Search

The impact of waterfowl harvest on the dynamics of duck populations remains incompletely understood. While widescale monitoring and management programs have been set up in North America, far less has been done in Europe where populations and harvest are essentially managed at country level with a sole focus on population size. Hence, comparing North American waterfowl populations with European waterfowl populations could be useful in suggesting flywayscale management options in Europe. In our paper, we analyse historical capture-recapture-recoveries data for the European teal Anas crecca crecca and we compare the computed survival and harvest rates to those obtained from a North American recovery data set for the green-winged teal Anas crecca carolinensis, its sister taxon. During 1960-1976, the annual probability of survival was slightly lower in Europe (average over sexes: 0.485 6 0.101) than in North America (0.54560.010 for both sexes). Assuming a30%ring reporting rate, our estimate of the annual harvest rate was about three times higher in Europe (average over sexes: 0.17860.051) than in North America (average over sexes: 0.071 6 0.014). Although the European population increased over the study period and continues to do so, such a hunting pressure may potentially reduce our flexibility in managing this population due to uncertainties such as environmental changes, and have deleterious effects in the long term.Weuse our results to discuss waterfowl research and management in Europe. Initiating studies to estimate ring reporting rate would be an essential first step to properly evaluate the impact of harvest on the dynamics of the teal population in Europe. [ABSTRACT FROM AUTHOR]

1. This paper reviews and compares the effects of forest fire and timber harvest on mammalian abundance and diversity, throughout successional time in the boreal forest of North America.2. Temporal trends in mammal abundance and diversity are generally similar for both harvested and burned stands, with some differences occurring in the initiation stage (0–10 years post disturbance).3. Small mammals and ungulates are most abundant immediately post disturbance, and decrease as stands age. Lynxes and hares utilize mid-successional stands, but are rare in young and old stands. Bats, arboreal sciurids and mustelids increase in abundance with stand age, and are most abundant in old growth.4. Substantial gaps in the data exist for carnivores; the response of these species to fire and harvest requires research, as predator–prey interactions can affect mammal community structure in both early and late successional stages.5. The lack of explicit treatment of in-stand forest structure post disturbance, in the reviewed literature made comparisons difficult. Where forest structure was considered, the presence of downed woody material, live residual trees and standing dead wood were shown to facilitate convergence of mammal communities to a pre-disturbance state for both disturbance types.6. Mammalian assemblages differed considerably between successional stages, emphasizing the importance of maintaining stands of each successional stage on the landscape when implementing forest management strategies. [ABSTRACT FROM AUTHOR]

The genetic composition of mallards in eastern North America has been changed by release of domestically-raised, game-farm mallards to supplement wild populations for hunting. We sampled 296 hatch-year mallards harvested in northwestern Ohio, October–December 2019. The aim was to determine their genetic ancestry and geographic origin to understand the geographic extent of game-farm mallard introgression into wild populations in more westward regions of North America. We used molecular analysis to detect that 35% of samples were pure wild mallard, 12% were early generation hybrids between wild and game-farm mallards (i.e., F1–F3), and the remaining 53% of samples were assigned as part of a hybrid swarm. Percentage of individuals in our study with some form of hybridization with game-farm mallard (65%) was greater than previously detected farther south in the mid-continent (~4%), but less than the Atlantic coast of North America (~ 92%). Stable isotope analysis using δ2Hf suggested that pure wild mallards originated from areas farther north and west than hybrid mallards. More specifically, 17% of all Ohio samples had δ2Hf consistent with more western origins in the prairies, parkland, or boreal regions of the mid-continent of North America, with 55%, 35%, and 10% of these being genetically wild, hybrid swarm, and F3, respectively. We conclude that continued game-farm introgression into wild mallards is not isolated to the eastern population of mallards in North America, and may be increasing and more widespread than previously detected. Mallards in our study had greater incidence of game-farm hybridization than other locales in the mid-continent but less than eastern North American regions suggesting further need to understand game-farm mallard genetic variation and movement across the continent. [ABSTRACT FROM AUTHOR]

Post‐harvest recovery of biodiversity is one of important goals in modern forestry. A variable retention (VR) approach has been of particular interest in North America because it promotes rapid faunal recovery, while minimizing negative lasting impacts of logging on the natural fauna. We studied responses of rove beetles (Coleoptera: Staphylinidae) to a broad range of retention harvests (2, 10, 20, 50 and 75% retention) in comparison to uncut controls as part of the Ecosystem Management Emulating Natural Disturbance (EMEND) experiment in the boreal mixedwood forest of western Canada. We sampled beetles using pitfall traps 1, 2, 11 and 16 years post‐harvest in replicated (n = 3) stands representing four cover types (deciduous‐dominated, deciduous with spruce understory, mixed and coniferous‐dominated). We collected 74 263 individuals distributed across 99 species (excluding Aleocharinae). Estimated species richness was highest in clear‐cuts until year 11, but by year 16 species richness was similar among treatments. Species composition initially varied strongly in relation to intensity of harvest treatments, but overall variation decreased with time, and by year 16, species composition overlapped among most treatment combinations. Assemblages recovered more quickly in early successional (deciduous‐dominated) than in late successional (mixed and conifer‐dominated) stands. Overall, our results show that rove beetle assemblages in stands harvested to all VR prescriptions converged more rapidly toward those in fire‐origin mature stands than did assemblages in clear‐cuts over the first 16 years post‐harvest. Thus, it demonstrates that even modest levels of forest retention can facilitate the recovery of staphylinid assemblages in managed landscapes. [ABSTRACT FROM AUTHOR]

Copyright of Ager: Journal of Depopulation & Rural Development Studies / Revista de Estudios sobre Despoblación y Desarrollo Rural is the property of Rolde de Estudios Aragoneses and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Sustainable conservation and management of valued resources and ecosystem services relies on understanding the dynamics of the socio-ecological system. In the case of wild rice, a cherished food resource of Northern Great Lakes landscapes, the dynamics involve (a) a changing distribution of wild rice lakes, (b) changing harvester population and demographics, and (c) different management overlays. Together these factors influence harvester choices and opportunities and create unexpected spatial dynamics between people and the lakes they harvest. In this paper we examine first, the regional distribution and characteristics of wild rice lakes through compilation of multi-agency data, geospatial analysis, license sales and harvest surveys. Second, we identify patterns of harvest in the region through six case study lakes and examine the decision-making models used to open lakes for harvest. Gathered together these various forms of knowledge and collected data sets inform our understanding of the social–ecological systems involving wild rice (Zizania palustris). Watersheds with wild rice have declined by 32% since the early 1900s, and are now primarily limited to northern Minnesota and Wisconsin. Across case studies wild rice harvesters tend to gather wild rice close to where they live or learned to harvest and 50% have more than 20 years experience. Some wild rice lakes draw harvesters from greater distances and in higher numbers. Models for managing the harvest of wild rice range from ‘gather when ripe’ by state entities to a more hands-on posting by reservation committees specifying hours and days of harvest on a lake by lake basis. The social–ecological system around wild rice is a complex mosaic of multiple management jurisdictions, culturally diverse people, and an ecological system that is not well understood and potentially declining in extent. Defining the context of harvest within the spatially connected landscape and across multiple management systems is a first step in developing a shared framework of governance for the sustainability of wild rice landscapes. [Copyright &y& Elsevier]

Skidding is an important element of harvesting operations, which contributes to the extraction of wood. A skidder can be used in different types of harvesting operations, such as thinning, clear fell, native forest thinning or salvage work. The main goal of this article was to review the available studies on productivity of skidding operations in coniferous forests/ plantations. Information on skidder productivity was collected from publications and then was classified in three regions, including North America, Europe and the Southern Hemisphere. The parameters affecting machine productivity included machine type/ size, tree volume/ log volume/ load volume, average skidding distance and slope of the ground for each reported productivity. The average productivity reported in the published reports ranged from 9.3 m3/PMH to 78.0 m3/PMH. Detailed information and conclusions collected from various studies can be of use to forest academic and industry users to gain knowledge about variations of skidder productivity in different regions and site/ operation conditions, which can be helpful for predicting, controlling and improving current levels of productivity. [ABSTRACT FROM AUTHOR]

The influence of human harvest on evolution of secondary sexual characteristics has implications for sustainable management of wildlife populations. The phenotypic consequences of selectively removing males with large horns or antlers from ungulate populations have been a topic of heightened concern in recent years. Harvest can affect size of horn‐like structures in two ways: (a) shifting age structure toward younger age classes, which can reduce the mean size of horn‐like structures, or (b) selecting against genes that produce large, fast‐growing males. We evaluated effects of age, climatic and forage conditions, and metrics of harvest on horn size and growth of mountain sheep (Ovis canadensis ssp.) in 72 hunt areas across North America from 1981 to 2016. In 50% of hunt areas, changes in mean horn size during the study period were related to changes in age structure of harvested sheep. Environmental conditions explained directional changes in horn growth in 28% of hunt areas, 7% of which did not exhibit change before accounting for effects of the environment. After accounting for age and environment, horn size of mountain sheep was stable or increasing in the majority (~78%) of hunt areas. Age‐specific horn size declined in 44% of hunt areas where harvest was regulated solely by morphological criteria, which supports the notion that harvest practices that are simultaneously selective and intensive might lead to changes in horn growth. Nevertheless, phenotypic consequences are not a foregone conclusion in the face of selective harvest; over half of the hunt areas with highly selective and intensive harvest did not exhibit age‐specific declines in horn size. Our results demonstrate that while harvest regimes are an important consideration, horn growth of harvested male mountain sheep has remained largely stable, indicating that changes in horn growth patterns are an unlikely consequence of harvest across most of North America. [ABSTRACT FROM AUTHOR]

In temperate and boreal mixedwood forests of eastern North America, partial disturbances such as insect outbreaks and gap dynamics result in the development of irregular forest structures. From a forest ecosystem management perspective, management of these forests should therefore include silvicultural regimes that incorporate medium- to high-retention harvesting. We present 12-year results of a field experiment undertaken to evaluate the effects of variable retention harvesting on stand structure, recruitment, and mortality. Treatments were gap harvesting (GAP), diameter-limit harvesting (DL), careful logging (CL), and careful logging followed by scarification (CL + SCAR), and an unharvested control. Although post-harvest basal area in the GAP treatment was significantly lower than that of controls, it maintained a diameter distribution profile and densities of balsam fir regeneration similar to those of pre-harvest conditions. Lower retention treatments (DL, CL, and CL + SCAR) tended to favor regeneration of pioneer, shade-intolerant species. Except for black spruce (for which mortality was highest in DL), stem mortality was similar among harvesting treatments. From an ecosystem management perspective, this study suggests that gap harvesting can maintain, in the short term, forest stand composition and structure similar to unharvested forests, and could be used where management objectives include the maintenance of late successional forest conditions. [ABSTRACT FROM AUTHOR]

Alfalfa was integral to the agricultural revolution in Europe because of the plant's soil nitrifying properties and was widely introduced throughout North America. American folkways eventually addressed planting, harvesting, plant protection, and uses of alfalfa as animal forage and human medicine. Tall tales and folk heroes featured the plant, and it was viewed as bringing luck and success. Alfalfa festivals, including Alfalfa Queens and Princesses (both human and livestock), became widespread in the West and Midwest. 'Alfalfa' was used to name fictitious as well as historical persons and places. Alfalfa, the world's most important forage legume, is scarcely represented in standard folkloristic references, a deficiency corrected by this compilation of North American folkways. [ABSTRACT FROM AUTHOR]

Balsam fir (Abies balsamea[L.] Mill.), which is widely used for floral greenery, is an important source of nontimber forest products (NTFP) from the northern forests of North America. Nonetheless, additional information is needed to refine and revise commercial tip-harvesting management guidelines to promote sustainable forest management. Therefore, a study was initiated to: (a) examine the socioeconomic impacts of and anticipate the potential biological responses to four contrasting harvesting practices; (b) discuss the implications of the results for the relevance and applicability of some specifications of management guidelines; and (c) assess the compatibility of tip harvesting while pursuing an objective of timber production. [ABSTRACT FROM PUBLISHER]

Human harvesting is often a major mortality factor and, hence, an important proximate factor driving the population dynamics of large mammals. Several selective harvesting regimes focus on removing animals with low reproductive value, such as 'antlered' harvests in North America and juvenile harvesting in many European countries. Despite its widespread use and assumed impact, the scientific basis of juvenile harvesting is scattered in the literature and not empirically well-documented. We give the first overview of demographic, evolutionary and practical management arguments for selective harvesting of juveniles. Furthermore, we empirically test two demographic arguments based on harvest statistics of Red Deer ( Cervus elaphus) in seven European countries. P: Harvesting juveniles has little influence on harvest growth compared with harvesting adult females due to the lower reproductive value of juveniles than adult females; P: Harvesting of juveniles dampens variance in harvest due to lower and more variable natural survival rates of juveniles compared with adults. We found that harvesting juveniles has little effect on harvest growth rate, while harvesting adult females has a significant negative effect (consistent with P), but that increasing the proportion of juveniles in the harvest did not decrease the variability in harvest between years (P not supported). Based on our empirical findings and overview of arguments, we discuss how the merits of juvenile harvesting may vary over time as populations move from a low density to a very high density state. [ABSTRACT FROM AUTHOR]

Boreal forest carbon (C) storage and sequestration is a critical element for global C management and is largely disturbance driven. The disturbance regime can be natural or anthropogenic with varying intensity and frequency that differ temporally and spatially the boreal forest. The objective of this review was to synthesize the literature on C dynamics of North American boreal forests after most common disturbances, stand replacing wildfire and clearcut logging. Forest ecosystem C is stored in four major pools: live biomass, dead biomass, organic soil horizons, and mineral soil. Carbon cycling among these pools is inter-related and largely determined by disturbance type and time since disturbance. Following a stand replacing disturbance, (1) live biomass increases rapidly leading to the maximal biomass stage, then stabilizes or slightly declines at old-growth or gap dynamics stage at which late-successional tree species dominate the stand; (2) dead woody material carbon generally follows a U-shaped pattern during succession; (3) forest floor carbon increases throughout stand development; and (4) mineral soil carbon appears to be more or less stable throughout stand development. Wildfire and harvesting differ in many ways, fire being more of a chemical and harvesting a mechanical disturbance. Fire consumes forest floor and small live vegetation and foliage, whereas logging removes large stems. Overall, the effects of the two disturbances on C dynamics in boreal forest are poorly understood. There is also a scarcity of literature dealing with C dynamics of plant coarse and fine roots, understory vegetation, small-sized and buried dead material, forest floor, and mineral soil. [ABSTRACT FROM AUTHOR]

There are nine acipenseriform species in North America: two on the Pacific Coast, two on the Atlantic Coast, and five purely freshwater forms. Six of these species are subject to commercial harvest and three to aquaculture. The North American sturgeon and paddlefish meat and caviar marketplace is comprised of legally and illegally acquired products from wild and captive populations of indigenous species as well as non-indigenous species from import and/or culture. Overall, at least 11 species can legally occur in the market. Future aquaculture development will most certainly increase this number. Some indigenous species subject to commercial harvest or culture are under partial or complete range protection, adding another layer of monitoring complexity at the population specific level. We identify four primary levels of confusion in the identification of caviar from North American acipenseriforms in North America: among North American species, among populations within a North American species, between wild and farmed specimens of a North American species, and between North American and imported non-North American species. This complexity reveals the need for additional research into forensic tools, species boundaries and population structure if effective enforcement of harvest and market restrictions is to ensue. For species not subject to commercial harvest and trade, research is needed to identify illegal products from the species. [ABSTRACT FROM AUTHOR]

Copyright of Conservation Biology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

An open access model is formulated where X is a renewable resource and E is the level of effort devoted to harvest. Net growth is assumed to exhibit critical depensation and the open access system is described by two nonlinear differential equations X = rX(X/K1 - 1)(1 - X/K2) - qXE and E = α[(p - s)qXE - cE], where r > 0 is the intrinsic growth rate, K1 is the minimum viable population level, K2 is the environmental carrying capacity, K2 > K1 > 0, q > 0 is the catchability coefficient, α > 0 is an adjustment coefficient, (p - s) > 0 is the market price net of shipping cost, and c > 0 is the unit cost of effort at the harvest site. It is shown that the E = 0 isocline is a vertical line at X∞ = c/[(p - s)q] and that the open access system passes through a supercritical Hopf bifurcation as X∞ moves from a level above (K1 + K2)/2 to a level below (K1 + K2)/2. For X∞ above (K1 + K2)/2 the open access equilibrium is locally stable. For X∞ below (K1 + K2)/2 the open access equilibrium will be locally unstable. At X∞ = (K1 + K2)/2 the system has a stable limit cycle. This analysis is useful in interpreting the economic history of the passenger pigeon. The limited empirical evidence would suggest that X∞ = c/[(p - s)q] declined below (K1 + K2)/2 during the last half of the 19th century as a result of improved rail transport and communications (the telegraph). It is thought that the passenger pigeon was extinct in the wild by 1901. The last passenger pigeon died in captivity at the Cincinnati Zoological Gardens on September 1, 1914. [ABSTRACT FROM AUTHOR]