Hexazinone dissipation in forest ecosystems and impacts on aquatic communities

Michael, Jerry L.; Webber, E. Cliff; Bayne, David R.; Fischer, Joseph B.; Gibbs, Hilliard; Seesock, Wendy C.

doi:10.1139/x99-028

Cited by 21 publications

(9 citation statements)

References 43 publications

(76 reference statements)

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“…Although herbicide application appeared to be the most effective long-term strategy for moving avian assemblages toward that of reference sites, further research is warranted. For example, the active ingredient of the herbicide in this study, hexazinone, can reach surrounding bodies of water (Neary et al 1983); hexazinone is generally considered safe for wildlife (Michael et al 1999) but limited research has been conducted pertaining to some groups (Berrill et al 1994, Bridges andSemlitsch 2000). In addition, application of herbicides was relatively ineffective at restoring reptile assemblages at the same site (Steen et al 2013).…”

Section: Synthesis and Management Implicationsmentioning

confidence: 87%

Bird assemblage response to restoration of fire‐suppressed longleaf pine sandhills

Steen¹,

Conner²,

Smith³

et al. 2013

Ecological Applications

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The ecological restoration of fire-suppressed habitats may require a multifaceted approach. Removal of hardwood trees together with reintroduction of fire has been suggested as a method of restoring fire-suppressed longleaf pine (Pinus palustris) forests; however, this strategy, although widespread, has not been evaluated on large spatial and temporal scales. We used a landscape-scale experimental design to examine how bird assemblages in fire-suppressed longleaf pine sandhills responded to fire alone or fire following mechanical removal or herbicide application to reduce hardwood levels. Individual treatments were compared to fire-suppressed controls and reference sites. After initial treatment, all sites were managed with prescribed fire, on an approximately two- to three-year interval, for over a decade. Nonmetric multidimensional scaling ordinations suggested that avian assemblages on sites that experienced any form of hardwood removal differed from assemblages on both fire-suppressed sites and reference sites 3-4 years after treatment (i.e., early posttreatment). After >10 years of prescribed burning on all sites (i.e., late posttreatment), only assemblages at sites treated with herbicide were indistinguishable from assemblages at reference sites. By the end of the study, individual species that were once indicators of reference sites no longer contributed to making reference sites unique. Occupancy modeling of these indicator species also demonstrated increasing similarity across treatments over time. Overall, although we documented long-term and variable assemblage-level change, our results indicate occupancy for birds considered longleaf pine specialists was similar at treatment and reference sites after over a decade of prescribed burning, regardless of initial method of hardwood removal. In other words, based on the response of species highly associated with the habitat, we found no justification for the added cost and effort of fire surrogates; fire alone was sufficient to restore these species.

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Section: Synthesis and Management Implicationsmentioning

confidence: 87%

Bird assemblage response to restoration of fire‐suppressed longleaf pine sandhills

Steen¹,

Conner²,

Smith³

et al. 2013

Ecological Applications

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“…Degradation of hexazinone in soils and sediments is mainly due to microbial metabolism and photodegradation (U.S. EPA 1994). The reported half-lives for hexazinone in soil in field studies range from 24 days-1 year (Michael et al 1999).…”

Section: Hexazinone (Velpar ® )mentioning

confidence: 99%

Toxicity, transport, and fate of forest herbicides

Tatum¹

2004

Wildlife Society Bulletin

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Public opposition to use of herbicides in forests typically centers around concerns over potential toxicity to wildlife. Characterization of the risk of silvicultural herbicides to wildlife requires an understanding of herbicide toxicity and environmental fate and transport. The fate and chemistry of herbicides and adjuvants within environmental media determine how and which organisms may be exposed and duration of those exposures. The nature of the toxicity of herbicides, adjuvants, and their decomposition products, and levels at which those toxic responses may be observed, determine which organisms or life stages may be most susceptible to any toxic effects and which exposure concentrations and durations can be considered safe. In general, herbicides most commonly used for vegetation management in forestry (glyphosate, triclopyr, imazapyr, sulfometuron, metsulfuron methyl, hexazinone) degrade quickly once they enter the environment and thus are neither persistent nor bioaccumulative. Because modern herbicides have been designed to target biochemical processes unique to plants, they exhibit a low level of direct toxicity to animals. When used according to label instructions, modern silvicultural herbicides pose little risk to wildlife.

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“…2) . Michael et al (1999) reported water samples collected from watersheds aerially sprayed with hexazinone had peak herbicide concentrations at peak discharge, probably due to overland flow conditions. Pelleted hexazinone applications resulted in peak herbicide concentrations several hours after peak discharge.…”

Section: Resultsmentioning

confidence: 99%

“…Therefore, movement off site was minimal or nonexistent for these two watersheds. Previous reports on picloram (Michael et al, 1989) and hexazinone (Michael et al, 1999) have demonstrated significant and linear dilution effects related to watershed size at distances of 500 to 1600 m downstream. It may be that the flat‐topography, braided‐stream condition close to the edge of the treated area and pretreatment disking and bedding are partially responsible for the near lack of offsite movement observed in this study.…”

Section: Resultsmentioning

confidence: 99%

Environmental Fate and Impacts of Sulfometuron on Watersheds in the Southern United States

Michael¹

2003

J of Env Quality

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Dissipation of sulfometuron (SM), methyl 2-[[[[(4,6-dimethyl-2-pyrimidinyl)amino]carbonyl]amino]sulfonyl] benzoate, in streamflow, sediment, plant tissue, litter, and soil following operational forestry applications at the target rate of 0.42 kg a.i. ha(-1) was monitored. Streamflow samples were collected at a weir on the perimeter and 30, 60, and 150 m downstream from the perimeter of the application site. Sulfometuron was detected in streamflow at low levels up to 29 days after treatment (DAT) on the watershed treated with the 75% dispersible granule formulation (Oust; DuPont Chemical Company, Wilmington, DE) and less than 53 DAT on the watershed treated with the experimental formulation (1% pellet). Twenty-four-hour average SM concentration in water ranged from not detected to a maximum of 49.3 microg L(-1). Sulfometuron was not detected at quantifiable levels (1 microg L(-1)) 150 m downstream. Stream sediment, vegetation, litter, and soil were sampled periodically up to 180 DAT. All samples were analyzed for SM by high performance liquid chromatography. Sulfometuron dissipated from these watersheds with half-lives that ranged from 4 d in plant tissues to 33 d in soil. Acidic soil solution on these treated watersheds contributed to their rapid dissipation. Environmental impacts are discussed for these watersheds in the context of available toxicological data.

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Hexazinone dissipation in forest ecosystems and impacts on aquatic communities

Cited by 21 publications

References 43 publications

Bird assemblage response to restoration of fire‐suppressed longleaf pine sandhills

Bird assemblage response to restoration of fire‐suppressed longleaf pine sandhills

Toxicity, transport, and fate of forest herbicides

Environmental Fate and Impacts of Sulfometuron on Watersheds in the Southern United States

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