Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

If You Use a Screen Reader

This content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.

Pollen Source Area and Pollen Productivity: Evidence from Forest Hollows

Randy Calcote
Journal of Ecology
Vol. 83, No. 4 (Aug., 1995), pp. 591-602
DOI: 10.2307/2261627
Stable URL: http://www.jstor.org/stable/2261627
Page Count: 12
  • Read Online (Free)
  • Download ($18.00)
  • Subscribe ($19.50)
  • Cite this Item
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Pollen Source Area and Pollen Productivity: Evidence from Forest Hollows
Preview not available

Abstract

1 Although fossil pollen from forest hollows ($\approx 5$ m in diameter) is often interpreted as a record of stand-scale forest changes, this assumption has not previously been tested by comparing pollen percentages in modern sediment to vegetation from a range of sampling radii. I compared pollen in surface sediment with distance-weighted basal area of trees in radii from 10 to 100 m, to test a model (Sugita 1994) that predicts the `relevant pollen source area' for forest hollows is 50-100 m, and that about 40% of the pollen comes from trees growing within this radius. 2 Maximum likelihood estimates of pollen productivity, based on the relevant source area, are used to test for differences in species pollen productivity between a pine-dominated region in north-western Wisconsin, and a hemlock-northern-hardwoods-dominated region of upper peninsula Michigan. 3 Likelihood function scores, which measure the goodness-of-fit of the pollen-vegetation relationship based on the maximum likelihood method, show that estimates of pollen productivity $(\alpha)$ and relative background pollen loading $(\omega)$ improve as radius of distance-weighted vegetation sampling increases from 10 to 50 m. There is little further improvement from 50 to 100 m. Linear regression analysis of pollen percentages on distance-weighted basal area also shows little improvement in pollen-vegetation correlation when vegetation samples from beyond 50 m are included. Predictions of pollen percentages therefore are not improved by increasing the vegetation sampling radius beyond 50-100 m. These results support Sugita's (1994) model prediction and confirm that fossil pollen in hollows records stand-scale vegetation heterogeneity at a scale of 50-100 m. 4 Estimates of background pollen $(\omega)$ indicate that on average, only 40-50% of the pollen in forest hollows comes from trees growing within 50-100 m of the hollow. However, this is sufficient to record the stand scale vegetation heterogeneity because larger areas of vegetation are recorded as homogeneous regional background, even in patchy vegetation. 5 Relative pollen productivity of three monospecific pollen taxa (red maple, sugar maple, basswood) is similar for two regions, supporting the implicit assumption in palynology that pollen productivity is a species-specific constant. Productivity estimates of birch are similar between regions, although yellow birch dominates in one region and paper birch in the other.

Page Thumbnails

  • Thumbnail: Page 
591
    591
  • Thumbnail: Page 
592
    592
  • Thumbnail: Page 
593
    593
  • Thumbnail: Page 
594
    594
  • Thumbnail: Page 
595
    595
  • Thumbnail: Page 
596
    596
  • Thumbnail: Page 
597
    597
  • Thumbnail: Page 
598
    598
  • Thumbnail: Page 
599
    599
  • Thumbnail: Page 
600
    600
  • Thumbnail: Page 
601
    601
  • Thumbnail: Page 
602
    602