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Wang X, Chen L, Zhang H, Liu P, Shang X, Wang F, Zhang Z, Zhao J, Sun M, Chen J, Zhang J. Insect herbivory on woody broadleaf seedlings along a subtropical elevational gradient supports the resource concentration hypothesis. AMERICAN JOURNAL OF BOTANY 2024; 111:e16355. [PMID: 38831659 DOI: 10.1002/ajb2.16355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Revised: 04/07/2024] [Accepted: 04/09/2024] [Indexed: 06/05/2024]
Abstract
PREMISE Theories of plant-herbivore interactions hold that seedlings are more vulnerable to herbivory in warmer and more stable climates at lower elevations. Hypotheses of plant apparency, resource concentration, and resource availability have been proposed to explain variability in leaf herbivory. However, seasonal differences in the effects of these hypotheses on leaf herbivory on seedlings remain unclear. METHODS We evaluated the three herbivory hypotheses by comparing the percentage and frequency of leaf herbivory in understory broadleaf seedlings in a subtropical forest in May (spring) and October (autumn) along an elevational gradient (290-1370 m a.s.l.). In total, we measured 2890 leaves across 696 seedlings belonging to 95 species and used beta regressions to test the effects of plant apparency (e.g., leaf area, seedling height), resource concentration (e.g., plant species diversity), and resource availability (e.g., canopy openness, soil available N and P) on leaf herbivory. RESULTS Seedlings exhibited unimodal patterns of leaf herbivory along elevation, with drivers of leaf herbivory varying by the month. Variation in the frequency of leaf herbivory was best explained by the resource concentration hypothesis (e.g., plant species diversity) in both months, and herbivory was lower on seedlings in sites with higher plant diversity. Plant apparency hypothesis (e.g., leaf area, seedling height) was weakly supported only in spring, and the evidence for resource availability hypothesis (e.g., canopy openness, soil nutrients) was mixed. CONCLUSIONS This study supports the resource concentration hypothesis and reveals the importance of seasonal difference on understanding leaf herbivory patterns and the drivers of plant diversity in subtropical forests.
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Affiliation(s)
- Xiaoran Wang
- Center for Global Change and Complex Ecosystems, Zhejiang Tiantong Forest Ecosystem National Observation and Research Station, School of Ecological and Environmental Sciences, East China Normal University, Shanghai, 200241, China
- Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, China
| | - Lin Chen
- Administration of Guanshan National Nature Reserve, Yichun, 336300, China
| | - Hongwei Zhang
- Center for Global Change and Complex Ecosystems, Zhejiang Tiantong Forest Ecosystem National Observation and Research Station, School of Ecological and Environmental Sciences, East China Normal University, Shanghai, 200241, China
| | - Pengcheng Liu
- Center for Global Change and Complex Ecosystems, Zhejiang Tiantong Forest Ecosystem National Observation and Research Station, School of Ecological and Environmental Sciences, East China Normal University, Shanghai, 200241, China
| | - Xiaofan Shang
- Center for Global Change and Complex Ecosystems, Zhejiang Tiantong Forest Ecosystem National Observation and Research Station, School of Ecological and Environmental Sciences, East China Normal University, Shanghai, 200241, China
| | - Fang Wang
- Center for Global Change and Complex Ecosystems, Zhejiang Tiantong Forest Ecosystem National Observation and Research Station, School of Ecological and Environmental Sciences, East China Normal University, Shanghai, 200241, China
| | - Zhaochen Zhang
- Lushan Botanical Garden, Chinese Academy of Sciences, Jiujiang, 332900, China
| | - Jingchao Zhao
- Center for Global Change and Complex Ecosystems, Zhejiang Tiantong Forest Ecosystem National Observation and Research Station, School of Ecological and Environmental Sciences, East China Normal University, Shanghai, 200241, China
| | - Mufan Sun
- Center for Global Change and Complex Ecosystems, Zhejiang Tiantong Forest Ecosystem National Observation and Research Station, School of Ecological and Environmental Sciences, East China Normal University, Shanghai, 200241, China
| | - Junhong Chen
- Center for Global Change and Complex Ecosystems, Zhejiang Tiantong Forest Ecosystem National Observation and Research Station, School of Ecological and Environmental Sciences, East China Normal University, Shanghai, 200241, China
| | - Jian Zhang
- Center for Global Change and Complex Ecosystems, Zhejiang Tiantong Forest Ecosystem National Observation and Research Station, School of Ecological and Environmental Sciences, East China Normal University, Shanghai, 200241, China
- Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, China
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Kharel B, Rusalepp L, Bhattarai B, Kaasik A, Kupper P, Lutter R, Mänd P, Rohula-Okunev G, Rosenvald K, Tullus A. Effects of air humidity and soil moisture on secondary metabolites in the leaves and roots of Betula pendula of different competitive status. Oecologia 2023:10.1007/s00442-023-05388-9. [PMID: 37246972 DOI: 10.1007/s00442-023-05388-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Accepted: 05/19/2023] [Indexed: 05/30/2023]
Abstract
Plant secondary metabolites (PSMs) defend plants against abiotic stresses, including those caused by climate change and against biotic stresses, such as herbivory and competition. There is a trade-off between allocating available carbon to growth and defence in stressful environments. However, our knowledge about trade-off is limited, especially when abiotic and biotic stresses co-occur. We aimed to understand the combined effect of increasing precipitation and humidity, the tree's competitive status, and canopy position on leaf secondary metabolites (LSMs) and fine root secondary metabolites (RSMs) in Betula pendula. We sampled 8-year-old B. pendula trees growing in the free air humidity manipulation (FAHM) experimental site, where treatments included elevated relative air humidity and elevated soil moisture. A high-performance liquid chromatography-quadrupole-time of flight mass spectrometer (HPLC-qTOF-MS) was used to analyse secondary metabolites. Our results showed accumulation of LSM depends on the canopy position and competitive status. Flavonoids (FLA), dihydroxybenzoic acids (HBA), jasmonates (JA) and terpene glucosides (TG) were higher in the upper canopy, and FLA, monoaryl compounds (MAR) and sesquiterpenoids (ST) were higher in dominant trees. The FAHM treatments had a more distinct effect on RSM than on LSM. The RSMs were lower in elevated air humidity and soil moisture conditions than in control conditions. The RSM content depended on the competitive status and was higher in suppressed trees. Our study suggests that young B. pendula will allocate similar amounts of carbon to constitutive chemical leaf defence, but a lower amount to root defence (per fine root biomass) under higher humidity.
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Affiliation(s)
- Bikash Kharel
- Institute of Ecology and Earth Sciences, University of Tartu, Liivi 2, 50409, Tartu, Estonia.
| | - Linda Rusalepp
- Institute of Ecology and Earth Sciences, University of Tartu, Liivi 2, 50409, Tartu, Estonia
- Institute of Veterinary Medicine and Animal Sciences, Estonian University of Life Sciences, Kreutzwaldi 62, 51006, Tartu, Estonia
| | - Biplabi Bhattarai
- Institute of Ecology and Earth Sciences, University of Tartu, Liivi 2, 50409, Tartu, Estonia
| | - Ants Kaasik
- Institute of Ecology and Earth Sciences, University of Tartu, Liivi 2, 50409, Tartu, Estonia
| | - Priit Kupper
- Institute of Ecology and Earth Sciences, University of Tartu, Liivi 2, 50409, Tartu, Estonia
| | - Reimo Lutter
- Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, Kreutzwaldi 5, 51006, Tartu, Estonia
| | - Pille Mänd
- Institute of Ecology and Earth Sciences, University of Tartu, Liivi 2, 50409, Tartu, Estonia
| | - Gristin Rohula-Okunev
- Institute of Ecology and Earth Sciences, University of Tartu, Liivi 2, 50409, Tartu, Estonia
| | - Katrin Rosenvald
- Institute of Ecology and Earth Sciences, University of Tartu, Liivi 2, 50409, Tartu, Estonia
| | - Arvo Tullus
- Institute of Ecology and Earth Sciences, University of Tartu, Liivi 2, 50409, Tartu, Estonia
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Ziaja D, Müller C. Intraspecific chemodiversity provides plant individual- and neighbourhood-mediated associational resistance towards aphids. FRONTIERS IN PLANT SCIENCE 2023; 14:1145918. [PMID: 37082343 PMCID: PMC10111025 DOI: 10.3389/fpls.2023.1145918] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Accepted: 03/06/2023] [Indexed: 05/03/2023]
Abstract
Some plant species express an extraordinarily high intraspecific diversity in phytochemicals (= chemodiversity). As discussed for biodiversity, higher chemodiversity may provide better protection against environmental stress, including herbivory. However, little is known about whether the resistance of a plant individual towards herbivores is mostly governed by its own chemodiversity or by associational resistance provided by conspecific neighbours. To investigate the role of chemodiversity in plant-aphid interactions, we used the Asteraceae Tanacetum vulgare, whose individuals differ pronouncedly in the composition of leaf terpenoids, forming distinct chemotypes. Plants were set up in a field consisting of plots containing five individuals of either the same or different chemotypes. Presence of winged aphids, indicating attraction, and abundance of winged and unwinged aphids, indicating fitness, were counted weekly on each plant. During the peak abundance of aphids, leaf samples were taken from all plants for re-analyses of the terpenoid composition and quantification of terpenoid chemodiversity, calculated on an individual plant (Shannon index, Hsind, also considered as α-chemodiversity) and plot level (Hsplot, = β-chemodiversity). Aphid attraction was neither influenced by chemotype nor plot-type. The real-time odour environment may be very complex in this setting, impeding clear preferences. In contrast, the abundance was affected by both chemotype and plot-type. On average, more Uroleucon tanaceti aphids were found on plants of two of the chemotypes growing in homogenous compared to heterogenous plots, supporting the associational resistance hypothesis. For Macrosiphoniella tanacetaria aphids, the probability of presence differed between plot-types on one chemotype. Terpenoid chemodiversity expressed as a gradient revealed negative Hsplot effects on U. tanaceti, but a positive correlation of Hsind with M. tanacetaria abundance. Aphids of M. fuscoviride were not affected by any level of chemodiversity. In conclusion, this study shows that not only the chemotype and chemodiversity of individual plants but also that of conspecific neighbours can influence certain plant-herbivore interactions. These effects are highly specific with regard to the plant chemotype and differ between aphid species and their morphs (winged vs. unwinged). Furthermore, our results highlight the importance of analysing chemodiversity at different levels.
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Galmán A, Vázquez‐González C, Röder G, Castagneyrol B. Interactive effects of tree species composition and water availability on growth and direct and indirect defences in
Quercus ilex. OIKOS 2022. [DOI: 10.1111/oik.09125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Andrea Galmán
- Misión Biológica de Galicia, National Spanish Research Council (CSIC) Pontevedra Spain
- Inst. of Biology/Geobotany and Botanical Garden, Martin Luther Univ. Halle‐Wittenberg Germany
| | - Carla Vázquez‐González
- Misión Biológica de Galicia, National Spanish Research Council (CSIC) Pontevedra Spain
- Dept of Ecology and Evolutionary Biology, Univ. of California Irvine CA USA
| | - Gregory Röder
- Inst. of Biology, Univ. of Neuchâtel Neuchâtel Switzerland
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Tullus A, Rusalepp L, Lutter R, Rosenvald K, Kaasik A, Rytter L, Kontunen-Soppela S, Oksanen E. Climate and Competitive Status Modulate the Variation in Secondary Metabolites More in Leaves Than in Fine Roots of Betula pendula. FRONTIERS IN PLANT SCIENCE 2021; 12:746165. [PMID: 34899775 PMCID: PMC8655902 DOI: 10.3389/fpls.2021.746165] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Accepted: 11/04/2021] [Indexed: 06/01/2023]
Abstract
Plant secondary metabolites have many important functions; they also determine the productivity and resilience of trees under climate change. The effects of environmental factors on secondary metabolites are much better understood in above-ground than in below-ground part of the tree. Competition is a crucial biotic stress factor, but little is known about the interaction effect of climate and competition on the secondary chemistry of trees. Moreover, competition effect is usually overlooked when analyzing the sources of variation in the secondary chemistry. Our aim was to clarify the effects of competitive status, within-crown light environment, and climate on the secondary chemistry of silver birch (Betula pendula Roth). We sampled leaves (from upper and lower crown) and fine roots from competitively dominant and suppressed B. pendula trees in plantations along a latitudinal gradient (56-67° N) in Fennoscandia, with mean annual temperature (MAT) range: -1 to 8°C. Secondary metabolites in leaves (SML) and fine roots (SMFR) were determined with an HPLC-qTOF mass spectrometer. We found that SML content increased significantly with MAT. The effect of competitive stress on SML strengthened in colder climates (MAT<4°C). Competition and shade initiated a few similar responses in SML. SMFR varied less with MAT. Suppressed trees allocated relatively more resources to SML in warmer climates and to SMFR in colder ones. Our study revealed that the content and profile of secondary metabolites (mostly phenolic defense compounds and growth regulators) in leaves of B. pendula varied with climate and reflected the trees' defense requirements against herbivory, exposure to irradiance, and competitive status (resource supply). The metabolic profile of fine roots reflected, besides defense requirements, also different below-ground competition strategies in warmer and colder climates. An increase in carbon assimilation to secondary compounds can be expected at northern latitudes due to climate change.
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Affiliation(s)
- Arvo Tullus
- Institute of Ecology and Earth Sciences, University of Tartu, Tartu, Estonia
| | - Linda Rusalepp
- Institute of Ecology and Earth Sciences, University of Tartu, Tartu, Estonia
- Institute of Veterinary Medicine and Animal Sciences, Estonian University of Life Sciences, Tartu, Estonia
| | - Reimo Lutter
- Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, Tartu, Estonia
| | - Katrin Rosenvald
- Institute of Ecology and Earth Sciences, University of Tartu, Tartu, Estonia
| | - Ants Kaasik
- Institute of Ecology and Earth Sciences, University of Tartu, Tartu, Estonia
| | | | - Sari Kontunen-Soppela
- Department of Environmental and Biological Sciences, University of Eastern Finland, Joensuu, Finland
| | - Elina Oksanen
- Department of Environmental and Biological Sciences, University of Eastern Finland, Joensuu, Finland
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