Partial Harvesting Research Articles

Tree Regeneration Structure Following Beech Bark Disease-Motivated Harvests: Factors Associated with Patterns and Management Implications

In the northern Appalachian region of North America, mortality of mature American beech (Fagus grandifolia Ehrh.) via the introduced beech bark disease (BBD) can result in dense thickets of beech saplings that inhibit the regeneration of other species. It is unknown if similar structures characterize more recently infested managed forests in the Great Lakes region. If these dense beech sapling layers do exist, management would be aided by knowing which site/regional factors they are associated with and by identifying particular sapling structures that may threaten the sustainability of these forests under current management paradigms. To examine these patterns, we used a natural experiment with sample plots in 69 unevenly aged, selection silviculture-managed, maple (Acer spp.)-dominated northern hardwood stands. Our stands were dispersed across northern Michigan, USA and had undergone BBD-motivated partial harvests favoring beech removal (mean = 5.5 years before measurement). In each stand, we quantified tree regeneration structure in relation to winter deer use (fecal pellet count density), site quality (habitat type), geographic region (Eastern Upper Peninsula and Northern Lower Peninsula), and multiple measures of overstory stand density. We also examined the density effects of taller regeneration strata on subordinate strata. Across sites, the small sapling recruit class (i.e., >137 cm tall and <5 cm diameter at 137 cm tall) was dominated by beech and was often dense (44% of subplots > 2000 stems ha−1 and 16% of subplots > 5000 ha−1) but never exceeded the > 10,000 stems ha−1 reported in the northern Appalachian region. Beech sapling density was higher in the Northern Lower Peninsula, on lower quality sites, at lower postharvest overstory densities, and on sites with higher densities of preharvest overstory beech. In contrast to the beech-dominated small sapling recruit class, seedlings (i.e., <25 cm tall) were generally more species diverse than sapling strata and were dominated by maple species. Although generally dense, seedling density was negatively related to small sapling recruit density, suggesting that saplings may suppress the seedling stratum. The general pattern for the small sapling recruit layer of browsing-insensitive beech (and ironwood, Ostrya virginiana Mill. K. Koch) dominance and low representation of browsing-sensitive species (e.g., Acer spp.) circumstantially supports the notion that regeneration structure is heavily influenced by deer. However, current deer use was generally low in our stands, and relationships with tree regeneration structure were weak. Instead, regeneration structure is likely shaped by a combination of factors operating at long time scales (i.e., legacies of deer browsing pressure, selection silviculture (given beech and ironwood are shade tolerant), overstory composition, and site quality) and by those effects that are more proximal, such as postharvest overstory density. Minimum stocking criteria for species considered desirable for management (e.g., sugar maple and Acer saccharum Marshall) suggest many stands are inadequately stocked in the sapling recruit classes. Although future regeneration dynamics are unclear, current patterns suggest that many stands with high beech/ironwood small sapling recruit densities may require management intervention to overcome insufficient recruitment of species targeted for management.

The influence of repeated prescribed fire on decomposition and nutrient release in uneven-aged loblolly\u2013shortleaf pine stands

BackgroundRepeated use of prescribed fire in Southern US pine stands has the potential to alter litter quality as well as forest floor mineralization, which may reduce nutrient availability. There are few studies that have investigated the effects of prescribed fire on litter decomposition in stands with frequent, partial harvests. To better understand the effects of the long-term use of prescribed fire coupled with periodic harvesting, we monitored foliar litter mass loss and nutrient dynamics in three loblolly pine (Pinus taeda L.)–shortleaf pine (Pinus echinata Mill.) stands located in southeastern Arkansas, USA. A reciprocal transplant method and the litterbag technique were used to determine the effects of litter source (litter quality) and litter location (environmental conditions) on decomposition.ResultsLong-term use of prescribed fire in periodically harvested stands had minimal influence on mass loss and nutrient dynamics. The proportion of foliar litter remaining after approximately 16 months did not significantly differ by litter source or location. Decay constants associated with litter incubated during the first 30 days of the study differed significantly by litter source, but thereafter were similar. Initial concentrations of phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) were 13 to 22% greater for litter originating from the burn than for litter originating from the control treatment, but differences in nutrient concentrations were not found to alter decomposition or nutrient dynamics. Thirteen percent more K was lost from litter originating from the burn compared to litter originating from the control treatment, but losses of other nutrients did not differ between litter sources. Soil and forest floor environmental conditions did not differ between treatment locations, which likely contributed to the similar decomposition rates in the two treatment locations. The rapid growth of understory and the maintenance of similar canopy conditions as a result of harvesting were likely responsible for the similarity in environmental conditions.ConclusionsRepeated dormant season prescribed fire in these loblolly–shortleaf pine stands did not appear to have a substantial influence on mass loss or nutrient release from litter. Land managers who utilize prescribed fire with periodic harvesting in relatively mesic upper Gulf Coastal Plain pine forests likely will not alter litter decomposition or nutrient dynamics.

Protecting timberland RMZs through carbon markets: A protocol for riparian carbon offsets

Riparian Management Zone (RMZ) allocations can place a burden on landowners due to restrictions (sometimes prohibitions) on harvesting. The opportunity cost for the landowner may be minimized by shifting the primary management objective in RMZs from timber production to compensation for above-ground carbon. Our primary objective was to compare long-term net revenue generating potential of RMZs under three scenarios: (I) compensation for carbon credits without harvesting; (II) partial harvesting using Best Management Practices (BMP) guidelines without carbon credits; (III) partial harvesting combined with carbon credits as per the California Compliance Offset Protocol. Basic stand data on trees of 2.5 cm and higher were collected in riparian forest plots along headwater streams within two experimental forests in the northeast US. The USFS Forest Vegetation Simulator was used to simulate growth and yield and schedule management activities over 20-year cutting cycles. Timber volumes and registry offset credits along with their market values were calculated for the respective scenarios and a Net Present Value (NPV) and Equal Annual Equivalent (EAE) analysis was performed under assumptions of constant prices and costs. The initial aboveground carbon stocks at both locations were 32% and 140% higher than the average value for their assessment areas. Having above-average carbon stocks and basal areas between 30 and 33 m2/ha, all scenarios returned positive NPVs and EAEs. The hardwood riparian forest had a higher NPV and EAE by not participating in the carbon markets and pursuing partial harvesting as per BMP guidelines (Scenario II) at lower discount rates but had higher NPVs and EAEs under carbon markets at higher discount rates (Scenario I and III). The conifer/mixed species riparian forest provided greater positive net revenue flows by participating in the carbon markets either in a no harvesting scenario or under partial harvesting as per guidelines in the Protocol (Scenarios I and III). Our results indicate that a protocol for compensating landowners with large forest holdings for riparian carbon offsets provides an opportunity to generate positive net revenues in scenarios in which state BMP guidelines may restrict harvesting in RMZs. Given the high density of ecologically critical headwater streams in the Northeast and potential RMZ restrictions, the carbon offset option provides landowners with the opportunity to remain economically viable.

Financial Assessment of Future Stand Conditions Required to Recover the Opportunity Costs of a North Louisiana Streamside Management Zone

Abstract Understanding the costs that residual habitat spaces carry into future rotations can provide managers more complete information when financially assessing timber management options that often extend for many decades. This case study assessed a streamside management zone's (SMZ) opportunity costs for a timber harvest site in north Louisiana. Timber removal occurred in summer 2018 by clearcut. A wooded buffer extending 50 feet on each side of a streambank and totaling 7.52 acres was retained; partial harvesting of pine timber was allowed. A timber inventory revealed that 99.6 tons per acre of standing hardwoods resided within the SMZ. Excluding noncommercial species placed its current present value (opportunity cost) at $1,803. Two future active management scenarios, “controlled” and “intensive,” were modeled over the next rotation at a 4 percent real discount rate, where price changes occurred at 0, 1, 2, 3, and 4 percent annually. Both management strategies consistently produced positive land expectation values (LEV) when SMZ opportunity costs were not included in the assessment. However, inclusion of SMZ protection under “controlled” management required timber price changes of 4 percent annually, while the “intensive” management option required timber price changes of at least 3 percent annually to return positive LEVs.

The Combined Role of Retention Pattern and Post-Harvest Site Preparation in Regulating Plant Functional Diversity: A Case Study in Boreal Forest Ecosystems

Changes in the light availability in forests generated by diversified retention patterns (e.g., clear cut, partial harvest) have been shown to strongly filter the plant species present. Modified soil microsite conditions due to post-harvest site preparation (e.g., mechanical site preparation, prescribed fire) might also be an important determinant of plant diversity. The objective here was to detect how retention pattern and post-harvest site preparation act as filters that explain the understory functional diversity in boreal forests. We also assessed whether these effects were dependent on forest attributes (stand type, time since fire, and time since harvest). We retrieved data from seven different studies within 101 sites in boreal forests in Eastern Canada. Our data included forests harvested with two retention patterns: careful logging and clear cut, plus unharvested control forests. Three post-harvest site preparation techniques were applied: plow or disk trenching after careful logging, and prescribed fire after clear cut. We collected trait data (10 traits) representing plant morphology, regeneration strategy, or resource utilization for common species. Our results demonstrated significant variation in functional diversity after harvest. The combined effect of retention pattern and site preparation was the most important factor explaining understory diversity compared to retention pattern only and forest attributes. According to RLQ analysis, harvested forests with site preparation favored traits reflecting resistance or resilience ability after disturbance (clonal guerilla species, geophytes, and species with higher seed weight). Yet harvested forests without site preparation mainly affected understory plant species via their light requirements. Forest attributes did not play significant roles in affecting the relationship between site preparation and functional diversity or traits. Our results indicated the importance of the compounding effects of light variation and soil disturbance in filtering understory diversity and composition in boreal forests. Whether these results are also valid for other ecosystems still needs to be demonstrated.

Multiaged redwood responds well to partial harvest and herbicide treatments

Chemical control of unwanted trees can be a cost-efficient tool for forest management and restoration. In California, United States, the response of merchantable conifers to hardwood control is poorly understood. We studied the tree growth of coast redwood (Sequoia sempervirens (Lamb. ex D. Don) Endl.) following herbicide frill treatment of competing tanoak (Notholithocarpus densiflorus (Hook. & Arn.) Manos, C.H. Cannon, & S. Oh), coinciding with a partial harvest of conifers. The radial growth of 420 redwoods in 45 plots was measured using increment cores. With or without partial harvesting, herbicide treatment of tanoak enhanced growth of most redwoods: 23% of redwoods in herbicide-only plots and 34% of redwoods in herbicide + harvest plots had ≥100% higher posttreatment basal area increment (BAI). In untreated plots, 67% of redwoods displayed declining BAI. The response of redwoods (the ratio of 8-year postharvest BAI to 8-year preharvest BAI) was 59% higher in herbicide-only plots and 108% higher in herbicide + harvest plots compared with untreated control plots over the same period. Redwoods with long crowns maintained rapid growth with or without treatment. Trees growing slowly before treatment exhibited the greatest response, provided that they had relatively long crowns and were not left in suppressed crown positions. Forest managers implementing partial harvesting and (or) chemical control of hardwoods can expect to maintain or promote rapid growth of most residual redwoods.

Forest Understorey Vegetation: Colonization and the Availability and Heterogeneity of Resources

Understorey vegetation comprises a major portion of plant diversity and contributes greatly to nutrient cycling and energy flow. This review examines the mechanisms involved in the response of understorey vegetation to stand development and the overstorey canopy following disturbances. The overall abundance and diversity of the understorey is enhanced with the availability and heterogeneity of light, soil nutrients, soil moisture, and substrates. Vascular plants are positively impacted by the availability and heterogeneity of light and soil nutrients, whereas non-vascular vegetation is more strongly influenced by colonization time, soil moisture, and substrates, and is decreased with a higher proportion of broadleaf overstorey. The availability of resources is a prominent driver toward the abundance and diversity of understorey vegetation, from the stand initiation to stem exclusion stage under a single-species dominated overstorey. However, resource heterogeneity dominates at the later stages of succession under a mixed overstorey. Climate and site conditions modify resource availability and heterogeneity in the understorey layer, but the extent of their influences requires more investigation. Forest management practices (clearcutting and partial harvesting) tend to increase light availability and heterogeneity, which facilitates the abundance and diversity of understorey vascular plants; however, these factors reduce the occurrence of non-vascular plants. Nevertheless, in the landscape context, anthropogenic disturbances homogenize environmental conditions and reduce beta-diversity, as well, the long-term effects of anthropogenic disturbances on understorey vegetation remain unclear, particularly compared with those in primary forests.

Growth and survival dynamics of partially cut northern hardwood stands as affected by precut competition and spatial distribution of residual trees

Abstract Modelling growth and survival dynamics after partial harvesting must take account of the heterogeneous spatial pattern of residual trees that results from the presence of machinery trails. We used data from 23 permanent sample plots in northern hardwood stands to reconstruct the growing environment of individual trees before and after partial harvesting. We modelled harvest probability, growth response and survival probability using a complementary set of explanatory variables that was assembled to reflect the spatial distribution of trees and skid trails prior to and after harvest. Results showed that the distribution of harvested trees was concentrated in skid trails and in their close vicinity. However, this spatial pattern had no significant effect on either the post-cut basal area increment (BAI) or the survival of residual trees. BAI and survival of individual trees were both mostly related to the competitive environment prior to harvest, while post-cut changes in competitive environment had only a marginal effect on growth and survival dynamics. We conclude that selection cuts did not substantially increase the growth and survival of residual trees, likely because tree removal was mostly concentrated near skid trails, where the negative effects of machinery access were highest.

Historical fire in the Appalachian Plateau of Ohio and Kentucky, USA, from remnant yellow pines

BackgroundKnowledge of historical fire regimes informs the restoration of woodland communities. In the Appalachian Plateau of Ohio and Kentucky, USA, little is known about the long-term history of fire in oak–pine communities, which are declining in the region. To address this knowledge gap, two sites with remnant fire-scarred yellow pines, Hatton Ridge in Kentucky and McAtee Run in Ohio, were studied to document aspects of the historical fire regime. Cross-sections from fire-scarred yellow pines were collected. Fire chronologies were constructed and fire intervals were calculated using standard dendrochronological methods.ResultsFires, the great majority of which occurred in the dormant season, were frequent at both sites from circa 1750 at Hatton and 1800 at McAtee, until the suppression period (1930 to present); only one fire was recorded after 1930. Mean fire intervals (MFI) for the entire period were nearly identical, 4.7 and 4.4 years at Hatton and McAtee, respectively. At both sites, MFIs were lowest in the industrial period (1850 to 1930). At Hatton, the MFI was 6.6 years before 1850 and 3.5 years from 1850 to 1930, while at McAtee, the MFI was 8.4 years before 1850 and 2.7 years from 1850 to 1930. At both sites, the occurrence of fire was not more frequent than expected in years associated with a drought. At McAtee, the majority of pine establishment occurred in pulses during two periods, 1770 to 1781 and 1853 to 1867, suggesting stand-scale canopy disturbances; the second pulse was associated with frequent burning. In contrast, large pulses of pine establishment were not found at Hatton.ConclusionsYellow pines were a component of these communities, which experienced frequent fire for at least 130 to 160 years. After more than 70 years with little or no fire, yellow pines are now a minor component of the overstory and pine regeneration is essentially absent. Although intensive management with partial harvesting and frequent fire would be required to restore oak–pine woodlands on appropriate sites, it would serve to sustain these increasingly uncommon communities.

Classifications of Forest Change by Using Bitemporal Airborne Laser Scanner Data

Changes in forest areas have great impact on a range of ecosystem functions, and monitoring forest change across different spatial and temporal resolutions is a central task in forestry. At the spatial scales of municipalities, forest properties and stands, local inventories are carried out periodically to inform forest management, in which airborne laser scanner (ALS) data are often used to estimate forest attributes. As local forest inventories are repeated, the availability of bitemporal field and ALS data is increasing. The aim of this study was to assess the utility of bitemporal ALS data for classification of dominant height change, aboveground biomass change, forest disturbances, and forestry activities. We used data obtained from 558 field plots and four repeated ALS-based forest inventories in southeastern Norway, with temporal resolutions ranging from 11 to 15 years. We applied the k-nearest neighbor method for classification of: (i) increasing versus decreasing dominant height, (ii) increasing versus decreasing aboveground biomass, (iii) undisturbed versus disturbed forest, and (iv) forestry activities, namely untouched, partial harvest, and clearcut. Leave-one-out cross-validation revealed overall accuracies of 96%, 95%, 89%, and 88% across districts for the four change classifications, respectively. Thus, our results demonstrate that various changes in forest structure can be classified with high accuracy at plot level using data from repeated ALS-based forest inventories.

Leaf harvesting severity affects total phenolic and tannin content of fresh and dry leaves of Moringa oleifera Lam. trees growing in Gauteng, South Africa

The most important chemicals common in Moringa oleifera Lam. leaves are polyphenols and tannins. They are synthesised during development and the amount and composition are primarily dependent on environmental conditions and factors such as leaf harvesting. Trials were conducted in the Gauteng Province at the University of Pretoria Experimental Farm on Hillcrest Campus (250 45′ 08.6″S, 280 15′ 30.S" E), with an altitude of 1372 m above sea level and an average annual rainfall of 640 mm. Five year old M. oleifera tree orchard were used for this study and treatments were laid in a randomised complete block design, where 12 plants were used in each plot within a row, with a plant spacing of 2 × 2 m2. Partial harvesting was done at 25% leaf removal, while severe leaf harvesting was done at 75% leaf removal. The control trees were not harvested, but only leaf (mature and immature) samples were harvested for analyses. Leaf samples from all plots were harvested in September, November, February and May in years 1 and 2. Leaf samples (equal quantities of immature and mature leaves) from partially, severely harvested and control plots were harvested and separated into batches, one to be analysed as fresh material and the other as dry material. The dry material was placed in paper bags and allowed to immediately air dry under normal room conditions of 26 °C. Partially harvested M. oleifera leaves produced an increased accumulation of total phenolic content (TPC) 35–44 g/kg dry weight, from spring to summer season, in comparison to severe harvesting 26–35 g/kg dry weight. With severe leaf harvesting (75%), because of probable lower photosynthetic capacity, phenols across September to May of years 1 and 2 decreased. The onset of low temperatures in May resulted mostly higher TPC and tannin build up, which means that cold stress may improve more bio-active compounds in the leaves. Dark and fully developed mature leaves mainly contained the highest amount of TPC. Moringa oleifera leaves collected and dried at each harvesting interval, instead of freshly milled, do show the same quantity of TPC and tannins across the season illustrating that air drying can be used as a post-harvest handling technique, extending shelf life without losses of vital phenols. With harvesting severity as a concern in Moringa, this study confirms that the TPC and tannins in mature and immature leaves did not rise to toxic levels for human consumption.

Understory vascular plant responses to retention harvesting with and without prescribed fire

Wildfire is the predominant natural disturbance in the boreal forests of western Canada. Natural disturbance based forest management involves the use of retention harvesting to retain stand structural diversity after harvest; however, unlike fire, this partial harvesting technique does not cause combustion of the forest floor. Application of prescribed burning to areas treated with retention harvesting might emulate the influence of wildfires more effectively than harvesting alone. We compared understory vascular plant diversity, abundance, and composition between forest stands subjected to dispersed retention harvesting (10% retention) with and without prescribed burning 1, 6, and 11 or 12 years after burning. Untreated forest was included as a reference. Research was conducted in conifer-dominated, mixedwood, and deciduous-dominated boreal forest stands in northwestern Alberta, Canada. In deciduous-dominated stands, burned areas of retention harvested stands had higher species richness and greater cover than did unburned areas. In all three forest cover types, effects of harvest with and without burn on species richness, cover, and composition were still evident a decade after disturbance. Fire-adapted species benefited most from the prescribed burn treatment. The combination of prescribed burning with retention harvesting can be considered a useful option in forest management that aims to emulate natural disturbance.

The long-term case for partial-cutting over clear-cutting in the southern Appalachians USA

Prior to the 1950s, common partial harvesting operations in the southern Appalachians USA involved the removal of logs by ground-skidding and the construction of steep access roads and skid trails along stream channels. Little is known about how these historical practices affected long-term vegetation changes. An experimental watershed in the Coweeta Hydrologic Laboratory was partially harvested in the years 1942–1952 according to these exploitive practices. We compared the partial-cut watershed to a clear-cut watershed and an untreated, reference watershed. Using long-term vegetation surveys, we analyzed patterns in aboveground biomass accumulation, species composition and diversity (Shannon’s index Hʹ and species richness) among watersheds. Contrary to our expectations, the partial-cut watershed recovered to reference levels of aboveground biomass and their species composition was similar over time. The clear-cut watershed had greater abundance of tulip poplar (Liriodendron tulipifera) and black locust (Robinia pseudoacacia) than the other two watersheds. The partial-cut watershed increased in diversity over time, but it remained less diverse than the reference watershed; whereas, the clear-cut watershed had lower diversity than the other two watersheds, and its diversity did not change over time. Distributions of functional groups based on water use and nutrient acquisition traits, and shade tolerance were similar between the partial-cut and the reference watersheds, but differed from the clear-cut watershed. By the 2010s, partial-cut and reference watersheds had similar proportions of diffuse-porous (32% and 33%) and ring-porous (48% and 42%) basal area, while the clear-cut watershed had more diffuse-porous (43%) and less ring-porous (36%) species than the partial-cut or reference watersheds. Tree species associated with arbuscular mycorrhiza were more abundant in the clear-cut watershed than the partial-cut or reference watersheds. Overall, the partial-cut watershed, even with the extreme soil disturbance, did not alter long-term species composition and diversity as dramatically as the clear-cut watershed. These results could help forest managers, conservationists, and hydrologists understand the long-term effects of partial-cutting versus clear-cutting.

Stem- and stand-level growth and mortality following partial cutting in eastern boreal poplar – white spruce stands

Variable retention (VR) and partial cutting are both considered important silvicultural tools of natural disturbance or ecosystem based forest management approaches. Partial harvesting differs from VR in that post-treatment growth responses and stand regeneration are the primary objective rather than the maintenance of biodiversity. This partial cutting study is undertaken in mixed poplar (Populus spp.) – white spruce (Picea glauca (Moench) Voss) stands in the eastern Canadian boreal mixedwood forest. It compares, at the tree level, absolute growth rates (AGR) and relative growth rates (RGR) of basal area (BA) and stem survival; and at the stand level, it also compares absolute BA growth, mortality, and sapling density 10 years following treatment. The completely randomized experiment was established with four intensities of partial cutting (0, 50%, 65%, and 100% of poplar BA). All partial cutting intensities had a significant and similar positive effect on AGR of residual spruce stems. Complete poplar removal resulted not only in the highest increase in RGR of suppressed and intermediate spruce stems, but also in higher spruce mortality. Removal of 50% of the initial poplar stand BA provided the best trade-off between positive residual stem growth of spruce and poplar and limited post-treatment mortality.

Effects of disturbance and site factors on sapling dynamics and species diversity in northern hardwood stands

The northern hardwoods forest ecosystem of eastern North America provides a wealth of products and services to human society. These forests have been managed under partial harvesting treatments to meet wood production objectives of desired species while maintaining or increasing structural and compositional heterogeneity. Few studies have examined how disturbance and site factors interactions may influence sapling dynamics and species diversity in northern hardwood forests. We used a retrospective approach to examine the impacts of disturbance and site factors on sapling (trees > 130 cm in height and <10.0 cm dbh) dynamics and species diversity across 37 stands with time since harvest ranging from 6 to 20 years. We assessed American beech (Fagus grandifolia Ehrh), sugar maple (Acer saccharum Marsh.), red maple (Acer rubrum L.) and yellow birch (Betula alleghaniensis Britt.) saplings density as functions of disturbance intensity (% basal area cut and overstory tree mortality rate (%)) and site factors. We also examined the effects of disturbance, site factors and relative density of American beech, red maple, sugar maple and yellow birch saplings on species diversity at the sapling layer. The density of American beech saplings decreased significantly with harvest intensity. High harvest intensity significantly reduced American beech sapling density at high depth-to-water sites. However, the densities of red maple and yellow birch saplings increased significantly with increasing harvest intensity. We found that high harvest intensities had less negative effect on sugar maple sapling density compared with American beech. Our results also showed that tree species diversity (Shannon diversity index (H′)) increased with harvest intensity up to about 75% and then declined. However, depth-to-water (DTW) significantly changed the magnitude of tree species diversity response to harvest intensity. Red maple appeared to have contributed more to species diversity than the other hardwood tree species. Given that sugar maple sapling density was generally higher than American beech at high harvest intensities in this study, management regimes that promote mid-tolerant species in American beech-presence stands may eventually benefit sugar maple more than American beech in these forest types. These strategies may also increase species diversity and improve forest ecosystems functions and services.

Evaluation of minor carps intercropping in carp polyculture vis‐à‐vis other grow‐out cropping patterns of carp farming

One year grow-out evaluation of four cropping patterns of carps, viz. control: single stock single harvest (SSSH); T-1:intercrop of minor carps and Indian major carps (IMC); T-2:single stock multiple harvests (SSMH); and T-3:multiple stock multiple harvests (MSMH) was conducted in eight earthen ponds (0.09 ha each). Ponds were stocked with three IMCs (catla, rohu and mrigal) at 1:1:1 ratio at 10,000 fingerlings/ha combined density. T-1 was additionally stocked with 10,000 fingerlings/ha of minor carps (Puntius gonionotus, Labeo fimbriatus and Puntius sarana), while T-2 with additional 10,000 fingerlings/ha of the IMC. Periodic removal of partial biomass ensured prevalence of better water quality in treatments (higher water pH, higher dissolved oxygen and reduced inorganic nutrients). It helped to improve fish growth as average harvested weight of rohu and mrigal remained similar in treatments despite the presence of greater inter- and intraspecific competitions in intercrop and SSMH, respectively, and periodic stocking of younger juveniles in MSMH. Catla showed significantly higher growth in MSMH. The biomass yield in intercrop, SSMH and MSMH were 21%, 17% and 24% higher than SSSH, but the respective net incomes were 32.9, 21.3 and 56.5% higher. Partial harvest also helped reducing FCR in the order T-3<T-2<T-1<control. While the study showed MSMH as the most productive cropping pattern for biomass yield, the intercrop of minor carps and IMCs proved to be the most water productive (gross and consumptive water use) cropping method to produce varied fish protein with higher biomass yield.

Green-tree retention and relative habitat use by mule deer (Odocoileus hemionus) 20 years after harvest of Douglas-fir (Pseudotsuga menziesii) – Lodgepole pine (Pinus contorta) forest

Mule deer (Odocoileus hemionus) are a major mammal species in many interior Douglas-fir (Pseudotsuga menziesii) forest ecosystems in western North America. During winter in areas of relatively high snowpacks, mule deer seem to require older trees with large crowns for snow interception, but these forests are often targeted for harvest. Green-tree retention (GTR) may offer a solution to this conundrum. We tested three hypotheses (H) that, at 20–22 years after harvest, (H1) abundance (e.g., basal area and density of residual trees and understory stand structure) of conifers, (H2) abundance, species richness, and diversity of understory vegetation, and (H3) relative habitat use by mule deer, will decline with lower levels of tree retention. Fecal pellet-groups of deer were counted in summer and winter periods for three years in replicated stands of dispersed retention, aggregated retention, patch-cut, group selection, and uncut forest in mixed Douglas-fir - lodgepole pine (Pinus contorta) forest in southern British Columbia, Canada.Mean basal area, density, and canopy closure of overstory Douglas-fir trees were generally greater in the patch-cut, group selection, and uncut forest sites than dispersed and aggregated retention sites, and hence supported the overstory part of H1. Mean density of understory conifers did not support H1 as the majority of these trees were in the dispersed and aggregated retention stands. There was no difference in mean abundance nor species richness of understory vegetation among treatment sites. Mean species diversity tended to be 1.4–1.8 times higher in the patch-cut and group selection than the other sites, and hence provided weak support for H2. Patch-cut and group selection sites were dominated by Douglas-fir trees in both the overstory and understory, along with potential forage shrub species, and were used by deer more than the dispersed and aggregated retention stands in both summer and winter. Relative habitat use by deer in uncut forest was greater than the retention stands and generally similar to the patch-cut and group selection sites in both seasons. These results suggest that partial harvesting of these mixed Douglas-fir – lodgepole pine stands across a range of opening sizes (e.g., 0.1 to 2–5 ha) should provide suitable habitat for mule deer over time.

Impacts of silvicultural prescriptions and implementation of best management practices on timber harvesting costs

ABSTRACTRising costs of forest operations and decreasing revenue generated from harvesting are becoming critical challenges in forest management throughout the Northeastern US. Along with this, the low markets for comminuted forest residues and stricter policies on environmental protection have prompted utilization of these materials as slash mats on skid trails for minimizing soil disturbances. The aim of this study was to evaluate the cost of different silvicultural treatments and utilization of forest residues generated from a mechanized timber harvesting operation for implementing Best Management Practices (BMPs). The field-based experiment was done in central Maine, where four forest stands were managed at varying intensities following silvicultural prescriptions common to the region (partial harvest (PH) and clear-cut (CC) treatments). Variables measured included delay-free cycle times of various timber harvesting machines, predictor variables, and stand features. The total cost of PH was higher than that of CC ($22.94 m−3 versus $14.88 m−3). Of the various operational phases, the costs associated with skidding was the highest and ranged from 52 to 70% of the total cost for PH and CC, respectively. The cost of BMP implementation was estimated to be between $10 and $52 PMH−1 or $1.0 and $3.7 m−3, and was influenced by several factors, including machine maneuverability and the extent of area which demanded BMP implementation. This information on the cost and productivity for timber harvesting operations, along with BMP implementation, will support the development of economic and environmentally sustainable harvesting strategies.

Management Implications of Using Brush Mats for Soil Protection on Machine Operating Trails during Mechanized Cut-to-Length Forest Operations

Mechanized cut-to-length forest operations often rely on the use of brush mats created from harvesting debris (tree limbs, tops, and foliage) to reduce soil disturbances as a result of in-stand machine traffic. These brush mats, placed directly on the forest floor within machine operating trails, distribute loads of timber harvesting and extraction machinery to a greater area, thereby reducing peak pressures exerted to the ground and rutting for maintaining technical trafficability of operating trails. Forest biomass has also been promoted as a source of green and renewable energy, to reduce carbon emissions from energy production. However, to maintain sufficient quality of biomass for bioenergy operations (high heating value and low ash content), brush needs to be free of contaminants such as mineral soil. This constraint eliminates the possibility of the dual use of brush, first as a soil protective layer on machine operating trails and afterwards for bioenergy generation. Leaving machine operating trails uncovered will cause machine loads to be fully and directly applied to the soil, thus increasing the likelihood of severe soil disturbance, tree growth impediment and reducing trail trafficability. The main objective of this study was to quantify the effect of varying machine operating trail spacing and width on the amount of brush required for soil protection. This was achieved by creating five model forest stands (four mature and one immature), commonly found in New Brunswick, Canada, and using their characteristics as input in the Biomass Opportunity and Supply Model (BiOS) from FPInnovations. BiOS provided several key biomass related outputs allowing the determination of the amount of biomass available for soil protection, which was the main focus of this research. The simulation results showed that regardless of trail area tested, all four mature forest stands were able to support uniform distribution of 20 kg m−2 brush mats (green mass) throughout their entire trail network during clear-cut operations but not during partial harvests. From the three factors assessed (brush amount, trail width, and trail spacing), trail width had the highest effect on the required brush amount for trail protection, which in turn has a direct impact on the amount of brush that could be used for bioenergy generation.

Changes in forest structure along a chronosequence in the black spruce boreal forest: Identifying structures to be reproduced through silvicultural practices

In managed boreal forests, partial harvesting has been proposed to promote forest structural complexity and to therefore maintain associated biodiversity. However, there have been few studies identifying forest structures that should be maintained within the forest matrix, and fewer still on changes in these structures during succession. Consequently, there is no tool to identify these different structures in the field or their sequence along natural succession. This study proposes a key that can be used in the field and allows for the identification of different forest diameter structures along a successional sequence in the black spruce boreal forest. The specific objectives of this study were (1) to classify the types of forest structures encountered in natural black spruce boreal forest based on their diameter distribution, and (2) to link this classification to time since last fire and its spatial homogeneity at the stand level. This study shows that the forest stand structure, in black spruce forests, is varied and that this structural variety is mainly controlled by time since last fire. It also shows that the timing of stand structural maturation varies with severity of the last fire and surficial deposit. The identification key suggests that based on tree diameter distribution it is possible to discriminate among young, mature and old forest structures, which could help forest managers select stands to be harvested according to different objectives and hence maintain the variety of black spruce forest structures at the landscape scale.