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Components of regulation of boreal forest understory vegetation : a text of fertilizer and herbivory Dlott, Franklin
Abstract
This study tests the predictions of two different hypotheses of trophic organization the 'bottom-up' and 'top-down' hypotheses respectively using plants in the boreal forest understory. The experiment manipulated plant resource levels by fertilization and consumer levels (vertebrate herbivory rate) using exclosures, and monitored the response of transplanted seedlings and the leaf area of the established vegetation. Survival and growth transplants was poorest at the highest fertilizer levels; a result not predicted by either 'bottomup' or 'top-down'. Herbivore exclosures had no significant effects on survival or growth at low or moderate herbivore densities; fertilizer addition did not increase leaf area. These results suggest that the resources added by fertilization and that the herbivores excluded were not limiting at these herbivore densities. At high herbivore densities transplant survival and growth was consistently greater inside exclosures which lends support to the 'top-down' hypothesis for seedling survival and performance, but leaf area did not significantly respond to either treatment but was greater inside exclosures especially when fertilized. A model of trophic relations in the boreal forest between understory plants, their resources and their consumers should only include herbivores as a limiting factor when their densities are abnormally high and even then the 'top-down' hypothesis is supported only from transplant data and not from existing vegetation.
Item Metadata
Title |
Components of regulation of boreal forest understory vegetation : a text of fertilizer and herbivory
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
1996
|
Description |
This study tests the predictions of two different hypotheses of trophic
organization the 'bottom-up' and 'top-down' hypotheses respectively using
plants in the boreal forest understory. The experiment manipulated plant
resource levels by fertilization and consumer levels (vertebrate herbivory rate)
using exclosures, and monitored the response of transplanted seedlings and the
leaf area of the established vegetation. Survival and growth transplants was
poorest at the highest fertilizer levels; a result not predicted by either 'bottomup'
or 'top-down'. Herbivore exclosures had no significant effects on survival
or growth at low or moderate herbivore densities; fertilizer addition did not
increase leaf area. These results suggest that the resources added by fertilization
and that the herbivores excluded were not limiting at these herbivore densities.
At high herbivore densities transplant survival and growth was
consistently greater inside exclosures which lends support to the 'top-down'
hypothesis for seedling survival and performance, but leaf area did not
significantly respond to either treatment but was greater inside exclosures
especially when fertilized. A model of trophic relations in the boreal forest
between understory plants, their resources and their consumers should only
include herbivores as a limiting factor when their densities are abnormally high
and even then the 'top-down' hypothesis is supported only from transplant
data and not from existing vegetation.
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Extent |
3472047 bytes
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Genre | |
Type | |
File Format |
application/pdf
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Language |
eng
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Date Available |
2009-02-06
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0087064
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
1996-05
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Item Media
Item Citations and Data
Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.