The contribution of spawning Pacific-salmon to nitrogen fertility and vegetation nutrition during riparian primary succession on an expansive floodplain of a large river
Floodplain vegetation communities are mosaics of succession stages caused by erosion/redeposition as river channels migrate throughout their floodplains. Typically, plants colonizing alluvial deposits are severely N-limited, but N accumulates during succession, and this process determines long term...
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University of Montana
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ftproquest:oai:pqdtoai.proquest.com:3310436 2023-05-15T16:59:28+02:00 The contribution of spawning Pacific-salmon to nitrogen fertility and vegetation nutrition during riparian primary succession on an expansive floodplain of a large river Morris, Michael Roger 2008-01-01 00:00:01.0 http://pqdtopen.proquest.com/#viewpdf?dispub=3310436 ENG eng University of Montana http://pqdtopen.proquest.com/#viewpdf?dispub=3310436 Ecology thesis 2008 ftproquest 2021-03-13T17:39:28Z Floodplain vegetation communities are mosaics of succession stages caused by erosion/redeposition as river channels migrate throughout their floodplains. Typically, plants colonizing alluvial deposits are severely N-limited, but N accumulates during succession, and this process determines long term fertility. The Kol River (Kamchatka, RU), received large annual N-subsidies from salmon and we sought to determine how salmon-N contributed to fertility during succession. We constructed a vegetation chronosequence model and made N-fertility measurements within replicate succession stages before, during and after salmon runs. Natural abundance of 15N was used as a tracer of salmon-N. We found that new alluvial deposits were N-poor, containing <200 kg-N ha-1 (to 10cm). However, soil-N increased more than 10X within 30 years and soils were N-rich henceforth. Net N-mineralization on young alluvial bars only provided a small fraction of the colonizing forest’s N requirement, whereas soils in older forests provided abundant N. Negative correlation between foliar C:N and soil N during the first 20 years of succession indicated that the youngest succession stages were N-limited. The salmon run commenced in midsummer and caused river water N to increase 3X. Subsequent late season flooding deposited an average of 25 kg-N ha -1 as salmon carcasses onto young alluvial bars during 2006, but deposition rates were 10 to 30X higher on other years. The N-pulse created by decomposing salmon on young alluvial bars was brief because subsequent flooding flushed these coarse soils, but colonizing willows assimilated N rapidly during this time and high foliar δ15N (3 to 5‰) confirmed that salmon were a major N-source in early succession. Foliar δ 15N was abnormally high throughout the floodplain (1 to 5‰) indicating that older forests recycled salmon-N that accumulated during early succession. All plant species that occurred during the first several centuries of succession had N-rich foliage (mean C:N 12 to 22). We conclude that salmon fertilized otherwise N-poor early succession annually, and built ecosystem N-pools during early succession, thereby allowing nitrophilic plant species to proliferate. Thesis Kamchatka PQDT Open: Open Access Dissertations and Theses (ProQuest) Pacific Kol’ ENVELOPE(155.946,155.946,53.834,53.834) |
institution |
Open Polar |
collection |
PQDT Open: Open Access Dissertations and Theses (ProQuest) |
op_collection_id |
ftproquest |
language |
English |
topic |
Ecology |
spellingShingle |
Ecology Morris, Michael Roger The contribution of spawning Pacific-salmon to nitrogen fertility and vegetation nutrition during riparian primary succession on an expansive floodplain of a large river |
topic_facet |
Ecology |
description |
Floodplain vegetation communities are mosaics of succession stages caused by erosion/redeposition as river channels migrate throughout their floodplains. Typically, plants colonizing alluvial deposits are severely N-limited, but N accumulates during succession, and this process determines long term fertility. The Kol River (Kamchatka, RU), received large annual N-subsidies from salmon and we sought to determine how salmon-N contributed to fertility during succession. We constructed a vegetation chronosequence model and made N-fertility measurements within replicate succession stages before, during and after salmon runs. Natural abundance of 15N was used as a tracer of salmon-N. We found that new alluvial deposits were N-poor, containing <200 kg-N ha-1 (to 10cm). However, soil-N increased more than 10X within 30 years and soils were N-rich henceforth. Net N-mineralization on young alluvial bars only provided a small fraction of the colonizing forest’s N requirement, whereas soils in older forests provided abundant N. Negative correlation between foliar C:N and soil N during the first 20 years of succession indicated that the youngest succession stages were N-limited. The salmon run commenced in midsummer and caused river water N to increase 3X. Subsequent late season flooding deposited an average of 25 kg-N ha -1 as salmon carcasses onto young alluvial bars during 2006, but deposition rates were 10 to 30X higher on other years. The N-pulse created by decomposing salmon on young alluvial bars was brief because subsequent flooding flushed these coarse soils, but colonizing willows assimilated N rapidly during this time and high foliar δ15N (3 to 5‰) confirmed that salmon were a major N-source in early succession. Foliar δ 15N was abnormally high throughout the floodplain (1 to 5‰) indicating that older forests recycled salmon-N that accumulated during early succession. All plant species that occurred during the first several centuries of succession had N-rich foliage (mean C:N 12 to 22). We conclude that salmon fertilized otherwise N-poor early succession annually, and built ecosystem N-pools during early succession, thereby allowing nitrophilic plant species to proliferate. |
format |
Thesis |
author |
Morris, Michael Roger |
author_facet |
Morris, Michael Roger |
author_sort |
Morris, Michael Roger |
title |
The contribution of spawning Pacific-salmon to nitrogen fertility and vegetation nutrition during riparian primary succession on an expansive floodplain of a large river |
title_short |
The contribution of spawning Pacific-salmon to nitrogen fertility and vegetation nutrition during riparian primary succession on an expansive floodplain of a large river |
title_full |
The contribution of spawning Pacific-salmon to nitrogen fertility and vegetation nutrition during riparian primary succession on an expansive floodplain of a large river |
title_fullStr |
The contribution of spawning Pacific-salmon to nitrogen fertility and vegetation nutrition during riparian primary succession on an expansive floodplain of a large river |
title_full_unstemmed |
The contribution of spawning Pacific-salmon to nitrogen fertility and vegetation nutrition during riparian primary succession on an expansive floodplain of a large river |
title_sort |
contribution of spawning pacific-salmon to nitrogen fertility and vegetation nutrition during riparian primary succession on an expansive floodplain of a large river |
publisher |
University of Montana |
publishDate |
2008 |
url |
http://pqdtopen.proquest.com/#viewpdf?dispub=3310436 |
long_lat |
ENVELOPE(155.946,155.946,53.834,53.834) |
geographic |
Pacific Kol’ |
geographic_facet |
Pacific Kol’ |
genre |
Kamchatka |
genre_facet |
Kamchatka |
op_relation |
http://pqdtopen.proquest.com/#viewpdf?dispub=3310436 |
_version_ |
1766051752790982656 |