Red Pine Pocket Decline - 140-403

Description: Red pine in the centre of its range naturally occurs on drier, less fertile sites, especially in central Ontario. It has been planted extensively in southern Ontario on degraded and abandoned farmland where it has stabilized the soil, provided wildlife habitat, and been a source of wood supply (poles, timbers, lumber, pulp).

In some parts of southern and central Ontario unprecedented rates of mortality in maturing red pine are challenging forest managers in their attempts to adhere to traditional management strategies and silvicultural practices. They are suffering losses of decades of investment in thinning and tending red pine plantations through sudden mortality. Likewise, wood supply is impacted. Managers face the dilemma of adhering to traditional cutting cycles and volumes (and losing volume on the stump), or liquidating large tracts of vulnerable timber, resulting in a market glut. In addition to the financial loss from stand liquidation, broader forest management objectives (e.g., natural stand conversion to a mixed forest as the red pine stand is gradually opened by thinnings) are jeopardized.

The recent wave of red pine mortality has been observed in several forms: renewed and rapid expansion of old mortality centres, appearance of new mortality centres, single-tree mortality, and windthrow of living trees with advanced root decay. Preliminary and anecdotal reports have associated the decline in Ontario with a variety of biotic and abiotic factors such as drought, root fungi, root collar weevils and bark beetles, including the non-native Pine Shoot Beetle (Tomicus piniperda). In some cases, previously described pathogens (e.g., Armillaria) are clearly associated with the mortality. In other cases, a complex of bark beetles and stain fungi has been observed, similar to a red pine decline syndrome reported in Wisconsin (Klepzig et al. 1991).

Accuracy of the growth and yield curve for red pine developed by Margaret Penner (FRP) may be affected by unexpected red pine decline occurring around the age at which CT is scheduled under management levels Intensive 1 and Intensive 2 (i.e. 55 years). An earlier report by Woods and Penner (1999) briefly discussed the impact of root disease mortality in unthinned control plots on the development of a red pine G&Y model and proposed an amended model form for thinned plantations with root disease. At the time of the development of that model only a few control plots were affected. Since then high rates of mortality in thinned plantations have been reported. Likewise, mortality in natural stands has also been observed.  

Current climate change C, which models for Ontario predict an average temperature increase of up to 3 is expected to result in dryer overall conditions due to increased evaporation and transpiration.  Anticipated environmental extremes such as drought and flooding conditions and increases in average temperature may increase vulnerability of trees to attacks from root disease pathogens and bark beetles. With even slight changes, stressed trees on some sites may be damaged beyond the point of recovery.

This research study will investigate the etiology of red pine decline in Ontario, and formulate management recommendations through consultation with project partners. The aim of the study is to identify biotic and abiotic factors associated with red pine decline and to determine if the impacts of the decline can be mitigated through alternative management practices.

The specific objectives of the study are to:

  • Identify the principal abiotic factors (e.g. drought, soil reaction, soil structure, soil nutrients) associated with red pine mortality in Ontario, with particular interest in climate change effects;
  • Identify the principal biotic factors (e.g. root pathogens, bark beetles, weevils) associated with red pine mortality in Ontario;
  • Determine whether the fungal/insect complex known as “Red Pine Pocket Decline”, recently reported in Wisconsin, is present in Ontario;
  • Assess the amount of advanced root decay present on asymptomatic trees;
  • Identify any synergetic or sequential relationships between the principal factors; and,
  • Identify causal factors that may be sensitive to management interventions.


The Project Team: John McLaughlin, OFRI


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