Effects of herbicide treatments on biotic components in regenerating northern forests

Abstract

We reviewed literature, primarily since 1990, that documents effects of herbicide treatments on major biotic components in northern forested ecosystems. Vegetation changes are responsible for changes in all other biotic components. Non-conifer vegetation is commonly reduced for two to five years following broadcast herbicide treatments. Fungal components, however, seem relatively unaffected. Short-term vegetation reductions in cover, density, and related biomass, if they occur, are species and/or vegetation group specific; longer-term changes are linked to conifer stocking, site quality, and the ability of conifers to dominate treated sites. Herbicide treatments do not reduce, and may increase, stand-and landscape-level plant species richness. Those treatments seldom produce monocultures when used by foresters for boreal or boreal mixedwood management. The active ingredients in the herbicide products used in forestry in northern ecosystems have no direct effect on the general health (survival, growth, reproduction) of animals in treated areas. Specific, stand-level forest management practices, particularly effects of site preparation and conifer release, must be examined in relation to the landscape mosaic and the desired future forest conditions. At broad scales, across boreal and boreal mixedwood ecosystems, conifers have been consistently replaced by hardwoods since Europeans began harvesting timber from those ecosystems. Herbicides provide a safe, effective tool for restoring conifers in previously conifer-dominated ecosystems. Forest scientists presently have a reasonable understanding of effects of a variety of herbicide treatments on conifer growth and a variety of environmental components. However, they need to continually update that understanding relative to treatments (replicates, chemicals, combinations, or timing) that may be used in the future.Key words: amphibians, conifer release, deer, disturbance, environment, glyphosate, herbicides, invertebrates, landscape, moose, reptiles, site preparation, small mammals, songbirds, snowshoe hare, triclopyr, vegetation Nous avons révisé la littérature, principalement depuis 1990, qui documente les effets des traitements phytocides sur les principaux éléments biotiques dans les écosystèmes forestiers nordiques. Les modifications apportées à la végétation sont responsables des changements survenus chez tous les autres éléments biotiques. La végétation non-résineuse est habituellement réduite de deux à cinq ans suivant les traitements d'épandage généralisé de phytocides. Les composantes fongiques, cependant, ne semblent relativement pas affectées. Les réductions à court terme de la végétation au niveau du couvert, de la densité et de la biomasse impliquée, si tel est le cas, touchent spécifiquement certaines espèces ou groupe de plantes; les changements à long terme sont reliés au nombre de semis de résineux, la qualité de la station et la capacité des résineux à dominer dans les sites traités. Les traitements phytocides ne réduisent pas, et pourraient accroîtr...

What are the Environmental Consequences of Using Silviculturally Effective Forest Vegetation Management Treatments?

“…In general, deer seem unaffected by herbicide treatments while moose (Alces alces) consistently reduce their use of treated areas during the first three to five years after treatment (Lautenschlager and Sullivan 2002). This behaviour appears to be directly linked to the availability of browse and habitat.…”

“…Vegetation responses to herbicide treatment can result in temporary increases in some small mammals (e.g., least chipmunk) and decreases in others (e.g., eastern chipmunk) (see Lautenschlager and Sullivan 2002). Depressed populations, however, tend to recover after three to four years (Fortier and Messier 2006;McLaren et al 2011, this issue).…”

“…87, No. 2 -Th e For esTr y ch r oNicl e reviews conducted by Lautenschlager and Sullivan (2002), Guiseppe et al (2006), andNCASI (2009), show no direct toxicity from herbicides, such as glyphosate, when applied at normal operational levels (i.e., according to label directions) and no evidence of bioaccumulation or bioconcentration has been reported for birds. For the most part, these same reviews suggest that any deleterious effects from herbicides would be indirect effects on forage or nesting habitat.…”

“…Depending on the species, herbicides can positively or negatively affect songbirds in the short-and mid-term (Lautenschlager and Sullivan 2002), due to changes in habitat rather than any direct harm to the bird itself (Guiseppe et al 2006, NCASI 2009). .…”

“…Bell et al (1998) summarized the effects of silvicultural and harvesting systems and physical, thermal, cultural, and chemical FVM treatments in a series of technical notes. Lautenschlager and Sullivan (2002) summarized the effects of herbicide treatments on biotic components in regenerating northern forests. Fisher and Wilkinson (2005) reviewed the effects of fire and harvesting on various groups of wildlife.…”