Impact Of Forest Harvesting Research Articles

Impacts of forest harvesting on mercury concentrations and methylmercury production in boreal forest soils and stream sediment

Methylmercury (MeHg) is the most neurotoxic and bioaccumulative form of mercury (Hg) present in the terrestrial and aquatic food sources of boreal ecosystems, posing potential risks to wildlife and human health. Harvesting impacts on Hg methylation and MeHg concentrations in forest soils and stream sediment are not fully understood. In this study, a field investigation was carried out in 4 harvested and 2 unharvested boreal forest watersheds, before and after harvest, to better understand impacts on Hg methylation and MeHg concentration in soils and stream sediment, including their responses to different forest management practices. Changes in total Hg (THg) and MeHg concentrations, first-order potential rate constants for Hg methylation and MeHg demethylation (Kmeth and Kdemeth) as well as total carbon content and carbon-to-nitrogen ratio post-harvest in upland, wetland and riparian soils and stream sediment were assessed and compared. Increases in MeHg production were minimal in upland, wetland or riparian soils after harvest. Sediment in streams with minor buffer protection (∼3 m), greater fractions (>75%) of harvested watershed area and more road construction had significantly increased THg and MeHg concentrations, %-MeHg, Kmeth and total carbon content post-harvest. From these patterns, we infer that inputs of carbon and inorganic Hg into harvest-impacted stream sediment are likely sourced from the harvested upland areas and stimulate in situ MeHg production in stream sediment. These findings indicate the importance of stream sediment as potential MeHg pools in harvested forest watersheds. The findings also demonstrate that forest management practices aiming to mitigate organic matter and Hg inputs to streams can effectively alleviate harvesting impacts on Hg methylation and MeHg concentrations in stream sediment.

Long-term effect of forest harvesting on boreal species assemblages under climate change

Logging is the main human disturbance impacting biodiversity in forest ecosystems. However, the impact of forest harvesting on biodiversity is modulated by abiotic conditions through complex relationships that remain poorly documented. Therefore, the interplay between forest management and climate change can no longer be ignored. Our aim was to study the expected long-term variations in the assemblage of bird and beetle communities following modifications in forest management under different climate change scenarios. We developed species distribution models to predict the occurrence of 88 species of birds and beetles in eastern Canadian boreal forests over the next century. We simulated three climate scenarios (baseline, RCP4.5 and RCP8.5) under which we varied the level of harvesting. We also analyzed the regional assemblage dissimilarity by decomposing it into balanced variations in species occupancy and occupancy gradient. We predict that forest harvesting will alter the diversity by increasing assemblage dissimilarity under all the studied climate scenarios, mainly due to species turnover. Species turnover intensity was greater for ground-dwelling beetles, probably because they have lower dispersal capacity than flying beetles or birds. A good dispersal capacity allows species to travel more easily between ecosystems across the landscape when they search for suitable habitats after a disturbance. Regionally, an overall increase in the probability of occupancy is projected for bird species, whereas a decrease is predicted for beetles, a variation that could reflect differences in ecological traits between taxa. Our results further predict a decrease in the number of species that increase their occupancy after harvest under the most severe climatic scenario for both taxa. We anticipate that under severe climate change, increasing forest disturbance will be detrimental to beetles associated with old forests but also with young forests after disturbances.

Chainsaw part damage of harvesting teak forest in Madiun East Java, Indonesia

Forest harvesting has to be a concern for productivity, the operator's safety, and the environmental impact of forest harvesting. Chainsaw is commonly used for forest harvesting in Java, Indonesia. To increase the harvesting productivity, the operator has to maintain their chainsaw. Part of the chainsaw is often damaged in the harvesting process, affecting the productivity of felling the trees. This study analyzes the damage to parts from chainsaws in teak forest harvesting. The research location was in a forest area of Perhutani Company in Madiun East Java. The result shows that all ten chainsaws had damage to their parts components. The piston was the engine component which damaged in all the ten chainsaws. The body components such as the front handle, muffler, and on-off switch were damaged by all ten chainsaws. We observed that the chainsaw operator could not maintain the chainsaw well.

Способы защиты лесных почв в ходе лесозаготовительных работ (обзор)

Public opinion has become increasingly critical of current logging methods and technologies, and there is a demand for standards to guide the operations of environmentally impactful industries. For many years, numerous researchers have studied the impact of logging on forest soils, revealing that there is a high risk of damaging forest soil during forest operations and terrain transport. Here we analyse and review a total of 105 publications in this area. This large body of work demonstrates the scientific interest that this field has attracted. Despite this, important areas of uncertainty concerning the impact of forest harvesting still remain. In particular, changes in soil conditions can affect soil properties in ways that are not well understood, with possible impacts on the physical, chemical, and biological properties of soils as well as the structure of the soil cover. While it is difficult to fully eliminate the negative impact of forest operations on forest soils, their adverse environmental consequences should be minimised because soil plays a vital role in tree regeneration and helps determine the productivity of future forest stands. Some of the most frequently cited measures and effective technological solutions to minimize damage to forest soils involve taking terrain and different technical solutions into account when organising logging operations. Potentially helpful technical solutions include selecting machines and mechanisms suitable for the site conditions, using larger and/or low-pressure tyres, using tyre pressure control, using anti-skid tracks, using track belts, meliorating wet areas, and using logging machinery incorporating global positioning systems and geographic information systems. Planning measures that can help minimize soil damage include choosing a suitable wood harvesting system and technology, accounting for seasonal factors when planning logging operations, planning networks of roads and trails in advance, leaving wood residues or mats on soil surface, training forest specialists, and reducing the number of machine passes over skid trails and strip roads. Despite active interest in applying sparing methods of wood harvesting, uptake of measures designed to reduce negative impacts on forest soils after logging has been limited. This may be due to a lack of scientific and technical information and the high cost of implementing best management practices. Moreover, economic factors and production plans may require wood harvesting throughout the year, irrespective of conditions. For citation: Ilintsev A.S., Nakvasina E.N., Högbom L. Methods of Protection Forest Soils during Logging Operations (Review). Lesnoy Zhurnal [Russian Forestry Journal], 2021, no. 5, pp. 92–116. DOI: 10.37482/0536-1036-2021-5-92-116

Both Forest Harvesting and Hydropower Dams Yielded Negative Impact on Low Flow Regimes in the Zagunao River Watershed, Southwest China

Forest harvesting and hydropower dams can significantly affect flow regimes (magnitude, timing, duration, frequency, and variability), resulting in changes in degraded aquatic ecosystems and unstable water supply. Despite numerous studies on the effects of forest harvesting on mean flows, the impact of forest harvesting on flow regimes has been less investigated. A great difficulty lies in separating the hydrological effect of forest harvesting from that of climate variability and other watershed disturbances such hydropower dams. In this study, the Upper Zagunao River watershed (2242 km2) was selected as an example to provide a quantitative assessment of the effects of forest harvesting and hydropower dams on low flow regimes. The key findings include: (1) Forest harvesting led to a significant reduction in the magnitude and return period of low flows, and a significant increment in the variability and duration of low flows; (2) the recovery of low flow regimes occurred 40 years after forest harvesting as forest recovery processed; and (3) hydropower dams caused significant impact on all components of low flow regimes, e.g., a reduction in the magnitude, return period, and timing of low flows, and an increment in the variability and duration of low flows. Our findings highlight the negative impact of both forest harvesting and hydropower dams on low flow regimes in the Upper Zagunao River watershed. A watershed management strategy for offsetting the negative effect of hydropower dams on low flow regimes by restoring hydrological functions of subalpine forests is highly recommended in subalpine watersheds of the Upper Yangtze River.

Impact of timber harvesting on carbon storage in montane forests of central Mexico

Cut stumps are the legacy of forest harvesting and allow for the estimation of carbon loss from the ecosystem. The objective of this study was to estimate aboveground carbon storage and the impact of forest harvesting based on measurements of cut stumps in pine forests within the Area de Proteccion de Flora y Fauna Nevado de Toluca (APFFNT) in the state of Mexico. A total of 1621 circular 0.1-ha sampling plots were established in a 12,924 ha pine forest (1.25% sampling intensity). Biomass was calculated using conventional volumetric equations incorporating species-specific wood densities. Aboveground carbon storage in the biomass was stratified by forest type including dense forest (≥ 336 trees), semi-dense forest ( 150 trees), fragmented forest ( 20 trees), and stands with isolated trees (< 20 trees). In the 12, 924 ha of forest dominated by Pinus hartwegii, 1,695,004 MgC was contained in aboveground biomass. Data on forest harvesting obtained by analysis of recent cut stumps allowed for the estimation of the removal of 42,701 MgC. In addition, we accounted for carbon in wind thrown trees of 14,904 MgC, some of which were removed over time in harvests. Total loss of carbon from the forest corresponded to 211,218 MgCO2 per year. In the APFFNT, forests dominated by pine with high biomass (P. hartwegii and P. montezumae) are being replaced by those with lower biomass (Alnus jorullensis). Changes in these communities will result in lower carbon capture in the APFFNT.

Forest harvesting impacts on microclimate conditions and sediment transport activities in a humid periglacial environment

Abstract. Sediment transport activities in periglacial environments are controlled by microclimate conditions (i.e., air and ground temperatures, throughfall), which are highly affected by vegetation cover. Thus, there is the possibility that forest harvesting, the most dramatic change to vegetation cover in mountain areas, may severely impact sediment transport activities in periglacial areas (i.e., soil creep, dry ravel). In this study, we investigated changes in sediment transport activities following forest harvesting in steep artificial forests located in a humid periglacial area of the southern Japanese Alps. In the southern Japanese Alps, rainfall is abundant in summer and autumn, and winter air temperatures frequently rise above and fall below 0∘. Our monitoring by time lapse cameras revealed that gravitational transport processes (e.g., frost creep and dry ravel) dominate during the freeze–thaw season, while rainfall-induced processes (surface erosion and soil creep) occur during heavy rainfall seasons. Canopy removal by forest harvesting increased the winter diurnal ground surface temperature range from 2.7 to 15.9 ∘C. Forest harvesting also increased the diurnal range of net radiation and ground temperature, and decreased the duration of snow cover. Such changes in the microclimate conditions altered the type of winter soil creep from frost creep to diurnal needle-ice creep. Winter creep velocity of ground surface sediment in the harvested site (&gt; 2 mm day−1 on the days with frost heave) was significantly higher than that in the non-harvested site (generally &lt; 1 mm day−1). Meanwhile, sediment flux on the hillslopes, as observed by sediment traps, decreased in the harvested site. Branches of harvested trees left on the hillslopes captured sediment moving downslope. In addition, the growth of understories after harvesting possibly reduced surface erosion. Consequently, removal of the forest canopy by forest harvesting directly impacts the microclimate conditions (i.e., diurnal range of ground temperature and net radiation, duration of snow cover) and increases frequency and velocity of periglacial soil creep, while sediment flux on hillslopes is decreased by branches left on the hillslopes and recovery of understories. The impact of forest harvesting on sediment transport activity is seasonally variable in humid periglacial areas, because microclimate conditions relevant to both freeze–thaw processes and precipitation-induced processes control sediment transport.

The application of an integrated biogeochemical model to simulate dynamics of vegetation, hydrology and nutrients in soil and streamwater following a whole-tree harvest of a northern hardwood forest

Understanding the impacts of clear-cutting is critical to inform sustainable forest management associated with net primary productivity and nutrient availability over the long-term. Few studies have rigorously tested model simulations against field measurements which would provide more confidence in efforts to quantify logging impacts over the long-term. The biogeochemical model, PnET-BGC has been used to simulate forest production and stream chemistry at the Hubbard Brook Experimental Forest (HBEF), New Hampshire, USA. Previous versions of PnET-BGC could accurately simulate the longer-term biogeochemical response to harvesting, but were unable to reproduce the marked changes in stream NO3− immediately after clear-cutting which is an important impact of forest harvesting. Moreover, the dynamics of nutrients in major pools including mineralization and plant uptake were poorly predicted. In this study, the model was modified and parametrized allowing for a lower decomposition rate during the earlier years after the clear-cut and increased NH4+ plant uptake with the regrowth of new vegetation to adequately reproduce hydrology, aboveground forest biomass, and soil solution and stream water chemistry in response to a whole-tree harvest of a northern hardwood forest watershed (W5) at the HBEF. Modeled soil solution and stream water chemistry successfully captured the rapid recovery of leaching nutrients to pre-cut levels within four years after the treatment. The model simulated a substantial increase in aboveground net primary productivity (NPP) from around 36% to 97% of pre-cut aboveground values within years 2 to 4 of the cut, which closely reproduced the measured values. The projected accumulation of aboveground biomass 70 years following the harvest was almost 190 t ha−1, which is close to the pre-cut measured value. A first-order sensitivity analysis showed greater sensitivity of projections of the model outputs for the mature forest than the strongly aggrading forest.

Stream Mercury Export in Response to Contemporary Timber Harvesting Methods (Pacific Coastal Mountains, Oregon, USA).

Land-use activities can alter hydrological and biogeochemical processes that can affect the fate, transformation, and transport of mercury (Hg). Previous studies in boreal forests have shown that forestry operations can have profound but variable effects on Hg export and methylmercury (MeHg) formation. The Pacific Northwest is an important timber producing region that receives large atmospheric Hg loads, but the impact of forest harvesting on Hg mobilization has not been directly studied and was the focus of our investigation. Stream discharge was measured continuously, and Hg and MeHg concentrations were measured monthly for 1.5 years following logging in three paired harvested and unharvested (control) catchments. There was no significant difference in particulate-bound Hg concentrations or loads in the harvested and unharvested catchments which may have resulted from forestry practices aimed at minimizing erosion. However, the harvested catchments had significantly higher discharge (32%), filtered Hg concentrations (28%), filtered Hg loads (80%), and dissolved organic carbon (DOC) loads (40%) compared to forested catchments. MeHg concentrations were low (mostly <0.05 ng L-1) in harvested, unharvested, and downstream samples due to well-drained/unsaturated soil conditions and steep slopes with high energy eroding stream channels that were not conducive to the development of anoxic conditions that support methylation. These results have important implications for the role forestry operations have in affecting catchment retention and export of Hg pollution.

Intensive forest harvesting increases susceptibility of northern forest soils to carbon, nitrogen and phosphorus loss

Abstract Understanding the impact of forest harvesting is critical to sustainable forest management, yet there remains much uncertainty regarding how harvesting affects soil carbon (C), nitrogen (N) and phosphorus (P) dynamics. Here, we conducted a global meta‐analysis of 808 observations from 49 studies to test the effects of harvesting on the stocks and concentrations of soil C, N and P and C:N:P ratios relative to uncut control stands. With all harvesting intensities combined, C stock was unaffected by harvesting in either the forest floor or mineral soil, while harvesting reduced forest floor [C], [N] and [P] and C:N ratio, increased the mineral soil [C] and C:N ratio, but reduced mineral soil N stock. The impacts of harvesting on forest floor C and N stocks, C:P and N:P and mineral soil [C] and [N] changed from no effects by partial, stem‐only and whole‐tree harvesting (WTH) to significantly negative effects by the harvesting coupled with fire. Stem‐only and WTH similarly reduced forest floor [P]. The negative effects of harvesting were most pronounced in conifer stands. Soil [C], [N] and C:N decreased with time since harvesting, but soil [P] did not, resulting in an increase in forest floor N:P. Synthesis and applications. Our findings highlight the importance of harvest intensity and rotation length on long‐term soil nutrient availability when managing forests. Furthermore, the lag in the recovery of phosphorus concentration following harvesting may indicate a decoupling of the phosphorus cycle from those of carbon and nitrogen, and a potential concern in managed forests.

The impact of forest harvesting on caribou–moose–wolf interactions decreases along a latitudinal gradient

Human activities can impact animal communities by altering species interactions. The influence of forest harvesting on the interaction between threatened boreal caribou, moose, and wolves constitutes a classic example. When conifer forests are logged, clear-cuts are colonized by deciduous vegetation that provides high-quality food for moose. Subsequent changes in wolf distribution alter predation risk for caribou. Given that primary productivity varies along latitudinal gradients, the effects of logging on moose-caribou-wolf interactions could also vary moving northwards. Empirical evidence, however, is lacking and current recommendations for caribou conservation are fixed over space. We assessed whether the impact of logging activities on caribou-moose-wolf interactions varies with latitude. We estimated deciduous vegetation availability from satellite imagery, and followed all three species with GPS collars to evaluate their habitat selection. We found that the availability of deciduous vegetation in logged stands decreased along a 400-km latitudinal gradient. The probability of caribou occurrence remained low in clear-cuts, regardless of deciduous vegetation availability. Moose and wolves increased their selection for clear-cuts as they contained more deciduous vegetation. Accordingly, the relative co-occurrence probability of moose and wolves was strongly associated with clear-cuts at low latitudes, but weakly so at high latitudes. Clear-cuts should therefore attract moose and wolves more strongly to prime boreal caribou habitat at lower latitudes, and caribou predation risk should follow similar geographical patterns. Conservation planning should account for geographical patterns in the risk faced by threatened populations because the effectiveness of strategies developed from average patterns can decrease over space, in consistent manner.

Impacts of forest harvesting on mobilization of Hg and MeHg in drained peatland forests on black schist or felsic bedrock.

Forest harvesting, especially when intensified harvesting method as whole-tree harvesting with stump lifting (WTHs) are used, may increase mercury (Hg) and methylmercury (MeHg) leaching to recipient water courses. The effect can be enhanced if the underlying bedrock and overburden soil contain Hg. The impact of stem-only harvesting (SOH) and WTHs on the concentrations of Hg and MeHg as well as several other variables in the ditch water was studied using a paired catchment approach in eight drained peatland-dominated catchments in Finland (2008-2012). Four of the catchments were on felsic bedrock and four on black schist bedrock containing heavy metals. Although both Hg and MeHg concentrations increased after harvesting in all treated sites according to the randomized intervention analyses (RIAs), there was only a weak indication of a harvest-induced mobilization of Hg and MeHg into the ditches. Furthermore, no clear differences between WTHs and SOH were found, although MeHg showed a nearly significant difference (p = 0.06) between the harvesting regimes. However, there was a clear bedrock effect, since the MeHg concentrations in the ditch water were higher at catchments on black schist than at those on felsic bedrock. The pH, suspended solid matter (SSM), dissolved organic carbon (DOC), and iron (Fe) concentrations increased after harvest while the sulfate (SO4-S) concentration decreased. The highest abundances of sulfate-reducing bacteria (SRB) were found on the sites with high MeHg concentrations. The biggest changes in ditch water concentrations occurred first 2years after harvesting.

Reducing the Impact of Forest Harvesting on the Vancouver Island Tourism Industry

British Columbia forests have traditionally been managed for timber production. However, the increasing importance of nature-based tourism within the province means that forests also have significant value as a tourism resource. This can lead to conflicts between the forestry and tourism industries. This article examines tourism and forestry interests on Vancouver Island and discusses ways that forests could be managed to reduce negative impacts to the tourism industry. Eighteen semi-structured interviews were conducted with forestry and tourism industry professionals on Vancouver Island and elsewhere in British Columbia. Findings suggest that visual impacts associated with forestry can negatively impact tourism. It also appears that forestry receives a much higher priority than tourism when it comes to forest management, despite the vital importance of the tourism industry to the Vancouver Island economy. Displeasure over the lack of communication requirements between the forest industry and other stakeholders was also documented. The implementation of formal agreements between the two industries may potentially reduce conflicts between these two industries on Vancouver Island. Identification and special management of highly valuable tourism areas may also provide benefits to the Vancouver Island tourism industry.

Impact of forest harvesting on water quality and fluorescence characteristics of dissolved organic matter in eastern Canadian Boreal Shield lakes in summer

Abstract. Forestry activities in the Canadian Boreal region have increased in the last decades, raising concerns about their potential impact on aquatic ecosystems. Water quality and fluorescence characteristics of dissolved organic matter (DOM) were measured over a 3-year period in eight eastern Boreal Shield lakes: four lakes were studied before, 1 and 2 years after forest harvesting (perturbed lakes) and compared with four undisturbed reference lakes (unperturbed lakes) sampled at the same time. ANOVAs showed a significant increase in total phosphorus (TP) in perturbed lakes when the three sampling dates were considered and in DOC concentrations when considering 1 year before and 1 year after the perturbation only. At 1 year post-clear cutting DOC concentrations were about 15 % greater in the perturbed lakes at ~ 15 mgC L−1 compared to 12.5 mgC L−1 in the unperturbed lakes. In contrast, absorbance and fluorescence measurements showed that all metrics remained within narrow ranges compared to the range observed in natural waters, indicating that forest harvesting did not affect the nature of DOM characterized with spectroscopic techniques. These results confirm an impact of forestry activities 1 year after the perturbation. However, this effect seems to be mitigated 2 years after, indicating that the system shows high resilience and may be able to return to its original condition in terms of water quality parameters assessed in this study.

Impact of forest harvesting on trophic structure of eastern Canadian Boreal Shield lakes: insights from stable isotope analyses.

Perturbations on ecosystems can have profound immediate effects and can, accordingly, greatly alter the natural community. Land-use such as forestry activities in the Canadian Boreal region have increased in the last decades, raising concerns about their potential impact on aquatic ecosystems. The objective of this study was to evaluate the impact of forest harvesting on trophic structure in eastern Canadian Boreal Shield lakes. We measured carbon and nitrogen stable isotopes values for aquatic primary producers, terrestrial detritus, benthic macroinvertebrates, zooplankton and brook trout (Salvelinus fontinalis) over a three-year period in eight eastern Boreal Shield lakes. Four lakes were studied before, one and two years after forest harvesting (perturbed lakes) and compared with four undisturbed reference lakes (unperturbed lakes) sampled at the same time. Stable isotope mixing models showed leaf-litter to be the main food source for benthic primary consumers in both perturbed and unperturbed lakes, suggesting no logging impact on allochthonous subsidies to the littoral food web. Brook trout derived their food mainly from benthic predatory macroinvertebrates in unperturbed lakes. However, in perturbed lakes one year after harvesting, zooplankton appeared to be the main contributor to brook trout diet. This change in brook trout diet was mitigated two years after harvesting. Size-related diet shift were also observed for brook trout, indicating a diet shift related to size. Our study suggests that carbon from terrestrial habitat may be a significant contribution to the food web of oligotrophic Canadian Boreal Shield lakes. Forest harvesting did not have an impact on the diet of benthic primary consumers. On the other hand, brook trout diet composition was affected by logging with greater zooplankton contribution in perturbed lakes, possibly induced by darker-colored environment in these lakes one year after logging.

Carbon density and anthropogenic land-use influences on net land-use change emissions

Abstract. We examine historical and future land-use emissions using a simple mechanistic carbon-cycle model with regional and ecosystem specific parameterizations. We use the latest gridded data for historical and future land-use changes, which includes estimates for the impact of forest harvesting and secondary forest regrowth. Our central estimate of net terrestrial land-use change emissions, exclusive of climate–carbon feedbacks, is 250 GtC over the last 300 yr. This estimate is most sensitive to assumptions for preindustrial forest and soil carbon densities. We also find that land-use change emissions estimates are sensitive to the treatment of crop and pasture lands. These sensitivities also translate into differences in future terrestrial uptake in the RCP (representative concentration pathway) 4.5 land-use scenario. The estimate of future uptake obtained here is smaller than the native values from the GCAM (Global Change Assessment Model) integrated assessment model result due to lower net reforestation in the RCP4.5 gridded land-use data product.

Lessons learned from 12 years of ecological research on partial cuts in black spruce forests of northwestern Québec

Multi-cohort management that creates or maintains an uneven structure within forest stands has been widely advocated as a means to attenuate the impact of forest harvesting. An experimental network was put in place in black spruce forests of northwestern Québec to test this assertion. Here we synthesize the biodiversity results in two main lessons: (1) at least 40% to 60% retention of pre-harvest basal area was required to maintain pre-harvest conditions for most species groups; (2) partial harvests showed the potential to be efficient deadwood delivery systems. In addition to these two main general conclusions, we emphasise that future research should examine whether partial harvest may be able to advance forest succession.

A chronsequential approach to investigating microbial community shifts following clearcutting in Boreal Plain forest soils

Impacts of forest harvesting are often assessed in short-term studies that ignore the longer term changes associated with the disturbance. A chronosequence approach was taken to investigate changes in microbial community size and composition over ∼20 years post-harvest in lodgepole pine ( Pinus contorta Douglas ex Loudon) stands of the Boreal Plain. The LFH and mineral Ae horizons of Orthic Gray Luvisolic soils were sampled in six cutblocks, aged 1–19 years since harvest, in 2009 and 2010. Changes in microbial communities were assessed using phospholipid fatty acid analysis (PLFA) and 16S rDNA analysis. Physical and chemical soil parameters were measured to delineate microsite changes impacting microbial community shifts. Total microbial biomass (PLFA) was unaffected by harvesting disturbance, although fungal biomass was significantly larger in the oldest cutblock of the chronosequence. Microbial community composition did, however, differ between younger and older cutblocks as indicated by both lipid PLFA and 16S rDNA fingerprinting techniques. Forest soil microbial communities subject to clearcutting were observed to shift in overall community composition while remaining consistent in overall community size. The shift in community composition, which occurred in concert with the maintenance of biomass, indicated that the microbial community adapted sufficiently to the new post-harvest microsite conditions.

Framework for assessing the impact of human activities on the environment: the impact of forest harvesting and petroleum drilling on habitat of moose (Alces alces) and marten (Martens americana)

The environmental changes induced by projects occurring in an area are evaluated by cumulative impact assessments (CIA), which consider the consequences of multiple projects, each insignificant on its own, yet important when evaluated collectively. When future human activities are of interest, the proposed activities are included in CIA using an analytical platform that can supply precise predictions but with asymptotically null accuracy. To compensate for the lack of accuracy we propose a shift in the paradigm governing CIA. The paradigm shift advocates a change in the focus of CIA investigations from the detailed analysis of one unlikely future to the identification of patterns describing the future changes in the environment. To illustrate the paradigm shift, a set of 144 possible and equally likely futures were developed and used to identify the potential impacts of forest harvesting and petroleum drilling on the habitat of moose and marten. The univariate and multivariate analysis of two measures of habitat, namely average habitat suitability index (HSI) and surface of the stands with HSI >0.5, revealed at least three distinct periods in the next 100 years. Multivariate analysis also showed that habitat quality is of immediate importance and marten is sensitive during the first third of the century. Our findings indicate that the spatial and temporal arrangement of the human disturbances could be more important than the magnitude of the disturbance. The attributes associated with significant environmental changes are harvesting age and the investigated environmental elements of an ecosystem, in this case the species habitat.

An analytical platform for cumulative impact assessment based on multiple futures: The impact of petroleum drilling and forest harvesting on moose ( Alces alces) and marten ( Martes americana) habitats in northeastern British Columbia

The combined influence on the environment of all projects occurring in a single area is evaluated through cumulative impact assessments (CIA), which consider the consequences of multiple projects, each insignificant on its own, yet important when evaluated collectively. Traditionally, future human activities are included in CIA using an analytical platform, commonly based on complex models that supply precise predictions but with reduced accuracy. To compensate for the lack of accuracy in current CIA approaches, we propose a shift in the paradigm governing CIA. The paradigm shift involves a change in the focus of CIA investigations from the detailed analysis of one unlikely future to the identification of the patterns describing multiple potential future changes in the environment. To illustrate the approach, a set of 144 possible and equally likely futures were developed that aimed to identify the potential impacts of forest harvesting and petroleum drilling on the habitat suitability of moose and marten in northeast British Columbia, Canada. The evolution of two measures of habitat suitability (average habitat suitability index and surface of the stands with habitat suitability index >0.5) revealed that the human activities could induce cycles in the habitat dynamics of moose and marten. The planning period of 100 years was separated into three distinct periods following a sinusoidal pattern (i.e., increase – constant – decrease in the habitat suitability measures). The attributes that could induce significant changes in the assessment of environment are the choice of harvesting age and species.