Abstract:
A comprehensive global analysis led by researchers at King's College London and Imperial College London has found that natural ecosystems may be far less buffering against species loss than previously thought. The study summarized 423 published studies, 222,829 data points, covering terrestrial, freshwater, marine and estuarine ecosystems, and analyzed 23 types of ecosystem services and functions. It is one of the largest studies of its kind to date.
Research results show that most ecosystem services will continue to increase as biodiversity increases and do not generally become saturated after the emergence of a few species. Regulatory services such as water purification and pollination often exhibit approximately linear relationships, meaning that the contributions of different species add up. The study thus suggests that "functional redundancy" - where different species can substitute for each other, so the loss of a few species has little impact - may be overestimated in many ecological services. When biodiversity declines, so do the ecological benefits that humans rely on, such as pollination, clean water, carbon storage, and natural pest control.
Among the services included in the study, ocean carbon sequestration has the strongest positive correlation with biodiversity. Marine phytoplankton and microbial food webs can promote the transfer of carbon from the sea to deep water and sediments, and coastal ecosystems such as mangroves and salt marshes are also involved in carbon storage. However, the research team reminds that this result comes from a relatively limited number of data sets. The current evidence is not enough to accurately estimate the impact of changes in marine biodiversity on blue carbon stocks. There are still obvious research gaps in related fields.
The study also found that not all services depend on species richness in the same way. Coastal flooding and erosion protection are generally less sensitive to biodiversity, possibly because these functions tend to be dominated by a few key foundation species, such as dune-anchoring shrubs. Therefore, conservation strategies must not only maintain overall species diversity, but also avoid the loss of certain key species that are difficult to replace.
The research team further combined the database with socioeconomic scenarios used by the United Nations Intergovernmental Panel on Climate Change to predict how natural pest control services on farmland may change along development pathways. Models show that a fossil fuel-driven development path would weaken this ecological service provided by natural enemies of pests compared with a scenario less dependent on fossil fuels; countries with faster population growth and lower levels of development are expected to face more pronounced losses. Researchers said that the complete database and prediction results covering 23 types of services and functions have been made public and can be used as a reference for policy formulation and planning.
The research was published in the journal Nature Ecology and Evolution. The authors emphasize that the results do not mean that each species plays a completely unique and irreplaceable role, but rather suggest that in most of the ecological services analyzed, the contribution of biodiversity tends not to disappear as quickly as a few species exist; the buffer space of ecosystems may be more limited than previously thought.
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