. He advises all new homeowners to aerate the ground and add good topsoil to insure their new trees will survive. (t-watson@tamu.edu)
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| Page Updated/Reviewed: 05/18/2006 1:27 PM |
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