Bryophytes, an ancient group of plants including mosses, liverworts, and hornworts, were among the first plants to colonize land, doing so nearly 470 million years ago. With over 20,000 known species, they are the second largest group of land plants after flowering plants. However, despite their evolutionary importance and vital ecological roles, bryophytes remain largely overlooked in global conservation policy.

In a study published in Global Change Biology on March 9, researchers from the Xishuangbanna Tropical Botanical Garden (XTBG) of the Chinese Academy of Sciences have provided the first comprehensive global assessment of bryophyte diversity, extinction risk, and conservation gaps. They synthesized global occurrence data, elevational records, IUCN Red List assessments, and published case studies to examine the increasing threats to this functionally critical plant group posed by human activities.

The researchers identified 37 countries and regions, each of which is home to more than 1,000 bryophyte species. However, only 1.5% of all described bryophytes have been evaluated using the IUCN Red List criteria. Of those evaluated, over half are threatened with extinction, nearly double the global average for all plant species.

The researchers emphasized the indispensable role of bryophytes in ecosystems. Species and phylogenetic diversity peak at elevations between 1,000 and 2,000 meters, which underscores the importance of tropical and subtropical mountain ecosystems. Agriculture and deforestation were identified as the primary global threats to bryophyte diversity.

Currently, bryophyte conservation research and funding are concentrated in regions such as Europe. However, the true hotspots of bryophyte diversity, particularly in tropical mountains, remain severely understudied and underfunded.

The researchers urged immediate action to protect thousands of bryophyte species. They called for a massive global effort to assess extinction risks and develop region-specific conservation strategies.

They recommend tailoring conservation plans to regional threats by mitigating climate warming in Europe, protecting forests in the tropics, and managing invasive species in Asia and Oceania.

They also advocated redirecting research funding and capacity-building efforts to tropical biodiversity centers, which have the highest diversity of bryophytes.

"Bryophytes are foundational to carbon storage, water regulation, and nutrient cycling across terrestrial ecosystems. If global biodiversity strategies continue to neglect bryophytes, we cannot truly achieve our goals of reducing species extinction rates and maintaining ecosystem functions," said YIN Xiangbo of XTBG.

Bryophytes in subtropical forest. (Image by XTBG)