Red Pine Stands Research Articles

Impacts of bamboo invasion on soil macro- and micronutrients in temperate red pine stands

Impacts of bamboo invasion on soil macro- and micronutrients in temperate red pine stands

Genç Kızılçam Biyokütle Denklemleri; Kozağacı Orman İşletme Şefliği Örneği

Ormanların karbon depolama kapasitelerine ilişkin hesaplamalar tüm dünyada giderek daha önemli hale gelmiştir. Karbon bildirimlerinde uluslararası kurumlar, orman ekosistemlerinde depolanan karbon miktarlarının envantere dayalı olarak, tam ve kesin olarak belirlenmesini arzu etmektedir. Tüm ülkenin ormanlık alanlarındaki karbon stokunun belirlenmesi için, her ağaç türünün farklı habitatlarda biriktirdiği biyokütle miktarının ve bağladıkları karbon miktarının yöresel olarak belirlenmesi gerekmektedir. Bu çalışmada genç kızılçamlar yöresel olarak dikkate alınarak, Mersin Kozağacı Orman İşletme Şefliği içerisindeki saf kızılçam meşcerelerine ait toprak üstü ve toprak altı biyokütle denklemleri geliştirilmiştir. Çalışmada ayrıca kızılçam için odun yoğunluk oranı ve ibre kuru ağırlık oranı belirlenmiştir.

Comparative detection, density, and reproductive performance of Kirtland's warbler in jack and red pine

AbstractThe formerly endangered Kirtland's warbler (Setophaga kirtlandii) is among a growing number of conservation‐reliant species that depend on active management to avoid reverting to endangered status. Because the Kirtland's warbler is a habitat specialist of young, even‐aged jack pine (Pinus banksiana), managers of the recovery effort stressed creating new jack pine stands and monitoring numbers of singing males through an annual census using single visits to individual stands. Kirtland's warbler will occupy and breed in red pine (P. resinosa), but red pine has not been surveyed for Kirtland's warblers in the annual population census. Furthermore, the current monitoring approach cannot determine their species detection probability or individual detection probability, which is essential to evaluate both red pine use and the accuracy of the census. From 2016–2018 we estimated density and detection probabilities in jack pine and red pine stands through repeated visits to a limited number of stands rather than single visits to many stands. Estimates of species detection probability indicated that ≥1 male Kirtland's warbler would be detected on most sites when any were present, but individual detection probabilities were less and varied by stand type, indicating that single visits to sites would underestimate numbers and that accurate estimation of detection probability was important for estimation of density in different stand types. We offer quantitative estimates of detection probabilities for determination of Kirtland's warbler population size in jack pine versus red pine stands in the same areas and breeding seasons. Managers of Kirtland's warblers should incorporate detection probabilities into population surveys to achieve more accurate estimates of population size.

Fungal Diversity in Multiple Post-harvest Aged Red Pine Stumps and Their Potential Influence on Heterobasidion Root Rot in Managed Stands Across Minnesota.

Thinning operations that occur in managed red pine (Pinus resinosa) stands, create tree stumps that can serve as a habitat for fungi, especially Heterobasidion irregulare, the cause of a serious root disease. Different fungi can colonize stumps early and the community of fungi can change over time as initial fungal species become replaced. Samples were collected from both the native and non-native range of red pine from stumps that were cut at different time periods. Stumps that were harvested at 0-1, 2-3, 5-6, and 10-12 years before sampling were used to provide data on the diversity of fungi that colonize tree stumps and how these communities can change over time as well as how they influence colonization of H. irregulare. Traditional culturing methods and Illumina MiSeq sequencing were used to identify the fungi in the samples. Of particular interest was Phlebiopsis gigantea, which can colonize cut stumps and prevent H. irregulare from becoming established. Overall, P. gigantea was the most abundant fungus isolated and sequenced via Illumina MiSeq. Results show that Phlebiopsis gigantea was isolated from 90% of all stumps sampled for sites harvested within 3 years of sampling in the native range of red pine compared to 33% in the non-native range. For Illumina MiSeq, 5,940 total amplicon sequence variants (ASVs) were detected. P. gigantea represented 14% of the total reads and composed 19% of the reads in the native range and 8% in non-native range of red pine. Furthermore, P. gigantea represented 38% of the reads for stumps that were harvested within 3 years of sampling in the native range of red pine compared to 14% in the non-native range. These results help demonstrate that a higher amount of P. gigantea is present in the native range of red pine and could be acting as a native biological control agent. Additional fungi, including Resinicium bicolor, Hypochnicium cremicolor, Leptographium spp., and others identified at different cutting times are also discussed. Finally, different diversity indices revealed similar, but slightly higher diversity for southern sites via Shannon and Simpson Diversity indices. Beta diversity demonstrated a similar species composition in stumps harvested at different times with these stumps being grouped together based on harvesting years.

Climate, site conditions, and stand characteristics influence maximum size-density relationships in Korean red pine (Pinus densiflora) and Mongolian oak (Quercus mongolica) stands, South Korea

This study examines the effects of climate, site index and structural diversity on maximum size-density relationships (MSDRs) for Korean red pine (Pinus densiflora Siebold & Zucc.) and Mongolian oak (Quercus mongolica Fisch. ex Ledeb.) which are widely distributed and abundant across South Korea. We used data collected between 2006 and 2015 from the Korean National Forest Inventory and stochastic frontier function regression to develop static self-thinning lines (STLs) for pure pine, pure oak, and pine-oak mixed-species stands. Climate variables, site condition (e.g., site index), and stand characteristics (e.g., structural diversity and pine proportion) were applied to the STLs to examine the factors affecting MSDRs and the effects of climate on MSDRs. Our results indicate that the slope and intercept values differed significantly between the three stand types, with the pine STL being steeper than other STLs. Degree days above 18 °C in spring (DD18_sp), degree days above 5 °C in spring (DD5_sp), and annual heat moisture index (AHM) mainly influenced the position of STLs. Increases in these climate variables (e.g., warmer and drier conditions) reduce maximum densities owing to increased evapotranspiration and water stress in stands. Increasing site index (SI) was associated with an upward shift in the position of the STL for pine, and the result shows that better site quality can improve carrying capacity and increase stand stocking. However, high stand stocking can encourage tree competition with increasing dryness and reduce maximum stocking. Higher stand structural diversity caused an upward shift in all STLs, and the effect of climate on the STLs of different structural diversities varied with stand type. Structurally diverse stands can stock more trees in their stands owing to efficient space use, especially with respect to shade tolerant species. Nonetheless, under drier conditions, trees in dense stands experience severe competition, and their carrying capacity decreases. Our results suggest that it is important to include stand density control in forest management plans to prepare for global warming in South Korea.

Predicting Post-Fire Tree Mortality in a Temperate Pine Forest, Korea

Warmer and drier conditions in temperate regions are increasing the length of the wildfire season. Given the greater fire frequency and extent of burned areas under climate warming, greater focus has been placed on predicting post-fire tree mortality as a crucial component of sustainable forest management. This study evaluates the potential of logistic regression models to predict post-fire tree mortality in Korean red pine (Pinus densiflora) stands, and we propose novel means of evaluating bark injury. In the Samcheok region of Korea, we measured topography (elevation, slope, and aspect), tree characteristics (tree/crown height and diameter at breast height (DBH)), and bark injuries (bark scorch height/proportion/index) at three sites subjected to a surface fire. We determined tree status (dead or live) over three years after the initial fire. The bark scorch index (BSI) produced the best univariate model, and by combining this index with the DBH produced the highest predictive capacity in multiple logistic regression models. A three-variable model (BSI, DBH, and slope) enhanced this predictive capacity to 87%. Our logistic regression analysis accurately predicted tree mortality three years post fire. Our three-variable model provides a useful and convenient decision-making tool for land managers to optimize salvage harvesting of post-fire stands.

Translocation of Carbon from Surface Organic Horizons to the Subsoil in Coarse‐Textured Spodosols: Implications for Deep Soil C Dynamics

Core Ideas O horizons account for the majority of DOM entering B horizons in these sandy soils. There was less exchange with SOM in sugar maple stands compared to red pine stands. Microbial processing of DOM inputs appears to be important in the formation of SOM. Dissolved organic matter (DOM) translocated from O horizons has been viewed as the main source of subsoil carbon (C) in Spodosols. However, recent studies in other soil types have concluded that little O horizon DOM reaches the subsoil directly. We investigated whether C derived from O horizons contributes to deep‐soil C stores in six Spodosol profiles under coniferous (red pine) or deciduous (sugar maple) forests. We used spectroscopic, stable‐isotope and pyrolysis‐gas chromatography/mass spectroscopy analysis of DOM and solid phase soil samples to assess whether O horizon C was transported directly to deep soil horizons or had been exchanged with mineral soil organic matter (SOM) pools. All three approaches indicated that O horizons are the source of the majority of DOM entering B horizons, with little contribution from desorbed SOM. Despite a greater stock of O horizon C in red pine stands, there was no difference between forest types in the quantity of C delivered to B horizons (18 g C m–2 y–1). However, C derived from O horizons accounted for ∼95% of the C entering B horizons in sugar maple stands, but only ∼80% in red pine stands. Molecular analysis of DOM and SOM also showed a greater resemblance of B horizon SOM to DOM in sugar maple stands; however, it also clearly indicated the importance of microbial processing of input C in the formation of B horizon SOM. Our results demonstrate the strong connection between O horizons and deep soil C stocks in these sandy Spodosols and indicate that future changes in the quantity or quality of DOM entering the mineral soil have the potential to alter the delivery of surface C to depth.

Size-growth relationship, tree spatial patterns, and tree-tree competition influence tree growth and stand complexity in a 160-year red pine chronosequence

Extended rotations have been suggested as a strategy for balancing timber production and ecological objectives. By lengthening the period of stand development, extended rotations may increase tree size inequality and other elements of structural complexity, thus reducing the disparity between managed and old-growth stands. A potential limitation of extended rotations is the tradeoff between reduced stand-level productivity and greater large-tree growth that typically occurs with stand age. The mechanisms driving this tradeoff have not been fully explored. To fill this knowledge gap, we investigated the size-growth relationship (SGR), tree spatial patterns, and tree-tree competition along an established 160-yr chronosequence of 19 single-cohort, unthinned red pine (Pinus resinosa) stands in northern Minnesota, USA. We analyzed SGR, a stand-level metric used to estimate the relative efficiency with which different sized trees utilize available resources, to assess how the relationship between tree size and growth changed over an extended period of stand development. We performed spatial analysis to examine whether tree spatial clustering, a criterion of structural complexity, increased with stand age. We modeled individual-tree biomass increment to test whether competition along the chronosequence was size-symmetric (access of individual trees to resources is directly proportional to size) or size-asymmetric (larger trees suppress the growth of smaller individuals by preempting resources), and how SGR, tree spatial patterns, and competition together influenced individual-tree growth. We found low SGR (i.e., disproportionately slow growth of larger trees compared to smaller trees) across the chronosequence, a finding that contrasts with hypothesized models of SGR during stand development but is consistent with previous research on pine-dominated systems. Tree spatial patterns trended towards clustering with stand age, indicating higher structural complexity over time. In agreement with our SGR findings, competition across the chronosequence was size-symmetric, suggesting that competition reduced individual-tree growth while maintaining relative size equality. Individual-tree biomass increment was strongly dependent on tree size, with the growth of small trees appearing relatively less affected by competition. Differences in SGR did not translate into individual-tree growth, and tree spatial clustering was associated with reduced growth, especially in larger trees. Our results indicate that disproportionately slow large-tree growth and size-symmetric competition throughout stand development may delay the emergence of stand structural complexity in extended rotation red pine stands. Silvicultural treatments may be required to promote stand structural complexity and increase large crop-tree growth.

Determining the quantity and quality of biomass obtained from the thinning of Turkish red pine stands

AbstractRed pine (Pinus brutia Ten.) is the most common tree species in Turkey, where it covers almost 6 million hectares. The first thinning of red pine stands is a fundamental tending measure that may yield between 4 and 12 dry tons of biomass per hectare. While this is not a very large amount per se, it is larger than obtained from the recovery of logging residues from final felling operations, which have represented the main subject of previous studies. What is more, valorization of the non‐commercial biomass component can boost work productivity and increase owner revenues, with strong benefits on the financial sustainability of an operation that normally incurs substantial cost and tends to be neglected. Therefore, increased use of biomass can support proper tending of young stands and a general improvement of their quality and future value. The study also indicates that small‐tree size favors whole‐tree harvesting, even when performed with animal or manual power, as customary in Turkey and in most developing economies. Whole‐tree chipping is probably the best option in stands growing on poor yield sites, whereas multi‐product harvesting is advisable on good yield sites. This study addresses specifically Turkish red pine, but it frames a general paradigm that applies to most forest stands and countries, and as such it can be generalized to a great extent. © 2017 Society of Chemical Industry and John Wiley & Sons, Ltd

Deposition pattern and throughfall fluxes in secondary cool temperate forest, South Korea

Chemistry and deposition fluxes in the rainfall and throughfall of red pine (Pinus densiflora), black locust (Robinia pseudoacacia), and chestnut (Castanea crenata) monocultures, and mixed red pine–black locust–chestnut stands were examined in a nutrient-limited cool temperate forest of central South Korea. Throughfall was enriched in both basic and acidic constituents relative to rainfall, suggesting that both dry deposition and canopy leaching are important sources of throughfall constituents. Net throughfall fluxes (NTFs) of cations and anions significantly differed among four different stands as well as seasonally. Red pine exhibited highest fluxes (TF and NTF) for Ca2+, black locust for K+, mixed stands for Mg2+, and chestnut for Na+. In contrast, NTF of SO42-, NO3−, and NH4+was highest in the red pine, intermediate in the chestnut and mixed stands, and lowest in the black locust. In general, canopy uptake of H+ and NH4+ for all stands was higher in summer than in winter. Dry deposition appears to play a major role in atmospheric deposition to this cool temperate forest, especially in summer. Dry deposition for both cations and anions displayed high spatial variability, even though stands were adjacent to one another and experienced identical atmospheric deposition loads. Canopy leaching of K+ (95–78% of NTF), Mg2+ (92–23% of NTF), and Ca2+ (91–12% of NTF) was highest for the black locust, lowest for chestnut, and intermediate for the red pine and mixed stands. The present study documented significant changes in throughfall chemistry and NTF among different forest stands, which presumably be related with the differences in the canopy characteristics and differences in their scavenging capacity for dry deposition and canopy exchange. Difference in the canopy retention of H+ and base cation leaching suggests that canopy exchange was mainly driven by weak acid excretion and lesser by H+ exchange reaction. Our results indicate that despite a high base cation deposition, a combination of higher input of acidifying constituents, low soil pH, and total acidic deposition approaching South Korean critical loads make regional forest vulnerable to acidification.

Heterotrophic Soil Respiration Affected by Compound Fertilizer Types in Red Pine (Pinus densiflora S. et Z.) Stands of Korea

This study was conducted to evaluate the effects of fertilizer application on heterotrophic soil respiration (Rh) in soil respiration (Rs) components in red pine stands. Two types of fertilizer (N3P4K1 = 113:150:37 kg·ha−1·year−1; P4K1 = 150:37 kg·ha−1·year−1) were applied manually on the forest floor for two years. Rs and Rh rates were monitored from April 2011 to March 2013. Mean Rs and Rh rates were not significantly affected by fertilizer applications. However, Rh in the second year following fertilizer application fell to 27% for N3P4K1 and 17% in P4K1 treatments, while there was an increase of 5% in the control treatments compared with the first fertilization year. The exponential relationships between Rs or Rh rates and the corresponding soil temperature were significant (Rh: R2 = 0.86–0.90; p < 0.05; Rs: R2 = 0.86–0.91; p < 0.05) in the fertilizer and control treatments. Q10 values (Rs increase per 10 °C increase in temperature) in Rs rates were lowest for the N3P4K1 treatment (3.47), followed by 3.62 for the P4K1 treatment and 3.60 in the control treatments, while Rh rates were similar among the treatments (3.59–3.64). The results demonstrate the importance of separating Rh rates from Rs rates following a compound fertilizer application.

Understory species and functional diversity in a chronosequence of jack pine and red pine stands in the south-central boreal forest

Dominant tree species and anthropogenic disturbances influence understory taxonomic diversity (TD) and species traits (functional diversity, FD) in managed forests. We compared understory TD and FD in managed jack pine (Pinus banksiana Lamb.) stands and red pine (Pinus resinosa Ait.) plantations. Understory herbs, grasses, shrubs, and nonvascular species were assessed in 1 m2 quadrats on two perpendicular line transects. Data were analyzed using generalised least squares regression, and multivariate fourth corner and RLQ analyses. Although there were few differences in understory species communities, red pine plantations appeared to impose weak environmental filters on TD in ways that were absent from the jack pine stands. Taxonomic diversity declined with age in red pine but not in jack pine, and may have been affected by the accumulation of litter cover in red pine stands. Although vegetation cover was lower in red pine than in jack pine, species richness on a percent cover basis was greater, and saturated at high cover levels in jack pine. Functional richness and evenness were unaffected by overstory species, but high litter cover favoured higher values of functional divergence. These results imply that there was a high level of functional redundancy among species for the suite of traits that we analyzed.

Basal area effects on a short-term nutrient status of litter fall and needle litter decomposition in a Pinus densiflora stand

Abstract This study was conducted to examine litter fall, litter decomposition, and a short-term nutrient (C, N, P, K, Ca, and Mg) status for one year at various levels of basal area (21.4, 27.0, 30.8, 37.0, 42.1, and 46.7 m 2 ha -1 ) in approximately 40-year-old red pine ( Pinus densiflora S. et Z.) stands in the Hwangmaesan mountain forest in Korea. Monthly fluxes of litter fall components such as needles, broad leaves, branches, bark and total litter fall followed a similar pattern at various levels of basal area. Mean annual needle, bark and total litter fall fluxes were positively correlated with increased basal area ( p <0.05), but the woody litter such as branches and cones was not correlated with basal area. Carbon and K concentra-tions of needle litter were negatively correlated with increased basal area, while nutrient (C, N, P, K, Ca, and Mg) fluxes were positively correlated with the basal area treatments. Remaining mass, N and P concentration and remaining N and P stocks in decomposing needle litter were not affected by the basal area. However, the concentration and stocks remain -ing of K, Ca, and Mg from decomposing litter were positively correlated with increased basal area during the initial three months of decomposition. The results indicate that basal area has an impact on nutrient cycles through change in litter fall and litter decomposition processes; thus, the dynamics of nutrient cycles based on a stand scale could differ consider -ably with different levels of basal area in red pine stands.

Dendroclimatic analysis of red pine affected by Diplodia shoot blight in different latitudinal regions in Michigan

Drought and intraspecific competition in red pine (Pinus resinosa Ait.) stands in Michigan have been implicated as predisposing factors for increased shoot blight risk caused by Diplodia pinea Desm. The overall objective of this study is to examine the interactive effects of drought, other climatic factors, and biotic factors (intraspecific competition) on productivity and growth of red pine forests affected by Diplodia shoot blight. This study incorporates a dendroclimatic approach that allows the retrospective examination of past annual diameter growth in relation to historical climate and the assessment of the potential impacts of future climate change. A total of 20 red pine stands were sampled in two latitudinal regions (the Upper Peninsula (UP) and the Lower Peninsula (LP) regions) of Michigan across two levels of initial stand density (low vs. high) and two levels of forest health condition (healthy vs. D. pinea affected). The full dendroclimatic relationships revealed in this study indicated that other climatic factors, in addition to summer drought stress, impacted red pine radial growth. Overall, red pine radial growth was generally more affected by precipitation and moisture index than solely by temperature variables. The radial growth response to climate depended on latitudinal region: summer moisture stress was more influential in the LP; cold spring and early summer temperatures negatively impacted growth more in the UP; and the degree of winter harshness was more of a factor in the UP. Crown damage caused by winter damage may have predisposed red pine stands to D. pinea affection by providing an easier entry point for fungal infection. Negative relations with precipitation in D. pinea affected stands may be due to increased dispersal of spores in D. pinea affected stands with significant rain and any increased storm and wind activity. Projections of radial growth under future scenarios of climate change indicate that climate warming has the potential to increase growth mainly in red pine stands in the UP region where growth has historically been limited by cool temperatures early in the growing season. Under the moisture index model, growth of red pine under the drier (A2) climate change scenario, only the D. pinea impacted high-density stands in the LP region are projected to show a significant decrease in growth by the middle (2041–2070) and final (2071–2100) projection periods. Model-based projections of forest growth in Michigan generally do not account for forest health issues such as invasive pathogens. The current study therefore provides a new understanding of the role of forest pathogens under future climate change.

Habitat Associations of the Eastern Hognose Snake at the Northern Edge of Its Geographic Distribution: Should a Remnant Population Guide Restoration?

Heterodon platirhinos (Eastern Hognose Snake [EHS]) is a species of conservation concern in the northeastern United States. As an initial step toward potential restoration, we examined habitat associations of a peripheral population of EHS in New Hampshire. At the landscape scale, transmitter-equipped snakes were found most often in developed lands, followed by, in order of frequency, mixed forest, Pinus strobus/P. resinosa (Eastern White/ Red Pine) stands, and 7 other cover types. Within individual home ranges, snakes selected Tsuga canadensis (Eastern Hemlock) stands most often, followed by, in order of frequency, White/Red Pine stands, mixed forest, Fagus grandifolia/Quercus spp. (American Beech/ oak) stands, and 6 other cover types. Compared to random locations, microhabitat features at snake activity sites included higher ground-surface temperatures, closer proximity to wetlands, less canopy closure, and more abundant shrubs, ground debris, and rock cover. When combined with a previous study conducted in the same area, we found that cover-type associations (mesic forest) of this population differed from known affinities (open, xeric habitats) of EHS throughout much of its geographic distribution. Home ranges were also larger than those reported in most studies. We suspect our population persists because it occurs in a large parcel of land with limited human alteration and use. Habitat there is suitable but likely is not optimal. Such limitations should be considered when selecting sites to establish new populations of EHS in northern regions.

Kızılçam ve Karaçam Meşcerelerinde Yaprak Alanı İndeksi (YAİ) ile Bazı Meşcere Özellikleri Arasındaki İlişkiler

Leaf are index (LAI) which is commonly used for analyzing of canopy cover and a direct measurement of active leaf area is closely related to forest and site productivity. Various methods have been developed for the estimation of LAI. Recent years, hemispherical photograph that is one of the methods of LAI estimation has been used frequently. This study investigates the relationships between LAI and stand age, mean diameter, density, top height, green tree height, basal area and litter in Turkish red pine and black pine stands in Bozdag region, Denizli. The measurements were carried out in 39 systematic sampling plots 24 of which in Turkish red pine and 15 in black pine stands. LAI values which calculated via the hemispherical photographs ranged between 0.77 and 2.56 m2 m-2and between 0.78 and 4.66 m2 m-2 in Turkish red pine and black pine stands respectively. Regression analysis results revealed there are positive correlations between LAI value and stand age, mean diameter, top height, green tree height, basal area and litter in Turkish red pine whereas LAI value in black pine stand has negative correlation with stand age and mean diameter. Based on our results, changes of stand type are nearly effect on LAI and the correlations between LAI and some stand properties vary according to the species

Carbon storage and stand conversion in a pine-dominated boreal forest landscape

Although climate change is expected to have wide-ranging effects on the distribution and character of forest biomes, major changes to forest cover are enacted as part of normal forest management. In this paper, I compared ecosystem carbon storage in a chronosequence of forest stands dominated by two common pine species – jack pine (Pinus banksiana Lamb.) and red pine (Pinus resinosa Ait.) growing on homogeneous beach ridge sands in Sandilands Provincial Forest (SPF), Manitoba. In SPF, there has been a history of converting stands formerly dominated by jack pine to regularly spaced red pine plantations. Ecosystem carbon (C) storage was dominated by soil and live tree ecosystem components. However, while there were no interspecific differences in soil storage, the red pine stored a larger proportion of ecosystem C in live trees than jack pine, a difference that appeared to grow greater with age. Differences in C storage appeared to be driven by divergent patterns of longevity and vulnerability to senescence and disturbance (e.g. windthrow) in jack pine and red pine. These differences in life history traits also appeared to be responsible for contrasting accumulation patterns of woody debris and litter with stand age. Consistently higher canopy cover in red pine stands may also have been responsible for age-related reductions in C storage in the herbs and short shrubs (those <1.5m tall) in red pine. These results indicate that changing the character of forest cover, even when closely related species are substituted for each other, can produce large differences in overall C storage, as well as in the distribution of C among ecosystem compartments.

Clearcut with seed trees in red pine forests associated with increased occupancy by Eastern Whip-poor-wills

Forest management is often used to increase and maintain early-successional forest habitat for breeding birds by emulating natural disturbance with harvesting. However, quantified habitat-use relationships are often lacking, which makes forest management planning challenging for some species. One such species is the Eastern Whip-poor-will (Antrostomus vociferus), a crepuscular, insectivorous, neotropical, migrant bird, designated as a species at risk throughout most of its breeding range. Thus, we determined occupancy of Eastern Whip-poor-wills at 37 sampling points in red pine (Pinus resinosa)-dominated stands harvested using clearcut with seed trees and in white pine (P. strobus)-dominated stands harvested using uniform shelterwood in June 2013 in eastern Algonquin Provincial Park, Ontario. In red pine stands, we found that model-predicted site occupancy increased by 3.3 times from 0.23 where young (<16years since harvest) clearcuts were absent to 0.76 where young clearcuts were present. Shelterwood harvesting in white pine stands, by contrast, was unassociated with occupancy. Our data suggest that an aggregated mean total of 12ha of clearcuts per 100ha (interquartile range: 1.5–18ha) of mature pine-dominated forest is associated with significantly higher occupancy by breeding Eastern Whip-poor-wills, and that the clearcuts can be composed of various sizes (interquartile range: 3–42ha) and ages (interquartile range: 5–24years since harvest). Given that similar relationships have been found by others elsewhere, clearcuts may increase the occupancy and abundance of breeding Eastern Whip-poor-wills in other regions and forest types throughout northeastern North America.

Woody debris volumes and carbon accumulation differ across a chronosequence of boreal red pine and jack pine stands

Boreal forests are thought to store more than 30% of the world’s terrestrial carbon (C), much of it in the form of dead wood. Harvesting, stand transformation, and climate change the storage capacity of this carbon pool and improved quantification of C storage is needed to improve the accuracy and coverage of C accounting in Canadian forests. In this study, we compared wood volumes and C storage in coarse woody debris (CWD), fine woody debris (FWD), and standing dead wood (snags) in a 94-year chronosequence of jack pine (Pinus banksiana Lamb.) and red pine (Pinus resinosa Ait.) stands in the Sandilands Provincial Forest, southeastern Manitoba. In our data set of 20 jack pine and 17 red pine stands, jack pine stands supported higher volumes of CWD, snags, and sparsely distributed FWD than red pine stands. Mean CWD volume and C mass were, respectively, 18.6 m3·ha−1 and 2.6 tonnes (t)·ha−1 for jack pine and 11.3 m3·ha−1 and 1.1 t·ha−1 for red pine. Snag volumes and C mass were, respectively, 1.8 m3·ha−1 and 0.25 t·ha−1 for jack pine and 0.26 m3·ha−1 and 0.04 t·ha−1 for red pine. CWD loads in jack pine stands followed a U-shaped distribution with stand age, and snag loads in jack pine increased linearly with time. No such significant trends for CWD or snags were observed in red pine. Our results confirm that stand conversion from fire-origin jack pine to red pine plantations has the potential to significantly reduce and alter temporal patterns of dead wood accumulation across the landscape.

The effect of nitrogen addition on soil organic matter dynamics: a model analysis of the Harvard Forest Chronic Nitrogen Amendment Study and soil carbon response to anthropogenic N deposition

Recent observations indicate that long-term N additions can slow decomposition, leading to C accumulation in soils, but this process has received limited consideration by models. To address this, we developed a model of soil organic matter (SOM) dynamics to be used with the PnET model and applied it to simulate N addition effects on soil organic carbon (SOC) stocks. We developed the model's SOC turnover times and responses to experimental N additions using measurements from the Harvard Forest, Massachusetts. We compared model outcomes to SOC stocks measured during the 20th year of the Harvard Forest Chronic Nitrogen Amendment Study, which includes control, low (5 g N m -2 yr -1 ) and high (15 g N m -2 yr -1 )Na ddi- tion to hardwood and red pine stands. For unfertilized stands, simulated SOC stocks were within 10 % of measurements. Simulations that used measured changes in decomposition rates in response to N accurately captured SOC stocks in the hardwood low N and pine high N treatment, but greatly underestimated SOC stocks in the hardwood high N and the pine low N treatments. Simulated total SOC response to experimental N addition resulted in accumulation of 5.3-7.9 kg C per kg N following N addition at 5 g N m -2 yr -1 and 4.1-5.3 kg C per kg N following N addition at 15 g N m -2 yr -1 . Model simulations suggested that ambient atmospheric N deposition at the Harvard Forest (currently 0.8 g N m -2 yr -1 )h as led to an increase in cumulative O, A, and B horizons C stocks of 211 g C m -2 (3.9 kg C per kg N) and 114 g C m -2 (2.1 kg C per kg N) for hardwood and pine stands, respectively. Simulated SOC accumulation is primarily driven by the modeled decrease in SOM decomposition in the Oa horizon.