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The 'island effect' in terrestrial global change experiments: a problem with no solution?

Leuzinger S, Fatichi S, Cusens J, Körner C, Niklaus PA - AoB Plants (2015)

Bottom Line: Here, we discuss its implications in various global change experiments with plants.We also suggest ways to complement experiments using modelling approaches and observational studies.Ultimately, there is no obvious solution to deal with the island effect in field experiments and only models can provide an estimate of modification of responses by these feedbacks.

View Article: PubMed Central - PubMed

Affiliation: Institute for Applied Ecology New Zealand, School of Applied Sciences, Auckland University of Technology, Private Bag 92006, Auckland 1142, New Zealand sleuzing@aut.ac.nz.

No MeSH data available.


Related in: MedlinePlus

Potential feedback effects originating from an initial change in transpiration. In terrestrial global change experiments, these can turn into what we call ‘island effects’, depending on the considered spatial and temporal scale. At the lowest spatiotemporal scale (under the green arc), the island effect can be assumed to be zero, as the leaf boundary layer conditions are in fact influenced only by the respective leaf. The green arrows (1) represent first-order feedback effects, only leaf-level VPD is involved. Second-order feedback effects involve other factors such as cloud formation (2.1, yellow arrow), soil moisture (2.2, red arrow) or longer-term changes such as LAI or community composition (2.3, blue arrows).
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PLV092F2: Potential feedback effects originating from an initial change in transpiration. In terrestrial global change experiments, these can turn into what we call ‘island effects’, depending on the considered spatial and temporal scale. At the lowest spatiotemporal scale (under the green arc), the island effect can be assumed to be zero, as the leaf boundary layer conditions are in fact influenced only by the respective leaf. The green arrows (1) represent first-order feedback effects, only leaf-level VPD is involved. Second-order feedback effects involve other factors such as cloud formation (2.1, yellow arrow), soil moisture (2.2, red arrow) or longer-term changes such as LAI or community composition (2.3, blue arrows).

Mentions: Because the feedback loops associated with the island effect act across large spatial and temporal scales, the question of interest must be as follows: ‘what do we miss in an experiment due to the island effect?’ Admittedly, this question becomes almost infinitely complex and there is no definite answer, at least not from experiments. However, we can simplify the question by restricting ourselves to a given spatiotemporal scale (Fig. 2). All higher-order feedbacks missed in an experimentally treated vegetation island will have their origin in changes in transpiration caused by changes in gs. This is not quite true if long-term changes in LAI and community composition are considered, as those potentially entail changes in albedo, leaf energy balance and stand transpiration, irrespective of changes in gs. However, this long-term feedback can also arise from first-order changes in gs (see group 2.3), under which category they will be treated here.Figure 2.


The 'island effect' in terrestrial global change experiments: a problem with no solution?

Leuzinger S, Fatichi S, Cusens J, Körner C, Niklaus PA - AoB Plants (2015)

Potential feedback effects originating from an initial change in transpiration. In terrestrial global change experiments, these can turn into what we call ‘island effects’, depending on the considered spatial and temporal scale. At the lowest spatiotemporal scale (under the green arc), the island effect can be assumed to be zero, as the leaf boundary layer conditions are in fact influenced only by the respective leaf. The green arrows (1) represent first-order feedback effects, only leaf-level VPD is involved. Second-order feedback effects involve other factors such as cloud formation (2.1, yellow arrow), soil moisture (2.2, red arrow) or longer-term changes such as LAI or community composition (2.3, blue arrows).
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4584962&req=5

PLV092F2: Potential feedback effects originating from an initial change in transpiration. In terrestrial global change experiments, these can turn into what we call ‘island effects’, depending on the considered spatial and temporal scale. At the lowest spatiotemporal scale (under the green arc), the island effect can be assumed to be zero, as the leaf boundary layer conditions are in fact influenced only by the respective leaf. The green arrows (1) represent first-order feedback effects, only leaf-level VPD is involved. Second-order feedback effects involve other factors such as cloud formation (2.1, yellow arrow), soil moisture (2.2, red arrow) or longer-term changes such as LAI or community composition (2.3, blue arrows).
Mentions: Because the feedback loops associated with the island effect act across large spatial and temporal scales, the question of interest must be as follows: ‘what do we miss in an experiment due to the island effect?’ Admittedly, this question becomes almost infinitely complex and there is no definite answer, at least not from experiments. However, we can simplify the question by restricting ourselves to a given spatiotemporal scale (Fig. 2). All higher-order feedbacks missed in an experimentally treated vegetation island will have their origin in changes in transpiration caused by changes in gs. This is not quite true if long-term changes in LAI and community composition are considered, as those potentially entail changes in albedo, leaf energy balance and stand transpiration, irrespective of changes in gs. However, this long-term feedback can also arise from first-order changes in gs (see group 2.3), under which category they will be treated here.Figure 2.

Bottom Line: Here, we discuss its implications in various global change experiments with plants.We also suggest ways to complement experiments using modelling approaches and observational studies.Ultimately, there is no obvious solution to deal with the island effect in field experiments and only models can provide an estimate of modification of responses by these feedbacks.

View Article: PubMed Central - PubMed

Affiliation: Institute for Applied Ecology New Zealand, School of Applied Sciences, Auckland University of Technology, Private Bag 92006, Auckland 1142, New Zealand sleuzing@aut.ac.nz.

No MeSH data available.


Related in: MedlinePlus