Sacred Groves Emerge as Silent Giants in India’s Biodiversity Hotspot

Deep in the mountainous spine of western India, an unexpected conservation hero is standing quietly among the trees. A new study of the Northern Western Ghats—one of the most biologically rich and heavily fragmented landscapes on Earth—has revealed that sacred groves, forests protected not by law but by centuries of religious tradition, harbor the largest and oldest trees in the region, even though they experience the highest levels of human disturbance. The findings, published in the journal Discover Ecology, challenge the assumption that formal protected areas are the sole guardians of tropical forest biodiversity and suggest that the future of conservation in this hotspot may depend on a mosaic of very different management systems working in concert.

The research, led by Bhushan K. Shigwan and colleagues at the Agharkar Research Institute in Pune, set out to answer a deceptively simple question: do different kinds of forest protection actually produce different kinds of forests? The team compared four distinct protection regimes across the Northern Western Ghats and the adjacent Konkan coastal belt—state-run Protected Areas such as national parks and wildlife sanctuaries, government-managed Reserved Forests, community-protected Sacred Groves, and privately owned forests that include coffee plantations and silvicultural holdings. While earlier studies had examined individual regimes in isolation, no comprehensive survey had systematically compared tree diversity, community structure, and species composition across all four within this region as an integrated landscape.

The scale of the effort was considerable. Between 2017 and 2021, the researchers laid out forty transects—ten in each protection regime—stretching across an elevational range from 26 to 1,411 meters above sea level and a latitudinal span of nearly five degrees. Each transect ran 140 meters and contained four quadrats of 20 by 20 meters, spaced with 20-meter gaps to reduce spatial autocorrelation. Within every quadrat, the team measured all woody individuals with a girth at breast height of at least 30 centimeters, recording species identity, abundance, and trunk dimensions. Field identifications were verified against herbarium specimens at the Agharkar Herbarium of Maharashtra Association, and sampling was deliberately timed between December and May to avoid the monsoon, minimize phenological bias, and comply with access restrictions during wildlife breeding periods.

To quantify human pressure, the researchers scored eight categories of disturbance at each site—cutting, lopping, fire, grazing, construction, internal pathways, other human activities such as festivals and tourism, and proximity to roads—on an ordinal scale from zero to five. These scores were aggregated into a Combined Disturbance Index, a single number capturing the overall anthropogenic footprint of each forest. The results were striking. Sacred Groves recorded the highest average disturbance score at 47.75, followed by private forests at 34.5 and Reserved Forests at 31.5, while Protected Areas enjoyed the lowest at 17.5. The differences were statistically significant, confirming that the four regimes genuinely represent a gradient of human impact rather than merely different labels on similar land.

In total, the team recorded 3,360 woody plants representing 148 species, 118 genera, and 43 families. Reserved Forests emerged as the diversity champions, with the highest number of species at 89, along with the greatest richness of evergreen and endemic species. Protected Areas followed closely, while Sacred Groves matched Protected Areas in species count. Private forests told a different story: they hosted the highest richness and abundance of deciduous species and the lowest representation of evergreens, painting a picture of communities shifted toward disturbance-tolerant, drought-deciduous taxa. Shannon diversity values ranged from 1.13 to 2.98 across sites, and permutation-based analysis of variance revealed significant differences in species richness among regimes, though post-hoc tests suggested these arose from modest but consistent shifts rather than any single dramatic contrast.

Perhaps the most technically revealing results came from the structural analysis. Tree density differed strongly among regimes, with Reserved Forests and Protected Areas supporting the highest stem counts, dominated by individuals in the smallest girth class of 30 to 60 centimeters—a signature of active regeneration and younger, recovering stands. Sacred Groves, by contrast, showed lower densities but the highest mean basal area at 42.33 square meters per hectare, significantly exceeding both private forests and Reserved Forests. In the largest girth classes, above 150 centimeters, Sacred Groves held significantly more trees than any other regime. These giants, some potentially centuries old, represent legacy biomass that younger forests cannot replicate, and they position sacred groves as critical reservoirs of carbon and structural complexity in a fragmented landscape.

Community composition told a subtler story. Non-metric multidimensional scaling of site-level abundances showed that most sampling sites from Protected Areas, Sacred Groves, and Reserved Forests clustered tightly together, indicating broad overlap in species assemblages. Cluster analysis identified two main groupings—Sacred Groves with Protected Areas, and private forests with Reserved Forests—with overall similarity between regimes hovering around 38 percent, and roughly 50 to 54 percent within the paired groups. Only 26 species were shared across all four regimes, while each harbored 11 to 20 unique species. An analysis of similarities confirmed that compositional differences among regimes were weak and statistically non-significant, suggesting that chronic disturbance reshapes forest structure and functional traits without necessarily causing wholesale turnover in which species are present.

One species stood out as the great connector of these fragmented worlds. Memecylon umbellatum, a shade-intolerant, early-successional tree dispersed by birds and mammals, ranked among the dominant species in every protection regime, contributing disproportionately to total abundance everywhere the team looked. Its ubiquity likely reflects both its tolerance of canopy disturbance and the persistence of animal dispersal vectors across the landscape. Seed dispersal analysis added another layer: autochorous, self-dispersing species were significantly more common in private and Reserved Forests, where disturbed microhabitats favor them, while zoochorous, animal-dispersed species—typical of evergreen forests—remained well represented across all regimes, hinting that ecological relationships between trees and their dispersers persist even in degraded stands.

The conservation implications are profound. The authors argue that no single protection regime can represent the full biodiversity and structural value of the Northern Western Ghats; instead, the region’s ecological integrity rests on the complementarity of its management mosaic. Sacred Groves, sustained for generations by socio-cultural norms rather than enforcement, act as refugia for mature trees and endemic species, yet they are increasingly threatened by urbanization and the erosion of traditional practices, with significant losses reported over the past five decades. Protected Areas and Reserved Forests, meanwhile, are the engines of regeneration, teeming with young stems that promise future canopy. Private forests, though the most degraded, offer the greatest restoration opportunity: reintroducing evergreen and endemic species at lower elevations could recover biomass, carbon storage, and habitat connectivity.

For a biodiversity hotspot where primary forest loss and human pressure continue to mount, the message is clear and urgent. Formal legal protection matters—it suppresses disturbance and nurtures the next generation of forest. But cultural protection matters too, in ways that law cannot replicate, preserving the ancient giants that anchor forest ecosystems. The researchers call for regime-specific conservation strategies that pair disturbance regulation and restoration in private and community forests with renewed support for the community stewardship that keeps sacred groves standing. In the Northern Western Ghats, saving biodiversity will require not one fortress of conservation, but an entire alliance of them—legal, cultural, and private—each playing an irreplaceable role in sustaining the forest of the future.

Subject of Research: Comparative assessment of tree diversity and forest structure across four protection regimes in the Northern Western Ghats, India

Article Title: Assessing the impact of differential protection regimes on tree diversity and composition in the Western Ghats: insights for conservation strategies

Article References: Shigwan, B. K., Kulkarni, A., Smirthy, V., Page, N. V., Shetti, R., & Datar, M. N. (2026). Assessing the impact of differential protection regimes on tree diversity and composition in the Western Ghats: insights for conservation strategies. Discover Ecology, 2(1), Article 2. https://doi.org/10.1007/s44396-025-00016-7

Image Credits: AI Generated

DOI: 10.1007/s44396-025-00016-7

Keywords: Western Ghats, sacred groves, tree diversity, forest conservation, protected areas, basal area, endemic species, anthropogenic disturbance, seed dispersal, biodiversity hotspot, community conservation, forest structure