•Shelterwood seed cutting combined with soil scarification can help to diversify tree regeneration.•A limited seed source and excessive deer browsing can hinder management efforts.•Limitation of seed ...can be a critical impediment for diversity of natural regeneration.•Integrated approaches may be necessary for increasing tree regeneration diversity.
Silviculture methods such as clearcutting, shelterwood seed cutting, and selection system are used to manipulate the canopy and regenerate new cohorts in hardwood stands. Additionally, site preparation can be utilized to alter seedbed conditions with the aim to promote changes in species composition. However, limited seed availability and increased ungulate browsing may limit successful natural regeneration in some areas. Our objective was to investigate the influence of regeneration method, site preparation, deer exclusion, and direct seeding on the regeneration of a managed northern hardwood forest. Utilizing a randomized split-plot design with three splitting levels, we examined the effects of four different regeneration methods, two site preparation treatments, seed limitation and deer browsing on composition, compositional heterogeneity, and richness of regenerating tree species. We observed significant differences in the resulting species composition related to the regeneration and site preparation methods. Shelterwood seed cutting implemented with 60% and 30% residual canopy cover, along with scarification, increased species richness and species compositional heterogeneity. However, the combination of deer exclusion and direct seeding resulted in the highest species richness across all treatment combinations. Deer exclusion alone did not enhance richness or compositional heterogeneity, highlighting the impeding effect of limited seed availability. We found that direct seeding successfully altered species composition and increased species richness. Our results suggest that while the regeneration and site preparation methods can benefit natural tree regeneration, approaches that also address both seed limitations and deer browsing will be necessary to increase the tree species diversity in some cases.
•Trillium cernuum was resilient to silvicultural treatments.•Scarification achieved in our study left most plants undisturbed.•Directly monitoring populations may be necessary to quantify treatment ...effects.
Contemporary and predicted declines in tree species diversity and forest resilience have prompted renewed interest in even-aged systems and/or site preparation to overcome bottlenecks to tree recruitment or facilitate range expansion of future-adapted species. The impact of this intensification on the herbaceous layer in forests traditionally managed with uneven-aged systems, however, is unclear, especially for uncommon dispersal limited species with heterogenous distributions. We leveraged a large-scale experiment (the Northern Hardwood Silvicultural Experiment to Enhance Diversity) to investigate the response of Trillium cernuum L., a somewhat uncommon and heterogeneously distributed non-clonal herb in our study system, to a gradient of canopy removal and soil disturbance. We monitored 16 small populations from 2015 (the year prior to treatment) to 2019 (3-years post treatment). Our results suggest that initial population size and stage structure were inextricably coupled with T. cernuum response. Independent of treatment, T. cernuum abundance and flowering generally increased over time commensurate with initial population size. Moreover, our study highlights the confounding effect of deer herbivory, which increased significantly following treatment. Collectively, our findings suggest that T. cernuum populations were resilient to canopy disturbance associated with single-tree selection and shelterwood harvests and the levels of scarification applied as part of our study. Higher levels of site impact or other site preparation methods such as herbicides will likely have greater impacts and warrant further investigation. Our results also suggest that directly monitoring populations of interest may be necessary to quantify treatment effects for uncommon and/or heterogenous species that are missed with common plot-based sampling designs or of conservation concern.
Urban Tree Selection for Diversity Hilbert, Deborah R.; Koeser, Andrew K.; Northrop, Robert J.
EDIS,
10/2020, Letnik:
2020, Številka:
5
Journal Article
Recenzirano
Odprti dostop
Urban tree diversity is important when attempting to create a healthy, beneficial, and resilient urban forest. Having a variety of trees can increase the aesthetic value for residents and create ...habitats for plants and animals. Some common street trees currently in the landscape are not site-appropriate and create infrastructure damage. By planting different types of trees in these locations, maintenance costs and infrastructure damage can be reduced and tree longevity increased. This new 4-page fact sheet is intended to provide urban foresters, arborists, landscape designers, and others in charge of tree planting with a process for introducing new species into the urban environment. Written by Deborah R. Hilbert, Andrew K. Koeser, and Robert J. Northrop, and published by the UF/IFAS Environmental Horticulture Department.https://edis.ifas.ufl.edu/ep589
Every year, hundreds of millions of migratory birds cross the Sahara to spend the northern winter in the Sahel. After their arrival in September the region does not receive any rainfall until June ...while temperatures increase. Birds inhabiting the Sahel have several strategies to cope with this seasonal advent of drought. Most ground-foraging and arboreal migrants actually remain in the desiccating Sahel, although Northern Wheatear Oenanthe oenanthe remains in the arid zone only in a wet year, but moves from the arid to the semi-arid zone in a dry year. Some arboreal migrants stay for 1–2 months in the Sahel during the early dry season, but move on to the more humid zone further south for the rest of the northern winter. Common Redstart Phoenicurus phoenicurus is the only Sahelian arboreal migrant that moves southward in this period. Counter-intuitively, Curruca species move northward after the early dry season to the arid zone where they concentrate in woody plant species whose attractiveness increases later in the dry season. This is either because those plants then gain berries (Toothbrush Tree Salvadora persica) or because they develop flowers (six desert species). In the semi-arid zone, tree-dwelling bird species disappear from tree species when these lose their leaves. However, in tree species which do not shed their leaves, bird numbers remain either constant (those using Desert Date Balanites aegyptiaca) or increase (those using Winter Thorn Faidherbia albida, a tree that foliates during the dry season). On floodplains bird numbers in acacia trees increase during the dry season. As a consequence, birds become concentrated in fewer tree and shrub species during their stay in the Sahel. After wet rainy seasons, trees have more flowers and leaves and shed them later, giving the birds more foraging space. At the end of their stay in Africa after dry rainy seasons, the number of arboreal birds is only half that after wet rainy seasons, suggesting higher mortality in dry years. Clearly, in such years mortality would be even higher without what can be seen as ‘refuge trees’: the acacias on floodplains, and Faidherbia and to a lesser degree Balanites in the rest of the Sahel.
As plantations become increasingly important sources of wood and fiber in arid/semiarid places, they have also become increasingly criticized for their hydrological impacts. An examination and ...comparison of gross rainfall (GR) partitioning across commonly-planted tree species (Pinus eldarica, Cupressus arizonica, Robinia pseudoacacia, and Fraxinus rotundifolia) in semiarid regions has great value for watershed and forest managers interested in managing canopy hydrological processes for societal benefit. Therefore, we performed a field study examining GR partitioning into throughfall (TF), stemflow (SF), and rainfall interception (I) for these species in the semiarid Chitgar Forest Park, Tehran, Iran. An advantage to our study is that we explore the effects of forest structural differences in plantation forests experiencing similar climatic factors and storm conditions. As such, variability in GR partitioning due to different meteorological conditions is minimized, allowing comparison of structural attributes across plantations. Our results show that commonly-selected afforestation species experiencing the same climate produced differing stand structures that differentially partition GR into TF, SF, and I. P. eldarica might be the best of the four species to plant if the primary goal of afforestation is to limit erosion and stormwater runoff as it intercepted more rainfall than other species. However, the high SF generation from F. rotundifolia, and low GR necessary to initiate SF, could maximize retention of water in the soils since SF has been shown to infiltrate along root pathways and access groundwater. A consideration of GR partitioning should be considered when selecting a species for afforestation/reforestation in water-limited ecosystems.
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•Measured rain partitioning of four most common species used in semiarid afforestation•Species rain partitioning differences are important in a water management.•Recommendations provided to guide tree species selection in semiarid urban greening
•3-PG model was validated for uneven-aged mixed-species forests.•This stand-level model accurately predicted the growth of structurally complex forests.•Simulations showed that climate change ...increased productivity by 17% since the 1930s.•Climate effects were due to increasing temperature, and to a lesser extent, vapour pressure deficit and CO2.
Stand-level process-based models have rarely been applied to uneven-aged forests that contain many size classes and negative exponential shaped size distributions. However, the relative simplicity of such models, in terms of parameterisation, use and interpretation, could make them valuable tools for studying and managing such forests. In particular, the effects of climate change on the stand-level growth of forests with negative exponential shaped size distributions has received very little attention compared with even-aged forests. The first objective of this study was to validate 3-PG, a stand-level process-based model, for five types of uneven-aged forests in Switzerland; (1) Fagus sylvatica dominated, (2) Picea abies dominated, (3) mixtures of Picea abies and Abies alba, (4) mixtures of Picea abies, Abies alba and Fagus sylvatica, and (5) mixtures of Larix decidua, Pinus cembra and P. abies. The second objective was to use 3-PG to examine how climate change has influenced the growth of these forests since the 1930s.
3-PG predictions of biomass, biomass partitioning in above- and belowground components, and light absorption were validated using inventory data from 23 plots, which had been monitored for an average of 81 years (15 to 112 years). For all species and size classes (2–3 per species), 3-PG produced accurate predictions of root biomass, stem biomass and outputs derived from it such as mean diameter, basal area and height, which were all highly correlated with the observed values (R2 > 0.86). The slope of predicted versus observed values was often not significantly different to 1 (averaged 1.13) and the bias averaged −1.2%.
3-PG simulations to examine the effects of climate change without the confounding effects of stand structure and management, showed that the growth of the five forests types has, on average, increased by 17% since the 1930s. The growth was mainly influenced by temperature, while in the case of A. alba, growth was largely influenced by vapour pressure deficit. The accelerated growth rates imply that thinning intensities also need to increase to prevent high stand densities from inhibiting regeneration in these uneven-aged forests. This study shows that 3-PG can be used to predict the growth dynamics of uneven-aged mixed-species forests, and to our knowledge, this is the first time a stand-level process-based forest growth model has been used and validated for such forests.
•Proposing an new evolutionary forest forecaster for global solar irradiance.•Forecasting six steps ahead simultaneously using the evolutionary forest.•Evaluating the generalizability of the proposed ...model under six climatic sites.•Examining the proposed approach using endogenous, exogenous and hybrid inputs.•Comparing the proposed approach with benchmarking models and the naive model.
The increasing integration of solar sources into the energy mix presents significant challenges, particularly in short-term energy management. Accurate solar irradiance forecasts can greatly assist solar power plant operators and energy network managers in making informed decisions about energy production and consumption. This paper aims to develop a new accurate forecasting model for short-term global solar irradiance based on an innovative evolutionary forest approach. Our model, baptized EFITS, performs incremental tree selection through appropriate evolutionary operators maintaining a good tradeoff between accuracy and diversity, generating progressively near-optimal decision trees to construct the final evolutionary forest forecaster. This new evolution process also automatically selects near-optimal input parameters, enhancing the overall model accuracy and generalization ability. Six climatically diverse locations in Morocco and three types of inputs (endogenous, exogenous, and hybrid) are used to assess the performance of the proposed. The results demonstrate that our proposed model exhibits excellent performance across all studied sites and horizons. Among all input types, hybrid inputs delivered the best forecasting accuracy across all studied sites and horizons. Notably, the continental climate site (Bni Mellal) achieved the highest accuracy, with nRMSE ranging from 4.94% to 7.54% and nMBE from 0.71% to −0.46% for 1 to 6 h forecasts. Conversely, Ifrane city, characterized by a humid temperate climate, showed the lowest accuracy, with nRMSE ranging from 10.34% to 18.94% and nMBE from 1.21% to −1.54%. Finally, a detailed comparison with benchmarking models (random forest, bagging, gradient boosting, single decision tree, bidirectional long short-term memory network, and scaled persistence models), revealed that our model consistently outperforms them across all tested scenarios, locations, and forecasting horizons.
•Low intensity single-tree selection cuttings generally increased tree growth.•Soil moisture increased by 10% after treatments, mostly in the growing season.•Best tree growth models included data on ...management, competition and soil moisture.•Close-to-nature forestry appears as a promising tool to reduce drought vulnerability.
Given the rising frequency of drought events, close-to-nature principles appear to be a suitable management option for promoting more adapted forests by increasing diversity and vitality (e.g., enhancing tree growth), while preserving soil moisture. In this study, we evaluate individual tree growth from selected trees (including future crop trees) and soil moisture responses to close-to-nature silvicultural treatments in sub-humid Mediterranean mixed forests in Catalonia (Northeastern Spain). We relied on 18 permanent sample plots (i.e., 9 paired-plots: managed / control) representing a competition intensity gradient and different forest types (dominated by either Quercus ilex, Castanea sativa, Quercus pubescens/petraea, Pinus pinea and Pinus sylvestris). From them, 8 plots were subject to intense monitoring in terms of intra-annual tree radial growth, monitored by manual band dendrometers, and hourly soil water content. Basal area increment, and annual and seasonal (May, June, July) radial increment rates were computed as a proxy of tree growth for all plots and for those plots with dendrometers, respectively. We conducted Spearman correlation analyses between tree growth, competition intensity, soil water content and climatic variables to detect significant relations between forest management and variables of interest (e.g., basal area increment, radial increment rates, soil water content). To investigate further into the effect of this silviculture on tree growth, we used mixed-effects models using as predictors variables related to competition intensity and forest management (dummy variable) in combination with monthly soil water content variables. We observed that basal area increment and radial increment rates had a positive (albeit weak) correlation with forest management, while competition intensity had a negative correlation with both variables. The models were not capable of detecting clear species-specific tree growth responses to competition. Compared to control plots, on average, the treatments boosted soil water content by about a 10% in managed plots in Q. ilex, P. sylvestris and P. pinea stands, and this increase was particularly significant during the growing season. Moreover, the best-fitted model predicted seasonal radial increment rates using not only forest management and competition variables, but also monthly soil water content factors. Our results suggest that close-to-nature-forest management may reduce the vulnerability to drought by increasing tree vitality and soil moisture, at least in the short term (<3 years).
•Silvicultural treatments had little relation to Betula alleghaniensis seedling densities.•Conspecific basal area and litter depth heterogeneity promote B. alleghaniensis.•Seedling and sapling ...composition relates to microsite environment.
Conventional forestry practices in Great Lakes northern hardwoods tend to promote the regeneration of a few economically important tree species, and may consequently contribute to a decline in mid-tolerant species abundance and tree species diversity. Using a greater variety of silvicultural systems to emulate a range of historical disturbances may help to restore historical mid-tolerant species abundance and tree diversity. To test the link between seedling recruitment and sapling recruitment and disturbance-based management systems, we implemented a novel silvicultural experiment using a variety of harvest and site preparation treatments ranging from single-tree selection to clear-cut and scarification, which emulate regionally-specific natural disturbance regimes. We predicted that mid-severity harvest treatments would promote mid-tolerant sapling recruitment, while scarification and the creation of pit-mound topography would favor recruitment of small-seeded species such as yellow birch (Betula alleghaniensis Britt.). We found that seedling and sapling composition was related to silvicultural treatment and driven by an opposing gradient of canopy openness and leaf litter depth along with temporal soil water content variation. Yellow birch seedling density, however, had little relation to silvicultural treatment but was instead predicted by positive relationships with leaf litter depth variation and residual conspecific basal area. Our findings suggest that silvicultural systems aimed at promoting species diversity in northern hardwoods should consider, along with conventional techniques, modifying litter depth and canopy openness while retaining seed trees.
Malabar Giant Squirrel (Ratufa indica indica) is one of the four subspecies endemic to India (Abdulali 1952), common to northern and central Western Ghats among species Ratufa indica belonging to ...Subfamily Ratufinae. The study was designed to analyze the nest tree preferences of animals in the dry deciduous forests of the Umblebyle range, Shimoga, Karnataka (South India) during February, March, and April 2021, surveying 20 transects covering a distance of 47.7 km. Nest tree preferences were assessed by observing 406 dreys (nests) on 385 trees covering an area of 8350.89 ha. The nest trees came from 20 families and 41 species, with 12 tree species in the Family Fabaceae and 84 trees in the Terminalia paniculata having the highest preference. The Squirrels showed the highest preference for deciduous trees over semi-evergreen and evergreen trees. The most preferred tree height and nest height ranged between 11-20m, including 87.53% of nesting trees and 83.89% of nests, respectively. The average nest height was estimated to be 14.73 (±3.311) m, with a minimum and maximum height of 7 m and 28 m, respectively. The difference between average tree height and average nest height was 1.512m.
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