Periodic Reporting for period 4 - IceCommunities (Reconstructing community dynamics and ecosystem functioning after glacial retreat)
Periodo di rendicontazione: 2022-10-01 al 2024-01-31
Glaciers are retreating all over the globe. Increasing areas are exposed and colonized by multiple organisms, but lack of global studies hampers a complete understanding of the future of recently deglaciated terrains. What will be the fate of these areas? How do animals, plants and microorganisms colonize them? How do they interact to perform successful colonization? Which are the processes determining colonization patterns? How does ecosystem functioning evolves through time? Until now, the complete reconstruction of soil communities was hampered by the complexity of identification of organisms, thus analyses at broad geographical and taxonomic scale have been so far impossible. IceCommunities combines innovative methods and a global approach to boost our understanding of the evolution of ecosystems in recently deglaciated areas. We are investigating chronosequences ranging from recently deglaciated terrains to late successional stages of soil pedogenesis, exploiting the power of environmental DNA metabarcoding.
IceCommunities produced an exhaustive reconstruction of biotic communities along glacier forelands over multiple mountain areas across the globe. This allows measuring the rate of colonization at an unprecedented detail. Information on assemblages is combined with analyses of soil, landscape and climate to identify the drivers of community changes. Furthermore, IceCommunities assesses the impact of eco-geographical factors (climate, regional pool of potential colonizers) on colonization. Finally, the analysis of functional traits allows reconstructing how functional diversity emerges during community formation, and how it scales to the functioning of food webs.
The results of the IceCommunities project allow to understand the overall mechanisms underlying the early dynamics of ecosystems emerging after glacier retreat, and identified strategies for the management of these ecosystems
IceCommunities produced an exhaustive reconstruction of biotic communities along glacier forelands over multiple mountain areas across the globe. This allows measuring the rate of colonization at an unprecedented detail. Information on assemblages is combined with analyses of soil, landscape and climate to identify the drivers of community changes. Furthermore, IceCommunities assesses the impact of eco-geographical factors (climate, regional pool of potential colonizers) on colonization. Finally, the analysis of functional traits allows reconstructing how functional diversity emerges during community formation, and how it scales to the functioning of food webs.
The results of the IceCommunities project allow to understand the overall mechanisms underlying the early dynamics of ecosystems emerging after glacier retreat, and identified strategies for the management of these ecosystems
- Through multiple field expeditions, we collected samples representative of glaciers all over the world (Fig. 1-3)
- We used the power of eDNA metabarcoding to obtain high-resolution measures of biodiversity in these areas
Environmental DNA (eDNA) is the DNA that can be extracted from environmental samples without isolating the remains of organisms. Environmental samples contain the eDNA of multiple organisms, that can be amplified, compared with reference databases and identified in a procedure named eDNA metabarcoding. We extracted eDNA from >1200 soil samples, and amplified it using primes targeting multiple components of biodiversity: bacteria, fungi, protists, plants and animals.
- We performed bioinformatic analyses: from sequences to biodiversity information.
Several methodological analyses enhanced the rigour of our study. We compared approaches for soil preservation to identify the most robust protocol (Guerrieri et al. 2020) and contributed to methodological essays describing the best practices for biodiversity analyses using metabarcoding (Chen & Ficetola 2019; Zinger et al. 2019; Ficetola & Taberlet 2023). We generated a huge amount of genomic data that required extensive bioinformatics analyses.
- We produced high-resolution data on the environmental features of glacier forelands, particularly climate, soil and vegetation.
We produced the first reconstruction at very high resolution of temperature in proglacial environments at the global scale. These data showed that glacier forelands are warming much faster than other mountain areas (Marta et al. 2023).
We performed multiple analyses of soil features, to identify properties that affect the development of communities, and confirmed the importance of these parameters for soil fauna. We also showed that soil organic matter increases with time in glacier forelands, but the patterns of soil development are different across areas of the world (Fig. 4; Khedim et al 2021).
- We measured the biodiversity of communities.
eDNA data allowed measuring the development of biodiversity. We detected >10000 taxonomic units of bacteria, fungi, protists, plants and animals. The diversity of all groups of organisms increased through time after glacier retreat, but differences between taxa and areas of the world are strong.
- We show that communities evolve through two distinct mechanisms: species addition and replacement, and the importance of these mechanisms varied over time.
Taxa addition dominated immediately after glacier retreat, while replacement became more important for late-successional communities (Fig. 5).
- We show that biotic interactions, particularly mutualisms, are extremely important to favour colonization.
We found strong relationships between plants and fungi (e.g. mycorrhizal fungi), even at the early stage of colonization. This indicates that interactions have a major role for biotic colonization (Carteron et al 2024; Fig. 6). These associations depends from the balance between multiple biotic and abiotic factors.
- We show that climatic differences between areas of the world have strong impacts on the development of biodiversity.
Colonization is faster in forelands with mild summer temperatures, particularly at the early stages after glacier retreat. The effects of climate on biotic colonization led to heterogeneous but predictable patterns around the world that can affect likely determine the overall ecosystem development (Guerrieri et al 2024; Fig. 7)
Overall, the project greatly contributed to improve our understanding of the impact of climate change on biodiversity.
From the scientific point of view, it resulted in a large number of papers by project members (29 accepted papers, including papers in Nature Ecology & Evolution, Nature Plants, Nature Communications…)
The project results have been disseminated with a large number of strategies, including scientific conferences, TV and radio broadcasting, the social media, popularized publications and exhibitions.
We expect that the project results will provide practitioners, managers and policy makers with the much-needed knowledge for better managing and preserving the unique biodiversity of mountain ecosystems.
- We used the power of eDNA metabarcoding to obtain high-resolution measures of biodiversity in these areas
Environmental DNA (eDNA) is the DNA that can be extracted from environmental samples without isolating the remains of organisms. Environmental samples contain the eDNA of multiple organisms, that can be amplified, compared with reference databases and identified in a procedure named eDNA metabarcoding. We extracted eDNA from >1200 soil samples, and amplified it using primes targeting multiple components of biodiversity: bacteria, fungi, protists, plants and animals.
- We performed bioinformatic analyses: from sequences to biodiversity information.
Several methodological analyses enhanced the rigour of our study. We compared approaches for soil preservation to identify the most robust protocol (Guerrieri et al. 2020) and contributed to methodological essays describing the best practices for biodiversity analyses using metabarcoding (Chen & Ficetola 2019; Zinger et al. 2019; Ficetola & Taberlet 2023). We generated a huge amount of genomic data that required extensive bioinformatics analyses.
- We produced high-resolution data on the environmental features of glacier forelands, particularly climate, soil and vegetation.
We produced the first reconstruction at very high resolution of temperature in proglacial environments at the global scale. These data showed that glacier forelands are warming much faster than other mountain areas (Marta et al. 2023).
We performed multiple analyses of soil features, to identify properties that affect the development of communities, and confirmed the importance of these parameters for soil fauna. We also showed that soil organic matter increases with time in glacier forelands, but the patterns of soil development are different across areas of the world (Fig. 4; Khedim et al 2021).
- We measured the biodiversity of communities.
eDNA data allowed measuring the development of biodiversity. We detected >10000 taxonomic units of bacteria, fungi, protists, plants and animals. The diversity of all groups of organisms increased through time after glacier retreat, but differences between taxa and areas of the world are strong.
- We show that communities evolve through two distinct mechanisms: species addition and replacement, and the importance of these mechanisms varied over time.
Taxa addition dominated immediately after glacier retreat, while replacement became more important for late-successional communities (Fig. 5).
- We show that biotic interactions, particularly mutualisms, are extremely important to favour colonization.
We found strong relationships between plants and fungi (e.g. mycorrhizal fungi), even at the early stage of colonization. This indicates that interactions have a major role for biotic colonization (Carteron et al 2024; Fig. 6). These associations depends from the balance between multiple biotic and abiotic factors.
- We show that climatic differences between areas of the world have strong impacts on the development of biodiversity.
Colonization is faster in forelands with mild summer temperatures, particularly at the early stages after glacier retreat. The effects of climate on biotic colonization led to heterogeneous but predictable patterns around the world that can affect likely determine the overall ecosystem development (Guerrieri et al 2024; Fig. 7)
Overall, the project greatly contributed to improve our understanding of the impact of climate change on biodiversity.
From the scientific point of view, it resulted in a large number of papers by project members (29 accepted papers, including papers in Nature Ecology & Evolution, Nature Plants, Nature Communications…)
The project results have been disseminated with a large number of strategies, including scientific conferences, TV and radio broadcasting, the social media, popularized publications and exhibitions.
We expect that the project results will provide practitioners, managers and policy makers with the much-needed knowledge for better managing and preserving the unique biodiversity of mountain ecosystems.
- We produced and analysed the broadest collection of samples from peri-glacial environments, covering all the continents
- We helped defining the best-practices for the analysis of environmental DNA
- We provide a first estimate of the amount of carbon sequestration as a consequence of glacier retreat, showing that SOM content increases faster in forelands experiencing warmer climates.
- - we show that that areas nearby glaciers suffer much faster warming than previously thought
- we produced the most complete, broadest assessment of biodiversity in peri-glacial environments, including extensive data also for tropical mountains
- we show that, during colonization, taxonomic and functional diversity follow parallel trajectories. Both taxonomic and functional diversity continue to increase for centuries after the retreat of glaciers, highlighting the long time required for the recovery of ecosystem functions
- we demonstrate that climate modulates the development of soil communities after glacier retreat
- we show that the same ecological processes affect the colonization of all the major groups of organisms: biotic interactions, habitat modifications and dispersal limitations
- We helped defining the best-practices for the analysis of environmental DNA
- We provide a first estimate of the amount of carbon sequestration as a consequence of glacier retreat, showing that SOM content increases faster in forelands experiencing warmer climates.
- - we show that that areas nearby glaciers suffer much faster warming than previously thought
- we produced the most complete, broadest assessment of biodiversity in peri-glacial environments, including extensive data also for tropical mountains
- we show that, during colonization, taxonomic and functional diversity follow parallel trajectories. Both taxonomic and functional diversity continue to increase for centuries after the retreat of glaciers, highlighting the long time required for the recovery of ecosystem functions
- we demonstrate that climate modulates the development of soil communities after glacier retreat
- we show that the same ecological processes affect the colonization of all the major groups of organisms: biotic interactions, habitat modifications and dispersal limitations