Plant species richness in ephemeral and perennial reaches of a dryland river

Juliet Stromberg, A. F. Hazelton, M. S. White

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

Ephemeral reaches are common along desert rivers but are less well studied than those with perennial stream flow. This study contrasted riparian plant species richness and composition (extant vegetation and soil seed bank) between stream reaches with different low-flow conditions (perennial vs. ephemeral flow) but similar flood patterns and similar watershed-derived species pools. Data were collected at Cienega Creek (Arizona, USA) over a 2 year period spanning drought conditions and wetter conditions. Consistent with expectations relating to water limitation effects on diversity, species richness in the riparian zone was lower at ephemeral-flow sites during a season with minimal precipitation and no overbank flooding; under these conditions, the more permanent water sources of the perennial-flow sites sustain the larger number of species. During seasons with greater precipitation and elevated stream flows, in contrast, species richness at ephemeral-flow sites increased to levels at or slightly above those of perennial-flow sites. For values pooled across two wet seasons of a calendar year, year-round richness was greater at the two ephemeral-flow sites (total of 92 vascular plant species) than at the two perennial-flow sites (68 species). This greater year-round richness was a combination of multiple factors: greater light, space, and bare ground, a diverse soil seed bank (with the seed banks equally species-rich among hydrologic types), and moderately abundant precipitation and flooding sufficient to stimulate establishment of opportunistic species (mainly annuals) during the bimodal wet seasons. These results indicate that long-term patterns of site water availability, by influencing woody plant cover, mediate the diversity response to episodic water pulses in dryland rivers. The results also have implications for riparian conservation efforts, which to date have focused primarily on perennial stream reaches: ephemeral reaches of spatially intermittent rivers harbor many riparian plant species, and warrant conservation efforts, as well.

Original languageEnglish (US)
Pages (from-to)663-677
Number of pages15
JournalBiodiversity and Conservation
Volume18
Issue number3
DOIs
StatePublished - Mar 2009

Fingerprint

arid lands
species richness
species diversity
rivers
river
seed bank
buried seeds
wet season
stream flow
streamflow
flooding
water
ephemeral stream
species pool
riparian zone
wet environmental conditions
woody plant
plant species
vascular plant
riparian areas

Keywords

  • Dryland river
  • Ephemeral stream
  • Plant community
  • Riparian ecosystem
  • Soil seed bank
  • Xeroriparian

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Ecology
  • Nature and Landscape Conservation

Cite this

Plant species richness in ephemeral and perennial reaches of a dryland river. / Stromberg, Juliet; Hazelton, A. F.; White, M. S.

In: Biodiversity and Conservation, Vol. 18, No. 3, 03.2009, p. 663-677.

Research output: Contribution to journalArticle

Stromberg, Juliet ; Hazelton, A. F. ; White, M. S. / Plant species richness in ephemeral and perennial reaches of a dryland river. In: Biodiversity and Conservation. 2009 ; Vol. 18, No. 3. pp. 663-677.
@article{2ebd20859fdb4d119816b0343fac2692,
title = "Plant species richness in ephemeral and perennial reaches of a dryland river",
abstract = "Ephemeral reaches are common along desert rivers but are less well studied than those with perennial stream flow. This study contrasted riparian plant species richness and composition (extant vegetation and soil seed bank) between stream reaches with different low-flow conditions (perennial vs. ephemeral flow) but similar flood patterns and similar watershed-derived species pools. Data were collected at Cienega Creek (Arizona, USA) over a 2 year period spanning drought conditions and wetter conditions. Consistent with expectations relating to water limitation effects on diversity, species richness in the riparian zone was lower at ephemeral-flow sites during a season with minimal precipitation and no overbank flooding; under these conditions, the more permanent water sources of the perennial-flow sites sustain the larger number of species. During seasons with greater precipitation and elevated stream flows, in contrast, species richness at ephemeral-flow sites increased to levels at or slightly above those of perennial-flow sites. For values pooled across two wet seasons of a calendar year, year-round richness was greater at the two ephemeral-flow sites (total of 92 vascular plant species) than at the two perennial-flow sites (68 species). This greater year-round richness was a combination of multiple factors: greater light, space, and bare ground, a diverse soil seed bank (with the seed banks equally species-rich among hydrologic types), and moderately abundant precipitation and flooding sufficient to stimulate establishment of opportunistic species (mainly annuals) during the bimodal wet seasons. These results indicate that long-term patterns of site water availability, by influencing woody plant cover, mediate the diversity response to episodic water pulses in dryland rivers. The results also have implications for riparian conservation efforts, which to date have focused primarily on perennial stream reaches: ephemeral reaches of spatially intermittent rivers harbor many riparian plant species, and warrant conservation efforts, as well.",
keywords = "Dryland river, Ephemeral stream, Plant community, Riparian ecosystem, Soil seed bank, Xeroriparian",
author = "Juliet Stromberg and Hazelton, {A. F.} and White, {M. S.}",
year = "2009",
month = "3",
doi = "10.1007/s10531-008-9532-z",
language = "English (US)",
volume = "18",
pages = "663--677",
journal = "Biodiversity and Conservation",
issn = "0960-3115",
publisher = "Springer Netherlands",
number = "3",

}

TY - JOUR

T1 - Plant species richness in ephemeral and perennial reaches of a dryland river

AU - Stromberg, Juliet

AU - Hazelton, A. F.

AU - White, M. S.

PY - 2009/3

Y1 - 2009/3

N2 - Ephemeral reaches are common along desert rivers but are less well studied than those with perennial stream flow. This study contrasted riparian plant species richness and composition (extant vegetation and soil seed bank) between stream reaches with different low-flow conditions (perennial vs. ephemeral flow) but similar flood patterns and similar watershed-derived species pools. Data were collected at Cienega Creek (Arizona, USA) over a 2 year period spanning drought conditions and wetter conditions. Consistent with expectations relating to water limitation effects on diversity, species richness in the riparian zone was lower at ephemeral-flow sites during a season with minimal precipitation and no overbank flooding; under these conditions, the more permanent water sources of the perennial-flow sites sustain the larger number of species. During seasons with greater precipitation and elevated stream flows, in contrast, species richness at ephemeral-flow sites increased to levels at or slightly above those of perennial-flow sites. For values pooled across two wet seasons of a calendar year, year-round richness was greater at the two ephemeral-flow sites (total of 92 vascular plant species) than at the two perennial-flow sites (68 species). This greater year-round richness was a combination of multiple factors: greater light, space, and bare ground, a diverse soil seed bank (with the seed banks equally species-rich among hydrologic types), and moderately abundant precipitation and flooding sufficient to stimulate establishment of opportunistic species (mainly annuals) during the bimodal wet seasons. These results indicate that long-term patterns of site water availability, by influencing woody plant cover, mediate the diversity response to episodic water pulses in dryland rivers. The results also have implications for riparian conservation efforts, which to date have focused primarily on perennial stream reaches: ephemeral reaches of spatially intermittent rivers harbor many riparian plant species, and warrant conservation efforts, as well.

AB - Ephemeral reaches are common along desert rivers but are less well studied than those with perennial stream flow. This study contrasted riparian plant species richness and composition (extant vegetation and soil seed bank) between stream reaches with different low-flow conditions (perennial vs. ephemeral flow) but similar flood patterns and similar watershed-derived species pools. Data were collected at Cienega Creek (Arizona, USA) over a 2 year period spanning drought conditions and wetter conditions. Consistent with expectations relating to water limitation effects on diversity, species richness in the riparian zone was lower at ephemeral-flow sites during a season with minimal precipitation and no overbank flooding; under these conditions, the more permanent water sources of the perennial-flow sites sustain the larger number of species. During seasons with greater precipitation and elevated stream flows, in contrast, species richness at ephemeral-flow sites increased to levels at or slightly above those of perennial-flow sites. For values pooled across two wet seasons of a calendar year, year-round richness was greater at the two ephemeral-flow sites (total of 92 vascular plant species) than at the two perennial-flow sites (68 species). This greater year-round richness was a combination of multiple factors: greater light, space, and bare ground, a diverse soil seed bank (with the seed banks equally species-rich among hydrologic types), and moderately abundant precipitation and flooding sufficient to stimulate establishment of opportunistic species (mainly annuals) during the bimodal wet seasons. These results indicate that long-term patterns of site water availability, by influencing woody plant cover, mediate the diversity response to episodic water pulses in dryland rivers. The results also have implications for riparian conservation efforts, which to date have focused primarily on perennial stream reaches: ephemeral reaches of spatially intermittent rivers harbor many riparian plant species, and warrant conservation efforts, as well.

KW - Dryland river

KW - Ephemeral stream

KW - Plant community

KW - Riparian ecosystem

KW - Soil seed bank

KW - Xeroriparian

UR - http://www.scopus.com/inward/record.url?scp=60449115820&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=60449115820&partnerID=8YFLogxK

U2 - 10.1007/s10531-008-9532-z

DO - 10.1007/s10531-008-9532-z

M3 - Article

VL - 18

SP - 663

EP - 677

JO - Biodiversity and Conservation

JF - Biodiversity and Conservation

SN - 0960-3115

IS - 3

ER -