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Contrary to expectations, some human-modified landscapes are considered to sustain both human activities and biodiversity over the long-term. Agroforestry systems are among these landscapes where crops are planted under native shade trees. In this context, ancient agroforestry systems can provide insight into how farmers managed the landscape over time. Such insight can help to quantify the extent to which tropical forests (especially habitat-specialist trees) are responding to local and landscape-level management. Here, we extracted fossil pollen (indicator of past vegetation changes) and macroscopic charcoal (indicator of biomass burning) from four forest hollows’ sedimentary sequences in an ancient agroforestry system in Western Ghats, India. We used a mixed-modelling approach and a principal components analysis (PCA) to determine past trajectories of forest change and species composition dynamics for the last 900 years. In addition, we reconstructed the long-term forest canopy dynamics and examined the persistence of habitat-specialist trees over time. Our results show that the four sites diverged to a surprising degree in both taxa composition and dynamics. However, despite these differences, forest has persisted over 900 years under agricultural activities within agroforestry systems. This long-term analysis highlights the importance of different land-use legacies as a framework to increase the effectiveness of management across tropical agricultural lands. [ABSTRACT FROM AUTHOR]

Sacred forest groves in the Western Ghats of India are small fragments of tropical forest that have received protection due to religious beliefs and cultural practices. These forest fragments are an example of community-based conservation and they serve as refugia for many forest-dwelling species in otherwise highly anthropogenic tropical forest-agriculture landscapes of the Indian Western Ghats. Many of these sacred forest groves are considered ancient woodlands, but there is very little information on their origins. For instance: How old are these sacred groves? Are they relics of forest that was once continuous or are they patches of regenerated vegetation? How do changes in the surrounding landscape influence the vegetation in these groves? Based on palaeoecological reconstruction in two such sacred forest groves, we determined the age of these forest fragments. Both reconstructions indicate transition from non-forest open landscape to tree-covered landscape at these sites. These finding from two sacred groves challenge the common perception that sacred forest groves are remnants of once-continuous forest; instead, some sacred groves such as those studied might be regenerated forest patches that are approximately 400 years old. This further raises a number of questions about the drivers of reforestation in these groves. What were the social and cultural circumstances which led to the recovery of forest within these patches? How did land tenure influence forest recovery? What role did religious beliefs play in forest restoration? Using Wallace's (1956) framework of 'cultural revitalization' and based on historical literature and palaeoecological analysis of the two sacred groves, this paper examines the drivers of reforestation in the Western Ghats of India. It suggests various social, ecological and economic drivers of such revitalization, recognizing strong linkages between the 'social' and the 'ecological' within the social-ecological system of sacred forest groves. This example of reforestation suggests that contemporary restoration of forests needs to operate at a landscape scale and look at restoration as a social-ecological intervention in forest management. [ABSTRACT FROM AUTHOR]

Identifying the impacts of anthropogenic fires on biodiversity is imperative for human-influenced tropical rainforests because: i) these ecosystems have been transformed by human-induced fires for millennia; and ii) their effective management is essential for protecting the world's terrestrial biodiversity in the face of global environmental change. While several short-term studies elucidate the impacts of fires on local plant diversity, how plant diversity responds to fire regimes over long timescales (>100 years) is a significant knowledge gap, posing substantial impediment to evidence-based management of tropical social-ecological systems. Using wet evergreen forests of the Western Ghats of India as a model system, we discuss the synergistic effects of anthropogenic fires and enhanced aridity on tropical plant diversity over the past 4000 years by examining fossil pollen-based diversity indices (e.g., pollen richness and evenness, and temporal β-diversity), past fire management, the intervals of enhanced aridity due to reduced monsoon rainfall and land use history. By developing a historical perspective, our aim is to provide region-specific management information for biodiversity conservation in the Western Ghats. We observe that the agroforestry landscape switches between periods of no fires (4000-1800 yr BP, and 1400-400 yr BP) and fires (1800-1400 yr BP, and 400-0 yr BP), with both fire periods concomitant with intervals of enhanced aridity. We find synergistic impacts of anthropogenic fires and aridity on plant diversity uneven across time, pointing towards varied land management strategies implemented by the contemporary societies. For example, during 1800–1400 yr BP, diversity reduced in conjunction with a significant decrease in the canopy cover related to sustained use of fires, possibly linked to large-scale intensification of agriculture. On the contrary, the substantially reduced fires during 400–0 yr BP may be associated with the emergence of sacred forest groves, a cultural practice supporting the maintenance of plant diversity. Overall, notwithstanding apparent changes in fires, aridity, and land use over the past 4000 years, present-day plant diversity in the Western Ghats agroforestry landscape falls within the range of historical variability. Importantly, we find a strong correlation between plant diversity and canopy cover, emphasising the crucial role of maintenance of trees in the landscape for biodiversity conservation. Systematic tree management in tropical social-ecological systems is vital for livelihoods of billions of people, who depend on forested landscapes. In this context, we argue that agroforestry landscapes can deliver win-win solutions for biodiversity as well as people in the Western Ghats and wet tropics at large. • Effective fire and ecological management in tropics require a long-term perspective. • In the Western Ghats, fires-plant diversity relationship is non-linear across time. • Fire management in the Western Ghats demands an inclusive and integrative approach. • Tree cover is the vital determinant of sustaining plant diversity in wet tropics. • Agroforestry is a win-win solution for tropical biodiversity and peoples' livelihoods. [ABSTRACT FROM AUTHOR]