Indian grasslands hold a treasure trove of endemic plants

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  • Indian savannahs contain 206 endemic plant species, 43% of which have been described in the last two decades. Other endemic species are waiting to be discovered, a new study points out.
  • The grasslands of Eastern Ghats and Western Ghats are hotspots for finding endemic plant species.
  • According to experts, grasslands are just as important as forests in biodiversity conservation and climate change mitigation goals.

Indian savannahs, often referred to as “degraded forests” in the context of reforestation, are likely to produce “tons of new plant species”, Indian scientists say in a new study.

By sifting through taxonomic records from the 1780s to September 2020, scientists found that the Indian peninsula’s savannahs, or grassland ecosystems, contain 206 endemic plant species, 43% of which have been described in the last two decades (after 2000 ). Before the rapid increase in discoveries after 2000, the 1830s, 1880s, and 1980s show three smaller discovery peaks.

“There were 68 species described in the decade 2010-2020 alone, and if you look at our data, the trend is for an exponential increase in discoveries, which means that several more species remain unknown to science, scientists and biologists. conservation,” said study corresponding author Ashish N. Nerlekar, Department of Ecology and Conservation Biology, Texas A&M University, College Station, Texas, USA.

The authors, while expecting an increase, were surprised by the exponential increase in species discovery over the years. They highlighted the need to invest in training more botanists, prioritizing hotspots for biodiversity surveys and managing savannas to support endemic species diversity.

The records analyzed in the study ranged from the grasslands of Rajkot in Gujarat to Pune and Nannaj in Maharashtra and Mahakuta in Karnataka to the Eastern Ghats and Pench Tiger Reserve, Madhya Pradesh. Some of the most important endemic species that grasslands support are Crotalaria shrirangiana (Fabaceae), Tephrosia calophylla (Fabaceae) Brachystelma penchalakonense (Apocynaceae) and Brachystelma gondwanense (Apocynaceae).

“The objectives of the Convention on Biological Diversity will only be achieved if we accelerate the discovery of missing species before they become extinct. Since the number of endemic species present in a given region is a basic measure for deciding conservation interventions and priorities, our study helps provide the first estimate of these large-scale savannas,” Nerlekar added.

According to the analysis, the eastern edge of the Western Ghats and Eastern Ghats mountains are the two hotspots for plant finds, and future finds are most likely to be small and rare plants, which matches finds in d ‘other countries. groups like butterflies.

Nerlekar added, “Biologists tend to encounter larger, more common species first than smaller/inconspicuous and rare species. This is actually a very intuitive reason for the patterns of plant and animal discoveries in many parts of the world. Once the more common and more apparent species are described, it is much more difficult to search for smaller and rarer species.

Indian Peninsular Indian savannas or grassland ecosystems contain 206 endemic plant species, 43% of which have been described in the last two decades (post 2000). Study graph.

It’s no surprise that the mountains contain hotspots for encountering new species. Mountains support a diversity of climates, microclimates and habitats and the microhabitats in these mountains provide an ideal opportunity for speciation and the maintenance of endemic diversity. The evolution of endemic species in the Indian grasslands also reflects the region’s paleohistory, researchers said.

India, after splitting off from the Gondwana supercontinent, went through various paleoclimatic belts crossing the equatorial climate, experiencing the evolution of various plant communities, including the ancestral plant forms of the current plant communities.

An example is Glossopteris, extinct seed ferns that are primitive plant forms of present-day seed plants, observed study co-author R. Ganeshan. “As part of the evolution along the climatic belts through which, as the Indian plate advanced, various plant communities continued to alter their range and population size. During the movement of tectonic plates, many plants disappeared; and also the same process that is driven for extinction also facilitated the origin of new taxa,” Ganeshan told Ashoka Trust for Research in Ecology and the Environment (ATREE), Mongabay-India.

Rainforest habitats transformed into salt marshes or deserts and ice-covered mountains were later enveloped by rainforests. Some plants escaped these changes by taking refuge in the mountains or valleys and spreading and evolving when the favorable climate prevailed. Aridity and the Ice Age shaped life on earth and the evidence is recorded in the form of coal deposits or fossil forms, not only in the Indian subcontinent but also around the world, Ganeshan said.

The evolution of endemic plants in the arid savannah biome can be traced in the plant biodiversity of peninsular India, along with the Eastern and Western Ghats and the Deccan Plateau. “These savannah biomes of India are also home to the evolution of various crop plants following human footprints,” he said.

Botanist Anzar Khuroo, who was not associated with the research, says the study has implications for biodiversity conservation and for policies and programs associated with climate mitigation which tend to focus primarily on trees. “Don’t just take forests as green countryside or for biodiversity conservation. It is the mosaic of ecosystems that is important. There are many types of open landscapes that are equally important for biodiversity and this study has helped a lot to bring this point home.

“These grasslands, often referred to as ‘wastelands’, are just as important as forests when we talk about climate change mitigation, biodiversity conservation and sustainable development,” Khuroo told Mongabay-India. “Tomorrow, if we have development projects in these open-type landscapes, there will be no public outcry because they do not occupy the same space in the public consciousness as forests do,” he warned. . Khuroo expects similar results in the Himalayan grasslands.

Open landscapes of the Indian savannahs of Rajasthan.  Photo by Sahana Ghosh.
Open landscapes of the Indian savannahs of Rajasthan. Photo by Sahana Ghosh/Mongabay.

The authors of the study are fighting to make savannahs a conservation priority like forests.

“Most existing conservation prioritization activities and analyzes have used endemism as a proxy indicator to identify high priority areas for conservation. Since savannas have always been assumed to be endemic-free landscapes, they have always been an ignored conservation priority as opposed to forests. Our data now shows that there is considerable endemism in these savannas as well and conservation priorities now need to be realigned to protect both forests and savannas,” said Ashish Nerlekar .

Training more and better botanists would increase the “arduous task” for botanists to find missing species, as future plant discoveries are expected to be of small-bodied, restricted-range plants.

“With limited resources allocated to field biology and taxonomy, if one were to prioritize areas given these funding constraints, focusing on the two hotspots (Eastern Ghats and Western Ghats) might be a desirable option,” Nerlekar said.

The authors also called for managing savannas in a way that maintains endemic diversity.

“Several of the endemic plants we list exhibit traits known to be adaptations to fire and grazing (e.g., presence of underground bud banks, fire-stimulated germination, etc.). These adaptations, along with other evidence (e.g. fossil pollen data) clearly shows that fire and grazing have historically been an important driver in maintaining and shaping endemic plant diversity Unfortunately, fire and grazing are seen as driving forces degrading even by botanists, with little empirical evidence to support these claims, and in this context we recommend that Indian savannas be managed in a way that best mimics historical grazing and fire regimes,” says Nerlekar.

“Managing savannas as savannas is also an important implication of our study rather than undertaking misplaced reforestation campaigns that view them as ‘degraded forests’ and aim to ‘restore’ these naturally open-canopy landscapes to the state of the forest,” he added.

QUOTE:

Nerlekar, AN, Chorghe, AR, Dalavi, JV, Kusom, RK, Karuppusamy, S., Kamath, V., Pokar, R., Ganesan. R., Sardesai, MM & Kambale, SS (2022). The exponential increase in the discovery of endemic plants highlights the need to conserve Indian savannas. Biotropica.

Banner image: Tephrosia calophylla is an endemic species found in Indian grasslands. Other endemic species are waiting to be discovered, a new study points out. Photo by R. Ganesan.

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