Concepts in empirical plant ecology

Körner, Christian

doi:10.1080/17550874.2018.1540021

Cited by 47 publications

(36 citation statements)

References 175 publications

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“…Lower-crown defoliation had no effect on primary and secondary growth and NSC content in genotype A, indicating that it was not affected by C shortage. Plant canopies can present high leaf area index values beyond saturation with no further contribution to C assimilation ( Thomas and Sadras, 2001 ; Weiner and Freckleton, 2010 ; Körner, 2018 ). Genotype A appeared to be saturated in terms of leaf area, even after defoliation.…”

Section: Discussionmentioning

confidence: 99%

“…Leaves located in upper and outer parts of a tree crown have larger photosynthetic capacity and higher amounts of nitrogen (N) stored in photosynthetic proteins, such as Rubisco and chlorophyll-binding polypeptides, compared with leaves in the lower part or interior of the crown ( Leuning et al , 1991 ; Camm, 1993 ; Ackerly, 1999 ; Millard and Grelet, 2010 ; Bresinsky et al , 2013 ). The foliage density required to maximize C uptake is commonly far exceeded in tree crowns, suggesting different roles for lower-crown foliage other than contributing to the net gain in C assimilation ( Thomas and Sadras, 2001 ; Hirose, 2005 ; Körner, 2018 ). Shaded leaves have been recognized to serve as nutrient and C stores for later resorption by younger leaves, and as a buffer in the case of foliage loss, especially in evergreen conifers ( Nambiar and Fife, 1987 ; Thomas and Sadras, 2001 ; Millard and Grelet, 2010 ; Hirose, 2012 ).…”

Section: Introductionmentioning

confidence: 99%

“…The imposition of C (source) limitation by defoliation is controversial and has not been proven per se . Most canopies are saturated in terms of light and photosynthesis ( Körner 2018 ). However, it has been suggested that under severe defoliation, C supply indeed becomes limiting ( Wiley and Helliker, 2012 ; Wiley et al , 2013 ; Palacio et al , 2014 ).…”

Section: Introductionmentioning

confidence: 99%

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No carbon limitation after lower crown loss in Pinus radiata

et al. 2020

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Background and Aims Biotic and abiotic stressors can cause different defoliation patterns within trees. Foliar pathogens of conifers commonly prefer older needles and infection with defoliation that progresses from the bottom crown to the top. The functional role of the lower crown of trees is a key question to address the impact of defoliation caused by foliar pathogens. Methods A 2 year artificial defoliation experiment was performed using two genotypes of grafted Pinus radiata to investigate the effects of lower-crown defoliation on carbon (C) assimilation and allocation. Grafts received one of the following treatments in consecutive years: control–control, control–defoliated, defoliated–control and defoliated–defoliated. Results No upregulation of photosynthesis either biochemically or through stomatal control was observed in response to defoliation. The root:shoot ratio and leaf mass were not affected by any treatment, suggesting prioritization of crown regrowth following defoliation. In genotype B, defoliation appeared to impose C shortage and caused reduced above-ground growth and sugar storage in roots, while in genotype A, neither growth nor storage was altered. Root C storage in genotype B decreased only transiently and recovered over the second growing season. Conclusions In genotype A, the contribution of the lower crown to the whole-tree C uptake appears to be negligible, presumably conferring resilience to foliar pathogens affecting the lower crown. Our results suggest that there is no C limitation after lower-crown defoliation in P. radiata grafts. Further, our findings imply genotype-specific defoliation tolerance in P. radiata.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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No carbon limitation after lower crown loss in Pinus radiata

et al. 2020

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“…Third, plant interactions can have important implications for ecological processes at different levels of organisation as well as at different temporal and spatial scales. These include effects on plant eco-physiology (Schöb et al 2014a;Körner 2018), demography (Verdú and Valiente-Banuet 2008), structure and diversity of communities (Butterfield et al 2013;Kikvidze et al 2015), and potentially even contributing to evolutionary diversity at the biome scale (Valiente-Banuet et al 2006). An adequate characterisation of plant networks in each of the three cases will inform us about the implications of biotic interactions in different ecological processes.…”

Section: Introductionmentioning

confidence: 99%

Perspectives for ecological networks in plant ecology

Losapio

Montesinos‐Navarro

Sáiz

2019

Plant Ecology & Diversity

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Background: Plant communities are usually characterised by species composition and abundance, but also underlie a multitude of complex interactions that we have only recently started unveiling. Yet, we are still far from understanding ecological and evolutionary processes shaping the network-level organisation of plant diversity, and to what extent these processes are specific to certain spatial scales or environments. Aims: Understanding the systemic mechanisms of plant-plant network assembly and their consequences for diversity patterns. Methods: We review recent methods and results of plant-plant networks. Results: We synthetize how plant-plant networks can help us to: (a) assess how competition and facilitation may balance each other through the network; (b) analyse the role of plantplant interactions beyond pairwise competition in structuring plant communities, and (c) forecast the ecological implications of complex species dependencies. We discuss pros and cons, assumptions and limitations of different approaches used for inferring plant-plant networks. Conclusions: We propose novel opportunities for advancing plant ecology by using ecological networks that encompass different ecological levels and spatio-temporal scales, and incorporate more biological information. Embracing networks of interactions among plants can shed new light on mechanisms driving evolution and ecosystem functioning, helping us to mitigate diversity loss.

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“…However, PNL under eCO 2 has only been confirmed in few cases (Norby 2011;Zähle 2014). Beginning with photosynthesis, CO 2 can stimulate a cascade of potential effects in an ecosystem, leading to an increase in plant growth and in belowground allocation (root growth) (Andresen et al 2016b;Körner 2018). Subsequently, increased rhizodeposition could stimulate organic matter decomposition (rhizosphere priming) and nutrient mineralization, leading to increased nutrient availability, to meet the extra nutrient demand (Dijkstra et al 2013;Kuzyakov 2015;Jilling et al 2018;Moreau et al 2019;Schleppi 2019).…”

Section: Introductionmentioning

confidence: 99%

Nitrogen dynamics after two years of elevated CO2 in phosphorus limited Eucalyptus woodland

et al. 2020

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It is uncertain how the predicted further rise of atmospheric carbon dioxide (CO2) concentration will affect plant nutrient availability in the future through indirect effects on the gross rates of nitrogen (N) mineralization (production of ammonium) and depolymerization (production of free amino acids) in soil. The response of soil nutrient availability to increasing atmospheric CO2 is particularly important for nutrient poor ecosystems. Within a FACE (Free-Air Carbon dioxide Enrichment) experiment in a native, nutrient poor Eucalyptus woodland (EucFACE) with low soil organic matter (≤ 3%), our results suggested there was no shortage of N. Despite this, microbial N use efficiency was high (c. 90%). The free amino acid (FAA) pool had a fast turnover time (4 h) compared to that of ammonium (NH4+) which was 11 h. Both NH4-N and FAA-N were important N pools; however, protein depolymerization rate was three times faster than gross N mineralization rates, indicating that organic N is directly important in the internal ecosystem N cycle. Hence, the depolymerization was the major provider of plant available N, while the gross N mineralization rate was the constraining factor for inorganic N. After two years of elevated CO2, no major effects on the pools and rates of the soil N cycle were found in spring (November) or at the end of summer (March). The limited response of N pools or N transformation rates to elevated CO2 suggest that N availability was not the limiting factor behind the lack of plant growth response to elevated CO2, previously observed at the site.

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Concepts in empirical plant ecology

Cited by 47 publications

References 175 publications

No carbon limitation after lower crown loss in Pinus radiata

No carbon limitation after lower crown loss in Pinus radiata

Perspectives for ecological networks in plant ecology

Nitrogen dynamics after two years of elevated CO2 in phosphorus limited Eucalyptus woodland

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