|Forest Investment Account (FIA) - Forest Science Program|
|FIA Project Y081240|
|Sustainable management of the ponderosa pine parkland ecosystems in the Thompson River watershed after the mountain pine beetle epidemic|
|Project lead: Vyse, Alan (Thompson Rivers University)|
|Author: Vyse, Alan|
|Subject: Forest Investment Account (FIA), British Columbia|
|Series: Forest Investment Account (FIA) - Forest Science Program|
|Almost all of the discussion about the current mountain pine beetle (Dendroctonus ponderosae) epidemic has focussed on the lodgepole pine stands in the interior of the Province. This is hardly surprising considering the scale of the epidemic and its likely social and environmental effects. However the same epidemic is also ravaging the ponderosa pine (Pinus ponderosae Dougl. Ex Lawson. var. ponderosae) stands of the southern interior. In the Thompson River drainage, for example, mortality levels of 90% in pine parkland stands are common. And within the boundaries of the City of Kamloops, staff have estimated that 75% of the mature pines have been lost already. |
Drought in 1998 and 2003 has also caused extensive mortality, especially in young stands on the forest/grassland edge, and may have contributed to the beetle mortality. Extensive mortality from pine beetle epidemics is not new in North America or B.C. Oliver and Ryker (1990) cite evidence of large scale outbreaks in the Black Hills of Dakota at the turn of 19th century and other outbreaks on the front ranges of the Rockies. In BC, Mulholland (1937) reported on the widespread loss of mature pine as a result of an epidemic in the mature yellow pine stands throughout its range ion the province. Richmond (1982) provides details of an epidemic in the Nicola River watershed, which ended in 1935.
Although, ponderosa pine stands do not have a high timber value at this time and no active forest management has taken place for decades, this was not always the case. In the early part of the last century, overgrazing was common, and ponderosa pine (variously called yellow, bull and jack pine) was intensively exploited for many uses, including railway ties, construction lumber, and boxes for the fruit industry. Whitford and Craig (1918) report on extensive and heavy use of the ponderosa pine stands in the province and this continued into the 1930’s (Arsenault et al. 2001). In the 1950’s the B.C. Forest Service issued a Stand Management Guide (B.C. Forest Service undated) which detailed stand treatments for the yellow pine forest type. Since then however there has been little timber management action. Grazing has been widespread in the ponderosa pine forest for 150 years and continues to the present although at a diminished level. Today the stands have high value for recreation, whether active, in the case of mountain bike riding and hiking, or passive, as part of the backdrop to urban areas and recreational properties in the Thompson River system. The stands also have high ecological value as habitat for an unusual assemblage of dry forest and grassland species, including several species at risk, and this value is increasing as the habitat dwindles under pressure for urban, agricultural and recreational developments. Mature stands of Ponderosa Pine provide breeding habitat for a broad community of bird and animal species. Three key groups -nuthatches, woodpeckers, and diurnal owls- constitute primary and secondary cavity nesters that rely to a greater or lesser extent on the forest type : Pygmy Nuthatches, Pygmy Owls, and Lewis’ Woodpeckers. The nuthatch is of particular interest because of its reliance on Py during all seasons for nesting cavities, an over-winter food supply, and winter roosting cavities.
The current beetle epidemic in the ponderosa pine stands (which involves Dendroctonus ponderosae primarily but also includes significant attacks by Dendroctonus brevicomis and Dendroctonus valens ) is creating a great deal of uncertainty about future management. With the high level of mortality, major changes in the ponderosa pine ecosystem are inevitable. From the information available at present it is not clear if the ecosystem will return to forest, or revert to grassland, if no management takes place. The current policy of “no management” is no longer valid. Pressures for active management are growing, with initial efforts taking place on a small scale, focused on fuel management adjacent to urban areas, and forest encroachment. There is also concern over species at risk and non-native species invasions, especially in the Provincial and Municipal parks, and these concerns may conflict with suggested management interventions. A wide range of questions are being asked but there is a very limited scientific foundation for providing answers. Much of the information available comes from the US Forest Service publications (Baumgartner and Lotan 1988; Oliver and Ryker 1990) which deal with ponderosa pine ecosystems far to the south. Some authors have suggested that these forests are "fire maintained" and that a combination of fire suppression and a lack of management action to counter the effects of fire suppression have led to unsustainable stand structures and away from the dynamic equilibrium maintained by frequent fires (BC Ministries of Forests and Environment 1995). Based largely on forest fire history studies in the ponderosa pine forests of the American Southwest, the supposed sustainable structure is characterized by extensive areas with low crown closure, widely spaced large trees, lush grass understory, and few tree seedlings or woody shrubs. Fire suppression is claimed to have changed the forest structure of local stands by increasing the density of small stems, and changing species composition as it has done in the South west (Covington and Moore 1994; Moore et al. 1999). Tree invasion of grassland (Strang and Parminter 1980), increased fuel loading leading to more extreme fire events, and pest outbreaks have also been attributed to the management failure to maintain this structure. Arsenault and Klenner (2005) present an alternative view of a mixed severity, non-equilibrium fire regime in the dry forests of British Columbia. They state that: "historical conditions like today were quite variable and therefore choosing a reference condition for ‘ecological restoration’ is virtually impossible. p.14."
The project we propose will supply a foundation for understanding the short and long term ecological impact of the mountain pine beetle on the current ponderosa parkland stands, the disturbance history in these stands, and what target stand or stands should be the focus of future sustainable management. We will concentrate on easily measured ecosystem variables such as tree mortality, stand structure, regeneration, snags, coarse woody debris, presence and abundance of key bird species, and ground vegetation including non native species. Long term plots will be established for future monitoring, and will build on those already established by the Ministry of Environment’s NDT4 monitoring project and the Ministry of Forests and Range’s projects at Opax Mountain and Isobel Lake (Klenner and Arsenault 2006). First Nations use of the plants in these forests has been extensively researched (Turner et al. 1990) but their views of the effect of the epidemic and its effect on their interests have not been explored and recorded.
|Related projects:  FSP_Y092240,  FSP_Y103240|
|Contact: Vyse, Alan, (250) 372-8607, email@example.com|
|Executive Summary (15Kb)|
To view PDF documents you need Adobe Acrobat Reader, available free from the Adobe Web Site.
Updated August 16, 2010
Please direct questions or comments regarding publications to For.Prodres@gov.bc.ca