Issues related to wetland delineation of a Texas, USA bottomland hardwood forest

Dewey, Janet C.; Schoenholtz, Stephen H.; Shepard, James P.; Messina, Michael

doi:10.1672/0277-5212(2006)26[410:irtwdo]2.0.co;2

Cited by 15 publications

(27 citation statements)

References 17 publications

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“…An advantage of dominance ratios is that they are generally easy to implement in the field. However, because they ignore non-dominant species and the relative abundance of dominant species, dominance ratios are often biased towards positive wetland determination, particularly at sites with many FAC species (Wakeley and Lichvar 1997;Dewey et al 2006). …”

Section: Methods For Determining Prevalencementioning

confidence: 99%

“…When quantitatively compared, hydrophytic vegetation decisions based on the prevalence index tend to agree more closely with hydric soil and hydrology indicators than decisions based on dominance ratios in several wetland types (Best et al 1990;Atkinson et al 1993;Davis et al 1996;. Dewey et al (2006) examined the results of several approaches for determining the prevalence of hydrophytes for delineation purposes in a bottomland hardwood forest in Texas. The authors evaluated outcomes for different variants of the dominance ratio method.…”

Section: Methods For Determining Prevalencementioning

confidence: 99%

“…In addition to the standard 50/20 rule, they evaluated their community data using the FAC neutral option whereby FAC species were removed from consideration, and a weighted FAC neutral test in which species with OBL and UPL indicator values were weighted twice that of FACW and FACU. The purpose was to reduce the effect of the ubiquity of FAC species on the determination (Dewey et al 2006). They also examined the effect of using a 10% threshold for determining whether individual species should be considered dominants (50/10 rule) to evaluate whether such a change significantly altered the outcome.…”

Section: Methods For Determining Prevalencementioning

confidence: 99%

“…may be able to persist even if hydrologic regimes change; in these cases, understory species may provide a more useful indicator of wetland status (Tiner 1999;USACE 2008g). Dewey et al (2006) suggested that, in their study area, the tree stratum may provide information on long-term wetland status, whereas the herbaceous layer may provide only short-term data, especially in sites with long, dry summers and where the vine stratum is dominated by annuals and perennials inhabiting dry microclimates created by other vegetation.…”

Section: Vegetation Stratification For Samplingmentioning

confidence: 99%

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Vegetation Sampling for Wetland Delineation: A Review and Synthesis of Methods and Sampling Issues

Gage¹,

Cooper²

2010

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This document reviews sampling issues and methods for characterizing vegetation, with an emphasis on delineating wetland boundaries in accordance with Section 404 of the Clean Water Act. Numerous vegetation sampling methods have been developed, but no single approach is optimal for all sampling objectives, vegetation types, and ecological settings. Methods vary in relative precision, accuracy, and efficiency, although selection of methods should also explicitly consider sampling objectives, resources, and data requirements. Key considerations include the choice of metric(s), selection of sampling units, and logistical issues such as time required for sample collection. Common metrics include frequency, cover, and biomass,

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Section: Methods For Determining Prevalencementioning

confidence: 99%

Section: Methods For Determining Prevalencementioning

confidence: 99%

Section: Methods For Determining Prevalencementioning

confidence: 99%

Section: Vegetation Stratification For Samplingmentioning

confidence: 99%

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Vegetation Sampling for Wetland Delineation: A Review and Synthesis of Methods and Sampling Issues

Gage¹,

Cooper²

2010

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“…The DR and the PI have been the subject of much research because they produce conflicting vegetation determinations 16%-54% of the time (Wakeley et al 1996;Wakeley and Lichvar 1997;Dewey et al 2006). The DR's role in these discrepancies has been well documented.…”

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confidence: 99%

Examining Discrepancies Among Three Methods Used to Make Hydrophytic Vegetation Determinations for Wetland Delineation Purposes

Lichvar¹,

Gillrich²

2014

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Three methods for making vegetation determinations-the Prevalence Index (PI), the Dominance Ratio (DR), and the Hydrophytic Cover Index (HCI)-were compared using national wetland delineation data. The PI and the DR produced significantly fewer hydrophytic determinations (69%, p < 0.01, and 76%, p = 0.04) than the HCI (80%). The three methods disagreed 16% of the time. The HCI produced hydrophytic determinations only in plots where hydrophyte (Facultative, Facultative Wetland, and Obligate species) cover was greater than 50% of the total cover and never produced hydrophytic determinations in plots where hydrophyte cover was 50% or less. The PI disagreed with the HCI 12% of the time, producing nonhydrophytic determinations in plots where hydrophyte cover was greater than 50%. The DR disagreed with the HCI 9% of the time. Disagreements included nonhydrophytic determinations in plots where hydrophyte cover was greater than 50%, hydrophytic determinations in plots where hydrophyte cover was 50% or less, and a nonhydrophytic bias in plots dominated by even numbers of plant species. These results demonstrate that HCI determinations are more accurate and consistent than those of the PI and the DR. The HCI method is recommended for making vegetation determinations during wetland delineations in future revisions of the Corps delineation manual and its supplements.

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Wetland tree transpiration modified by river‐floodplain connectivity

et al. 2016

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Hydrologic connectivity provisions water and nutrient subsidies to floodplain wetlands and may be particularly important in floodplains with seasonal water deficits through its effects on soil moisture. In this study, we measured sapflow in 26 trees of two dominant floodplain forest species (Celtis laevigata and Quercus lyrata) at two hydrologically distinct sites in the lower White River floodplain in Arkansas, USA. Our objective was to investigate how connectivity-driven water table variations affected water use, an indicator of tree function. Meteorological variables (photosynthetically active radiation and vapor pressure deficit) were the dominant controls over water use at both sites; however, water table variations explained some site differences. At the wetter site, highest sapflow rates were during a late-season overbank flooding event, and no flood stress was apparent. At the drier site, sapflow decreased as the water table receded. The late-season flood pulse that resulted in flooding at the wetter site did not affect the water table at the drier site; accordingly, higher water use was not observed at the drier site. The species generally associated with wetter conditions (Q. lyrata) was more positively responsive to the flood pulse. Flood water subsidy lengthened the effective growing season, demonstrating ecological implications of hydrologic connectivity for alleviating water deficits that otherwise reduce function in this humid floodplain wetland.

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Issues related to wetland delineation of a Texas, USA bottomland hardwood forest

Cited by 15 publications

References 17 publications

Vegetation Sampling for Wetland Delineation: A Review and Synthesis of Methods and Sampling Issues

Vegetation Sampling for Wetland Delineation: A Review and Synthesis of Methods and Sampling Issues

Examining Discrepancies Among Three Methods Used to Make Hydrophytic Vegetation Determinations for Wetland Delineation Purposes

Wetland tree transpiration modified by river‐floodplain connectivity

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