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Flood Disturbance (flood + disturbance)

Distribution by Scientific Domains
Life Sciences100%

Selected Abstracts

Flood disturbance, algal productivity, and interannual variation in food chain length

OIKOS, Issue 1 2000
Jane C. Marks
The length of a river food chain changed from year to year, shifting with the hydrologic regime. During drought years, grazers suppressed algae across a nutrient gradient, while predators were functionally unimportant. Following flood disturbance, predators suppressed grazers, releasing algae. These results suggest that hydrologic regime, rather than productivity, determines the functional length of this river food chain. Within years, algae and grazer biomass responded to an experimental productivity gradient in patterns predicted by simple trophic models that assume efficient energy transfer. Understanding differences among species within trophic levels, however, was crucial in delineating the controlling interactions. [source]

Differences in seed mass between hydric and xeric plants influence seed bank dynamics in a dryland riparian ecosystem

FUNCTIONAL ECOLOGY, Issue 2 2008
J. C. Stromberg
Summary 1Dryland riparian zones have steep spatial gradients of soil moisture and flood disturbance, and the component hydrogeomorphic surfaces support hydric to xeric plant species. These systems undergo extremes of flood and drought, a dynamic that may select for persistent soil seed banks. We asked if reliance on this strategy differed among plants in three moisture groups (hydric, mesic and xeric), and if patterns were related to diaspore traits. 2We assessed the composition of soil and litter seed banks (emergence method) and extant vegetation along a riparian hydrogradient, and measured seed persistence (using an indirect method) and diaspore mass and shape variance of the component species. 3Hydroriparian species had smaller diaspores than xeroriparian species, corresponding to differences in selective pressures on seedlings in their respective habitats, but the two groups formed persistent seed banks at approximately equal percentages. Persistent seeds were smaller than transient seeds, but within the persistent seed group there was separation between the smaller-diaspored hydrophytes and larger-diaspored xerophytes. 4Distribution patterns of extant vegetation, in concert with diaspore trait differences among moisture-affinity groups, gave rise to divergent spatial patterns of diaspores within the soil: hydroriparian diaspores were abundant not only along wet channel bars but also in deep soils under floodplain forests and shrublands, presumably owing to dispersal by flood waters. Xeroriparian diaspores were largely restricted to the litter and upper soil layers of their drier, higher, floodplain habitats. With increasing depth in the soil of floodplain forests and shrublands, viable diaspores became smaller and rounder, and plant composition shifted from xeroriparian to hydroriparian species. 5The wide distribution of hydroriparian diaspores in floodplain soils influences disturbance dynamics, increasing the probability that ephemeral wetland communities will develop wherever suitable conditions are stochastically created by floods. Persistent seed banks also allow many xeric annuals to be maintained in dryland riparian zones throughout extended drought, similar to processes that occur in desert uplands. [source]

Flood disturbance, algal productivity, and interannual variation in food chain length

OIKOS, Issue 1 2000
Jane C. Marks
The length of a river food chain changed from year to year, shifting with the hydrologic regime. During drought years, grazers suppressed algae across a nutrient gradient, while predators were functionally unimportant. Following flood disturbance, predators suppressed grazers, releasing algae. These results suggest that hydrologic regime, rather than productivity, determines the functional length of this river food chain. Within years, algae and grazer biomass responded to an experimental productivity gradient in patterns predicted by simple trophic models that assume efficient energy transfer. Understanding differences among species within trophic levels, however, was crucial in delineating the controlling interactions. [source]

Influence of Inorganic Substrata Size, Leaf Litter and Woody Debris Removal on Benthic Invertebrates Resistance to Floods in Two Contrasting Headwater Streams

INTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 1 2005
J. Bosco Imbert
Abstract We studied the influence of inorganic substrata size, leaf litter and woody debris removal on the resistance of benthic invertebrates to floods in two contrasting forested headwater streams of the Agüera basin (northern Spain): Cuchillo stream (stream bed dominated by cobbles and pebbles) and Salderrey stream (stream bed dominated by bedrock and boulders). Generally, floods had a greater effect on benthic invertebrates resistance in the Salderrey stream, apparently due to the high presence of loose substrata overlaying bedrock and the higher scouring of sediment in this stream. Unlike Salderrey stream total number of individuals of Simuliidae, Echinogammarus tarragonensis and Protonemura spp. in riffles greatly increased at the reach scale in the Cuchillo stream after two floods, suggesting that Cuchillo was more retentive than Salderrey. A positive relationship between substrata size and invertebrate resistance to floods was found in the Cuchillo stream but not in the Salderrey stream. It appears that the flood disturbances in the Salderrey stream were too strong to find an increase in resistance as substrata size increased. Invertebrate resistance on leaf litter and resistance predictability were also higher in the Cuchillo stream; the former result suggests that retention of leaf packs was greater in the Cuchillo stream. The lack of a statistically significant effect of woody debris removal may imply that the composition and stability of inorganic substrata have more influence on invertebrate resistance to floods than woody debris at the reach scale in these headwater streams dominated by relatively stable substrata. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]