In New Zealand, glyphosate is one of the most important herbicides used for the management of competing vegetation in forests prior to commercial tree planting, with very limited use post-planting i.e., it is typically applied once in a rotation of 25 to 30 years [42] (Table 1). Glyphosate is applied, almost exclusively, aerially in late summer and early autumn, in combination with metsulfuron methyl, at respectively ~3.5 kg a.i. ha⁻¹ and ~0.12 kg a.i. ha⁻¹ in 150 L water. The application is made after harvesting shortly before the site is replanted when a high degree of organic debris, or logging slash, is present [43]. A review by Rolando et al. [42] indicated that commercial forests in New Zealand use an estimated 175 tonnes of glyphosate per annum for management of competitive vegetation during site preparation (Table 1). Based on these data, glyphosate ranks as the third highest used herbicide across the planted forest industry in New Zealand. A survey in 2002/2003 indicated that 42% of total glyphosate use in New Zealand is associated with management of vegetation in planted Pinus radiata forests with the remainder used in the horticultural and pastoral farming systems [37].

In Australia, glyphosate is principally used in pre-plant vegetation control operations in both softwood and hardwood planted forests, with limited use post-planting (Table 1). The herbicide is mainly broadcast via ground based machine or by helicopter, with use of hand-spraying limited to buffers, right-of-ways and sensitive boundaries [31]. The maximum label rate is 3.36 kg a.i. ha⁻¹, with use rates generally not exceeding 2.88 kg a.i. ha⁻¹ (Gillie personal communication [44]). While no published data on the total amount of glyphosate used in planted forests in Australia was available it was estimated that use of glyphosate in Australian planted forests was in the range of ~200 to 250 tonnes annum⁻¹ (Table 1).

A variety of hardwoods and softwoods are grown in South Africa for production of a range of end-products (saw-timber, pulpwood, poles and mining timber). Establishment, or regeneration, of planted forests may be through re-planting (all genera), or coppicing (eucalypts). The variation in site productivity, regeneration and management regimes means a diversity of vegetation management practices are used [45]. Competing vegetation is controlled through a combination of physical control (manual hoeing or slashing) and application of herbicides. The predominant herbicide used is glyphosate (Table 1), where in South Africa, forestry accounts for 4% of the total glyphosate used [46].

Glyphosate applied as a pre-plant spray may be sprayed aerially (seldom), or manually using knapsack sprayers (more common) at 1.76 to 2.32 kg a.i. ha⁻¹ [33]. All post-planting applications of glyphosate are via knapsack sprayers, either as a broadcast or directed/spot application depending on the size of the trees [47,48]. Between planting and canopy closure (<2 years), a eucalypt pulpwood stand will typically receive one broadcast application of glyphosate (with cones for tree protection), followed by two to three directed applications [47]. The duration of vegetation control in pine compartments is typically longer due to slower initial tree growth, requiring an additional two directed spot sprays in years three to five [48]. In South Africa, glyphosate is also used to manage secondary coppice regrowth in coppiced eucalypt stands where it is applied as a directed foliar spray at 1.2% (441 g a.i. L⁻¹) onto the foliage of secondary coppice regrowth until canopy closure [49]. Typically, this may involve in total two to four applications over two years equating to 1.94 to 3.88 kg a.i. ha⁻¹ annum⁻¹ for each of the two years.

Targeted noxious weed control is carried out periodically in all planted forests, mainly with the use of glyphosate applied at higher rates (2.20 to 3.48 kg a.i. ha⁻¹). The control of noxious weeds is not limited to planted areas which only make up ~70% of the area owned by forest companies in South Africa, but also includes non-afforested and conservation areas.

An estimate of total annual use of glyphosate in planted forests in the USA could not be obtained; however, approximately 1% to 2% of total glyphosate use in the USA is for forest management with the majority associated with use in the agricultural and horticultural sectors [50]. A recent herbicide use survey of industrial forest land (excluding non-industrial privately owned forest land) in the USA provided some information as to the use and application of glyphosate in planted forests [35]. The survey indicated that glyphosate (alone or as a mix) was applied over ~72,000 ha in 2011 and ranked as the fourth most widely used herbicide on industrial forest land [35]. Glyphosate was applied mainly for site-preparation (pre-plant) and mainly broadcast via helicopter, at average use rates of between 1.0 to 3.0 kg a.i. ha⁻¹, although higher use rates were recorded for some sites (up to 7.85 kg ha⁻¹). This use rate equates to an estimated national average for industrial forest land of ~188 tonnes for 2011, noting that inclusion of non-industrial privately owned forest land would increase this estimate (Table 1).

Canada’s vast forested land base (347 million ha) is owned almost entirely by the public, and managed on their behalf by various provincial and territorial governments. At the national level, approximately 66% of the forest land area harvested in any given year is regenerated without herbicide intervention. The remaining 34%, (typically the most productive sites with greatest vegetative competition levels) is replanted to replace harvested conifers, and herbicides are used to ensure effective re-establishment of newly planted seedlings. Detailed records of herbicide use as well as other silvicultural statistics at both the provincial and national level are maintained and publicly accessible through the National Forest Database Program website (http://nfdp.ccfm.org/). Long-term trends continue to show that glyphosate-based herbicides dominate forest sector use patterns, continuously representing more than 95% of the total area treated in each year since 1990. In Canada, aerial applications using either rotary wing or fixed wing aircraft predominate, with ground applications on average since 1992, comprising only about 18% of the total area treated annually, largely for treatments near sensitive areas. Typically, applications are made within 1 to 3 years post-planting and involve rates that vary depending upon province and year, but with long term averages ranging from 1.9 to 3.4 kg a.i. ha⁻¹. In terms of total product applied in the Canadian forest sector, the long term annual average (1992 to 2014) was 290,990 kg with data showing a rather marked trend of decline over the past decade. In Canada, owing to the relative tolerance of spruce and other conifers later in the summer season, glyphosate-based herbicides are applied directly over top of planted seedlings to control diverse mixtures of competing vegetation including both woody and herbaceous competitors, and particularly on rich sites with the greatest competition levels.

Glyphosate is widely used for vegetation control in the management of planted hardwood and softwood forests in Chile applied either alone or in combination with other active ingredients [27]. For pre-plant vegetation control, or site preparation, rates of application vary according to the type of vegetation on site. For post-planting control of competitive vegetation glyphosate is applied manually as a directed spray to the inter-row, or with a shielded boom sprayer if terrain allows, generally at rates of around 2 to 2.5 kg ha⁻¹. As in South Africa, glyphosate is also used in the management of coppice [27] and total use has been estimated to be greater than 200 tonnes per annum.

Herbicide use patterns in forest management in the European Union are generally substantially lower than that for the intensively managed commercial plantations of the southern USA, Australia, South Africa, Chile and New Zealand [32]. However, in a survey of forest vegetation management practices across Europe conducted in 2009, Willoughby et al. [32] reported that glyphosate was the most used forest herbicide in 12 of 18 surveyed European nations. Most application was ground based via knapsack or machine spraying.

The majority of glyphosate-based herbicides, applied either aerially or manually in managed forests, are intercepted by the competing vegetation canopy [51,52,53,54]. Once on the foliage, glyphosate is rapidly absorbed and translocated within the plant [53,55]. The time for glyphosate rain fastness (where the glyphosate has either dried or been sufficiently absorbed to maintain its effectiveness) varies from several hours to several days depending on the characteristics of the targeted weed species and the specific formulation applied [27,53]. Until rainfastness has been achieved, glyphosate is vulnerable to wash-off from heavy dew and rainfall events.

North American studies, across a wide range of environmental gradients, have shown that the majority of glyphosate foliar residues dissipate within a month of application under operational conditions in managed forests. Vegetation characteristics, temperature, humidity and timing of rainfall events (particularly within 24 h of application) were key factors influencing degradation rates [27,51,52,53,54]. The half-life of glyphosate (DT₅₀) is commonly used as a measure of degradation processes and persistence in the environment. The foliar DT₅₀ for glyphosate ranged from less than one day to 14 days where application rates ranged from 1.98 to 3.3 kg a.i. ha⁻¹ [51,53,56]. In a study conducted by Thompson et al. [53], the time for 90% of the foliar glyphosate to dissipate was less than 16 days. Where glyphosate was aerially applied in forests at a higher rate of 4.12 kg a.i. ha⁻¹ (the maximum registered rate and about 3× the normal rate), across a range of climatic zones in the USA, 96% of the glyphosate in the overstorey vegetation dissipated within 30 days [51].

Most studies show that at the time of application the density of vegetation cover is a key factor influencing the amount of glyphosate reaching the forest floor, either from direct spray or spray drift [51,52,54,57]. In the post-application period an initial decline in glyphosate in the upper levels of forest soils was often followed by an increase in concentrations in the following few days or weeks. Sources of residues included dew fall, wash-off from rainfall events, (particularly within 24 h of application), or leaf drop from overhead vegetation (Figure 1), often contributing to large increases in forest floor glyphosate residues [51,52,54,57]. For example, in the Newton et al. [52] study in Oregon Coast Range, mean residue concentrations of glyphosate in forest litter, following aerial application of glyphosate (3.3 kg ha⁻¹) were 5.0 mg kg⁻¹ on the day of application, doubled during a rainfall event the following day, then declining rapidly to 0.2 mg kg⁻¹ by day 55.

Most forest soils are characterised by the presence of litter layers with high organic carbon content and as a result provide an effective sink for glyphosate residues. Glyphosate acid itself is zwitterionic, carrying both a positive and negative charge under typical environmental pH conditions but in different proportions depending upon the exact pH [27,58,59]. It is the zwitterionic character of the glyphosate molecule which is responsible for its tendency to sorb strongly to organic matrices or clay minerals. On reaching the soil environment, either directly or indirectly, the breakdown of glyphosate in forest floor litter and soils is generally rapid (litter: DT₅₀ 8 to 19 days; soil: DT₅₀ 5 to 40 days) [52,54,57], with microbial degradation considered the primary degradation pathway [52,60,61], although there may be some limitations on the ability of microorganisms to completely mineralise glyphosate and its primary metabolite, AMPA [62].

Even when glyphosate remains in forest soils, leaching into aquatic environments is not considered to be a significant transfer pathway [51,52]. This is because for most soils within the typical pH range (4 to 8 pH), glyphosate is present in the form of an anion and bonds tightly to both the organic matter and mineral component of soils, as is indicated in its high sorption constants (Table 2) [22,51,52,58,63]. This is supported by studies on the environmental fate of glyphosate in forest soils, showing glyphosate retention mainly within the top 15 cm of soil depth, with comparatively lower concentrations occurring in the mineral soil layer [52,60,61]. All studies conducted within forest catchments have reported minimal or no evidence of leaching via movement down the soil profile, slope runoff or subsurface flow, irrespective of the soil type, climatic conditions, application rate and the glyphosate product used [51,54,57,61]. For example, even in sandy boreal forest soils in Ontario, Canada, most of the glyphosate (95% at any given time) was retained within the organic layer [61]. Vertical mobility was not observed in forest sites across several regions in the USA [51,54,61].

On the day of herbicide application, glyphosate can potentially enter freshwater environments within forests either from direct spray or spray-drift [69] or possibly accidental spillage [63]. Some of the highest concentrations of glyphosate in water bodies are therefore detected on the day of herbicide application, although these are typically below thresholds of significant biological impacts in terms of both exposure magnitude and duration. The highest concentrations detected have been in association with either operational [52] or experimental over-spraying of waterbodies [56,70] (Table 3). During the immediate post-application period, mobilisation of glyphosate residues from foliage, litter or soil via wash-off from heavy dew, rainfall events, and mobilisation of in-channel or riparian herbicide residues during high flow events, can provide additional sources of glyphosate to aquatic environments [51,56,71]. As discussed, transfer of terrestrial sources of glyphosate to aquatic environments via leaching, run-off or surface erosion, are unlikely to be major input pathways in forested environments and these processes are considered low risk.

Regardless of input pathways, once in the aquatic environment, most forest studies recorded a rapid decline in glyphosate concentrations in waterbodies following herbicide application or rainfall events. Field studies show DT₅₀ for glyphosate of <5 days (Table 3). Glyphosate residues in streams and lentic bodies such as ponds and wetlands typically dissipated to below detection limits within 15 days of application [51,52,56,70,76]. These short time frames indicate a rapid breakdown or reduction of glyphosate in the water column, either by adsorption into benthic and suspended sediments, through microbial breakdown within the freshwater ecosystem (as evidenced by the low and transitory presence of AMPA) or downstream dilution, particularly in lotic water systems [51,52,56,73,76].

The highest potential for glyphosate persistence in aquatic environments is in systems which are deep, cold and relatively biologically inactive or oligotrophic systems. In such systems, glyphosate may be more persistent in both the water column and in bottom sediments. Some studies have documented residues in benthic sediments as being detectable for up to 18 months post-application in forested streams [51,52,56,76]. The high adsorption capacity of sediment for glyphosate has frequently resulted in higher peak concentrations in sediments compared with water (Table 3), that persisted for longer periods of time, even when the active ingredient was present in only small quantities in the water column (Table 3). It is likely that this process is a primary pathway for removal of glyphosate from the water column in forested freshwater environments [52,56,73,77,78].

The World Health Organisation has classified glyphosate as slightly hazardous (Class III) [64]. The toxicology data in Table 2 provides a benchmark, against which to assess the probable risk of glyphosate to planted forest terrestrial and freshwater environments when applied under operational conditions. Although isopropylamine is the main glyphosate salt applied in managed forests (Table A1) for the purposes of the risk assessment, the range of glyphosate salts used by this sector were assumed to have similar toxicological and ecotoxicological profiles [65,79]. This is intuitively reasonable since upon release into most natural environments all glyphosates salts readily dissociate to yield the glyphosate free acid molecule.

Given that glyphosate is an herbicide, non-target vegetation is particularly at risk, primarily from spray drift or accidental over-spraying. North American studies across a wide range of environmental gradients have shown that the majority of glyphosate foliar residues dissipate within a month of application under operational conditions in managed forests, indicating that the period of greatest risk for off-site transfer, is the immediate post-application period. The rapid uptake in plants and strong sorption to soils, clay minerals or other organic materials essentially immobilize glyphosate and minimise off-site movement unless there are major storm events within a few hours of treatment or where surface water flows are so great they are actually mobilizing soil particles with adsorbed glyphosate.

Terrestrial fauna residing in forested areas treated with glyphosate are potentially at risk of exposure to glyphosate via direct spray, spray drift or wash-off following rainfall events, and uptake via inhalation and absorption, (Figure 1), although there is little information available on this [80]. Secondary exposure is also possible through the ingestion of flora and fauna food sources containing glyphosate residues [52]. The risk of bioaccumulation through secondary exposure to glyphosate is known to be low, based on its low octanol-water partition co-efficient (logP Kow) (Table 2), well below the octanol-water partition co-efficient of 5.0 or greater suggested by Mackay and Fraser [81] as a threshold for the onset of bioaccumulation. In addition, studies have documented facile depuration via urine and faeces and a lack of significant residues accumulating in animal tissues [52,54]. In both these studies, glyphosate residues in the viscera, stomach contents and tissue samples of a range of small and large mammals were at or below concentrations found in ground cover and litter residues, indicating that glyphosate was not bioaccumulating in higher trophic levels.

Studies have generally reported minimal impacts from glyphosate applied under typical application rates in forests, on litter decomposition, soil microbial communities and soil microbial processes. Fletcher and Freedman [82] conducted laboratory studies with two leaf litter and one forest floor substrate and found that the threshold for glyphosate effects on litter decomposition was more than 50 times higher than residue concentrations that occur in the field after silvicultural herbicide treatments. In another laboratory study, Castilho et al. [83] found that a range of glyphosate products, applied at doses within the range used in managed forests, had no significant impact on microbial activity in forest soils. Soil DT₅₀’s in the forest field studies discussed in the ‘Fate in litter and soils’ section above, were at the low end of the range reported in Table 2. Peak glyphosate concentrations measured in planted forest litter and soils [51,52,54,57] were ~1 to 2 orders of magnitude lower than the LC₅₀ for earthworms (Table 2). Edwards and Bohlen [84] also noted that glyphosate at exposures ranging from 1 to 100 ppm in soils had no toxic effects on earthworms. In Ontario, Canada, microbial processes and fungal community structures were unaffected by glyphosate (1.5 kg a.i. ha⁻¹) with only minor effects evident at the species level. In fact, soil type had a greater influence with microbial processes significantly higher in organic soils compared with mineral soils [85].

At experimentally higher application rates, glyphosate (3 kg a.i. ha⁻¹) manually applied over a 7–9 years period to Pinus ponderosa stands in California, USA, showed minimal effects on soil microbial communities over a range of soil types [86], where site productivity (characterised by site index) and seasonal factors had a greater influence on soil microbial community characteristics. These results concur with Durkin’s [8] assessment that terrestrial microorganisms were unlikely to be adversely affected by glyphosate. However, Ohtonen et al. [87] examined microbial processes in a clear-cut forest in Ontario Canada, following annual glyphosate applications experimentally applied over a five year period and observed reduced microbial biomass carbon (C), microbial carbon, soil organic carbon ratio (Cmic/Corg), and decreased fungal biomass relative to bacterial biomass.

Field studies on the aquatic fate of glyphosate in managed forests (Table 3), indicate that the concentrations and duration of glyphosate typically measured, with the exception of direct over-spraying of wetlands [70], were well below the standard toxicity endpoints for fish and other aquatic organisms (Table 2) [71,88,89], often by orders of magnitude. In forest operational scenarios, the aquatic systems most likely to be over-sprayed are small shallow wetlands and low-order streams that are difficult to detect or avoid during aerial spray applications. Therefore the results of experimental over-spraying of these types of waterbodies as shown in Table 3 provide a surrogate measure of risk for this type of situation.

Amphibians, with their thin permeable skins, are potentially at risk from exposure to glyphosate [8]. In the case of Thompson et al. [70], the authors estimated an upper 99th centile glyphosate concentration of 0.55 ppm (550 µg L⁻¹) following chemical monitoring of directly over-sprayed wetlands in Ontario, Canada. Coincident biomonitoring showed no significant toxic effects on two species of sensitive amphibian larvae caged within the multiple wetlands under study. Furthermore, in situ enclosure field studies in either ponds in northern Ontario or in small wetlands in New Brunswick Canada, showed no significant effects on amphibian survival, growth or development when directly exposed to formulated glyphosate-based herbicides even at the maximum permissible label rates [77,78,90,91]. These results were similar to a field study in Oregon USA, assessing the effects of clear-cutting and clear-cutting followed by glyphosate application where no herbicide effects were observed for six species of amphibians [92].

Folmar et al. [89] noted that there was a potential risk to young-of-year fishes from glyphosate exposure in lentic bodies where dissolved oxygen levels are low or water temperatures are high, highlighting the sensitivity of these environments which lack the downstream dilution processes of running waters. In a comprehensive watershed level investigation on the effects of a glyphosate-based herbicide applied to a western Canadian coastal forest system [54,56], temporary stress effects and minor mortality (2.6%) were observed in caged coho salmon (Oncorhynchus kisutch) fingerlings held in an experimentally over-sprayed tributary and the main stream below the sprayed area in the immediate post-application period. However, no acute mortality, changes in over-winter mortality, growth rate or probability of using the tributary were observed for resident fingerlings [93]. Kreutzweiser et al. [94] also reported minimal effects on the drift patterns of stream insects in these streams. A New Zealand study also found no significant interactions between fine sediment and benthic invertebrates when exposed to glyphosate. Instead, sediment had a greater impact on a range of invertebrate indices compared with glyphosate concentration [95]. More recently, field monitoring studies conducted in Oregon showed that although multiple trace level detections of glyphosate were found in streams draining forested watersheds treated with glyphosate, cumulative time weighted exposure estimates resulted in a margin of safety approximating 100 fold for toxic effects on sensitive aquatic organisms [71]. As glyphosate salts and the free acid are highly water soluble, the risk of bioaccumulation in the aquatic environment is known to be very low (Table 2) [88] and in the Newton et al. [52] study, no glyphosate bioaccumulation was detected in coho salmon fingerlings.

As discussed, sediment sorption and degradation of glyphosate and associated surfactants has been identified as a primary removal mechanism for glyphosate from the water column in forested freshwater environments, a potential source of risk, particularly to sediment dwelling, organisms. However, these risks are tempered by the strong ionic sorption mechanisms which are considered to limit leaching or diffusion into the water column and bioavailability of sediment-bound residues [51,52,73,96], significantly reducing toxic effects. Nonetheless, experimental testing of sediment microbes exposed to environmentally relevant and high concentrations of glyphosate in lake sediments detected changes in community composition at glyphosate concentrations of 150 µg kg⁻¹ dry weight [97] and laboratory tests by Tsui and Chu [98] found that sediment additions enhanced the acute or chronic toxicity of glyphosate-based formulations, particularly for filter-feeding organisms. In contrast, Wang et al. [96] found that sediment sorption reduced the toxicity of the surfactant polyethoxylated tallow amine (POEA), commonly used in glyphosate products and a primary toxicant for aquatic organisms, such as Daphnia magna. In wetland field studies, Baker et al. [99] showed a transient decline in plankton communities following coincident exposure to glyphosate and nutrients, but not glyphosate alone, suggesting that indirect or interactive effects with other stressors in aquatic communities are possible. These results highlight a need for further research on the potential indirect effects of glyphosate and surfactants which may be present in the sediments of aquatic environments for somewhat longer periods of time and particularly where such residues might interact with other stressors imposed by management of planted forests.

The field studies referred to in this review have assessed the environmental impact and risk of the entire formulated product. When exposed under laboratory conditions, fish and amphibian larvae are known to be highly sensitive to various surfactants such as POEA, which are included in most glyphosate-based herbicide formulations used in silviculture and that the expressed toxicity is also dependent upon pH, hardness and other characteristic of the aqueous medium, e.g., [8,72,89,98,100,101,102]. However, reviews by several authors on the potential environmental effects of formulated glyphosate products primarily used in North America [4,5,6,7,19], consistently conclude that the direct acute toxic effects to aquatic organisms are unlikely under realistic environmental exposure regimes in forests. This viewpoint is supported by the results of field studies on forest operational exposure to glyphosate products, as reviewed above, where significant direct toxic effects were not observed providing a posteriori support for the established threshold concentrations for glyphosate considered to be non-toxic for all aquatic life [88] (Table 4).

Indirect effects of glyphosate to both terrestrial and aquatic fauna have been associated with changes in plant community composition, habitat structure, cover, and food sources and are primarily a consequence of glyphosate’s phytotoxic effects rather than a result of ecotoxic qualities unique to the active ingredient [80,99,107,108,109,110]. Studies on small mammals (i.e., rodents, shrews, voles, chipmunks) showed that some short-term changes were observed at the species [111,112,113] and functional feeding group level [114], which the authors attributed to the reduction in invertebrates, plant cover and food. At the population level, glyphosate did not appear to have significant or long-lasting effects in the first few years after application [112,114,115]. Similar to small mammals, changes in bird community composition, and reductions in abundance, densities and species richness of bird populations often occurred in the first few years after glyphosate application [80,116,117,118], and in the case of Santillo et al. [117] the decline in bird densities was correlated with the decline in habitat complexity. These changes were assessed against untreated control sites to differentiate the effects of glyphosate from other background environmental factors such as the recovery trajectory following tree harvest and showed similar responses to other herbicides commonly used in managed forests [119]. Fewer studies are available on the indirect effects of glyphosate on terrestrial arthropods and results show a wide range of responses most likely in response to the organism’s affiliation with and dependency on, habitat components affected by the glyphosate treatments [80]. Similarly, in aquatic systems, direct acute toxic effects are typically not observed at under realistic environmental exposure scenarios, however, indirect effects including restructuring of zooplankton and macroinvertebrate communities may occur if glyphosate-based herbicides are directly applied, for experimental purposes, at maximum label rates to small wetlands [99,107].

Less is known about the more subtle long-term indirect, synergistic and cumulative stressor effects of glyphosate in forested environments. Laboratory studies involving exposures to 58 and 116 µg L⁻¹ glyphosate for 1 and 3 days have identified DNA damage in long-lived freshwater eels [120,121] and a New Zealand study found that the synergistic effects of glyphosate (exposure rate 360 µg L⁻¹ for 26 days) and parasitic infections significantly affected the survival of a juvenile stage of native fish species (Galaxias anomalus) [122]. Further research is needed to assess the sub-lethal, long-term effects of glyphosate at rates used under forest operational conditions and to separate glyphosate effects from those of any other additives commonly used in forests.

In summary, toxicity results from laboratory and mesocosm studies on glyphosate products have rarely translated into similar toxic effects in the field when applied according to product label and best operational practices. As discussed, these results have been attributed to the rapid dissipation, sorption to soil, sediment and organic matrices, and microbial degradation processes in forested terrestrial and aquatic environments, reducing exposure time and duration for biological uptake of glyphosate and surfactants such as POEA. This outcome emphasises the need for a precautionary approach when extrapolating results from the laboratory to predict the effects and risks of glyphosate products on non-targeted organisms and environments in forested ecosystems. However, it should be noted that these results are based primarily on North American glyphosate-based products and information on the environmental effects of glyphosate-based products used in managed forests elsewhere is either minimal or absent [8].