Forests

Wang, Hui;He, Mengyu;Ran, Nan;Xie, Dong;Wang, Qiang;Teng, Mingjun;Wang, Pengcheng

doi: 10.3390/f12010101pmid: N/A

Forest ecosystems are in serious trouble globally, largely due to the over-exploitation. To alleviate environmental problems caused by deforestation, China has undertaken a series of key forestry ecological development programs, including the Natural Forest Protection Program (NFPP), the Conversion of Cropland into Forests Program (CCFP), the Desertification Combating Program around Beijing and Tianjing (DCBT), the Key Shelterbelt Development Programs in the Three-North Region and in the Middle and Lower Reaches of the Yangtze River (KSDP) and the Nature Reserve Development Program in Forestry Sector (WCNR). This article aims to make a documentation of the specific contents (duration, major aims, geographic coverage and investment), and environmental impacts of these programs from peer-reviewed literature, official reports and journals. Environmental impact is measured with land area afforested (except the WCNR) and the consequent changes in ecosystem function. Overall, with the huge investment and long-term efforts, these programs have made tremendous progress in increasing vegetative coverage, enhancing carbon sequestration, controlling soil erosion, conservation of biodiversity, etc. For proper implementation and remarkable achievement, a more balanced approach with flexible planning, suitable measures and proper management should be adopted. Meanwhile, the scientific communities need to be more actively involved in execution and assessment of these programs. The environmental impact of the DCBT, the KSDP, and the WCNR deserve more research concern.

Gülçin, Derya;van den Bosch, Cecil C. Konijnendijk

doi: 10.3390/f12010062pmid: N/A

The biomass represented by urban trees is important for urban decision-makers, green space planners, and managers seeking to optimize urban ecosystem services. Carbon storage by urban trees is one of these services. Suitable methods for assessing carbon storage by urban trees are being explored. The latest technologies in remote sensing and data analyses can reduce data collection costs while improving accuracy. This paper introduces an assessment approach that combines ground measurements with unmanned aerial vehicle-based light detection and ranging (LiDAR) data to estimate carbon storage by urban trees. Methods underpinning the approach were tested for the case of the Vancouver campus of the University of British Columbia (UBC), Canada. The study objectives were (1) to test five automated individual tree detection (AITD) algorithms and select one on the basis of the highest segmentation accuracy, (2) to develop a model to estimate the diameter at breast height (DBH), and (3) to estimate and map carbon storage over the UBC campus using LiDAR heights, estimated DBHs, and an existing tree-level above-ground carbon estimation model. Of the segmentation algorithms tested, the Dalponte AITD had the highest F score of 0.83. Of the five CW thresholds (th) tested in the DBH estimation model, we chose one resulting in the lowest Akaike’s information criterion, the highest log-likelihood, and the lowest root-mean-squared error (19.55 cm). Above-ground carbon was estimated for each tree in the study area and subsequently summarized, resulting in an estimated 5.27 kg C·m−2 over the main campus of UBC, Vancouver. The approach could be used in other urban jurisdictions to obtain essential information on urban carbon storage in support of urban landscape governance, planning, and management.

Tognetti, Roberto;Marshall, John D.

doi: 10.3390/f12010068pmid: N/A

Although aspects of forest ecophysiology and forest environments have received considerable attention from research scientists in the last three decades, assessment of implications for meeting the climate targets and international agreements is still a matter of debate [...]

Vivas, María;Hernández, Jerónimo;Corcobado, Tamara;Cubera, Elena;Solla, Alejandro

doi: 10.3390/f12010100pmid: N/A

The maternal environment of a tree species can influence the development and resistance of its offspring. Transgenerational induction of resistance is well known in plants but its occurrence in forest tree species has been less reported. Quercus ilex L. (holm oak) is a widespread Mediterranean tree species threatened by the invasive Phytophthora cinnamomi Rands pathogen. The influence of P. cinnamomi on the offspring of infected Q. ilex mother trees has not been studied. This study compared the performance and tolerance to P. cinnamomi of seedlings from non-infected and P. cinnamomi-infected trees. Acorns from Q. ilex trees were collected from five forests. After isolations were conducted in the rhizosphere of several trees, in each forest, three trees were selected as non-infected and three were selected as P. cinnamomi-infected. Forty acorns per tree were weighed and sown under greenhouse conditions, and when plants were aged ~9 months they were challenged with P. cinnamomi. Plant mortality was higher in the offspring of non-infected trees than in the offspring of P. cinnamomi-infected trees (26.2% vs. 21.1%, respectively). Consistently, survival probabilities of seedlings from P. cinnamomi-infected trees were higher than those of seedlings from non-infected trees, particularly in seedlings with reduced growth. Although acorns from healthy Q. ilex trees were heavier than acorns from P. cinnamomi-infected trees, the time to death of inoculated seedlings was not influenced by seed weight. The time to death of seedlings was positively related to belowground mass, particularly to an increased proportion of fine secondary roots. We report transgenerational-induced resistance to P. cinnamomi in Q. ilex triggered by an unknown mechanism independent of acorn mass. Information about the persistence of transgenerational effects in Q. ilex offspring and the influence of these effects on plant fitness is crucial to improve the management and regeneration of this declining species.

Pramreiter, Maximilian;Stadlmann, Alexander;Huber, Christian;Konnerth, Johannes;Halbauer, Peter;Baumann, Georg;Müller, Ulrich

doi: 10.3390/f12010087pmid: N/A

The development of high-performance, veneer-based wood composites is a topic of increasing importance due to the high design flexibility and the comparable mechanical performance to solid wood. Part of this improved mechanical performance can be contributed to the size effect present in wood. Based on previous findings in the literature, this size effect can be either strengthening or weakening. The presented study investigates the influence of thickness and load angle on the tensile strength and tensile stiffness of peeled veneers compared to thin sawn timber. Veneers with thicknesses of 0.5 ± 0.05 mm, 1.0 ± 0.05 mm and 1.5 ± 0.05 mm as well as sawn wood with thicknesses of 1.5 ± 0.1 mm, 3.0 ± 0.1 mm and 5.0 ± 0.1 mm were tested in tension under different load angles (0°, 45° and 90°). The results only partly confirm a size effect for strength parallel to the grain. The strength perpendicular to the grain increased significantly between 0.5 mm and 1.5 mm, with a significant decrease between 1.5 mm and 5.0 mm. The presence of lathe checks diminished the strength perpendicular to the grain of the veneers by about 70% compared to solid wood, partly overshadowing a possible strengthening effect. It was concluded that a transition from a strengthening to a weakening behaviour lies in the range of multiple millimetres, but further investigations are needed to quantify this zone more precisely. The presented results provide a useful basis for the development of veneer-based wood composites with a performance driven layer-thickness.

Cruzado-Vargas, Ana Laura;Blanco-García, Arnulfo;Lindig-Cisneros, Roberto;Gómez-Romero, Mariela;Lopez-Toledo, Leonel;de la Barrera, Erick;Sáenz-Romero, Cuauhtémoc

doi: 10.3390/f12010069pmid: N/A

Research Highlights: Reciprocal altitudinal transplants of Abies religiosa seedlings within the Monarch Butterfly Biosphere Reserve (MBBR) allow prediction of the impacts of climatic change, because they grow in sites with a climate that differs from that of their origin. Background and Objectives: Climatic change is generating a mismatch between the sites currently occupied by forest populations and the climate to which they have adapted. This study determined the effect on the survival and growth of A. religiosa seedlings of transfer to sites that were warmer or colder than that of the origin of their seeds. Materials and Methods: Eleven provenances of A. religiosa, collected along an altitudinal gradient (3000 to 3550 m a.s.l.), were assayed in common gardens in three sites of contrasting altitude: 3400, 3000 and 2600 m a.s.l. The results were evaluated by fitting a response curve with a mixed model. Results: The climate transfer distance for the seasonal balance between the temperature conducive to growth (degree days above 5 °C) and the available precipitation (a ratio expressed as dryness index) dominated the shape of the response function curve. The rainy season (June–October) dryness index transfer distance was critical for survival, while that of the cold and dry season (November–February) was critical for aerial biomass, and the annual index was critical for the increase in basal diameter. The effect of climatic transfer distance is much more negative (triggering about 45% mortality) when transfer is toward warmer and dryer sites (at 400 m lower in altitude, +1.9 °C warmer and 16% less precipitation), than when shifting toward colder and wetter sites (400 m higher in altitude, resulting in 95% survival). Conclusions: The projected higher temperatures and lower precipitation due to climatic change will undoubtedly cause severe mortality in young A. religiosa seedlings. A 400 m shift upwards in altitude to compensate for climatic change (assisted migration) appears to be a feasible management action.

Longépée, Esméralda;Ahmed Abdallah, Anliati;Jeanson, Matthieu;Golléty, Claire

doi: 10.3390/f12010053pmid: N/A

The majority of studies on local ecological knowledge (LEK) relate to communities or groups relying on ecosystem(s) for their livelihood. In our case study, Mayotte Island, a French overseas department, very few people rely on mangrove ecosystem for natural resources but most of them are attached to it because of leisure activities and beliefs. The questions on mangrove LEK generally deal with a single aspect of ecological knowledge of surveyed people and is mixed with other information such as harvesting practices, anthropogenic impacts, and management issues. The aim of our study is to better understand the level of ecological knowledge of surveyed inhabitants of Mayotte and to assess whether factors linked to the profile of respondents have an influence on it. For this purpose, we carried out two main survey campaigns in three villages fringing two stable mangroves of Mayotte: the first one consisted of qualitative interviews and the second one, questionnaires lending quantitative results. Cross tabulations and Chi square tests of independence were carried out to determine the link between LEK and influencing factors. Results show that some LEK implying localized observation, such as the identification of mangrove trees and the knowledge of the coastal protection role of the mangrove, are well shared by surveyed people whereas others, such as the number and the name of mangrove tree species, are poorly known. The results also highlight the difficulty of questions implying observation at the landscape level and interpretation of observation. All the influencing factors selected have a significant influence on, at least, one LEK variable. The results highlight differences in LEK of villages bordering two nearby mangroves calling for a local management of these systems.

Galveias, Ana;Costa, Ana R.;Bortoli, Daniele;Alpizar-Jara, Russell;Salgado, Rui;Costa, Maria João;Antunes, Célia M.

doi: 10.3390/f12010064pmid: N/A

Research Highlights: Daily airborne Cupressaceae pollen disruption ranged from 20 to 90%; relative humidity (RH), rainfall and atmospheric pressure (AtP) were the major meteorological determinants of this phenomenon. Background and Objectives: Cupressaceae family includes several species that are widely used as ornamental plants pollinating in late winter-early spring and might be responsible for allergic outbreaks. Cupressaceae pollen disruption may favour allergen dissemination, potentiating its allergenicity. The aim of this work was to characterize the Cupressaceae pollen aerobiology in Évora, South of Portugal, in 2017 and 2018, particularly the pollen disruption, and to identify the meteorological parameters contributing to this phenomenon. Materials and Methods: Pollen was collected using a Hirst type 7-day pollen trap and was identified following the standard methodology. Temperature, RH, rainfall, global solar radiation (Global Srad), AtP, wind speed and direction were obtained from a weather station installed side-by-side to the Hirst platform. Back trajectories (12-h) of air masses arriving at Évora were calculated using the HYSPLIT model. Results: Cupressaceae pollen index was higher in 2017 compared to 2018 (>5994 and 3175 pollen/m3, respectively) and 36 ± 19% (2017) and 64 ± 17% (2018) of the pollen was disrupted. Higher levels of disrupted pollen coincided with RH > 60% and rainfall. Temperature, Global Srad and AtP correlated negatively with pollen disruption. Wind speed and wind direction did not significantly correlate with pollen disruption. Intra-diurnal pollen pattern peaked between 9:00 am–2:00 pm, suggesting local origin, confirmed by the back trajectory analysis. Intra-diurnal pollen disruption profile followed hourly pollen pattern and it negatively correlated with AtP, temperature and Global Srad but was uncorrelated with RH. Conclusions: The results suggest that RH, rainfall and AtP are the main factors affecting airborne Cupressaceae pollen integrity and in conjunction with daily pollen concentration may be used to predict the risk of allergy outbreaks to this pollen type.

Muscolo, Adele;Settineri, Giovanna;Romeo, Federico;Mallamaci, Carmelo

doi: 10.3390/f12010108pmid: N/A

Forest soil biodiversity, which drives natural ecosystem multifunctionality, can be altered by incorrect forestry management practices. Pinus laricio is the most representative and widespread conifer species in Calabria, South Italy, and appropriate management is needed to maintain Pinus laricio forest for its great economic and natural value. In Europe, thinning is considered the most effective silvicultural treatment to maintain/increase the ecological value of coniferous stands. In this study, moderate thinning (MT), intense thinning (HT), and clear cut (CC) treatments were used to manage Pinus laricio stands with the aim of identifying the thinning intensity that is less detrimental to soil biodiversity. The effects of the different thinning intensities were evaluated, in two contrasting seasons (summer and winter), on the abundance, and diversity of arthropods, fungi, and bacteria colonies as well as on selected soil properties (organic matter, humification index, bulk density, pH) related to soil habitability. Results evidenced that the abundance, species richness, and diversity of arthropods, as well as fungi, bacteria colonies, and soil properties, changed with the treatments and seasons. Under HT, the greatest biodiversity and the highest amounts of arthropods, fungi, and bacteria were found in both seasons. This study finds evidence for Connell’s intermediate disturbance hypothesis, highlighting that the greatest organic carbon content and humification index, as well as the lowest bulk density, found in HT reduced the likelihood of competitive exclusion between occurring species, thereby promoting high species richness and diversity. This study gives insights into ecological relationships between understory composition related to tree species abundance and soil community.

Taghiyari, Hamid R.;Majidi, Roya;Arsalan, Mahnaz Ghezel;Moradiyan, Asaad;Militz, Holger;Ntalos, George;Papadopoulos, Antonios N.

doi: 10.3390/f12010063pmid: N/A

The penetration properties of three different liquids on the surface of medium-density fiberboard (MDF) and particleboard panels were studied. Water, as a polar liquid, was compared to two other less polar liquids (namely, ethanol and kerosene) with significantly larger molecules. Measurement of penetration time and wetted area demonstrated significantly higher values for water in comparison with the other two liquids, in both composite types. Calculation of adsorption energies, as well as adsorption distances, of the three liquid molecules on hemicellulose showed higher potentiality of water molecules in forming bonds on hemicellulose. However, comparison of the adsorption energies of cellulose with hemicellulose indicated a higher impact of the formation of bonds between hydroxyl groups in water and cellulose in hindering the penetration of water molecules into the composite textures. It was concluded that the formation of strong and stable bonds between the hydroxyl groups in water and cellulose resulted in a significant increase in penetration time and wetted area.