Disentangling the effects of area, energy and habitat heterogeneity on boreal forest bird species richness in protected areas

作者：Honkanen Merja^*; Roberge Jean Michel; Rajasarkka Ari; Monkkonen Mikko

来源：Global Ecology and Biogeography, 2010, 19(1): 61-71.

DOI：10.1111/j.1466-8238.2009.00491.x

• Birds
• Finland
• habitat heterogeneity
• productive energy
• solar energy
• species-area relationship
• species-energy relationship
• species number

Aim
One of the few general laws in ecology is that species richness is a positive function of area. However, it has been proposed that area would merely be a proxy for energy. Additionally, habitat heterogeneity has been found to be an important factor determining species richness. Yet the relative importance of those relationships is little known, and it is still unclear how they are brought about. We aimed to dissect which factors drive the species richness of boreal forest birds, and to identify the most probable mechanisms.
Location
Forested protected areas in Finland.
Methods
Using bird line census data collected in 104 protected areas, we ran simultaneous autoregressive models to explain the species richness of forest birds. We explored the value of forest area, tree volume, tree growth, mean degree days and habitat heterogeneity as explanatory variables and used the species richness within different species groups, based on the predictions of hypothesized mechanisms, as a response variable.
Results
Energy, rather than area or habitat heterogeneity, seems to be the main driver of species richness in boreal forest birds. More specifically, productive energy was a better predictor of total species richness than solar energy. Among the tested hypothetical mechanisms, the sampling hypothesis received strong support. After accounting for sampling, solar energy had an effect on species richness.
Main conclusions
As productive energy, such as tree volume, is associated with species richness, high-energy areas should be prioritized in forest conservation planning. Reductions in productive energy may first lead to the disappearance of the rarest species due to the random sampling process. Climate change may result in increased species richness due to increasing amount of productive and solar energy in forests. However, the range shifts of bird species may not be fast enough to keep up with the temperature increases.

• 出版日期2010-1