JournalTOCs

Frontiers in Forests and Global Change
Number of Followers: 3

This is an Open Access Journal

Open Access journal
ISSN (Online) 2624-893X
Published by Frontiers Media

[96 journals]

Potential alternative tree species to Fraxinus excelsior in European
forests
- Authors: Mathieu Lévesque, José Ignacio Bustamante Eduardo, Valentin Queloz
  Abstract: Common ash (Fraxinus excelsior L.) is a keystone tree species in Europe. However, since the 1990s, this species has been experiencing widespread decline and mortality due to ash dieback [Hymenoscyphus fraxineus (T. Kowalski) Baral, Queloz and Hosoya]. Besides H. fraxineus, emerald ash borer (Agrilus planipennis Fairmaire), an invasive alien pest already devastating ash trees in western Russia, is spreading westward and becoming an emerging threat to the remaining European ash populations. While efforts to control ash dieback continue to be a priority, it is becoming crucial to compensate for the loss of ash and its ecosystem services by elaborating restoration strategies, including the search for alternative native and non-native tree species. This review summarizes available knowledge on potential alternative tree species to common ash to help forest managers to cope with ash dieback. Although using natural regeneration and promoting tree species diversity can reduce the impacts of ash dieback in European forests, our review indicates that no native species alone or in combination can fully replace the ecological niche of common ash and its associated ecosystem services (e.g., biodiversity and timber). To fill this gap, forest managers have considered using non-native ash species that are tolerant to both H. fraxineus and A. planipennis and have similar ecological and forestry values as common ash. Of the 43 ash species reviewed, few non-native ash species (e.g., Fraxinus mandshurica Rupr. and Fraxinus platypoda Oliv.) have similar ecological characteristics to common ash and are tolerant to H. fraxineus and A. planipennis. However, the performance of non-native ash species in European forests, their invasiveness potential, and the risk of hybridization with native ash species are still unknown. With the current state of knowledge, it is thus too early to recommend the use of non-native ash species as a suitable option to deal with ash dieback. The priority should be the conservation, regeneration, and breeding of tolerant common ash populations to H. fraxineus, as well as the use of the natural regeneration of other native tree species. Our review highlights the need for controlled experimental plantations to better understand the regeneration ecology and invasiveness potential of non-native ash species prior to their utilization in natural forests.
  PubDate: 2023-02-02T00:00:00Z
Using dense Sentinel-2 time series to explore combined fire and drought
impacts in eucalypt forests
- Authors: Samuel Hislop, Christine Stone, Rebecca K. Gibson, Adam Roff, Brendan Choat, Rachael H. Nolan, Trung H. Nguyen, Angus J. Carnegie
  Abstract: Following one of the driest years on record, millions of hectares of forests in southeast Australia were burned in the 2019–2020 “Black Summer” wildfires. In addition to the areas burned, drought related canopy collapse, dieback and tree mortality was widely observed. In this paper, we present a method to map canopy damage due to drought and fire across a large area. Sentinel-2 satellite imagery was used in a monthly time series to highlight areas of forest where the Normalized Burn Ratio index was significantly below a pre-disturbance “stable” period. The stable period was defined as the 3 years prior to 2019 and the disturbance thresholds are based on bioregion specific standard deviations below pre-disturbance means. The novel methods enabled drought impacted forests to be identified, including those which were subsequently burned by wildfire. Across the 20 Mha of forests studied, 9.9 Mha (49%) fell below the disturbance threshold. Of that, 5.8 Mha was disturbed by fire and a further 4.1 Mha by drought outside of the fire extent. Within the fire extent, almost 0.9 Mha was identified as being significantly drought affected prior to being burned. An analysis of spectral recovery following substantial rainfall from February 2020 onward indicates that most of the areas impacted by both drought and fire have similar rates of recovery to those impacted only by fire. There are some areas, however, where the combined effects of the “double disturbance” appears to be hindering recovery. The methods presented here are easily transferrable and demonstrate an approach for monitoring forest disturbance at higher temporal and spatial scales than those typically used.
  PubDate: 2023-02-02T00:00:00Z
Editorial: Lianas, ecosystems, and global change
- Authors: Geertje M. F. van der Heijden, Stefan A. Schnitzer, Félicien Meunier
  PubDate: 2023-02-02T00:00:00Z
Monoculture plantations impede forest recovery: Evidence from the
regeneration of lowland subtropical forest in Hong Kong
- Authors: Huiling Zhu, Jinlong Zhang, Mang Lung Cheuk, Billy C. H. Hau, Gunter A. Fischer, Stephan W. Gale
  Abstract: Anthropogenic disturbance has led to widespread clearance and degradation of tropical forests, and tree planting has been promoted as an effective solution for recovery. However, trees have been overwhelmingly planted in monocultures or low-diversity mixes and this is expected to have profound, lasting impacts on forest structure, diversity, and functioning. In this study, we tested the extent to which historical vegetation transition types (VTTs) constrain forest recovery in a secondary tropical landscape in Hong Kong, South China. To do so, we overlaid vegetation types (forest, shrubland, pine plantation, grassland) identified in aerial photographs taken in 1956 and 1963 of a 20-ha plot situated in Tai Po Kau Nature Reserve, allowing us to define six historic VTTs, namely: FF (forest to forest), GP (grassland to plantation), GS (grassland to shrubland), SS (shrubland to shrubland), SF (shrubland to forest), and SP (shrubland to plantation). We compared present-day forest structure and species diversity among these VTTs, as determined from a census conducted in 2015, using incidence- and abundance-based rarefaction and extrapolation, and we assessed species’ association within VTTs using a torus translation test. Our results reveal that stem density and species diversity in naturally regenerated forests were more similar to those of old-growth forest, whereas species diversity in areas occupied by pine plantations was significantly lower as compared with naturally regenerated areas. Despite 60 years of recovery, pine plantations were characterised by a significantly greater proportion of negatively associated species, and late-seral species were still predominantly confined to old-growth patches. Present-day species distribution is chiefly explained by the combined effects of topography and VTT (17.1%), with VTT alone explaining 4.4%. Our study demonstrates that VTT has a significant long-term impact on forest regeneration and community assembly and, importantly, that monocultural plantations (forest plantation) can greatly impede forest recovery. Remnant old-growth forest patches merit priority protection, and active restoration, including thinning and enhancement planting, is necessary to facilitate forest succession.
  PubDate: 2023-02-01T00:00:00Z
Editorial: Fires in the wildland urban interface: An emerging global
phenomenon threatening modern society
- Authors: Guillermo E. Defossé
  PubDate: 2023-02-01T00:00:00Z
Old forest structural development drives complexity of nest webs in a
naturally disturbed boreal mixedwood forest landscape
- Authors: Philippe Cadieux, Pierre Drapeau, Ugo Ouellet-Lapointe, Alain Leduc, Louis Imbeau, Réjean Deschênes, Antoine Nappi
  Abstract: Structural complexity generated by forest development processes and tree species compositional changes provide key habitat features for vertebrate communities that rely upon tree size and decay processes for foraging, denning or nesting. Complexity of forest structure in old stands could not only be key for harboring increased taxonomic species diversity but also greater functional diversity through more complexity in networks of tree cavity dependent species. Using a nest web approach that hierarchically links cavity-bearing trees with cavity formation agents (natural decay processes and avian excavators) and cavity users (non-excavator species), we compared network characteristics of nest webs along a time since fire gradient in a naturally disturbed boreal mixedwood forest landscape in eastern North America. Since 2003, twelve 24 to 40 ha plots ranging from 61 to more than 245 years after fire were surveyed at the Lake Duparquet Research and Teaching Forest in Abitibi, Quebec, Canada to detect active nesting, and denning cavities. We found that network complexity both in terms of number of vertebrate species and number of interactions among species, increased along the age gradient and was significantly higher in the older stands than predicted by chance. Whereas cavity-nesting communities in old forests used a higher diversity of tree species over a wide range of decay stages, trembling aspen remained a key cavity-bearing tree throughout the age gradient. Woodpeckers were the main cavity formation agents whereas less than 1% of cavities originated from natural decay. The structural development of older forests is thus a driver for functional diversity in cavity-using vertebrate communities through higher interaction richness in nest webs, among cavity-bearing trees, excavators and non-excavating users. The pivotal contribution of the entire gradient of old forest cover types to the overall complexity of nest webs in the boreal mixedwood zone is also a key for the resilience of the cavity-using vertebrate community to natural disturbances. We discuss how such resilience may be compromised by even-aged industrial timber harvesting with short rotations that shifts the age structure of boreal landscapes toward regenerating and young pole forests whereas old forest cover types become below their historical range of variability.
  PubDate: 2023-01-27T00:00:00Z
Impacts of climate change and fruit tree expansion on key hydrological
components at different spatial scales
- Authors: Yarui Xu, Wenfei Liu, Houbao Fan, Fangfang Shen, Jianping Wu, Peng Liu, Dongxin Sang, Wanbin Qiu, Honglang Duan, Wei Cai
  Abstract: Assessing how fruit tree expansion and climate variability affect hydrological components (e.g., water yield, surface runoff, underground runoff, soil water, evapotranspiration, and infiltration) at different spatial scales is crucial for the management and protection of watersheds, ecosystems, and engineering design. The Jiujushui watershed (259.32 km2), which experienced drastic forest changes over the past decades, was selected to explore the response mechanisms of hydrological components to fruit tree expansion and climate variability at different spatial scales (whole basin and subbasin scale). Specifically, we set up two change scenarios (average temperature increase of 0.5°C and fruit tree area expansion of 18.97%) in the SWAT model by analyzing historical data (1961∼2011). Results showed that climate change reduced water yield, surface runoff, and underground runoff by 6.75, 0.37, and 5.91 mm, respectively. By contrast, the expansion of fruit trees increased surface runoff and water yield by 2.81 and 4.10 mm, respectively, but decreased underground runoff by 1 mm. Interestingly, the sub-basins showed different intensities and directions of response under climate change and fruit tree expansion scenarios. However, the downstream response was overall more robust than the upstream response. These results suggest that there may be significant differences in the hydrological effects of climate change and fruit tree expansion at different spatial scales, thus any land disturbance measures should be carefully considered.
  PubDate: 2023-01-27T00:00:00Z
Remote sensing methods for estimating tree species of forests in the Volyn
region, Ukraine
- Authors: Oleksandr Melnyk, Pavlo Manko, Ansgar Brunn
  Abstract: Forest classification is needed to solve a wide range of environmental issues related to of forest classes and succession processes, the extent of afforestation and deforestation and global environmental change. These applications require a very accurate mapping and monitoring of forest types. This article investigates the combination of modern open geographic information systems and remote sensing data in forest management tasks for a specific part of the Ukrainian state area. Based on the existing afforestation plans, the results of the unsupervised classification of Sentinel-2 images and the selection of forest species fragments with closed crowns as training data for supervised classification, classifiers of forest species of the study object were developed with and without taking into account age groups. A supervised classification of research objects is realized and the accuracy of the obtained results is evaluated. It is established that the accuracy of determining forest species on the basis of the proposed method is 90.3 and 91.4%, taking into account age groups and without taking them into account, respectively. Thus, it is found that the modeling of the age groups does not improve the classification result for the test area.
  PubDate: 2023-01-26T00:00:00Z
Does fragmentation contribute to the forest crisis in Germany'
- Authors: Deepika Mann, Charlotte Gohr, Jeanette S. Blumröder, Pierre L. Ibisch
  Abstract: Intact forests contribute to the ecosystem functionality of landscapes by storing and sequestering carbon, buffering and cooling the microclimate, and providing a range of related ecosystem functions. Forest fragmentation not only poses a threat to many organisms but also reduces the resistance and resilience of the ecosystem, which is especially relevant to the ongoing climate crisis. The effects of recent extreme heat years on forests in Germany have not been studied in detail for the influence of fragmentation. We investigate the relation of forest fragmentation with temperature and vitality in Germany per ecoregion at the canopy level using satellite imagery at 1-km and 30-m resolution. We compiled and correlated forest maps for connectivity based on Thiessen polygons, canopy temperatures on the hottest days based on land surface temperature, and forest vitality based on the maximum normalized difference vegetation index per growing season. We differentiated between ecoregions and main forest types. In 2022, larger intact tree-covered areas that are less fragmented have relatively low temperatures on hot days and higher overall vitality. Nearly 98% of the almost 1.95 million forest fragments at 30-m resolution in Germany are smaller than 1 km2, which cover nearly 30% of the total forest area. To counteract the forest crisis, forest and landscape management should aim to reduce fragmentation and maintain tree biomass and forest cover in the landscape. Increasing the size of continuous forest fragments contributes to ecosystem-based adaptation to climate change.
  PubDate: 2023-01-20T00:00:00Z
Effects of biochar and wood ash amendments in the soil-water-plant
environment of two temperate forest plantations
- Authors: Lur Moragues-Saitua, Ander Arias-González, Fernando Blanco, Garazi Benito-Carnero, Nahia Gartzia-Bengoetxea
  Abstract: Forest biomass is considered an alternative to fossil fuels in energy production, as part of global strategies for climate change mitigation. Application of by-products such as wood ash (WA) and biochar (BC) to soil could replace the nutrients removed by tree harvesting and could also increase soil carbon stocks. However, the extent to which these amendments can provide benefits depends on how the by-products interact with the soil-water-plant system. We studied the short-term responses of WA and BC application in two different mineral soil-water-plant systems in temperate forests: A. Typic Udorthent (TU) with mature Pinus radiata; B. Typic Dystrudept (TD) with young Quercus pyrenaica, to test the following hypotheses: (1) the application of WA and BC will increase nutrient uptake by plants, but (2) these products could induce toxicity in the soil-water-plant system, and (3) in case of no toxicity, plant biomass growth in these temperate forest soils will increase due to increased plant nutrient uptake. Biochar was applied at rates of 3.5, 10, and 20 Mg ha–1 and WA at rates of 1.5, 4.5, and 9 Mg ha–1 (calcium equivalent). A nitrogen enriched treatment was applied with the intermediate doses. Ecotoxicity testing indicated that WA and BC were not toxic, although Ni uptake increased in biomass of the TU after BC + N application. BC increased SOC stocks of both sites, depending on treatment. In TD BC increased K uptake by plants, but did not increase biomass. In summary, this study shows that the application of BC and WA had different effects on the soil -water-plant system in two different forest soils. This difference was attributed to (i) the soil characteristics, (ii) the application rates and (iii) whether or not nitrogen was applied. Long-term field experiments are required to test the performance and potential toxicity of these by-products as soil enhancers.
  PubDate: 2023-01-19T00:00:00Z
Provenance influences seed germination and phenotypic responses to water
restriction in the endemic Beilschmiedia miersii (Gay) Kosterm
- Authors: Carlos R. Magni, Paola L. Poch, Sergio E. Espinoza, Marco A. Yáñez, Eduardo E. Martínez, Alvaro A. Promis, Gabriel A. Mancilla
  Abstract: The higher drought intensity recorded in the last decades in the Mediterranean zone of Chile increased the level of threats of the endemic Beilschmiedia miersii (Gay) Kosterm and has raised concern about its capacity to face drought. In this study, we assessed the effect of seed provenance and mother tree on seed germination traits, seedling growth, biomass allocation, presence of cotyledons, and survival responses of B. miersii cultivated under two water treatments (well-watered versus water stress. Average pre-dawn plant water potentials of −0.9 and −4.5 MPa, respectively). The germination stage of this trial showed significant differences in germination capacity, germination energy, and the maximum value of Czabator. Provenances from the southern range of the species, with higher precipitation (Cantillana and El Arbol) had a better germination performance, however, once germinated, the ability of the seedlings to survive in the nursery was high only in two of the five provenances under study. The coastal and interior provenances with lower precipitations (El Pobre, Longotoma, and Antumapu) were not able to survive to the seedling stage (
  PubDate: 2023-01-19T00:00:00Z
Temperature, nutrient availability, and species traits interact to shape
elevation responses of Australian tropical trees
- Authors: Arun Singh Ramesh, Alexander W. Cheesman, Habacuc Flores-Moreno, Noel D. Preece, Darren M. Crayn, Lucas A. Cernusak
  Abstract: Elevation gradients provide natural laboratories for investigating tropical tree ecophysiology in the context of climate warming. Previously observed trends with increasing elevation include decreasing stem diameter growth rates (GR), increasing leaf mass per area (LMA), higher root-to-shoot ratios (R:S), increasing leaf δ13C, and decreasing leaf δ15N. These patterns could be driven by decreases in temperature, lower soil nutrient availability, changes in species composition, or a combination thereof. We investigated whether these patterns hold within the genus Flindersia (Rutaceae) along an elevation gradient (0–1,600 m) in the Australian Wet Tropics. Flindersia species are relatively abundant and are important contributors to biomass in these forests. Next, we conducted a glasshouse experiment to better understand the effects of temperature, soil nutrient availability, and species on growth, biomass allocation, and leaf isotopic composition. In the field, GR and δ15N decreased, whereas LMA and δ13C increased with elevation, consistent with observations on other continents. Soil C:N ratio also increased and soil δ15N decreased with increasing elevation, consistent with decreasing nutrient availability. In the glasshouse, relative growth rates (RGR) of the two lowland Flindersia species responded more strongly to temperature than did those of the two upland species. Interestingly, leaf δ13C displayed an opposite relationship with temperature in the glasshouse compared with that observed in the field, indicating the importance of covarying drivers in the field. Leaf δ15N increased in nutrient-rich compared to nutrient-poor soil in the glasshouse, like the trend in the field. There was a significant interaction for δ15N between temperature and species; upland species showed a steeper increase in leaf δ15N with temperature than lowland species. This could indicate more flexibility in nitrogen acquisition in lowland compared to upland species with warming. The distinguishing feature of a mountaintop restricted Flindersia species in the glasshouse was a very high R:S ratio in nutrient-poor soil at low temperatures, conditions approximating the mountaintop environment. Our results suggest that species traits interact with temperature and nutrient availability to drive observed elevation patterns. Capturing this complexity in models will be challenging but is important for making realistic predictions of tropical tree responses to global warming.
  PubDate: 2023-01-19T00:00:00Z
Current approaches for modeling ecosystem services and biodiversity in
agroforestry systems: Challenges and ways forward
- Authors: Muhammed Habib ur Rahman, Hella Ellen Ahrends, Ahsan Raza, Thomas Gaiser
  Abstract: Limited modeling studies are available for the process-based simulation of ecosystem services (ESS) and biodiversity (BD) in agroforestry systems (AFS). To date, limited field scale AFs models are available to simulate all possible ESS and BD together. We conducted an extensive systematic review of available agroforestry (AF), BD, and soil erosion models for the simulation potential of seven most desirable ESS in AFS. Simple to complex AF models have an inherent limitation of being objective-specific. A few complex and dynamic AF models did not meet the recent interest and demands for the simulation of ESS under AFS. Further, many ESS modules especially soil erosion, GHGs emission, groundwater recharge, onsite water retention, nutrients and pesticide leaching, and BD are often missing in available AF models, while some existing soil erosion models can be used in combination with AF models. Likewise mechanistic and process-based BD diversity models are lacking or found limited simulation potential for ESS under AFS. However, further efforts of model development and improvement (integration and coupling) are needed for the better simulation of complex interactive processes belonging to ESS under AFS. There are different possibilities but a proficient modeling approach for better reliability, flexibility, and durability is to integrate and couple them into a process-based dynamic modular structure. Findings of the study further suggested that crop modeling frameworks (MFW) like SIMPLACE and APSIM could be potential ones for the integration and coupling of different suitable modeling approaches (AF, soil protection, GHGs emission, flood prevention, carbon sequestration, onsite water retention, ground recharge, nutrient leaching, and BD modules) in one platform for dynamic process based ESS estimation on daily basis at the field scale.
  PubDate: 2023-01-18T00:00:00Z
Soil carbon, nitrogen, and phosphorus stoichiometry and its influencing
factors in Chinese fir plantations across subtropical China
- Authors: Ran Tong, Tonggui Wu, Bo Jiang, Zhigao Wang, Binglou Xie, Benzhi Zhou
  Abstract: The crucial roles of soil carbon (C) and nutrients and their stoichiometric characteristics in indicating the soil interior nutrient cycling and plant nutrient supply of forest ecosystems have been widely verified, whereas it has been less explored when considering the influencing factors regionally, especially for the widely cultivated plantation tree species. In the current study, the patterns of soil organic C (SOC), total nitrogen (TN), and total phosphorus (TP) stoichiometry in Chinese fir [Cunninghamia lanceolata (Lamb.) Hook] plantations across subtropical China were analyzed, and their influencing factors were also investigated. The results showed that the range of SOC: TN (C:N), SOC: TP (C:P), and TN: TP (N:P) ratios were 7.32–18.27, 20.15–230.48, and 2.11–15.05 with a mean value of 13.22, 83.50, and 6.05, respectively. Well-constrained correlations were found in SOC and TN, as well as in TN and TP. Soil TN and TP contents increased with increasing altitude, whereas soil C:N, C:P, and N:P ratios decreased. Soil TP content decreased, and the C:P ratio increased with increasing mean annual temperature (MAT) and annual total solar radiation (ATSR). Soil C:N, C:P, and N:P ratios increased with increased mean annual precipitation (MAP) and mean annual evaporation (MAE). Overall, our findings suggested that the soil nutrient supply is relatively adequate in Chinese fir plantations across subtropical China. Meanwhile, soil C, N, and P stoichiometric characteristics were affected by geographical and climatic variables to different degrees.
  PubDate: 2023-01-17T00:00:00Z
The impact of the Asian chestnut gall wasp (Dryocosmus kuriphilus) on
chestnut tree growth may be mediated by site
resources|Introduction|Methods|Results|Discussion
- Authors: Fernando Castedo-Dorado, Pedro Álvarez-Álvarez, María Josefa Lombardero
  Abstract: IntroductionThe Asian chestnut gall wasp (Dryocosmus kuriphilus) is a major pest of chestnut trees worldwide, seriously affecting chestnut cultivation. Information concerning the effects of gall wasp attack on diameter growth of chestnut trees is currently scarce and limited to coppice stands and to use of the growth of a non-target control species (unaffected by the pest) for reference purposes. The effects of the pest on widely-spaced plantations (grown at a much lower density than chestnut coppices) and the use of explicitly-observed annual infestation rate data remain to be explored.MethodsIn the present study, we analyzed the impact of the chestnut gall wasp on the diameter growth of chestnut trees, using data from 16 experimental plots established in widely-spaced plantations located in good quality sites. Two of the plots are in plantations where a susceptible hybrid chestnut clone and a chestnut clone resistant to the gall wasp coexist, whereas the remaining 14 plots are in Castanea sativa plantations where the level of gall wasp infestation varies across trees and years. The plots were surveyed to determine the diameter growth of the trees and the level of infestation during 5 years (2017–2021).ResultsThe infestation level corresponding to the theoretical damage threshold was surpassed inmost plots during the study period. Nevertheless, there were no differences in the growth of attacked and unaffected plants in the two plots planted with hybrid clones with contrasting susceptibility to the gall wasp. The attack had a modest effect in C. sativa plots, with a mean reduction in annual basal area increment of 9.9%.DiscussionThese findings apparently contradict previous reports of a marked reduction in radial growth of chestnut coppice trees due to gall wasp attack. The difference in findings may be related to increased compensation for herbivory with increasing levels of resources (especially light) in the plantations under study, which were less dense than previously studied stands. The study outcomes add to existing knowledge on the impact of chestnut gall wasp on wood formation and may have implications regarding planting site recommendations and subsequent stand management.
  PubDate: 2023-01-13T00:00:00Z
The death of Korean fir (Abies koreana) affects soil symbiotic fungal
microbiome: Preliminary findings
- Authors: Minsoo Jeong, Setu Bazie Tagele, Min-Ji Kim, Suk-Hyung Ko, Kwon-Su Kim, Jung-Goon Koh, Da-Ryung Jung, YoungJae Jo, YeonGyun Jung, Yeong-Jun Park, Min-Sueng Kim, Kyeongmo Lim, Jae-Ho Shin
  Abstract: The population of the Korean fir, Abies koreana, is declining at an accelerating rate, and the average mortality rate in 2019 exceeded 36.43% on Mt. Hallasan in Jeju Island, Republic of Korea. Several prior studies have reported different reasons with various interpretations, indicating that additional data, such as data on microbial communities that promote plant growth and resistance to abiotic stresses, are required to understand the phenomenon further. This is the first investigation that documents the changes in the soil microbial and fungal community and soil physicochemical properties resulting from the death of the Korean fir. In our case, high throughput sequencing data have been provided for the soil microbiome and mycobiome of Korean fir trees, identifying the microbial composition differences before and after the decline in the health of Korean fir trees. The results showed that the soil fungal community was considerably shaped in response to the decline in the health of Korean fir rather than the soil bacterial community. The decline in health or the death of Korean fir trees contributed to the decrease in diversity and dominance of symbiotic fungi such as Russula, Sebacina, and Phenoliferia in the forest ecosystem. It also weakened the complexity and ecological competition of the fungal co-occurrence network. Structural equation modeling showed that the death of Korean fir was strongly associated with the concentrations of soil nutrients such as available phosphorus (P2O5) and potassium ion (K+) concentrations and low moisture content, adversely affecting the symbiotic relationship with ectomycorrhizal fungi. Our findings shed light on the critical taxa of mycobiome of live and dead A. koreana plants and their relationship with ecological edaphic factors, highlighting their potential role as biomarkers for the death of Korean fir.
  PubDate: 2023-01-12T00:00:00Z
Soil fertility and drought interact to determine large variations in wood
production for a hyperdominant Amazonian tree
species|Introduction|Methods|Results|Discussion
- Authors: Flavia Machado Durgante, Niro Higuchi, Shinta Ohashi, John Ethan Householder, Adriano José Nogueira Lima, Moriyoshi Ishizuka, Florian Wittmann, Joaquim dos Santos, Vilany Matilla Colares Carneiro, Xiaomei Xu, Claudete Catanhede do Nascimento, Jochen Schöngart, Maria Teresa Fernandez Piedade, Adalberto Rodrigo Kossmann Schmitt, Yanka Laryssa Almeida Alves, Jennifer Lehman, Bruno Oliva Gimenez, Priscilla Maia Baggio, Lucas Kosvoski de Ourique, Susan Trumbore
  Abstract: IntroductionThe productivity of the Amazon Rainforest is related to climate and soil fertility. However, the degrees to which these interactions influence multiannual to decadal variations in tree diameter growth are still poorly explored.MethodsTo fill this gap, we used radiocarbon measurements to evaluate the variation in tree growth rates over the past decades in an important hyperdominant species, Eschweilera coriacea (Lecythidaceae), from six sites in the Brazilian Amazon that span a range of soil properties and climate.ResultsUsing linear mixed-effects models, we show that temporal variations in mean annual diameter increment evaluated over a specific time period reflect interactions between soil fertility and the drought index (SPEI-Standardized Precipitation and Evapotranspiration Index).DiscussionOur results indicate that the growth response of trees to drought is strongly dependent on soil conditions, a facet of forest productivity that is still underexplored, and which has great potential for improving predictions of future tropical tree growth in the face of projected climate change.
  PubDate: 2023-01-11T00:00:00Z
Modeling habitat suitability of Hippophae rhamnoides L. using MaxEnt under
climate change in China: A case study of H. r. sinensis and H. r.
turkestanica
- Authors: Xiao-hui He, Jian-hua Si, Li Zhu, Dong-meng Zhou, Chun-yan Zhao, Bing Jia, Chun-lin Wang, Jie Qin, Xing-lin Zhu
  Abstract: Hippophae rhamnoides is widely known for its important ecological, economic, and social benefits. It is known as the pioneer plant of soil and water conservation, with homology in food and medicine. With the climate warming in recent years, the numbers of this species and countries with this plant have decreased steadily. H. r. sinensis and H. r. turkestanica have the widest distribution area in China, which account for more than 90% of the total national Hippophae rhamnoides resources. We firstly screened the presence data and downscale the environment variables (climate and soil) by correlation analysis. Secondly, based on the 232 occurrence data of H. r. sinensis and 10 environmental variables, the 73 occurrence data of H. r. turkestanica and 11 environmental variables, we simulated and predicted their suitable habitats in China, both at the current time and in the 2050S (2041–2060), and analyzed the dominant factors effecting its distribution by using MaxEnt. Finally, we studied the habitat variations and centroid migrations of these subspecies under future climate scenarios using the spatial analysis function of ArcGIS. The results indicated that the area of suitable habitat for H. r. sinensis is much larger than that of H. r. trkestanica in China. The suitable habitat of H. r. sinensis is concentrated in the middle and upper reaches of the Yellow River, mainly distributed in Shaanxi, Shanxi, Sichuan, Qinghai, Gansu, Ningxia, Tibet, and Inner Mongolia, and that of H. r. trkestanica is mainly distributed in Xinjiang and Tibet. The former is mainly affected by bio13 (precipitation of the wettest month), bio11 (mean temperature of the coldest quarte) and bio3 (Isothermality), and the latter is mainly affected by bio13 (precipitation of the wettest month), bio2 (mean diurnal range) and bio15 (precipitation seasonality), and the former is also more stable in the face of future climate change. They are more susceptible to climate than soil in their survival. Although, the two subspecies tend to expand and migrate toward lower latitude under future climate scenarios, there are some differences. H. r. sinensis will migrate westward, while H. r. trkestanica will migrate eastward as a whole. They have a high stability of suitable habitat and are not at risk of extinction in the future. The study’s findings help to clarify the resource reserve of Hippophae rhamnoides L. in China, which will help to guide the protection of wild resources and to popularize artificial planting in suitable areas, and provides scientific basis for the protection of ecological environment.
  PubDate: 2023-01-11T00:00:00Z
Light effects on seedling growth in simulated forest canopy gaps vary
across species from different successional stages
- Authors: Lingyan Zhou, Madhav P. Thakur, Zhen Jia, Yu Hong, Wenjie Yang, Shuqing An, Xuhui Zhou
  Abstract: Tropical forests continue to suffer from various kinds of disturbances in the Anthropocene. An immediate impact of disturbances on forest ecosystems is the creation of numerous large and small canopy gaps, which dramatically affect forest structure and function. Yet, we know little about the effect of canopy gaps on forest successional trajectory. More specifically, the responses of seedlings from different successional stages to increased light intensity under large and small canopy gaps in understory remain unclear. In this study, dominant tree seedlings from early-, mid-, and late-successional stages were selected, respectively from a tropical montane forest in Hainan Island, China to study their growth rate, biomass and traits. Our results showed that the light condition under small canopy gaps (SG, 10–15% of full sunlight) and large canopy gaps (LG, 40–50% of full sunlight) induced greater increment of relative growth rates for seedlings from early- and mid-successional stages relative to that in late-successional stage. Both SG and LG also significantly increased photosynthesis rate, leaf area (LA), light saturation point (LSP), root mass ratio (RMR) and root: shoot ratio, but decreased specific leaf area (SLA) of seedlings across successional stages. Tree seedlings from the early-successional stage displayed the greatest decrease in leaf mass ratio, increase in LA, LSP, and RMR, in comparison to those from mid- and late- successional stages. Light condition and SLA were the most important factors for seedlings’ relative growth rate across successional stages. SLA connected the interaction between the light condition and successional stage on seedlings’ growth, thereby jointly explaining the 93% variation of seedlings’ growth, combining with area-based light saturated rate of CO2 assimilation. Our study highlights the distinct effect of disturbance-induced canopy gaps on seedling regeneration in the understory in tropical forest due to the variation of light intensity. We suspect that the seedlings from late-successional stage will recover relatively slow after disturbances causing canopy losses, which can have detrimental impacts on structure feature and successional trajectory in tropical forest, as well as forest-based ecosystem services.
  PubDate: 2023-01-11T00:00:00Z
Estimating the amount of British Columbia’s “big-treed” old growth:
Navigating messy indicators
- Authors: Karen Price, Dave Daust, Kiri Daust, Rachel Holt
  Abstract: British Columbia’s (BC) diverse forest ecosystems include highly productive old growth with global importance for carbon storage and biodiversity. Current estimates of the remaining amount of “big-treed” old growth vary 10-fold, creating uncertainty that challenges provincial attempts to shift management policy toward ecological integrity. This uncertainty arises from using different remotely sensed indicators and definitions of tree size. No ideal indicator exists. We attempt to improve clarity by evaluating the reliability of candidate indicators, calibrating selected indicators to improve consistency, and generating multiple estimates of the amount of big-treed old growth using calibrated indicators. To evaluate reliability, we compared inventory estimates of tree size and site productivity with measured tree size in 1,945 ground plots. To assess the amount of big-treed old growth, we determined an equivalent “big” size threshold for each indicator and calculated the area of old growth above the size threshold. Stand volume, tree density, basal area, and diameter estimates performed poorly; we selected tree height and two measures of site productivity for further analysis. Estimated tree height best indicated the current old growth size, followed by inventory-based site index and finally ecosystem-based site index. The calibrated indicators agreed that very little remaining old growth supports large trees (1.5–3.3% for the biggest trees; 6–13% including medium-sized trees that represent the largest growing trees in lower productivity interior ecosystems). Tree height cannot be used to compare the remaining area of big-treed old growth to the area expected naturally, an important input for ecological risk assessment and conservation planning because height data are lost from the inventory after harvest. The two calibrated site productivity indicators agreed that the amount remaining is less than 30% of the expected historical amount, posing a high risk to biodiversity and resilience. We recommend using estimated height to identify the biggest remaining old-growth stands for regional planning and calibrated inventory-based site index for risk assessment until a detailed ecosystem mapping has been verified to represent old-growth variability. To reduce uncertainty, we suggest that planning groups compare several indicators and analysis approaches, adjusted to ensure equivalence, and use precaution to avoid any unknowingly increasing risks.
  PubDate: 2023-01-09T00:00:00Z