Harvest Treatments Research Articles

Analysing How Pre-Fire Habitat Legacy and Post-Fire Management Influence the Resilience of Reptiles to Fire

At the landscape scale, the Mediterranean region is a mosaic of habitats occupied by plants and animals with different resilience to fire. One of these habitats, the pine plantation, is characterized by its structural simplification and susceptibility to fire. Despite its high flammability, few studies have compared the response of animal communities between pine plantations and other autochthonous woodlands. For five years after a large fire in southwestern Europe, we surveyed reptiles in two natural habitats (oak forest, scrubland) and a pine plantation managed with salvage logging, a post-fire practice which consists of the complete harvesting and removal of death burnt trees. Reptile abundance and species composition were examined to assess differences in the reptile community between these habitats. Differences between burnt and unburnt transects were limited to the first year after the fire, while, over the entire five-year period, differences in species composition and abundance were due to vegetation type instead of fire. The pine logged area showed a delay in the recovery of vegetation and also in the appearance of many reptile species after the fire. At the reptile species level, we found evidence of both positive responses to fire (for lizards with high heliothermic activity) and negative ones (for specialist snake species). Overall, our results confirm the resilience of the reptile community to fire. The mosaic of habitats in the Mediterranean region and the openness caused by fire can increase the reptile biodiversity (landscape- plus pyro-diversity effects), but some practices such as salvage logging coupled with fire regime shifts (larger and more frequent fires) can compromise the conservation of the biodiversity in fire-prone regions.

Effects of deforestation and afforestation on water availability for dry bean production in Haiti

Haitian watersheds suffer from a lack of environmental management and the absence of conservation practices, which impairs natural resources and agricultural productivity. This is aggravated by harvesting trees to compensate for reduced crop production and income. Deforestation can further deteriorate the natural and agricultural systems by increasing the temporal variability of water availability, often realized in the forms of floods and droughts. The goal of this study was to determine the effects of both deforestation and afforestation on water resources and agricultural productivity. We selected the Courjolle River watershed and its downstream irrigation districts because they represent the linkage between the upstream forest and downstream agricultural areas. Watershed hydrology and dry bean growth were simulated with the Soil and Water Assessment Tool (SWAT) model and the CSM-CROPGRO–Dry bean model of the Decision Support System for Agrotechnology Transfer (DSSAT). The parameters for both models were calibrated to streamflow and dry bean growth measurements that were made in the study areas. Deforestation and afforestation scenarios were developed based on an understanding of the local landscape. The modeling experiment showed that deforestation could decrease water availability and stability, causing a decrease in dry bean production, while afforestation had the opposite effect. An increase of the afforested areas from 25% to 100% of the watershed increased the streamflow by 2–7%, compared to the current land cover, during dry periods. On the other hand, an increase in deforested areas decreased the amount of available water for downstream agricultural areas by 6–24%. Potential changes in the water availability due to the land cover changes then affected the yield of dry bean grown in the downstream irrigation areas, from −42–24% under the deforestation and afforestation scenarios. The study demonstrated how improved hydrologic stability due to an increase in tree cover could promote agricultural production. It also showed that afforestation could be an effective way to manage both the natural and agricultural resources in Haiti, improving the environmental sustainability of the watershed and the economic sustainability of local smallholder farmers.

Effects of biotic and abiotic drivers on the growth rates of individual trees in temperate natural forests

Understanding the driving factors for individual tree growth is of great significance to devise effective forest management strategies. Such information can be used to select appropriate tree harvesting times, and to provide valuable guidance for creating suitable local environmental conditions during the period of tree growth. However, currently it remains unclear how biotic and abiotic factors affect individual tree growth on large geographical scales. In the present study, based on a dataset from 457 field plots and the growth records of 7,560 individual trees in natural forests in northeastern China, the effects of tree size, local environmental conditions, and regional climate characteristics on the 5-year basal area increment (BAI) of the three dominant species (Quercus mongolica, Betula platyphylla, and Larix gmelinii) were investigated using nonlinear mixed-effects models. Although the magnitude and direction of the drivers’ effects on the BAI differed among the three species, the following variables explained major proportions of the variation (conditional R2 ranging from 0.57 to 0.66) in the BAI: 1) Diameter at breast height; 2) Mean temperature and precipitation during the growing seasons; and 3) Species mingling and the basal areas of larger trees. In addition, an interactive effect between temperature and precipitation was significant for Q. mongolica. On the basis of our results, we identified the most important variables among multiple drivers affecting the growth of individual trees, and developed individual tree growth models for the three species. Our results provide an initial basis for the future scientific management of some of the most important natural forest regions in the world.

Silvicultural Management System Applied to Logged Forests in the Brazilian Amazon: A Case Study of Adaptation of Techniques to Increase the Yield and Diversity of Species Forestry

The existence of degraded forests is common in the Eastern Amazon. The maintenance of these forests standing and the recovery of their productivity play an important role in the conservation of biodiversity, storage and carbon sequestration. However, the management techniques currently employed are designed for natural forests in the first harvest cycle or lightly explored and do not apply adequately to forests that have gone through several harvest cycles. Therefore, adaptations and the establishment of new management criteria that take into account other characteristics of these types of forests are necessary to ensure their sustainability. The objective of this study was to propose a silvicultural management system that has the potential to recover and perpetuate the productivity of an intensively logged tropical forest. A forest census was carried out on 535.6 ha for trees with dbh ≥ 25 cm. With these data, the following two treatments were designed: (1) criteria: the BDq method was applied from B = 9.8 m2 ha−1, D = 100 cm and q = 2. The criteria for standing wood commercialization were, in this order, first, Health; second, Tree Stem; third, Tree Density and fourth, dbh ≥ 105 cm. (2) Control: the planning was in accordance with Brazilian regulations. For the cost–benefit and sensitivity analysis, the Net Present Value (NPV) was used and a projection of ±20% was made in the commercial price of standing wood. In the criteria treatment, a higher number of trees and species destined for the commercialization of standing wood was verified in relation to the control treatment, showing a greater diversity of species. In the criteria treatment, NPV was positive and superior to the control treatment in all scenarios. The proposed silvicultural management system with an object of an explored and enriched forest, with criteria for harvesting trees with a minimum cut diameter of 25 cm, proved to be viable to generate economic returns and with conservationist potential for the continuous supply of forest products and maintaining biodiversity.

Effect of Different Levels of Borax and Gypsum on Soil Chemical Properties and Yield of Finger Millet (Eleusine corocana L) in Southern Dry Zone of Karnataka

A field experiment was carried out in Kharif 2016 on B-deficient sandy loam soil at College of Agriculture, VC Farm, Mandya to study the effect of graded levels borax (5, 10, 15 and 20 kg ha1) and gypsum (100 and 200 kg ha-1) on yield and soil chemical properties of irrigated finger millet (Eleusine corocana L.) in Southern Dry Zone of Karnataka. A significantly higher grain yield of 45.95 q ha-1 (17.56% higher than the control) and a B:C ratio of 3.06 were also recorded at T12 compared with RDF + FYM (T1). Due to application of borax and gypsum, the pH, EC, and organic carbon content in soil during flowering stage and at crop harvest were non-significant. However, at the flowering and harvest of the crop, the T4 treatment had the lowest pH (7.49 and 7.43, respectively), whereas the T12 (flowering stage) and T10 (after harvest) treatments had the highest pH (7.65 and 7.67, respectively). Higher soil NPK values were detected in all treatments at flowering stage compared to after the crop was harvested. Application of borax 10kg ha-1 + 100 kg gypsum ha-1 along with RDF and FYM had a significantly higher exchangeable calcium content after harvest (6.77 cmol kg-1) than T1 (5.23 cmol kg-1). Sulphur content in soil at flowering stage and after harvest of crop was found to be significant among the treatments due to application of different levels of gypsum. High levels of borax applied treatments, i. e. T5 (T1+20 kg borax ha-1) and T15 (T5 + 200 kg gypsum ha-1) recorded significantly higher content of B at flowering stage (4.18 and 4.09 mg kg-1, respectively) and at harvest of crop (3.88 and 3.68 mg kg-1, respectively) when compared to T1 (1.32 and 1.16 mg kg-1, respectively). Therefore finger millet absorption of boron may be reduced by using borax with a greater dosage of gypsum (200 kg ha-1). As a result, optimising the Ca/B ratio in the soil and plant is critical for increasing irrigated finger millet yields.

Oomycetes associated with Prunus serotina persist in soil after tree harvest

Soil-borne pathogens can shape forest communities by lowering seedling survivorship. Many soil pathogens can persist long-term as survival spores, but how long pathogens outlive tree hosts in gap soils and whether they continue to affect seedling survival is uncertain. We studied the presence of oomycetes and evaluated seedling performance in soils near live Prunus serotina trees, and 0.5 and 1.5-y-old stumps. We isolated five species of oomycetes from soils, two of which were pathogenic (Pythium intermedium and Pythium irregulare) to Prunus serotina. There was a non-significant ~10.5% increase in conspecific seedling survival in stumps versus live trees, and pathogens were present in soils of all stump ages. The continued presence of pathogens of Prunus serotina in gap soils demonstrates the potential for impacts on conspecific regeneration after tree death, though the slight improvement in survival suggests that these effects may weaken with time.

Three-dimensional modeling of photo fermentative biohydrogen generation in a microbioreactor

Photo fermentation is an emerging approach of biohydrogen production as it is energy saving and environmentally friendly. Understanding mechanisms of controlling the bacteria growth and biohydrogen production is critical for effective improvements in energy harvest and waste treatment in photo fermentative bioreactors. In this study a comprehensive three-dimensional numerical platform of photo fermentation was developed, based on lattice Boltzmann method coupled with cellular automata. The model accounts for photosynthetic bacteria growth, illumination energy conversion by photosynthetic bacteria, and light transfer under biofilm growth. The results showed a threshold of illumination intensity. Below this threshold, the bioreactor performance increased as the illumination intensity increased. Above the threshold, the performance declined if the illumination intensity rose. The normalized average biohydrogen production at the illumination intensity of 6000lx, increased about 66.31%, 13.82% and 13.12%, respectively, compared to ones at 4000lx, 5000lx and 7000lx. An increase in inlet glucose concentration could increase biohydrogen concentration and extraction but dwindled biohydrogen yield. It was found that a lower inlet velocity had higher biohydrogen production rate and concentration but lower biohydrogen extraction and yield. The results demonstrate that the present LBM-CA platform can be a tool to study and enhance the photo fermentative production of biohydrogen.

Nitrogen use efficiency, partitioning, and storage in cool climate potted Pinot Noir vines

Optimal timing of nitrogen (N) fertilizer to promote N use efficiency (NUE) in cool climate wine regions is largely unknown. One year-old potted Vitis vinifera L. (Vitaceae) cv. Pinot Noir vines were subjected to soil applied 15N-labelled calcium nitrate (5.5 atom%) fertilizer at four application timings (budbreak to fruit set, fruit set to veraison, veraison to harvest, or spread evenly across the growing season) over two growing seasons (2017/18 and 2018/19) at a rate of 12 g N vine−1. Annual vine parts (leaves and clusters) were collected at commercial harvest in both 2018 and 2019 and the remaining vine was destructively harvested during winter dormancy. Vines were separated into organs (leaves, clusters, shoot, trunk, and roots) and organ dry matter was determined before samples were ground into a fine powder to determine total N percentage and 15N atom percentage using flash combustion isotope ratio mass spectrometry (varioPYRO cube coupled to Isoprime100 mass spectrometer). Compared to the average values obtained from the other treatments, the veraison to harvest treatment significantly reduced whole vine dry matter by 39.1% and vine NUE by 42.1%. Yield was also reduced by 12.9% compared to the budbreak to fruit set treatment. NDF, defined here as the proportion of N within the vine (or vine organ) that was derived from fertilizer N, and overall vine total N content was lower in the veraison to harvest treatment due to the reduction of root and shoot NDF content. This suggests that for young, actively growing vines in cool climates, limiting N applications until veraison is inefficient and ineffective. No significant differences in NUE, N partitioning or N storage were observed between the other fertilizer N application timings.

Inter-Temporal Aggregation for Spatially Explicit Optimal Harvest Scheduling under Area Restrictions

Abstract We propose a new approach to solve inter-temporal unit aggregation issues under maximum opening size requirements using two models. The first model is based on Model I formulation with static harvest treatments for harvest activities. This model identifies periodic harvest activities using a set of constraints for inter-temporal aggregation. The second model is based on Model II formulation, which uses dynamic harvest treatments and incorporates periodic harvest activities directly into the model formulation. The proposed approach contributes to the literature on spatially constrained harvest scheduling problems as it allows a pattern of unit aggregation to change across multiple harvests over time, as inter-temporal aggregation under a maximum opening size requirement over period-specific duration. The main idea of the proposed approach for inter-temporal aggregation is to use a multiple layer scheme for a set of spatial constraints, which is adapted from a maximum flow specification in a spatial forest unit network and a sequential triangle connection to create fully connected feasible clusters. By dividing the planning horizon into period-specific durations for different spatial aggregation patterns, the models can complete inter-temporal spatial aggregation over the planning horizon under a maximum opening size requirement per duration.

Forest management effects on the ectomycorrhizal macromycete community in tropical montane forests in Mexico

While forest management impacts the ectomycorrhizal fungi (EMF) community, most of the evidence regarding such effects has been obtained from temperate forests of the Northern Hemisphere and little is known of their prevalence in highly diverse tropical habitats. This study analyzes the responses of the EMF community in managed tropical montane forests in the southern Mexican state of Chiapas. EMF community composition and diversity were evaluated over a 2-year period along a gradient of structural and microclimatic conditions of the forest associated with the stages of a cycle of silvicultural practices (R = release cutting, T = thinning, and F = final regeneration cutting), as well as in a mid-successional unmanaged forest (UF) as a reference system. The silvicultural practices involve varying intensities of tree harvesting (≈ 20% in T to ≈ 80% in F). It is hypothesized that: (1) diversity and composition of EMF communities are influenced by changes in forest conditions, principally as a result of canopy cover alteration due to forest management, and (2) late forest successional conditions are associated to more diverse EMF communities, while more intensive silvicultural practices reduce their diversity. A total of 75 EMF species were recorded. Diversity analysis using Hill numbers showed a close relationship between diversity and forest conditions: total species richness, 0D = 5.7 ± 0.6 in F up to 11.7 ± 1.3 in UF; richness of abundant species, 1D = 4.1 ± 0.4 in F up to 7.5 ± 0.4 in UF; richness of very abundant species 2D = 3.3 ± 0.3 in R up to 5.5 ± 0.3 in UF. Canopy cover (9.8 ± 4% in F and 80.6 ± 5% in UF) was the main factor affecting EMF diversity, mainly due to its influence on herbaceous cover, tree species richness (path analysis, R2 = 0.32; p < 0.05), and microclimatic variables. Turnover of the most abundant EMF species from the most intensive management practice towards the later successional forest conditions was observed. Late successional conditions allow for maintenance of more diverse EMF communities, while more intensive practices reduce their diversity (p < 0.05, in both cases). Rare fungal species appear to be more vulnerable to highly intensive management, and account for most of the EMF diversity in UF. The results indicate the importance of preserving relatively undisturbed species-rich forest stands near intensively managed stands in order to maintain biological integrity of the EMF community and ecosystem functioning in tropical montane forests.

Tree Species Composition, Richness and Diversity in the Northern Guinea-Savanna Taraba State, Nigeria

The study investigated tree species composition, diversity and abundance in the Guinea savanna ecosystem, Taraba State, Nigeria. Three transects with a distance of 500 m apart were used for the study. Four sample plots of 25 m x 25 m size were laid in alternate positions along each transect at 250 m intervals. Identification of trees/shrubs was carried out in the forest reserves. Biodiversity indices such as; Shannon-Wiener diversity index, Species evenness, Simpson’s diversity index, Margalef’s richness index and Menhinick’s diversity index, were estimated at the end of the study. The result of floristic diversity assessment showed that the two forest reserves were able to conserve trees/shrubs species diversity. This was reflected by the value obtained for diversity indices for the two land use types: Shannon- Weinner (3.29, 3.08), species evenness (0.47, 0.49), Simpson (0.95, 0.93), Margalef (6.83, 6.49), Minhinck’s index (2.09, 1.79) for Sonkpa and Jabwanje forest reserves respectively. The density of fruit trees/shrubs encountered in the two forest reserves were (279, 414) which accounted for (47% and 56%) of the total woody population in Sonkpa and Jabwanje forest reserves respectively. Among the prominent fruit trees/shrubs encountered were Nauclea latifolia, Gardenia aqualla, Annona senegalensis, Prosopis africana, Vitellaria paradoxa, Vitex doniana, Strychnos innocua. However, the absence of Irvingia gabonensis and lower density of Afzelia africana was an indication that some important species are already going to extinction while others are endangered. Hence, the State government should, intensify the management of savanna forest by controlling the intensity of tree harvesting, stop illegal felling and encourage enrichment planting. Genetic improvement through germplasm collection and propagation studies should be carried out on the under exploited edible fruit species for genetically improved cultivars production.

Optimizing stand density for climate-smart forestry: A way forward towards resilient forests with enhanced carbon storage under extreme climate events

As a response to the increased pressure of global climate change on most ecosystems, national and international agreements aim at creating forests that are productive, resilient to climate change, and that store carbon to mitigate global warming. However, these aims are being challenged by increased tree mortality rates and decreased tree growth rates in response to increased incidence of extreme drought events. These phenomena make us aware of a lack of crucial insights into the effects of forest management on the growth and survival of trees, and on carbon storage in both trees and forest soils under increased incidence of drought. Here we compile current knowledge on how forest management and drought impact on tree growth and survival, and above- and belowground carbon storage in forest ecosystems. Based on this, we propose that climate-smart forestry may benefit from controlling stand density at intermediate levels (>60%, e.g.~80%) by applying low levels of tree harvest intensity on a regular base. Furthermore, we propose that the actual optimal density will depend on the tree species, site conditions and management history. As a next step, studies are needed that take an above- and belowground approach and combine forest experiments with mechanistic models on water, carbon and nutrient flows in trees and soils within forests in order to transform current results, which focus on either soil or trees and are often highly-context dependent, to a more generic forest framework. Such a generic framework would be needed to enhance understanding across forest ecosystems on how forest management may promote forest resilience, productivity and carbon storage with increasing drought.

Current Status and Recent Stand Structure Dynamics in Mixed Silver Fir—European Beech Forests in Croatian Dinarides: Are There Differences between Managed and Unmanaged Forests?

The environmental, social and economic potential of Dinaric uneven-aged forests along with the complex stand dynamics influenced by different long-term management approaches and environmental factors require comprehensive forest monitoring. This study aimed to explore differences in the current status and recent past dynamics of stand structures between unmanaged and managed mixed fir-beech forests in the Croatian part of the Dinaric Alps using large-scale data from an established monitoring system. From the 74 permanent sample plots distributed within the forest type measured in 2008 and re-measured in 2019, we stratified four strata (types of management regimes): (1) forests out of regular management and tree harvest for at least 30 years, (2) managed state forests on carbonate bedrock, (3) managed state forests on non-carbonate bedrock and (4) managed private forests. In each sample plot, 34 structural attributes were computed to assess indicators of their current status and recent past dynamics of stands in the studied forests. An increasing Q shape diameter distribution with a high number of large and very large trees characterize unmanaged forests and managed forests on non-carbonate bedrock. In managed state forests and private forests, variable (rotated sigmoid) and constant (negative exponential) results were obtained, respectively. Principal component analysis (PCA) distinguished managed and unmanaged forests with decreasing harvest volume and recruitment, increasing basal area, number of very large trees, average diameter at breast height (DBH), crown defoliation of firs and basal area of died beech trees. The current structure, recent and expected stand dynamics in the unmanaged forests (accumulation of standing volume, increase of large diameter trees and large snags, large share of beech, large mean DBH) can be recognized as old-growth attributes. The differences between the studied forest types, potential of both unmanaged and state managed fir-beech forests and approaches to sustain multifunctional forest management in the Dinaric region were discussed.

Effect of Feller-Buncher Model, Slope Class and Cutting Area on the Productivity and Costs of Whole Tree Harvesting in Brazilian Eucalyptus Stands

The operational productivity and costs of tree felling operations can be influenced by several factors, among which, the machine characteristics, slope class, the cutting area and the individual volume of the trees stand out. Thus, the main objective of the present study was to analyze the productivity and production cost for two feller-bunchers with different technical characteristics operating in a eucalyptus forest. The productivity was calculated from a time study and the factors analyzed were two feller-buncher models, two slope classes, and two cutting areas. The machine cost per scheduled hour was based on the methodology of the Food and Agriculture Organization of the United Nations. Analysis of the results showed that the felling and turn operational elements occupied the most time in the operational cycle of feller-bunchers. The machine cost per scheduled hour was USD 69.69 h−1 for feller-buncher 1 and USD 102.03 h−1 for feller-buncher 2. In conclusion, the distinct technical characteristics of feller-bunchers were found to influence the productivity and, consequently, the cost, of the felling operation during the harvesting of whole eucalyptus trees.

Impact of post harvest treatment on antioxidant activity and phenolic profile of Moringa oleifera lam leaves

Moringa oleifera leaves are an important source of dietary phytochemicals, such as flavonoids with high antioxidant activity (AOA). These components are however influenced by the post-harvest treatments applied as well as the processing conditions. Hence, it is crucial to determine the most appropriate post-harvest treatment that preserves or enhances AOA. To this effect the influence of steam blanching, fermentation / oxidation, oven drying and roasting of fresh Moringa leaves on their AOA was investigated. Processing conditions of time and temperature for each treatment were optimised using response surface methodology. The effect of the different treatments at optimal conditions on phenolic profile and AOA were compared. Roasting achieved the most significant (p < 0.05) improvement in phenolics (43%) and AOA (22–31%), which was accompanied by the formation of 2 new compounds, quercetin-3-O-acetylglucoside and Quercetine-3-O-rhamnoside. Steam blanching had the most deleterious effect on phenolics (− 31%) and AOA. Post-harvest treatments qualitatively and quantitatively affect phytochemical profile of Moringa leaves.Graphical abstract

Elemental analysis of mango ripened by different postharvest treatments using laser induced breakdown spectroscopic

Laser induced breakdown spectroscopy (LIBS) provides sample information on elemental scale. Current result depicts both qualitative and quantitative detection of most prominent organic elements like hydrogen (H), nitrogen (N), oxygen (O) and carbon (C) from mango pulp ripened under different post- harvest treatments. Similarly, it also indicates variable concentration of minerals such as calcium (Ca), magnesium (Mg) and potassium (K) under these treatments. The concentration of Ca, Mg and K detected under different postharvest ripening techniques are 0.163−0.257 mg\\100 gm, 0.212−0.431 mg\\100 gm and 0.675−1.802 mg\\100 gm respectively. Moreover, the respective concentration H, N, O and C are 41.56−46.51 gm/100 gm, 41.28−44.91 gm\\100 gm, 12.11−14.49 gm\\100 gm and 53.1−100.1 mg\\100 gm. Traces of arsenic (As) or phosphorous (P) were not found in samples treated with calcium carbide. Further studies on commercial grade fruits ripened with these agents are required to differentiate among nutritional elements of mango fruits treated under different ripening agents as well as to confirm the presence/absence of health hazardous elements.

Pure Shift Nuclear Magnetic Resonance: a New Tool for Plant Metabolomics.

Nuclear Magnetic Resonance (NMR) is one of the most powerful tools used in metabolomics. It stands as a highly accurate and reproducible method that not only provides quantitative data but also permits structural identification of the metabolites present in complex mixtures. Metabolic profiling by 1H NMR has proven useful in the study of various types of plant scenarios, which include the evaluation of cropconditions, harvest and post- harvest treatments, metabolic phenotyping, metabolic pathways, gene regulation, identification of biomarkers, chemotaxonomy, quality control, denomination of origin, among others. However, signal overlapping of the large number of resonances with expanded J-coupling multiplicities complicates the spectra analysis and its interpretation, and represents a limitation for classical 1H NMR profiling. In the last decade, novel NMR broadband homonuclear decoupling techniques through which multiplet signals collapse into single resonance lines - commonly called Pure Shift methods - have been developed to overcome the spectra resolution problem inherent to 1H NMR classical spectra. Here a step-by-step protocol of the plant extract preparation and the procedure to record optimal Pure Shift PSYCHE and SAPPHIRE-PSYCHE spectra in three different plant matrices - Vanilla plantleaves, potato tubers (S. tuberosum), and Cape gooseberries (P. peruviana) - is presented. The effect of the gain in resolution in metabolic identification, correlation analysis and multivariate analyses, as compared against classical spectra, is discussed.

Effects of Streamside Buffers on Stream Temperatures Associated With Forest Management and Harvesting Using DHSVM-RBM; South Fork Caspar Creek, California

Forest harvesting has been shown to effect water quantity and water quality parameters, highlighting the need for comprehensive forest practice rules. Being able to understand and predict these impacts on stream temperature is especially critical where federally threatened or endangered fish species are located. The goal of this research was to predict responses in stream temperature to potential riparian and forest harvest treatments in a maritime, mountainous environment. The Distributed Hydrology Soil Vegetation Model (DHSVM) and River Basin Model (RBM) were calibrated to measured streamflow and stream temperatures in the South Fork of the Caspar Creek Experimental Watersheds during critical summer periods when temperatures are highest and flows are low for hydrologic years 2010–2016. The modeling scenarios evaluated were (1) varying percentages of stream buffer canopy cover, (2) a harvest plan involving incrementally reduced stand densities in gauged sub-watersheds, and (3) an experimental design converting dominant riparian vegetation along set reaches. The model predicted a noticeable rise in stream temperatures beginning when stream buffer canopy cover was reduced to 25 and 0% retention levels. Larger increases in Maximum Weekly Maximum Temperatures (MWMT), compared to Maximum Weekly Average Temperatures (MWAT), occurred across all scenarios. There was essentially no difference in MWAT or MWMT between altering buffers along only fish bearing (Class I) watercourses and altering buffers along all watercourses. For the scenario with stream buffers at 0% retention, MWMTs consistently rose above recommended thermal limits for coho salmon(Oncorhynchus kisutch). Predictions when clearcutting the entire watershed showed less of an effect than simulations with 0% buffer retention, suggesting groundwater inflows mitigate stream temperature rises in the South Fork. The harvest simulation showed a small but consistent increase in MWATs (avg. 0.11°C), and more varied increases in MWMTs (avg. 0.32°C). Sensitivity analyses suggest potentially unrealistic tracking of downstream temperatures, making the vegetation conversion simulations inconclusive. Additional sensitivity analyses suggest tree height and monthly extinction coefficient (a function of leaf area index) were most influential on temperatures in the South Fork, which was consistent with other modeling studies suggesting management focus on tall, dense buffers compared to wider buffer widths.

Driving forces for recovery of forest vegetation after harvesting a subalpine oak forest in eastern Tibetan Plateau.

Uncertainty regarding how subalpine forest ecosystems respond to tree harvesting hinders their sustainable management and conservation strategies. To investigate the impact of oak (Quercus aquifolioides Rehd. et Wils.) harvesting and stand recovery processes on soil microbial communities and understory vegetation on the eastern Tibetan Plateau, we sampled and quantified the microbial community structure and understory vegetation in three age classes (1 year, 10 years, and 20 years since tree logging) of harvested stands and an un-harvested reference (control) stand of subalpine oak forest. Our result showed logging significantly altered the edaphic properties (p < 0.001) and shifted microbial community structure (p < 0.05), increasing the abundances of the Actinobacteria and arbuscular mycorrhizal fungi (AMF) but decreasing fungi and general, gram-positive and gram-negative bacteria. Post-harvest evolution increased the biomass of understory vegetation and reshaped its community. Fungi (18:1ω7c, 18:1ω9c) and gram-negative bacteria (18:2ω7c, cy19:0) abundances changed significantly (p < 0.01) after harvesting and during stand recovery, suggesting their potential use as indicators for post-harvest oak recovery. Structural equation modeling (SEqM) revealed that, via litter, residue, and edaphic properties, the recovery process indirectly promoted microbe abundance while the overstory vegetation regrowth inhibited the plant community's biomass in the understory. Microbial communities only had a minor, direct effect on understory vegetation. Litter and edaphic factors played important roles in reshaping understory plant and soil microbial communities for post-harvest evolution.

Harvest of Southern Highbush Blueberry with a Modified, Over-the-Row Mechanical Harvester: Use of Soft-Catch Surfaces to Minimize Impact Bruising

Harvest of fresh market, southern highbush blueberries (SHB) is labor intensive and costly, leading to a demand for alternative harvest methods. Recent research has shown potential for mechanically harvesting blueberries with minimal bruising by using a modified over-the-row (OTR) harvester. For two harvests, SHB cultivars Optimus and Vireo were either hand-harvested (HH) or mechanically harvested (MH) by two commercial harvesters, one unmodified with standard hard-catch surfaces (HCS) or by the other modified with soft-catch surfaces (SCS). For Harvest 1, fruit from all harvest methods were hand-sorted into the following categories: blue fruit (marketable), red fruit, green fruit and culls. Samples from each cultivar and treatment were then held at 24 °C overnight, and the following day firmness and impact bruise severity were determined. Harvest 2 had identical harvest treatments; however, the fruit were sorted on a commercial packing line prior to packing in clamshells (n = 16). A subsample was held overnight as in Harvest 1 for bruise severity rating, while the remaining fruit were stored at 1 °C for 14 days (d). Although percent marketable fruit was more affected by cultivar than harvest method, determination of bruise severity revealed the benefit of harvest with SCS over HCS for both cultivars. The former had 16–26% severe bruising, compared to 27–40% for the latter; HH had 1–4%. During storage, HH fruit remained firmer than HCS and SCS, which were similar. After 14 d, firmness for “Optimus” was 239 N (HH), 157 N (HCS and SCS) and for “Vireo” it was 189 (HH), 155 N (HCS and SCS). Fruit weight loss increased during storage (1.1–4.4%), but there was no difference due to catch plate surface. SSC, TTA and Ratio were not affected by catch surface type or storage period within cultivar. Using modifications such as “soft” catch surfaces on currently available OTR harvesters reduces impact bruise damage; however, impacts incurred during commercial packing operations can negate this effect. MH for fresh market blueberries may provide an economical alternative for blueberry growers; however, with current technology, the fruit should be utilized within a week of harvest.