Partial Harvesting Research Articles

Windthrow in riparian buffers affects the water quality of freshwater ecosystems in the eastern Canadian boreal forest

Despite the wide application of riparian buffers in the managed boreal forest, their long-term effectiveness as freshwater protection tools remains unknown. Here, we evaluate windthrow incidence in riparian buffers in the eastern Canadian boreal forest and determine the effect of windthrow on the water quality index of the adjacent freshwater ecosystems. We studied 40 sites—20 riparian buffers, aged 10 to 20 years after harvesting and 20 control sites within intact riparian environments—distributed among clay and sandy (esker) soils and black spruce (Picea mariana) and jack pine (Pinus banksiana) stands. We observed more windthrow in the harvested stands (36%) relative to the control sites (16%), regardless of substrate and species. We determined that the most important factors explaining windthrow were exposition, harvesting, aquatic environment size, and stand characteristics. These factors drive wind exposure, speed, and force, which determine post-harvest windthrow risk. Furthermore, windthrow negatively affected the water quality index of the adjacent aquatic systems, i.e., greater windthrow decreased the protective effect of the riparian buffer. We recommend increasing the use of partial harvest near riparian environments and adapting riparian buffers to site conditions to ensure the long-term protection of adjacent freshwater ecosystems.

Bioeconomic analysis of deterministic and stochastic partial harvesting in the production of spring genetics tilapia variety restricted to minimum market sizes

A bioeconomic model was used for commercial tilapia culture to evaluate different partial harvest strategies. This study considered homogeneous and heterogeneous seeding sizes. The impact of one and two partial harvests was evaluated. In the first case 25% of the population was harvested (I), in the second 50% (II), in the third 25% and 25% (III), and in the fourth 50% and 25% (IV). Four minimum market sizes were considered: 350, 400, 450, and 500 g. The results indicated that a first partial harvest of 25% or 50% of the population as well as two partial harvests with a homogeneous seeding sizes generated the highest net benefits, with US$3954.32 and US$4303.52 at a minimum market sizes of 500 g. Mortality rate, mean water temperature, feed cost and product price were considered as sources of uncertainty and were simultaneously analyzed in the bioeconomic model using Monte Carlo analysis. An initial partial harvest of 25% of the population followed by two partial harvests with a homogeneous seeding sizes and a minimum market sizes of 500 g presented the lowest uncertainty and an expected loss of 32.84% and US$0.00, respectively. An initial partial harvest of 50% of the population as well as a partial harvest with a heterogeneous seeding sizes presented the lowest uncertainty (31.97%), while two partial harvests with a homogeneous seeding sizes presented the lowest expected loss of US$-2.09, in both cases with a minimum market sizes of 500 g. It provides relevant information to the producer for decision-making in the management of seeding and harvesting, to improve their economic, considering minimun market sizes.

Increase in forest structural complexity along a precipitation gradient is mediated by partial harvests in temperate Patagonian forests

Increasing forest structural complexity is becoming a common goal in forestry worldwide. However, the lack of empirical quantification clouds its implementation. Here we quantified the long-term effects (> 30 y) of partial harvest on stand structural complexity and net primary productivity using the east–west precipitation gradient (318–2508 mm, mean annual precipitation-MAP) of western Patagonian as a study system. In this gradient, pairs of 1-ha plots on 20 sites (20 plots harvested and 20 plots unharvested) were installed. In each plot terrestrial laser scanning was used to quantify the stand structural complexity index (SSCI), and Sentinel satellite images to obtain the Enhanced Vegetation Index (EVI: proxy of net primary productivity). Generalized linear mixed-effect models were used to relate SSCI to MAP and EVI to SSCI, with harvesting as indicator variable, and site as random variable (two plots nested to same precipitation). Results showed that harvested plots on mesic-to-humid sites (but not on dry sites) had higher SSCI and EVI values compared to unharvested plots, likely due to a greater vertical canopy packing. These results show the influence of precipitation on SSCI, which resulted in a more diversified stand structure and higher EVI. Such insights support site-specific management aimed to increase forest structural complexity.

Evaluation of growth performance, carcass yield, and proximate composition of fillets of male and female pirarucu (Arapaima gigas) during the fattening phase

The objective of this study was to evaluate the comparative growth performance, carcass yield, and the proximate composition of the muscle between male and female Arapaima gigas (pirarucu) during the fattening phase. Juvenile pirarucu (n = 114; 1126 ± 219 g; 55 ± 3 cm) were kept in 120 m2 brick tanks at a stocking density of 1.55 g m-2. Fish were raised under the same management conditions during 427 days and biometrics were performed monthly to evaluate the growth performance. Fish (n = 15 per collection day) were sampled at 91, 187, 273, 341 and 427 days to evaluate the carcass yield, proximate composition of the muscle and to determine its gender via histological analysis of the gonads. Data were analyzed using a multivariate statistical method. Growth performance, carcass yield and proximate composition of the muscle were similar between genders up to 427 days of rearing. The coefficients of variation in total weight and length that express the batch heterogeneity were higher for females throughout practically the whole experimental period. This was probably due to the dominance behavior between female fish, which also justifies why some females reached larger sizes at the end of the experiment. The yields for the fillet, abdominal muscle and loin were greater at 273 days compared to other sampling events, regardless of gender. Partial harvesting of pirarucu during the fattening phase can therefore be a management strategy for slaughtering fish with a higher meat yield.

The influence of clearcut harvesting on bird communities in an adjacent protected area in Nova Scotia: Implications for buffer implementation

Human activities adjacent to protected areas have been intensifying as human population grows, with protected areas in some regions effectively becoming islands within a sea of human development. Studies examining the effects of forest harvesting and deforestation on the biodiversity of adjacent protected areas have primarily focused on study areas within the tropics. Due to concerns about impacts of low-retention or clearcut harvesting on biodiversity in adjacent protected areas, the province of Nova Scotia implemented interim harvesting guidelines adjacent to all parks and protected areas in 2019. To examine the effectiveness of these guidelines, we designed a study to quantify the relative influence of previous clearcut harvesting immediately adjacent to Cloud Lake Wilderness Area based on changes in bird communities along transects beginning 100 m inside clearcuts and extending 300 m into the protected area. Ordinations revealed clear differences in the bird communities among transect points; clearcut and edge bird communities differed significantly from those 200 and 300 m inside the protected area and those 100 m inside the protected area comprised of a blend of species from the other 4 transect point locations. Overall species richness and many individual species abundances reflected this pattern as well - 13 species with clear responses across transect point locations were intermediate in abundance at sites 100 m into the protected area. The weight of evidence from our study supports other research showing that the zone of influence from clearcut harvesting on passerine birds in adjacent forest is at least 100 m for many species. These results suggest that a minimum harvesting and development buffer adjacent to protected areas of between 100 and 200 m would be a reasonable management approach if the objective is to minimize the effects of these activities on the bird communities within protected areas. To determine if a partial harvest within the buffer would maintain biodiversity within a protected area will require additional research that directly compares the influence of partial harvesting to no-harvest prescriptions on a variety of taxa. Additional studies in other protected areas that vary in size and have dissimilar landscape contexts, habitat conditions, and bird communities could provide further insight.

Trunk Muscle Function and Core Stability in Women Who Had Muscle-Sparing Pedicled Transverse Rectus Abdominis Myocutaneous Flap Breast Reconstruction.

The long-term effects of the unilateral muscle-sparing pedicled transverse rectus abdominis myocutaneous (TRAMmsp) flap procedure on trunk muscle performances and core stability were investigated in women with breast cancer. Forty women (mean age = 42.6years) who had received breast reconstruction with the unilateral TRAMmsp flap procedure no less than 6months earlier (mean = 10.3 [standard deviation, SD = 4.9] months) (TRAM group) participated, and 30 women who were healthy and matched for age (mean age = 41.2years) served as controls (control group). Their abdominal and back muscle strength was assessed using the curl-up and prone extension tests, respectively, and their static abdominal muscle endurance and back extensor endurance were assessed using the sit-up endurance test in the crook-lying position and the Biering-Sørensen test, respectively. Core stability strength was assessed using a 4-level limb-lowering test (abdominal muscle test), and core stability endurance was assessed while lying supine with both flexed legs 1 inch off the mat while keeping the pelvis in a neutral position with a pressure biofeedback unit. Compared with the control group, trunk muscles of the TRAM group were weaker, showing less endurance, as were their core stability strength and endurance. Static trunk muscle endurances and trunk flexion strength were associated with core stability in both groups. Women exhibit trunk flexor and extensor weakness along with poor endurance and impaired core stability even after an average of 10months from receiving the TRAMmsp flap procedure. Immobilization after surgery, with possible systemic inflammatory effects from surgery and chemotherapy, might have further contributed to the generalized weakness subsequent to the partial harvesting of the rectus abdominis. Women after breast reconstruction with the TRAMmsp flap procedure show long-lasting deficits of strength and endurance in abdominal muscles, back extensors, and core stability. Proactive measures including early detection and evaluation of impairments as well as timely intervention targeting these clients are important to minimize the dysfunction and support their return to community participation.

Sustaining eastern oak forests: Synergistic effects of fire and topography on vegetation and fuels.

Across much of the eastern United States, oak forests are undergoing mesophication as shade-tolerant competitors become more abundant and suppress oak regeneration. Given the historical role of anthropogenic surface fires in promoting oak dominance, prescribed fire has become important in efforts to reverse mesophication and sustain oaks. In 2000 we established the Ohio Hills Fire and Fire Surrogate (FFS) study to examine whether repeated prescribed fire (Fire), mechanical partial harvest (Mech), and their combined application (Mech + Fire) reduced the dominance of subcanopy mesophytic competitors, increased the abundance of large oak-hickory advance regeneration, created a more diverse and productive ground-layer flora, and produced fuel beds more conducive to prescribed fire, reducing the risk of high-severity wildfire. Here we report on the ~20-year effects of treatments on vegetation and fuels and examine the support for interactive effects across a topographic-moisture and energy gradient. In general, we found that Fire and Mech + Fire treatments tended to reverse mesophication while the Mech-only treatment did not. The moderate and occasionally high-intensity fires resulted in effects that were ultimately very similar between the two fire treatments but were modulated by topography with increasing fire severity on drier sites. In particular, we found support for an interaction effect between treatment and topography on forest structure and tree regeneration responses. Fire generally reduced mesophytic tree density in the midstory and sapling strata across all site conditions, while leading to substantial gains in the abundance of large oak-hickory advance regeneration on dry and intermediate landscape positions. Fire also promoted ground-layer diversity and created compositionally distinct communities across all site conditions, primarily through the increased richness of native perennial herbs. However, the fire had limited effects on fine surface fuel loading and increased the loading of large woody fuels, potentially increasing the risk of high-severity wildfire during drought conditions. We conclude that two decades of repeated fires, with and without mechanical density reduction, significantly shifted the trajectory of mesophication across most of the landscape, particularly on dry and intermediate sites, highlighting the capacity of a periodic fire regime to sustain eastern oak forests and promote plant diversity but modulated by topography.

A comparison of initial harvest results from four partial harvest systems at the Blue Heron Demonstration Forest

Demonstration forests have been established across the northern hardwoods of the United States to assess the economic and environmental implications of partial harvest systems, such as single tree selection and diameter limit cutting. Single tree selection has been studied at several sites in the northern hardwoods of Canada, but there has not been a structured comparison of partial harvest systems within one site. We assessed the initial harvest results at the Blue Heron Demonstration Forest, in which four partial harvest systems – single tree selection (STS), financial maturity selection (FMS), diameter limit cutting (DLC), and crop tree release (CROP) – and a control treatment were implemented with multiple replicates within a typical northern hardwood forest in central Ontario. DLC harvested the most volume as well as basal area, followed closely by FMS. STS harvested the least basal area and volume and generated the lowest product values as well as the lowest stumpage revenue. However, STS did not harvest significantly more low vigour trees, nor did it significantly increase the proportion of basal area that is high vigour, suggesting that alternative partial harvest systems like FMS may achieve silvicultural objectives while yielding superior financial results over multiple cutting cycles.

Clean Water Media Eel Enlargement and Breeding Training as an Effort to Increase the Entrepreneurial Capacity of the Paya Geli Village Community

Paya Geli Village is a village located in Sunggal District, North Sumatra Province and has good geographical conditions for the development of the agricultural sector, especially freshwater fish. The availability of abundant and easily available clean water has become a strength in the development of the freshwater fish industry in this village. The process of eel cultivation which does not require a lot of equipment and care as well as a large area of ​​land is the main attraction in terms of its development potential. Paya Geli village community. The people of Paya Geli Village only use a conventional cultivation system where the eels are simply left in a mud bath and fed with leftover food. The use of the conventional system will not only have a small impact on productivity but will also encourage a bad and dirty paradigm for the eel consumer society. The solution to this problem is the use of eel cultivation methods with clean water media and partial harvests which will not only increase productivity but also make it easier to control and harvest according to the specifications desired by the market. It is hoped that this service activity will not only increase the productivity of eel cultivation but also become a new source of driving the economy of the Paya Geli Village community and expand employment opportunities through eel farming entrepreneurial activities.

A systematic global review of mammalian carnivore responses to production forests

Abstract Unmodified forests are increasingly rare worldwide, with forestry a major contributor to habitat modification. Extending conservation practices beyond protected areas is important to conserve forest ecosystems. We investigate the response of native mammalian carnivores (both Order Carnivora and Family Dasyuridae) to production forests globally, including harvested native forest and timber plantations. We examine how carnivores recorded in production forests use these forests versus other land uses, particularly native and/or unharvested forest; how habitat use relates to threatened status, body size, diet and harvesting method; carnivore responses to habitat features within production forests; and carnivore denning, breeding and predation behaviour in production forests. We review 294 studies recording 132 carnivore species in production forests. Carnivores generally show higher use of unharvested native forests and lower use of agricultural land than production forests. Threatened species and large carnivores respond more negatively to production forests than non‐threatened species and small carnivores respectively. Hypercarnivores respond more negatively than omnivores to plantations compared to native forest, with no difference in the use of harvested and unharvested native forest between these dietary groups. Notably, a high proportion of carnivore species use clearfelled more than unharvested native forest. In forest with partial harvesting or reduced‐impact logging, most species show no difference in use between harvested and unharvested forest. Carnivores generally respond positively to habitat features such as riparian areas and coarse woody debris. Several carnivores were recorded denning and breeding in production forests. Production forests often influence the prey availability, hunting success and diet of carnivores. We show that many carnivores use production forests, and how they respond to production forestry varies with species traits and conservation status. We recommend that production forests are managed as valuable carnivore habitat, and highlight strategies to enhance the use of these forests by carnivores.

American beech outgrows sugar maple at the sapling stage regardless of partial harvest intensity in northern hardwood forests

Sugar maple (Acer saccharum Marsh) is a key species in the northern hardwood forests of North America and management has historically focused on promoting its regeneration and yielding high-quality timber. A decrease in the abundance of sugar maple to the advantage of American beech (Fagus grandifolia Ehrh.) has been observed over the last decades. Together with the spread of beech bark disease, the understory dominance of American beech has often resulted in depleted, low vigour forest stands (i.e., with a low proportion of healthy trees). To favour regeneration and growth of sugar maple, increasing harvest intensity of partial treatments has been suggested, but the harvest intensity required remains unclear. In this study, we monitored the radial growth of saplings in 12 northern hardwood stands located in the Province of Quebec, Canada. These were commercially harvested with removal intensities ranging from 0% to 80% of the basal area. Using generalized additive mixed models, we investigated the effect of harvest intensity on the growth response of both species. Our results revealed that American beech saplings consistently had a much stronger radial growth response than sugar maple after harvest, regardless of treatment intensity. Consequently, modulating the intensity of partial harvests cannot singlehandedly favour the growth of sugar maple regeneration where American beech saplings dominate the understory. Additional silvicultural interventions are thus needed to control advance understory beech.

Not-so-random forests: Comparing voting and decision tree ensembles for characterizing partial harvest events

Ensemble-based change detection can improve map accuracies by combining information from multiple datasets. There is a growing literature investigating ensemble inputs and applications for forest disturbance detection and mapping. However, few studies have evaluated ensemble methods other than Random Forest classifiers, which rely on uninterpretable “black box” algorithms with hundreds of parameters. Additionally, most ensemble-based disturbance maps do not utilize independently and systematically collected field-based forest inventory measurements. Here, we compared three approaches for combining change detection results generated from multi-spectral Landsat time series with forest inventory measurements to map forest harvest events at an annual time step. We found that seven-parameter degenerate decision tree ensembles performed at least as well as 500-tree Random Forest ensembles trained and tested on the same LandTrendr segmentation results and both supervised decision tree methods consistently outperformed the top-performing voting approach (majority). Comparisons with an existing national forest disturbance dataset indicated notable improvements in accuracy that demonstrate the value of developing locally calibrated, process-specific disturbance datasets like the harvest event maps developed in this study. Furthermore, by using multi-date forest inventory measurements, we are able to establish a lower bound of 30% basal area removal on detectable harvests, providing biophysical context for our harvest event maps. Our results suggest that simple interpretable decision trees applied to multi-spectral temporal segmentation outputs can be as effective as more complex machine learning approaches for characterizing forest harvest events ranging from partial clearing to clear cuts, with important implications for locally accurate mapping of forest harvests and other types of disturbances.

Growing smaller fish for inclusive markets? Increasing stocking density and shortening the production cycle of Nile tilapia in cages on Lake Victoria

Fish farmers aim to maximise fish weight relative to the feed inputs needed to turn a profit. Yet, many farmers in Africa lack the cash flow to grow large fish and many consumers prefer, or are limited to purchasing, small fish. This study aimed to intentionally produce small tilapia in cages by assessing the effects of higher stocking densities and shorter growth cycles on production and financial efficiency. An experiment with 3 treatments and 6 replicates took place on Lake Victoria. The first treatment (T1) used a stocking density of 2.9 ± 0.3 kg per m−3 and aimed to produce fish to an average body weight (ABW) of 400 g (final ABW = 500.33 ± 31.01 g after 138 days). Treatment two (T2) did the same but with double the stocking density (5.9 ± 0.3 kg per m−3), resulting in a final ABW of 439.22 ± 22.22 g over 138 days. The third treatment (T3) partially harvested 50% of the cage (after 76 days) once reaching an ABW of 230.92 ± 22.55 g. The remaining fish in T3 were on-grown for a total of 138 days (final ABW = 499.86 ± 15.95 g). A fourth production scenario (M1) based on data from T3, modelled a 100% harvest after 76 days of culture. There were no significant differences in mortality between treatments. There were no statistical differences in the feed conversion ratio (FCR) between T1 (1.51 ± 0.03) and T2 (1.49 ± 0.02), though T3 was statistically lower (1.46 ± 0.02; p = 0.03). Cages in T1 had a higher proportion of fish between 400 and 599 g while fish in T2 were mostly between 300 and 499 g. T3 had a bimodal distribution with most fish either in 200–299 g or 400–499 g. There was little effect on average price per kg for T1 (3.0 ± 0.01 USD) and T2 (2.98 ± 0.01 USD), though T3 (2.89 ± 0.04 USD) was significantly lower (p = 0.001). Overall, T2 had significantly higher gross margins (17% ± 2.08) than T1 (13% ± 2.3, p = 0.021) and T3 (7.2% ± 2.43, p = 0.001), while M1 had the lowest gross margins (−11.8% ± 5.5). The results suggest that farmers can increase stocking densities. Some farmers can use partial harvesting strategies or shorter cycles to produce small tilapia and achieve faster cash flows, though the economic margins are lower. Such approaches can provide opportunities for poorer farmers and consumers.

Homestead mechanized aquaculture in Bangladesh: New concept for enhancement for production and profitability

In Bangladesh, almost all of the homestead ponds are cultured extensively, where there are scopes to enhance productivity through aquaculture mechanization. Five household-sized ponds (60±0.02 decimal) were selected. No mechanization is done on Pond 1. Pond 2, Pond 3, Pond 4 and Pond 5 were equipped with surface aeration; Pond 3 was with Bottom aeration; Pond 4 and Pond 5 were equipped respectively with surface, bottom, combination of both and combination of both aerations along with additional automated feed sprayer. All ponds were stocked at a rate of 250 pcs. /decimal mono-sex Tilapia (Oreochromis niloticus) and the stocking size was 0.90±0.15 g. Water Temperature, pH, and dissolved oxygen (DO) were recorded two times daily, whereas Ammonia, Nitrate, Nitrite and Phosphate data were recorded fortnightly during the 124-day culture period. Highest average growth (266.08±12.80 g) and lowest Feed Conversion Ratio (1.10) were found in Pond 5, whereas the lowest average growth (153.70±48.07) and highest FCR (1.70) was found in Pond 1. Production was enhanced by 40%, 28%, 47% and 54% respectively in Pond 2, 3, 4 and 5; compared with the control Pond 1. Economic analysis showed that the profit increased by 13%, 25% and 41% in Pond 2, 4 and 5 respectively compared with control Pond 1. In Pond 3, profit decreased by 25% compared with control Pond 1. In all treatments, FCR is reduced, which is very important to maintain good water quality for homestead ponds. Economically These experiments need to be further developed for polyculture ponds, to find out the appropriate species combination, to serve partial harvest for household consumption and for more viable economic return.

Species identity and tree size drive residual tree mortality in island remnants in burned and harvested boreal forests

Ecosystem-based Forest Management (EBM) is a global paradigm with different forms of implementation. In North America, a key aspect of EBM is the emulation of natural disturbances such as wildfire, with retention forestry representing one dominant approach to implementation. Retention is intended to reduce the contrast between ecological legacies present in fire-disturbed and harvested stands by leaving unharvested patches or “island remnants”. These island remnants provide refugia for forest species, accelerate forest regeneration, and supply coarse woody material over time. However, the objectives of leaving retention patches could be compromised by excessive post-disturbance tree mortality, which may erode canopy cover in patches. Comparisons of residual tree mortality in dispersed retention or partial harvest to reference forests and clearcuts exist, but rarely have comparisons to island remnants created by wildfires been made, despite this being the model for these patches. Here, we sampled island remnants in burned and harvested areas in aspen-dominated mixedwood forests in Alberta, Canada, a decade after disturbance. We sought to: (i) test for differences in post-disturbance tree mortality in island remnants (fire versus harvest) (ii) determine if forest island edges experience higher tree mortality than plots located in the interior, and (iii) examine whether tree species, tree size, and stand density influence tree mortality patterns. Post-disturbance tree mortality was quantified using visual field surveys. Additionally, we dated a sub-sample of trees to quantify temporal patterns of tree mortality. We found that harvest-created island remnants did not exhibit higher residual tree mortality than similar-sized fire island remnants. Edge effects also had no impact on tree mortality, irrespective of disturbance type. Aspen (Populus tremuloides) had higher mortality than spruce (Picea glauca), and small-sized trees had a higher probability of mortality than large-sized trees. While previous studies have reported elevated rates of mortality for retention trees in relation to reference stands, we found similar mortality rates for trees in fire and harvest island remnants. These results support the continued implementation of retention forestry using island remnants within the scope of EBM in Alberta to promote forest recovery and resilience following disturbances.

Growth response and survival of American beech, yellow birch, and sugar maple regeneration to partial harvest

In northern hardwood stands, silvicultural treatments aimed at regenerating sugar maple and yellow birch, such as site preparation and mechanical control of American beech saplings, often results in the formation of dense thickets of beech regeneration. The objective of this study was to compare the growth and survival of beech regeneration originating from stump sprouts, root suckers and seedlings, with yellow birch and sugar maple regeneration in partially harvested stands under cervid browsing pressure. Over an eight-year period, 997 individuals of the three species were monitored in three northern hardwood stands dominated by sugar maple, yellow birch, and American beech in Quebec, Canada. Each stand included replicates of four partial harvesting treatments and a control, providing a gradient of light and competition conditions. Beech stump sprouts and root suckers had higher growth and survival probabilities than seedlings of all three species under all light and competition conditions. Results suggest that treatments triggering beech sprouts should be applied with caution and under conditions that ensure sufficient survival and development of desired species. This study also provides evidence that selective browsing by cervids could be an important overriding factor exacerbating the effect of beech competition on yellow birch regeneration.

Carbon footprint values as a climate change assessment criterion of the partial harvests of European seabass and meagre in earthen pond aquaculture

Abstract Turkey's Mediterranean aquaculture industry is the world leader in European seabass aquaculture and the European leader in meagre aquaculture. In this study, carbon footprint (CF) values of four partial harvests of European seabass in earthen pond aquaculture (EPES) and meagre in earthen pond aquaculture (EPM) were determined. The average values of total CF expended for EPES and EPM, which reached a final harvest weight of approximately 1,500 g in 1,061 and 633 days were 3.38 and 2.26 kg CO2e kg−1, respectively. The lowest and highest rates of CF expended on consumed compound diet (CFCD) were 63.92 and 65.59% in EPES, and 62.44 and 66.70% in EPM, respectively. The rates of CF general management were 32.0 and 33.57% in EPES and 30.98 and 34.98% in EPM, respectively. Against this high proportion of the compound diet, the second highest value was the lowest and highest proportion of partial harvests of electricity, 28.20 and 29.59% in EPES and 27.09 and 30.51% in EPM, respectively. CF input and CF output per kg values of meagre were decreased with increasing weight, therefore meagre can be defined as a species with high global food security and resilience against climate change.

Simultaneous CAS9 editing of cpSRP43, LHCA6, and LHCA7 in Picochlorum celeri lowers chlorophyll levels and improves biomass productivity.

High cellular pigment levels in dense microalgal cultures contribute to excess light absorption. To improve photosynthetic yields in the marine microalga Picochlorum celeri, CAS9 gene editing was used to target the molecular chaperone cpSRP43. Depigmented strains (>50% lower chlorophyll) were generated, with proteomics showing attenuated levels of most light harvesting complex (LHC) proteins. Gene editing generated two types of cpSRP43 transformants with distinct lower pigment phenotypes: (i) a transformant (Δsrp43) with both cpSRP43 diploid alleles modified to encode non-functional polypeptides and (ii) a transformant (STR30309) with a 3nt in-frame insertion in one allele at the CAS9 cut site (non-functional second allele), leading to expression of a modified cpSRP43. STR30309 has more chlorophyll than Δsrp43 but substantially less than wild type. To further decrease light absorption by photosystem I in STR30309, CAS9 editing was used to stack in disruptions of both LHCA6 and LHCA7 to generate STR30843, which has higher (5-24%) productivities relative to wild type in solar-simulating bioreactors. Maximal productivities required frequent partial harvests throughout the day. For STR30843, exemplary diel bioreactor yields of ~50 g m-2day-1 were attained. Our results demonstrate diel productivity gains in P.celeri by lowering pigment levels.

Partial cutting favours northern white-cedar regeneration but does not ensure recruitment to canopy: does browsing matter?

Abstract Gap dynamics facilitate recruitment of late-successional species such as northern white-cedar (Thuja occidentalis L.). For this reason, harvests that result in partial rather than complete canopy removal have been suggested for cedar. However, success of regenerating cedar following partial harvests is uncertain, especially where there is heavy browsing by white-tailed deer (Odocoileus virginianus Zimmerman) or snowshoe hare (Lepus americanus). Efforts to understand how partial harvests and browsing interact to affect natural regeneration of cedar have been limited. We inventoried partially harvested stands along a gradient of 1–11 years since harvest in New Brunswick, Canada, in an area where deer frequently overwinter. Cedar regeneration was negatively influenced by browsing, but positively influenced by years since harvest and sapling basal area. Cedar seedling survival was assessed over a 2-year period and found to be primarily a function of height at initial measurement, with little influence of browsing. Annual vertical gain of cedar seedlings (a surrogate for height growth) decreased with increasing years since harvest and was influenced by distance from gap edge. In gaps, vertical gain increased with distance to gap edge, while distance to gap edge had a negative influence on vertical gain of seedlings in the matrix (between-gap areas). Many tagged cedar seedlings disappeared prior to remeasurement. These were likely completely consumed by browsers, limiting our ability to determine relative influences of partial harvest and browsing on cedar regeneration. We conclude that partial harvests, as applied in this study, increase cedar abundance and vertical gain, but browsing may necessitate seedling protection. We suggest monitoring to confirm sufficient cedar regeneration in partially harvested stands, using exclosures where browsing is a concern, and retaining or at least delaying removal of seed-bearing cedar overstory trees until regeneration has reached heights safe from browsing.

Partial Harvest Effects on the Forest Floor at Four Northern Hardwood Sites in the Green Mountains of Vermont, USA

Abstract Harvesting activities are known to decrease forest floor carbon pools, but the response varies with harvest intensity. We examined partial harvesting (33–55% of basal area removed) effects on the forest floor at four northern hardwood sites in Vermont, USA. Six baseline quantitative samples were taken at each site and 9–36 new locations were sampled 1.5–2.6 years after harvesting. Forest soil disturbance was estimated, and basal area was tallied pre- and post-harvest. The forest floor consisted primarily of Oi and Oe horizons. The pre-harvest site means in carbon stock ranged from 6.8 to 12.3 Mg ha-1 and were not significantly different after harvesting. The pre-harvest site means in depth ranged from 2.8 to 4.5 cm and, post-harvest, there was significantly decreased thickness at one site and significantly greater density at two sites postharvest. This compaction was also visually observed in the field. Partial harvesting, which included single-tree and group selection, created highly variable conditions that challenged our experimental design. However, the two sites with the higher number of resampling locations (35–36) had relatively low variability in forest floor metrics and showed significant responses in thickness and density. Continued monitoring is needed to determine long-term trends.