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Relationship between Forest Ecophysiology and Environment
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Relationship between Forest Ecophysiology and Environment

A special issue of Forests (ISSN 1999-4907). This special issue belongs to the section "Forest Ecophysiology and Biology".

Deadline for manuscript submissions: closed (10 October 2020) | Viewed by 48105

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special Issue Editors

Prof. Dr. Roberto Tognetti

E-Mail Website
Guest Editor
Department of Agricultural, Environmental and Food Sciences, Università degli Studi del Molise, Campobasso, Italy
Interests: climate-smart forestry; forest ecophysiology; forest monitoring; biogeochemical cycles; resilience; mitigation; adaptation; biodiversity; forest restoration; disturbance
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. John D. Marshall

E-Mail Website
Guest Editor
Ecophysiology Unit, Department of Forest Ecology and Management, Swedish University of Agricultural Sciences (SLU), 901 83 Umeå, Sweden
Interests: biogeochemical cycles; carbon fluxes; nitrogen deposition; stable isotopes
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The goal of limiting the increase in global temperature gives forests a prominent role, mainly because they can be significant carbon sinks capable of removing carbon dioxide from the atmosphere. However, in addition to serving as carbon sinks, forest trees suffer from the negative impacts of climate change at certain points in time and in certain regions. These negative impacts include chronic water or heat stress and acute responses to strengthened disturbance events. Detecting how the intensification of disturbances and stresses will affect the trajectory of tree vulnerability (combination of a species exposure, resilience, and adaptive capacity to stress) is a major scientific challenge that requires the development of sensors to assess the resilience and tipping points of the three trillion trees on Earth.

In this Special Issue, we explore current research designed to assess thresholds for rapid tree decline and consequences associated with ecological change. In situ measurements of ecophysiological traits and time–series analysis of monitoring data are needed to reveal both subtle changes and abrupt deviations at appropriate spatial and temporal scales. A combined approach, involving innovative data collection and transmission methods, may provide an early warning system for trees operating beyond the normal or safe mode and may offer unique insights into ecological dynamics and physiological responses to climatic perturbations that are not represented by estimates of forest cover or biomass.

This Special Issue will comprise a selection of papers reporting recent advances in research on relationships between plant functions and the environment in natural forest ecosystems and in managed forest plantations. Original works and reviews are both welcome.

Prof. Dr. Roberto Tognetti
Prof. Dr. John D. Marshall
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Forests is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Climate change 
  • Environmental disturbance 
  • Forest resilience 
  • Tree adaptation

Published Papers (16 papers)

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Editorial

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3 pages, 657 KiB  
Editorial
Relationship between Forest Ecophysiology and Environment
by Roberto Tognetti and John D. Marshall
Forests 2021, 12(1), 68; https://0-doi-org.brum.beds.ac.uk/10.3390/f12010068 - 09 Jan 2021
Viewed by 1861
Abstract
Although aspects of forest ecophysiology and forest environments have received considerable attention from research scientists in the last three decades, assessment of implications for meeting the climate targets and international agreements is still a matter of debate [...] Full article
(This article belongs to the Special Issue Relationship between Forest Ecophysiology and Environment)

Research

Jump to: Editorial

21 pages, 6147 KiB  
Article
Photosynthetic and Morphological Acclimation to High and Low Light Environments in Petasites japonicus subsp. giganteus
by Ray Deguchi and Kohei Koyama
Forests 2020, 11(12), 1365; https://0-doi-org.brum.beds.ac.uk/10.3390/f11121365 - 19 Dec 2020
Cited by 14 | Viewed by 3379
Abstract
Within each species, leaf traits such as light-saturated photosynthetic rate or dark respiration rate acclimate to local light environment. Comparing only static physiological traits, however, may not be sufficient to evaluate the effects of such acclimation in the shade because the light environment [...] Read more.
Within each species, leaf traits such as light-saturated photosynthetic rate or dark respiration rate acclimate to local light environment. Comparing only static physiological traits, however, may not be sufficient to evaluate the effects of such acclimation in the shade because the light environment changes diurnally. We investigated leaf photosynthetic and morphological acclimation for a perennial herb, butterbur (Petasites japonicus (Siebold et Zucc.) Maxim. subsp. giganteus (G.Nicholson) Kitam.) (Asteraceae), in both a well-lit clearing and a shaded understory of a temperate forest. Diurnal changes in light intensity incident on the leaves were also measured on a sunny day and an overcast day. Leaves in the clearing were more folded and upright, whereas leaves in the understory were flatter. Leaf mass per area (LMA) was approximately twofold higher in the clearing than in the understory, while light-saturated photosynthetic rate and dark respiration rate per unit mass of leaf were similar between the sites. Consequently, both light-saturated photosynthetic rate and dark respiration rate per unit area of leaf were approximately twofold higher in the clearing than in the understory, consistent with previous studies on different species. Using this experimental dataset, we performed a simulation in which sun and shade leaves were hypothetically exchanged to investigate whether such plasticity increased carbon gain at each local environment. As expected, in the clearing, the locally acclimated sun leaves gained more carbon than the hypothetically transferred shade leaves. By contrast, in the understory, the daily net carbon gain was similar between the simulated sun and shade leaves on the sunny day due to the frequent sunflecks. Lower LMA and lower photosynthetic capacity in the understory reduced leaf construction cost per area rather than maximizing net daily carbon gain. These results indicate that information on static photosynthetic parameters may not be sufficient to evaluate shade acclimation in forest understories. Full article
(This article belongs to the Special Issue Relationship between Forest Ecophysiology and Environment)
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15 pages, 3511 KiB  
Article
Redeployment of Shoots into Better-Lit Positions within the Crowns of Saplings of Five Species with Different Growth Patterns
by Kohei Koyama, Hiroyuki Shirakawa and Kihachiro Kikuzawa
Forests 2020, 11(12), 1301; https://0-doi-org.brum.beds.ac.uk/10.3390/f11121301 - 03 Dec 2020
Cited by 7 | Viewed by 2271
Abstract
Research Highlights: We demonstrate the first quantitative evidence that the shoot shedding of fast-growing species growing in a high-light environment is part of the process of shoot redeployment into better-lit outer parts of the crown. Background and Objectives: Light foraging by redeploying organs [...] Read more.
Research Highlights: We demonstrate the first quantitative evidence that the shoot shedding of fast-growing species growing in a high-light environment is part of the process of shoot redeployment into better-lit outer parts of the crown. Background and Objectives: Light foraging by redeploying organs from shaded regions of a tree crown into better-lit regions is considered to apply to both leaves and shoots. To date, however, this hypothesis has never been tested for shoots. Materials and Methods: We investigated the shoot dynamics of saplings of five deciduous woody species. We included fast-growing and slow-growing species (Alnus sieboldiana Matsum., Castanea crenata Siebold & Zucc., Betula ermanii Cham., Acer distylum Siebold & Zucc., and Fagus crenata Blume). Results: Shoots in the shaded regions of the crowns of the fast-growing trees showed higher mortality rates than those at better-lit positions. Because of the selective shedding of the shaded shoots, at the end of the growth period the light environment experienced by the shoots that survived until the following spring was similar to that at the early stage of the same growth period. By contrast, the slow-growing trees displayed slow and determinate growth, with a very low mortality rate of shoots at all positions in the crown. Conclusions: The rapid shoot turnover of the fast-growing species resulted in the redeployment of shoots into better-lit positions within the tree crown in a manner similar to the redeployment of leaves. Full article
(This article belongs to the Special Issue Relationship between Forest Ecophysiology and Environment)
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20 pages, 3065 KiB  
Article
Environmental Effects on Carbon Isotope Discrimination from Assimilation to Respiration in a Coniferous and Broad-Leaved Mixed Forest of Northeast China
by Haoyu Diao, Anzhi Wang, Fenghui Yuan, Dexin Guan, Guanhua Dai and Jiabing Wu
Forests 2020, 11(11), 1156; https://0-doi-org.brum.beds.ac.uk/10.3390/f11111156 - 30 Oct 2020
Cited by 14 | Viewed by 2130
Abstract
Carbon (C) isotope discrimination during photosynthetic CO2 assimilation has been extensively studied, but the whole process of fractionation from leaf to soil has been less well investigated. In the present study, we investigated the δ13C signature along the C transfer [...] Read more.
Carbon (C) isotope discrimination during photosynthetic CO2 assimilation has been extensively studied, but the whole process of fractionation from leaf to soil has been less well investigated. In the present study, we investigated the δ13C signature along the C transfer pathway from air to soil in a coniferous and broad-leaved mixed forest in northeast China and examined the relationship between δ13C of respiratory fluxes (leaf, trunk, soil, and the entire ecosystem) and environmental factors over a full growing season. This study found that the δ13C signal of CO2 from canopy air was strongly imprinted in the organic and respiratory pools throughout C transfer due to the effects of discrimination and isotopic mixing on C assimilation, allocation, and respiration processes. A significant difference in isotopic patterns was found between conifer and broadleaf species in terms of seasonal variations in leaf organic matter. This study also found that δ13C in trunk respiration, compared with that in leaf and soil respiration, was more sensitive to seasonal variations of environmental factors, especially soil temperature and soil moisture. Variation in the δ13C of ecosystem respiration was correlated with air temperature with no time lag and correlated with soil temperature and vapor pressure deficit with a lag time of 10 days, but this correlation was relatively weak, indicating a delayed linkage between above- and belowground processes. The isotopic linkage might be confounded by variations in atmospheric aerodynamic and soil diffusion conditions. These results will help with understanding species differences in isotopic patterns and promoting the incorporation of more influencing factors related to isotopic variation into process-based ecosystem models. Full article
(This article belongs to the Special Issue Relationship between Forest Ecophysiology and Environment)
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20 pages, 3938 KiB  
Article
Detecting Growth Phase Shifts Based on Leaf Trait Variation of a Canopy Dipterocarp Tree Species (Parashorea chinensis)
by Yun Deng, Xiaobao Deng, Jinlong Dong, Wenfu Zhang, Tao Hu, Akihiro Nakamura, Xiaoyang Song, Peili Fu and Min Cao
Forests 2020, 11(11), 1145; https://0-doi-org.brum.beds.ac.uk/10.3390/f11111145 - 29 Oct 2020
Cited by 7 | Viewed by 2174
Abstract
Canopy species need to shift their adaptive strategy to acclimate to very different light environments as they grow from seedlings in the understory to adult trees in the canopy. However, research on how to quantitively detect ecological strategy shifts in plant ontogeny is [...] Read more.
Canopy species need to shift their adaptive strategy to acclimate to very different light environments as they grow from seedlings in the understory to adult trees in the canopy. However, research on how to quantitively detect ecological strategy shifts in plant ontogeny is scarce. In this study, we hypothesize that changes in light and tree height levels induce transitions in ecological strategies, and growth phases representing different adaptive strategies can be classified by leaf trait variation. We examined variations in leaf morphological and physiological traits across a vertical ambient light (represented by the transmittance of diffuse light, %TRANS) and tree height gradient in Parashorea chinensis, a large canopy tree species in tropical seasonal rainforest in Southwestern China. Multivariate regression trees (MRTs) were used to detect the split points in light and height gradients and classify ontogenetic phases. Linear piecewise regression and quadratic regression were used to detect the transition point in leaf trait responses to environmental variation and explain the shifts in growth phases and adaptive strategies. Five growth phases of P. chinensis were identified based on MRT results: (i) the vulnerable phase, with tree height at less than 8.3 m; (ii) the suppressed phase, with tree height between 8.3 and 14.9 m; (iii) the growth release phase, with tree height between 14.9 and 24.3 m; (iv) the canopy phase, with tree height between 24.3 and 60.9 m; and (v) the emergent phase, with tree height above 60.9 m. The suppressed phase and canopy phase represent “stress-tolerant” and “competitive” strategies, respectively. Light conditions drive the shift from the “stress-tolerant” to the “competitive” strategy. These findings help us to better understand the regeneration mechanisms of canopy species in forests. Full article
(This article belongs to the Special Issue Relationship between Forest Ecophysiology and Environment)
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18 pages, 3761 KiB  
Article
How Do Mediterranean Pine Trees Respond to Drought and Precipitation Events along an Elevation Gradient?
by Sonja Szymczak, Martin Häusser, Emilie Garel, Sébastien Santoni, Frédéric Huneau, Isabel Knerr, Katja Trachte, Jörg Bendix and Achim Bräuning
Forests 2020, 11(7), 758; https://0-doi-org.brum.beds.ac.uk/10.3390/f11070758 - 14 Jul 2020
Cited by 16 | Viewed by 2900
Abstract
Drought is a major factor limiting tree growth and plant vitality. In the Mediterranean region, the length and intensity of drought stress strongly varies with altitude and site conditions. We used electronic dendrometers to analyze the response of two native pine species to [...] Read more.
Drought is a major factor limiting tree growth and plant vitality. In the Mediterranean region, the length and intensity of drought stress strongly varies with altitude and site conditions. We used electronic dendrometers to analyze the response of two native pine species to drought and precipitation events. The five study sites were located along an elevation gradient on the Mediterranean island of Corsica (France). Positive stem increment in the raw dendrometer measurements was separated into radial stem growth and stem swelling/shrinkage in order to determine which part of the trees’ response to climate signals can be attributed to growth. Precipitation events of at least 5 mm and dry periods of at least seven consecutive days without precipitation were determined over a period of two years. Seasonal dynamics of stem circumference changes were highly variable among the five study sites. At higher elevations, seasonal tree growth showed patterns characteristic for cold environments, while low-elevation sites showed bimodal growth patterns characteristic of drought prone areas. The response to precipitation events was uniform and occurred within the first six hours after the beginning of a precipitation event. The majority of stem circumference increases were caused by radial growth, not by stem swelling due to water uptake. Growth-induced stem circumference increase occurred at three of the five sites even during dry periods, which could be attributed to stored water reserves within the trees or the soils. Trees at sites with soils of low water-holding capacity were most vulnerable to dry periods. Full article
(This article belongs to the Special Issue Relationship between Forest Ecophysiology and Environment)
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15 pages, 4486 KiB  
Article
An ERF Transcription Factor Gene from Malus baccata (L.) Borkh, MbERF11, Affects Cold and Salt Stress Tolerance in Arabidopsis
by Deguo Han, Jiaxin Han, Guohui Yang, Shuang Wang, Tianlong Xu and Wenhui Li
Forests 2020, 11(5), 514; https://0-doi-org.brum.beds.ac.uk/10.3390/f11050514 - 02 May 2020
Cited by 36 | Viewed by 2749
Abstract
Apple, as one of the most important economic forest tree species, is widely grown in the world. Abiotic stress, such as low temperature and high salt, affect apple growth and development. Ethylene response factors (ERFs) are widely involved in the responses of plants [...] Read more.
Apple, as one of the most important economic forest tree species, is widely grown in the world. Abiotic stress, such as low temperature and high salt, affect apple growth and development. Ethylene response factors (ERFs) are widely involved in the responses of plants to biotic and abiotic stresses. In this study, a new ethylene response factor gene was isolated from Malus baccata (L.) Borkh and designated as MbERF11. The MbERF11 gene encoded a protein of 160 amino acid residues with a theoretical isoelectric point of 9.27 and a predicated molecular mass of 17.97 kDa. Subcellular localization showed that MbERF11 was localized to the nucleus. The expression of MbERF11 was enriched in root and stem, and was highly affected by cold, salt, and ethylene treatments in M. baccata seedlings. When MbERF11 was introduced into Arabidopsis thaliana, it greatly increased the cold and salt tolerance in transgenic plant. Increased expression of MbERF11 in transgenic A. thaliana also resulted in higher activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), higher contents of proline and chlorophyll, while malondialdehyde (MDA) content was lower, especially in response to cold and salt stress. Therefore, these results suggest that MbERF11 probably plays an important role in the response to cold and salt stress in Arabidopsis by enhancing the scavenging capability for reactive oxygen species (ROS). Full article
(This article belongs to the Special Issue Relationship between Forest Ecophysiology and Environment)
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14 pages, 2176 KiB  
Article
The Role of Climate Niche, Geofloristic History, Habitat Preference, and Allometry on Wood Density within a California Plant Community
by Rebecca A. Nelson, Emily J. Francis, Joseph A. Berry, William K. Cornwell and Leander D. L. Anderegg
Forests 2020, 11(1), 105; https://0-doi-org.brum.beds.ac.uk/10.3390/f11010105 - 14 Jan 2020
Cited by 7 | Viewed by 3251
Abstract
Research Highlights: To better understand within-community variation in wood density, our study demonstrated that a more nuanced approach is required beyond the climate–wood density correlations used in global analyses. Background and Objectives: Global meta-analyses have shown higher wood density is associated with higher [...] Read more.
Research Highlights: To better understand within-community variation in wood density, our study demonstrated that a more nuanced approach is required beyond the climate–wood density correlations used in global analyses. Background and Objectives: Global meta-analyses have shown higher wood density is associated with higher temperatures and lower rainfall, while site-specific studies have explained variation in wood density with structural constraints and allometry. On a regional scale, uncertainty exists as to what extent climate and structural demands explain patterns in wood density. We explored the role of species climate niche, geofloristic history, habitat specialization, and allometry on wood density variation within a California forest/chaparral community. Materials and Methods: We collected data on species wood density, climate niche, geofloristic history, and riparian habitat specialization for 20 species of trees and shrubs in a California forest. Results: We found a negative relationship between wood density and basal diameter to height ratio for riparian species and no relationship for non-riparian species. In contrast to previous studies, we found that climate signals had weak relationships with wood density, except for a positive relationship between wood density and the dryness of a species’ wet range edge (species with drier wet range margins have higher wood density). Wood density, however, did not correlate with the aridity of species’ dry range margins. Geofloristic history had no direct effect on wood density or climate niche for modern California plant communities. Conclusions: Within a California plant community, allometry influences wood density for riparian specialists, but non-riparian plants are ‘overbuilt’ such that wood density is not related to canopy structure. Meanwhile, the relationship of wood density to species’ aridity niches challenges our classic assumptions about the adaptive significance of high wood density as a drought tolerance trait. Full article
(This article belongs to the Special Issue Relationship between Forest Ecophysiology and Environment)
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11 pages, 1267 KiB  
Article
Tree Growth and Water-Use Efficiency Do Not React in the Short Term to Artificially Increased Nitrogen Deposition
by Francesco Giammarchi, Pietro Panzacchi, Maurizio Ventura and Giustino Tonon
Forests 2020, 11(1), 47; https://0-doi-org.brum.beds.ac.uk/10.3390/f11010047 - 31 Dec 2019
Cited by 7 | Viewed by 2070
Abstract
Increasing atmospheric CO2 concentration and nitrogen deposition are, among the global change related drivers, those playing a major role on forests carbon sequestration potential, affecting both their productivity and water-use efficiency. Up to now, results are however contrasting, showing that the processes [...] Read more.
Increasing atmospheric CO2 concentration and nitrogen deposition are, among the global change related drivers, those playing a major role on forests carbon sequestration potential, affecting both their productivity and water-use efficiency. Up to now, results are however contrasting, showing that the processes underlying them are far from being fully comprehended. In this study, we adopted an innovative approach to simulate the increase of N deposition in a sessile oak forest in North-Eastern Italy, by fertilizing both from above and below the canopy. We observed the dynamics of basal area increment, intrinsic water-use efficiency and of several leaf functional traits over 4 years, to evaluate how the added nitrogen and the two different fertilization system could affect them. We were not able, however, to detect any shift, besides a common yearly variability related to a prevailing background environmental forcing. To this end, we considered as relevant factors both the short time-span of the observation and the relatively low rate of applied nitrogen. Therefore, we stress the importance of long-term, manipulative experiments to improve the understanding of the C sequestration and mitigation ability of forests in response to increased N deposition. Full article
(This article belongs to the Special Issue Relationship between Forest Ecophysiology and Environment)
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18 pages, 2427 KiB  
Article
Tree Growth and Wood Quality in Pure Vs. Mixed-Species Stands of European Beech and Calabrian Pine in Mediterranean Mountain Forests
by Diego Russo, Pasquale A. Marziliano, Giorgio Macrì, Giuseppe Zimbalatti, Roberto Tognetti and Fabio Lombardi
Forests 2020, 11(1), 6; https://0-doi-org.brum.beds.ac.uk/10.3390/f11010006 - 18 Dec 2019
Cited by 13 | Viewed by 3800
Abstract
Mixed-species forests may deliver more forest functions and services than monocultures, as being considered more resistant to disturbances than pure stands. However, information on wood quality in mixed-species vs. corresponding pure forests is poor. In this study, nine plots grouped into three triplets [...] Read more.
Mixed-species forests may deliver more forest functions and services than monocultures, as being considered more resistant to disturbances than pure stands. However, information on wood quality in mixed-species vs. corresponding pure forests is poor. In this study, nine plots grouped into three triplets of pure and mixed-species stands of European beech and Calabrian pine (three dominated by European beech, three dominated by Calabrian pine, and three mixed-species plots) were analysed. We evaluated tree growth and wood quality through dendrochronological approaches and non-destructive technologies (acoustic detection), respectively, hypothesizing that the mixture might improve the fitness of each species and its wood quality. A linear mixed model was applied to test the effects of exogenous influences on the basal area index (BAI) and the dynamic modulus of elasticity (MOEd). The recruitment period (Rp) was studied to verify whether wood quality was independent from stem radial growth patterns. Results showed that the mixture effect influenced both wood quality and BAI. In the mixed-species plots, for each species, MOEd values were significantly higher than in the corresponding pure stands. The mixture effect aligned MOEd values, making wood quality uniform across the different diameter classes. In the mixed-species plots, a significant positive relationship between MOEd and Rp, but also significantly higher BAI values than in the pure plots, were found for European beech, but not for Calabrian pine. The results suggest the promotion of mixing of European beech and Calabrian pine in this harsh environment to potentially improve both tree growth and wood quality. Full article
(This article belongs to the Special Issue Relationship between Forest Ecophysiology and Environment)
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17 pages, 3551 KiB  
Article
Autotoxicity Hinders the Natural Regeneration of Cinnamomum migao H. W. Li in Southwest China
by Xiaolong Huang, Jingzhong Chen, Jiming Liu, Jia Li, Mengyao Wu and Bingli Tong
Forests 2019, 10(10), 919; https://0-doi-org.brum.beds.ac.uk/10.3390/f10100919 - 18 Oct 2019
Cited by 15 | Viewed by 3373
Abstract
Autotoxicity is a widespread phenomenon in nature and is considered to be the main factor affecting new natural recruitment of plant populations, which was proven in many natural populations. Cinnamomum migao H. W. Li is an endemic medicinal woody plant species mainly distributed [...] Read more.
Autotoxicity is a widespread phenomenon in nature and is considered to be the main factor affecting new natural recruitment of plant populations, which was proven in many natural populations. Cinnamomum migao H. W. Li is an endemic medicinal woody plant species mainly distributed in Southwestern China and is defined as an endangered species by the Red Paper of Endangered Plants in China. The lack of seedlings is considered a key reason for population degeneration; however, no studies were conducted to explain its causes. C. migao contains substances with high allelopathic potential, such as terpenoids, phenolics, and flavonoids, and has strong allelopathic effects on other species. Therefore, we speculate that one of the reasons for C. migao seedling scarcity in the wild is that it exhibits autotoxic allelopathy. In this study, which was performed from the perspective of autotoxicity, we collected leaves, pericarp, seeds, and branches of the same population; we simulated the effects of decomposition and release of litter from these different anatomical parts of C. migao in the field; and we conducted 210-day control experiments on seedling growth, with different concentration gradients, using associated aqueous extracts. The results showed that the leaf aqueous extract (leafAE) significantly inhibited growth indicators and increased damage of the lipid structure of the cell membrane of seedlings, suggesting that autotoxicity from C. migao is a factor restraining seedling growth. The results of the analyses of soil properties showed that, compared with the other treatments, leafAE treatment inhibited soil enzyme activity and also had an impact on soil fungi. Although leafAE could promote soil fertility to some extent, it did not change the effect of autotoxic substances on seedling growth. We conclude that autotoxicity is the main obstacle inhibiting seedling growth and the factor restraining the natural regeneration of C. migao. Full article
(This article belongs to the Special Issue Relationship between Forest Ecophysiology and Environment)
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15 pages, 2063 KiB  
Article
Reasons for the Extremely Small Population of putative hybrid Sonneratia × hainanensis W.C. Ko (Lythraceae)
by Mengwen Zhang, Xiaobo Yang, Wenxing Long, Donghai Li and Xiaobo Lv
Forests 2019, 10(6), 526; https://0-doi-org.brum.beds.ac.uk/10.3390/f10060526 - 25 Jun 2019
Cited by 4 | Viewed by 2985
Abstract
Sonneratia × hainanensis, a species once endemic to Hainan Island in China, is now endangered. China’s State Forestry Administration lists this species as a wild plant species with an extremely small population. Field fixed-point investigations, artificial pollination, and laboratory experiments, as well [...] Read more.
Sonneratia × hainanensis, a species once endemic to Hainan Island in China, is now endangered. China’s State Forestry Administration lists this species as a wild plant species with an extremely small population. Field fixed-point investigations, artificial pollination, and laboratory experiments, as well as other methods, were applied to study the reproductive system and seed germination of S. × hainanensis to elucidate the reasons for the endangerment of this species. The results are as follows: (1) Outcrossing index, pollen-ovule ratio, and artificial pollination showed S. × hainanensis has a mixed mating system and mainly focuses on outcrossing with some self-compatibility. (2) Fruit and seed placement tests showed that the fruit predators on the ground were mainly Fiddler crab and squirrel, with the predation rates being 100%. The artificially spread seeds do not germinate under natural conditions. The mean seed destruction rate and remaining rate of were 82.5% and 17.5%. (3) Seeds need to germinate under ambient light conditions, with an optimal photoperiod of 12 h. Seed germination is extremely sensitive to low temperatures because of optimum temperatures from 30 °C to 40 °C. At an optimal temperature of 35 °C, the seeds germinate under salinities ranging from 0‰ to 7.5‰, with an optimal salinity of 2.5‰, which shows the sensitivity of seed germination to salinity, with low salinity promoting germination, whereas high salinity inhibits germination. These findings indicate that the limited regeneration of S. × hainanensis is caused by the following: (1) Pollen limitation and inbreeding recession caused by the extremely small population of S. × hainanensis. (2) Seeds near parent trees are susceptible not only to high fruit drop rate, but to high predation beneath the parent trees′ canopy as well. (3) Seed germination has weak adaptability to light, temperature, and salinity. Full article
(This article belongs to the Special Issue Relationship between Forest Ecophysiology and Environment)
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21 pages, 16867 KiB  
Article
Role of Plant Traits in Photosynthesis and Thermal Damage Avoidance under Warmer and Drier Climates in Boreal Forests
by Guiomar Ruiz-Pérez, Samuli Launiainen and Giulia Vico
Forests 2019, 10(5), 398; https://0-doi-org.brum.beds.ac.uk/10.3390/f10050398 - 08 May 2019
Cited by 4 | Viewed by 4762
Abstract
In the future, boreal forests will face warmer and in some cases drier conditions, potentially resulting in extreme leaf temperatures and reduced photosynthesis. One potential and still partially unexplored avenue to prepare boreal forest for future climates is the identification of plant traits [...] Read more.
In the future, boreal forests will face warmer and in some cases drier conditions, potentially resulting in extreme leaf temperatures and reduced photosynthesis. One potential and still partially unexplored avenue to prepare boreal forest for future climates is the identification of plant traits that may support photosynthetic rates under a changing climate. However, the interplay among plant traits, soil water depletion and the occurrence of heat stress has been seldom explored in boreal forests. Here, a mechanistic model describing energy and mass exchanges among the soil, plant and atmosphere is employed to identify which combinations of growing conditions and plant traits allow trees to simultaneously keep high photosynthetic rates and prevent thermal damage under current and future growing conditions. Our results show that the simultaneous lack of precipitation and warm temperatures is the main trigger of thermal damage and reduction of photosynthesis. Traits that facilitate the coupling of leaves to the atmosphere are key to avoid thermal damage and guarantee the maintenance of assimilation rates in the future. Nevertheless, the same set of traits may not maximize forest productivity over current growing conditions. As such, an effective trait selection needs to explicitly consider the expected changes in the growing conditions, both in terms of averages and extremes. Full article
(This article belongs to the Special Issue Relationship between Forest Ecophysiology and Environment)
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12 pages, 2609 KiB  
Article
No Ontogenetic Shifts in C-, N- and P-Allocation for Two Distinct Tree Species along Elevational Gradients in the Swiss Alps
by Jian-Feng Liu, Ze-Ping Jiang, Marcus Schaub, Arthur Gessler, Yan-Yan Ni, Wen-Fa Xiao and Mai-He Li
Forests 2019, 10(5), 394; https://0-doi-org.brum.beds.ac.uk/10.3390/f10050394 - 05 May 2019
Cited by 2 | Viewed by 2435
Abstract
Most of our knowledge about forest responses to global environmental changes is based on experiments with seedlings/saplings grown in artificially controlled conditions. We do not know whether this knowledge will allow us to upscale to larger and mature trees growing in situ. In [...] Read more.
Most of our knowledge about forest responses to global environmental changes is based on experiments with seedlings/saplings grown in artificially controlled conditions. We do not know whether this knowledge will allow us to upscale to larger and mature trees growing in situ. In the present study, we used elevation as a proxy of various environmental factors, to examine whether there are ontogenetic differences in carbon and nutrient allocation of two major treeline species (Pinus cembra L. and Larix decidua Mill.) along elevational gradients (i.e., environmental gradient) in the Swiss alpine treeline ecotone (~300 m interval). Young and adult trees grown at the same elevation had similar levels of non-structural carbohydrates (NSCs), total nitrogen (TN), and phosphorus (TP), except for August leaf sugars and August leaf TP in P. cembra at the treeline. We did not detect any interaction between tree age and elevation on tissue concentration of NSCs, TN, and TP across leaf, shoot, and root tissues for both species, indicating that saplings and mature trees did not differ in their carbon and nutrient responses to elevation (i.e., no ontogenetic differences). With respect to carbon and nutrient allocation strategies, our results show that young and adult trees of both deciduous and evergreen tree species respond similarly to environmental changes, suggesting that knowledge gained from controlled experiments with saplings can be upscaled to adult trees, at least if the light is not limited. This finding advances our understanding of plants’ adaptation strategies and has considerable implications for future model-developments. Full article
(This article belongs to the Special Issue Relationship between Forest Ecophysiology and Environment)
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14 pages, 3221 KiB  
Article
Atmospheric Nitrogen Dioxide Improves Photosynthesis in Mulberry Leaves via Effective Utilization of Excess Absorbed Light Energy
by Yue Wang, Weiwei Jin, Yanhui Che, Dan Huang, Jiechen Wang, Meichun Zhao and Guangyu Sun
Forests 2019, 10(4), 312; https://0-doi-org.brum.beds.ac.uk/10.3390/f10040312 - 05 Apr 2019
Cited by 21 | Viewed by 4155
Abstract
Nitrogen dioxide (NO2) is recognized as a toxic gaseous air pollutant. However, atmospheric NO2 can be absorbed by plant leaves and subsequently participate in plant nitrogen metabolism. The metabolism of atmospheric NO2 utilizes and consumes the light energy that [...] Read more.
Nitrogen dioxide (NO2) is recognized as a toxic gaseous air pollutant. However, atmospheric NO2 can be absorbed by plant leaves and subsequently participate in plant nitrogen metabolism. The metabolism of atmospheric NO2 utilizes and consumes the light energy that leaves absorb. As such, it remains unclear whether the consumption of photosynthetic energy through nitrogen metabolism can decrease the photosynthetic capacity of plant leaves or not. In this study, we fumigated mulberry (Morus alba L.) plants with 4 μL·L−1 NO2 and analyzed the distribution of light energy absorbed by plants in NO2 metabolism using gas exchange and chlorophyll a fluorescence technology, as well as biochemical methods. NO2 fumigation enhanced the nitrogen metabolism of mulberry leaves, improved the photorespiration rate, and consumed excess light energy to protect the photosynthetic apparatus. Additionally, the excess light energy absorbed by the photosystem II reaction center in leaves of mulberry was dissipated in the form of heat dissipation. Thus, light energy was absorbed more efficiently in photosynthetic carbon assimilation in mulberry plants fumigated with 4 μL·L−1 NO2, which in turn increased the photosynthetic efficiency of mulberry leaves. Full article
(This article belongs to the Special Issue Relationship between Forest Ecophysiology and Environment)
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12 pages, 2910 KiB  
Article
Leaf Age Compared to Tree Age Plays a Dominant Role in Leaf δ13C and δ15N of Qinghai Spruce (Picea crassifolia Kom.)
by Caijuan Li, Bo Wang, Tuo Chen, Guobao Xu, Minghui Wu, Guoju Wu and Jinxiu Wang
Forests 2019, 10(4), 310; https://0-doi-org.brum.beds.ac.uk/10.3390/f10040310 - 04 Apr 2019
Cited by 4 | Viewed by 2424
Abstract
Leaf stable isotope compositions (δ13C and δ15N) are influenced by various abiotic and biotic factors. Qinghai spruce (Picea crassifolia Kom.) as one of the dominant tree species in Qilian Mountains plays a key role in the ecological stability [...] Read more.
Leaf stable isotope compositions (δ13C and δ15N) are influenced by various abiotic and biotic factors. Qinghai spruce (Picea crassifolia Kom.) as one of the dominant tree species in Qilian Mountains plays a key role in the ecological stability of arid region in the northwest of China. However, our knowledge of the relative importance of multiple factors on leaf δ13C and δ15N remains incomplete. In this work, we investigated the relationships of δ13C and δ15N to leaf age, tree age and leaf nutrients to examine the patterns and controls of leaf δ13C and δ15N variation of Picea crassifolia. Results showed that 13C and 15N of current-year leaves were more enriched than older ones at each tree age level. There was no significant difference in leaf δ13C values among trees of different ages, while juvenile trees (<50 years old) were 15N depleted compared to middle-aged trees (50–100 years old) at each leaf age level except for 1-year-old leaves. Meanwhile, relative importance analysis has demonstrated that leaf age was one of the most important indicators for leaf δ13C and δ15N. Moreover, leaf N concentrations played a dominant role in the variations of δ13C and δ15N. Above all, these results provide valuable information on the eco-physiological responses of P. crassifolia in arid and semi-arid regions. Full article
(This article belongs to the Special Issue Relationship between Forest Ecophysiology and Environment)
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