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 δ15N 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 nitrophillic plant species to proliferate.
","abstract_html":"<p>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. </p> <p>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. </p> <p>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. </p> <p>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 δ15N was abnormally high throughout the floodplain (1 to 5) indicating that older forests recycled salmon-N that accumulated during early succession. </p> <p>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 nitrophillic plant species to proliferate.</p>","abstract_has_math":false,"creators":["Morris, Michael Roger"],"institution":"University of Montana","degree_name":"Doctor of Philosophy (PhD)","degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2008,"date_issued":"2008-01-01T08:00:00Z","date_published":"2008-01-01T08:00:00Z","updated_at":"2026-07-24T03:14:06Z","subjects":["15N stable isotope","floodplain primary succession","marine derived nutrients","Pacific-salmon","Kol River","nitrogen"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://scholarworks.umt.edu/etd/972","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Morris, Michael Roger"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:publisher","label":"Institution","values":["University of Montana"]},{"key":"dc:type","label":"Dc Type","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Doctor of Philosophy (PhD)"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["15N stable isotope","floodplain primary succession","marine derived nutrients","Pacific-salmon","Kol River","nitrogen"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://scholarworks.umt.edu/etd/972"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["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 δ15N 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 nitrophillic plant species to proliferate.
"]},{"key":"dc:title","label":"Title","values":["The Contribution of Spawning Pacific-salmon to Nitrogen Fertility and Vegetation Nutrition during Riparian Primary Succession on an Expansive Floodplain of a Large River"]}]}],"canonical_facts":{"dc:creator":["Morris, Michael Roger"],"dc:description.abstract":["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 δ15N 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 nitrophillic plant species to proliferate.
"],"dc:identifier":["https://scholarworks.umt.edu/etd/972"],"dc:publisher":["University of Montana"],"dc:subject":["15N stable isotope","floodplain primary succession","marine derived nutrients","Pacific-salmon","Kol River","nitrogen"],"dc: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"],"dc:type":["Dissertation"],"thesis:degree_name":["Doctor of Philosophy (PhD)"]},"updated_at":"2026-07-24T03:14:06Z"}