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McDermott A. Climate change is drying out canopy plants-that could mean less water for the entire rainforest. Proc Natl Acad Sci U S A 2024; 121:e2415456121. [PMID: 39167599 PMCID: PMC11363270 DOI: 10.1073/pnas.2415456121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/23/2024] Open
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Chen XZ, Hogan JA, Wang CP, Wang PL, Lin TC. Responses of a common tropical epiphyte, Asplenium nidus, to changes in water and nutrient availability. AOB PLANTS 2023; 15:plad076. [PMID: 38046406 PMCID: PMC10689150 DOI: 10.1093/aobpla/plad076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/26/2023] [Accepted: 11/08/2023] [Indexed: 12/05/2023]
Abstract
Epiphytes are highly dependent on atmospheric inputs of water and nutrients. Reductions in water availability associated with warming and climate change and continual atmospheric nitrogen (N) deposition can affect plant growth but few studies have evaluated the effects of changes in both water and nutrient availabilities on epiphytes. We experimentally tested whether epiphyte growth is more water- or nutrient-limited, if nutrient limitation was stronger for nitrogen or phosphorus, and whether nutrient limitation interacts with water availability. We applied watering (high and low) and nutrient addition (control, +N, +P, +N+P) treatments to greenhouse-grown Asplenium nidus, a common epiphytic fern found in many tropical and subtropical wet forests. We measured leaf area production and leaf elemental concentrations to assess how A. nidus growth and physiology respond to changes in water and nutrient availabilities. We found that leaf growth of A. nidus was more affected by water availability than nutrient addition and the effect of adding nutrients was not fully realized under low-water availability. Among the different nutrient treatments, +N+P had the greatest effects on A. nidus growth and physiology in both watering treatments. Watering treatment changed leaf elemental concentrations but not their ratios (i.e. C:N and N:P). Nutrient addition altered C:N and N:P ratios and increased the concentration of the added elements in leaves, with more pronounced increases in the high-watering treatment. We conclude that the growth of A. nidus is more water- than nutrient-limited. When nutrient limitation occurs (i.e. under high-water availability), nutrient co-limitation is stronger than limitation by N or P alone. This result taken together with studies of other epiphytes suggests greater water than nutrient limitation is likely widespread among epiphytic plants. The limited effects of nutrient addition in the low-water treatment suggest that the effect of atmospheric N deposition on epiphyte growth will be limited when water availability is low.
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Affiliation(s)
- Xiao-Zhen Chen
- Department of Life Science, National Taiwan Normal University, Taipei 11677, Taiwan
| | - J Aaron Hogan
- Department of Biology, University of Florida, Gainesville, FL 32611, USA
| | - Chiao-Ping Wang
- Silviculture Division, Taiwan Forestry Research Institute, Taipei 10066, Taiwan
| | - Pei-Ling Wang
- Institute of Oceanography, National Taiwan University, Taipei 10617, Taiwan
| | - Teng-Chiu Lin
- Department of Life Science, National Taiwan Normal University, Taipei 11677, Taiwan
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Zotz G, Andrade JL, Einzmann HJR. CAM plants: their importance in epiphyte communities and prospects with global change. ANNALS OF BOTANY 2023; 132:685-698. [PMID: 36617243 PMCID: PMC10799991 DOI: 10.1093/aob/mcac158] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 12/08/2022] [Accepted: 12/15/2022] [Indexed: 06/17/2023]
Abstract
BACKGROUND AND SCOPE The epiphytic life form characterizes almost 10 % of all vascular plants. Defined by structural dependence throughout their life and their non-parasitic relationship with the host, the term epiphyte describes a heterogeneous and taxonomically diverse group of plants. This article reviews the importance of crassulacean acid metabolism (CAM) among epiphytes in current climatic conditions and explores the prospects under global change. RESULTS AND CONCLUSIONS We question the view of a disproportionate importance of CAM among epiphytes and its role as a 'key innovation' for epiphytism but do identify ecological conditions in which epiphytic existence seems to be contingent on the presence of this photosynthetic pathway. Possibly divergent responses of CAM and C3 epiphytes to future changes in climate and land use are discussed with the help of experimental evidence, current distributional patterns and the results of several long-term descriptive community studies. The results and their interpretation aim to stimulate a fruitful discussion on the role of CAM in epiphytes in current climatic conditions and in altered climatic conditions in the future.
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Affiliation(s)
- Gerhard Zotz
- Functional Ecology Group, Institute of Biology and Environmental Sciences, Carl von Ossietzky University Oldenburg, Box 5634, D-26046 Oldenburg, Germany
- Smithsonian Tropical Research Institute, Box 0843-03092, Panama, Republic of Panama
| | - José Luis Andrade
- Unidad de Recursos Naturales, Centro de Investigación Científica de Yucatán, Calle 43 No. 130, Chuburná de Hidalgo, Mérida, Yucatán, Mexico
| | - Helena J R Einzmann
- Functional Ecology Group, Institute of Biology and Environmental Sciences, Carl von Ossietzky University Oldenburg, Box 5634, D-26046 Oldenburg, Germany
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Males J, Baksh-Comeau Y, Jaggernauth D, Ballah S, Paltoo S, Griffiths H. Epiphytic CAM bromeliads indicate vulnerability of tropical forest communities to climate change. ANNALS OF BOTANY 2023; 132:699-715. [PMID: 37897046 PMCID: PMC10799987 DOI: 10.1093/aob/mcad152] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 08/14/2023] [Accepted: 10/13/2023] [Indexed: 10/29/2023]
Abstract
BACKGROUND AND SCOPE Vascular epiphytes have a variety of mechanisms to trap and retain water, including crassulacean acid metabolism (CAM). Niche segregation was investigated for epiphytic bromeliads on the tropical Caribbean island of Trinidad, where habitats range from lowland deciduous forests to high-rainfall montane tropical forests, ~1000 m in elevation. METHODS Four tank-impounding bromeliad epiphytes in the genus Aechmea (Ae. aquilega, Ae. fendleri, Ae. nudicaulis and Ae. dichlamydea) with CAM were mapped across their distinct geographical and elevational zonations in northern Trinidad and Tobago. Species distribution modelling was used to determine environmental limitations for each species. Anatomical and physiological measurements included leaf succulence traits, gas exchange and CAM activity; hydraulic conductance and vulnerability; stomatal sensitivity and quantum yield responses to nocturnal temperature and long-term water deficits. KEY RESULTS A total of 2876 field observations identified the transitions between the lowland Ae. aquilega and montane Ae. fendleri, occurring >500 m a.s.l. at the drier western end of the Northern Mountain Range and at progressively lower elevations towards the wetter, eastern region. Anatomical and physiological sensitivities of gas exchange, CAM activity and water use, and responses to elevated nocturnal temperatures and drought, were markedly different for Ae. fendleri compared with Ae. aquilega or the ubiquitous Ae. nudicaulis. CONCLUSIONS The species distribution model highlighted the susceptibility of Ae. fendleri to a changing climate. For each species, physiological and anatomical traits were tailored to environmental tolerances, consistent with specialist or generalist niche preferences. Using Intergovernmental Panel on Climate Change scenarios, we predict that rapid rainfall and temperature changes will lead to the loss of Ae. fendleri and associated lower (and upper) montane forest communities from Trinidad, seriously impacting both biodiversity and critical ecosystem functions here and in other tropical island habitats. Epiphytic bromeliads act as markers for threatened communities, and their physiological tolerances represent key indicators of climate change impacts.
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Affiliation(s)
- Jamie Males
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK
| | - Yasmin Baksh-Comeau
- National Herbarium of Trinidad and Tobago, University of West Indies St Augustine Campus, Trinidad, Trinidad and Tobago
| | - Dan Jaggernauth
- National Herbarium of Trinidad and Tobago, University of West Indies St Augustine Campus, Trinidad, Trinidad and Tobago
| | - Shane Ballah
- National Herbarium of Trinidad and Tobago, University of West Indies St Augustine Campus, Trinidad, Trinidad and Tobago
| | - Shahada Paltoo
- National Herbarium of Trinidad and Tobago, University of West Indies St Augustine Campus, Trinidad, Trinidad and Tobago
| | - Howard Griffiths
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK
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Nadkarni NM. Complex consequences of disturbance on canopy plant communities of world forests: a review and synthesis. THE NEW PHYTOLOGIST 2023; 240:1366-1380. [PMID: 37817471 DOI: 10.1111/nph.19245] [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: 02/15/2023] [Accepted: 07/21/2023] [Indexed: 10/12/2023]
Abstract
Epiphytes and their associated biota are increasingly recognized as contributing to biodiversity and to filling critical ecosystem functions in world forests. However, the attributes that have made them successful in canopy environments also make them vulnerable to natural and human-induced disturbances. Drawing upon ecological frameworks to understand disturbance, I categorized and synthesized the drivers and the consequences of disturbances on epiphytic materials. Across all impacts, disturbance agents were significantly more likely to lead to negative, rather than positive, effects in both tropical and temperate locales. Significantly more studies reported negative effects on abundance, diversity, community composition and connectivity, but some studies showed that disturbances enhanced these attributes. Although particular disturbance agents did not differently influence individual consequences, they explained a significant portion of variation in aggregated totals. Surprisingly, relative to human disturbances, natural disturbances were more likely to lead to negative effects. Many studies provided recommendations for effective societal responses to mitigate negative impacts, such as retaining large, old trees in forestry operations, patch-clearing for epiphyte harvest, maximizing forest fragment size, using epiphytes as bioindicators of disturbance, and applying principles of community forestry to land management. Future actions should also include communication of these results to policymakers and land managers.
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Affiliation(s)
- Nalini M Nadkarni
- School of Biological Sciences, University of Utah, Salt Lake City, UT, 84112, USA
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Mata-Guel EO, Soh MCK, Butler CW, Morris RJ, Razgour O, Peh KSH. Impacts of anthropogenic climate change on tropical montane forests: an appraisal of the evidence. Biol Rev Camb Philos Soc 2023; 98:1200-1224. [PMID: 36990691 DOI: 10.1111/brv.12950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 03/08/2023] [Accepted: 03/10/2023] [Indexed: 03/31/2023]
Abstract
In spite of their small global area and restricted distributions, tropical montane forests (TMFs) are biodiversity hotspots and important ecosystem services providers, but are also highly vulnerable to climate change. To protect and preserve these ecosystems better, it is crucial to inform the design and implementation of conservation policies with the best available scientific evidence, and to identify knowledge gaps and future research needs. We conducted a systematic review and an appraisal of evidence quality to assess the impacts of climate change on TMFs. We identified several skews and shortcomings. Experimental study designs with controls and long-term (≥10 years) data sets provide the most reliable evidence, but were rare and gave an incomplete understanding of climate change impacts on TMFs. Most studies were based on predictive modelling approaches, short-term (<10 years) and cross-sectional study designs. Although these methods provide moderate to circumstantial evidence, they can advance our understanding on climate change effects. Current evidence suggests that increasing temperatures and rising cloud levels have caused distributional shifts (mainly upslope) of montane biota, leading to alterations in biodiversity and ecological functions. Neotropical TMFs were the best studied, thus the knowledge derived there can serve as a proxy for climate change responses in under-studied regions elsewhere. Most studies focused on vascular plants, birds, amphibians and insects, with other taxonomic groups poorly represented. Most ecological studies were conducted at species or community levels, with a marked paucity of genetic studies, limiting understanding of the adaptive capacity of TMF biota. We thus highlight the long-term need to widen the methodological, thematic and geographical scope of studies on TMFs under climate change to address these uncertainties. In the short term, however, in-depth research in well-studied regions and advances in computer modelling approaches offer the most reliable sources of information for expeditious conservation action for these threatened forests.
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Affiliation(s)
- Erik O Mata-Guel
- School of Biological Sciences, University of Southampton, Highfield Campus, Southampton, SO17 1BJ, UK
| | - Malcolm C K Soh
- National Park Boards, 1 Cluny Road, Singapore, 259569, Singapore
| | - Connor W Butler
- School of Biological Sciences, University of Southampton, Highfield Campus, Southampton, SO17 1BJ, UK
| | - Rebecca J Morris
- School of Biological Sciences, University of Southampton, Highfield Campus, Southampton, SO17 1BJ, UK
| | - Orly Razgour
- Biosciences, University of Exeter, Exeter, EX4 4PS, UK
| | - Kelvin S-H Peh
- School of Biological Sciences, University of Southampton, Highfield Campus, Southampton, SO17 1BJ, UK
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Hu T, Liu WY, Wen HD, Song L, Zhang TT, Chen Q, Liu S. Vascular epiphyte populations with higher leaf nutrient concentrations showed weaker resilience to an extreme drought in a montane cloud forest. PLANT BIOLOGY (STUTTGART, GERMANY) 2023; 25:215-225. [PMID: 36208062 DOI: 10.1111/plb.13474] [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: 06/22/2022] [Accepted: 09/30/2022] [Indexed: 06/16/2023]
Abstract
Leaf stoichiometry can characterize plant ecological strategies and correlate with plant responses to climate change. The role of vascular epiphytes in the ecosystem processes of tropical and subtropical forest ecosystems cannot be ignored. Vascular epiphytes are very vulnerable to climate change, however, the relationship between the response of epiphytes to climate change and leaf stoichiometry is not well understood. We present data for 19 vascular epiphyte species that were collected during four consecutive censuses (in 2005, 2010, 2015, and 2020) over 15 years in a subtropical montane cloud forest. We assessed the relationships between the population dynamics and leaf stoichiometry of these vascular epiphytes. Experiencing an extreme drought, 14 of the 19 epiphyte species showed an obvious decrease in the number of individuals, and all species showed negative growth in the number of populations. Subsequently, the total number of individuals gradually recovered, increasing from 7,195 in 2010 to 10,121 in 2015, then to 13,667 in 2020. The increase in the number of vascular epiphyte individuals from 2010 to 2015 was significantly negatively correlated with leaf nitrogen and phosphorus concentration, and was significantly positively correlated with the leaf carbon-nitrogen ratio. Vascular epiphyte populations with higher leaf nutrient concentrations exhibited weaker resilience to the extreme drought, which demonstrated that a resource-conservative strategy was advantageous for the recovery of epiphyte populations. Our findings suggest that ecological stoichiometry can be a useful framework for forecasting the dynamics of vascular epiphyte populations in response to climate change.
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Affiliation(s)
- T Hu
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Yunnan, China
- University of Chinese Academy of Sciences, Beijing, China
| | - W Y Liu
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Yunnan, China
- Center for Plant Ecology, Core Botanical Gardens, Chinese Academy of Sciences, Xishuangbanna, China
| | - H D Wen
- National Field Scientific Observation and Research Station of Forest Ecosystem in Ailao Mountain, Yunnan, China
| | - L Song
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Yunnan, China
- Center for Plant Ecology, Core Botanical Gardens, Chinese Academy of Sciences, Xishuangbanna, China
| | - T T Zhang
- Henna University of Urban Construction, Pingdingshan, China
| | - Q Chen
- Life Sciences Institute, Guangxi Medical University, Nanning, China
| | - S Liu
- College of Life Sciences, Anhui Normal University, Wuhu, China
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Ferguson BN, Gotsch SG, Williams CB, Wilson H, Barnes CN, Dawson TE, Nadkarni NM. Variation in cloud immersion, not precipitation, drives leaf trait plasticity and water relations in vascular epiphytes during an extreme drought. AMERICAN JOURNAL OF BOTANY 2022; 109:550-563. [PMID: 35244206 DOI: 10.1002/ajb2.1833] [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: 05/10/2021] [Revised: 02/08/2022] [Accepted: 02/10/2022] [Indexed: 06/14/2023]
Abstract
PREMISE Epiphytes are abundant in ecosystems such as tropical montane cloud forests where low-lying clouds are often in contact with vegetation. Climate projections for these regions include more variability in rainfall and an increase in cloud base heights, which would lead to drier conditions in the soil and atmosphere. While recent studies have examined the effects of drought on epiphytic water relations, the influence that atmospheric moisture has, either alone or in combination with drought, on the health and performance of epiphyte communities remains unclear. METHODS We conducted a 10-week drought experiment on seven vascular epiphyte species in two shadehouses, one with warmer and drier conditions and another that was cooler and more humid. We measured water relations across control and drought-treatment groups and assessed functional traits of leaves produced during drought conditions to evaluate trait plasticity. RESULTS Epiphytes exposed to drought and drier atmospheric conditions had a significant reduction in stomatal conductance and leaf water potential and an increase in leaf dry matter. Nonsucculent epiphytes from the drier shadehouse had the greatest shifts in functional traits, whereas succulent epiphytes released stored leaf water to maintain water status. CONCLUSIONS Individuals in the drier shadehouse had a substantial reduction in performance, whereas drought-treated individuals that experienced cloud immersion displayed minimal changes in water status. Our results indicate that projected increases in the cloud base height will reduce growth and performance of epiphytic communities and that nonsucculent epiphytes may be particularly vulnerable.
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Affiliation(s)
- Briana N Ferguson
- Department of Biology, Franklin and Marshall College, Lancaster, PA, USA
| | - Sybil G Gotsch
- Department of Biology, Franklin and Marshall College, Lancaster, PA, USA
| | - Cameron B Williams
- Department of Biology, Franklin and Marshall College, Lancaster, PA, USA
- Cameron B. Williams, Channel Islands National Park, Ventura, CA, USA
| | - Hannah Wilson
- Department of Biology, Franklin and Marshall College, Lancaster, PA, USA
| | - Caitlin N Barnes
- Department of Biology, Franklin and Marshall College, Lancaster, PA, USA
| | - Todd E Dawson
- Department of Integrative Biology, University of California-Berkeley, Berkeley, CA, USA
| | - Nalini M Nadkarni
- Department of Biology, The University of Utah, Salt Lake City, UT, USA
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Mejia-Chang M, Reyes-Garcia C, Seibt U, Royles J, Meyer MT, Jones GD, Winter K, Arnedo M, Griffiths H. Leaf water δ 18O reflects water vapour exchange and uptake by C 3 and CAM epiphytic bromeliads in Panama. FUNCTIONAL PLANT BIOLOGY : FPB 2021; 48:732-742. [PMID: 34099101 DOI: 10.1071/fp21087] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Accepted: 04/20/2021] [Indexed: 05/27/2023]
Abstract
The distributions of CAM and C3 epiphytic bromeliads across an altitudinal gradient in western Panama were identified from carbon isotope (δ13C) signals, and epiphyte water balance was investigated via oxygen isotopes (δ18O) across wet and dry seasons. There were significant seasonal differences in leaf water (δ18Olw), precipitation, stored 'tank' water and water vapour. Values of δ18Olw were evaporatively enriched at low altitude in the dry season for the C3 epiphytes, associated with low relative humidity (RH) during the day. Crassulacean acid metabolism (CAM) δ18Olw values were relatively depleted, consistent with water vapour uptake during gas exchange under high RH at night. At high altitude, cloudforest locations, C3 δ18Olw also reflected water vapour uptake by day. A mesocosm experiment with Tillandsia fasciculata (CAM) and Werauhia sanguinolenta (C3) was combined with simulations using a non-steady-state oxygen isotope leaf water model. For both C3 and CAM bromeliads, δ18Olw became progressively depleted under saturating water vapour by day and night, although evaporative enrichment was restored in the C3 W. sanguinolenta under low humidity by day. Source water in the overlapping leaf base 'tank' was also modified by evaporative δ18O exchanges. The results demonstrate how stable isotopes in leaf water provide insights for atmospheric water vapour exchanges for both C3 and CAM systems.
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Affiliation(s)
- Monica Mejia-Chang
- Physiological Ecology Group, Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA, UK
| | - Casandra Reyes-Garcia
- Physiological Ecology Group, Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA, UK; and Unidad de Recursos Naturales, Centro de Investigación Científica de Yucatán, Calle 43 Num. 130 Churburná de Hidalgo, Mérida, 97200, México
| | - Ulli Seibt
- Physiological Ecology Group, Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA, UK; and Department of Atmospheric and Oceanic Sciences, UCLA, Los Angeles, CA, USA
| | - Jessica Royles
- Physiological Ecology Group, Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA, UK
| | - Moritz T Meyer
- Physiological Ecology Group, Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA, UK
| | - Glyn D Jones
- Physiological Ecology Group, Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA, UK
| | - Klaus Winter
- Smithsonian Tropical Research Institute, Apartado 0843-03092, Balboa, Republic of Panama
| | - Miquel Arnedo
- Departament de Biologia Evolutiva, Ecologia i Ciències Ambientals, Fac. Biologia, Universitat de Barcelona, Av. Diagonal 645, 08028 Barcelona, Spain
| | - Howard Griffiths
- Physiological Ecology Group, Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA, UK; and Corresponding author.
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