Tree Shelters Research Articles

Does forest age affect soil biodiversity? Case study of land snails in Mediterranean secondary forests

Based on a sampling design used for vascular plants, the effect of forest age (i.e. the time in years since a land patch became a real forest patch as a measure of temporal continuity of forest characteristics) on land snail richness, abundance and composition was assessed in 18 plots in Mediterranean evergreen and deciduous oak forests, belonging to four Sites of Community Importance in Italy. Most examined plots belong to young forests; in particular, three age classes were considered (class 1, <22 years; class 3, 38–56 years; class 5, >77 years). Twenty-seven species and 2433 individuals were recorded. Box plots showed that forest age did not seem to be a key factor for land snail species richness and abundance at least in the time range of examined forests. However, this may not be true, if real old-growth forests are considered. No differences between evergreen and deciduous forest were found too. With regard to species composition, Non-metric multidimensional scaling demonstrated an assemblage of species widespread in all forest age classes, while Indicator Species Analysis failed to identify any species as indicator for any age category. This shows that a process is underway but has had insufficient time to differentiate assemblages and to accumulate the majority of rare species, due to the young nature of examined forests. Habitat structure may affect communities more than forest age: suitable microhabitats (a few old/very old trees for shelter) are a sufficient prerequisite for land snail diversity, ensuring community survival and protection, irrespective of forest age class. These findings highlight the importance of habitat structural complexity at local scale for preserving invertebrate diversity in Mediterranean secondary forests.

Assessing the Efficacy of Seedling Planting as a Forest Restoration Technique in Temperate Hardwood Forests Impacted by Invasive Species

The emerald ash borer (Agrilus planipennis Fairmaire; EAB) is an invasive insect that causes mortality of trees in the genus Fraxinus, creating canopy gaps that may facilitate invasion by exotic plants. Planting native tree seedlings under EAB-infested Fraxinus may accelerate succession and preclude invasive plant expansion; however, the effectiveness of this approach has not been experimentally tested. We assessed understory seedling planting of Quercus rubra, Carya laciniosa, and Juglans cinerea in EAB-infested forests, where the invasive shrub Lonicera maackii (Amur honeysuckle) was removed. We tested whether the use of plastic tree shelters (“tree tubes”) or planting season (fall versus spring) contributed to the success of the reforestation plan by measuring growth rates (cm/yr) and survivorship two and seven years after planting. After seven years, seedling survivorship was &lt;25% for all species and planting techniques. Quercus rubra exhibited poor survivorship with one seedling surviving to the conclusion of the experiment. Juglans cinerea and C. laciniosa had higher survivability and growth rates than did Q. rubra after two and seven years. Effects of tree tubes were weak and temporary. After 2 years, Q. rubra seedling survivorship was higher in tree tubes; however, by the end of the experiment 29 of the 30 Q. rubra seedlings in tree tubes had died. Juglans cinerea seedlings grew faster when planted in the fall compared to the spring, but overall survivorship of these seedlings was unaffected by planting season. Neither the use of tree shelters nor the planting season contributed to the growth or survival of C. laciniosa seedlings. In summary, our results indicate that seedling planting of Carya and Juglans may be a useful way to increase biodiversity in regenerating forests; however, the resource-expensive processes of over-wintering seedlings and using tree shelters may not increase the success of reforestation efforts.

Survival, Height Growth, and Phytoextraction Potential of Hybrid Poplar and Russian Olive (Elaeagnus Angustifolia L.) Established on Soils Varying in Salinity in North Dakota, USA

Salt-affected soils in the Northern Great Plains, USA, can impact the long-term survival and growth of trees recommended for agroforestry systems, with Russian olive (Elaeagnus angustifolia L.) being one of few options that survives on these sites. Similarly, hybrid poplars have been used for phytotechnologies on high-salinity soils throughout the world. The objective of this study was to test the survival, height growth, and phytoextraction potential of eight hybrid poplar clones (Populus deltoides Bartr. ex Marsh. × P. nigra L. ‘Robusta’, ‘DN17’, ‘DN182’, ‘DN5’; P. deltoides × P. maximowiczii A. Henry ‘NC14104’, ‘NC14106’; P. nigra × P. maximowiczii ‘NM2’, ‘NM6’) versus Russian olive grown on soils categorized according to initial salinity levels: low (0.1 to 3.9 dS m−1), medium (4.0 to 5.9 dS m−1), and high (6.0 to 10.0 dS m−1). Seven trees per genotype were grown in each salinity treatment at a spacing of 3 × 3 m for four years in Burleigh County, North Dakota. Survival and height were determined following the first four growing seasons, and leaf phytoextraction potential of Al, Ca, Cd, Fe, K, Mg, Mn, Na, and Zn was measured for one-year-old trees. Soil salinity decreased over time, reflecting the phytoextraction potential of the trees. Russian olive did not survive as well as expected, having lower overall survival than three of the hybrid poplar clones (‘DN17’, ‘DN5’, ‘NM6’). At the end of three years when trees were removed per a landowner maintenance agreement, 86%, 71%, and 43% of the Russian olive trees were alive in the low-, medium-, and high-salinity soils, respectively. At this time, ‘NM2’ was the only hybrid poplar clone with similar survival to Russian olive in the high-salinity soils. Russian olive had greater Na, Cd, and Fe leaf concentrations than the hybrid poplar clones, but it also had the worst uptake of Ca and Mg of all genotypes. For hybrid poplar, the P. deltoides × P. nigra genomic group had the broadest clonal variability among all traits, with ‘Robusta’ and ‘DN182’ exhibiting great potential for establishment on high-salinity soils. ‘Robusta’ and ‘DN17’ are the same genotype but they came from different nursery sources (i.e., hence their different nomenclature), and they did not differ for height nor leaf phytoextraction. Populus deltoides × P. maximowiczii clones were not suitable for the soil conditions and silvicultural applications (e.g., tree shelters) of the current study, while P. nigra × P. maximowiczii clones exhibited the most stable performance across all years and salinity treatments. Both ‘NM2’ and ‘NM6’ had superior fourth-year survival and height, as well as average or above average phytoextraction of all elements tested.

Reforesting Appalachian Surface Mines from Seed: A Five-Year Black Walnut Pilot Study

Research Highlights: We found promising success for black walnut (Juglans nigra L.) planted on a legacy surface mine. Our results indicate that direct seeding can be an effective restoration method, and that shelters may not be needed. Background and Objectives: Reforestation in the Appalachian coalfields has primarily relied on the planting of nursery stock late in the dormant season. This study examined the use of direct seeding during the fall, a practice that, if successful, could both reduce costs of planting and open up a new season for reforestation planting. Black walnut is of particular value for wildlife habitats, timber value, and even human nutrition. In addition, it normally occurs in diverse forests with rich soils of the region. Therefore, establishment on previously surface-mined lands may indicate a positive successional trajectory and resilience. Materials and Methods: This study took place in eastern Kentucky, USA, on a site that was surface mined from 1996 to 2000 and subsequently reclaimed as a wildlife habitat. In 2010, the site was decompacted according to the Forestry Reclamation Approach (FRA) by deep ripping with a bulldozer, and in November 2011, a 2 × 2 factorial experiment was initiated to compare the growth of walnut trees planted either by seed or as one-year seedlings, and either with or without tree shelters. Each treatment (four total: Unsheltered Seedling, Sheltered Seedling, Unsheltered Seed, and Sheltered Seed) had three replicate plots of 17 × 9 m, with 50 seeds or seedlings planted per plot. Measurements (survival, height, diameter, and volume) were made in 2012, 2013, and 2016. Effects of planting type and shelter presence, as well as their interaction, were analyzed using linear mixed models. Results: Planting type was significant for all measurements in the first two years (seedlings &gt; seed), but this difference was largely diminished by 2016. There was a significant interaction of the two main effects, such that shelters benefited (or did not affect) those trees planted as seedlings, but hindered those planted from seed.

Impact of internally displaced persons on forest and vegetation of Jere LGA, Borno State, Nigeria

Deforestation is described as changes in the structure and composition of an area of forest after there has been some form of human intervention such as firewood, charcoal and logging. The study examined impact of internally displaced persons (IDPs) on forest and vegetation cover of Jere L.G.A. of Borno State, Nigeria. The objectives of the study were to determine the extent of impact of deforestation and depletion of vegetation cover caused by displaced persons to forest of Jere L.G.A. and also identifies the socio-economic needs of the displaced persons in camps. Data were collected from both primary and secondary sources. Primary data were generated through field observation and focused group discussion with displaced persons, while the secondary data was obtained from relevant available literature. Findings revealed that about 12 square kilometers of forest and vegetation cover were destroyed by displaced persons. The Findings also revealed that displaced persons engaged in cutting of trees for shelter, firewood, charcoal and debarking trees for medicinal purpose to earn money. The study revealed displaced persons conditioned in camps are deplorable far from the ideal situation. The study concluded that environmental impact assessment should be incorporated in the strategies for displaced persons welfare before their arrival. The study recommended that host governments, humanitarian agencies and NGOs should support the living conditions of displaced persons through socio-economic, education, skill and vocational training development that promotes lifelong learning opportunities.Keywords: Displaced persons, Deforestation, Vegetation, Firewood and Charcoal

Production and establishment techniques for the restoration of Nothofagus alessandrii, an endangered keystone species in a Mediterranean forest

Ruil (Nothofagus alessandrii) is an endangered keystone species from the Mediterranean climate zone of Chile. Ruil’s fragile state of conservation urges development of restoration programs, but specific protocols for nursery production and field establishment that ensure plant survival are largely unknown. Therefore, we examined the effect on nitrogen (N) fertilization and container size during nursery production in combination with the use of mesh shelters after outplanting on survival and growth during the first growing season in the field. First year outplanting survival of nursery-grown container seedlings was enhanced when seedlings were given nitrogen (N) during nursery production and deployed with mesh tree shelters in the field. The volume of the container had no effect on outplanting survival and growth. Increasing N from zero to 200 mg N L−1 provided sufficient N levels, resulting in increased seedling height, root-collar diameter, shoot biomass, and total seedling N and phosphorous concentrations. Additional N provided by the 400 and 600 mg N L−1 treatments underwent luxury consumption by the seedlings with no further benefits in field performance. Improved growth in the nursery, along with the use of mesh tree shelters after outplanting, especially during the typical summer drought, may be responsible for increased survival during the first growing season. Increasing the performance of nursery-grown ruil seedlings is essential to restoring this endangered, vulnerable, and foundation species within the highly biodiverse, yet seriously threatened endemic Maulino Costero Forest of the Mediterranean climate of central Chile.

The Effect of Polypropylene Tree Shelters on Growth and Survival of Pedunculate Oak Seedlings (Quercus robur L.)

Background and Purpose: The declining and dieback of lowland oak forests as the result of global climate change, as well as the attack of various pathogenic organisms, industrial pollution, and other negative effects reduce acorn yield and will continue to do so in the future. As a result of this fact, the areas on which artificial regeneration will be applied by planting seedlings will have to be increased. The artificial regeneration process is more expensive than the natural one, so protection measures need to be applied to minimize the loss of young seedlings. Materials and Methods: Experimental plots were set up in the forest area of Spačva Basin. A completely randomized block design experiment in four repetitions was used, in which four variants of planting and protection of oak seedlings were examined. We tested polypropylene tree shelters and hydrophilic superabsorbent based on maize starch. Heights of the plants were measured by measuring tape, and survival was registered by numbering of dead and living plants. For statistical purposes, we have used analysis of variance (repeated measure ANOVA), which allows us to prove statistically significant difference between morphological traits of studied variants. Results: Two years after planting, the lowest level of survival was found in unprotected seedlings (79.5%), while tree shelters provided the best conditions for seedlings survival (88.75%). In the case with the hydrophilic granules Zeba the result is slightly worse. When analyzing average height in a particular case, significantly higher plants are recorded in cases where the polypropylene tree shelters are used. The average height, with tree shelters (128.27 cm), is more than three times higher than the unprotected seedlings (37.97 cm). The addition of hydrophilic granules did not show a statistically significant difference. In cases where the seedlings were not under the tree shelter protection, the effect of hydrophilic granules was also not statistically significant. Conclusions: Sheltering accelerated the height growth of the planted oaks substantially and also provided best conditions for seedlings survival. During the research period the usage of Zeba did not justify the purpose for which it was applied. Although the first results are promising in order to gain a complete insight into the potential of tree shelters it is necessary to record the changes and maintain the experiment for a further 2-3 years with quantification of other harmful factors that may appear (drought, game etc.) after which a more reliable judgment regarding their usefulness could be provided.

Application of polarized light compass system on solar position calculation

In order to satisfy the polarization navigation requirements for the solar position calculation, a new method based on improved polarization angle model by using a three-channel polarization imaging system is proposed. The system consists of three microminiature TFT-LCD optical cameras equipped with three fish-eye lenses, making the structure more compact and smaller. Compared with common method based on spot detection, the proposed method has the advantages of wide field of view and high precision. First of all, the simulation based on optimization algorithm is carried out under different initial values. Then the three-channel polarization imaging system is used to verify the improved polarization angle model in three kinds of weather conditions. The experiment showed that: (i) under clear weather, the solar altitude angle and azimuth errors of the solar position calculated at different times are 0.018° and 0.028°; (ii) in building shelter environment, the solar altitude angle and azimuth errors of the solar position are 0.167° and 0.1°; (iii) in tree shelter environment, the solar altitude angle and azimuth errors of the solar position are 0.921° and 0.25°. Compared with the traditional method, the precision is enhanced at maximum 60.87% by using the proposed method.

Factors affecting abundance of different stages of the endophilic tick Ixodes anatis in brown kiwi (Apteryx mantelli) shelters

Ixodes anatis is a species of endophilic (nidicolous) tick species parasitizing brown kiwi (Apteryx mantelli). Even though they are endemic to New Zealand like their host, very little is known about these ticks or their population dynamics and relationships with their hosts. We conducted a study from May 2013 to June 2014 to evaluate the effect of shelter location (one of three gullies), habitat (forest, scrub and pasture) and type (tree, soil and surface) on the abundance of the different life stages of I. anatis. In total, 12,172 ticks were collected from 63 shelters, which were sampled monthly for 11 months over the 14 month period. Un-engorged larvae predominated over other stages accounting for 87.2% of the samples collected. We found that location, habitat in which the shelters were located, and the type of shelter were significant predictors of I. anatis abundance. Tree shelters in forests had significantly higher tick abundance than those in scrub and pasture. Tree and soil shelters in general had significantly more ticks than surface shelters. Shelters located in Kauri Bush a drier site, had higher abundances than those in wetter sites. While some of these changes can be explained with the movement of the host, we believe more research needs to be done on the effect of shelters’ microclimate on I. anatis’ life cycle.

Riparian and Upland Afforestation: Improving Success by Excluding Deer from Small Areas with Low Fencing

We propose that small patches of land protected by low (1.2-m tall) fence is a viable approach for restoring and/or conserving forests in riparian or upland areas with high white-tailed deer (Odocoileus virginianus Zimmerman) populations. We also propose that this new approach may be advantageous because, unlike tree shelters, fenced areas protect shrubs just as well as trees in afforestation projects. Multi-year field experiments were performed involving deer exclosures where fence height and fenced area were manipulated in upland and lowland pasture and forest settings. Results show that low fencing significantly increased seedling survival and growth relative to unfenced areas when fenced areas were small (i.e., less than or equal to ∼100 m2). Moreover, tall fencing (1.8 or 2.3 m) did not provide significantly greater protection than shorter (1.2-m) fencing when the fenced areas were kept small. We propose that creating small patches of deer-free pasture or forest habitat will greatly support new approaches to afforestation such as applied nucleation. Finally, we show that low-stature fencing may also have application for protecting larger areas (≥0.8 ha) if the fencing is deployed around the perimeter as two low fences erected in parallel and with a small (3-m) space between them. We conclude that low fencing can result in levels of survival and growth of both trees and shrubs suitable to meet the success criteria for afforestation projects funded by the US federal government.

Ecological Factors Affecting White Pine, Red Oak, Bitternut Hickory and Black Walnut Underplanting Success in a Northern Temperate Post-Agricultural Forest

This study took place in southern Québec (Canada) where young stands of white ash and grey birch have been underplanted with white pine, red oak, bitternut hickory and black walnut. The establishment success of white pine and red oak was measured with and without tree shelters (to protect from deer). Ecological factors affecting the height growth of the four species were also measured for protected trees. After 6 years, the survival and total height of unprotected oak was 29% and 44.3 cm vs. 80.5% and 138.5 cm for protected oak. White pine was less affected by browsing (survival of 79.5 and 93.5%; height of 138.5 and 217.9 cm for unprotected vs. protected pine). Height of white pine was higher in the grey birch stands, while height of all hardwoods was higher in the white ash stands, which had better soil drainage, higher fertility, and an understory dominated by Rubus species. Total height of all hardwoods was significantly (p &lt; 0.05) correlated with Rubus cover and with soil fertility. Pine and walnut height were strongly correlated (p &lt; 0.001) to shelterwood structure (canopy openness or total basal area). Pine was less sensitive to variations in shelterwood characteristics, while black walnut showed high sensitivity. This study provides evidence that underplanting is suitable for black walnut assisted migration northward and for bitternut hickory restoration, despite soil conditions that were less favorable than in bottomland habitats mainly supporting these species in eastern Canada. Tree shelters offering protection from deer browsing and species-specific site selection are recommended for underplanting in the southern Québec region.

Should we use meshes or solid tube shelters when planting in Mediterranean semiarid environments?

Tree shelters in Mediterranean environments have a two-sided effect. They not only protect seedlings from browsing but also ameliorate microclimatic conditions, improving post-planting survival and growth. However, the ecophysiological basis of these effects are poorly understood. A factorial experiment combining light transmissivity and shelter type (solid tube vs. mesh wall) was carried out to assess the impact of contrasting microclimatic characteristics on seedling performance and physiological stress levels of shelters in two Mediterranean shrubland species (Quercus coccifera and Rhamnus lycioides) planted in a semiarid site. Even though seedlings in solid tube shelters experienced higher temperature and were slightly more photoinhibited, they had higher predawn water potential and, in general, better survival and growth than in mesh wall shelters. However, these effects were species-specific, with Rh. lycioides more favoured by solid wall shelters than Q. coccifera. However, root growth cannot explain these interactions between species and shelter type on seedling survival. Since light transmission had a marginal effect compared with wall type, we proposed that the observed effects and interaction with species are not dependent on light intensity or temperature but on other microclimatic differences like air velocity or light quality and distribution. Further studies should assess the importance of these factors on post-planting growth and physiological stress levels, which can be critical for matching the correct tree shelters type for each species in plantations in semiarid environments.

Beneficial effect of hot spring bathing on stress levels in Japanese macaques.

The ability of animals to survive dramatic climates depends on their physiology, morphology and behaviour, but is often influenced by the configuration of their habitat. Along with autonomic responses, thermoregulatory behaviours, including postural adjustments, social aggregation, and use of trees for shelter, help individuals maintain homeostasis across climate variations. Japanese macaques (Macaca fuscata) are the world's most northerly species of nonhuman primates and have adapted to extremely cold environments. Given that thermoregulatory stress can increase glucocorticoid concentrations in primates, we hypothesized that by using an available hot spring, Japanese macaques could gain protection against weather-induced cold stress during winter. We studied 12 adult female Japanese macaques living in Jigokudani Monkey Park, Japan, during the spring birth season (April to June) and winter mating season (October to December). We collected faecal samples for determination of faecal glucocorticoid (fGC) metabolite concentrations by enzyme immunoassay, as well as behavioural data to determine time spent in the hot springs, dominance rank, aggression rates, and affiliative behaviours. We used nonparametric statistics to examine seasonal changes in hot spring bathing, and the relationship between rank and air temperature on hot spring bathing. We used general linear mixed-effect models to examine factors impacting hormone concentrations. We found that Japanese macaques use hot spring bathing for thermoregulation during the winter. In the studied troop, the single hot spring is a restricted resource favoured by dominant females. High social rank had both costs and benefits: dominant females sustained high fGC levels, which were associated with high aggression rates in winter, but benefited by priority of access to the hot spring, which was associated with low fGC concentrations and therefore might help reduce energy expenditure and subsequent body heat loss. This unique habit of hot spring bathing by Japanese macaques illustrates how behavioural flexibility can help counter cold climate stress, with likely implications for reproduction and survival.

Establishment success of seven hardwoods in a tree-based intercropping system in southern Quebec, Canada

In temperate tree-based intercropping (TBI) systems, good survival and early growth of selected tree species without wood defects is critical, when taking into account both economic considerations and rapidly accruing environmental benefits that are provided by the trees. The establishment success of different tree species that have contrasting growth strategies in Northeastern American TBI systems have not been assessed in a well-documented manner, which is an important influential barrier limiting their adoption by farmers. We analyzed establishment success after five growing seasons of six hardwood species and four hybrid poplar clones in a 50 stems ha−1, tree-based intercropping system. The hardwood species being evaluated were Carya ovata, Juglans nigra, Quercus bicolor, Quercus macrocarpa, Quercus rubra, and Acer saccharum. The hybrid poplar clones being evaluated were four clones of Populus deltoides × P. nigra × P. maximowiczii. We also compared 3-year-old bareroot (165 cm in height) with tree shelter versus 6-year-old root-balled transplants (370 cm in height) without tree shelter for two hardwood species (Quercus rubra and Acer saccharum). Mean survival rate of the six hardwood species originating from 3-year-old transplants was 70% after 5 years. Acer saccharum (33%) and Carya ovata (57%) had the lowest survival rates. Tree height of Quercus bicolor and Quercus macrocarpa was taller than that of Carya ovata, Juglans nigra and Quercus rubra. Tree height of Acer saccharum was intermediate among species. Mean survival rate of hybrid poplar after five growing seasons was 82% and did not differ among the clones. Growth of DN 4813 was lower than that of DN×M 915508, DN 3570 and DN 3585. Tree external defects (forks, frost cracks, trunk inclinations, trunk wind bends, and physical injuries) were observed in 63% of the hardwoods and 55% of the hybrid poplars. Red oak and sugar maple originating from 6-year-old transplants had survival rates of 100%. Over 5 years, height increment of 6-year-old transplants was higher than that of 3-year-old transplants. The 6-year-old transplants of Quercus rubra and Acer saccharum were the most cost-effective stock type. We conclude that tree survival, tree growth and tree external defects in establishment phase of TBI systems may vary considerably across hardwood species, hybrid poplar clones and planting stock type.

Influence of mulching and tree shelters on 4-year survival and growth of zeen oak (Quercus canariensis) seedlings

We assessed the effect of mulching and tree shelters on the establishment and early growth of zeen oak (Quercus canariensis Willd.) during the first 4 years after planting in Northwestern Tunisia. Five mulch types (Italian Stone Pine (Pinus pinea L.), Lentisk (Pistacia lentiscus L.), and a combination of Italian Stone Pine and Lentisk (organic mulches), gravel (inorganic mulch) and control), and three tree shelter types (non-vented and vented tree shelters, and control) were tested. An increase in the number of internodes occurred under the gravel mulch, while a reduction in survival was found for the lentisk mulch. Tree shelters had no effect on survival, but increased mean height growth and reduced mean diameter growth during the 4 years (excepting a non-significant effect for vented tree shelter at year four). Comparison of the annual shoots and growth units (GU) between sheltered and unsheltered plants according to year of formation revealed two growth phases. In first phase, shoots were totally or partially inside the shelters; mean length of annual shoots and GU were greater for sheltered plants. The second phase was characterized by shoots emerging from shelters; mean length of annual shoots and GU were similar for all plants, with or without tree shelters. Results suggest that the use of tree shelters, particularly vented shelters, could contribute to the improvement of the artificial regeneration of zeen oak. The use of mulching alone or in combination with tree shelters did not improve zeen oak performance in the field.

ROAD AND LANDSCAPE FEATURES THAT AFFECT BAT ROADKILLS IN SOUTHEASTERN BRAZIL

The most studied impact on road ecology is roadkill, however, there is little information about the relations between highways and specific groups like bats. This study intended to identify the species of bats roadkilled and to evaluate the existence of temporal fluctuation between the roadkill rates, specific stretches of the road with higher rates, and characteristics of the road/landscape that may influence those rates. We encountered at least nine bat species among 65 roadkills (most Phyllostomidae), which comprise a subgroup of the local fauna that presents ecologic features that make them susceptible to being hit, especially Artibeus lituratus. The medium roadkill rate was of 0.01 individuals/km/day of monitoring, and there was no significant temporal variation. We identified five hotspots through special 2D HotSpot Identification Analysis. The selection of theoretical models through Generalized Linear Models showed that roadkill occurrence has a positive relation with vehicular traffic and negative relation with presence of marginal pasture and forests. As the major part of records was of species that are tolerant to human-disturbances, the increase in traffic consequently affected a higher number of bats capable to explore the area occupied by the road. The presence of native forest close to the road can lead to a decrease of animals hit by vehicles, once it offers more resources and favorable habitats, which reduces the need for bats to cross the roads for foraging. On the other hand, many species that necessarily depend on areas sheltered by trees for shelter, and do not possess the ability to fly long distances do not occur in open areas such as pastures. In this context, we suggest that the main measure of mitigation regard bat species would be the traffic control through speed limit, especially on the roadkill hotspots areas.

Thermal Degradation Kinetics of Virgin Polypropylene (PP) and PP with Starch Blends Exposed to Natural Weathering

The objective of this work is to study the thermal degradation kinetic parameters of polypropylene (PP) and compare them to those of a polypropylene/starch blend (PP/S) (70/30 (wt %)), taking into account the effect of photodegradation caused by natural weathering. Samples were taken from tree shelters exposed to four years of natural weathering and compared to the unexposed material stored under laboratory conditions. Nonisothermal (dynamic) thermogravimetery was used with five different heating rates (β): 5, 10, 15, 20, and 25 °C min–1. Several analytical model-free methods were used to determine the kinetic parameters, including the Friedman, Coats and Redfern, Kissinger, and Flynn–Wall–Ozawa (FWO) methods. The model-fitting method of Criado was also applied to determine the optimal mechanism of degradation that the polymers followed. In addition, an analytical solution was developed to mathematically model the experimental data and estimate the kinetic parameters. The analytical approach was developed...

Impacts of mulching and tree shelters on cork oak (Quercus suber L.) seedling survival and growth after four growing seasons

Effet du paillage et des abris-serres sur la survie et la croissance de plants de Chêne-liège (Quercus suber L.) durant quatre saison de croissance. Cinq modalités de paillage (Pin pignon, Lentisque, mélange de Pin pignon et de Lentisque (paillages organiques), gravier (paillage inorganique) et témoin), ainsi que trois modalités d’abris-serres (non aérés, aérés et témoins) ont été testées. Aucun des deux types d’abris-serres aéré et non aéré n’a eu d’effet significatif sur le taux de survie des plants, alors qu’ils ont significativement augmenté la croissance en hauteur moyenne des plants, par rapport au témoin, respectivement de 74-104% et 93-106 % durant les quatre années. Contrairement à la croissance en hauteur, le diamètre moyen de la tige à la base des plants des abris-serres aéré et non-aéré a été significativement plus petit que celui du témoin, durant toute la période d’étude, respectivement de 23-31 % et 38-42 %. Les abris-serres ont significativement affecté le microclimat autour des plants par augmentation ou diminution de la température, de l’humidité relative et du déficit de pression de vapeur de l’air. Ils ont réduit, par ailleurs, le taux de photosynthèse, et donc la production en biomasse totale, en raison du faible niveau lumineux. L’augmentation de la largeur et l’aération des abris pourraient aider à diminuer la température et augmenter la transmission de la lumière, ce qui pourrait les rendre plus favorables à la croissance des plants. Le paillage n’a pas eu d’effet significatif sur la croissance des plants durant toute la période d’étude. L’utilisation combinée des abris-serres et du paillage n’a pas amélioré la croissance des plants.

「積雪寒冷地における緑化工技術の課題解決に向けて」 六角柱型ツリーシェルターの耐雪性

「積雪寒冷地における緑化工技術の課題解決に向けて」 六角柱型ツリーシェルターの耐雪性

Evaluation of dryland riparian restoration with cottonwood and willow using deep‐planting and herbivore protection

Degradation of dryland riparian ecosystems has been linked to the lowering of alluvial groundwater tables and reduced floodplain connectivity. Establishing riparian plants in dryland ecosystems with high water‐stress and herbivore pressure presents major challenges for restoration practitioners. By planting at sufficient depths to reach lowered water tables, deep‐planting provides direct access to water and encourages root development within hydrated soils. While deep‐planting is a promising alternative to traditional supplemental irrigation in dryland areas affected by lowered water tables, few studies have evaluated deep‐planting where planting depths must exceed one‐meter to reach water tables and where herbivore protection is required. To evaluate deep‐planting as an irrigation alternative where lowered water tables present a challenge to riparian restoration, we conducted experimental plantings along an incised stream within a semiarid watershed using deep‐planting without supplemental irrigation in combination with several tree shelter designs. Our results indicate deep‐planting cottonwood (Populus trichocarpa) and willow (Salixspp.) pole cuttings in augered holes that penetrated water tables up to 1.9 m below the surface significantly increased the probability of survival, with water table penetration significantly increasing the odds of survival by a factor of 7. Deep‐planting with access to lowered water tables in combination with 0.9‐m vented plastic tree shelters significantly increased the probability of survival, with over 50% higher survival after three years compared to unprotected and 1.‐m circular fence caged plants that were also deep‐planted with access to water. However, taller fence cages significantly reduced the probability of terminal bud loss from browsers with over 25% lower browse rates after three years. Therefore, we conducted additional experimental plantings to evaluate two taller plastic tree shelter designs to maximize survival while minimizing browsing. The results of our study indicate that deep‐planting pole cuttings of cottonwood and willow with access to lowered water tables in combination with taller 1.8‐m vented plastic tree shelters provided statistically similar survival as compared to the shorter 0.9‐m vented plastic tree shelters after two years while significantly reducing browsing by approximately 75% two years after planting.