Progress 10/01/05 to 09/30/10
Outputs
OUTPUTS: Presentations have been given to national and regional fire and forestry conferences in California. I have also used materials from this project to teach undergraduate and graduate classes at the University of California Berkeley for the last 11 years. I have given presentations on this material to US Forest Service staff all over California including staff at the Region 5 Headquarter of the US Forest Service. No graduate student support was funded with this project. PARTICIPANTS: Scott Stephens UC Berkeley Danny Fry UC Berkeley Ernesto Franco California State University Monterey Bay Brandon Collins USFS PSW Research Station Carl Skinner USFS PSW Research Station TARGET AUDIENCES: US Forest Service Managers in the western USA. US National Park service managers in the western USA. Forest scientists in the USA. Environmental groups in the western US. Public interested in forest management. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
This project has created new knowledge that US Forest Service managers have used to develop new management guidlines for federal forests in California. This project has created new knowledge that US Forest Service managers have used to develop new management guidelines for federal forests in California. One of the key findings from this work is spatial heterogeneity in forest structure is key in producing resilient ecosystems. Forests that were investigated in this project had a fire regime that was not modified by fire suppression until 1970 and no harvesting had ever occurred in this research area. This allowed an investigation of forest structure in an area with an intact disturbance regime. I contributed to a USFS General Technical Report titled 'An Ecosystems Management Strategy for Sierra Mixed-Conifer Forests' (North et al. 2009 GTR-PSW 220). This report included many aspects of my AES project, it was a key component of it. This document is now being used throughout California to assist in the production of desired conditions on federal lands. It is having a huge impact on the state of California. Environmental groups that once were in court litigating US Forest Service projects are now working more cooperatively; this work has assisted in this transformation. Currently US Forest Service staff in the eastern Sierra Nevada are using materials from this project to assist in the development of desired conditions for this large area.
Publications
- Fry, D.L., and S.L. Stephens. 2010. Stand-level spatial dependence in an old-growth Jeffrey pine - mixed conifer forest, Sierra San Pedro Martir, Mexico. Canadian Journal of Forest Research 40:1830-1814.
- Stephens. S.L., C.I. Millar, and B.M. Collins. 2010. Operational approaches to managing forests of the future in Mediterranean regions within a context of changing climates. Environmental Research Letters 5: 024003.
- Stephens, S.L., J. Moghaddas, B. Hartsough, E. Moghaddas, and N. E. Clinton. 2009. Fuel treatment effects on stand level carbon pools, treatment related emissions, and fire risk in a Sierran mixed conifer forest. Canadian Journal of Forest Research 39: 1538-1547.
- Stephens S.L, Fry D, Franco-Vizcano E. 2008. Wildfire and forests in Northwestern Mexico: the United States wishes it had similar fire 'problems'. Ecology and Society. 13(2): 10
- Skinner, C.N., J.H. Burk, M. Barbour, E. Franco-Vizcaino, and S.L. Stephens. 2008. Long-term influences of climate on fire regimes in montane forests of northwestern Mexico. Journal of Biogeography 35(8):1436-1451.
- Stephens, S.L., R.E. Martin, and N.E. Clinton. 2007. Prehistoric fire area and emissions from California's forests, woodlands, shrublands and grasslands. Forest Ecology and Management 251:205-216.
- Evett, R., Franco-Vizcaino, E., and Stephens, S.L. 2007. Comparing modern and past fire regimes to assess changes in prehistoric lightning and anthropogenic ignitions in a Jeffrey pine-mixed conifer forest in the Sierra San Pedro Martir, Mexico. Canadian Journal of Forest Research 37: 318-330.
- Stephens, S.L., Fry, D. L., Franco-Vizcaino, E., Collins, B.M., and Moghaddas, J.J. 2007. Coarse woody debris and canopy cover in an old-growth Jeffrey pine-mixed conifer forest from the Sierra San Pedro Martir, Mexico. Forest Ecology and Management 240: 87-95.
- Fry, D.L., and S.L. Stephens. 2006. Influence of humans and climate on the fire history of a Ponderosa pine-mixed conifer forest in the southeastern Klamath Mountains, California. Forest Ecology and Management . 223: 428-438.
- Stephens, S.L., and P.Z. Fule. 2005. Western pine forests with continuing frequent fire regimes: Possible reference sites for management. Journal of Forestry 103(7): 357-362.
- Stephens, S.L., and D. R. Fry. 2005. Spatial distribution of regeneration patches in an old-growth Pinus jeffreyi-mixed conifer forest in northwestern Mexico. Journal of Vegetation Science 16:693-702.
- Stephens, S.L. and Gill, S.J. 2005. Forest structure and mortality in an old-growth Jeffrey pine-mixed conifer forest in northwestern Mexico. Forest Ecology and Management.. 205:15-28.
|
Progress 01/01/09 to 12/31/09
Outputs
OUTPUTS: My work investigating the resiliency of Jeffrey pine-mixed conifer forests in northern Baja California continues to influence forest management in California. Hugh Safford, the Regional Ecologist for USFS Region 5, told me that a new eastern Sierra Nevada plan was under development and the team working on this was using my papers from similar forests in northern Baja California as the prime source of scientific information for this effort. I also continue to speak at regional and national meetings on the results from this project. I gave presentations on this work to the Association for Fire Ecology meeting in Georgia in November 2009, and to meetings at the Plumas National Forest Headquarters in Quincy, CA. In all of these settings I discuss what we have learned from Jeffery pine-mixed conifer forests in Baja California and how this information can inform management decisions in the US. I have worked with collaborators on 3 multi-authored papers this year in addition to the paper where I am the lead author. Two of the multi-authored papers are from Jeffrey pine and mixed conifer forests in the Sierra Nevada and Northern Coast Ranges (papers 2 and 4 below) and one was an effort to supply a review of current science to USFS managers in the Sierra Nevada (paper #3). All of these studies were used in undergraduate and graduate teaching at UC Berkeley including undergraduate classes in fire science; insects, disease, and fire in forest ecosystems; beginning silviculture, and graduate classes in fire ecology. Paper #1 has been submitted for an oral presentation to the Fire Conference in Spokane WA latter this fall. My papers in PDF format are available for download from my research website at UC Berkeley and web tracking software has determined that they have been downloaded hundreds of times in the last 12 months. Outreach activities have occurred during the last 12 months including giving information from this project to UC Cooperative Extension Advisors in the northern and southern Sierra Nevada as part of the Sierra Nevada Adaptive Management Project. PARTICIPANTS: Dr. Scott Stephens, Associate Professor of Fire Science is the PI on this project. I work to set the overall research agenda and put together the research group to get the work done in northern Baja California. I continue to collaborate with Carl Skinner, Research Geographer, US Forrest Service Pacific Southwest Research Station in Redding CA., Malcolm North, Research Forester, US Forrest Service Pacific Southwest Research Station in Davis, CA., and Dr. Ernesto Franco, Centro de Investigacion Cientifica y de Educacion Superior de Ensenda, Baja California, Mexico, and California State University Monterey Bay, regarding this project. Professional development is produced each year when I use materials from this project when talking with federal forest managers in California and Oregon. I continue to be asked to come to meetings at USFS Ranger Districts to talk about this work and how it can inform current management. TARGET AUDIENCES: Efforts that deliver science-based knowledge to people through formal or informal educational programs include Scott Stephens supporting information transfer from this project to several USFS National Forests. Hugh Safford, the USFS Region 5 Ecologist, continues to create materials from this research and has discussed it with forests staff in several National Forests in California. The over arching goal of this project is to provide forest managers with information and ideas that can assist in the development of management plans, especially in federally owned areas. The research project continues to support instruction at the University of California, Berkeley, at the undergraduate and graduate levels. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Research results from the eastern Sierra Nevada in Jeffrey pine-mixed conifer forests and mixed conifer forests in the Northern Coast Ranges (papers #3 and 4 below) will assist federal forest managers in the development of management plans in these areas. Paper #4 is one of the first to quantitatively document the influences of Native American burning in California coniferous forests and how this fire regime changed with Euro-American settlement. Publication #3 has generated quite a bit of discussion in California. The authors (including Stephens) provided 3 workshops to USFS forest managers and line officers across the state that were attended by 70-150 people in each location. In many cases intense discussion was generated and I believe all parties benefited from the discussion. This USFS GTR is being used significantly in USFS forest plan revisions that are ongoing in California. The California Board of Forestry had a session of their Forest Management committee on this publication as well. Publication #1 is novel in that is reports on one of the first studies ever done to determine the probability of fire scar formation and the processes that lead to scarring. Fire scar papers have been published for at least the last 35 years but questions about the fundamental process of fire scar formation have largely been ignored. This paper determined that the time since previous fire was very important regarding the ability of a tree to actually record a fire. When the time since previous fire was less than 10 years, 10-30 years, and greater than 57 years, the probability of a tree rescarring was approximately 0.05, 0.5, and 0.75, respectively. The low probability of fire scar formation when the previous interval was shorter than 10 years was very surprising. Certainly more research is needed in this area but if other studies find similar results it will change the way in which fire scars studies are interpreted.
Publications
- (1)Stephens S.L, D. Fry D, B.M. Collins, C.S. Skinner, E. Franco-Vizcano, and T. Freed. 2010. Fire-scar formation in Jeffrey pine-mixed conifer forests in the Sierra San Pedro Martir, Mexico. Canadian Journal of Forest Research (in press).
- (2)North, M., K. Van de Water, S.L. Stephens, and B. Collins. 2009. Climate, rain shadow, and human-use influences on Eastern Sierra Nevada fire regimes. Fire Ecology 5: 20-34.
- (3)North, M. P. Stine, K. O'Hara, W. Zielinski, and S. Stephens. 2009. An ecosystems management strategy for Sierra mixed-conifer forests. US Dept. Agriculture Forest Service Pacific Southwest Research Station. General Technical Report PSW-GTR-220. 52 pages.
- (4)Skinner, C.N., C.S. Abbott, D.L. Fry, S.L. Stephens, A.H. Taylor, and V. Trouet. 2009. Human and climatic influences on fire occurrence in California's North Coast Range, USA Fire Ecology 5: 76-99.
|
Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: I continue to speak at regional and national meetings on the results from this project. I gave presentations on this work to the Association for Fire Ecology meeting in San Diego in 2007, to Conservation Biology seminar at the University of Nevada, Reno, and meetings at the Plumas National Forest Headquarters in Quincy, CA. In all of these setting I discuss what we have learned from Jeffery pine-mixed conifer forests in Baja California and how this information can inform management decisions in the US. These forests are not perfect analogs to those in the US but they can still provide important information to US managers. The Jeffrey pine-mixed conifer forests in the Sierra San Pedro Martir are the last landscape-scale mixed conifer forest that has not been harvested or experienced wide-spread fire suppression in western North America. The 2 studies published this year concentrated the effects of a wildfire that followed 4 years of intense drought and a study linking broad scale fire occurrence with regional and global climate. All of these studies were used in undergraduate and graduate teaching at UC Berkeley including undergraduate classes in fire science; insects, disease, and fire in forest ecosystems; beginning silviculture, and graduate classes in fire ecology. Presentations were given at scientific conferences on both of these studies. Carl Skinner presented information from the fire-climate work at the Landscape Ecology national conference as well. These two papers in PDF format are available for download from my research website at UC Berkeley and web tracking software has determined that they have been downloaded hundreds of times in the last 12 months. Outreach activities have occurred during the last 12 months including giving information from this project to UC Cooperative Extension Advisors in northern and southern California. PARTICIPANTS: Dr. Scott Stephens, Associate Professor of Fire Science and PI on this project. I work to set the overall research agenda and put together the research group to get the work done. I also give presentations from results from this project, write journal papers, and participate in field-work. I continue to collaborate with Carl Skinner, Research Geographer, US Forrest Service Pacific Southwest Research Station in Redding CA., and Dr. Ernesto Franco, Centro de Investigacion Cientifica y de Educacion Superior de Ensenda, Baja California, Mexico, and California State University Monterey Bay, regarding my research in northern Baja California. Professional development is produced each year when I use materials from this project when talking with federal forest managers in California. On many occasions I have been asked to come to meetings at USFS Ranger Districts to talk about this work and how it can inform current management. TARGET AUDIENCES: Efforts that deliver science-based knowledge to people through formal or informal educational programs include Scott Stephens supporting information transfer from this project to several USFS National Forests. Hugh Safford, the USFS Region 5 Ecologist, has created educational materials from this research and has discussed it with forests staff on the Cleveland, San Bernardino, Angeles, Los Padres, and Tahoe National Forests, and Lake Tahoe Management Unit of the USFS. Hugh has told me that these materials have been well received and they are making a different in how these federal lands are being managed. The research project continues to support instruction at the University of California, Berkeley, at the undergraduate and graduate levels. I also gave guest lectures to students at the University of California, Davis, and University of Nevada, Reno, during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Research results from the Sierra San Pedro Martir wildfire study in Jeffrey pine-mixed conifer forests (publication 1 below) has assisted federal forest managers in the development of management plans in similar forests in the western US. Specifically, Hugh Safford, the USFS Region 5 Ecologist, has created educational materials from this research and has discussed it with forests staff on the Cleveland, San Bernardino, Angeles, Los Padres, and Tahoe National Forests, and Lake Tahoe Management Unit of the USFS. Hugh has told me that these materials have been well received and they are making a difference in how these federal lands are being managed. I have been asked to present some of this information to forest staff at the Lake Tahoe Management Unit and will do so this year. Direct application of the concept of spatial heterogeneity in forest structure in the management and restoration of forests has occurred from this project. My studies from the forests of the Sierra San Pedro Martir have identified spatial heterogeneity in forest structure as one of the key elements in the production of a resilient forest that can incorporate fire, insects, disease, and drought without experiencing forest mortality outside a desired range. The impacts of changing climates will make the work from this area even more important.
Publications
- 1) Stephens S.L, Fry D, Franco-Vizcano E. 2008. Wildfire and forests in Northwestern Mexico: the United States wishes it had similar fire problems. Ecology and Society 13(2): 10.
- 2) Skinner, C.N., J.H. Burk, M. Barbour, E. Franco-Vizcaino, and S.L. Stephens. 2008. Long-term influences of climate on fire regimes in montane forests of northwestern Mexico. Journal of Biogeography 35(8):1436-1451.
|
Progress 01/01/07 to 12/31/07
Outputs
OUTPUTS: Analyzes were completed and papers published from 5 experiments and assessments supported by my AES project in 2007. AES funding is listed in the acknowledgement section of all 5 papers listed below in the Publications section. Three of these studies continued my work in Jeffrey pine-mixed conifer forests in the Sierra San Pedro Martir in northern Baja California, Mexico. This is the last landscape-scale Jeffrey pine-mixed conifer forest that has not been harvested or experienced wide-spread fire suppression in western North America. The 3 studies concentrated on the spatial distribution of coarse woody debris and forest canopy cover, the incidence of lightning and past anthropogenic sources of ignitions in this forest, and if this forest had a significant grass understory in the last several centuries. The remaining two papers examined the ecological effects of forest treatments designed to reduce fire hazards in Sierra Nevada mixed conifer forests. One study investigated
if non-native species benefited from the forest restoration treatments and the other examined how successful prescribed fire treatments were in producing pre-historic forest structure. All of these studies were used in undergraduate and graduate teaching at UC Berkeley including undergraduate classes in fire science; insects, disease, and fire in forest ecosystems; beginning silviculture, and graduate classes in fire ecology. Presentations were given at scientific conferences on 4 of the studies, only the Schmidt et. al 2007 paper was not presented at a conference. All of these papers in PDF format are available for download from my research website at UC Berkeley and web tracking software has determined that they have been downloaded hundreds of times in the last 12 months. Outreach activities have occurred during the last 12 months including hosting a meeting at the UC Berkeley research forest where results of this research was presented to a diverse group of managers and
scientists. UC Cooperative Extension Advisors from UC Berkeley also used information from these studies in outreach efforts in northern California.
PARTICIPANTS: Dr. Scott Stephens, Associate Professor of Fire Science and PI on this project. I work to set the overall research agenda and put together the research group to get the work done. I also give presentations from results from this project, write journal papers, and participate in field work. Dr. Rand Evett, post-graduate researcher at UC Berkeley and a scientists working on this project. Rand did the work on the incidence of lightning and past anthropogenic sources of ignitions in forests in the Sierra San Pedro Martir and also work that determined if this forest had a significant grass understory in the last several centuries. He worked part-time on this project but was paid over one person-month in the last year. I continue to collaborate with Carl Skinner, Research Geographer, US Forrest Service Pacific Southwest Research Station in Redding CA., and Dr. Ernesto Franco, Centro de Investigacion Cientifica y de Educacion Superior de Ensenda, Baja California, Mexico, and
California State University Monterey Bay, regarding my research in northern Baja California. Professional development is produced each year when I take approximately 15 people down to work in the forests in the Sierra San Pedro Martir. The group included undergraduate and graduate students from UC Berkeley, post-docs from UC Berkeley, faculty from Berkeley and other institutions (University of Nevada Reno), and forest manages from the US Forest Service and the State of California. These research trips are incredible opportunities for discussion and learning for the whole group and are an important part of my project.
TARGET AUDIENCES: Efforts that deliver science-based knowledge to people through formal or informal educational programs include Scott Stephens supporting a site visit to the forests in the Sierra San Pedro Martir by federal and state forest managers. This was a trip organized by another person from Southern California but I supplied reprints of my scientific papers relevant to the trip and suggested areas to see. I received feedback from the trip organizer and participants that the information that I supplied was very useful. The research project continues to support instruction at the University of California, Berkeley, at the undergraduate and graduate levels. I also gave guest lectures to students at the University of California, Davis, and University of California, Santa Barbara, during this reporting period.
Impacts
Research results from the two studies that examined the ecological effects of forest treatments designed to reduce fire hazards in Sierra Nevada mixed conifer forests were used in the Giant Sequoia National Monument management plan. This plan covers the majority of the Giant Sequoia National Forest and is targeted at managing the forest' many giant sequoia groves. Environmental groups such as the Sierra Forest Legacy have paid particular attention to this information and use it frequently in discussions with forest managers. The information from the coarse woody debris and canopy cover study from the Sierra San Pedro Martir (Stephens et al. 2007) was used in the formulation of the Southern Sierra Nevada Forest Conservation Strategy. This plan developed a framework for management of US Forest Service lands in the southern Sierra for conservation of the Pacific Fisher and other old-growth species. The plan is currently out for peer-review. The above studies have
influenced fire policy discussions regionally, specifically how effective fuels treatments can be designed in mixed conifer forests. Direct application of the concept of spatial heterogeneity in forest structure in forest management and restoration plans has occurred from this project. My studies from the forests of the Sierra San Pedro Martir have identified spatial heterogeneity in forest structure as one of the key elements in the production of a resilient forest that can incorporate fire, insects, disease, and drought without experiencing forest mortality outside a desired range. These concepts have been used on US Forest Service lands in southern California, similar lands in the Lake Tahoe Basin, and federal lands in eastern Oregon.
Publications
- Evett, R., Franco-Vizcaino, E., and Stephens, S.L. 2007. Comparing modern and past fire regimes to assess changes in prehistoric lightning and anthropogenic ignitions in a Jeffrey pine-mixed conifer forest in the Sierra San Pedro Martir, Mexico. Canadian Journal of Forest Research 37: 318-330.
- Evett, R., Franco-Vizcaino, E., and Stephens, S.L. 2007. Phytolith evidence for the absence of a prehistoric grass understory in a Jeffrey pine-mixed conifer forest in the Sierra San Pedro Martir, Mexico. Canadian Journal of Forest Research 37:306-317.
- Stephens, S.L., Fry, D. L., Franco-Vizcaino, E., Collins, B.M., and Moghaddas, J.J. 2007. Coarse woody debris and canopy cover in an old-growth Jeffrey pine-mixed conifer forest from the Sierra San Pedro Martir, Mexico. Forest Ecology and Management 240: 87-95.
- Schmidt, L., Hille, M.G., and Stephens, S.L., 2007. Restoring northern Sierra Nevada mixed conifer forest composition and structure with prescribed fires of varying intensities. Fire Ecology 2:204-217.
- Collins, B. M., Moghaddas, J. J., and Stephens, S. L. 2007. Initial changes in forest structure and understory plant community following fuel reduction activities in a Sierra Nevada mixed conifer forest. Forest Ecology and Management 239: 102-111.
|
Progress 01/01/06 to 12/31/06
Outputs
In the 2006 calendar year this project collected, analyzed, and published information on the fire history of ponderosa pine-mixed conifer forests in the southeastern Klamath Mountains, CA., and mixed conifer forests in northern Sierra Nevada, CA.. Neither of these areas had fire history information available before this study. This study has provided quantitative information on the fire regime in both areas including past fire frequency, seasonality, severity, and some information on past fire extent. The studies also statistically compared past fire occurrence in both sites to independent time series information on El Nino-southern oscillation and Palmer Drought Severity Index. The southeastern Klamath Mountain site was particularly interesting in regard to past fire occurrence. When the independent climate time series was compared to the years of past fire occurrence, no statistical correlation was found. It is very common for forests that once burned every 7-15
years to have past fire occurrence correlated with drought. This relationship was found in the fire history study from the northern Sierra Nevada but not in the southeastern Klamath Mountains. It seems that the forested area north of Redding CA. is an area where the influence of past El Nino or drought did not significantly impact the areas fire regime. This is an interesting finding that warrants further study. The information published from these 2 studies can assist in the development of guidelines for the management of California's ponderosa pine and mixed conifer forests.
Impacts
Information from the two fire history studies published this year from the southeastern Klamath Mountains and northern Sierra Nevada has been used by US Forest Service and US National Park Service Managers. The southeastern Klamath Mountain study was located in with Whiskeytown National Recreation Area and we provided a full copy of our data to managers at this location and also presented our information to them at 2 meetings. This information is now being used to assist in the development of desired conditions in this recreation area. The information from the northern Sierra Nevada study is being used by managers in the Plumas National Forest to assist in their definition of desired conditions. We also presented our information to managers at this National Forest and they were very interested in our results. Both studies were also presented at national fire and forest management conferences.
Publications
- Moody, T.J., Fites-Kaufman, J., and Stephens, S.L. 2006. Fire history and climate influences from forests in the northern Sierra Nevada, USA. Fire Ecology 2: 115-141.
- Fry, D.L., and Stephens, S.L. 2006. Influence of humans and climate on the fire history of a Ponderosa pine-mixed conifer forest in the southeastern Klamath Mountains, California. Forest Ecology and Management . 223: 428-438.
|
Progress 01/01/05 to 12/31/05
Outputs
No progress to report.
Impacts
No progress to report.
Publications
- No publications reported this period
|
Progress 01/01/04 to 12/31/04
Outputs
Management of woody fuels and snags is receiving increasing attention because of their impacts on potential fire behavior. Currently over 10 million hectares of forests in the western US have moderate or high fire hazards and many of them are in need of restoration. Management of snags and large fuels has also received increased attention because they provide nesting, foraging, and resting habitat for many wildlife species in North America. Studies of snag abundance have primarily occurred in managed forested ecosystems. These ecosystems have experienced decades of fire suppression and many have experienced multiple harvests. No information exists on fuel loads and snags in unmanaged mixed conifer forests in the western US. The absence of information has occurred because there are no large, coniferous forests in the western US that have not been affected by past management activities, particularly those that once experienced frequent, low-moderate intensity fire
regimes. One large forested ecosystem exists in northwestern Mexico where harvesting has never occurred and a policy of large-scale fire suppression was never initiated, the Sierra San Pedro Martir, Baja California, Mexico. This area is composed of mixed conifer forests of the Californian floristic province. One paper published in 2004 determined that average snag density was 5.10 snags/ha, (range 0-25 snags/ha) and 26% of plots had no snags. Less than average density was recorded on 71% of inventoried plots. Ten percent of the plots had a snag density greater than 10 snags/ha. Average total surface fuel loads were 15.8 tons/ha (range 0.01-159.74 tons/ha). Total surface fuel load was less than the average load in 73% of plots. Surface fuel load was greater than 18.4 tons/ha on 24% of plots, and greater than 36.8 tons/ha on 8% of plots. High variability characterized all snag and fuel attributes measured in this Jeffrey pine-mixed conifer forest. This high amount of variability is
probably the result of the relatively intact frequent surface fire regime and because no harvesting has occurred in this forest. The patchy distribution of snags and fuels observed argues against the application of uniform targets for snag retention and fuels across similar US forests. An improvement in management guidelines would be to manage for snag density and fuels over moderate spatial scales (100s of ha) instead of on per ha basis. This would enable managers to meet standards by maintaining high snag densities and fuel loads over only a portion of the forested landscape. Most US Forest Service management goals call for average characteristics (such as snag density and fuel loads) to be created at the stand level, replicated for all stands across very large spatial scales. Information from this study suggests that we must include more variation in our desired future conditions. Heterogeneity is very common in the forests of the northwestern Mexico and US forests with similar
vegetation, soils, and fire regimes would also have also included this variation.
Impacts
My recent publication on snag and fuel structures from Jeffrey pine-mixed conifer forests in Northwestern Mexico has provided fundamental information on forest dynamics. Information from this work could be used to improve federal (e.g. US Forest Service) and state forest restoration objectives, especially in pine dominated forests that once experienced a frequent, low-moderate intensity fire regime before fire suppression. Most US Forest Service management goals today call for average characteristics (such as snag density and fuel loads) to be created at the stand level, replicated for all stands across very large spatial scales. Information from this study suggests that we must include much more variation in our desired future conditions. Heterogeneity is very common in the Jeffrey pine-mixed conifer forests of the northwestern Mexico and US forests with similar vegetation, soils, and fire regimes would also included this variation before they were harvested and
subjected to decades of fire suppression.
Publications
- Stephens, S.L. 2004. Fuel loads, snag density, and snag recruitment in an unmanaged Jeffrey pine-mixed conifer forest in northwestern Mexico. Forest Ecology and Management 199: 103-113.
- Stephens, S.L., D. Piirto, and D. Caramagno. 2004. Fire regimes and resultant forest structure in the native Ano Nuevo Monterey Pine (Pinus radiata) forest, California. American Midland Naturalist 152: 25-36. (previously submitted as in press in 2003 but volume and page numbers missing)
|
Progress 01/01/03 to 12/31/03
Outputs
GSY=0 Uncertainty in desired future conditions has complicated forest restoration in the western United States. Many federal and state agencies have defined pre-historical ecosystem structures as their primary restoration objective. A debate continues about how, where, and to what extent natural variations or reference conditions derived from historical ecology should be applied to land management. Still, there is a building consensus that, at a minimum, it is useful to know and understand the past to manage ecosystems properly for the future. No crossdated fire history information exists from mixed conifer forests from the north-central Sierra Nevada or from Monterey pine forests from coastal California. The nearest published fire history information to the north-central Sierra Nevada is from mixed conifer forests from the southern Cascade mountains and southern Sierra Nevada. There are no published studies that have estimated fire return intervals or investigated
the effects of fire on forest structure in native Monterey pine forests. The objective of my research program was to reconstruct past fire regimes in these 2 areas using dendrochronology. Estimates of past fire frequency, seasonality, extent, and possible relationships with climate are examined. The land-use history of the study areas were also examined to aide in explaining past fire occurrence. In mixed conifer forests in the north central Sierra Nevada, fires were recorded between 1649 and 1921 and median point fire intervals, composite fire intervals at the 3-5 ha spatial scale, and composite fire intervals at the 9-15 ha spatial scale were 9-15, 6-14, and 5-10 yr. The seasonality of past fires in the north-central Sierra Nevada differs from that reported elsewhere, with the majority of fires occurring in latewood. Superposed epoch analysis determined that widespread fires were significantly correlated to droughts the year of the fire, and in some cases, to a significantly wet
year before the fire year. In our work, we present fire statistics at several spatial scales and encouraged others to do so. If all fire history research reported fire statistics at similar spatial scales it would allow for robust comparisons between diverse locations. Monterey pine forest had average mean fire return intervals of 11.2 - 20.1 years. Fifty-one percent of the Monterey pine trees sampled in our study regenerated within five years of three mixed severity fires. This was well below the predicted value of 75 percent that was based on the literature and life history characteristic of Monterey pine. A fire in 1948 produced the largest Monterey pine regeneration episode and this fire was verified by written records. Monterey pine forests are multi-aged and have a great amount of spatial heterogeneity, attributes common in mixed severity fire regimes. Many have assigned Monterey pine forests to a high severity fire regime, our work did not support this designation.
Impacts
My recent publications on the fire-climate-forest structure interactions have provided fundamental information on forest dynamics from areas that have been little studied. My work has encouraged other fire history researchers to present fire statistics at several spatial scales. If all fire history research reported fire statistics at similar spatial scales, it would allow for robust comparisons between diverse locations, something that is very difficult to do today. Information on the forest dynamics of Monterey pine is the first ever published. Research on Monterey pine has focused on its ecological and timber properties in areas outside North America and the trees' response to diseases and insects.
Publications
- Stephens, S.L., and Collins, B.M. 2004. Fire regimes of mixed conifer forests in the north-central Sierra Nevada at multiple spatial scales. Northwest Science 78:12-23.
- Stephens, S.L., Piirto, D., and Caramagno, D. 2004. Fire regimes and resultant forest structure in the native Ano Nuevo Monterey Pine (Pinus radiata) forest, California. American Midland Naturalist (in press).
|
Progress 01/01/02 to 12/31/02
Outputs
GSY=0 An extreme drought has occurred in the Jeffrey pine-mixed conifer forests in northwestern Mexico in the last three years. In the summer of 2002 we re-measured all snag plots to determine how climate is affecting tree mortality. We also removed a small cross-section from each standing snag in all of our plots to determine the exact year of death. These materials are presently being cross-dated using standard dendrochronology methods. Information on forest regeneration was also collected. A transect with a total length of 6 km was installed in Jeffrey pine-mixed conifer forests and each forest patch that included a minimum of three trees above 2.5 cm DBH (diameter at breast height) in an area of 7 x 7 meters was inventoried. Measurements taken include patch area, patch shape, aspect, diameter of all trees in the patch, average height of trees inside the patch, average height of trees outside the patch, and in one third of the patches increment corers were removed
to determine tree age. A lightning caused wildfire occurred in a Jeffrey pine forest in the late spring of 2002 and we sampled all trees within the fires perimeter for bark char height, scorch height, and incidence of forest insects. The national park fire-fighters extinguished the fire at approximately 4 acres in size but this is the largest fire to burn in the upper plateau for 15 years. The information on forest mortality will allow us to estimate the severity of this fire and it can provide information on the severity of lightning-caused fires in areas that have never been logged or had a long-standing policy of fire suppression (suppression began in this area of northern Mexico only twenty five years ago). Work continues on analyzing and summarizing the spatial data taken on the 4 hectare stem map and our fuels and forest structure information. These project components are moving ahead and I will submit publications on them in the next 12-18 months
Impacts
The recent publication on the fire-climate interactions in the forests in the Sierra San Pedro Martir has provided fundemental information from an area that has been little studied. It was also able to provide critical information to the current debate on dendrochronology based fire history research. Two recent papers have challenged the interpretations of such investigations without providing strong data to support their findings. This study was able to move the science of dendrochronology forward.
Publications
- Stephens, S.L., C.N. Skinner, and S.J. Gill. 2003. A dendrochronology based fire history of Jeffrey pine-mixed conifer forests in the Sierra San Pedro Martir, Mexico. Canadian Journal of Forest Research (in press).
|
Progress 01/01/01 to 12/31/01
Outputs
GYS=0 Research accomplished in the last year includes measurement of forest composition and structure using a systematic design of nested plots. Live trees were inventoried using 0.1 ha circular plots and all trees greater than 0.4 cm at DBH were measured for DBH and species. From the same plot center a 0.25 ha circular plot was established to measure the DBH and species of all snags. Species of snag was determined from the bark characteristics; snags without bark were classified as unknown. In addition to species and DBH a decay class was recorded for each snag (Cline et al. 1980). 49 of the nested plots were installed following a systematic grid design with 200 meters between plots. In one-fifth of the area (selected randomly) plots were installed every 25 meters. This was done because initial spatial statistics determined some fuel and forest characteristics might have spatial auto-correlation. If auto-correlation exists spatial models (kirging) will be developed
to model forest structure. A separate 4 ha plot (random location) was established in a Jeffrey pine-mixed conifer forest to determine spatial regeneration patterns and if regeneration is correlated with past fire, climate, both, or neither. In this plot the X and Y coordinates of all trees and seedlings was measured and all trees above 5 cm DBH were bored to determine tree age using cross-dating. All cores have been cross dated and destructive sampling of 25 small trees was done to determine the number of years to reach a height of 15 cm (height where all trees were cored). 95 fire scars were sampled from this area to determine the years of past fire occurrence using cross dating. Surface and ground fuels were sampled at each plot using the line intercept method. Using the plot center, three transects with random directions were installed. Ground fuel loads will be calculated by using appropriate equations developed to predict fuel loads in mixed conifer forests. Snag and dead and
down woody materials were sampled to determine the year of death. Small cross-sections were taken with a chainsaw and brought back into the lab for cross dating. The precise year of death will be determined and a forest mortality rate computed. Tree mortality will be analyzed to determine if it is correlated with past fire, climate, both, or neither. This work is designed to quantify snag and dead and down woody fuel dynamics (recruitment process, longevity, species). These elements provide critical habitat for many birds, insects, and small mammals and there is currently no information on dynamics of dead wood from forests with largely intact disturbance regimes. Descriptive statistics of all plot data will be done (basal area, density, average quadratic mean diameter, fuel loads, snag densities). In addition, spatial analysis of all forest structure data will be performed Spatial data taken from the 4 ha plot will be analyzed to determine if regeneration patterns (clumped, uniform,
random) and if regeneration is correlated with past fire, rainfall, both, or neither.
Impacts
Information from this research can assist in the development of sustainable prescriptions for the management of California's mixed conifer forests that are widely distributed (over 1 million ha). This research will also quantify fundamental ecosystem processes (fire, climate, insects, disease) and their interactions in an unmanaged forest that occurs no place else in Western North America.
Publications
- No publications reported this period
|
|