Whole-tree Clearcutting Research Articles

Effects of whole-tree and stem-only clearcutting on forest floor and soil carbon and nutrients in a balsam fir (Abies balsamea (L.) Mill.) and red spruce (Picea rubens Sarg.) dominated ecosystem

Intensive harvesting of forest biomass for bioenergy has the potential to degrade forest soils and productivity if ecosystem carbon and other nutrients are depleted faster than replenished naturally or by management inputs. Climate change mitigation potential associated with bioenergy may be threatened if forest management operations reduce soil carbon stocks. Research reported here was initiated in 1979 to determine the effects of whole-tree harvesting on long-term site productivity and ecosystem carbon and nutrient pools and fluxes in a northeastern North American temperate balsam fir-red spruce forest. A sequence of harvesting and silvicultural treatments were applied from 1981 to 1993 using a paired-watershed experimental design. Treatments included whole-tree clearcutting, stem-only harvesting, simulated by return of chipped or lopped delimbing residue, conifer release by applying herbicide, and pre-commercial thinning and fertilizer application. Quantitative samples of the forest floor were excavated in 2016. Quantitative soil pits were sampled in 2017 to a depth of 50 cm below the forest floor, where possible; the basal till subsoil was sampled to a depth of 100 cm with an auger. Forest floor samples were analyzed for total carbon, nitrogen, phosphorus, potassium, calcium, magnesium and aluminum. Organic and mineral soil layer samples from the quantitative pits were analyzed for pH, short and long-lived soil carbon via 13C cross polarization magic angle spinning (CP-MAS) nuclear magnetic resonance (NMR), total carbon and nitrogen and extractable phosphorus, potassium, calcium, magnesium and aluminum. Forest floor carbon and nitrogen on whole-tree harvested plots 35 years after harvest were about 50% of the amount on the unharvested watershed. Stem-only harvesting partially mitigated the reduction, and gross losses were apparently offset by increases in the mineral soil solum to depth 50 cm, suggesting that downward translocation of soil organic matter was a significant ecosystem process during the 35 years since harvest. Accumulated forest floor and mineral soil stock of total carbon and nitrogen and extractable nutrients to depth 100 cm did not differ significantly between the harvested and unharvested watershed. A corresponding similarity in mineral soil pools of extractable phosphorus and non-acid cations in the two watersheds suggests that inputs from atmospheric deposition, primary and secondary mineral weathering, organic matter mineralization and litterfall balanced exports including leaching and plant uptake. Ecosystem stocks of extractable phosphorus, base cations, and total organic carbon and nitrogen were maintained 35 years after whole-tree harvesting of a primary spruce-fir forest.

Comment on “Long-term decline of sugar maple following forest harvest, Hubbard Brook Experimental Forest, New Hampshire”

Cleavitt et al. (2018, Can. J. For. Res. 48(1): 23–31, doi: 10.1139/cjfr-2017-0233 ) report a lack of sugar maple (Acer saccharum Marsh.) regeneration in Hubbard Brook Experimental Forest (HBEF), Watershed 5 (W5), following whole-tree clearcut harvesting and purport that harvesting-induced soil calcium depletion contributed to regeneration failure of this species. In New England, clearcutting is a silvicultural strategy used to promote less tolerant species, especially birch (Betula spp.; Marquis (1969), Birch Symposium Proceedings, USDA Forest Service; Leak et al. (2014), doi: 10.2737/NRS-GTR-132 ), which is just the outcome that the authors report. While this study reports an impressive, long-term data set, given broad interest in sugar maple and sustainability of forest management practices, we feel that it is critical to more fully explore the role of nutrition on sugar maple dynamics, both prior to and during the experiment, and to more fully review the scientific record on the role of whole-tree clearcutting in nutrient-induced sugar maple dynamics.

Динаміка відновлення чорничників після суцільних рубок головного користування

Лісові екосистеми Житомирського Полісся зазнають постійно зростаючого впливу антропогенних чинників, серед яких значне за обсягами місце займають рубки головного користування. Внаслідок рубок змінюються всі компоненти лісу, зокрема дикорослі ягідники, серед яких найпоширенішим видом у лісах державних лісогосподарських підприємств Житомирського Полісся є чорниця звичайна (14 872 га). Під час рубок головного користування значно пошкоджуються, а згодом частково зникають чорничники внаслідок різкої зміни умов середовища. Процес відновлення є досить тривалим. Динаміку відновлення чорничників проаналізовано за двома важливими показниками – проективне покриття та вегетативна надземна фітомаса чорниці звичайної (Vaccinium myrtillus L.) у материнському фітоценозі та лісових культурах різного віку в умовах вологих соснових суборів Житомирського Полісся. Встановлено, що відновлення чорничників відбувається інтенсивно після змикання соснових культур у віці 6–7 років, проективне покриття чорниці сягає 9,7±0,17 %, закінчуючи середньовіковими насадженнями, в яких зазначений показник сягає 67,9±0,26 %. Наведено аналіз статистичної значущості різниці середніх значень проективного покриття та величини надземної вегетативної фітомаси на одиниці площі чорничників між різними віковими групами лісових культур і материнськими фітоценозами.

Leaching of Dissolved Organic Carbon and Trace Elements After Stem-Only and Whole-Tree Clear-cut on Boreal Peatland

The aim of this work was to study the short-term effect of clear-cut harvest on concentrations of dissolved organic carbon (DOC), B, Al, Zn, Cu, Ni, Cr, Cd and Pb in drainage water from northern peatland catchments in Finland underlain by granitic or black shale bedrock, the latter having higher concentrations of several trace elements, such as Ni and Zn. Stem-only harvest (SOH) or whole-tree harvest (WTH) with stump removal were carried out at coniferous sites. Controls were left unharvested. DOC and trace element concentrations were monitored during one pre-treatment and two post-treatment years. There was no constant increase in the element concentrations. However, there were signs that both SOH and WTH clear-cut harvest on northern peatland catchments increases the concentrations of DOC, B, Al, Zn and Ni in ditchwater in some sites irrespective of the bedrock type. The greatest increases were observed in WTH sites but the study does not allow us to assess the statistical significance of the magnitude of the difference between SOH and WTH. We conclude that the element concentrations in ditchwater depend largely on site characteristics masking the possible effect of harvest.

Logging impacts on the biogeochemistry of boreal forest soils and nutrient export to aquatic systems: A review

Logging disturbances in boreal forest watersheds can alter biogeochemical processes in soils by changing forest composition, plant uptake rates, soil conditions, moisture and temperature regimes, soil microbial activity, and water fluxes. In general, these changes have often led to short-term increases in soil nutrient availability followed by increased mobility and losses by leaching to receiving waters. Among the studies we reviewed, dissolved organic carbon (DOC) exports usually increased after logging, and nitrogen (N) mineralization and nitrification often increased with resulting increased N availability and exports to receiving waters. Similar processes and responses occurred for phosphorus (P), but to a lesser extent than for N. In most cases, base cations were released and exported to receiving waters after logging. Several studies demonstrated that stem-only or partial-harvest logging reduced the impacts on nutrient release and exports in comparison to whole-tree clear-cutting. Despite these logging-induced increases in soil nutrient availability and movement to receiving waters, most studies reported little or no change in soil chemical properties. However, responses to logging were highly variable and often site specific. The likelihood, extent and magnitude of logging impacts on soil nutrient cycling and exports in boreal forest watersheds will be dependent on soil types, stand and site conditions, hydrological connectivity, post-logging weather patterns, and type and timing of harvest activities. Additionally, logging impacts can interact with, and be confounded by, atmospheric pollutant deposition and climate change. Further watershed-level empirical studies and modeling efforts are required to elucidate these interactions, to improve predictive capabilities, and to advance forest management guidelines for sustaining forest soil productivity and limiting nutrient exports.

Effect of conventional and whole-tree clear-cutting on concentrations of some micronutrients in coniferous forest soil and plants

Effect of conventional and whole-tree clear-cutting on concentrations of some micronutrients in coniferous forest soil and plants Increasingly intensive and mechanized clear-cutting may deplete the forest ecosystem of essential nutrients. A clear-cut area near Växjö, southern Sweden, was investigated for changes in Mn, Cu and Zn in soil (NH4NO3 extractable and HNO3 soluble) and wavy hair grass (Deschampsia flexuosa) after conventional (CC) and whole-tree clear-cutting (WTC). The soil samples were mostly iron podzols. The area consisted of four clear-cut sites, respectively 2, 4, 6 and 8 years old, and an uncut forest reference stand. Each of the clear-cuts was split in two parts representing WTC and CC sites. Manganese showed the most definite trends after clear-cutting, exhibiting higher extractable concentrations in Oe, Oa and E horizons (4-8 years after clear-cutting) and B horizons (6-8 years after clear-cutting). The increase of exchangeable Mn in the E (2-8 years) and B (4-8 years) horizons was particularly strong. Zn concentrations tended to fluctuate with time. There was a tendency to higher Mn and Zn concentrations in the humus layer especially 2 years after CC-treatment compared with WTC, whereas the opposite trend was apparent for Cu. Mn, Cu and Zn concentrations decreased in Deschampsia flexuosa 2 years after clear-cutting, possibly due to increased soil pH.

Long-term effects of forest management on nutrient cycling in spruce-fir forests

Nutrient dynamics and soil disturbance have been monitored since 1979 on paired control and intensively managed watersheds in central Maine, USA. The mature spruce-fir stand was harvested by whole-tree clearcutting in 1981. Triclopyr was aerially applied to most of the same watershed 4 years after harvest to control hardwoods competing with conifer regeneration. In 1991, a series of plots on the treated watershed were precommercially thinned to stimulate growth of selected crop trees. Then in 1993, nitrogen fertilizer was applied to a subset of thinned plots to further stimulate crop tree growth. Disturbance induced changes in soil solution chemistry differed by soil drainage class. Soil solution NO 3-N concentrations increased from near zero before harvest to 20 mg/l the second growing season following harvest on moderately well drained soils, more than two times corresponding values observed on somewhat poorly drained soils. Net nutrient losses resulting from harvest were <5% of total capital for the nutrients studied. Nitrate-N concentrations on poorly drained soils did not differ from those on the uncut watershed. This same temporal pattern was repeated following application of triclopyr in 1985, although peak concentrations were not as high as those following harvest. Elevated concentrations of nutrients in soil solution following both harvest and herbicide application disappeared within 3 years, concurrent with regeneration. Precommercial thinning (PCT) reduced stem density approximately 12-fold, increasing crop tree DBH for both balsam fir (4 cm on control plots versus 6 cm on PCT plots) and red spruce (4 cm on control plots versus 5.5 cm on PCT plots). Although 34 Mg/ha of thinning slash remained after PCT (pre-harvest forest floor dry weight averaged 64 Mg/ha), soil solution chemistry was not affected and nutrients were apparently conserved following treatment. Soil solution nitrate and cation concentrations increased following N fertilization. The fertilizer treatment further increased balsam fir DBH (8 cm on fertilized plots) but not red spruce. Soil disturbances associated with harvesting may be problematic. Compaction and rutting from the road system and repeated trips of the feller-forwarder were still highly evident. Much of this area remains out of production and likely will be characterized by poor tree establishment and reduced growth through the current rotation.

Logging in New England Need Not Cause Sedimentation of Streams

Abstract Erosion, sedimentation, and turbidity can be controlled during and after logging in New England forests by conscientiously following regulations and guidelines known as Best Management Practices (BMPs). This is demonstrated by comparing sediment yields and stream turbidities from cut and uncut watersheds at the Hubbard Brook Experimental Forest in central New Hampshire. Sediment yields from uncut forests average about 40 kg/ha/yr, but are highly variable from year to year and from watershed to watershed. Disturbances due to cutting and logging can increase sediment yields. For example, in the first year after a whole-tree clearcut at Hubbard Brook, sediment yields increased 10- to 30-fold over uncut watersheds. However, total yields after cutting and skidding were still small and did not greatly affect stream turbidity. North. J. Appl. For. 11(1): 17-23.

Soil Disturbance Following Whole-Tree Harvesting in North-Central Maine

Abstract Mechanical whole-tree harvesting can reduce site productivity if it results in excessive soil disturbance, which may both kill advanced regeneration and reduce the potential of the soil to support tree growth. Large feller-forwarders with wide, high flotation tires were designed to reduce soil disturbance, but they can cause excessive amounts of site disturbance if harvesting is conducted when soils are wet. The spatial distribution and severity of soil disturbance were determined on line transects after a spring whole-tree clearcut in northern Maine on the silt loam soils of the Chesuncook catena. Exposed mineral soil and deep wheel ruts occurred more frequently on somewhat poorly (37% of surface area) and poorly (42%) drained soil than on moderately well-drained soil (19%). This amount of site disturbance seems excessive and could reduce future site productivity due to removal of organic horizons and destruction of advanced conifer regeneration. Harvesting with large feller-forwarders on the poorly and somewhat poorly drained silt loam soils of this region should be discouraged in the spring and possibly during other periods of high soil water tables. North. J. Appl. For 8(2):68-72.

Whole-Tree Clear-Cutting Effects on Exchangeable Cations and Soil Acidity

Whole-Tree Clear-Cutting Effects on Exchangeable Cations and Soil Acidity

Whole-Tree Clear-Cutting Effects on Soil Horizons and Organic-Matter Pools

Timber harvest results in physical disturbance and relocation of soil materials. This study was undertaken to assess the degree to which logging altered soil horizonation, bulk density, and organic-matter pools at a northern hardwood forest site underlain by Spodosols. Soils were sampled immediately before and 3 yr after the commercial whole-tree harvest of Watershed 5 at the Hubbard Brook Exerpimental Forest in central New Hampshire. The activity of logging machinery resulted in redistribution of organic matter within the solum. Thus, the thickness of the O horizon decreased from 6.9 cm to 5.5 cm, while O horizon mass and organic-matter content increased (from 8.7–12.2 kg m−2 and from 5.4–5.7 kg m−2, respectively). One-fourth of the postharvest soil pits exhibited an Ap horizon, which was not present prior to harvesting and was formed from soil of the O, E, and Bh horizons. Compaction of the soil during the logging operation resulted in increased (5–15%) bulk density in the upper 20 cm of mineral soil. The total pool of organic matter in the solum did not change following harvesting. Thus, losses of organic matter via streamwater and respiration were approximately balanced by inputs from decaying roots and leaf litter. The conservation of organic matter following harvesting is important in preserving soil fertility, since labile nutrients in northeastern Spodosols are generally associated with organic matter.

Effects of intensive harvesting on nutrient capitals of three forest types in New England

Effects of whole-tree clearcutting are being studied in three major forest types in the northeastern United States: a spruce-fir forest in central Maine, a northern hardwood forest in New Hampshire, and a central hardwood forest in Connecticut. At each site we sampled total and extractable nutrient capitals, inputs and outputs of nutrient ions in precipitation and streamflow, nutrient removals in harvested products, and nutrient accumulation in regrowth. Depending upon location, combined losses of nutrients in harvested products and increased leaching to streams were in the ranges of 374–558 kg ha −1 for Ca, 135–253 kg ha −1 for K, 50–65 kg ha −1 for Mg, 248–379 kg ha −1 for N, and 19–54 kg ha −1 for P. Opportunities for replacing these losses over the next rotation are best for N. Data on inputs in precipitation versus outputs in streamflow indicate that, once effects of harvest subside, most N in precipitation will stay within the forest. By contrast, Ca shows a net output of 8–15 kg ha −1 year −1 from uncut watersheds, and the added leaching losses due to harvest may have a serious impact on Ca capital. This is especially the case for the Connecticut site, where total site capital for Ca is only about 4000 kg ha −1.

Biomass and nutrient removals from commercial thinning and whole-tree clearcutting of central hardwoods

Biomass and nutrient removals from commercial thinning and whole-tree clearcutting of central hardwoods

Biomass and nutrient removals from commercial thinning and whole-tree clearcutting of central hardwoods

The objective of this research was to evaluate the impacts of increasing product removal on biomass and nutrient content of a central hardwood forest ecosystem. Commercial thinning, currently the most common harvesting practice in southern New England, was compared with whole-tree clearcutting or maximum aboveground utilization. Using a paired-watershed approach, we studied three adjacent, first-order streams in Connecticut. During the winter of 1981–82, one was whole-tree clearcut, one was commercially thinned, and one was designated as the untreated reference. Before treatment, living and dead biomass and soil on the whole-tree clearcut site contained 578 Mg ha−1 organic matter, 5 Mg ha−1 nitrogen, 1 Mg ha−1 phosphorus, 5 Mg ha−1 potassium, 4 Mg ha−1 calcium, and 13 Mg ha−1 magnesium. An estimated 158 Mg ha−1 (27% of total organic matter) were removed during the whole-tree harvest. Calcium appeared to be the nutrient most susceptible to depletion with 13% of total site Ca removed in whole-tree clearcut products. In contrast, only 4% (16 Mg ha−1) of the total organic matter and ⩽2% of the total nutrients were removed from the thinned site. Partial cuts appear to be a reliable management option, in general, for minimizing nutrient depletion and maximizing long-term productivity of central hardwood sites. Additional data are needed to evaluate the long-term impacts of more intensive harvests.

Biomass and nutrient removals by conventional and whole-tree clear-cutting of a red spruce – balsam fir stand in central Nova Scotia

Data are presented of biomass and nutrient removals by conventional and whole-tree clear-cutting of 0.5-ha blocks of an all-aged Picearubens – Abiesbalsamea stand in central Nova Scotia. The biomass yield from the conventional clear-cut plot was 105 200 kg dry weight•ha−1, and the removals of N, P, K, Ca, and Mg were 98.2, 16.3, 91.7, 180.9, and 17.0 kg•ha−1 respectively. Biomass removals from the whole-tree clear-cut plot were 152 500 kg dry weight•ha−1, and the removals of N, P, K, Ca, and Mg were 239.1, 35.2, 132.6, 336.5, and 36.9 kg•ha−1, respectively. These removals of N, P, K, Ca, and Mg from the whole-tree harvested plot, expressed as percentages of the quantities of these nutrients in the "total" pool within the exploitable soil horizons, were 5.0, 2.8, 1.0, 5.9, and 2.1%, respectively. However, when these removals were expressed relative to the quantities in the "available" soil pools, they were much larger, i.e., 500, 34, 184, 306, and 95% for N, P, K, Ca, and Mg, respectively.