Whole-tree Harvesting Research Articles

Biomass production and nutritional efficiency in short rotation eucalypt clone plantations for energy in north-east Brazil

Selecting adapted hybrids with greater efficiency in the use and return of nutrients is essential to ensure the success of forestry activities. Although topics on the nutritional sustainability of eucalypt biomass harvesting have frequently been discussed, few studies have focused on short rotation eucalypt clonal plantations (aimed at energy production), especially in conditions of nutrient scarcity and water limitations in Brazil. Therefore, our objective was to evaluate the nutritional efficiency and sustainability (for nitrogen (N), phosphorus (P) and potassium (K)) of six eucalypt clones in short rotation cultivation in the north-east of Brazil, considering different harvesting scenarios and using the Eucalyptus urophylla species as a reference, which is traditionally planted in the study region. Direct quantification of the biomass of 21 trees of each clone was carried out at 5 years of age. The clones did not affect the accumulation of total biomass (on average, 199.9 Mg ha−1). The 1296 and 1355 clones provided lower biomass export and greater nutritional efficiency, favouring an increase in the potential number of rotations (PNR) for P and a reduction in the N removal rate (RR). However, the VM58 clone showed higher biomass export and lower PNR. Thus, clones 1296 and 1355 are more favourable, while clone VM58 is less favourable to nutritional sustainability under the studied conditions. Nitrogen and K may cause productivity limitations in future rotations in whole-tree harvesting systems. Adopting more conservationist harvesting systems with removing only the stemwood or stemwood with bark can optimise the potential of clones, minimise the need to add fertilisers and ensure maintenance of the site’s productivity.

Nutrient pools and loss due to the removal of harvesting residue in cedar plantations (a case study from Türkiye).

Determining the nutrient stocks and revealing the extent to which these stocks will be affected by the interventions in forest ecosystems are crucial for sustainable forest management. This study aimed to determine the nutrient stock of cedar (Cedrus libani A. Rich.) plantations at different stands with various diameter classes and estimate the nutrient stock to be removed from the forest due to harvesting. Soil and plant samples were collected from 40 plots in Eskişehir and Afyonkarahisar provinces in Turkey. The variation in the nutrient concentrations and stocks of different components of the ecosystem were evaluated by analysis of variance and the decrease via harvesting by regression analysis. The results showed that the concentrations of N, P, K, Mg, S, Fe, Zn, and Mn were highest in the needles, Ca in the bark, Cu in the needles, dead branches, and root. In the large-diameter forest (LDF), dbh=20.0-35.9 cm, the highest P stock was found in the trees, Fe stock in the forest floor, and S stock in the soil and trees. As a result, the forest floor should be protected as it is the crucial component of both the nutrient cycle and the Fe stock in the ecosystem. In LDF, 28.4-37.3% of the nutrient stored in the trees would be removed from the ecosystem in the case of moderate thinning with whole-tree harvesting, while only 5.9-14.1% of the nutrient stock in the case of stem-only harvesting. For these reasons, leaving logging residues after harvesting in the forest would minimize nutrient loss. The study results showed that improved nutrient management in a forest ecosystem will make a significant contribution to the sustainability of forests.

Soil Texture Explains Soil Sensitivity to C and N Losses from Whole-Tree Harvesting in the Boreal Forest

The use of forest biomass to produce energy is increasingly viewed as a means to reduce fossil fuel consumption and mitigate global warming. However, the impact of such practices on soils in the long term is not well known. We revisited forest plots that were subjected to either whole-tree (WTH, n = 86) or stem-only (SOH, n = 110) harvesting 30 years ago in the boreal forest in Quebec, Canada. The objective of the present study was to find soil properties that could explain the lower soil C and N stocks at the sites subjected to WTH compared to SOH after 30 years. Compared to SOH, lower soil C and N stocks attributable to WTH occurred when soil particle content <20 µm was below 30%. The theoretical separation of soil organic matter into two fractions according to soil particle content <20 µm—a recalcitrant and a labile fraction—could explain the observed pattern of soil C and N differences between WTH and SOH. Imperfect or poor soil drainage conditions were also associated with lower soil C and N in WTH compared to SOH. Limiting additional biomass harvesting from these sites would help to preserve soil C and N from potential losses.

Harvest Intensity Impacts Nutrient Status and Young Stand Development in Latvian Hemiboreal Forest

This study aimed to compare the effects of whole-tree and stem-only harvesting in hemiboreal forests in Latvia. Chemistry of soil solution, precipitation, litter and needles, as well as tree parameters in regenerated stands were measured from 2012 to 2021 in oligotrophic and mesotrophic Scots pine sites with mineral soils and a eutrophic Norway spruce site with drained peat soil. Compared to the undisturbed control, the soil solution pH was significantly lower and N-NO3− and K+ concentrations were significantly higher after stem-only harvesting at the oligotrophic site, stem-only and whole-tree harvesting at the mesotrophic site and whole-tree harvesting at the eutrophic site. The height growth of the regenerated stands in all sites was similar for both harvesting methods six years after planting. More slender trees were observed after whole-tree harvesting than after stem-only harvesting at the eutrophic site. Whole-tree harvesting produced significant negative short-term effects on height growth in the oligotrophic site four to six years after harvest. The nutrient levels of needles differed with harvest intensity but did not indicate insufficient nutrient availability with any type of harvesting.

Productivity and cost assessment of two harvesting methods for medium-rotation poplar plantations

ABSTRACT The study compared the cut-to-length (CTL) and the whole-tree-harvesting (WTH) methods under two alternative log length specifications (2 m vs. 4 m) as deployed in the new medium-rotation poplar plantations. The goal of this study was to determine if any of the four combinations of harvesting method and log length incurred lower cost and/or better log yield than the others. The test was conducted in a 6-year-old plantation with a stocking between 30 and 60 bone-dry tons (BDT) per hectare. Each treatment was repeated 8 times – each repetition consisting of one sample plot with a 700 m2 surface area (115–130 trees). Researchers determined the mass obtained from each sample plot, as well as the time necessary to turn standing trees into logs and biomass piled at the landing. A calculator was developed for estimating harvesting costs as a function of variable machine rates. Under the conditions of the study, CTL harvesting into 4-m long logs was the most effective solution, because it offered a better log yield compared with WTH (60% vs. 50%) and incurred the same harvesting cost (∼ 33 € BDT−1). Shortening log length to 2 m determined a 25% increase of harvesting cost.

The sustainability of timber and biomass harvest in perspective of forest nutrient uptake and nutrient stocks

The sustainability of tree harvest is questioned since harvest results in increased nutrient losses which may reduce nutrient stocks in forest soils, particularly in forests on acidified and poor soils with low base saturation. We used a new forest experiment to quantify nutrient stocks and nutrient uptake rates in mature forest stands, and to assess the forest nutrient balance in relation to different forest management scenarios: clearcutting, shelterwood and thinning; and whole-tree harvest (WTH), stem-only harvest (SOH) and wood only harvest (WOH, with on-site bark stripping). Forests were dominated by trees of Fagus sylvatica, Pseudotsuga Menziesii or Pinus sylvestris, all situated on poor, acidified soils.We measured forest biomass and nutrient stocks based on destructive sampling of fifteen mature trees per species and by using new, calibrated allometric relationships. Aboveground stocks of N, P, S, K, Ca, Mg, Mn, Cu, Fe and Zn were calculated for foliage, branches, stem bark and stem wood. Annual forest growth and nutrient uptake were determined using tree ring measures and allometric relationships. Organic layer nutrient stocks and available nutrients in the mineral soil were determined following intensive soil sampling.Stands of beech, Douglas fir and Scots pine differed in aboveground biomass and nutrient stocks, with highest biomass stocks in Douglas fir. However, beech stands had the highest aboveground nutrient stocks, nutrient uptake rates and nutrient losses following harvest, followed by Scots pine. Organic layer nutrient stocks generally exceeded aboveground nutrient stocks, except for the base cations and Mn. Compared to SOH, WTH increased nutrient export between 66% (Douglas fir) up to 100% (Scots pine), while WOH decreased the nutrient export between 23% (beech) up to 41% (Douglas fir).High aboveground base cation and Mn stocks indicate potential long-term threats to forest nutrition if trees are harvested. However, in Douglas fir stands, nutrient losses through SOH may fully recover when using rotation periods of 80 years. Contrary, negative Ca balances are predicted when applying SOH in beech and Scots pine, since Ca stocks are potentially depleted within 2 final fellings. WTH poses, regardless of the species, potential threats for sustainable biomass harvest as nutrients cannot be recovered using common rotation periods. WOH conserves nutrients within the forest posing opportunities for sustainable biomass harvest. For similar temperate forest on acidified, sandy soils, we therefore recommend to limit tree harvest depending on the tree species, and to avoid WTH and consider WOH to better conserve critical nutrients required for long-term forest recovery.

Weathering rates of Ca and Mg related to granitic and gabbro mineralogy in boreal forest soils and the effect of mechanical soil disturbance on weathering release

This study’s aim was to calculate the weathering rates of Ca and Mg for five boreal forest soils in southern Finland on granitic and gabbro containing bedrock. The effect of mineralogy on the total concentrations of Ca and Mg in soil and weathering rates was evaluated. The aim was also to estimate the effect of mechanical soil disturbance related to ploughing on the weathering in the gabbro area. The total concentrations of SiO2, CaO, MgO, and Zr were determined by XRF, and weathering rates of Ca and Mg were determined based on the changes in the CaO, MgO, and Zr concentrations. The weathering rates of Ca+Mg varied 5–38 mmolc m–2 year–1 in the E+B/BC horizons among the plots. Soil disturbance related to ploughing increased the weathering of Ca and Mg largely in the disturbed part of the topmost mineral soil as indicated by the decreasing concentrations of Ca and Mg after mechanical soil disturbance. The weathering input of Ca in the undisturbed soil did not fully replace the Ca output in final whole-tree cutting. The weathering input of Mg in the undisturbed soil was sufficient to replace the lost Mg in stemwood harvesting but not on all the plots the lost Mg in whole-tree harvesting. Weathering rates were higher in the gabbro than the granitic areas.

Changes in ecosystem nutrient pools through stand development following whole-tree harvesting of jack pine (Pinus banksiana) on sandy, nutrient poor soils in northern Lower Michigan

We used a 10-site, 42-year chronosequence of jack pine (Pinus banksiana) plantations to study the changes in ecosystem nutrient pools following whole-tree harvesting (WTH) on sandy soils. We developed locally-derived allometric equations to predict nutrient contents of jack pine as a function of diameter at breast height and used these to estimate the amount of nitrogen (N), calcium (Ca), potassium (K), magnesium (Mg), and phosphorus (P) stored in aboveground biomass. In addition, we quantified total N, Ca, K, Mg and P in surface organic horizons, plant-available nutrient pools in mineral soils and leaching losses of nutrients for four years post harvest. Finally, we constructed simple input–output nutrient balances accounting for harvest removals at varying ages, post-harvest leaching losses and nutrient inputs from atmospheric deposition and weathering under varying scenarios of harvest intensity and frequency. Nutrient accumulation in aboveground biomass followed a sigmoidal pattern with a period of rapid accumulation between ages 10–20 y, a period of slowing accumulation between 20 and 30 y to an apparent asymptote from 30 y onward. Our estimates of asymptotic aboveground nutrient stocks for these plantations were highest for N (263 kg ha−1), intermediate for K and Ca (112 and 95 kg ha−1) and lowest for Mg and P (22 and 17 kg ha−1). Nutrients in forest floor materials increased from our youngest stand (4 y post harvest) with no signs of slowing accumulation in older stands. We observed weak trends of increasing soil nutrient availability across our chronosequence; however, variability was high both within and among stands. The business-as-usual scenario of WTH and planting on a 50-y rotation had a positive input–output balance for all nutrients with the exception of K, where outputs over this rotation exceeded inputs by 54 kg K ha−1. Shifting to a bole-only harvest improved the nutrient balance for all elements considered and shifted K to a net positive balance of 32 kg K ha−1. Scenarios designed to maximize production of biomass energy with WTH on shorter rotations exacerbated the K imbalance, with net losses of 72 and 63 kg K ha−1 for 30- and 20-y rotations, respectively.

The Impact of Integrated Harvesting Systems on Productivity, Costs, and Amount of Logging Residue in the Clear-Cutting of a Larix kaempferi (Lamb.) Carr. Stand

Two integrated harvesting methods have been primarily applied to increase the opportunity for forest biomass utilization. In Korea, small shovels with a carrier for cut-to-length harvesting (CTL system) and tower yarders for whole-tree harvesting (WT system) are commonly used for the transportation of tree assortments (i.e., sawlogs and logging residue). No previous studies are available in South Korea that have compared and highlighted the operational performance and yield of logging residues between the CTL and WT harvesting systems. Thus, our study’s main objectives were to (1) evaluate the productivity and costs of the two harvesting systems through a standard time study method and (2) estimate the amount of harvesting logging residue at the landing. The productivities of the CTL and WT systems were 1.45 and 2.99 oven-dried tons (odt)/productive machine hour (PMH), at a cost of 86.81 and 45.41 USD/odt, respectively. In the WT system, the amount of logging residue (2.1 odt/ha) collected at the landing was approximately four-times larger than that of the CTL system (0.5 odt/ha). Our results suggested that the WT system is a less expensive and more suitable system when there are markets demanding logs and biomass, whereas the CTL system remains a less expensive option for stem-only harvesting. Furthermore, these results are important for estimating the economic and environmental amount of residue that could be potentially recovered and utilized from the forest types included in the study.

Integrated Harvesting of Medium Rotation Hybrid Poplar Plantations: Systems Compared

In this study, the authors provide a direct comparison made between whole tree-harvesting (WTH) and cut-to length (CTL) methods, which was conducted in two sites in the Slovak Republic and applied to poplar plantations. Both systems, WTH and CTL, have been employed at the highest mechanization level in two sites: “Nivky” and “Skalica”. Two different strategies, namely, “mass handling” and “small-scale mechanization”, have been used for WTH and CTL, respectively. The study results showed that the level of productivity (ODT SMH−1) in the felling operation was almost double for WTH than for the CTL method in Nivky (+84%) and more than double in Skalica (+113%). The extraction operation under WTH showed a productivity increase from one fifth (+20%) to more than double (104%) that of the CTL method in the Nivky and Skalica sites, respectively. Regarding cost-efficiency (EUR ODT−1), the WTH system offers a similar trend except with respect to extraction in Nivky (higher productivity site), in which the CTL extraction was 4.5% less expensive than the WTH extraction. The study results show that the mass-handling technique deployed in the WTH system offers very good performance in poorer plantations since the very small tree size and low-growing stock challenge the CTL system more than the WTH system. The total operation (felling, bucking, and extraction) costs (EUR ODT−1) recorded by the study in commercial conditions (as contractors perform for revenue purposes) were 32.50 and 45.80 EUR ODT−1 for CTL and 43.30 and 53.60 EUR ODT−1 for WTH for the higher-yield site (Nivky) and lower-yield site (Skalica), respectively. Regarding the WTH System, the researchers found that the drop in efficiency (and the consequent rise in the costs-per-ton of product) depends largely on the bucking phase conducted using the harvester at the landing of the stacked piles of interlocked trees. The main results of this study demonstrate the promising strategy of mass handling associated with the WTH system in medium rotation coppice (MRC) harvesting and shows that bucking is the weaker phase. Future efforts must be made to ensure feasibility of the “mass handling” strategy alongside the entire workflow by means of finding suitable mobile machinery that can delimb, debark, and crosscut tree bunches instead of single trees.

Whole-Tree Harvest Effects on Macronutrients in an Oak-Dominated System after Seven Years

This study assesses the impacts of whole-tree harvesting (WTH) versus stem-only harvest (SOH) on two oak-dominated stands located in Northern Wisconsin. Specifically, our study follows up on an experiment designed to better understand the impacts of WTH and whether stands are at risk of long-term nutrient losses, which could contribute to declines in productivity. The original study assessed: (i) full biomass removal (referred to as WTH), (ii) partial biomass removal (removal to 5 cm diameter bole), (iii) a traditional SOH (removal to 10 cm bole), and (iv) no harvest (control). Our data were collected 93 months after harvest and showed significant decreases (α = 0.05) in the total (soil, woody debris, litter, and tree) Ca between WTH and SOH and for N and K from all harvest types. P and Mg were not significantly different between any of the treatment types. The woody debris was significantly decreased in the WTH in comparison to the SOH across P, K, Ca, Mg, but not N. The differences in the woody debris were initially detected, but a nutrient budget modeling exercise did not show significant declines for the ecosystem. The nutrient budget model assumptions and scale of input terms are discussed. Revisiting the sites at 93 months post-harvest versus the original 1.75 years allowed for the detection of the differences in total N, K, and Ca pool sizes.

Wildfire loss of forest soil C and N: Do pre-fire treatments make a difference?

Losses of C and N from the forest floor and top 20-cm of soil were estimated following separate severe wildfires at two Long-Term Soil Productivity sites in the Sierra Nevada of California, USA. Experimental treatments applied 20 years prior to the wildfires included factorial combinations of 1) organic matter (OM) removal following clear-cut harvesting (SO, stem only harvest, WTH, whole-tree harvest, and WTH + FF, WTH plus the forest floor removal), 2) soil compaction (three levels of intensity), and 3) with and without understory vegetation control. Wildfires caused complete losses of the forest floor in all treatments and also oxidized varying portions of OM in the topsoil. As such, pre-fire forest floor measures were used as an estimate of forest floor C and N loss, and post-fire soil measures of C and N were compared to pre-fire soil data to estimate of mineral soil losses. Averaged over all treatments, the less-productive site that also had lesser accumulations of detritus (Wallace) lost 35.1 Mg C ha−1, or 25 % of its original C stores, while the more-productive site with greater detritus (Rogers) lost 18.4 Mg C ha−1, or 20 % of its original. The SO treatments that left harvest residue on site ended up with much greater losses of C: 36 % versus 15 and 17 % for WTH and WTH + FF, respectively. The SO also yielded the largest losses (25–30 %) of C in the top 10-cm of soil. The other treatments had smaller or inconsistent effects (understory vegetation control) or no effect (soil compaction). Our results suggest that potential benefits from SO by leaving residue on site to soil C and N accumulation can also be readily eliminated by wildfire which commonly occurs at these fire-prone forest ecosystems.

Response of soil and vegetation in a warm-temperate Pine forest to intensive biomass harvests, phosphorus fertilisation, and wood ash application

The objective of this study was to assess the effects of different intensities of biomass harvesting, and the possible effects of compensation methods, on forest functioning. To do so, we carried out a split-plot experiment (SW France) crossing four different intensities of biomass harvesting (Stem-Only Harvest [SOH], Aboveground Additional Harvest [AAH], Belowground Additional Harvest [BAH], and Whole-Tree Harvest [WTH]) and three compensation methods (control [C], wood ash application [A] and phosphorus fertilisation [P]). The experimental treatments were followed by the plantation of pines (Pinus pinaster). The environmental consequences of treatments on soil and vegetation were evaluated 11 years after the tree plantation.Despite their low additional biomass exports (+10 % for AAH to +34 % for WTH), the non-conventional harvest practices exported much higher quantities of nutrients than the conventional SOH technique (+145 % of exported N in WTH). Additional biomass harvests impacted the soil organic matter content, with negative effects on P-organic, soil cation exchange capacity, exchangeable Ca, and most extractible nutrients. However, tree nutritional status was improved by P-fertiliser or wood ash. We observed a positive effect of wood ash application on soil pH and nutrient content but, like additional harvests, wood ash application decreased the pool of soil organic carbon (~10 %).Overall, the experiment showed that exporting more forest biomass due to the additional harvesting of biomass had negative consequences on the ecosystem biogeochemistry. Additional harvests have impoverished the soil, and decreased the soil organic carbon content. Importantly, applying nutrients as fertiliser or wood ash did not compensate for all the negative impacts of biomass exports and the method of wood ash recycling in forests could even decrease the soil organic carbon.

A cost-benefit analysis of pre-sorting using a feller-buncher in underdeveloped short rotation poplar plantations

ABSTRACT Underdeveloped tree crops (⩽ 30 bone-dry tons ha−1) offer a main harvest of biomass-trees, which lack the size and the form for producing a log. However, about 1/3 of the available stems may yield at least one log, which could significantly increase the overall value of the harvest. Under those circumstances, it may make sense to sort log-trees from biomass-trees at an early stage, rather than having a harvester or a processor go through all of the treesonly to toss almost 70 out of 100 trees into the biomass pile. The Authors set up a controlled experiment to quantify the eventual benefit obtained by early pre-sorting, performed by the feller-buncher. Pre-sorting resulted in a 15% productivity loss for the feller-buncher, which was repaid by a 100% productivity increase for the processor. Considering the different hourly cost of the two machines, three Euros were saved for each additional Euro invested in pre-sorting. Pre-sorting made whole-tree harvesting (WTH) a significantly cheaper option than cut-to-length (CTL) , whereas the two systems would be almost equally expensive when no pre-sorting was applied. Pre-sorting would also facilitate multiple-tree delimbing, implemented through the introduction of a chainflail; that is likely to further reduce harvesting cost, returning financial viability to the harvesting of underdeveloped plantations.

The Impact of Clear-Cutting on the Volume and Chemistry of Water at a Sandy Nutrient-Poor Pine Site

Clear-cutting removes a stand cover suddenly, thus impacting soil-surface conditions by the expected increase in the humus breakdown rate, due to the addition of more precipitation and solar radiation. The impacts of removing a forest were studied at a site with deep sandy soils dominated by Scots pine, where three treatments, including a stand left on site, whole-tree harvesting treatment, and stem-only harvesting treatment, were established. Clear-cut precipitation and sub-canopy throughfall were measured. The non-replicated treatments were equipped with lysimeters at depths of −10 cm and −70 cm and in addition, three exploratory wells were drilled to sample groundwater in each of the treatments. The volume and chemistry of the water samples were periodically analyzed. The mean throughfall was 84% of open-area precipitation and the pH of the water penetrating the canopy was significantly lower overall, although the subcanopy samples were only slightly more acidic. Significant differences among the treatments were shown in throughfall (total organic carbon, TOC), shallow subsurface water (pH, TOC, NO3−), subsurface water at the 70-cm depth (NO3−) and also groundwater (pH, TOC, NO3−), where some of the differences had been observed before the stand parts were clear-cut. Limits for drinking water were exceeded in groundwater pH, as the values from both clear-cut sites fell below pH 6.5 following clear-cutting. TOC greater than 5 mg·L−1 was found in the Q1-2020 samples, whereas groundwater nitrate remained low, even though the three wells differed significantly from each other. Due to the non-replicated design of the experiment, generalization of the outcomes is a matter of further research.

Impacts of harvesting methods on nutrient removal in Dutch forests exposed to high-nitrogen deposition

ContextForest harvest removal may cause nutrient depletion of soils, when removal of essential nutrients, including nitrogen (N), phosphorus (P), sulphur (S), calcium (Ca), potassium (K) and magnesium (Mg) exceeds their net input by deposition and weImpacts of acid atmospheric deposition on woodland athering minus leaching. Nutrient removal by harvest depends on tree species and the harvesting method, i.e. whole-tree harvesting (removal of stems and branches) versus stem wood removal only.AimThe aim of this study was to assess the impacts of these two harvesting methods on nutrient removal in Dutch forests exposed to high-nitrogen deposition.MethodsTo assess those impacts, we measured nutrient concentrations in stem wood and branch wood of seven major tree species in the Netherlands, i.e. Japanese larch (Larix kaempferi Lamb.), Norway spruce (Picea abies L. Karst.), Douglas fir (Pseudotsuga menziesii Mirb.), Scots pine (Pinus sylvestris L.), silver birch (Betula pendula Roth), beech (Fagus sylvatica L.) and common oak (Quercus robur L.). Average nutrient concentrations in stems were based on measured concentrations in heartwood, sapwood and bark and estimated volumes and densities of these compartments. Similarly, average nutrient concentrations in branches were based on measured concentrations in coarse branches, fine branches and the bark of coarse branches and estimated volumes and densities of these compartments. Removal was assessed by using the average growth rates of these tree species on nutrient poor sandy soils in the Netherlands.ResultsCompared to other countries, N concentrations in the Netherlands were higher in stems, while phosphorus, Ca, K and Mg concentrations in both stems and branches were nearly always lower. The elevated long-term N deposition levels in the Netherlands most likely contribute to this finding, since N deposition causes soil acidification reducing the availability of Ca, K, Mg and P, that could become limiting to growth. Limits for sustainable harvest, above which outputs exceed inputs of nutrients, depend on nutrient, soil type and tree species and are mostly determined by K and P and sometimes Ca, which may already be depleted at relatively low harvest levels on poor sandy soils, in particular for broadleaved species, while depletion of Mg is not likely. Nevertheless, the average growth of forests in the Netherlands appears to be slightly higher than in most other countries in Europe.ConclusionOverall, we thus conclude that limited P, Ca, Mg and K availability in response to elevated N deposition is reflected in reduced contents of these nutrients in stem wood and branch wood but not in growth.Key messageNutrient concentrations in tree compartments were assessed for seven major tree species in the Netherlands. Concentrations of phosphorus, calcium, potassium and magnesium (base cations) in stems and branches are mostly lower compared to those in other countries, while nitrogen concentrations are higher. A long-term nitrogen deposition has likely contributed to these differences. The average growth has not declined, despite the low availability of phosphorus and base cations. Limiting the harvest of branch wood is suggested on nutrient poor soils to avoid depletion of phosphorus and base cations.

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.

Contrasting dynamics and factor controls in leaf compared with different-diameter fine root litter decomposition in secondary forests in the Qinling Mountains after 5 years of whole-tree harvesting

Plant litter decomposition is a crucial pathway for carbon (C) and nutrient cycling, and controls the net primary productivity in ecosystems worldwide. However, little is known about how multi-type litter (leaf and different diameter fine roots) decomposition rates and nutrient release change at the community level following whole-tree harvesting (WTH). In the present study, we followed decomposition of leaf and different diameter fine root (∅ < 0.5 mm, 0.5–1 mm, 1–2 mm) litters at plot level over 2 years in a secondary forest in the Qinling Mountains after 5 years of five different thinning treatments (0%, 15%, 30%, 45%, and 60%). Our results demonstrated that WTH had no effects on leaf and different diameter fine root litter decomposition at the plot level. Leaves had significantly higher decomposition rate than different diameter fine roots. There were significant positive correlations between decomposition rate of different diameter fine roots, but not related to leaf litter decomposition rate. WTH did not affect the nutrient release of leaf and different diameter fine root litters at the plot level. The nitrogen (N), phosphorous (P) and potassium (K) mass remaining in leaf litters were significantly higher than different diameter fine roots after 2 years decomposition, while different diameter fine roots had higher C mass remaining. Leaf and fine root litter decomposition rates were mainly influenced by stand and litter quality attributes. Nutrient release of leaf and fine root N, P and K were mainly predicted by litter quality characteristics, while there were no consistent driving factors for C release. Our results suggested that WTH had no effects on multi-type litter decomposition and nutrient release at plot level after 5 years of recovery. Moreover, leaf litters had excellent N, P and K nutrient preservation mechanisms, and C conservation in fine root litters.

Whole-Tree Harvest Effects on Macronutrients in an Oak-Dominated System after Seven Years

Whole-Tree Harvest Effects on Macronutrients in an Oak-Dominated System after Seven Years

Whole-tree harvest effects on soil macronutrients in an oak-dominated system after seven years

Whole-tree harvest effects on soil macronutrients in an oak-dominated system after seven years