Adult Trees Research Articles

The effects of environmental heterogeneity on the morphological similarity of toothed-leafed red oak species (Acutifoliae; <i>Quercus</i>) in Mexico and Central America

Background: In plants, environmental gradients can promote similar morphophysiological traits in species that inhabit areas with similar climatic conditions. Here, to evaluate possible causes of morphological similarity, we analyzed leaf morphological and functional variation in toothed-leaf oaks and its relationships with environmental and geographic variables. Hypotheses: We expected that species with a greater degree of environmental overlap would exhibit similar leaf morphology, and those with a broader range of environmental tolerance would exhibit greater leaf morphological variation. Studied species: Acutifoliae group (Fagaceae, Quercus) Study sites and dates: Leaf samples were collected from adult trees distributed in diverse forest types between 495 and 2,566 meters above sea level (m asl) in Mexico and Guatemala. Methods: We compared patterns of leaf variation in a total of 2,934 leaves from 640 individuals corresponding to 68 populations of ten oak species using univariate and multivariate analyses. We also characterized the environmental conditions where each of the species occurred using the available geographical records and bioclimatic variables. Results: We found morphological overlap in leaf traits in oak species occurring in similar climatic environments. Additionally, oak species with a greater range of environmental distributions showed greater leaf shape morphological variation. Conclusions: The environment influenced the generation of similar leaf morphologies among oak species despite geographical distance and phylogenetic relationships.

Potential Identification of Root System Architecture Using GPR for Tree Translocation as a Sustainable Forestry Task: A Case Study of the Wild Service Tree

Sustainable economic development serves society but requires taking over space, often at the expense of areas occupied by single trees or even parts of forest areas. Techniques for transplanting adult trees used in various conflict situations at the interface of economy and nature work as a tool for sustainable management of urbanized and industrial areas, as well as, in certain circumstances, forest or naturally valuable areas. This study aimed to evaluate the effectiveness of ground-penetrating radar (GPR) in determining the horizontal and vertical extent of tree root systems before transplantation. Employing this non-invasive method to map root system architecture aids in the appropriate equipment selection and helps define the dimensions and depth of trenches to minimize root damage during excavation. This study specifically focused on the root systems of wild service trees (Sorbus torminalis (L.) Crantz) found in a limestone mine area, where some specimens were planned to be transplanted, as the species is protected under law in Poland. The root systems were scanned with a ground-penetrating radar equipped with a 750 MHz antenna. Then, the root balls were dug out, and the root parameters and other dendrometric parameters were measured. The GPR survey and manual root analyses provided rich comparative graphic material. The number of the main roots detected by the GPR was comparable to those inventoried after extracting the stump. The research was carried out in problematic soil, causing non-standard deformations of the root systems. Especially in such conditions, identifying unusually arranged roots using the GPR method is valuable because it helps in a detailed planning of the transplanting process, minimizing root breakage during the activities carried out, which increases the survival chances of the transplanted tree in a new location.

Climate change and exotic pathogens shift carbon allocation in Mediterranean mixed forests

Abstract Forecasting the effects of global change drivers on ecosystems is one of the most pressing challenges for scientists worldwide. Particularly, climate change and exotic pathogens might have a large impact on plant community dynamics and ecosystem functioning through changes in carbon uptake and sinks. Nevertheless, we still have a poor understanding of the combined effects of these two drivers on plant communities. Here, we explored the impact of rainfall reduction and exotic pathogens on the carbon balance of Mediterranean tree species. For this, we performed a 3‐year field experiment taking advantage of rainfall exclusion infrastructures (30% exclusion) installed in the southernmost European oak forests invaded by the aggressive exotic pathogen Phytophthora cinnamomi. We measured a set of 10 variables representative of tree carbon sources (photosynthetic rates) and sinks (primary production, reproduction, defence, and reserves) in adult trees of three species in two forest types: closed forests of Quercus suber and Q. canariensis, and open woodlands of Q. suber and Olea europaea. We found a large variability in the sensitivity of the different carbon sources and sinks to the effects of drought and pathogens, from variables highly sensitive to both factors (carbon fixation and reproduction, root chemistry) to variables only responsive to drought (litter production) or totally unresponsive (tree trunk, leaf chemistry). Although negative effects predominated, positive effects of rainfall exclusion were also detected in wet years, likely due to a reduction of pathogen abundance in drier soil. Trade‐offs between carbon sinks appeared in all tree species, but rainfall exclusion only modified trade‐offs in Q. suber, the species most susceptible to P. cinnamomi. Synthesis. We provide evidence on the complexity of the combined effects of abiotic (drought) and biotic (pathogens) global change drivers on carbon source and sinks of adult trees, including both negative direct effects and positive indirect effects. Our results showed that these effects varied among co‐existing species, particularly for carbon sinks directly related to tree demography (reproduction). Therefore, long‐term changes in the structure of Mediterranean mixed forests might be expected towards the dominance of species highly resistant to both drought and pathogens.

Contrasted agronomical and physiological responses of five Coffea arabica genotypes under soil water deficit in field conditions.

Breeding programs have developed high-yielding Coffea arabica F1-hybrids as an adaptation against adverse conditions associated with climate change. However, theresponse to drought of coffee F1 hybrids has seldom been assessed. A trial was established with five C. arabica genotypes (2 pure lines: Catimor and Marsellesa and 3 F1 hybrids: Starmaya, Centroamericano and Mundo Maya) planted under the leguminous tree species Leuceana leucocephala. Coffee growth, yield and physiological responses were assessed under a rain-fed (control: CON) and a rainfall reduction treatment (RR) for 2 years. The RR treatment created a long-term rainfall deficit in a region with suboptimal temperature similar to those predicted by climate change scenarios. Moreover, the RR treatment reduced soil water content by 14% over 2 successive years of production and increased hydric stress of the three F1-hybrids (leaf water potentials averaged -0.8 MPa under RR compared with -0.4 MPa under CON). Under RR, coffee yields were reduced from 16 to 75% compared to CON. Mundo Maya F1 hybrid was the sole high-yielding genotype apable of sustaining its yield under RR conditions. Our results suggested that its significant increase in fine root density (CON = 300 and RR = 910 root.m-2) and its maintenance of photosynthetic rate (2.5 - 3.5 mmol CO2 m-2 s-1) at high evaporative demand might explain why this genotype maintained high yield under RR condition. This work highlights a possible drought tolerance mechanism in fruit bearing adult coffee trees where the plant fine root number increases to intake more water in order to preserve turgor and sustainphotosynthesis at high ETo and therefore conserves high yield in dry conditions.

Endemic Prunus species in the high Himalayas, Eastern Nepal, seeking conservation

Prunus species play an important role in preserving the Nepal's unique identity; such as three endemic species of Prunus, Prunus topkegolensis, Prunus jajarkotensis, and Prunus taplejungnica, represent the country's local area. An ecological and social survey of P. topkegolensis and P. taplejungnica was conducted. To analyze these species' regeneration status and population structures, the density of seedlings, saplings, and adult trees were compared, and created a diameter size class diagram. The Wilcoxon signed-rank test was used to compare the average values of seedlings, saplings, and adult trees between two species. To determine the ethnobotanical importance of a species, the relative frequency of citation (RFC) was calculated for various use categories. We classified both species as trees as the average diameter at breast height (DBH) of P. topkegolensis was 19.55 ± 14.66 cm with an average height 5.05 ± 2.28 m, while that of P. taplejungnica was 14.5 ± 7.93 cm with an average height of 4.89 ± 1.66 m. P. topkegolensis had an average 32 ± 31 adult trees, 16 ± 15 saplings, and 21 ± 18 seedlings per 0.1 ha, while P. taplejungnica had 12 ± 5 adult trees, 2 saplings, and 6 ± 4 seedlings per 0.1 ha. The number of seedlings and saplings at the plot level differed significantly between species (W = 75.5, p- = 0.05, and W = 84, p = 0.01, respectively). Both had humped-shaped diameter at breast height size class distribution. However, P. taplejungnica had a more apparent hump-shaped diameter at breast height distribution than P. topkegolensis, indicating that P. taplejungnica has more unsustainable regeneration issues. P. taplejungnica was locally recognized as a separate species from P. rufa, whereas P. topkegolensis was not. P. topkegolensis have seven different use categories, with wood and fuel wood being the most frequently cited, with RFC value 1. Rapid vulnerability assessment (RVA) showed both species are having high conservation threats. In situ conservation measures are suggested to address the issue of poor regeneration and disturbances.

Mycorrhizal Types Regulate Tree Spatial Associations in Temperate Forests: Ectomycorrhizal Trees Might Favour Species Coexistence.

In temperate mixed forests, dominant ectomycorrhizal (EM) tree species usually coexist with diverse arbuscular mycorrhizal (AM) understorey tree species. Here, we investigated the spatial associations between AM and EM trees in two > 20 ha temperate forest mega-plots to better understand the observed 'EM-dominant versus AM-diverse' coexistence. Overall, we found that positive spatial associations (e.g., facilitation) were mostly related to EM trees, while negative spatial associations (e.g., inhibition) were mainly related to AM trees. Because adult EM trees tended to facilitate surrounding AM and EM saplings and other EM adults in these two forests, facilitation hotspots that stabilize AM-EM tree coexistence should be centred around EM tree species rather than around AM tree species. Together, we propose a novel EM-stabilization mechanism, which emphasises how, despite some species-specific variation, EM tree species foster 'EM-dominant versus AM-diverse' coexistence in temperate mixed forests by facilitating other trees.

Conservation genomic study of Hopea hainanensis (Dipterocarpaceae), an endangered tree with extremely small populations on Hainan Island, China.

Hopea hainanensis Merrill & Chun is considered a keystone and indicator species in the tropical lowland rainforests of Hainan Island. Owing to its high-quality timber, H. hainanensis has been heavily exploited, leading to its classification as a first-class national protected plant in China and a plant species with extremely small populations (PSESPs). This study analyzed genome-wide single nucleotide polymorphisms obtained through restriction site-associated DNA sequencing from 78 adult trees across 10 H. hainanensis populations on Hainan Island. The nucleotide diversity of the sampled populations ranged from 0.00096 to 0.00138, which is lower than that observed in several other PSESPs and endangered tree species. Bayesian unsupervised clustering, principal component analysis, and neighbor-joining tree reconstruction identified three to five genetic clusters in H. hainanensis, most of which were geographically widespread and shared by multiple populations. Demographic history analysis based on pooled samples indicated that the decline in the H. hainanensis population began approximately 20,000 years ago, starting from an ancestral population size of approximately 10,000 individuals. The reduction in population size accelerated approximately 4,000 years ago and has continued to the present, resulting in a severely reduced population on Hainan Island. Intensified genetic drift in small and isolated H. hainanensis populations may contribute to moderate differentiation between some of them, as revealed by pairwise F st. In conclusion, our conservation genomic study confirms a severe population decline and an extremely low level of nucleotide variation in H. hainanensis on Hainan Island. These findings provide critical insights for the sustainable management and genetic restoration of H. hainanensis on Hainan Island.

Productivity and Vigor Dynamics in a Comparative Trial of Hedgerow Olive Cultivars

The hedgerow growing system is prevalent in new olive orchards worldwide due to its fully mechanized harvesting. Several works have been published to compare cultivars planted in this system, focusing on productivity and oil composition. However, little research has been conducted on the long-term evaluation of cultivars’ growth habits when trained in hedgerow systems and on how it affects their interannual productivity. In this work, we report the canopy growth habit, productivity, and their correlation for the ‘Arbequina’, ‘Arbosana’, ‘Koroneiki’, ‘Lecciana’, ‘Oliana’, and ‘Sikitita’ cultivars grown in a hedgerow system in Extremadura, central-western Spain, for 9 years. ‘Koroneiki’, ‘Arbequina’, and ‘Lecciana’ were the cultivars with the highest canopy growth, both in young and adult trees, and the ones with the highest pruning needs from 5 to 10 years after planting. The yield behavior in each of the years evaluated was stable in all cultivars except ‘Lecciana’. This alternate bearing was associated with the distribution of total yearly produced biomass between fruits and vegetative growth. ‘Oliana’, ‘Arbosana’, and ‘Sikitita’ were the cultivars with the highest proportion of fruit of the total biomass, and ‘Lecciana’ showed the lowest. This study indicates that cultivars with higher fruit proportions of total biomass might have better suitability for long-term growing in hedgerow formation, fewer pruning needs, and more stable productivity across the years. In this sense, in the climatic conditions considered here, ‘Arbosana’, ‘Sikitita’, and ‘Oliana’ could be the most suitable cultivars for this growing system.

Impacts of spatiotemporal urban expansion on the species richness and functional traits of adults and sapling woody trees and shrubs of urban remnant forest patches

Remnant urban forests, or scattered patches of forest within urban areas, serve as crucial biodiversity reservoirs. Investigating how urban environments influence biodiversity within these forests is essential for enhancing conservation strategies. This study examined data from 15 remnant forest patches in Guiyang, China, to assess the impacts of spatiotemporal urban expansion on species richness and functional traits across different life forms and ontogenetic stages in both interior and edge habitats of these patches. Employing generalized linear regression models, we examined variables including the intensity of urban expansion, road density, type of expansion, compound terrain complexity, and the interplay between urbanization levels and the timeframe of urban development. Our results indicated that increased urban expansion intensity positively affected the species richness of shrubs, yet negatively influenced tree richness. Furthermore, high urbanization levels were associated with lower species richness in adult trees and the species in the sapling and shrub layers with high seed mass traits when the duration of urbanization was prolonged. Additionally, we observed that edge-expansion type urban growth notably increased the risk of losing species with resource-conservation traits compared to leapfrog growth patterns. These outcomes highlight the detrimental effects of intensive urban expansion and edge-expansion growth on the conservation of woody plants, especially those characterized by resource conservation traits. They also draw attention to the delayed impacts of urbanization on plant diversity. In response, we advocate for the reduction of urban expansion intensity and control over edge-expansion growth patterns to protect plant diversity in remnant forests. It is also critical to prioritize the conservation of remnant forest patches located in areas that have undergone extensive urbanization for prolonged periods, as these are particularly vulnerable to biodiversity loss.

Does seasonal flowering and fruiting patterns of cacao only depend on climatic factors? The case study of mixed genotype populations in Côte d'Ivoire

Theobroma cacao, a tropical cauliflorous fruit tree, typically produces flowers and fruits twice a year and exhibits alternate harvesting patterns over consecutive six-monthly seasons in regions with bi-modal rainfall distribution, such as Côte d'Ivoire. This study investigated seasonal variations in flowering and fruiting among trees in populations of mixed cacao genotypes. The intensities of crown and trunk flowering and pod production were monitored for eight consecutive six-monthly seasons on 114 adult cacao trees grown from seedlings. We investigated distributions of seasonal flowering and fruiting values, relationships between flowering and pod production, and the effects of seasonal cumulative rainfall. The patterns of seasonal flowering and fruiting series were analyzed using two descriptors: the first distinguishing between regular and variable patterns, and the second analyzing the structure of such variability, classifying it as either irregular or alternating. Despite being subjected to similar climate and agronomic management, individual trees exhibited highly variable flowering and fruiting behaviors within each season, as well as variable patterns of flowering and fruiting across seasons. Seasonal alternate fruiting on a population scale masked highly variable patterns among trees, and only 19 % of the trees exhibited marked alternate fruiting patterns. Variations in pod production on a tree scale were mainly related to variations in trunk flowering. Endogenous factors seemed to control seasonal variations in flowering and fruiting, even though exogenous factors, both climatic and agronomic, could structure flowering and fruiting patterns at the orchard scale.

Flowering and fruiting of Parkia biglobosa (Jacq.) Benth according to agro climatic zones and land use system in Souhtern Mali

Flowering and fruiting of Parkia biglobosa were monitored along the north–south climatic gradient in Mali. Three sites (Somasso, Zanzoni and Diou) were concerned. Adult trees were monitored in field and fallow stands. Significant variations of flowering and fruiting were observed according to site and stand. The onset of phenological events started earlier in the south and progressed toward the north. Four to five months of flowering and three to four months of fruiting were observed in all sites. The trend of flowering and fruiting was similar for fields and fallows. The difference between sites like that between stands was not significant for the length of flowering and of fruiting. The number of flowering trees varied according to year and stand in all sites. At Somasso 100% of trees in the fallow stand flowered all years, while in the field stand, it fluctuated from 93% in 2019 and 2020 to 100% in 2021. At Zanzoni, 100% of trees in field stand flowered all years, while in the fallow stands it fluctuated from 93% in 2019 and 2021 to 73% in 2020. At Diou, 60% of trees in the fallow stand flowered all years, while in the fields it fluctuated from 73% in 2019 and 2020 to 77% in 2021. The trend of fruiting was similar to that of flowering. The results indicate that phenological events of P. biglobosa are controlled by an intrinsic force and they can be influenced by other factors, such as management practices.

Spatial distribution of the ethnomedicinal plant Aglaonema simplex at the Sakaerat Environmental Research Station, Northeastern Thailand

Abstract. O-thong N, Tasen W, Marod D, Thinkampheang S, Phumphuang W. 2024. Spatial distribution of the ethnomedicinal plant Aglaonema simplex at the Sakaerat Environmental Research Station, Northeastern Thailand. Biodiversitas 25: 3043-3050. Aglaonema simplex Blume (Araceae) is an evergreen herbaceous plant used ornamentally and in traditional medicine. Although the usefulness of this plant has been widely studied and reported, its ecology remains poorly understood. In this study, we examined the effects of various environmental factors on the spatial distribution of A. simplex in a Dry Evergreen Forest (DEF) at the Sakaerat Environmental Research Station (SERS) in Northeastern Thailand. All individual plants were counted; their positions were recorded within a 16-ha Forest Dynamics Plot (FDP), and their distribution pattern was analyzed using Ripley's K function. The spatial distribution of A. simplex was determined using a generalized linear model that incorporated plant density and topographic and edaphic variables within the 16-ha study plot. We found a total of 11,232 A. simplex individuals with a density of 702 individuals ha-1, with a clumped distribution pattern. The modeling results showed that the spatial distribution of A. simplex was positively influenced by soil clay content, soil pH, exchangeable magnesium, and adult tree density; it was negatively influenced by sapling density and rocky outcrops. These findings contribute to the broader understanding of the ecological niche of A. simplex. They can be used to design integrated land management approaches that balance ecological conservation with economic development goals.

Advancements in the techniques for rescue and vegetative propagation of adult Mimosa caesalpiniifolia Benth. trees

ABSTRACT This study focused on the method known as air layering to facilitate the growth of new plants from Mimosa caesalpiniifolia Benth. a technique relatively unexplored for this species. The primary goal was to ascertain whether air layering could effectively produce new clonal (genetically identical) plants. Additionally, the study aimed to establish and enhance a small-scale nursery for clonal plants. To this end, trials were conducted on segments of branches from six adult trees in a special setup which stimulates root growth using various indole-3-butyric acid (IBA) concentrations. Root development was monitored biweekly. Based on these experiments, a clonal mini-garden was established to observe the growth and health of these new plants, assessing the number of new shoots and mini-cuttings generated and their survival rates. The findings indicate that root development occurred under all conditions, although the IBA concentration did not significantly affect the outcome. The success of plant growth within the clonal mini-garden appeared to be linked to the quality of root development during the air layering process. Therefore, employing air layering to cultivate new Mimosa caesalpiniifolia plants is viable and can support the creation of a clonal mini-garden for subsequent propagation.

Soil fertility and plant nutrition in an organic olive orchard after 5 years of amendment with compost, biochar or their blend

The agronomic use of compost and biochar as soil amendments may exhibit contrasting results in terms of soil fertility and plant nutrition. The effects of the biennial application of biochar, compost and a blend of compost:biochar (90:10; % dw:dw) on the agronomical performance of an organically managed and well established 25-year-old olive orchard was assessed 5 years after the initial application. The agronomical evaluation was based on the assessment of the soil physical, chemical, and biological characteristics, and the assessment of the soil fertility by both crop production and nutritional status of the orchard, and the bioassay with olive plantlets. Biochar mainly benefited the physical properties (bulk density, total porosity, aeration, water retention capacity) of soil, especially in the top 0–5 cm. Compost and its blend with biochar improved microbial activity, soil nutritional status (increasing the content of soluble organic C, N, and P) and favoured the formation of aggregates in soil. The bioassay conducted with young plantlets confirmed the enhanced soil fertility status in the three amended treatments, particularly in the case of biochar and its blend with compost. However, this effect was not significantly observed in the adult plants after 5 years of application, reflecting the slow response of adult olive trees to changes in fertilization. Based on these results, alongside the desirable long-residence time of biochar in soil and the ready availability of compost, the blend of biochar with compost assayed in this study is defined as a valid strategy for preparing high quality soil organic amendments.

Environmental conditions differently shape leaf, seed and seedling trait composition between and within elevations of tropical montane forests

The composition of plant functional traits varies in response to environmental conditions due to processes of community assembly and species sorting. However, there is a lack of understanding of how plant trait composition responds to environmental conditions at different spatial scales and across the plant life cycle. We investigated the trait composition of leaves (specific leaf area), seeds (seed mass) and seedlings (initial seedling height) across elevations and within elevations in relation to soil and light conditions in a tropical montane forest in southern Ecuador. We surveyed traits and communities of adult trees, seeds and seedlings on nine plots at three elevations (1000–3000 m a.s.l.) and calculated community‐weighted mean trait values to analyse trait variation across and within elevations. In addition, we measured two environmental factors (soil C/N ratio and canopy openness) to quantify local‐scale variation in environmental conditions within elevations. We found that community‐weighted means of specific leaf area, seed mass and initial seedling height decreased consistently with increasing elevation. Within elevations, mean trait values of trees, seeds and seedlings responded differently to local‐scale environmental conditions. Specific leaf area decreased with increasing soil C/N ratio, and initial seedling height decreased with increasing canopy openness. Seed mass was associated neither with soil nor with light conditions. Our findings show that broad‐scale and local‐scale processes differently shape the composition of leaf, seed and seedling traits in tropical forests, indicating a scale‐dependence in trait–environment associations. Furthermore, plant traits corresponding to different life stages were related differently to environmental conditions within elevations. Community assembly processes may therefore lead to differences in species sorting at early and late plant life stages.

What do we know about the needle xylem structure of the genus Pinus?

Summary Studies of needle xylem structure (NXS) are of importance in understanding the survival, and functioning of conifers, particularly in response to environmental stressors. Herein, I review the current state-of-the-art about the NXS of genus Pinus, focusing on the xylem, tracheid, and pit structure. Genus Pinus is one of the most important and widely distributed genera of forest trees in the Northern Hemisphere. Pine species are adapted to different soil types and extreme environments imposed by elevation and latitude. They grow successfully in the boreal forest, the Mediterranean Basin, and in mountains. The importance of NXS for long-distance water transport in trees is discussed and the relationships between xylem structure and function are highlighted. Little is known about the NXS of pines, as such information was available only for 12 pine species. Moreover, current knowledge about the NXS of pines is mostly based on Pinus sylvestris L., especially regarding the effect of environmental conditions on NXS. So far, tracheid pit structure has been investigated in only one study. Although NXS is also significantly influenced by tree age, the position of needles within the crown, as well as the location of the cross-section along the longitudinal axis of the needle, a detailed needle sampling design is often missing. Hence, it is suggested to extend future studies to other pine species to explain their resistance to drought and cold. Additionally, increasing the number of studies on adult trees and distinguishing between the different types of environmental stress that a tree can face during its life cycle would be beneficial. I strongly appeal to precise description of needle sampling, which will allow us both intraspecific and interspecific comparisons. Increasing knowledge about the NXS of pines will help to better explain their resistance to environmental stress and predict their tolerance to future climate change.

Forest and soil fungal community dynamics are fuelled by root rot pathogen‐induced gaps

Abstract Forest dynamics are driven by micro‐disturbances leading to gap formation. Root rot pathogens can cause mortality to adult trees, which die forming gaps. However, little is known about the biotic and abiotic factors that govern gap creation and expansion such as tree infection or drought resilience, and what are the consequences for nutrient cycling and soil microbiota. We studied the dynamics of gaps created by Heterobasidion abietinum in mountain silver fir (Abies alba) forests from the Spanish Central Pyrenees. Tree‐ring width information was used to evaluate growth patterns of trees located within and at the edge of gaps and under closed canopy conditions. We analysed soil nutrient content and microbial structure at different positions with respect to the gap. Soil fungal community was also characterized by sequencing the ITS2 region. Gaps created by H. abietinum ranged 582–1072 m2 and gathered large amounts of standing and laying dead wood biomass amounting to up to 500 m3 ha−1 of coarse woody debris. This indicates that tree mortality had been occurring over decades, and it was preceded by a long‐term growth decline and impaired drought resilience. Root rot affected trees beyond the current limit of the gaps leading to growth decline, preventing canopy closure and allowing the release of suppressed trees within the gap. Gap formation did neither affect soil fertility nor fungal and bacterial biomass and diversity, but long‐distance ectomycorrhizal fungi were more abundant within gaps. Synthesis. Root rot pathogens play key ecological roles in forest dynamics at fine spatial scale. Heterobasidion abietinum infection, and its interaction with drought, creates and expands gaps by killing large trees and preventing surrounding trees from closing the gap. The survival of mycorrhizal networks to gap formation suggests little disruption of soil fungal communities.

Biomass, carbon stock and carbon dioxide sequestration by trees outside forests: A case study from Puducherry, India

Trees outside forests (ToF) play a vital role in reducing carbon from industrial activities and vehicles by sequestering and storing atmospheric Co2 generated as biomass. However, there is a scarcity of studies quantifying the biomass and carbon stock in the ToFs. To bridge this gap, we conducted a study on the potential of biomass and carbon dioxide sequestration in trees planted in Puducherry. Our findings show that the total above-ground biomass of adult trees in the city was 1926.03 Megagram (Mg), while belowground biomass was 244.47 Mg. The total carbon stored in adult trees was 966.53 Mg, while the volume of sequestered CO2 was 3547.17 Mg in the study area. To increase carbon dioxide sequestration in Puducherry town, we recommend increasing urban green cover and planting more fast-growing native species.

Pathogenicity and induced resistance in Larix kaempferi and Larix olgensis inoculated with Endoconidiophora fujiensis.

With climate warming and economic globalization, insect-microbe assemblages are becoming increasingly responsible for various devastating forest diseases worldwide. Japanese larch (Larix kaempferi) is extensively cultivated in China because of its high survival rate, rapid maturation and robust mechanical properties. Endoconidiophora fujiensis, an ophiostomatoid fungus associated with Ips subelongatus, has been identified as a lethal pathogen of L. kaempferi in Japan. However, there is a dearth of research on the pathogenicity of E. fujiensis in larches in China. Therefore, we investigated the pathogenicity of E. fujiensis in introduced L. kaempferi and indigenous larch (Larix olgensis) trees and compared the induced resistance responses to the pathogen in both tree species in terms of physiology and gene expression. Five-year-old saplings and 25-year-old adult trees of L. olgensis and L. kaempferi were inoculated in parallel during the same growing season. Endoconidiophora fujiensis exhibited high pathogenicity in both larch species, but particularly in L. kaempferi compared with L. olgensis adult trees; adult L. olgensis was more resistant to E. fujiensis than adult L. kaempferi, which was reflected in higher accumulation of defensive monoterpenes, such as myrcene, 3-carene and limonene and the earlier induction of defense genes catalase (CAT) and pathogenesis-related protein 1 (PR1). This study contributes to our understanding of the interactions between bark beetle-associated ophiostomatoid fungi and host larches, from phenotypic responses to alterations in secondary metabolites via defense- and metabolism-related gene activation, providing a valuable foundation for the management of larch diseases and pests in the future.

Long-Term Conservation for the Safeguard of Abies nebrodensis: An Endemic and Endangered Species of Sicily.

The combined approaches between ex situ and in situ conservation are of great importance for threatened species in urgent need of protection. This study aims to develop concrete actions to preserve the relic of 30 adult trees of the Sicilian fir (Abies nebrodensis) from extinction using long-term germplasm conservation in liquid nitrogen (LN, -196 °C). Pollen grains were collected, and their moisture content (MC) was measured. Then, viability (2,3,5-tryphenyl tetrazolium chloride, TTC), in vitro germinability, and enzymatic antioxidant activity (ascorbate peroxidase, APX; catalase, CAT) were evaluated before and after cryopreservation. Seeds collected from mature cones underwent X-ray analysis, and only full seeds were used to excise the zygotic embryos (ZEs) for cryopreservation. The MC percentage of ZEs was determined, and then they were plunged in LN with (+PVS2) or without (-PVS2) Plant Vitrification Solution 2; untreated ZEs were used as a control. Viability (TTC test) and in vitro germination were assessed for all ZEs (+PVS2, -PVS2, and control). Embryogenic callus (EC) lines obtained from mature ZEs were cryopreserved applying the 'encapsulation-dehydration' technique. This study has allowed, after optimizing cryopreservation protocols for pollen, ZEs, and EC of A. nebrodensis, to establish the first cryobank of this endangered species in Polizzi Generosa (Palermo, Italy), inside the 'Madonie Regional Park'. The strategy developed for Sicilian fir conservation will pave the way for similar initiatives for other critically endangered conifer species.