Periodic Reporting for period 1 - SYMBIONIX (Quantifying and upscaling nitrogen fixation in pristine ecosystems: Uncovering the climatic, ecological, and molecular control mechanisms)
Reporting period: 2021-02-01 to 2022-07-31
Plant productivity in boreal forests and tropical cloud forests is limited by the generally low availability of soil nutrients, primarily nitrogen (N), and these ecosystems are also the most vulnerable systems to climate change. Mosses account for a large fraction of ecosystem productivity in these habitats; and most of them are colonized by N2-fixing cyanobacteria, thereby providing plant-available N to the ecosystem. Despite this key role, critical knowledge gaps exist. For instance, the climatic controls of moss-associated N2 fixation are severely understudied, limiting our capability to predict climate change effects on this fundamental ecosystem function. Further, it is unknown whether mosses and associated N2 fixers share a mutualistic (both partners benefit) or parasitic (one partner benefits at the expense of the other) relationship. Yet, the balance of this association is crucial for maintaining ecosystem productivity. Current ecosystem models do not incorporate moss-associated N2 fixation, and thereby, significantly underestimate ecosystem productivity. In SYMBIONIX, we will combine field, laboratory and modelling approaches to fill these knowledge gaps in four interlinked Research Tracks (RT) by addressing four objectives:
RT1 Climatic Controls: To identify the climatic controls of N2 fixation in mosses from contrasting ecosystems: boreal forests and tropical cloud forests.
RT2 Molecular Controls: To ascertain the molecular traits defining the degree of mutualism or parasitism in moss-cyanobacteria associations using comparative transcriptomics.
RT3 Cellular Controls: To determine the nutrient exchange between moss and cyanobacteria using nanoSIMS (nano scale secondary ion mass spectrometry).
RT4 Synthesis: To model ecosystem N input via N2 fixation in boreal forests and tropical cloud forests.
RT1 Climatic Controls: To identify the climatic controls of N2 fixation in mosses from contrasting ecosystems: boreal forests and tropical cloud forests.
RT2 Molecular Controls: To ascertain the molecular traits defining the degree of mutualism or parasitism in moss-cyanobacteria associations using comparative transcriptomics.
RT3 Cellular Controls: To determine the nutrient exchange between moss and cyanobacteria using nanoSIMS (nano scale secondary ion mass spectrometry).
RT4 Synthesis: To model ecosystem N input via N2 fixation in boreal forests and tropical cloud forests.
During the first reporting period of the action, we have accomplished:
1) First sampling campaign completed in Northern Sweden: Moss samples were collected along an elevation gradient as well as in field experiments of nutrient additions to assess nitrogen fixation and bacterial community responses to different temperatures, precipitation and nutrient availability (research track 1). The obtained data is being analysed and written up for publication in a scientific journal
2) First sampling campaign completed in Costa Rica: we have established field sites along elevation gradients as well as nutrient addition plots in cloud forests. Moss and soil samples have been collected and are currently being analysed (research track 1).
https://www.biosfaere.org/costa-rica. These sites will be revisited in early 2023.
3) Publication of (a) an invited review article on the controls of nitrogen fixation in mosses as well as on (b) the effects on extreme freeze-thaw cycles on nitrogen fixation in mosses from different ecosystems.
Together with postdoctoral researcher Danillo Alvarenga, we have now established protocols for growing cyanobacteria and mosses independent of each other. This is a pre-requisite for research track 2.
1) First sampling campaign completed in Northern Sweden: Moss samples were collected along an elevation gradient as well as in field experiments of nutrient additions to assess nitrogen fixation and bacterial community responses to different temperatures, precipitation and nutrient availability (research track 1). The obtained data is being analysed and written up for publication in a scientific journal
2) First sampling campaign completed in Costa Rica: we have established field sites along elevation gradients as well as nutrient addition plots in cloud forests. Moss and soil samples have been collected and are currently being analysed (research track 1).
https://www.biosfaere.org/costa-rica. These sites will be revisited in early 2023.
3) Publication of (a) an invited review article on the controls of nitrogen fixation in mosses as well as on (b) the effects on extreme freeze-thaw cycles on nitrogen fixation in mosses from different ecosystems.
Together with postdoctoral researcher Danillo Alvarenga, we have now established protocols for growing cyanobacteria and mosses independent of each other. This is a pre-requisite for research track 2.
Boreal as well as tropical ecosystems are amongst the most vulnerable systems to climate change, which threatens a wide range of critical ecosystem services provided by these ecosystems as repositories of carbon and endangered species. This renders immediate assessments of climate change effects on these systems necessary and urgent. The results of SYMBIONIX will enable us to define the role of moss-cyanobacteria associations for the N cycle in a future climate, with fundamental implications for ecosystem productivity.
Progress in ecosystem research is often hampered by our lack of understanding of how limiting factors vary markedly across scales. SYMBIONIX offers the novel opportunity to combine biogeochemistry with ecology across scales, providing a break-through in ecosystem research. I will apply specific complementary methods and cutting-edge approaches when combining the RTs that ensures previously unachievable progress. Here, I will uniquely interlink a key ecosystem function (RT1) to its molecular (RT2) and ecological underpinnings (RT3). A synthesis of these RT’s will be accomplished via the parameterization and validation of current global circulation models (RT4). By assessing the molecular traits of moss-cyanobacteria associations, and functionally verifying these molecular mechanisms with the nutrient transfer between moss and colonizing cyanobacteria, my research group will undertake the first comprehensive attempt to place them along the mutualism-parasitism continuum. Further, by assessing the effects of abiotic factors (N availability) on the nutrient trade between moss and cyanobacteria, I can reveal how the balance between the partners is affected by N availability. This will also enable us to predict how the degree of mutualism or parasitism between moss and cyanobacteria will be affected by increased N input to pristine ecosystems. A decoupling of nutrient exchange mutualisms via increased N input may affect the entire ecosystem N budget and consequently, ecosystem productivity. In addition, the identification of “symbiosis genes” can aid in freeing crop production from N rich fertilizer use while enhancing yield.
Current ecosystem circulation models do not incorporate moss-associated N2 fixation, thereby misrepresenting ecosystem N inputs. Consequently, my group will offer a significant revision of major global circulation models (EC-Earth) via LPJ-GUESS. By being incorporated into an Earth system model that will participate in the international endeavour to inform the next IPCC Assessment, the fundamental science insights generated from this project will have a direct pathway of impact. Thus, the results of this project will have relevance for international policy advice on climate change. Furthermore, by modelling the resource optimization of moss-associated N2 fixation, my research team can estimate where and under which conditions N2 fixation in mosses occurs. This will facilitate focussed search in unexplored systems, which could lead to the discovery of N2 fixation in ecosystem types and areas that have been thought to lack any N2 fixation capabilities to date.
More specifically, we will for the first time assess nitrogen fixation in mosses in tropical cloud forests, link their activity to community structure and determine climate change effects on nitrogen fixation. These will be compared to mosses from Northern, cold ecosystems.
We further fill crucial knowledge gaps on nutrient limitation of nitrogen fixation across ecosystems (artic, tropics), and identify the role of mosses for ecosystem nitrogen pools.
The obtained data will be crucial in revising current ecosystem nutrient models.
Progress in ecosystem research is often hampered by our lack of understanding of how limiting factors vary markedly across scales. SYMBIONIX offers the novel opportunity to combine biogeochemistry with ecology across scales, providing a break-through in ecosystem research. I will apply specific complementary methods and cutting-edge approaches when combining the RTs that ensures previously unachievable progress. Here, I will uniquely interlink a key ecosystem function (RT1) to its molecular (RT2) and ecological underpinnings (RT3). A synthesis of these RT’s will be accomplished via the parameterization and validation of current global circulation models (RT4). By assessing the molecular traits of moss-cyanobacteria associations, and functionally verifying these molecular mechanisms with the nutrient transfer between moss and colonizing cyanobacteria, my research group will undertake the first comprehensive attempt to place them along the mutualism-parasitism continuum. Further, by assessing the effects of abiotic factors (N availability) on the nutrient trade between moss and cyanobacteria, I can reveal how the balance between the partners is affected by N availability. This will also enable us to predict how the degree of mutualism or parasitism between moss and cyanobacteria will be affected by increased N input to pristine ecosystems. A decoupling of nutrient exchange mutualisms via increased N input may affect the entire ecosystem N budget and consequently, ecosystem productivity. In addition, the identification of “symbiosis genes” can aid in freeing crop production from N rich fertilizer use while enhancing yield.
Current ecosystem circulation models do not incorporate moss-associated N2 fixation, thereby misrepresenting ecosystem N inputs. Consequently, my group will offer a significant revision of major global circulation models (EC-Earth) via LPJ-GUESS. By being incorporated into an Earth system model that will participate in the international endeavour to inform the next IPCC Assessment, the fundamental science insights generated from this project will have a direct pathway of impact. Thus, the results of this project will have relevance for international policy advice on climate change. Furthermore, by modelling the resource optimization of moss-associated N2 fixation, my research team can estimate where and under which conditions N2 fixation in mosses occurs. This will facilitate focussed search in unexplored systems, which could lead to the discovery of N2 fixation in ecosystem types and areas that have been thought to lack any N2 fixation capabilities to date.
More specifically, we will for the first time assess nitrogen fixation in mosses in tropical cloud forests, link their activity to community structure and determine climate change effects on nitrogen fixation. These will be compared to mosses from Northern, cold ecosystems.
We further fill crucial knowledge gaps on nutrient limitation of nitrogen fixation across ecosystems (artic, tropics), and identify the role of mosses for ecosystem nitrogen pools.
The obtained data will be crucial in revising current ecosystem nutrient models.