Intensive Forest Management Practices Research Articles

Experimental evaluation of herbicide use on biodiversity, ecosystem services and timber production trade‐offs in forest plantations

Abstract The value of non‐commodity ecosystem services provided by forests is widely recognized, but intensive forest management practices are increasing, with uncertain consequences for a multitude of these services. Quantitative relationships among biodiversity conservation, timber production and other ecosystem services remain poorly understood, especially during the early‐successional period of intensively managed forestlands. We manipulated management intensity in regenerating forest plantations to test the prediction that treatments aimed at maximizing timber production decrease biodiversity conservation and non‐timber services. We measured species richness of 3 taxonomic groups and 13 proxies for provisioning, cultural and regulating services within stands randomly assigned to one of the three herbicide application intensities or an untreated control. Herbicides increased allocation of net primary production to crop trees, increasing projected timber volume and revenues at 40‐ and 60‐year harvest ages. Commonly used herbicide prescriptions reduced culturally valued plants by 71%, wild‐ungulate forage by 41%, avian richness by 20% and pollinator floral resources by 42%, the latter being associated with 38% fewer pollinator species. However, agriculturally valued bumblebees, pollination of blueberries, avian‐mediated arthropod control, wild ungulate observations and regulation services tied to forest productivity appeared unaffected by increasing management intensity and timber production. Species richness and flora‐provided services in young forest plantations exhibited strong trade‐offs with projected timber production, whereas post‐treatment vegetation regeneration and site‐level variation likely maintained a range of other services. Although vegetation recovery is important for supporting wildlife and some ecosystem services on industrial forestlands, it is unlikely that any single prescription can optimize both timber and non‐timber benefits to society across managed forest landscapes. Instead, producing different services in discrete portions of the landscape may be necessary. Synthesis and applications. We tested the effects of intensive forest management via herbicides on ecosystem services and found that biodiversity responses and services from early‐successional vegetation trade‐off against timber production. A number of services appeared to be compatible with timber production, although no single prescription optimized the full range of services. Stand‐level biodiversity conservation and a variety of services could potentially be provided by treatment skips and less‐intensive management on productive sites, although it is unlikely that all services can be optimized without landscape‐level planning.

Wild ungulates compound herbicide-mediated simplification of early successional plant communities in forest plantations

Understanding the degree to which management interacts with ecological processes to drive the structuring of biodiversity remains a central challenge in ecology. For instance, the effects of herbivores on post-disturbance vegetation development may depend on the degree to which anthropogenic interventions have altered plant communities.We hypothesized that by simplifying plant species composition at local scales, intensive forest management practices should amplify herbivore-mediated changes in early-successional vegetation development and diversity at multiple levels of biological observation (i.e., alpha, beta, and gamma diversity). To test this hypothesis, we implemented a six-year experiment that manipulated post-timber harvest vegetation establishment via a gradient in vegetation management intensity (i.e., herbicides), and quantified compositional changes with and without wild-ungulate herbivores.Increasingly intensive herbicide treatments suppressed broadleaf vegetation and reduced plant diversity at alpha and gamma levels, while the effects of wild-ungulates were most evident in measures of community change and beta diversity for a commonly applied treatment type. Following the broad-spectrum and follow-up herbaceous treatment combination, herbivory contributed to the suppression of vegetation cover, slowing plant community development by 21%, and resulting in 27% less among-plot heterogeneity (i.e., lower beta diversity). We found no effects of herbivory alpha diversity, but the divergence in communities subjected to herbivory resulted in disparate community composition and lower gamma diversity.Herbicide and herbivore-mediated alterations in community composition was due the suppression of broadleaf species and subsequent release of common herbivory-tolerant herbaceous species. Although herbivory also slowed vegetation development without herbicides, the high diversity and abundance of broadleaf forages likely buffered untreated sites from the herbivore-mediated alterations of plant composition at alpha, beta, and gamma levels.The variation in effects of herbicide and herbivory in this experiment highlight the importance of testing for interactions between natural and anthropogenic agents on vegetation development and quantifying diversity responses beyond local scales. These results also suggest that large herbivores may contribute to management-induced simplification of young forests, with potential implications for successional processes and regional biodiversity conservation.

有机肥和植被去除管理对人工林土壤节肢动物多样性的影响

施用有机肥和林下抚育（植被去除）是人工林重要的管理措施；土壤节肢动物物种丰富，是土壤生态系统的重要组成成分，对环境变化敏感，可以作为森林管理的指示生物。人工林植被去除和施肥管理影响土壤性质、资源输入量及微生物多样性，从而影响土壤节肢动物多样性，但是相关研究还十分缺乏。以沿海地区杨树人工林为对象，研究了施用有机肥和林下植被去除对土壤节肢动物的数量和多样性的影响。结果表明，有机肥和植被去除管理对不同土壤层土壤节肢动物的数量和多样性指标影响不一致。有机肥增加0-10 cm深度土壤节肢动物总数量、蜱螨目数量，降低土壤节肢动物群落物种丰富度、均匀度和Shannon多样性指数；植被去除减少0-10 cm深度土壤节肢动物总数量和弹尾目数量，降低均匀度指数。两种处理对10-20 cm深度土壤节肢动物群落的数量和各多样性指标影响不显著。总体来说（0-20 cm），有机肥处理土壤节肢动物的数量显著增加，优势类群前气门亚目（Prostigmata）的数量增长为对照的4倍，但是土壤节肢动物群落的均匀度和Shannon多样性指数显著降低，这可能是土壤节肢动物优势类群前气门亚目密度急剧增加，而物种丰富度没有变化所导致；此外，施用有机肥增加了土壤有机质、总氮、有效磷的含量，降低土壤pH值，并且与前气门亚目密度显著相关。林下植被去除没有影响0-20 cm深度土壤节肢动物的数量和各多样性指标。;Plantations provide important wood resources and also play an important role in mitigating climate change. Establishing poplar plantations is a common practice for improving the quality of reclaimed coastal saline soils in Eastern China. Organic fertilizer application and understory plant removal are two common management practices to promote plantation growth. Soil arthropod is a critical component in the ecosystem processes of organic matter decomposition and nutrient cycling. The abundance and diversity of arthropods can reflect changes in soil quality and ecosystem functionality. Studies have demonstrated that the abundance and diversity of soil arthropods might be impacted by changes in the quality and quantity of forest understory plant materials, as well as soil chemical and physical properties. However, the extent to which intensive forest management practices to alter soil arthropod communities remains elusive. In this study, we examined the effects of applying organic fertilizers (OF) and removing understory plants (UP), on the abundance and diversity (i.e. richness, evenness, and Shannon's index) of soil arthropods of poplar plantations in a reclaimed coastal area of northern Jiangsu Province, China. We found that Acari and Collembola were the two of the most abundant soil arthropod groups. The OF application significantly increased the total abundance of soil arthropod and the abundance of Acari, significantly decreased diversity index while UP removal decreased the total abundance of soil arthropod, the abundance of Collembola, evenness in 0-10 cm soil. Both of the two practices had no impact on the total abundance and diversity index at 10-20 cm soil. As a whole 0-20 cm depth of the soil, the application of the OF significantly increased the total abundance of soil arthropods, while it decreased the evenness and Shannon's index. The abundance of Prostigmata mites increased almost four folds with the application of the OF treatment in contrast to the control. The increased abundance of dominant groups led to the decrease in the arthropod evenness and Shannon's index based on the Order level. In addition, it was also presumably a consequence of reduced soil pH and improved soil properties (e.g., OM, TN, AP) with the application of the OF in this reclaimed coastal saline soil. The removal of understory plants did not significantly influence the abundance, richness, evenness and Shannon's index of soil arthropods in 0-20 cm depth of soil. Our results suggested that the organic fertilizers application is a preferable management practice to understory plant removal in order to elevate the abundance of soil arthropods while promoting poplar plantation productivity.

Can’t see the Woodlark for the trees? Commercial forests as a habitat for a bird of conservation concern

This study investigated the extent to which intensive forest management practices influence a widespread bird of conservation concern, the Woodlark Lullula arborea. We compared trends of the studied population in Notec Forest, Poland during 2010–2014 against country-wide monitoring data, and populations of the forest interior versus forest edge dominated landscapes (forest-agricultural area mosaic). We also studied the influences of forest management practice (clearing size, stand structure, forestry activities on restock sites, harvesting in the neighboring habitat, and retaining tree aggregates) on the population of this species. Changes in woodlark numbers, habitat availability, and quality differences among studied sites and years were assessed using ANOVA. The influence of habitat characteristics on woodlark occupancy and abundances were tested by Generalized Estimation Equations, while the magnitude of influences in the study years was compared by Random Forest algorithm (as were population trends). Over the four study years, 419 woodlark pairs occupied 336 patches, with a maximum of 127 pairs. The number of woodlark pairs fell by 40% on the studied areas over the period, in line with declines across Poland as a whole. In our study system, population trends did not differ between forest and forest- agro mosaic landscapes. Size, age and number of available habitats did not differ either temporally or spatially during the study. Retention of unfelled trees in clearfell areas and forest works in the nearby sites, however, showed slight differences among the sampling polygons. Larger habitat patch size and restock areas under five years favored woodlarks. Less important but still significant positive influences were a higher proportion of retained trees and elongated shape of the habitat patches. Forestry activities on the neighbor stands were correlated with increased woodlark abundances, which is an unexpected result. Moreover, forestry provides suitable habitats for woodlarks in a dynamically changing arrangement. The magnitude of the studied factors’ influences on woodlarks showed a very high difference between study years, with the highest values in the years where woodlarks are the most numerous. In conclusion, we found no evidence that contemporary forestry adversely affects Woodlark habitat occupancy. Our study suggests that while managing land for one ecosystem service (timber), an apparent dis-benefit (loss of recreational attractiveness) might benefit some semi-open habitat species.

Effects of environmental factors and forest management on landscape-scale forest storm damage in Turkey

Windstorms have recently caused noteworthy destruction across the Northern forests of Turkey. The intensive forest management practices applied for more than 60+ years may unknowingly have resulted in wind-sensitive forests in the region. After a storm, the forest service salvages the losses, but no further precaution is taken against future storms. To our knowledge, there has not been any research looking into the cumulative effects of environmental factors on storm damage in Turkish forests. Maxent, which is an ecological niche model, might help decision-makers in developing forest management strategies against storms given its ease of use, known successful performance, and flexible variable evaluation approach. This study revealed that management preferences were mainly responsible for forest storm damage in Kastamonu Province, Turkey. Excessive wind cause serious damages to individual trees and forest stands. When unintentionally coupled with the forest management preferences, catastrophic levels of damage might be unavoidable. The main objective was to assess the environmental factors contributing to the impact of a strong windstorm that occurred between March 14 and 15, 2013 and resulted in 1.5-million m3 timber losses in the Kastamonu Regional Directorate of Forestry. Maximum entropy modeling (Maxent) and geographic information systems (GIS) were used to evaluate the factors contributing to the forest damage. Stand type, diameter class, and elevation were the most important variables affecting the level of wind damage. The pure and mixed coniferous stands were the hardest hit when compared with the deciduous stands. The damage increased as the density of forest roads grew. It was concluded that windstorms pose serious threats to Turkish forests. Storm damage risks must therefore be integrated into forest management. In order to better understand the environmental factors contributing to the destructive effects of windstorms in forests, it would be best to focus on the telltale signs pointing the wrong-doing in forest management preferences at larger environmental scale rather than looking for reasons behind the occurrences of scattered small-scale damage.

Habitat Selection by the European Nightjar Caprimulgus europaeus in North-Eastern Poland: Implications for Forest Management

Research Highlights: Intensive forest management practices generally have a negative effect on biodiversity. However, the creation of new, open habitats as a consequence of timber harvesting within large areas of woodland may be favorable to some bird species. Background and Objectives: Habitat selection of the European Nightjar Caprimulgus europaeus in a coniferous woodland area in northeastern Poland was studied in order to specify management recommendations. Materials and Methods: To define the influence of various environmental parameters on territory occupation, 11 micro- and 3 macrohabitat factors were analyzed. Results: Denser vegetation in the ground layer deterred birds from nesting in clearings with such characteristics. Moreover, Nightjars preferentially inhabited sites adjacent to young stands of trees. Birds preferred plots with a higher number of clearings in the neighborhood, as this enabled them to enlarge their foraging area. Other microhabitat factors (e.g., the type, age and area of clearings), as well as macroscale factors like distances to the forest edge, nearest roads and human settlements, were of no importance. Conclusions: Knowledge of the Nightjar preferences may be useful in working out a compromise between an appropriate level of clear-felling and conservation of other bird species requiring preservation of old tree stands.

Long term effects of management practice intensification on soil microbial community structure and co-occurrence network in a non-timber plantation

Intensive forest plantation management practices, such as use of inorganic chemical fertilizer and herbicides improve productivity, however, their environmental impacts on plantation soil microbial communities and its interaction pattern remain unclear. In this study, we investigated associations between management practice intensities (nutrient-herbicide, nutrient-mowing and manure-mowing), environmental factors including plant coverage, pH, exchangeable calcium (Ca2+), aluminium ion (Al3+), total organic carbon (TOC), C to N ratio (C/N) and soil moisture (SM), and microbial community structure in Chinese hickory (Carya cathayenses) plantations cultivated on two soil types (calcareous and yellow soils). Our results demonstrated that long-term management practices with different intensities significantly changed certain soil environmental factors, and revealed a significant impact on both α and β-diversity of soil bacterial and fungal communities. Specifically, significant higher values of plant coverage, pH, Ca2+, TOC, C/N and SM and lower value of Al3+ were observed under manure-mowing management. Calcareous soil showed significantly higher pH, Ca2+ and TN contents and lower AP values than yellow soil across all three operating intensities. The bacterial community structure was different between the calcareous and yellow soil, but there was no difference for the fungi. Edaphic properties such as pH, Ca2+, TOC and TN were shown to play crucial roles in microbial community structuring, while vegetation-associated factors (vegetation coverage and Al3+) were correlated with fungal community structure. The complexity of microbe co-occurrence network decreased as management practice intensified. The keystone taxa including Bradyrhizobium, Reyranella and Phaselicystis in bacterial network and Rhizophydium and Microascales in fungal network were only observed under manure-mowing, with ecological functions mainly involved in organic carbon degradation and nitrogen fixation. Our results provide insight into the interactions between management practice intensities and soil microbial community characteristics and have implications for the optimization of sustainable forestry management practices and maintenance of microbial diversity and network complexity in over-managed forest plantations.

Diversity and function of soil bacterial communities in response to long-term intensive management in a subtropical bamboo forest

Intensive forest management practices, such as fertilization, understory removal and deep tilling, play an important role in improving plant growth in forests through altering nutrient availability and soil structure. However, how such management affects soil microbial community diversity and functions related to nutrient cycling remains largely unknown. In this study, we investigated the responses of soil bacterial community composition and enzyme activities involved in C, N and P cycling to long-term intensive management, and identified the critical determinants that regulated them across a chronosequence of Moso bamboo forests (0, 10, 15, 20 and 25 years of intensive management) in subtropical China. Our results demonstrated that intensive management decreased soil pH and aggregation and increased mineral nutrient contents. Illumina MiSeq sequencing showed that significant (P < 0.05) shifts of the soil bacterial community composition occurred after 15 years of management. Diversity indices (phylogenetic diversity, OTU richness and Chao1) generally decreased after 15 years of management. Soil pH, NO3−-N, and available P and K contents were key factors shaping the bacterial community composition. Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) predicted lower functional diversity of soil bacterial microbiomes as related to the cycling of amino acids and carbohydrates after 15 and 20 years. The activities of β-glucosidase and phosphatase decreased markedly after 15 years of intensive management, but rebounded after 25 years. Structural equation modeling provided evidence that the response of soil enzyme activities to forest management was mediated by changes in bacterial composition and diversity. Our study suggests that intensive forest management decreases microbial diversity indices and changed community composition, which could have direct consequences for soil functioning.

Legacy effects of logging on boreal forest understorey vegetation communities in decadal time scales in northern Finland

We followed how forest thinning, repeated twice during a period of 93 years, altered understorey plant community composition, affected the succession of forest understorey vegetation and the accumulation of logs in the long-term. The study was carried out in northern Finland by resampling 20 permanent experimental plots, established after a wildfire in 1920. Understorey vegetation was inventoried in 1961, 1986 and 2013 with forest thinning treatments done in 1953 and 1987, using four and three different harvesting intensities, respectively. We found succession to override the effects of forest logging until the latest study period (2013). We observed negligible long-term effects of logging on understorey communities during the two mid-successional stages (1961, 1986), when the forest was 41 and 66 years old respectively. The impacts of logging on understorey vegetation were strongest in the latest successional stage (2013), the forest being at the age of 93 years. In the latest successional stage (2013) logged plots had less coarse woody debris than unlogged plots. Forest management thus influenced the key feature for forest biodiversity and potential habitats for endangered species. These findings are of major interest since the studies of long-term impacts of less intensive forest management practices are scarce. Our results suggest that in addition to possible immediate impacts, harvesting treatments have legacy effects (subtle or delayed inherited effects of forestry in the past) that influence the forest understorey vegetation community composition and the amount of coarse woody debris. This finding deserves special attention when planning of species conservation, multiple use of forests and sustainable forestry.

Herbicides Exert Weak and Variable Effects on Microclimate in Early-Seral Forests

Ecosystem modification driven by anthropogenic land-use and land-cover change is one of the leading drivers of global biodiversity declines. Simultaneously, ongoing climate change is modifying ecosystems and will have far-reaching impacts on the structure and function of ecological communities. Rising surface temperatures are predicted to have negative effects on plants and animals, but such predictions are typically broad and poorly matched to the spatial scale at which most organisms experience the environment. Microclimate thermal regimes are often moderated by land-cover, and intensive forest management practices have the potential to either ameliorate or exacerbate climate change effects on biota. In this study, we examined the degree to which air temperature varied across an experimental gradient of herbicide application intensity within early-seral forests in the Coast Range mountains of western Oregon. We evaluated stand-level air temperatures in regenerating stands subjected to light, moderate, and intensive herbicide treatments, as well as a no-spray control. We examined whether daily temperature measurements (minimum, mean, and maximum) and their associated coefficients of variation were influenced by herbicide treatments. We found that herbicide treatments had some influence on mean and maximum air temperatures, but not on minimum temperature or on measures of temperature variability. However, temperature effects were small (< 0.5 °C), the direction of these effects were inconsistent, and pairwise contrasts often failed to detect significant differences after accounting for multiple comparisons. Our results suggest that post-harvest vegetation management has limited impacts on fine-scale air temperatures and is unlikely to either amplify or buffer the projected effects of climate change within early-seral forests.

Assessment of sustainability of forest management practices on the operational level in northwestern Russia – a case study from the Republic of Karelia

ABSTRACTThe main aim of the article is to assess the consequences of newly proposed legislative initiative on introducing intensive forest management practices in Russia. Implementation of norms and its effect on sustainable forest management practices have been analysed in this study on one enterprise operating in the Republic of Karelia. This meant modelling of forest growth, clear cuts and regeneration within 100 km radius from the mill for two alternative management scenarios with fixed demand of wood based on current norms and decreasing harvesting age to half from the current. Wood demand of the enterprise, structure and accessibility of forest resources, i.e. forest road infrastructure were taken into account in the analysis. Both forest management scenarios decreased the total growing stock significantly, and therefore considered as non-sustainable practices. In addition, forest age structure was more uneven for both scenarios at the end of the simulation period. Comparison of two alternative management practices showed that the implementation of intensive forest management in Russia requires new norms that would be based on principles of sustainable forest management.

Linking soil fungal community structure and function to soil organic carbon chemical composition in intensively managed subtropical bamboo forests

Intensive forest management practices such as organic mulching and heavy fertilization can affect soil microbial composition and function, and soil organic carbon (SOC) forms. However, the linkage between soil microbial community composition and SOC forms is poorly understood in bamboo (Phyllostachys praecox) plantations under intensive management (mulching and fertilization). We examined the relationship between SOC (solid state 13C NMR) and fungal community compositions (real-time PCR, terminal restriction fragment length polymorphism, and clone library) in a chronosequence of intensively managed bamboo plantations (0, 1, 6, 10, and 15 years of stand age). The fungal community composition (internal transcribed spacer, ITS) and function (cellobiohydrolases, cbhI) and C forms in the top- (0–20) and subsoils (20–40 cm) were determined as fungi dominate cellulose (the main component of plant residues) decomposition in the soil. Soil fungal abundance (copy number of 18S rRNA) was positively correlated to O-alkyl C and aromatic C while negatively correlated to alkyl-C and carbonyl C concentrations. The alkyl C was the most influential SOC fraction on fungal community composition before intensive plantation management was applied, while O-alkyl C was the most influential C-form after more than 5 years of intensive management. The alkyl C, O-alkyl C, aromatic C and carbonyl C together explained 63.2 and 54.2% of the variations in total fungal composition in the top- and subsoils, respectively. Saprotrophic or cellulose-degrading species, mainly Mortierellales sp., Trichoderma sp. and Scheffersomyces sp., dominated the fungal community and the dominance increased with increasing plantation age (combined effects of stand age and duration of intensive management). The increased O-alkyl C concentration caused by increased plantation age explained shifts in the cbhI-containing community composition. Both the cbhI abundance and readily oxidizable C concentration increased with increasing plantation age in the topsoil but not in the subsoil. We conclude that in the intensively managed bamboo plantations changes in organic C forms were closely linked to changes in soil fungal community composition; such linkages have implications for soil nutrient cycling and C transformation in the plantation ecosystem.

Economic and ecological trade-off analysis of forest ecosystems: options for boreal forests

Intensive forest management practices for production forestry can potentially impact the sustainability of ecological functions and associated forest ecosystem services. Understanding the trade-offs between economic gains and ecological losses is critical for the sustainable management of forest resources. However, economic and ecological trade-offs are typically uncertain, vary at temporal and spatial scales, and are difficult to measure. Moreover, the methods used to quantify economic and ecological trade-offs might have conflicting priorities. We reviewed the most current published literature related to trade-off analysis between economic gains and sustainability of forest ecosystem functions and associated services, and we found that most economic and ecological trade-offs studies were conducted in tropical and temperate forests, with few having their focus on boreal forests. Analytical methods of these published studies included monetary valuation, biophysical models, optimization programming, production possibility frontier, and multi-objective optimization. This review has identified the knowledge gaps in the understanding and measurement of the economic and ecological trade-offs for the sustainable management of boreal forests. While it remains uncertain how economic activities might best maintain and support multiple ecological functions and associated services in the boreal forests, which are susceptible to climate change and disturbances, we propose the use of optimization methods employing multiple objectives. For any tool to provide sustainable and optimal forest management solutions, we propose that appropriate and robust data must be collected and analyzed.

Carbon and nitrogen pools and mineralization rates in boreal forest soil after stump harvesting

The use of forest-derived biomass has steadily increased in Finland and Sweden during the past decades leading to more intensive forest management practices in the region, such as whole-tree harvesting, both above- and belowground. Stump harvesting results in a direct removal of stump and coarse-root carbon (C) from the stand and can cause extensive soil disturbance, which has been suggested to increase C mineralization. In this study, the effects of stump harvesting on soil C and nitrogen (N) mineralization, and soil surface disturbance were studied in two different clear-felled Norway spruce (Picea abies) sites in Central Finland. The treatments were whole-tree harvesting (WTH, removal of stems and logging residues), and WTH and stump harvesting (WTH+S). Both sites, Honkola (2 stands) and Haukilahti (6 stands) were mounded. In both treatments, soil samples were taken from different soil layers down to a total depth of 20cm in the mineral soil from (i) mounds, (ii) undisturbed soil and (iii) pits. The sampling was performed 11–12years after treatments. Soil C and N mineralization rates were determined in laboratory incubation experiments. In addition, total C and N pools (gm−2) were estimated for each disturbance class and soil layer. Soil C and N pools had a tendency to be lower following stump harvesting, but no statistically significant treatment effect was detected. Stump harvesting increased soil mixing as indicated by a significant decrease in C concentration in the mound disturbance class. There was no significant effect of stump harvesting on soil C mineralization rates. A combination of mineralization rates and soil pool data showed that field C mineralization (g CO2-Cm−2yr−1) did not significantly differ between stands where stumps were removed or were retained. Further, stump harvesting did not seem to have any stimulating effect on soil CO2 efflux 11–12years after treatment.

Cradle-to-gate life cycle assessment of Eucalyptus globulus short rotation plantations in Chile

Short rotation woody crops appear to be a promising option of biomass for bioethanol production. The traditional short rotation periods for Eucalyptus globulus vary between 8 and 12 years, however intensive forest management practices and genetic improvement have increased the productivity of plantations and reduced the rotation periods up to 5 years. This study aims to assess the potential environmental impacts associated with Chilean short rotation E. globulus plantations for bioenergy production from a Life Cycle Assessment perspective. Thus, for the first time it is presented a detailed life cycle inventory and environmental assessment of a forest system in Latin America. Forest operations carried out over a lifespan of 12 years, with rotation periods of 4 years, were divided into four phases: crop establishment, harvesting, hauling and logistics infrastructure. The managed life cycle inventory included forest site data from a representative plantation dedicated to Eucalyptus chips production for energy purposes, and the inventory of the fuels production in Chile was also determined to fulfil the information requirement. The environmental profile was analysed in terms of several impact categories: climate change, ozone depletion, terrestrial acidification, freshwater y marine eutrophication, photochemical oxidant formation, human toxicity, terrestrial ecotoxicity, freshwater ecotoxicity, marine ecotoxicity, water depletion and fossil fuel depletion.The harvesting phase was the main contributor to almost all the impact categories with contributing ratios higher than 56%. Within the harvesting phase, fertilisation and forwarding were the main processes responsible for derived environmental impacts. The results in terms of climate change and terrestrial acidification were compared with those reported for Eucalyptus biomass production in European countries. The comparison was performed considering the same system boundaries and functional unit. Differences identified were related to different forest management activities carried out as well as different biomass yields. The LCA study remarked those stages where the researchers need to improve the environmental performance. The results suggested that both fertiliser dosage and fuel consumption in forest activities should be optimised in order to decrease most effectively the global environmental impacts.

Impacts of forest stand density on the biodiversity and functioning of the plant-soil interface

Global warming imposes ne wc onstraints on forest ecosystems and induces forest management adaptation. French forest policy currently advocates mor ei ntensiv et hinning so as to mitigate the increased risk of water stress from mor ef requent summer droughts. However, fe ws tudies hav ey et assessed the potential impact of these intensiv ef orest management practices on soil biodiversity, which is the subject of my thesis. The first results sho wt hat the soil food we bs tructur ei sa ffected by mor ei ntensiv et hinning. Indeed, the abundance of several soil detritivor eg roups, i.e. springtails, mites and millipedes is negatively impacted by stand density reduction. The earthworm community is also affected, as endogeic abundance increases with stand density reduction while anecic abundance decreases. This could hav ei mportant consequences in terms of litter decomposition and nutrient cycling, which ar ee ssential functions for forest soil fertility.

Mineral soil carbon and nitrogen still low three decades following clearcut harvesting in a typical Acadian Forest stand

Intensive forest management practices can alter forest soil organic matter (SOM) storage (kgCha−1) due to changes in the environmental variables that control SOM cycling and stability. Here we investigate whether SOM losses are observed three decades following clearcut harvesting in a temperate forest ecosystem that includes the deep mineral soil (to a depth of 50cm). We compared SOM stored as carbon (C) and nitrogen (N) in paired (35-year-old; 110-year-old reference) Acadian Forest sites that differed only in their time since harvest. We found lower mineral soil carbon (C) and nitrogen (N) storage (27% and 26% respectively), and lower C and N concentrations at the 35-year-old site compared with the 110-year-old reference site. Isotopic compositions of C and N through the soil profile did not provide insight into the dominant mechanisms driving SOM losses at the 35-year-old site in this study. This is the second study to document decreases in mineral soil C and N storage in a red spruce forest within the Acadian Forest Region three decades following clearcut harvesting.

Long-term intensive management effects on soil organic carbon pools and chemical composition in Moso bamboo (Phyllostachys pubescens) forests in subtropical China

Intensive forest management practices, such as fertilization, tillage, and understory removal, could markedly change the soil organic carbon (SOC) stock and labile organic carbon (C) pools. However, the combined effects of such intensive management practices on the quantity and quality of soil SOC in bamboo forests are poorly understood. The objectives of this study were to investigate the impact of long-term intensive management practices, including inorganic fertilizer application, tillage, and understory removal, on total and labile SOC pools and chemical composition of SOC in Moso bamboo (Phyllostachys pubescens) forests and to explore relationships between different soil organic C forms. We used a chronosequence approach (consisting of Moso bamboo forests with 0, 5, 10, 20, 30years of intensive management) to examine the effects of long-term intensive management on SOC storage, water soluble organic C (WSOC), hot-water soluble organic C (HWSOC), microbial biomass C (MBC), readily oxidizable C (ROC), and SOC chemistry. Our results showed that SOC stock and concentrations of WSOC, HWSOC, MBC, and ROC decreased with increasing duration under intensive management. For the chemical composition of SOC, the contents of alkyl C and carbonyl C and the alkyl C to O-alkyl C (A/O-A) ratio increased, while the contents of O-alkyl C and aromatic C and aromaticity decreased as duration under intensive management increased, suggesting that long-term intensive management changed the SOC chemical composition. Soil MBC was negatively correlated with both alkyl C content and the A/O-A ratio (P<0.01 for both), and was positively correlated with O-alkyl content (P<0.01), indicating that soil microbial population size may be partly dependent on the chemical composition of SOC. In addition, O-alkyl C content was correlated with concentrations of WSOC (P<0.05), HWSOC (P<0.01), and ROC (P<0.01), which implied that O-alkyl C might be the main C component of WSOC, HWSOC, and ROC. We conclude that long-term intensive management reduced the total and labile SOC stocks in bamboo forests and alternative management regimes should be developed to increase C sequestration of soils in intensively managed Moso bamboo forests in subtropical China.

Mineral soil carbon fluxes in forests and implications for carbon balance assessments

AbstractForest carbon cycles play an important role in efforts to understand and mitigate climate change. Large amounts of carbon (C) are stored in deep mineral forest soils, but are often not considered in accounting for global C fluxes because mineral soil C is commonly thought to be relatively stable. We explore C fluxes associated with forest management practices by examining existing data on forest C fluxes in the northeastern US. Our findings demonstrate that mineral soil C can play an important role in C emissions, especially when considering intensive forest management practices. Such practices are known to cause a high aboveground C flux to the atmosphere, but there is evidence that they can also promote comparably high and long‐term belowground C fluxes. If these additional fluxes are widespread in forests, recommendations for increased reliance on forest biomass may need to be reevaluated. Furthermore, existing protocols for the monitoring of forest C often ignore mineral soil C due to lack of data. Forest C analyses will be incomplete until this problem is resolved.

Avian Species Richness in Relation to Intensive Forest Management Practices in Early Seral Tree Plantations

BackgroundManagers of landscapes dedicated to forest commodity production require information about how practices influence biological diversity. Individual species and communities may be threatened if management practices truncate or simplify forest age classes that are essential for reproduction and survival. For instance, the degradation and loss of complex diverse forest in young age classes have been associated with declines in forest-associated Neotropical migrant bird populations in the Pacific Northwest, USA. These declines may be exacerbated by intensive forest management practices that reduce hardwood and broadleaf shrub cover in order to promote growth of economically valuable tree species in plantations.Methodology and Principal FindingsWe used a Bayesian hierarchical model to evaluate relationships between avian species richness and vegetation variables that reflect stand management intensity (primarily via herbicide application) on 212 tree plantations in the Coast Range, Oregon, USA. Specifically, we estimated the influence of broadleaf hardwood vegetation cover, which is reduced through herbicide applications, on bird species richness and individual species occupancy. Our model accounted for imperfect detection. We used average predictive comparisons to quantify the degree of association between vegetation variables and species richness. Both conifer and hardwood cover were positively associated with total species richness, suggesting that these components of forest stand composition may be important predictors of alpha diversity. Estimates of species richness were 35–80% lower when imperfect detection was ignored (depending on covariate values), a result that has critical implications for previous efforts that have examined relationships between forest composition and species richness.Conclusion and SignificanceOur results revealed that individual and community responses were positively associated with both conifer and hardwood cover. In our system, patterns of bird community assembly appear to be associated with stand management strategies that retain or increase hardwood vegetation while simultaneously regenerating the conifer cover in commercial tree plantations.