Forest sequestration of carbon is one of many approaches to slow the rate of increase of atmospheric carbon dioxide. In this issue paper I would like to analyze the potential of tropical forest ecosystem for carbon sequestration. There are economic, political and ecological dimensions to the question but we will focus on the ecological questions.
To help you in preparing the paper I have outlined a series of questions that you should answer concisely in a 2-4 page paper. The ESM 201 notes and readings and the linked readings below should suffice for reference materials but you are welcome to search more widely. Please provide citations as appropriate. Good general summaries of the issues can be found in the Congressional Research Service 2007 Report, the US EPA website on agricultural and forest carbon sequestration (http://www.epa.gov/sequestration/faq.html), and the 2001 commentary by Scholes and Noble in Science. Technical reviews of forest net primary production and NPP in relation to forest age are provided by Clark et al. (2001), Pregitzer and Euskirchen (2004) and Keeling and Phillips (2007). Technical research papers on carbon sequestration potential of primary and secondary tropical forests include those by Silver et al. (2000), Marin-Spiotta et al. (2007) and Rice et al. (2004).
Questions to address
1) General: How significant are forests to the global carbon cycle? How important are tropical forests specifically in the global carbon cycle?
2) What are the main factors that influence the rate at which carbon is gained or lost from tropical forests?
3) How is carbon sequestration related to forest age in tropical environments?
4) What is the potential of tropical reforestation projects for carbon sequestration?
5) What are a few of the main management considerations in managing tropical forests to maximize carbon sequestration?
Management of fire risk in fire prone ecosystems of the western U.S. is one of the key issues facing public and private land managers. A number of interrelated factors have been implicated in recent increases in fire occurrence and damage, notably increased human population and ignition frequency, climate change, grazing and historic fire suppression. Some advocate large scale mechanical thinning of forests to reduce fire risk and restore historic forest stucture and composition. Others advocate control burning in both forests and shrublands to reduce fuels and fire severity. Still others advocate extensive use of fuel breaks to reduce fire spread into inhabited areas. Large differences in fire regimes among different forest and shrubland ecosystems make it difficult to develop general policies and management solutions.
Summarize in 2-4 pages some of the main ecological considerations affecting management of fire in fire prone western ecosystems by answering the series of questions listed below. Class notes and the readings that follow should suffice, but you are welcome to search more widely. Please provide citations as appropriate. Schoennagel et al. (2004) provide an overview of fire regimes in Rocky Mountain ecosystems and provide a good summary of the differences between high-, mixed- and low-severity fire regimes. Allen et al. (2002) summarize changes in fire regime in ponderosa pine forests and options for restoration. Keeley (2002) discusses fire management of California chaparral and coastal scrub ecosystems. Brown et al. (2004) discuss principles for restoration of historic fire regimes. Pyne (2004) provides a historical/social commentary on changing attitudes towards wildfire in the western U/S.
1) What is meant by the fire regime of an ecosystem?
2) What are the main controls on fire regimes in western forests and shrublands?
3) What is the meant by high-, mixed- and low-severity fire regimes. (Give an example of a forest or shrubland type associated with each.)
4) How significant is fire, both historically and at present, as an ecological factor in fire-prone ecosystems such as montane conifer forests and shrublands?
4) Compare and contrast historical and modern fire regimes in low-severity vs. high-severity ecosystems by contrasting fire regimes in ponderosa pine forests of the southwestern U.S. vs. Mediterranean-climate shrublands of southern California. How have fire regimes changed over the past century in these systems?
5) Compare fire management strategies and alternatives for ponderosa pine forests of the southwestern U.S. vs. Mediterranean-climate shrublands of southern California. (You could also consider implications of ongoing climate change in terms of the efficacy of these strategies and alternatives.)