A review of precipitation and temperature control on seedling emergence and establishment for ponderosa and lodgepole pine forest regeneration

• Published in: Forest ecology and management 2016-02, Vol.361, p.328-338
• Main Authors: Petrie, M.D., Wildeman, A.M., Bradford, J.B., Hubbard, R.M., Lauenroth, W.K.
• Format: Article
• Language: English
• Subjects: Availability; Climate; Emergence; Forests; Germination; Lodgepole pine; Moisture; Pine; Pinus ponderosa; Ponderosa pine; Precipitation; Regeneration; Review
• ISSN: 0378-1127; 1872-7042
• DOI: 10.1016/j.foreco.2015.11.028

•Review of climate control of ponderosa and lodgepole pine forest regeneration.•Very few studies have focused on climate control of regeneration.•Literature and data show that intermediate temps support seedling processes.•Literature and data show that moisture availability supports seedling processes.•Additional field studies are needed to better understand climate effects. The persistence of ponderosa pine and lodgepole pine forests in the 21st century depends to a large extent on how seedling emergence and establishment are influenced by driving climate and environmental variables, which largely govern forest regeneration. We surveyed the literature, and identified 96 publications that reported data on dependent variables of seedling emergence and/or establishment and one or more independent variables of air temperature, soil temperature, precipitation and moisture availability. Our review suggests that seedling emergence and establishment for both species is highest at intermediate temperatures (20 to 25°C), and higher precipitation and higher moisture availability support a higher percentage of seedling emergence and establishment at daily, monthly and annual timescales. We found that ponderosa pine seedlings may be more sensitive to temperature fluctuations whereas lodgepole pine seedlings may be more sensitive to moisture fluctuations. In a changing climate, increasing temperatures and declining moisture availability may hinder forest persistence by limiting seedling processes. Yet, only 23 studies in our review investigated the effects of driving climate and environmental variables directly. Furthermore, 74 studies occurred in a laboratory or greenhouse, which do not often replicate the conditions experienced by tree seedlings in a field setting. It is therefore difficult to provide strong conclusions on how sensitive emergence and establishment in ponderosa and lodgepole pine are to these specific driving variables, or to investigate their potential aggregate effects. Thus, the effects of many driving variables on seedling processes remain largely inconclusive. Our review stresses the need for additional field and laboratory studies to better elucidate the effects of driving climate and environmental variables on seedling emergence and establishment for ponderosa and lodgepole pine.