Harvest Intensity Research Articles

Metabarcoding of American Mink Scat to Explore Shifting Baselines in the Gulf of Maine

The mink (Neogale sp.) has been important species in North American ecosystems and communities for millennia; before European colonization, Indigenous families hunted and trapped mink for their pelts. As part of the euro-colonial fur trade (~1600-1900), wide-spread and intense harvest of mink and other furbearers transformed ecosystems, including the likely extinction of the sea mink (Neogale macrodon) in the Gulf of Maine. The American mink (Neogale vison) has slowly moved into areas that were previously inhabited by the sea mink in coastal and island Maine. The expansion of American mink has been implicated as a potential cause for the declining seabird populations on Maine islands. Here, we use metabarcoding of American mink scat collected in the USFWS Maine Coastal Islands National Wildlife Refuge to evaluate if American mink are predating upon seabirds. Preliminary analysis of mink scat from Petit Manan Island has not implicated mink in bird predation but we did recover host DNA and dietary components including lobster and fish (Cunner). Currently, managers remove American mink from the Refuge islands to protect nesting seabirds but perhaps the seabird populations are returning to population sizes of when sea mink was present in the area. Harvest of furbearers as part of the euro-colonial fur trade may still have implications for ecosystem form and function today.

Commercial and subsistence harvests of bowhead whales (Balaena mysticetus) in eastern Canada and West Greenland

Commercial harvesting of bowhead whales (Balaena mysticetus) from the eastern Canada-West Greenland population started with Basque whalers in the Strait of Belle Isle ca 1530 AD. Subsistence harvests have an even longer history, and the first culture to be active bowhead whalers was the Thule, which replaced the Dorset culture in the central and eastern Arctic ca 1200 AD. Previous harvest compilations have been incomplete, and back-calculated population models have thus been negatively biased. In recent decades this population has shown significant recovery and is the subject of Inuit subsistence harvests in both Canada and West Greenland. A revised historic abundance estimate is needed to examine the level of recovery; this requires inter alia a revised and updated catch series. Available information from multiple anthropological, archaeological, historic and recent sources, and estimate commercial and subsistence harvests in eastern Canada and West Greenland is summarised. From 1530–1915, commercial whalers took an estimated 55,916–67,537 (median 61,537) bowhead whales (varying assumptions on the intensity of the Basque harvest), which is known to be incomplete. Inuit harvests before commercial whaling began (1200–1529 AD) were estimated at 11,435 whales, based on the abundance of whale bone at winter houses excavated by archaeologists. After 1500 AD, Inuit whaling declined, and the total estimated harvest between 1530 AD and the end of commercial whaling was 8,406 whales. Inuit whaling declined again after commercial whalers overharvested the population and only 65 whales are known to have been harvested (or struck and lost) from 1918–2009. The Inuit harvest statistics are based on scattered data and a number of assumptions, with some evidence that at least parts of the series are underestimated. Even if harvests were higher, they would have probably not been large enough to cause population declines. The long tradition of Inuit bowhead whaling was negatively impacted by commercial harvests. Combining all harvests from 1530–2009 AD results in a total estimated kill of some 70,000 whales (not including struck and lost whales and known gaps for some nations and eras), with most (88%) taken by commercial whalers. Data quality varies considerably by nation and era, and was assigned to a 3-point scale for reliability, with over half the harvest considered to be the least reliable. This is the most comprehensive summary and estimate of bowhead harvests for this region, but is still known to be incomplete and is based on a number of assumptions and disparate data sources.

Long-term effects of clearcut and selective cut on seepage chemistry in a N-saturated spruce stand – Case study Höglwald

While comprehensive literature is available concerning the effects of clearcutting on N leaching via seepage water little information is available comparing different harvesting intensities. In order to close this gap of knowledge in 1999 an experiment comparing selective cut and clearcut at the Höglwald site was started. The Höglwald is a major Central European ecosystem study site and represents a typical spruce forest ecosystem in Southern Germany, subject to high nitrogen deposition. Bulk deposition, throughfall and seepage water concentrations at 0 and 40 cm depth were measured from 1999 until 2017 at three plots (control, clearcut, selective cut). Elemental fluxes were calculated using measured water fluxes (precipitation, throughfall) or calculated soil water fluxes using a hydrological model. Here we present the final results for the 17-year measurement period comparing different harvesting intensities from initial harvesting until the complete removal of all mature trees.Initial nitrate peaks after clearcutting the nitrogen saturated spruce ecosystems were very high (up to 34 mg nitrate-N l−1) but short-lived (2 years). Afterwards nitrate leaching strongly decreased to values close to zero due to reduced input and the demand of the upcoming vegetation. For the investigated 17-year period cumulative nitrogen losses at the clearcut plot were lower as compared to the uncut control. The selective cut was not able to prevent nitrate leaching in our N-saturated spruce stand. Here cumulative nitrogen losses in the first 17 years are similar compared to the uncut control due to a combination of ongoing high deposition and partially enhanced mineralisation after harvesting events.At our nitrogen saturated study site the selective cut showed no advantages concerning nitrate leaching via seepage water. From a silvicultural and forest ecological point of view, however, big cleared areas with their sudden change to a non-forest climate should be avoided due to several disadvantages like high initial mineralisation with its excessive nutrient release, the risk of grass invasion as well as higher stress and often lower quality of the planted trees.

Producción de restos vegetales y descomposición de hojarasca foliar bajo distintas intensidades de corta en fajas en matorrales

Biomass extraction in native forests can induce changes in the functioning of these ecosystems; these changes are poorly studied, and this represents a knowledge gap. In this work, we evaluated the response of plant litter production and decomposition to increasing intensities of strip cutting in native scrublands. We set an experiment replicated in three sites: hillside with southern exposure (FS), hillside with northern exposure (FN) and valley bottom (R), with four intensities of strip cutting (0, 30, 50, and 70% of the area). To evaluate decomposition, we used bags filled with ñire leaves (Nothofagus antarctica), and for the production of litter, plastic mesh collectors. In addition, vegetation height and cover were measured. In the three sites, we observed the same temporal pattern of decomposition, with a marked decrease in organic matter during the coldest period of the year. The effects of cutting intensity were strongly influenced by the site: at FS, litter production increased, but there was no effect on decomposition; in contrast, at FN and R, production decreased and a curvilinear pattern was observed, with highest decomposition at intermediate harvest intensity. Aerial cover was positively correlated with production, and this, in turn, negatively correlated with decomposition. Our results suggest that in scrublands with high vegetation cover, strip cutting could promote litter production without affecting decomposition. In contrast, less productive sites with lower vegetation cover would be more sensitive to forestry interventions.

Variation Patterns of Forest Structure Diversity after Set-Aside in Rarău-Giumalău Mountains, Romania

The present study aims to analyze the set-aside effect on the current structure diversity of mountain temperate forests from the Natura 2000 site Rarău-Giumalău. In the past 80 years, the area of entirely protected forests successively increased to up to 77% of the site. The description of past structure diversity was based on the analysis of management plans drawn up for these ecosystems after 1940, while their current structure diversity was based on a tree census carried out in 2015. The forests’ structure diversity was described in relation to: tree dimensional heterogeneity; wood volumes homogeneity of the living trees throughout the site; variability of the standing and lying dead wood volume; number and basal area of large trees; natural regeneration. The results show that forest stands where no harvest has ever been registered record the highest level of tree size heterogeneity, while in previously managed forests, the current structure diversity was influenced by the harvesting intensity. The dimensional diversity of trees also depends on the structure, density and age of forest stands at the moment when they are set aside. We observed that the volume of dead wood on the ground greatly increases after abandonment of timber production and that there is a progressive decrease in the number and percentage of large trees in the first 40 years after the last timber harvest, accompanied by a significant decrease in living trees volume. Nevertheless, the number of large trees in stands where the last timber harvesting occurred more than six decades ago is 1.8 times higher than that of the corresponding number in stands where no harvesting was ever performed. The time elapsed since the last harvest generated important changes in the regeneration process, which seems to stabilize after three decades. The forest stands’ reaction after set-aside very much depends on their characteristics at the time of exclusion from timber production, especially their age and structure. After 80 years since set-aside, the ecosystem processes and descriptors begin to look very much like those in the forests unaffected by human actions, but the old-growth characteristics have not entirely recovered.

Dynamics and recovery of forest understory biodiversity over 17 years following varying levels of retention harvesting

Abstract Retention harvesting is advocated as an alternative to intensive timber harvesting, such as clear‐cutting, to better maintain or facilitate recovery of biodiversity and other ecological values in managed forests. However, it is not clear how long the benefits of retention harvests persist. We investigated responses of understory vascular plant cover, richness, diversity (inverse Simpson index) and composition to a gradient in dispersed retention (2% [clear‐ cut], 10%, 20%, 50% and 75% retention; unharvested reference [100% retention]) at 3, 6, 11, and 17 years after harvest, in four boreal mixedwood forest types (deciduous (broadleaf)‐dominated, deciduous‐dominated with conifer understory, mixed, and conifer‐dominated) in western Canada. Understory cover and richness tended to increase in the short‐term (3 years), peaked at 6–11 years with differences following the gradient of harvesting intensity, then plateaued or declined in the second decade (17 years), by which time there were minimal or no differences among harvesting levels, including the reference. Responses for diversity were minimal. In contrast, composition varied along the gradient of harvesting intensity and showed little recovery towards the unharvested condition over the 17‐year period. Generally, for plant community composition, clear‐cut and lower retention treatments (10%, 20%) were similar to one another but differed from the higher retention and unharvested reference treatments. Synthesis and applications: Retention harvests can moderate the negative impacts of harvesting and facilitate the recovery of biodiversity. Our results suggest that for the cover, richness and diversity of understory vascular plants, this moderating influence is weak and short‐lived. However, higher levels of retention can temper changes in understory composition relative to the unharvested forest, but full recovery is likely to be slow and will be complicated by post‐harvest regeneration dynamics.

Balancing disturbance risk and ecosystem service provisioning in Swiss mountain forests: an increasing challenge under climate change

Climate change severely affects mountain forests and their ecosystem services, e.g., by altering disturbance regimes. Increasing timber harvest (INC) via a close-to-nature forestry may offer a mitigation strategy to reduce disturbance predisposition. However, little is known about the efficiency of this strategy at the scale of forest enterprises and potential trade-offs with biodiversity and ecosystem services (BES). We applied a decision support system which accounts for disturbance predisposition and BES indicators to evaluate the effect of different harvest intensities and climate change scenarios on windthrow and bark beetle predisposition in a mountain forest enterprise in Switzerland. Simulations were carried out from 2010 to 2100 under historic climate and climate change scenarios (RCP4.5, RCP8.5). In terms of BES, biodiversity (structural and tree species diversity, deadwood amount) as well as timber production, recreation (visual attractiveness), carbon sequestration, and protection against gravitational hazards (rockfall, avalanche and landslides) were assessed. The INC strategy reduced disturbance predisposition to windthrow and bark beetles. However, the mitigation potential for bark beetle disturbance was relatively small (− 2.4%) compared to the opposite effect of climate change (+ 14% for RCP8.5). Besides, the INC strategy increased the share of broadleaved species and resulted in a synergy with recreation and timber production, and a trade-off with carbon sequestration and protection function. Our approach emphasized the disproportionally higher disturbance predisposition under the RCP8.5 climate change scenario, which may threaten currently unaffected mountain forests. Decision support systems accounting for climate change, disturbance predisposition, and BES can help coping with such complex planning situations.

Bryophyte community responses 20 years after forest management in boreal mixedwood forest

Sustainable forest management relies on a diversity of harvesting practices to conserve the variety of stand structures and compositions found in natural forests. Extensive use of clearcuts can homogenize stand structure by removing all the canopy, damage forest soils and destroy older downed woody debris already present within stands. In contrast partial cuts maintain some standing overstory and conserve certain biological legacies like large live trees as well as standing and downed dead wood, and thus should better conserve biodiversity. However, given the large number of species potentially affected by harvest operations, balancing harvesting intensity and conservation of biodiversity requires a clear understanding of habitat requirements of resident organisms and species conservation post-harvest. We examined the impacts of increasing intensities of stem removal (33%, 40%, 66% and 100%) 20 years after harvest on bryophyte communities in three stand types common in the succession sequences of Eastern boreal mixedwood forests that were dominated by trembling aspen, mixedwood and conifers. While many generalist and common forest species were shared among all harvesting levels and forest types, more specialized species like liverworts differed strongly between uncut and clearcut stands and less between uncut and partial cut stands. Bryophyte species in hardwood dominated stands tolerated more fluctuations in environmental conditions than species in mixed stands. We were unable to find habitat specialists typically associated with coniferous stands and may be related to prior outbreaks of spruce budworm that occurred 30 years ago. Our results highlight how harvest intensity and forest stand type interact to affect bryophytes and how intact stands may be required to conserve many species that are sensitive to any degree of harvesting.

Bed-scale impact and recovery of a commercially important intertidal seaweed

As the value of ecosystem-based management (EBM) approaches is increasingly recognized in marine ecosystems, it is critical that the impacts of resource harvest are assessed at various spatial scales. This is particularly true for habitat-forming resources, such as wild seaweeds, that act as foundation species by physically structuring ecosystems. The impacts of spatially heterogeneous harvest may change with scale, and have different management implications based on the ecosystem process or organism under consideration. Ascophyllum nodosum (hereafter rockweed) is a canopy-forming fucoid seaweed endemic to rocky coastlines in the North Atlantic Ocean that has been harvested for centuries. We conducted a Before-After Control-Impact study of commercial rockweed harvest at 38 sites across the coast of Maine (USA) from 2018 to 2020 in an effort to understand impact and one-year recovery of two rockweed bed structural characteristics, height and biomass, at a scale similar to a single harvest event. Our results indicate that rockweed harvest is spatially heterogeneous at the scale of the rockweed bed, and as a result, the effect sizes of harvest at this scale are smaller than those reported in previous studies that assessed smaller spatial scales. Mean rockweed biomass recovered to pre-harvest values after one year of recovery, but mean rockweed height remained lower at impacted sites. While post-harvest recovery was generally high in our study, sites that experienced higher intensities of harvest were less likely to fully recover height or biomass one year post-harvest. Our findings provide resource managers with a bed-scale perspective that can inform EBM approaches, particularly for population-level management of harvested resources and impacts of harvest on highly mobile organisms—such as birds and fish—that interact with these ecosystems at larger spatial scales.

Periodic harvests, rather than passive conservation, increase the carbon balance of boreal forests much more in Northeast China

Proper forest management can significantly contribute to global or regional carbon neutrality goals; however, the effects of different harvesting strategies on the carbon balances of forest sectors are still not clear. The motivation of this study was to develop a simulation–optimization system that can concurrently maximize the total economic benefits from timber production, biofuel production, and carbon balancing under four alternative harvesting scenarios. The current strict protection strategy (NoCutting) in this region was set as the reference scenario, and the NoConstraints and EvenFlow scenarios were generated based on whether they included restrictions on the flow of harvest volume over time. A final scenario (PreDefine) was inspired by the management policy that was implemented in this region prior to the 2010s. The scenarios were applied to a 123,400 ha boreal forest in Northeast China over a 100 year horizon. All relevant carbon pools within the forestry sector, as well as the avoided emissions related to the substitution effects of using wood products and biofuels, were considered. The results indicated that increasing harvesting intensities significantly improved the carbon balances (1.6 to 5.1 times greater), carbon stock (1% to 7.1% greater) and profitability (1.33 to 4.95 times greater), during which scenario EvenFlow was the first-rank harvest scenario. Hereinto, the carbon balances of the forest under EvenFlow were increased by 0.57 ton ha−1 yr−1 in total, during which the net atmospheric benefits from forest ecosystems, wood productions and substitutions were approximately 0.05, 0.24, and 0.38 ton ha−1 yr−1, respectively, while approximately 0.09 and 0.01 ton ha−1 yr−1 were lost by using the bio and fossil fuels, respectively, during the planning period when compared with NoCutting. The sensitivity analysis revealed that both carbon prices and substitution rates have positive effects on the total carbon balances, while significant negative effects were observed for discount rates. Overall, our results highlighted that periodic harvests rather than passive conservation should be a priority for the sustainable management of boreal forests in Northeast China.

STUDIES ON THE SPECIES PRIMULA OFFICINALIS HILL. FOR THEPURPOSE OF ESTABLISHING ECOLOGICAL CULTIVATION TECHNOLOGY

These researches were carried out in order to introduce the species Primula officinalis into the culture and to establish an ecological cultivation technology.
 The species Primula officinalis Hill., synonymous with Primula veris L., popularly known as cowslip, common cowslip or cowslip primrose, is a perennial, herbaceous species, being one of the 400 species of the Primula genus. In some countries from Europe, this species is on the verge of extinction, due to intensive harvesting from the spontaneous flora, grazing, deforestation and alpine herbicides. In Romania, Primula grows spontaneously, starting from the lowlands, on hills, pastures, alpine meadows, up to approximately 2300 - 2400 m altitude. It is known in folk medicine as having multiple phytotherapeutic uses. Primula has been used since the Middle Ages for the treatment of gout, headaches, migraines. The saponins found in the rhizomes and flowers are used in the phytotherapeutic treatment of bronchitis and colds due to their expectorant effects. The paper presents results regarding the influence of the nutrition space on some elements of growth and development in the species Primula officinalis, with a determining role in the amount of vegetable mass obtained.

Identifying priority protection areas of key food resources of the giant panda.

Animals that live in seasonal environments adjust their reproduction cycle to optimize seasonal forage quality. Giant pandas ( Ailuropoda melanoleuca) are seasonal altitudinal migrants that feed on bamboo shoots and leaves with different nutritional quality. However, the importance of bamboo shoots to giant pandas, especially small and isolated populations, is not fully appreciated. Here, we explored whether mating time of giant pandas is shaped by bamboo shoot phenology. We also assessed the intensity of ongoing bamboo shoot harvesting by local communities in 42 giant panda reserves based on questionnaire surveys. Varying intensity and protection levels of bamboo shoot harvesting were found. From these data, we developed a priority ranking scheme of protection areas for this key food resource. Our study showed that pandas time their mating behavior to coincide with bamboo shoot phenology due to the high nutritional demands associated with mating and pregnancy. We also found that bamboo shoots were not well protected in many places. Liangshan, Daxiangling, and Xiaoxiangling, containing the most isolated panda populations, were identified as the areas with the most urgent need of protection. Furthermore, equal attention should be paid to the QiongL-B population, as this region holds considerable potential to serve as a corridor between the Minshan and Qionglai populations. To address the challenges posed by bamboo shoot harvesting, we recommend establishing more practical bamboo shoot management policies, increasing public awareness of bamboo shoot protection, and providing alternative sources of income for local communities.

Below canopy evapotranspiration in four different variable retention harvesting treatments in a red pine plantation forest

AbstractVariable retention harvest (VRH) is a silvicultural approach that retains differing proportions and patterns of canopy trees across a harvested area to emulate natural disturbance effects on stand structure and enhance the resilience of the regenerating stand to abiotic and biotic stresses. Four VRH treatments were applied to an 83‐year‐old red pine (Pinus resinosa Ait.) plantation forest in the Mixedwood Plains Ecozone of Canada that included 55% aggregate retention (55A), 55% dispersed retention (55D), 33% aggregate retention (33A), 33% dispersed retention (33D) and an unharvested control (CN). In the sixth growing season after harvest, tree stem sap flow and eddy covariance flux measurements were used to examine the impacts of VRH on the dominant components of total stand evapotranspiration (ET), i.e., canopy transpiration (TC) and water flux from the understory vegetation and soil (ETU) as well as understory and canopy water use efficiency (WUE). A positive relationship was found between harvest intensity and the growth of understory vegetation and ETU. The contribution of ETU to ET was higher in the dispersed compared to the aggregate VRH treatments. Canopy transpiration contributed 83% of ET in the CN plot and 58%, 55%, 30% and 23% in the 55D, 55A, 33A and 33D treatments, respectively. Overall, VRH treatments resulted in increased canopy WUE but little comparative effect on understory WUE. Our results suggest that the dispersed retention pattern led to higher ET and productivity than the aggregate pattern of the same retention level. Where carbon sequestration and climate change mitigation is the primary management objective, higher retention levels such as 55D might be used to favour stand level carbon storage while accepting slower rates of understory development. Our findings on the effects of VRH on productivity and WUE of the canopy and understory will help forest managers to better employ VRH as an option to meet multiple objectives and adapt forests to a warmer, more variable climate.

Effects of forest management on the conservation of bird communities in eastern North America: A meta‐analysis

AbstractForest management affects conditions for both early‐ and late‐seral organisms, and managers and conservationists require information for balancing the ostensibly opposing habitat needs of both these guilds. We conducted meta‐analyses that examined silvicultural systems with a range of postharvest retention and their impacts on mature‐forest and shrubland bird species densities in eastern North America during the breeding season. Densities of mature‐forest bird species generally declined as canopy tree retention and basal area decreased, although some mature‐forest species had similar densities among unharvested and partially harvested (e.g., first‐entry shelterwood) stands, and others had their highest densities in shelterwoods. We conducted a previous meta‐analysis study, which showed most shrubland bird species in the region increase with harvest intensity, but some shrubland species had similar densities in clearcuts and shelterwoods. Given the contrasting effects of harvest intensity on the two avian guilds, we used Partners‐in‐Flight conservation values to generate objective community‐wide conservation indices relative to postharvest tree retention. Clearcuts and shelterwoods typically had the highest conservation values, and unharvested and lightly thinned stands (70%–100% tree retention) had the lowest conservation scores. Many declining shrubland bird species of conservation concern are abundant in low‐retention stands, thus elevating the conservation value of these stands. Additionally, high conservation values of harvested stands with 40%–70% tree retention represent the presence of both shrubland and mature‐forest species; the latter are potentially responding to enhanced understory structure needed for avian nesting or foraging. In contrast, contemporary closed‐canopy forests in eastern North America are generally characterized by low structural diversity and are mid‐seral stands due to historical patterns of land use and tree harvesting. Although avian community conservation values were lowest in high‐retention stands and many other threatened, non‐avian taxa depend on open‐canopy, managed forests, managers should note that late‐seral, unharvested stands can provide important habitat for old‐growth‐dependent taxa and any intensive forestry should also take into account other factors. Considering the growing interest in using postharvest retention of canopy trees to meet ecological objectives, our novel synthesis can assist managers in assessing species‐specific and community‐wide avian responses to tree retention levels along the entire gradient of canopy treatments.

Actual State of Population and Harvesting of the Baltic Shrimp Palaemon adspersus (Decapoda, Palaemonidae) in the North-Western Section of the Black Sea

Data on the sex and size-mass composition of the Baltic shrimp <i>Palaemon adspersus</i> Rathke, 1837, population were obtained basing on the analysis of samples from 35 fyke net catches in the north-western section of the Black Sea over 2017-2020. The Baltic shrimp in the catches was represented by the specimens 20-65 mm long, and the main portion (52%) was formed by the specimens 40-50 mm long. According to LBB model, over 2017-2020 the relative fishing mortality level increased from 0.7 to 1.2. At the same time, in 2020 relation of the actual biomass to the biomass ensuring the maximum sustainable yield <i>(B/B</i><sub>msy</sub>) was equal to 1.0, indicating the optimal intensity of the Baltic shrimp harvesting in the Ukrainian waters. According to the model calculations, the minimal allowed length for harvesting should be 35 mm. Analysis of the fyke nets catches revealed significant number of undersized specimens of the commercial and protected fishes in the bycatch, including juveniles of gobies, turbot and flounder. Actual harvesting intensity do not result in <i>P. adspersus</i> overfishing in Ukrainian waters. In order to mitigate the negative impact of shrimp harvesting on the non-target species, it is necessary to regulate it by limitation of the fishing gears number and optimization of their designs. It was revealed that the fyke nets number in the Ukrainian waters should be limited to about 800 units.

Сепарация очесанного зернового вороха на решетчатом днище наклонной камеры комбайна

Using the grates of a combine feederhouse and directing the grain heap for cleaning, bypassing the threshing unit, we can reduce both the energy intensity of harvesting and the degree of grain crushing. The study purpose is to compare two variants of the combine feederhouse grates: with longitudinal holes of a finite length and transverse bars between them and with through holes without transverse bars. For a preliminary assessment, a theoretical model of the separation process is proposed, which includes the slipping of combed heap layers moved by a conveyor scraper into the hole at the angle of repose. Previously, it was assumed that upon contacting with a transverse bar, the corresponding heap layer completely stops slipping and the process resumes only after overcoming the edge of the next hole. As a result, the separation rate should significantly decrease. The upgraded version of the model takes into account the inertia effect on the sliding upper heap layer, which is activated by the friction force of its lower part acting along the bar surface. As a result of the total effect of the rolling force and the inertia force, the flow direction of the upper layer components changes to become nearly horizontal, as a result of which 50 to 60% of the layer slides into the next hole without stopping. According to the theoretical model, the separation of combed grain heap should be reduced by 4 to 5% if there are 120 mm long bars between the longitudinal holes and the total length of the separating part of the grates surface is 800 mm. As a result of a laboratory experiment on the Moskovskaya 56 wheat variety, the separation of a combed grain heap decreased by 4.6% due to transverse bars, which confirmed the adequacy of the theoretical hypothesis.

Intensive harvesting menaces trees producing fodder, edible fruit, and gum in Abu Gadaf natural reserved forest, Sudan

Intensive harvesting menaces trees producing fodder, edible fruit, and gum in Abu Gadaf natural reserved forest, Sudan

Spatial trade-offs between ecological and economical sustainability in the boreal production forest

Economically-oriented forestry aims to sustain timber harvest revenues, while ecologically-oriented management supplies suitable habitat for species using deadwood as primary habitat. As these objectives are conflicting, planning for economic and ecological sustainability involves compromise and trade-offs. We analyze the spatial trade-offs between the economic value from timber harvesting and the volume of deadwood in the boreal forest. We assess these trade-offs from three perspectives: (1) landscape characteristics, affected by conservation strategies; (2) forest management promoting either economic or ecological values; (3) uncertainty in inventory errors undermining the estimate of the two sustainability objectives. To reveal the tradeoffs between the forest economic and ecological values we simulated and optimized a production landscape in Finland 30 years into the future accounting for uncertainty in biomass and deadwood inventories. We found that, with a limited reduction in timber harvesting (7%), (i) the amount of deadwood increased more in non-aggregated (45%) than in aggregated (16%) stands, (ii) constraining stands in adjacent areas further increased deadwood (21%) respect to the matrix and (iii) 7% of connected stand area harbored ≥20 m3/ha deadwood supporting survival of near-threatened species. Our results demonstrate that the structure of the landscape for biodiversity can be improved with limited economic losses. However, improving habitat configuration requires larger economic losses than only increasing habitat amount, but its ecological benefits are larger both for common and red-listed species. We found that management oriented towards stand aggregation not only creates connected areas with high deadwood of high value biodiversity but also improves the value of the whole matrix by decreasing intensive timber harvesting and energy wood collection. Finally, we found that uncertainties alter the estimate of the potential of the forest landscape to supply deadwood, and this can affect the choice of management actions to allocate over the landscape. To conclude, our results demonstrate the trade-offs between economic forest use and conservation are affected differently by landscape characteristics, forest management and uncertainty in inventory errors. As such these drivers should be considered when optimizing the forest for multiple uses.

The rate of moisture release of alfalfa and its mixtures with cereal grasses under dynamic flow flattering

Purpose. To experimentally substantiate the effectiveness of the processes of mowing alfalfa and alfalfa-cereal mixtures with mower-conditioners with a roller and hammer types working bodies. Methods. The research was carried out in the technological process of intensive harvesting of pressed hay into rolls with the use of a trailed mower-conditioner with side traction, equipped with chevron ribbed rollers and metal vshaped hammers. Raw material: freshly cut green mass of alfalfa in the phase of budding-the beginning of flowering; alfalfa-cereal mixture (perennial ryegrass ‒ at the beginning of earing), the share of cereal grasses ‒ 22.4-36.8% of dry matter. Results. It was established that the indicators of the intensity of dehydration for alfalfa in pure crops were 1.66-1.81%/h; alfalfa-perennial fenugreek mixture ‒ 1.24-1.48%/h (I and II mowers), drying time in optimal weather conditions ‒ 3 days. The technology of active field drying of leguminous grasses with the use of a disc mower-tender with roller and bitter working bodies involving wideband stacking of the mass for drying, significantly accelerated the rate of moisture release of leguminous grasses and mixtures. Harvesting technology involves: mowing with a disc mower with flattening and stacking of the mass in a wide-band roll; one-time turning at 60-65% humidity; introduction of preservatives. The capacity of the rolls when mowing according to the technology variants was: for the Sinyuha variety alfalfa ‒ 12.9 kg/running m, for the alfalfa-cereal mixture (with perennial fenugreek of the Ruslana variety) ‒ 15.3 kg/running m. Conclusions. To intensively increase the rate of field moisture transfer of the green mass of alfalfa and its mixtures with perennial fenugreek, it is advisable to use the process of the stream dynamic flattening (under favorable weather conditions) and combine it with wide-band stacking. The prepared pressed bean hay is suitable for long-term storage and can be used in feeding all sex and age groups of ruminants.

Pool Formation and The Role Of Instream Wood In Small Streams In Predominantly Second-growth Forests.

Extensive and intensive forest harvesting during the 20th century often had, and continues to have, negative impacts on stream structure and ultimately fish. Loss of instream wood and pools has been identified as a pathway by which riparian forest management can negatively impacts salmonids. Passive riparian restoration (allowing forests and streams to recover through natural processes) through the use of riparian buffers when conducting forest harvests has often been employed to promote stream habitat recovery. In this study, we evaluate the effects of 25 years of passive restoration on instream wood and pool recovery in 74 reaches in small streams (1st through 3rd order) across three channel types (pool-riffle, step-pool, and cascade) in a predominantly second-growth forest. Gradient and stream size were the most important variables for determining pool density, while stream size was the most important variable for determining pool depth. Instream wood formed 39% of pools in pool-riffle, 30% of pools in step-pool and 25% of pools in cascade channels types. Instream wood volume had a significant (R2 = 0.261, P ≤ 0.001) positive relationship with pool volume in wood-formed pools. Dimensions of individual wood pieces were associated with their likelihood of pool formation: for each additional 1 meter length within the bankfull channel the odds of forming a pool increased by 25.6%, and for each additional centimeter in diameter the odds of pool formation increased by 2.0%. When compared with studies conducted in both second- and old-growth forests, we concluded that streams associated with second-growth forests hadve both reduced densities and sizes of instream wood and pools. Young forests are likely continuing to negatively impact stream habitat and fish populations. Because riparian zones in many forests are now dominated by relatively young forest stands, and given the timeline for recovery using passive restoration alone (e.g., 100 s of years in Pacific Coastal forests), active restoration could be explored to accelerate instream wood and pool recovery.