Effects Of Timber Harvesting Research Articles

White-tailed deer population dynamics in a multipredator landscape shaped by humans.

Large terrestrial mammals increasingly rely on human-modified landscapes as anthropogenic footprints expand. Land management activities such as timber harvest, agriculture, and roads can influence prey population dynamics by altering forage resources and predation risk via changes in habitat, but these effects are not well understood in regions with diverse and changing predator guilds. In northeastern Washington state, USA, white-tailed deer (Odocoileus virginianus) are vulnerable to multiple carnivores, including recently returned gray wolves (Canis lupus), within a highly human-modified landscape. To understand the factors governing predator-prey dynamics in a human context, we radio-collared 280 white-tailed deer, 33 bobcats (Lynx rufus), 50 cougars (Puma concolor), 28 coyotes (C. latrans), and 14 wolves between 2016 and 2021. We first estimated deer vital rates and used a stage-structured matrix model to estimate their population growth rate. During the study, we observed a stable to declining deer population (lambda = 0.97, 95% confidence interval: 0.88, 1.05), with 74% of Monte Carlo simulations indicating population decrease and 26% of simulations indicating population increase. We then fit Cox proportional hazard models to evaluate how predator exposure, use of human-modified landscapes, and winter severity influenced deer survival and used these relationships to evaluate impacts on overall population growth. We found that the population growth rate was dually influenced by a negative direct effect of apex predators and a positive effect of timber harvest and agricultural areas. Cougars had a stronger effect on deer population dynamics than wolves, and mesopredators had little influence on the deer population growth rate. Areas of recent timber harvest had 55% more forage biomass than older forests, but horizontal visibility did not differ, suggesting that timber harvest did not influence predation risk. Although proximity to roads did not affect the overall population growth rate, vehicle collisions caused a substantial proportion of deer mortalities, and reducing these collisions could be a win-win for deer and humans. The influence of apex predators and forage indicates a dual limitation by top-down and bottom-up factors in this highly human-modified system, suggesting that a reduction in apex predators would intensify density-dependent regulation of the deer population owing to limited forage availability.

Cut vs. fire: a comparative study of the temporal effects of timber harvest and wildfire on ecological indicators of the boreal forest

ContextLarge-scale natural disturbances are crucial drivers of ecosystem function and composition for many forested ecosystems. In the last century, the prevalence of anthropogenic disturbances has increased across Canada’s boreal forest. Habitat disturbance from timber harvest and wildfire is linked to declines of boreal species, including woodland caribou (Rangifer tarandus caribou).ObjectivesWe tested how disturbances influenced the recovery trajectory of ecological indicators of timber, biodiversity, and wildlife habitat through time following timber harvest and wildfire across the boreal forest of Alberta, Canada.MethodsDuring 2021 and 2022, we collected field data from 251 timber harvested and 264 burned stands (0–40 years since disturbance), as well as 256 older forest stands used by caribou (> 40 years since disturbance). Field data included metrics of stand attributes (e.g., basal area, stems per hectare), coarse woody debris (CWD), and abundance of forage for caribou, moose (Alces americanus), and bears (black bear: Ursus americanus, grizzly bear: Ursus arctos).ResultsBasal area of trees and stems per hectare recovered more quickly in timber harvest sites when compared to wildfire sites, but as time since disturbance increased there were no differences in these attributes among timber harvest, wildfire, and caribou use sites. CWD was greatest in recently burned sites, but declined over time to be similar in quantity as in harvested stands and older forest stands. Terrestrial lichens, important forage for caribou, were most abundant in the older caribou use sites, whereas forage for moose and bears, including shrubs, was most abundant in younger timber harvest and wildfire sites.ConclusionsOur results demonstrate that timber harvesting may result in a quicker development of timber volume when compared to wildfire. However, this anthropogenic disturbance is less advantageous for the development of caribou habitat.

Modeling instream temperature from solar insolation under varying timber harvesting intensities using RPAS laser scanning

Stream temperatures are influenced by the amount of solar insolation they receive. Increasing stream temperatures associated with climate warming pose detrimental health risks to freshwater ecosystems. In British Columbia (BC), Canada, timber harvesting along forested streams is managed using riparian buffer zones of varying widths and designations. Within buffer zones, depending on distance from the stream, selective thinning may be permitted or harvest may be forbidden. In this study, we used airborne laser scanning (ALS) point cloud data acquired via a remotely piloted aircraft system (RPAS) to derive forest canopy characteristics that were then used to estimate daily incoming summer and fall solar insolation for five stream reaches in coastal conifer-dominated temperate forests in Vancouver Island, BC, Canada. We then examined empirical relationships between estimated insolation and actual instream temperature measurements. Based on these empirical relationships, the potential effects of timber harvest on instream temperatures were simulated by comparing scenarios of different riparian forest harvest intensities. Our results indicated that modeled solar insolation explained 43–90 % of the variation in observed stream reach temperatures, and furthermore, when a single cold-water stream reach was excluded explained an overall 81 % of variation. Simulated harvesting scenarios generally projected increases in maximum stream reach temperatures 1–2 °C in summer and early fall months. However, in a full clearcut scenario (i.e. where all trees were removed), maximum stream reach temperatures increased as much as 5.8 °C. Our results emphasize the importance of retaining riparian vegetation for the maintenance of habitable temperatures for freshwater-reliant fish with thermal restrictions. In addition, we demonstrate the feasibility of RPAS-based monitoring of stream reach shading and canopy cover, enabling detailed assessment of environmental stressors faced by fish populations under climate warming.

Implications of community forest management for the conservation of the genetic diversity of big-leaf mahogany (Swietenia macrophylla King, Meliaceae) in the Maya Biosphere Reserve, Petén, Guatemala

Community Forest Management in the Maya Biosphere Reserve (MBR; Petén, Guatemala) has been recognized internationally for yielding forest conservation and socioeconomic benefits. However, the effect of current timber harvesting practices on the genetic diversity of timber species populations has not previously been documented. This study assessed the effects of timber harvesting on the genetic diversity and viability of regeneration of the most commercially important timber species in the MBR: big-leaf mahogany (Swietenia macrophylla King). Trees and seeds were sampled for two consecutive years in two Forest Management Units of the Multiple Use Zone (MUZ) of the MBR: Cruce a la Colorada and Carmelita. We correlated genetic diversity parameters (as measured using nuclear microsatellites) with seed germination percentages and compared genetic diversity of adults and seeds in stands that had been affected by timber harvesting and those that had not. We found a significant correlation between seed germination percentages (81–83%) and observed heterozygosity (rho=0.27), confirming that genetic diversity is important to regeneration success. No significant differences were found in allelic richness (AR), expected and observed heterozygosity (HE and HO), or inbreeding (FIS), between adults and seeds in harvested vs. undisturbed stands; or before and after timber harvesting. We found low inbreeding levels (FIS=0.040–0.094), low biparental inbreeding (0–0.01), and high outcrossing rates (0.925–0.970) in the populations of S. macrophylla analyzed. Our study therefore provides evidence that genetic diversity in big-leaf mahogany populations was not diminished by one cutting cycle under current practices of community forest management in the MUZ of the MBR.

Effect of timber removal on the total nutrient fluxes from a freshwater-supplying forested watershed.

Effects of 18% thinning on nutrient fluxes were investigated in a broadleaf forest. Streamflow and suspended sediment were sampled during the calibration and treatment periods for the treatment and control watersheds to determine total nutrient fluxes through bedload sediment and runoff. Streamflow was measured, and water samples were collected from the streams of the watersheds. The volume of the bedload deposited in both weirs' pools was measured, and sediment deposits were sampled at the ends of the calibration and treatment periods. Water and sediment samples were analyzed for calcium (Ca2+ ), magnesium (Mg2+ ), Kjeldahl nitrogen (KN), sodium (Na+ ), potassium (K+ ), iron (Fe3+ ), and sulfur (S2- ). Results showed that there was only a significant increase in KN loss from 0.01 kg/ha to 0.10kg/ha and from 0.04 kg/ha to 2.41 kg/ha in the second and the third post-treatment years, respectively (P < 0.05). Thinning was not intensive to change nutrient outflow in the study site. PRACTITIONER POINTS: The 18% thinning was not intensive enough to increase the total nutrient flux, deteriorate water chemical quality, and hence threaten aquatic life in the stream water. Significant increases were found only in KN outflow after timber removal. If there is no information about the effect of timber harvest on nutrient loss in a specific watershed, the application of evenly distributed low-intensity timber harvest may be a good option to protect stream water quality in forested watersheds. Further investigations are needed about the effects of various timber harvest intensities on physical water quality (odor, color, turbidity, taste, temperature, etc.) and biological characteristics (population and biodiversity of aquatic organisms) of the stream water for making better water management plans.

Multi-year, post-harvesting impact assessment in a neotropical secondary Atlantic Forest

Subject to overexploitation in the past centuries, the Atlantic Forest is subject to very rigorous protection rules. However, the law is a controversial issue since landowners are not compensated for the limited choice of land use possibilities. We believe that, alternatively to a general timber harvest ban, sustainable forest management of the Atlantic Forest has the potential to generate income for the landowners while sustaining important ecological functions of the forest. Such choice would require better understanding of the potential effects of timber harvesting on the forest ecosystem and on species composition and succession over time. In this context, we assessed the harvesting impact of a conventional harvesting method (CM) and compared it to an alternative harvesting method (AM) in three different stands (stands A, B and C) of a secondary forest fragment in southern Brazil. Results from three comprehensive forest inventories over a period of two years were used to assess the timber harvesting impact. Measurements of species composition (i.e., number of species, life form, ecological group), forest structure (i.e., density, basal area, DBH, volume) and saplings density formed the basis of the impact assessment. The inventories were carried out before, immediately after and two years after harvesting. Intensities of damage on remnant trees immediately after harvesting and two years after harvesting were also measured. Before harvesting, a total of 114 tree species (trees, tree fern and palm tree) belonging to 49 families were identified in the study site’s three research stands. Palm trees and secondary species, such as Euterpe edulis, represented the majority of recruited individuals (DBH ≥ 5 cm) two years after harvesting. However, new saplings (DBH ≤ 5 cm) after two years were mainly pioneer woody tree species, such as Cecropia glaziovii and Schizolobium parahyba. On average, AM reduced damage to saplings by 5%. Most of the damages caused by CM were moderate to severe, while AM caused light to moderate damages. Binary logistic regression indicated dependency of the mortality rates on the independent variables “stand, stem and leaning damages.” On the other hand, the recovery rates of damaged trees were dependent on crown, stem and leaning damages. Therefore, two years after harvesting a higher mortality rate of low-dimensional trees was observed in stands with high density of smaller trees and high density of improvement felling. Although crown damages were not related to mortality rates, high intensity of crown damages reduced recovery rates over time.

Evaluating changes in catchment‐scale evapotranspiration after 50% strip‐thinning in a headwater catchment

AbstractWe examined changes in catchment‐scale annual and seasonal evapotranspiration after 50% strip thinning, using runoff data from headwater catchments. The short‐term water balance (STWB) method between periods from 8 to 100 days was applied to the treated (KT) and control (KC) catchments. The estimated evapotranspiration during the pre‐ and post‐thinning periods were 840 and 910 and 780 and 860 mm/year in the catchments KT and KC, respectively. According to a paired catchment analysis of estimated evapotranspiration, monthly evapotranspiration increased from 3 to 20 mm from June to December, while it decreased from 7 to 31 mm from January to May. The estimated annual and monthly evapotranspiration was compatible with the values monitored in the plot‐scale interception, canopy transpiration, and ground surface evapotranspiration. Our findings showed that the decreases in evapotranspiration due to 50% thinning were similar or different in different methods of measurement when compared with thinning in the other catchments around the world. The STWB model can evaluate the effects of timber harvesting on changes in evapotranspiration (ET), including the reproduction of seasonal patterns of ET.

Improving the Contribution of Forests to Carbon Neutrality under Different Policies—A Case Study from the Hamburg Metropolitan Area

As various political initiatives have set goals to reach net-zero emissions by the mid-21st century, forests will play an important role as a carbon sink for sequestering unavoidable emissions. Forest management can take two approaches by either decreasing harvest and enlarging the forest carbon stock or increasing harvest to increase carbon uptake and create harvested wood products (HWPs). Currently, these two management options seem at odds with seemingly conflicting policy directives being written. We used the BEKLIFUH model to assess six management scenarios based on carbon offset potential taking into consideration forest carbon, HWPs and the material and energetic substitution effects. The results show that while conservation leads to a higher above-ground carbon pool, including HWPs, material and energetic substitution leads to more overall carbon offsets for management scenarios with more timber harvesting. With compromise being possible by selectively conserving old growth forests with a high biodiversity value. In conclusion, if the forest sector decouples GHG reporting from forest management and includes all the secondary effects of timber harvest, this new approach can lead to a different cost–benefit analysis for the choice between harvest vs. conservation. This could result in a paradigm shift to a future where biodiversity and carbon neutrality can coexist.

Local and sub-basin effects of timber harvests on stream macroinvertebrates in Hinkle Creek watershed

We studied the impacts of clear cut timber harvest over six-years, focusing on aquatic macroinvertebrate response using a BACI design. Data were collected before and after logging throughout a stream network to examine both local and downstream effects of upstream treatments. Sites were located in fishless headwater tributaries, fish-bearing tributaries and main stems in Hinkle Creek’s north fork (reference) and south fork (sequentially harvested) where benthic macroinvertebrates (from 2004 to 2009) and emergent insects (in 2005–2007 and 2009) were sampled. Pre-harvest (2004–2005) benthic macroinvertebrate composition was similar across sub-basins, with distinct longitudinal differences from tributaries to the main stems. At clear cut sites in fishless tributaries, benthic macroinvertebrate densities and percent Chironomidae increased, while taxa richness decreased, and these effects remained consistent for four years after the first harvest; aquatic insect emergence rates were also significantly higher in harvested v. reference fishless tributaries. No downstream macroinvertebrate responses were detected after the first harvest event. Following main stem harvest, confounded by a dam-break flood in December 2008, responses at main stem harvested sites were consistent with the localized responses observed in fishless tributaries, except benthic densities did not increase. While strong differences persisted among macroinvertebrates along the longitudinal gradient in the reference sub-basin, localized decreases in taxa richness and increased proportional contributions of generally disturbance tolerant chironomid midges among harvested sites resulted in altering the structure of invertebrate communities along the stream continuum. We conclude that additive effects of localized changes to instream resources along the stream continuum following successive harvest activities should be considered in plans for basin-wide timber harvests.

Fire Regime Has a Greater Impact Than Selective Timber Harvesting on Vegetation in a Sub-Tropical Australian Eucalypt Forest

We compared selectively harvested and unharvested areas located among treatments of annual burning since 1952, triennial burning since 1973 and an area that had received no prescribed burning, but with a single wildfire in 2006 (one fire in 72 years), in a dry sclerophyll eucalypt forest, south-eastern Queensland, Australia. Historic fire regime, rather than low-intensity, selective timber harvesting (17% to 37% live tree basal area removed) had a greater impact on a range of vegetation and soil attributes. Plant taxa composition was influenced more by historic fire regime than recent harvesting; of the 25.5% of the variation in taxa composition explained, fire treatments alone accounted for 96.4% of the explained variation and harvesting alone accounted for just 4.8%. Selective harvesting of timber had a predictable influence associated with removal of tree cover and physical impacts associated with extraction of logs. In harvested areas there were increases (p &lt; 0.05) in bare-ground cover and in coarse woody debris volumes and decreases in understorey vegetation height, particularly where woody understorey was present. However, overall, the combined effects of timber harvesting and fire regime were relatively minor. These sub-tropical dry eucalypt forests appear to be resilient to the impacts of combined, but low-intensity disturbances.

Towards sustainable forestry: Using a spatial Bayesian belief network to quantify trade-offs among forest-related ecosystem services

Assessing trade-offs among ecosystem services (ESs) that are provided by forests is necessary to support decision-making and to minimize negative effects of timber harvesting. In this study, we examined how spatial data, forest operational rules, ESs, and probabilistic statistics can be combined into a practical tool for trade-off analysis that could guide decision-making towards sustainable forestry. Our main goal was to analyze trade-offs among the wood provisioning ES and other forest ESs at the landscape level using a Bayesian belief network (BBN). We used LiDAR data to derive four ES layers as inputs to a spatial BBN: (i) wood provisioning; (ii) erosion regulating; (iii) climate regulating; and (iv) habitat supporting. We quantified operational constraints with four forest operational rules (FOR) that were defined in terms of: (i) potential harvest block size; (ii) distance between a small potential harvest block and a larger harvest block; (iii) gross merchantable volume (GMV); and (iv) distance to an existing resource road. Maps of the most probable trade-off classes between the wood provisioning ES and other ESs enabled us to identify areas where timber harvesting should be avoided or where timber harvesting should have a very low negative effect on other ESs. Even with our most restrictive management scenario, the total GMV that could be harvested met the annual allowable cut (AAC) volume required to meet sustainable forestry objectives. Through our study, we demonstrated that high-resolution spatial data could be used to quantify trade-offs among wood provisioning ES and other forest-related ESs and to simulate small changes in ES indicators within the BBN. We also demonstrated the potential to evaluate management scenarios to reduce trade-offs by considering FOR as inputs to the BBN. Maps of the most probable trade-off classes among two or three ESs under operational constraints provide key information to guide forest management decision-making towards sustainable forestry.

Soil nutrient recovery after shelterwood timber harvesting in a temperate oak hardwood forest: Insights using a twenty-five-year chronosequence

Understanding the effects of forest timber harvests on soil chemistry is essential to manage for a sustainable yield of timber from forests. Yet few studies have examined the long-term effects of timber harvesting on the soils of temperate hardwood forests. We use a 25-year chronosequence of post-regeneration irregular shelterwood harvests in an oak-hardwood forest in Connecticut, USA to examine the impacts of timber harvesting and subsequent forest regeneration on soil and leaf litter chemistry. Soil and leaf litter samples were collected across 34 stands ranging in age from one year to 25 years since harvest. Using hierarchical, linear mixed effects models, we analyzed trends in soil and leaf litter properties over time in the harvested stands and compared these values to undisturbed reference sites. Soil chemistry from two depths (0–10 and 10–20 cm) revealed that surface and sub-surface soils respond differently through time, with the shallow soils being more responsive to harvest and regeneration, but both increasing in fertility with increasing time since harvest. In shelterwood soils, time since harvest had a positive effect on macronutrient concentrations and a negative effect on the carbon (C) stable isotope ratio (δ13C), with the latter indicative of recovery of faster-cycling soil C pools. In leaf litter, time since harvest had a positive effect on nitrogen (N) concentrations and a negative effect on δ13C, with the latter again suggesting build-up of more recent litter inputs. Relative to eight unmanaged reference sites, harvested stands were lower in some soil nutrients (magnesium, phosphorus, percent C, as well as cation exchange capacity), but these differences were recovered over time within the 25-year chronosequence. Post-hoc t-tests (α = 0.10) showed no significant difference in percent nitrogen by 11–15 years post-timber harvest as compared to the undisturbed sites. Likewise, potassium, phosphorus and percent carbon showed no difference by 16–20 years, and magnesium showed no difference by 21–25 years. Calcium never varied significantly between shelterwood and uncut reference sites. Overall, our results suggest that decomposing organic matter acts quickly to promote macronutrient recovery in surface soils following irregular shelterwood harvests.

Effects of timber harvest on epigeous fungal fruiting patterns and community structure in a northern hardwood ecosystem

Epigeous fungal fruiting has important impacts on fungal reproduction and ecosystem function. Forest disturbances, such as timber harvest, impact moisture, host availability, and substrate availability, which in turn may drive changes in fungal fruiting patterns and community structure. We surveyed mushrooms in 0.4 ha patch cuts (18 months post-harvest) and adjacent intact hardwood forest in northern New Hampshire, USA, to document the effects of timber harvest on summer fruiting richness, biomass, diversity, and community structure of ectomycorrhizal, parasitic, and saprobic mushroom taxa. Fungal fruiting richness, diversity, and community heterogeneity were greater in intact forests than patch cuts. Among functional groups, ectomycorrhizal fruiting richness, diversity, and biomass were greater in unharvested areas than in the patch cuts, but parasitic and saprobic fruiting did not differ statistically between the two forest conditions. Our findings suggest that timber harvest simplifies fungal fruiting communities shortly after harvest, in particular triggering declines in ectomycorrhizal taxa which are important symbionts facilitating tree establishment and regeneration. Multi-aged silvicultural practices that maintain mature forest conditions adjacent to and throughout harvested areas through deliberate retention of overstory trees and downed woody material may promote fungal fruiting diversity in regenerating stands.

Effects of timber harvest on survival and movement of stream salamanders in a managed forest landscape

AbstractWith escalating anthropogenic alteration of landscapes worldwide, managed forests are increasingly important as providers of ecosystem services and wildlife habitat. Therefore, it is crucial to maintain a balance between producing forest products and biodiversity conservation. Several studies have reported negative effects of forest management on terrestrial plethodontid salamanders, but fewer have focused on stream‐dwelling species or evaluated mechanisms for shifts in their abundance (e.g., mortality vs. movement). We used a before–after–control–impact design to examine the effects of clear‐cut harvesting on a semi‐aquatic stream‐breeding salamander endemic to the Ouachita Mountains, Desmognathus brimleyorum. We conducted a three‐year capture–mark–recapture (CMR) study at three streams within a managed pine (Pinus spp.) landscape in west‐central Arkansas, USA. Loblolly pine (Pinus taeda) stands surrounding two of the streams were clear‐cut (leaving a 14–21 m wide forested buffer on each side of the stream) midway through the study; the third stream served as a control site and remained unharvested. We estimated apparent survival using open CMR models and compared salamander movement over time and between harvested and control streams. Overall, our models revealed seasonal and temporal variation in salamander survival and abundance, but little evidence for strong immediate effects of timber harvesting on post‐metamorphic salamanders within two years postharvest. However, there was increased salamander movement at sites where forest harvest occurred. Our results suggest that streamside buffers of at least 14–28 m on either side of a stream are effective for minimizing immediate effects of forestry activities on juvenile and adult stream‐dwelling salamanders, when timber harvest occurs in the winter months. These results will inform management decisions aimed at conserving biodiversity and ecosystem integrity in managed forest landscapes while also filling a critical gap in the knowledge of stream salamander demographic parameters.

Macromoth community structure along a 95‐year post‐harvest chronosequence in managed forests of northwest Washington State (U.S.A.), with comparison to old growth forest communities

The effects of timber harvest in the moist coniferous forests of western North America are not well documented for ecologically important arthropods such as moths. We assessed the response of macromoth community structure (abundance, sample size‐corrected estimates of species richness and diversity, and overall community composition) to time since deforestation at 20 previously logged sites (1–95 years post‐harvest), and compared the macromoth communities at these stands to four old growth stands. As stand age increased following timber harvest, the number of macromoths captured in ultraviolet light traps increased and the relative abundance of dietary generalists declined, but sample size‐corrected estimates of species richness and diversity did not vary. Macromoth community composition of the youngest stands (&lt;10 years post‐harvest) differed markedly from each other but converged soon thereafter. Macromoth communities at old growth sites featured higher capture rates, lower dominance by dietary generalists, and higher sample size‐corrected estimates of species richness and diversity than at previously logged sites. Community composition profiles for old growth sites differed from all previously logged sites, but the differences were subtle except in comparison to the youngest logged sites. None of the 188 species we sampled were old growth specialists. Our results reveal dramatic initial impacts of deforestation on macromoth communities in moist coniferous forests of western North America. Such effects are largely reversed within two decades post‐harvest but some effects persist for at least 95‐years following logging.

Evaluating the effects of timber harvest on hydrologically sensitive areas and hydrologic response

Effects of forest treatments on watershed hydrology in terms of water yield and runoff processes is a primary concern. This paper evaluates the effects of long-term land cover change on hydrological processes in the Mica Creek Experimental Watershed (MCEW) in northern Idaho, USA. In the MCEW, effects of clearcut and partial cut harvest practices on streamflow were monitored and evaluated from 1991 to 2013. Firstly, snowpack dynamics in terms of snowmelt timing and average melt rate under different elevations, aspects, land covers, and climate conditions were analyzed at the point-scale with the snow accumulation and melt (SAM) model from the perspective of the energy balance. Then, the grid-based soil moisture routing (SMR) hydrology model was used to provide temporal and spatial hydrological changes in the MCEW. We assigned locations as hydrologically sensitive areas (HSAs) based on the probability of runoff generation (P(Ai = HS)) to capture potential downstream environmental effects of actual land cover change and optimal harvest patterns. The results highlight the strong impacts timber harvest can have on increasing streamflow and, in particular, peak flow. On average, the daily averaged degree of saturation increased by 20% after timber harvest resulting in higher risks of flooding from large rainfall events. Three logging scenarios including logging in areas with low P(Ai = HS), high P(Ai = HS), and in the entire watershed area, showed that logging areas had a positive relationship with water yield and that more extreme peak flow was likely to occur after clearcutting in high P(Ai = HS) areas (high elevation) under rainfall driven events or logging in low P(Ai = HS) areas (medium elevation) during snowmelt dominated events. Clearcutting on south-facing slopes at medium elevation strongly increased the average melt rate leading to potential flooding if a snowpack was present and temperatures increased. Scenario analysis suggests that partial cutting in areas with low P(Ai = HS) would reduce peak flow amount by as much as 40%. However, for watersheds to be logged entirely, choosing proper harvest locations such as clearcutting in high P(Ai = HS) areas having large snow events may effectively reduce extreme peak flow from spring snowmelt. Our findings inform forest management decisions favoring partial cutting over clearcutting, and how to avoid concentrating harvest practices in HSAs by adapting spatial distribution and timing of harvesting to climate conditions to minimize impacts on the water cycle.

The past, present and future impacts of climate and land use change on snowshoe hares along their southern range boundary

Changes in land use and climate are among the main drivers of range shifts for multiple species and taxa. While such distributional changes are often observed at broad scales, the processes driving them – colonization and extinction along range boundaries – occur at local scales. There is a need then, to identify whether these local drivers are consistent with patterns at broader scales. Snowshoe hares (Lepus americanus), an important prey species in northern forest ecosystems, have experienced range contraction along much of their southern boundary. Population declines are linked to climate change via camouflage mismatch, an inability to match seasonal coat color molts with declining snow cover duration. We used data from camera traps to monitor the spatial extent and habitat associations of hares before, during and after an experimental translocation, and multi-season occupancy models to model the effects of habitat and climate on colonization and extinction patterns. We compared our contemporary occupancy models to historical patterns of extirpation and simulated future effects of timber harvest on occupancy. Colonization by hares was strongly associated with distance from source population and patch size of aspen-alder. Historical patterns of extirpation were consistent with contemporary patterns, and simulations revealed that increased frequency and magnitude of aspen harvest increased hare occupancy by creating large patches of early-successional habitat. As global change alters ecological communities, identifying mechanisms that drive range-shifts and targeting landscape features that can be manipulated to buffer those effects can be used to promote the persistence of individual species and ecological communities.

Forest riparian buffers reduce timber harvesting effects on stream temperature, but additional climate adaptation strategies are likely needed under future conditions.

Stream water temperature imposes metabolic constraints on the health of cold-water fish like salmonids. Timber harvesting can reduce stream shading leading to higher water temperatures, while also altering stream hydrology. In the Pacific Northwest, riparian buffer requirements are designed to mitigate these impacts; however, anticipated future changes in air temperature and precipitation could reduce the efficacy of these practices in protecting aquatic ecosystems. Using a combined modeling approach (Soil and Water Assessment Tool (SWAT), Shade, and QUAL2K), this study examines the effectiveness of riparian buffers in reducing impacts of timber harvest on stream water temperature in Lookout Creek, Oregon across a range of potential future climates. Simulations assess changes in riparian management alone, climate alone, and combined effects. Results suggest that maximum stream water temperatures during thermal stress events are projected to increase by 3.3-7.4 °C due to hydroclimatic change alone by the end of this century. Riparian management is effective in reducing stream temperature increases from timber harvesting alone but cannot fully counteract the additional effects of a warming climate. Overall, our findings suggest that the protection of sensitive aquatic species will likely require additional adaptation strategies, such as the protection or provisioning of cool water refugia, to enhance survival during maximum thermal stress events.

Timber harvest and frequent prescribed burning interact to affect the demography of Eucalypt species

Ecosystem management can negatively affect the demography of plant communities through the introduction of novel disturbance regimes. Prescribed burning and timber harvesting are two common and widely applied management strategies across forest ecosystems. Despite this, little is known about the long-term effects that these interacting disturbances have on forest demography. This study examined the effect of timber harvesting and frequent prescribed burning on the mortality, growth and regeneration of trees in a temperate eucalypt forest of south-eastern Australia. The study took place at a long-term experimental site, where experimental coupes were subjected to a one-off selective harvesting treatment (harvested, not harvested), followed by regimes of experimental burning (no fire, ~4 year burn intervals or ~2 year burn intervals) over a 22 year period. Tree communities were surveyed at permanent monitoring sites prior to the application of experimental treatments (1985 – 1989), and resurveyed post treatment (2016) to assess mortality, growth rates and ingrowth of trees >10 cm diameter at breast height. Harvesting directly removed ~40% of trees and indirectly increased the mortality of retained trees through damage (e.g. crown and bole breakage) caused during the harvesting operation. The likelihood of harvesting damage was greater for small trees and increased with harvesting intensity (i.e. the amount of timber removed). Frequent burning increased the likelihood of tree mortality on harvested sites, with large, old trees being particularly vulnerable. Growth rate and ingrowth of trees was elevated at harvested sites, increasing almost linearly with harvesting intensity, which suggests that competitive release had occurred. Fire frequency had no effect on growth rates or ingrowth of trees. This study highlights that frequent prescribed burning and selective timber harvesting can have additive effects on the loss of large trees, reducing the availability of these keystone habitat structures in intensively managed forest ecosystems. Although the elevated rates of growth and ingrowth may hasten the replacement of lost large trees, recovery will require long time frames.

Environmental And Socio-Economic Effects Of Timber Exploitation In Imo River Estuary, Eastern Obolo, Akwa Ibom State, Nigeria

Purpose: This study was carried out to evaluate the environmental and socio-economic effects of timber harvesting as well as to identify the drivers increasing the rate of timber exploitation in Imo River Estuary, Eastern Obolo Local Government Area, Akwa Ibom state, Nigeria.&#x0D; Methodology: It was conducted in five Local Government Areas (LGAs) in Eastern Obolo Local Government Area, Akwa Ibom state, Nigeria. A random sampling technique was employed to select a total of 300 respondents composed of 60 randomly selected respondents from each of the five LGAs. A structured questionnaire was used in collecting information from the respondents. Data acquired from the field was subjected to statistical and econometric analysis which included percentages, frequencies, Likert scale rating, exploratory factor analysis, and Chi-square,&#x0D; Main Findings: The major finding of this study was that the major cause of timber exploitation in the study area was unemployment, absence of forest regulations, unstable government policies, lack of trained officials, and high cost of timber products. The application of the Factor Analysis Model in this study showed that loss of biodiversity, the disappearance of forest cover, damaging of immature trees and non-wood forest products are the highest environmental effects of timber exploitation in the study area, loading far higher than the stated 0.3 decision score value. Among the social effects, high cost of farm labor is the most severe of social effects in the study area, while the increased cost of wood and forest product and high cost of living ranked highest among the economic effects.&#x0D; Applications: The study will be of great importance to environmental policy makers, conservationists, researchers, and Geographers in Nigeria. It will contribute significantly to knowledge build-up in relation to restoring the sanctity of threatened forests in Southern Nigeria.&#x0D; Novelty/Originality: The Niger Delta region of Nigeria where this study was carried out is often synonymous with militancy and the problems of environmental pollution. However, this study veers from these already known challenges to peculiar drivers of the depleting forests in this area. The study, therefore, will contribute to the scanty literature related to the subject matter within the study area.