Use of a smoother to forecast occurrence of epiphytic lichens under alternative forest management plans
- Author:
- McCune B., Berryman S.H., Cissel J.H. & Gitelman A.I.
- Year:
- 2003
- Journal:
- Ecological Applications
- Pages:
- 13(4): 1110-1123
- Url:
We used habitat models to forecast the frequency of occurrence of epiphytic
lichen species in a forested landscape under two alternative plans: a literal application of
standard prescriptions in the Northwest Forest Plan and a plan patterned in part after natural
disturbance regimes. The plans were evaluated for the Blue River watershed in the Cascade
Range of Oregon, USA. We used two model types: logistic regression and an ecological
neighborhood model using a form of nonparametric regression (SpOcc; Species Occurrence
Modeler). Both logistic regression and SpOcc successfully estimated the occurrence of the
lichen Lobaria oregana in the current landscape, based on elevation and structural classes
of forests. Structural classes were defined by combinations of (1) overstory retention of
remnant trees, (2) young cohort age, and (3) stream position (upland vs. riparian). Lobaria
oregana rapidly diminished in frequency in the landscape at elevations above 900-1000
m. Young, even-aged stands had little or no Lobaria oregana. Most of the other structural
classes, however, were very similar in frequency of Lobaria. The differences in lichens
between retention levels and between mature and old growth stands were very small compared
to the differences with respect to elevation and clearcutting. Similar results, with
varying importances of elevation and forest structure, were obtained for most of the 20
species with the strongest models. Many of these species were associated with old growth,
and many were forecasted to be more frequent under either management plan than in the
current landscape. This is a likely response to the reduction of even-aged management in
this landscape. We recommend using SpOcc for flexible nonparametric fitting of species
relationships to a multivariate habitat. SpOcc avoids the need to specify response functions
and, because it is multiplicative rather than additive, automatically models responses to
interactions among predictors.
Key words: ecological neighborhoodm odel; epiphytes;f orest planning; habitatm odel; lichens;
Lobariao regana;n onparametricsm oothing;N orthwestF orestP lan; PacificN orthwest( USA);r iparian
forests.
- Id:
- 11938
- Submitter:
- zdenek
- Post_time:
- Friday, 30 January 2009 11:25
