Chemical Site Preparation Research Articles

Chemical Site Preparation Mixtures, Application Timing, and Herbaceous Weed Control Impacts on Loblolly Pine Development Through Six Years

Abstract Chemical site preparation is a critical management practice for southern pine plantation establishment. Imazapyr and ester triclopyr are frequently used for chemical site preparation in the Lower Coastal Plain to control waxy leaf shrub species, yet limited information is available on optimal imazapyr and triclopyr tank mixes and individual herbicide application timing(s) to achieve maximum loblolly pine (Pinus taeda L.) growth. The objectives of this study were to determine the survival, growth, and stem defect response of 6-year-old loblolly pine to four chemical site preparation treatments plus an untreated control, three application timings, and first year herbaceous weed control (hwc) on a poorly drained flatwoods site. Treatments included two imazapyr and triclopyr rates applied as tank mixes, triclopyr and imazapyr alone, and an untreated control with hwc applied to half of each treatment plot. Results showed no treatment had superior survival or growth, whereas September-applied imazapyr and triclopyr tank mixes tended to result in improved growth. Triclopyr alone along with first year, banded hwc resulted in similar growth to imazapyr and triclopyr tank mixes. First-year hwc significantly enhanced survival and growth. Stem defects were more common in the chemical site preparation treatments than the control. Study Implications: Age-6-year results from this study indicate that loblolly pine (Pinus taeda L.) growth following application of chemical site preparation tank mixes containing imazapyr and triclopyr applied during September or October tended to be superior to July applications. Triclopyr applied alone with first growing season herbaceous weed control (hwc) may offer satisfactory near- and long-term loblolly pine growth as imazapyr and triclopyr tank mixtures on sites with similar competing vegetation. These findings may allow for less herbicide use on sites previously managed for pine production and show the importance of first year hwc for Coastal Plain flatwoods sites.

Current forest management intensity and cost associated with major forestry practices in Arkansas, USA

Arkansas’ forestlands are largely owned by private landowners: family, industrial or corporate forest landowners (5.1 million hectares; 67%). Family forest landowners own 4.4 million hectares of forestland (58%). The costs of forestry practices influence landowners’ decisions in forest management. However, state-specific costs for forestry activities are not readily available. The study aims to compare the forest management objectives between family and industrial or corporate forest landowners and also provide robust information about forest management intensity and the unit cost associated with those activities. We employed an online survey to 318 consulting foresters working in the state. In addition, we used Forest Inventory and Analysis dataset in ArcMap (10.8.1) to validate the survey result. Among various forestry practices, landowners requested various services from consulting foresters, including chemical site preparation, thinning, timber cruising and marking, and timber inventory. The unit cost for mechanical site preparation was the highest among several forestry practices, and these costs varied based on forest types. Various stakeholders can utilize the study findings from landowners, forest industries, and policymakers in forest investment decision-making, which can improve sustainable forest management.

Immediate effects of chemical and mechanical soil preparation techniques on epigaeic arthropod assemblages during reclamation of in situ oil and gas sites in northern Alberta, Canada

Epigaeic arthropods have been used worldwide as indicators of post-disturbance recovery in many different types of ecosystems. We used them to evaluate the merit of different reclamation prescriptions applied to areas disturbed by oil and gas exploration and extraction. We compared the short-term effects of different mechanical and chemical site preparation techniques on the epigaeic arthropod fauna of previously reclaimed borrow pits in arrested succession with results from plots in untreated disturbed sites and undisturbed adjacent forest. In general, arthropod diversity increased and abundance decreased with the severity of soil disturbance involved in the silvicultural prescription. We place arthropod communities into four discrete groups reflected in the treatments and the environmental characteristics of the sites: forest species, grassland species, species primarily found in herbicide plots, and species found in disturbed soil. Individual borrow pits accounted for a significant amount of variation in faunal assemblages, suggesting that site location, vagaries of colonization, or disturbance history play a significant role in how the fauna recovers post disturbance. Our study provides baseline data required to document the trajectory of recovery in these sites. Long-term monitoring is essential to evaluate the relative usefulness of reclamation prescriptions in meeting targets established by law.

Allocation versus completion: Explaining the distribution of the Forest Development Program fund in North Carolina

The Forest Development Program (FDP) is a nationally renowned state-administered cost-share assistance program for forest landowners in North Carolina, primarily funded through taxation on primary forest products across the state. While the demand for FDP cost-share funds often exceeds available resources, over one-fourth of annual allocations on average go unused, due primarily to application cancellations and the divergence of actual costs and treated acres from the amounts approved originally. This study evaluates various factors related to the utilization of allocated funds based on actual cost-share fund usage data in the last six years. Results suggest that FDP applications associated with the piedmont region, shearing and chemical site preparation, hand-planting activities, and larger applied acres are more likely to be completed as defined in the initial application. The methods and findings of this study provide useful insights to administrators of other similar public incentive programs. The need for similar analyses evaluating the utilization of public funds will likely grow as state and federal governments increasingly rely on incentive programs to meet ambitious goals in conservation and sustainable management of natural resources.

Long-term effects of group opening size and site preparation method on gap-cohort development in a temperate mixedwood forest

Management aimed at regenerating softwoods and hardwoods in the same stand (i.e., a mixedwood) has some appeal in the pine-hardwood forests of the southern United States. We revisited a group selection experiment installed in 1991 to evaluate the influence of gap size and site preparation treatments on a pine-hardwood stand in Louisiana, USA. Experimental treatments included a factorial combination of three group opening sizes (0.1, 0.25, 0.4 ha) and three methods of site preparation (chemical, mechanical, untreated) in the harvest gaps. Specifically, we tested two hypotheses: 1) regeneration of shade-intolerant tree species increased with gap size and the addition of site preparation and 2) if this site preparation decreased the regeneration of species that are more tolerant of shade and reliant on advance reproduction. In 2016, the density and basal area of the shade-intolerant loblolly pine (Pinus taeda), shortleaf pine (Pinus echinata), and sweetgum (Liquidambar styraciflua) increased with increasing gap size (P < 0.05), supporting our first hypothesis. Compared to untreated gaps, white oak (Quercus section Quercus), red oak (Quercus section Lobate), and red maple (Acer rubrum) abundances were significantly reduced in gaps treated with chemical or mechanical site preparation, supporting of our second hypothesis. Based on these results, it appears possible to secure adequate pine regeneration with a relatively wide range of early gap-treatment option in similar pine-hardwood forest types. However, pines dominated nearly all gaps (regardless of treatment), so much so that many no longer qualify as mixedwood. This outcome suggests that managers interested in group selection for mixedwoods in this part of the coastal plain should consider creating larger gaps (≥0.25 ha) in areas with preferred hardwood advance reproduction, while limiting within-gap site preparation to help protect it.

Eight-year performance of bareroot Douglas-fir and bareroot and plug western larch Seedlings following herbicide applications, northeast Oregon, USA

Plantation success in northeastern Oregon can be limited by poor survival for western larch (Larix occidentalis Nutt.) and Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. glauca (Beissn.) Franco) seedlings. Vegetation management treatments may increase soil moisture availability during the dry summer months, thereby increasing the probability of seedling survival. Chemical site preparation treatments were applied in spring 2007, summer 2007, and spring 2008 to determine if such treatments would improve survival and growth of bareroot Douglas-fir and bareroot and plug western larch seedlings on three sites near Elgin, Oregon. Although some herbicide treatments significantly increased survival, results were not consistent among sites. Overall, Douglas-fir had greater survival after 7–8 years than larch seedlings. Seedling size 7–8 years after planting was also highly variable among sites and treatments with larch seedlings being taller and larger than Douglas-fir seedlings, on the average. Size for all stock types was negatively correlated with vegetative cover and positively correlated with first-year soil moisture. Macro- and microclimatic conditions, including topography and soil depth, were likely contributors to differences in survival and growth.

Responses of white‐tailed deer and northern bobwhite food plants to a gradient of stand‐establishment intensities in pocosin pine plantations

AbstractLoblolly pine (Pinus taeda) plantations are established using various treatments to manage competing vegetation and increase pine production. Although young pine plantations historically supported early successional vegetation communities that contained abundant wildlife forage, increasing intensity of stand‐establishment treatments, particularly herbicides, has caused concern regarding potential effects on composition, availability, and quality of wildlife forage within young pine plantations. Few long‐term studies have described relationships between intensity of site preparation and effects on important forage plants for 2 economically and ecologically important game species: white‐tailed deer (Odocoileus virginianus) and northern bobwhite (Colinus virginianus). Therefore, we examined effects of 6 treatments of increasing stand‐establishment intensity via combinations of mechanical and chemical site preparation with herbaceous weed‐control on deer and bobwhite food plants from 1 year to 8 years after site preparation in loblolly pine plantations (n = 6) within pocosins in the Lower Coastal Plain of North Carolina, USA, during summers of 2002–2005, 2007–2009. Although woody and vine forage plants for deer and quail were common on all treatments, chemical site preparation resulted in long‐term decreases (approx. 50% for 8 yr) in coverage of these plants. Type of mechanical site preparation–spacing and herbaceous weed‐control had few effects on woody and herbaceous deer and quail food plants. Dissimilar from research in other regions, reduction in woody cover did not provide a concurrent increase in herbaceous food plants. Because of relatively poor forage quality in pocosin habitats, vegetation management practices may reduce deer and quail food quantity without increasing quality. However, because abundance of low‐quality forage is high in pocosin habitats, localized forage reductions due to site‐preparation techniques may not affect overall carrying capacity in these areas. © 2012 The Wildlife Society.

Bird community dynamics and vegetation relationships among stand establishment practices in intensively managed pine stands

Intensively managed pine occupies 22% of the forest land base in the southeastern United States. More fully understanding effects of standard silvicultural practices on biodiversity could improve wildlife management recommendations on intensively managed landscapes. Although multiple stand-establishment techniques (i.e., site preparation and chemical herbaceous control of competition) are used for forest regeneration, we lack an understanding of causal mechanisms for bird community responses during stand establishment through canopy closure. Therefore, we investigated bird community responses to five stand-establishment treatments in intensively managed pine (Pinus spp.) stands in the Lower Coastal Plain of Mississippi, USA as a function of changes in vegetation structure and coverage. We used a randomized complete block design of four pine stands (blocks) divided into five experimental units and with treatments randomly assigned to each unit. Our treatments represented available establishment practices and increased in intensity from mechanical or chemical site preparation with subsequent banded herbaceous control to mechanical and chemical site preparation with 2years of subsequent broadcast herbaceous weed control applications. We sampled bird communities with point counts and measured visual obstruction, pine tree height, woody stem density, and vegetation structure and coverage by growth form (e.g., forb, fern, grass, legume, pine, sedge and rush, woody non-pine, vine). Bird communities had an overall negative response to increasing intensity of stand-establishment treatments, and temporal trends from site preparation to canopy closure were absent. Common species appeared relatively unaffected by treatments. However, presence of species with high conservation value and availability of early successional habitat conditions emphasized conservation potential of intensively managed pine forests for birds and justify further experimental investigation of bird community responses to stand-establishment treatments. We recommend forest managers continue to incorporate a variety of stand establishment practices to ensure habitat availability for a variety of bird species, and that researchers further investigate mechanistic factors of avian community responses to silvicultural practices.

Successional trajectory of loblolly pine ( Pinus taeda) plantations established using intensive management in Southern Mississippi, USA

Although secondary succession in commercial pine plantations offers opportunities to manage for biodiversity, questions remain regarding effects of stand establishment intensity on biodiversity. Therefore, we examined 9 years of post-harvest plant succession in loblolly pine plantations established under a range of intensive management regimes in Mississippi, USA, including combinations of mechanical site preparation, chemical site preparation, and herbaceous weed control. We evaluated plant community structure using coverage of eight growth forms, and community composition using species-level coverage. Stands established without chemical site preparation retained more post-harvest woody and vine species and had less variable species turnover than chemically prepared stands. Chemically prepared stands provided opportunity for greater expression of early succession herbaceous and subshrub communities. Broadcast herbaceous weed control reduced expression of the early succession community relative to banded applications, but a single broadcast application did not prevent strong re-emergence of that community the following year. Conversely, multiple broadcast applications of herbaceous weed control reduced expression of early succession species beyond the year of final treatment, possibly through inhibiting establishment until favorable conditions were past, rather than by directly favoring woody dominance. Plant community structure converged as crown closure approached, and structural differences were largely insignificant by year 5. However, small differences in composition that may affect biodiversity were retained and may last until midrotation harvest and subsequent treatment. Greater diversity of plant communities in stands with chemical site preparation may benefit biodiversity in establishing plantations if not inhibited by broadcast herbaceous weed control. Resources committed to broadcast weed control may be more usefully diverted to midrotation management that improves biodiversity after thinning. These results can be used to target management of early succession species at stand and landscape scales. Given the known effects of this limited array of treatments on biodiversity, additional establishment regimes should be monitored to provide information critical to meeting stand- and landscape-level biodiversity goals.

Bird community responses to a gradient of site preparation intensities in pine plantations in the Coastal Plain of North Carolina

Although intensively managed pine forests are common in the southeastern US, few studies describe how combinations of mechanical (MSP) and chemical site preparation (CSP) and herbaceous weed control (HWC) techniques affect bird communities that use early successional habitats within young pine forests. Therefore, we examined effects of six treatments of increasing management intensity via combinations of MSP (strip-shear and wide spacing or roller chop and narrow spacing) and CSP (application or no application) treatments with banded or broadcast HWC on bird communities in six loblolly pine ( Pinus taeda) plantations in the Coastal Plain of North Carolina, USA, for 8 years following site preparation. Wide pine spacing and strip-shear MSP increased bird abundance and species richness over narrow spacing and chopped MSP for 6 years after planting. Chemical SP reduced bird abundance in year 2, increased bird abundance in year 6, had no effect on abundance after year 7, and did not affect species richness in any year. Total bird abundance and species richness were similar between banded and broadcast HWC. Site preparation and HWC had no effect on bird diversity and bird communities were most similar in treatments of similar intensity. Site preparation and HWC had few or no effects on birds based upon migratory status, habitat association, or conservation value. The addition of chemical site preparation or HWC had little effect on birds beyond pine spacing, and bird abundance was not proportional to management intensity. Although we observed treatment effects, all treatments provided habitat used by a variety of bird species, and pine plantations may play an increasingly important role in bird conservation as forests become fragmented and converted to other land uses and as natural processes that create early successional habitat, such as fire, are suppressed.

Influence of post-harvest silviculture on understory vegetation: Implications for forage in a multi-ungulate system

Natural disturbance emulation has emerged as a key management approach to maintaining biodiversity in logged boreal forests. Forest managers’ success in emulating understory forest ecosystem functions, e.g., for the provision of habitat even for large mammals, has not been tested due, in many cases, to incomplete records of silviculture. We examined regenerating areas of previously conifer-dominated forests in northwestern Ontario, Canada, 10 and 30 years after logging and 10 and 30 years after fire to test if understory development and moose ( Alces alces) forage abundance differed between the two disturbance types and artificial or natural regeneration approaches. In addition, we counted moose pellet groups as a measure of moose use of the region. Specific treatments included: (1) naturally regenerating, fire-origin forests, (2) post-harvest, regenerating forests with natural establishment of trees, and (3) post-harvest, regenerating forests with mechanical or chemical site preparation and planting and/or herbicide spraying. We hypothesized that the understory in post-harvest stands would support higher forage availability for moose compared to similarly-aged, fire-origin stands. Abundance of hardwoods, shrubs, and herbaceous plants was greater in naturally-regenerated post-harvest stands than in fire-origin and artificially regenerated post-harvest stands at both 10 and 30 years post-disturbance. However, post-harvest, naturally regenerating stands were not significantly associated with higher moose use, rather evidence of moose use increased as a function of the amount of naturally regenerating logged forest in the surrounding landscape. This study suggests that, relative to fire, the intensity of post-harvest silviculture influences habitat suitability for moose. The effect likely cascades to other ungulates, such as woodland caribou ( Rangifer tarandus caribou), and vegetation management needs to be considered at scales greater than the stand level in order to achieve habitat management for large mammals.

Plant community responses to a gradient of site preparation intensities in pine plantations in the Coastal Plain of North Carolina

Intensively managed loblolly pine ( Pinus taeda) forests are common in the southeastern United States and offer opportunities for conservation of biologic diversity. Within intensively managed landscapes, stand establishment relies on combinations of mechanical and chemical site preparation and herbaceous weed control (HWC) to manage competing vegetation and increase pine production. However, few long-term studies have described relationships between intensity of stand establishment and effects on plant communities. Therefore, we examined effects of 6 treatments that varied in intensity via combinations of mechanical (wide spacing and strip shear or narrow spacing and roller chop) and chemical (application or no application) site preparation treatments with HWC (broadcast or banded) from 1 to 8 years after site preparation on plant communities in loblolly pine plantations ( n = 6) in the Coastal Plain of North Carolina, USA. All treatments resulted in abundant and diverse plant communities. Chemical site preparation had short lived (⩽4 year) effects on the herbaceous community but long-term effects on woody plants and pine cover. Increasing management intensity by including broadcast HWC or roller chop/narrow spacing did not additively reduce woody vegetation cover or species richness. However, broadcast HWC reduced grass, vine, and forb cover in the first year post-treatment. Average Morista community similarity values ranged from 0.69 to 0.89 among treatments and plots receiving the same chemical site preparation contained the most similar plant communities. Banded HWC can be paired with wide spacing to maximize herbaceous plant growth important for many wildlife species, particularly in the first few years after site preparation. Site preparation techniques should be tailored to local site conditions, plant communities, and management objectives.

Growth Response of Loblolly Pine (Pinus taeda L.) 3–5 Years After Plantation Establishment Using Different Management Intensities

The upward trend of intensive management in Southern pine forests is expected to continue, both in area and intensity level. Much of the Mississippi Lower Coastal Plain (LCP) is managed intensively using some combination of mechanical site preparation, chemical site preparation, and herbaceous weed control (HWC). We studied pine growth response and competition control on loblolly pine (Pinus taeda L.) plantations 3–5 years following establishment using five combinations of chemical site preparation, mechanical site preparation, and HWC. Treatments were designated a priori as 1 (least intensive) through 5 (most intensive) largely on the basis of anticipated impact on the vegetation community. We measured pine height and diameter at breast height (dbh); woody stem density; hardwood basal area (BA); coverage of herbaceous plants, understory woody plants, and pine trees; and estimated differences in pine response using age-shift calculations at age 5. Pine height and dbh were correlated with treatment intensity; treatment 5 maintained an average advantage of 1.4-m height and 2.5-cm dbh over treatment 2, the least responsive treatment. Woody stem density varied widely and was not affected by treatment; understory woody coverage was also unaffected by treatment. Coverage of herbaceous plants was reduced in treatments receiving broadcast HWC, and in treatment 2, where slower establishment of pines may have acted as a release for competing woody plants. Age-shift gains relative to treatment 2 ranged from 0.4–1.0 years. Based on year 5 measurements of hardwood BA, it is likely that treatments 1 and 2 will fall further behind treatments 3–5 as the stands mature. Greatest control of competing vegetation and maximum growth of pines was achieved with the most intensive treatment.

The Effects of Forestry Site Preparation on Mountain Beaver Demographics and Associated Damage to Tree Seedlings

Abstract Timber resources are a vital part of the economy in the Pacific Northwest, yet reforestation efforts are often hampered by animal damage. Understanding the factors that influence seedling damage can assist managers in implementing appropriate techniques to reduce species-specific damage. I radio-collared and monitored mountain beavers (Aplodontia rufa) from preharvest to seedling planting to determine the impacts of forest management practices on demographics. In addition, I monitored Douglas-fir (Pseudotsuga menziesii) seedlings on 28 plots on two harvest units (Vesta and Schoolhouse) to determine the effects of chemical site preparation on mountain beaver foraging and subsequent seedling damage. Mountain beaver densities differed between silvicultural treatments (F3,39 = 3.58, P &lt; 0.02), although reproductive success did not (χ2 = 0.14, df = 1, P = 0.70). Larger mountain beaver home ranges were documented in the mature timber compared with those following harvest. Home ranges were also larger in the chemical site preparation portion of the unit (mean = 3.37 ± 0.9 ha) than in the nontreated portion of the unit (mean = 0.82 ± 0.17 ha) on Vesta. Herbicide treatment did not promote seedling damage on either unit. Vegetation does not appear to be the only factor influencing mountain beaver movements and seedling damage. Availability of water is very important for mountain beavers and may also influence their foraging choice, as well as contributing to their increased movements in mature timber (reduced groundwater) versus clearcut areas. Understanding the effects of vegetation on population demographics and subsequent seedling damage may allow for initiating a nonlethal management method using alternative forage.

Habitat Value of Intensively Established Pine Plantations for Northern Bobwhite

ABSTRACT Declines in northern bobwhite (Colinus virginianus; bobwhite) populations in the southeastern United States may be partially attributable to loss of early successional plant cover associated with greater use of herbicides in forest management. We tested effects of 5 levels of operational plantation establishment intensity on vegetation communities and structure important for bobwhite in 1–5‐year‐old loblolly pine (Pinus taeda) plantations (n = 4) in the Outer Coastal Plain Mixed Forest of Mississippi. We compared results with values reported in the literature to calculate usable space for winter food, loafing, nesting, and brood‐rearing at 2 levels of spatial resolution. Treatments (k = 5) reflected a range of management intensities and were combinations of mechanical site preparation, chemical site preparation (CSP), and herbaceous weed control (HWC). Coverage of winter food plants in the least intensive treatment was more than double that in the most intensive; however, differences in usable space of winter food cover were negligible due to improved accessibility in more intensive treatments. Although CSP reduced coverage of nonpine woody plants across all years, loafing cover reached adequate levels by year 3 in all treatments. Usable nesting cover was &lt;4% across all years and treatments and was nearly eliminated by the reduction in herbaceous cover and visual screening cover following broadcast HWC. Optimal brood‐rearing habitat was virtually absent in all treatments and years due to the lack of conjoint occurrence of bare ground and forb canopy. Although bobwhite habitat may have been promoted by formerly widespread plantation establishment methods that involved wide‐scale soil disturbance, those established using newer methods with less soil disturbance are likely inadequate for most bobwhite habitat requirements. Efforts to provide bobwhite habitat in plantation‐dominated landscapes may have to rely on management of thinned mid‐rotation stands and permanent landscape features such as rights‐of‐way. The value of young plantations for bobwhite may be increased by reducing management intensity or increasing spacing between planting rows, thus increasing time before crown closure and providing opportunity for understory manipulations.

White‐Tailed Deer Foraging Habitat in Intensively Established Loblolly Pine Plantations

ABSTRACT Stand establishment techniques involving multiple herbicide applications are commonly used on industrial pine (Pinus spp.) plantations, raising concern over potential effects on white‐tailed deer (Odocoileus virginianus) forage production. We tested effects of stand establishment intensity on deer forage in 1–5‐year‐old loblolly pine (Pinus taeda) plantations (n = 4) in the East Gulf Coastal Plain of Mississippi using forage biomass and 4 measures of nutritional carrying capacity that reflected crude protein or digestible energy requirements for body maintenance and lactation. We also assessed whether forage biomass combined with a deer use rating effectively indexed nutritional carrying capacity. Treatments were combinations of mechanical site preparation, chemical site preparation (CSP), and herbaceous weed control (HWC). Total forage biomass and forage biomass of grasses and forbs were reduced by broadcast HWC. Forage biomass of vines was reduced both by CSP and by multiple broadcast HWC applications. Maintenance‐level carrying capacity estimates were reduced by broadcast HWC; lactation‐level estimates were higher in moderate‐intensity treatments. We believe the inherently low fertility of this region makes high‐quality forage production a more important management priority than increasing forage quantity. Chemical or chemical and mechanical site preparation combined with banded HWC provided the best option for providing both forage quality and quantity in open‐canopied, intensively managed pine plantations. Biomass‐based indices may be suitable for indexing protein‐based maintenance‐level carrying capacity in this region, but our results indicated they were not useful for indexing other carrying capacity estimates.

Long-term effects of site preparation and postplanting vegetation control on Picea glauca survival, growth and predicted yield in boreal British Columbia

The 19–20-year effects of mechanical site preparation, windrow burning, chemical site preparation, and postplanting vegetation control on survival and growth of planted white spruce are reported from two boreal sites in British Columbia, Canada. Survival differed between treatments at both sites, but was relatively good (≥77%) even in untreated plots. Current data regarding the proportion of spruce that were physically overtopped by vegetation and previous results from related soils and vegetation studies suggest that lasting reductions in tall shrub and aspen abundance were more important to spruce growth than early microenvironmental effects associated with manipulating the rooting environment. At Inga Lake, postplanting vegetation control produced a 13-fold increase in spruce volume over the control after 19 years, which was statistically equivalent to increases resulting from fine mixing, plow-inverting and windrow burning site preparation treatments. At Iron Creek, chemical site preparation and plow-inverting quadrupled spruce volume, whereas mounding, patch scarification and disc trenching were ineffective. Growth and yield simulations using treatment-specific site index curves for Inga Lake suggested that rotation length could be shortened by 12–16 years through the use of site preparation or postplanting vegetation control. However, untreated areas, due to the relatively good survival of white spruce at age 19, were predicted to produce equivalent volume if left to grow to mean annual increment culmination age.

Vegetation community responses to different establishment regimes in loblolly pine ( Pinus taeda) plantations in southern MS, USA

Management treatments involving multiple herbicide applications are standard procedure on most industrial pine plantation sites in the southern USA, raising concerns about biodiversity impairment. Management decisions impact not only plant communities but also the habitat potential they create for wildlife. We tested the effects of five intensities of stand establishment treatments on vegetation communities in loblolly pine plantations ( n = 4) to age 5 in the Middle Coastal Plain (MCP) of Mississippi. Measurements were species richness, diversity, coverage, and community composition. Treatments were combinations of mechanical site preparation (MSP), chemical site preparation (CSP), and herbaceous weed control (HWC) both banded or broadcast for 1 or 2 years using the same herbicide mixtures. Tree richness and diversity were reduced by increasing treatment intensity; tree coverage, which included crop and non-crop trees, was less in moderate-intensity treatments. Vine richness and coverage were less in more intensive treatments, but 2 diversity indices differed on whether vine diversity was likewise affected. Richness and coverage of forbs and graminoids was lessened by broadcast HWC, with effects mostly limited to the year of application. Plant communities differed in all 5 years, with CSP acting as the primary factor for years 2–5. Early seral communities were favored by CSP, but broadcast HWC suppressed resulting herbaceous plants. Though CSP may somewhat reduce stand-level plant diversity, it may increase overall biodiversity within plantation-dominated landscapes by creating early succession plant communities that enhance wildlife habitat.

Dissolved and particulate phosphorus concentration and export patterns in headwater streams draining Boreal Plain watersheds one year after experimental forest harvest and post-harvest silvicultural activities

This study examined total dissolved (TDP) and particulate phosphorus (PP) concentration and export in nine headwater streams draining Boreal Plain forests in Alberta, Canada, during the growing season and autumn before and in the first year after winter harvest in four of the watersheds. Mechanical and chemical site preparation was also conducted before and during the post-harvest sampling period. During the growing season, TDP and PP concentrations in streams draining harvested watersheds were higher than in the reference streams at storm peaks (P ≤ 0.08) and along the falling limbs of storm flows (P ≤ 0.03). We postulate that forestry activities enhanced TDP leaching from watershed soils after they became saturated. This promoted the growth of periphyton in streams, which subsequently sloughed off during high flows. In autumn, TDP concentrations were higher in streams draining harvested watersheds along the rising limb, at the storm peaks, and along the falling limbs (P ≤ 0.05). However, PP concentrations in autumn were similar in harvested and reference streams along the rising limb (P = 0.19) and were lower in harvested streams at the storm peaks and along the falling limbs (P ≤ 0.08). No differences in TDP or PP concentration were detected between harvested and reference streams during baseflow-dominated periods. Mean TDP and PP export coefficients tended to be higher in the post-harvest than pre-harvest year in both reference and harvested watersheds. After normalization to precipitation inputs, this change (“impact ratio”) was 153% and 130% higher in harvested than reference watersheds for TDP and PP, respectively (P ≤ 0.08). The TDP impact ratio and percent of the watershed area cut were positively related (r2 = 0.95, P = 0.02). A 30 m riparian buffer strip in two harvested watersheds did not appear to reduce the harvest response.

Development of opinion-based generic reforestation regimes and their application in vegetation management and water modelling in the Upper and Lower Foothills of Alberta

The operational forestry practices employed by Millar Western Forest Products Ltd. in the Upper and Lower Foothills of Alberta, Canada integrate a broad range of tools to plan, implement, and manage post-harvest site regeneration of pure and mixedwood boreal forests. Following tree harvesting, mechanical site preparation is often used to improve microsite conditions to promote conifer seedling establishment or natural regeneration. Chemical and mechanical site preparation and stand tending control competing vascular weed species. To meet forest regeneration commitments, incorporating knowledge gained from forestry experimentation, long-term field data and iterative deterministic modelling into modified management approaches is employed to formulate appropriate vegetation management strategies. These strategies consider and balance multiple biodiversity (e.g., habitat supply modelling), physical environmental (e.g., streamflow), and societal (e.g., industrial fibre requirements) needs relative to a regenerated vegetation complex. From this experience and understanding, the Company developed a series of generic establishment regimes (GERs), which prescribe detailed silvicultural activities to achieve site-regenerated vegetation complexes in alignment with higher-level forest management planning. An outcome of the GER formulation was the development of corresponding plant community assembly diagrams (PCADs), which describe vegetation complexity and permit calculation of total biomass relative to the time series of silvicultural activities within each GER. In turn, these allow forest planners to model biological, physical, and societal factors, while taking into consideration specific stand growth trajectories based on impacts of silvicultural activities on vegetation biomass and species composition. The GERs and PCADs help formulate vegetation complexes over time and are used to guide the behaviour of a vegetation growth model used in conjunction with a hydrologic simulation model.