Nutrient vectors and riparian processing: A review with special reference to African semiarid savanna ecosystems

S. M. Jacobs, J. S. Bechtold, H. C. Biggs, Nancy Grimm, S. Lorentz, M. E. McClain, R. J. Naiman, S. S. Perakis, G. Pinay, M. C. Scholes

Research output: Contribution to journalArticle

49 Citations (Scopus)

Abstract

This review article describes vectors for nitrogen and phosphorus delivery to riparian zones in semiarid African savannas, the processing of nutrients in the riparian zone and the effect of disturbance on these processes. Semiarid savannas exhibit sharp seasonality, complex hillslope hydrology and high spatial heterogeneity, all of which ultimately impact nutrient fluxes between riparian, upland and aquatic environments. Our review shows that strong environmental drivers such as fire and herbivory enhance nitrogen, phosphorus and sediment transport to lower slope positions by shaping vegetative patterns. These vectors differ significantly from other arid and semiarid ecosystems, and from mesic ecosystems where the impact of fire and herbivory are less pronounced and less predictable. Also unique is the presence of sodic soils in certain hillslopes, which substantially alters hydrological flowpaths and may act as a trap where nitrogen is immobilized while sediment and phosphorus transport is enhanced. Nutrients and sediments are also deposited in the riparian zone during seasonal, intermittent floods while, during the dry season, subsurface movement of water from the stream into riparian soils and vegetation further enrich riparian zones with nutrients. As is found in mesic ecosystems, nutrients are immobilized in semiarid riparian corridors through microbial and plant uptake, whereas dissimilatory processes such as denitrification may be important where labile nitrogen and carbon are in adequate supply and physical conditions are suitable-such as in seeps, wallows created by animals, ephemeral wetlands and stream edges. Interaction between temporal hydrologic connectivity and spatial heterogeneity are disrupted by disturbances such as large floods and extended droughts, which may convert certain riparian patches from sinks to sources for nitrogen and phosphorus. In the face of increasing anthropogenic pressure, the scientific challenges are to provide a basic understanding of riparian biogeochemistry in semiarid African savannas to adequately address the temporal and spatial impact of disturbances, and to apply this knowledge to better regional land and water management. An integrated, multidisciplinary approach applied in protected as well as human-disturbed ecosystems in southern Africa is essential for underpinning a strong environmental basis for sustainable human-related expansion.

Original languageEnglish (US)
Pages (from-to)1231-1249
Number of pages19
JournalEcosystems
Volume10
Issue number8
DOIs
StatePublished - Dec 2007

Fingerprint

riparian areas
savanna
Ecosystems
Nutrients
riparian zone
savannas
Nitrogen
Phosphorus
ecosystems
nutrient
ecosystem
nitrogen
nutrients
phosphorus
Processing
hillslope
disturbance
herbivory
Sediments
Fires

Keywords

  • Fluvial disturbance
  • Nitrogen
  • Phosphorus
  • Riparian biogeochemistry
  • Semiarid landscapes
  • South Africa

ASJC Scopus subject areas

  • Ecology

Cite this

Jacobs, S. M., Bechtold, J. S., Biggs, H. C., Grimm, N., Lorentz, S., McClain, M. E., ... Scholes, M. C. (2007). Nutrient vectors and riparian processing: A review with special reference to African semiarid savanna ecosystems. Ecosystems, 10(8), 1231-1249. https://doi.org/10.1007/s10021-007-9092-1

Nutrient vectors and riparian processing : A review with special reference to African semiarid savanna ecosystems. / Jacobs, S. M.; Bechtold, J. S.; Biggs, H. C.; Grimm, Nancy; Lorentz, S.; McClain, M. E.; Naiman, R. J.; Perakis, S. S.; Pinay, G.; Scholes, M. C.

In: Ecosystems, Vol. 10, No. 8, 12.2007, p. 1231-1249.

Research output: Contribution to journalArticle

Jacobs, SM, Bechtold, JS, Biggs, HC, Grimm, N, Lorentz, S, McClain, ME, Naiman, RJ, Perakis, SS, Pinay, G & Scholes, MC 2007, 'Nutrient vectors and riparian processing: A review with special reference to African semiarid savanna ecosystems', Ecosystems, vol. 10, no. 8, pp. 1231-1249. https://doi.org/10.1007/s10021-007-9092-1
Jacobs, S. M. ; Bechtold, J. S. ; Biggs, H. C. ; Grimm, Nancy ; Lorentz, S. ; McClain, M. E. ; Naiman, R. J. ; Perakis, S. S. ; Pinay, G. ; Scholes, M. C. / Nutrient vectors and riparian processing : A review with special reference to African semiarid savanna ecosystems. In: Ecosystems. 2007 ; Vol. 10, No. 8. pp. 1231-1249.
@article{dce08c8f9a7a4adcb3e0f253e3cb4380,
title = "Nutrient vectors and riparian processing: A review with special reference to African semiarid savanna ecosystems",
abstract = "This review article describes vectors for nitrogen and phosphorus delivery to riparian zones in semiarid African savannas, the processing of nutrients in the riparian zone and the effect of disturbance on these processes. Semiarid savannas exhibit sharp seasonality, complex hillslope hydrology and high spatial heterogeneity, all of which ultimately impact nutrient fluxes between riparian, upland and aquatic environments. Our review shows that strong environmental drivers such as fire and herbivory enhance nitrogen, phosphorus and sediment transport to lower slope positions by shaping vegetative patterns. These vectors differ significantly from other arid and semiarid ecosystems, and from mesic ecosystems where the impact of fire and herbivory are less pronounced and less predictable. Also unique is the presence of sodic soils in certain hillslopes, which substantially alters hydrological flowpaths and may act as a trap where nitrogen is immobilized while sediment and phosphorus transport is enhanced. Nutrients and sediments are also deposited in the riparian zone during seasonal, intermittent floods while, during the dry season, subsurface movement of water from the stream into riparian soils and vegetation further enrich riparian zones with nutrients. As is found in mesic ecosystems, nutrients are immobilized in semiarid riparian corridors through microbial and plant uptake, whereas dissimilatory processes such as denitrification may be important where labile nitrogen and carbon are in adequate supply and physical conditions are suitable-such as in seeps, wallows created by animals, ephemeral wetlands and stream edges. Interaction between temporal hydrologic connectivity and spatial heterogeneity are disrupted by disturbances such as large floods and extended droughts, which may convert certain riparian patches from sinks to sources for nitrogen and phosphorus. In the face of increasing anthropogenic pressure, the scientific challenges are to provide a basic understanding of riparian biogeochemistry in semiarid African savannas to adequately address the temporal and spatial impact of disturbances, and to apply this knowledge to better regional land and water management. An integrated, multidisciplinary approach applied in protected as well as human-disturbed ecosystems in southern Africa is essential for underpinning a strong environmental basis for sustainable human-related expansion.",
keywords = "Fluvial disturbance, Nitrogen, Phosphorus, Riparian biogeochemistry, Semiarid landscapes, South Africa",
author = "Jacobs, {S. M.} and Bechtold, {J. S.} and Biggs, {H. C.} and Nancy Grimm and S. Lorentz and McClain, {M. E.} and Naiman, {R. J.} and Perakis, {S. S.} and G. Pinay and Scholes, {M. C.}",
year = "2007",
month = "12",
doi = "10.1007/s10021-007-9092-1",
language = "English (US)",
volume = "10",
pages = "1231--1249",
journal = "Ecosystems",
issn = "1432-9840",
publisher = "Springer New York",
number = "8",

}

TY - JOUR

T1 - Nutrient vectors and riparian processing

T2 - A review with special reference to African semiarid savanna ecosystems

AU - Jacobs, S. M.

AU - Bechtold, J. S.

AU - Biggs, H. C.

AU - Grimm, Nancy

AU - Lorentz, S.

AU - McClain, M. E.

AU - Naiman, R. J.

AU - Perakis, S. S.

AU - Pinay, G.

AU - Scholes, M. C.

PY - 2007/12

Y1 - 2007/12

N2 - This review article describes vectors for nitrogen and phosphorus delivery to riparian zones in semiarid African savannas, the processing of nutrients in the riparian zone and the effect of disturbance on these processes. Semiarid savannas exhibit sharp seasonality, complex hillslope hydrology and high spatial heterogeneity, all of which ultimately impact nutrient fluxes between riparian, upland and aquatic environments. Our review shows that strong environmental drivers such as fire and herbivory enhance nitrogen, phosphorus and sediment transport to lower slope positions by shaping vegetative patterns. These vectors differ significantly from other arid and semiarid ecosystems, and from mesic ecosystems where the impact of fire and herbivory are less pronounced and less predictable. Also unique is the presence of sodic soils in certain hillslopes, which substantially alters hydrological flowpaths and may act as a trap where nitrogen is immobilized while sediment and phosphorus transport is enhanced. Nutrients and sediments are also deposited in the riparian zone during seasonal, intermittent floods while, during the dry season, subsurface movement of water from the stream into riparian soils and vegetation further enrich riparian zones with nutrients. As is found in mesic ecosystems, nutrients are immobilized in semiarid riparian corridors through microbial and plant uptake, whereas dissimilatory processes such as denitrification may be important where labile nitrogen and carbon are in adequate supply and physical conditions are suitable-such as in seeps, wallows created by animals, ephemeral wetlands and stream edges. Interaction between temporal hydrologic connectivity and spatial heterogeneity are disrupted by disturbances such as large floods and extended droughts, which may convert certain riparian patches from sinks to sources for nitrogen and phosphorus. In the face of increasing anthropogenic pressure, the scientific challenges are to provide a basic understanding of riparian biogeochemistry in semiarid African savannas to adequately address the temporal and spatial impact of disturbances, and to apply this knowledge to better regional land and water management. An integrated, multidisciplinary approach applied in protected as well as human-disturbed ecosystems in southern Africa is essential for underpinning a strong environmental basis for sustainable human-related expansion.

AB - This review article describes vectors for nitrogen and phosphorus delivery to riparian zones in semiarid African savannas, the processing of nutrients in the riparian zone and the effect of disturbance on these processes. Semiarid savannas exhibit sharp seasonality, complex hillslope hydrology and high spatial heterogeneity, all of which ultimately impact nutrient fluxes between riparian, upland and aquatic environments. Our review shows that strong environmental drivers such as fire and herbivory enhance nitrogen, phosphorus and sediment transport to lower slope positions by shaping vegetative patterns. These vectors differ significantly from other arid and semiarid ecosystems, and from mesic ecosystems where the impact of fire and herbivory are less pronounced and less predictable. Also unique is the presence of sodic soils in certain hillslopes, which substantially alters hydrological flowpaths and may act as a trap where nitrogen is immobilized while sediment and phosphorus transport is enhanced. Nutrients and sediments are also deposited in the riparian zone during seasonal, intermittent floods while, during the dry season, subsurface movement of water from the stream into riparian soils and vegetation further enrich riparian zones with nutrients. As is found in mesic ecosystems, nutrients are immobilized in semiarid riparian corridors through microbial and plant uptake, whereas dissimilatory processes such as denitrification may be important where labile nitrogen and carbon are in adequate supply and physical conditions are suitable-such as in seeps, wallows created by animals, ephemeral wetlands and stream edges. Interaction between temporal hydrologic connectivity and spatial heterogeneity are disrupted by disturbances such as large floods and extended droughts, which may convert certain riparian patches from sinks to sources for nitrogen and phosphorus. In the face of increasing anthropogenic pressure, the scientific challenges are to provide a basic understanding of riparian biogeochemistry in semiarid African savannas to adequately address the temporal and spatial impact of disturbances, and to apply this knowledge to better regional land and water management. An integrated, multidisciplinary approach applied in protected as well as human-disturbed ecosystems in southern Africa is essential for underpinning a strong environmental basis for sustainable human-related expansion.

KW - Fluvial disturbance

KW - Nitrogen

KW - Phosphorus

KW - Riparian biogeochemistry

KW - Semiarid landscapes

KW - South Africa

UR - http://www.scopus.com/inward/record.url?scp=37749038535&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=37749038535&partnerID=8YFLogxK

U2 - 10.1007/s10021-007-9092-1

DO - 10.1007/s10021-007-9092-1

M3 - Article

AN - SCOPUS:37749038535

VL - 10

SP - 1231

EP - 1249

JO - Ecosystems

JF - Ecosystems

SN - 1432-9840

IS - 8

ER -