- Dark diversity refers to species absent from a study site but which are ecologically suitable to it and present in surrounding areas.
- A recent study notes that local plant diversity decreases as human activity in the surrounding region increases. Human damage can be revealed through dark diversity.
- The inclusion of Kashmir in this global study offers a starting point for replicating the findings for conservation of Indian biodiversity.
Dark diversity — species absent from a study site ecologically suitable to it and present in surrounding areas — gives a good estimate of global loss of biodiversity due to human activities, reports an international team of biodiversity experts, including from India.
In a global collaborative effort, DarkDivNet, over 200 scientists from 37 countries studied plants at nearly 5500 sites in 119 regions worldwide. Researchers for each local site documented all plant species, including native species that could have been present but were not. DarkDiv.Net started in 2018 and is led by the University of Tartu in Estonia.
The scientists attempted to understand negative human impacts of natural ecosystems through dark diversity. Their report published in Nature says that in the sampled regions with a minimal human footprint index, an average of 35% of suitable plant species were present locally, compared with less than 20% in highly affected regions.
They reported that as human activity in the surrounding region increases, the local plant diversity decreases. “Impoverishment of natural vegetation was evident only when we considered community completeness: the proportion of all suitable species in the region that are present at a site,” they say.
Besides having the potential to uncover overlooked threats to biodiversity, understanding dark diversity can also guide conservation. Species in the dark diversity remain regionally present, and their local populations might be restored through measures that improve connectivity between natural vegetation fragments and reduce threats to population persistence.
“So far, ecological studies have focused on analysing species that occur at a site. However, shifting the perspective and asking which species are missing and why, enables a deeper understanding of the processes that cause the current biodiversity loss,” says Kolja Bergholz from the Plant Ecology and Nature Conservation Group at the University of Potsdam, Germany, in a press release. Bergholz is a co-author of the study.
This study adds to other reports in 2025 on the use of dark diversity as an ecological metric. One such study is by scientists from the French National Centre for Scientific Research (CNRS), in Ecological Indicators, which notes that dark diversity and habitat conservation status metrics complement conservation and restoration. A second study published in the book Forest Science says that while the practical application of dark diversity is still emerging, advances in ecological modelling and local knowledge integration are making dark diversity a valuable tool for guiding biodiversity conservation and forest ecosystem restoration.
India implications
Anzar Khuroo, one of the authors of the Nature report and professor of botany at the University of Kashmir, Srinagar, told Mongabay India that the study revealed that even seemingly intact natural areas in India may suffer hidden biodiversity loss, as many ecologically suitable species are absent locally despite being present regionally.
This suggests that widespread human activities such as infrastructure development, including road construction, tunnels, hydroelectric projects, livestock overgrazing, mining, unregulated tourism and pollution, are reducing biodiversity far beyond the visibly disturbed areas, says Khuroo.
For India, where landscapes are densely populated and highly modified, this underscores the need for regional-scale conservation strategies that go beyond protecting isolated patches, he says. “Importantly, the persistence of many missing species in surrounding areas offers a critical but time-sensitive opportunity for ecological restoration.”
To effectively monitor and guide conservation, India should adopt more comprehensive biodiversity metrics like dark diversity and community completeness, which reflect both observed and potential species diversity, suggests Khuroo.
“A potential value of this (the study) approach is that we can generate estimates of diversity across large spatial scales even by sampling smaller areas,” says Meghna Krishnadas, scientist at the National Centre for Biological Sciences, Bengaluru. Sampling extent is often a key limitation of biodiversity assessments as the effort increases substantially as we try to scale up and it is often infeasible to cover depth and breadth, she says. “The dark diversity approach may help to approximate the regional biodiversity better,” says Krishnadas.
This framework can be effectively applied for India, as the Kashmir region was sampled in this study and serves as a representative area, says Khuroo. Kashmir’s ecological richness and history of human influence — including land-use change, grazing, deforestation and tourism — provides a meaningful context to assess dark diversity and community completeness.
In India, scientists should move beyond basic species counts and adopt advanced biodiversity metrics like community completeness to reveal hidden biodiversity loss, says Khuroo.
He adds that restoration efforts must focus on landscape-scale connectivity, especially in fragmented ecosystems. The presence of regionally suitable but locally absent species (dark diversity) offers a unique opportunity for ecological restoration. Traditional, low-intensity land-use practices should be supported as biodiversity-friendly strategies.
The inclusion of Kashmir in this global study offers a starting point for replicating the findings for conservation of Indian biodiversity, says Khuroo. “By analysing the observed versus expected diversity in this Himalayan region, we can gain valuable insights into the extent of hidden biodiversity loss in India and use these scientific insights to inform conservation and restoration strategies at biogeographical scale in the country.”
Kashmir region, already included in the study, can serve as a model for applying this framework across other Indian landscapes, he asserts. These insights should inform conservation strategies, restoration efforts, and biodiversity policy and action plans at regional and national scales, he says.
However, more studies are perhaps needed before global findings can be extrapolated for making India estimates. “At these large scales, there are many variables due to which diversity patterns can differ even across seemingly similar regions,” says Krishnadas. However, it might be worth using existing inventory data to check the value of this method for Indian ecosystems or regions, she adds.
“We need coordinated efforts to collect, compile, and synthesize biodiversity data across large spatial scales,” says Krishnadas. This data should be available collaboratively and form part of an accessible database, preferably with regular updates, which can be used for analyses.
Read more: Alpine plants may alter height or leaf size to cope with early snow-melt conditions
Banner image: A carabid beetle. One study by scientists that are part of the DarkDivNet network assessed plants, fungi and carabid beetles in Estonia and found that dark diversity was greater than observed diversity within all groups. Representative image by Bernard Dupont via Wikimedia Commons (CC BY-SA 2.0).
Credits
