Annals of Forest Research

Effect of Polyethylene glycol, temperature, and stratification in thirty plant species: Implications for conservation and management

Tue, 31 Dec 2024 00:00:00 +0000

Seed ecology is a fundamental view of a population's regenerative potential and under climate change needs investigation for proper management and conservation of plant populations. In the Mediterranean basin extreme rainfall variability is expected to prevail during the next decades. The aim of the study is to investigate the germination potential of thirty plant species by placing their seeds under gradients of water potentials with the use of polyethylene glycol, a polymer used to mimic water stress in seeds to assess their adaptive potential. We applied three different osmotic potentials (-0.03 MPa , -0.50 MPa, -1.56 MPa) using PEG6000 in seeds from thirty different plant species. Prior PEG treatment seeds grouped to non-stratified and stratified ones at +2°C for 1 month. Seeds were then germinated under either constant +21°C or alternate +25°C/+15°C temperature with 12-hours photoperiod. Germination was affected by PEG level, stratification and temperature which acted either independently or in combination, and the response to those factors was species specific. Most species that PEG had affected their germination, responded positively in water stress at -0.5 MPa and some of them further increased their seed germination under -1.56 MPa. However, in species where PEG had no effect, their germination response was driven by the other two factors either independently or in combination. Finally, there were also species that presented low germination, unaffected by the studied factors. The present study demonstrates the ability of several Mediterranean species to germinate under various levels of water stress and can be applied to species management and conservation strategies.

Long-term persistence of butterfly diversity in a sustainably managed forest ecosystem

Thomas Schmitt, Tobias Hennige, Alexej Maseluk, Jan Christian Habel — Tue, 31 Dec 2024 00:00:00 +0000

In recent decades, intensification in land use has led to severe losses of
biodiversity across major parts of the world. Studies from Central Europe revealed
severe decline of insect diversity across agro-environments, but to a lower extent
in forest ecosystems. Sedentary specialist species are suffering particularly, while
mobile generalist species are much less affected. Numerous species are also
disappearing from nature reserves. On the long run, biodiversity presumably can
only be maintained in ecosystems of sufficient size, but is lost in small and isolated
habitats. In order to test this assumption, we conducted butterfly counts over a
period of 20 years in a large, heterogeneous and sustainably used forest ecosystem
in southern Germany. We found no significant changes in diversity and abundance
over the two decades of study. However, our data revealed a significant shift in
species´ community structure over time, with the proportion of generalist species
increasing and the proportion of specialist species decreasing. These changes are
most likely due to changes in habitat structures. At the beginning of our study,
wind-blows resulting from the heavy storms in the late 1990s represented open
areas, but subsequently reforested in the wake of natural succession. Since these
temporary open habitats had attracted a particularly high number of specialised
species, the observed changes are probably due to these natural processes in a
forest ecosystem. In general, our results show that heterogeneous ecosystems
of large size may preserve a species-rich butterfly community in the long run.

Links between tree phenology and wood traits in sessile oak (Quercus petraea (Matt.) Liebl.)

Tue, 31 Dec 2024 00:00:00 +0000

Tree phenology and wood traits are considered of foremost importance in understanding species’ responses to the influence of climate change, thus the existence of a link between tree phenology and wood traits has become increasingly appealing in forestry research. The aim of this study was to explore the relationship between leaf flushing and wood traits (basic wood density, tree ring width, tree ring phenology, sapwood width and number of sapwood rings) in sessile oak (Quercus petraea (Matt.) Liebl.). We investigated trees with distinctive phenological behaviour (early flushing and late flushing) from three peripheral populations, one non-peripheral population and one sessile oak comparative trial close to the species eastern distribution range in the Eastern Carpathians. Covariance analysis, partial correlations, nonparametric statistics, and Principal Component Analysis were used to investigate the link between tree phenology, wood density, and some structural metrics. It was statistically confirmed that, at comparable ages and radial growth, the sessile oak trees exhibiting late leaf flushing had lighter basic wood density and greater density differences between sapwood and heartwood than early flushing trees. Independent of age, trees with intermediate flushing have wider rings, the formation of which is much earlier than in early flushing trees. At the same age, late trees from geographically peripheral populations have a higher number of sapwood rings. Also, the results revealed that peripheral populations had lower basic wood density, while this was not the case for peripheral provenances tested in the comparative trail established in an ecologically optimal area. These findings help us enlarge our understanding of the relationship between leaf flushing and wood traits, which could be useful for improving sessile oak management strategies near the eastern limit of the sessile oak natural range, which is becoming more and more critical in the context of the current climate changes.

Mean annual temperature mainly drives spatial pattern of plant functional traits in inland arid and semi-arid areas

Tue, 31 Dec 2024 00:00:00 +0000

The distribution pattern of different plant functional traits in arid and semi-arid areas and their environmental impact mechanism are still unclear. The aim of this study is to elucidate the spatial distribution patterns of four key plant functional traits and the effects of environmental factors on their variation in inland arid and semi-arid areas and thus provide a reference for the prediction of species distribution and biodiversity conservation in this region. We focused on wild seed plants naturally distributed in Xinjiang, and by reviewing floras and data sharing platforms, we sorted and compiled the species list and distribution, plant functional traits and environmental data, including 3,953 species information, 44,302 county-level distribution records, 3,892 plant functional traits information and 29 environmental variables. Spatial and statistical analyses were utilized to detect the spatial distribution patterns of four key plant traits in 50 × 50 km grid cells. The spatial variation in different functional traits was explored and environmental drivers were identified. The results showed that there were significant latitudinal and altitudinal gradient patterns of plant functional traits, and there were significant spatial correlations between different traits. Among the three types of environmental factors (climate, soil and habitat heterogeneity), climate factors played the most pronounced role in explaining functional traits. Mean annual temperature (MAT) was the most important driver of the spatial distribution patterns of each trait. Overall, vegetative and reproductive growth of plants is more favorable in areas with higher temperatures, abundant precipitation, fertile soils and high habitat heterogeneity, which is mainly reflected in higher plant height, larger leaves, earlier flowering time and longer flowering duration.

Prioritizing conservation areas based on contributions to rarity and beta diversity in Mediterranean forest ecosystems in Türkiye

Kürşad Özkan, Özdemir Şentürk, Münevver Arslan, Mehmet Güvenç Negiz — Tue, 31 Dec 2024 00:00:00 +0000

The depletion of forest biodiversity arising from insufficient conservation of resources due to wood extraction, overgrazing, fire, and land use presents a significant challenge in the Mediterranean region. It becomes crucial to identify priority conservation areas for safeguarding biodiversity. We used plant species data taken from 800 plots in the Kuyucak mountain district, a typical Mediterranean forest ecosystem in Türkiye and maps of seven potential environmental predictors: elevation, aspect, slope, head index, topographical position index, landform characteristics, and bedrock geology. To assign priority areas for the conservation, local contribution to beta diversity (LCBD) and relative contribution to total rarity (RIRR) were examined with community metrics and environmental predictors, respectively. Correlation results showed that LCBD was positively related to rare species richness but negatively related to common species richness. RIRR was significantly associated with all the community metrics. According to the results of Random Forest regression models, elevation was the most important variable of LCBD, followed by slope, heat index, and pebblestone. For RIRR, the most contributed variables were elevation, heat index, limestone, and slope, respectively. The LCBD and RIRR Random Forest regression models were extrapolated along the Kuyucak mountain district, resulting in the creation of potential distribution maps for both LCBD and RIRR. Subsequently, from these maps, two distinct conservation value maps have been developed for the Kuyucak mountain district based on four conservation priority classes (Priority Class 1, Priority Class 2, Priority Class 3, and Priority Class 4): one employing a conservation cost approach and the other applying an ecology-centered approach. The results suggest that areas with elevated values of both LCBD and RIRR values are primarily situated below 1100 m on steep valley slopes, characterized by the presence of karstic limestone and intricate terrain. Compared to other areas, prioritizing the protection of such areas can provide greater benefits in contributing to ecological uniqueness.

Keywords: Community rarity, Species contributions to beta diversity, Conservation priority, Ecological uniqueness, Indicator species analysis, Machine learning

Comparing efficiency, timing and costs of different walking paths in HMLS LIDAR survey

Tue, 31 Dec 2024 00:00:00 +0000

The technological innovation of terrestrial LIDAR systems has recently given forest planners greater access to key features on forest structure. The Hand Held Mobile Laser Scanner (HMLS) is a recently developed LIDAR tool that is particularly user-friendly and reliable. It is especially useful in the mapping of forest stands, thanks to its implementation of the Simultaneous Location and Mapping Algorithms (SLAM) algorithm. Thus, the present study investigates the ideal walking path to follow during HMLS scanning to survey trees and estimates the biometric parameters of forest stands by testing three distinct schemes. Specifically, two different forest ecosystems are considered in experimental HMLS LIDAR surveys, a beech-dominated deciduous forest and an oak-dominated deciduous forest. Finally, a cost/benefit analysis of each laser survey is analysed according to three walking path models (STAR, GRID, BORDER). A control analysis is also performed of the traditional method without LIDAR. This study contributes to the advancement of a growing body of research on Precision Forestry by considering different characteristics of the forest environment. Regarding practical application, the resulting evaluation of field survey technology can help foresters integrate these techniques into their basic tool kit for forest planning and management processes.

Diallel crossing (10x10) in Swiss stone pine. Juvenile-adult correlations and genetic gain for predicting forward selection

Marius Budeanu, Flaviu Popescu, Emanuel Besliu, Ecaterina Nicoleta Apostol — Tue, 31 Dec 2024 00:00:00 +0000

Swiss stone pine (Pinus cembra) is a viable solution for afforestation in the
high mountain zone, at the upper limit of the forests, due to the species adaptation
ability to the limiting climatic conditions. The aim of this study was to analyse the
genetic variability, inheritance rate and juvenile-adult correlations, in a 26 years
full-sib (10x10 complete mating design) trial, in order to predict the genetic gain of
forward selection. In the spring of 2023, measurements and evaluations were carried
out for all the existing trees, for Survival rate (Sr), growth (Diameter as breast
height- Dbh, Trees’ height- Th, Trees’ volume- Tv) and quality traits (Forks, stem
slenderness- Ss, branches’ diameter- Bd, branches’ finesse- Bf, defoliation- Def).
The 90 cross-pollinated (CP) families registered 50% of Sr whereas the other 10 selfcross-pollinated (consanguineous) registered just 11% of Sr, and the majority of those
trees are dominated and face extinction in the next years. Juvenile-adult correlations
were highly significant (p<0.001), indicating that early selection (at the age of 14
years) might be efficient. At the trial age, based on the medium to high heritabilities,
the forward selection of the best 10% individual trees from the top 20 of the 90 CP
families, for Dbh, could be applied, which ensure at least 9.2% of genetic gain.

The importance of standing deadwood in white-backed woodpecker (Dendrocopos leucotos) habitat from deciduous forests in central Romania

Tue, 31 Dec 2024 00:00:00 +0000

The white-backed woodpecker (Dendrocopos leucotos) is one of the bird species which depends on dead and dying trees as their most important habitat resource. Because of this, it is affected by forest management that removes deadwood and changes the structure of old stands. In Romania, its relations with the structures of forests with and without management, including standing deadwood, are not known. The main objectives of this study were the analysis of the most representative elements of snags in its specific habitat – mainly beech forest in low mountains from central Romania. Based on the presence-absence of species, by applying the standard woodpeckers monitoring protocol using a total of 25 fixed points we compared deadwood variables (snag density, volume, basal area) for the entire study area, regardless of forest structure and management, and for stands over 70 years old, as potentially suitable or optimum habitat for the species. The comparison between plots with and without analysed species shows several significant differences especially regarding the number of snags, volume and basal area mainly for stands older than 70 years. The PCA of the variables for the trees with a DBH > 10 cm explained 74.4% of the variance, but for the very large trees (DBH > 40 cm) this percent is the highest one (89.9%). At the same time, the values of several variables (e.g. snag volume, basal area) are similar or higher than those in various areas of Europe. As a main conclusion, these forests are suitable or optimal for white-backed woodpecker and the Romanian forest management can be considered "closer-to-nature" at least for beech stands but for maintaining and improving the species typical habitat structure a few conservation measures should be applied in addition.

The inevitable role of the oil market: Does its price really matter for forestry investment in China?

Linglan Zhang, Meng Qin, Chi Wei Su — Tue, 31 Dec 2024 00:00:00 +0000

Delving into the intricate roles of oil prices holds the key to attaining sustainable growth of forestry investment in China. Utilising the full- and sub-sample approaches, this article aims to reveal the dynamically evolving relationships between oil price (OP) and forest investment (FI) in China. The quantitative outcomes underscore the complex interplay between OP and FI, highlighting favourable and unfavourable impacts. Notably, the findings indicate that a substantial surge in oil prices could potentially pose obstacles to forestry investment in China, whereas a decline in OP could serve as a stimulus. Nevertheless, it is imperative to acknowledge that this inference is not uniformly applicable when the effect turns positive, primarily influenced by sluggish economic conditions resulting from the global trade wars. Conversely, FI positively influences OP, underscoring that the decline in forestry investment in China could drive down oil prices through psychological and environmental factors. Amid escalating economic and energy uncertainties globally, essential policy suggestions will be proffered to China, aiming to ensure the robust development of the oil market and forestry investment.

Exploring the association between adaptive and growth traits and within-individual genetic diversity in common beech (Fagus sylvatica)

Tue, 31 Dec 2024 00:00:00 +0000

Common beech (Fagus sylvatica L.) is one of Europe's most widespread forest tree species. In the actual context of climate change, this species has responded through its self-regulation mechanisms, proving a high plasticity. It is important to explore the specific mechanisms driving its response to climate change, taking into account silvicultural, phenological, and genetic perspectives and their interaction. Here, we tested for association between adaptive and growth traits and within-individual genetic diversity measured as individual heterozygosity (proportion of heterozygous loci per sampled individual), based on six genomic microsatellite markers (gSSRs, genomic simple sequence repeats) and six expressed sequence tag microsatellites (EST-SSRs) for 55 beech trees. We evaluated the spring and autumn phenology of beech trees sampled along an altitudinal gradient (560 - 1150 m) and the architectural traits using a non-destructive terrestrial laser scanning method (TLS). The effect of stand density at the onset of the growing season was evaluated by quantifying the competition through the Hegyi index. The onset of bud burst and senescence, as well as the length of the growing season, varied significantly and inversely proportionally with the altitudinal gradient. There was a difference of 14 days between the individuals located at the extremities of the altitudinal gradient in the onset of bud burst, 15 days in the onset of senescence, and 30 days in the length of the growing season. We obtained a very significant and positive correlation between altitude and bud burst and a very significant but negative one between altitude and the length of the growing season. An increase in tree competition directly implied a decrease in DBH and crown dimensions, especially by neighbours closer than 4 m. Stem's slenderness significantly increased with higher competition. Our results revealed a positive relationship between individual heterozygosity and the length of the growing season, as well as with the trunk volume and DBH. Higher individual heterozygosity was associated with a longer growing season, and a precocious onset of bud burst in beech. Higher heterozygosity was also associated with considerably higher total tree biomass. The genetic diversity was inversely proportional to stem forking. TLS shows great potential in extracting beech tree biomass indicators, but we still recommend using the conventional method as a complementary method for data validation, although it is time-consuming.

Ecological species groups and interspecific associations of dominant woody species in a seasonal tropical forest of Laos

Tue, 31 Dec 2024 00:00:00 +0000

The study of ecological species groups (ESGs) and interspecific interactions offers important insights into the mechanisms that drive tree species coexistence and enhances our understanding of plant community structure, function, and taxonomy. This study aimed to identify ESGs within a seasonal tropical forest in Phou Khao Khouay National Park, located in central Laos, and to investigate the key environmental factors influencing their distribution. Additionally, the study analysed community stability and interspecific associations among woody species using various statistical techniques, including Variance Ratio (VR), chi-squared tests, Association Coefficients (AC), and percentage of Co-occurrence (PC). To collect data, thirty-two permanent plots, each covering an area of 2500 m² (50 × 50 m), were established. In each plot, floristic data and species abundance were recorded, along with soil samples from two depths (0–10 cm and 10–20 cm) for physicochemical analysis. Vegetation data were classified using Two-Way Indicator Species Analysis (TWINSPAN), and differences between ESGs were evaluated using Analysis of Variance (ANOVA). Indicator Species Analysis (ISA) was applied to identify key species for each ESG, while Canonical Correspondence Analysis (CCA) was employed to explore the relationships between ESGs and environmental variables. The results revealed that the woody plant communities in the study area were relatively stable, exhibiting predominantly positive interspecific associations. Additionally, the distribution of the fosur identified ESGs showed a strong correlation with topographical factors – such as elevation, aspect, and slope – and soil properties, including pH, organic matter content, cation exchange capacity, total nitrogen, phosphorus, potassium, and soil texture. These findings underscore the importance of recognizing microhabitats that support the growth and conservation of woody plant species in Phou Khao Khouay National Park, offering valuable insights for future ecological research and conservation initiatives.

Tradeoffs and limitations in determining tree characteristics using 3D pointclouds from terrestrial laser scanning: A comparison of reconstruction algorithms on European bech (Fagus sylvatica L.) trees

Sergiu Constantin Florea, Ioan Dutca, Mihai Daniel Nita — Tue, 31 Dec 2024 00:00:00 +0000

Terrestrial laser scanning (TLS) has quickly gained momentum in forestry as a fast and nondestructive alternative to determine tree shape and volume. Determining tree shape and volume is fundamental for a wide range of forestry applications, including the estimation of carbon stock and development of volume and biomass allometric models. However, tree shape and volume are often determined from TLS data based on different available algorithms, with direct implications on the measured tree feature. In this study we compared several algorithms for tree reconstruction from TLS data, with respect to their capacity to accurately determine tree characteristics such as diameter at breast height (DBH), tree height (H), stem volume (Vst) and total aboveground tree volume (Vtot). The following algorithms were compared using Bland-Altman limits of agreement (LoA): (i) TreeQSM, (ii) 3D Forest, (iii) RANSAC and (iv) Poisson. The data used for the comparison was collected from 10 sample plots, totalizing 40 European beech (Fagus sylvatica L.) trees, covering a DBH range from 6.2 cm to 76.0 cm and H range from 9.5 m to 36.2 m. The results showed that the algorithm used to analyse the TLS data affected notably the tree characteristics. The LoA were up to 3.65 m􀀀 for Vtot, up to 7.5 cm for DBH and up to 1.1 m for H, suggesting a rather weak agreement between algorithms. From our comparison, TreeQSM emerged as the most reliable algorithm for comprehensive trait reconstruction, while Poisson was well suited for stem volume estimation. Moreover, determining H seems to be less affected by the algorithm selection compared to DBH. Our findings raise awareness about algorithm selection in TLS data processing and highlight the importance of selecting an appropriate algorithm to meet the specific objective when using TLS to determine tree shape and volume.

Investigation of the effects of tree species on air quality using i-Tree software: A case study in California

Zeynep Cansu Ayturan, Cezar Kongoli, Fatma Kunt — Tue, 31 Dec 2024 00:00:00 +0000

The USDA Forest Service has developed a unique software and tree modelling suite called i-Tree. Several of its instruments are capable of exploring the benefits of trees and forests for pollution mitigation, reduction of storm water runoff, carbon sequestration and storage. However, the system remains underutilized for investigating the effects of trees on air quality. In this study, counties in California (CA), United States, were selected using the i-Tree Landscape tool. Next, several characteristics including land cover details, forest details, population, air quality, carbon sequestration capacity, and air pollution removal capacity, were investigated. When considering the air quality situation in these counties, O3 and PM2.5 are the primary pollutants. The planting prioritization map of California was created based on population density, tree cover, plantable space, average PM2.5 and O3 concentration values, and the counties with the highest planting priority were selected using i-Tree Planting tool. Using this instrument, a case study on the modelling of the removal performances of these air pollutants by multiple new species (Turkey oak, Siberian elm, European hackberry, European white elm, Common ash, European silver birch, Velvet ash, Black alder, Bigleaf linden) in priority areas was conducted. The most effective modelled tree species in the area was found to be Turkey oak for its effects in improving air quality in general and O3 in particular. When compared to the effects of modelled trees, the effects of the existing public trees in California were determined to have a comparatively minor impact.