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Picture Courtesy: https://www.thehindu.com/sci-tech/energy-and-environment/india-open-ecosystems-unusual-threat-woody-encroachment/article68463152.ece
Context: India's open ecosystems, such as grasslands and savannahs, are threatened by woody encroachment, where increased tree cover disrupts their natural disturbance regimes and harms native biodiversity.
Details
- Open ecosystems such as grasslands and savannahs, historically crucial for biodiversity, face an unusual threat: the encroachment of trees. This phenomenon, known as woody encroachment, has significant ecological implications, particularly in regions like India where diverse grassland habitats are being transformed into woody landscapes. The trend, driven by human activities and climate change, poses severe risks to native species and the ecological balance.
The Impact of Woody Encroachment
- Woody encroachment refers to the process where open habitats are converted into areas with increased tree cover and shrub density. This shift results in the homogenization of ecosystems, turning diverse, multi-layered habitats into uniform woody plant layers.
Threat to Biodiversity
- Grassland Birds: In the African savannah, for example, an increase in tree cover has led to a decline of more than 20% in grassland bird populations. Birds like bustards, floricans, and grouse, which depend on open grasslands, are particularly affected.
- Grassland Specialists: Species adapted to grasslands, including rodents and other fauna, suffer from increased predation and reduced feeding opportunities as woody plants alter the landscape.
Drivers of Woody Encroachment
Several factors contribute to woody encroachment in open ecosystems:
- Climate Change: Increased atmospheric CO2 promotes the growth of deep-rooted woody plants over grasses.
- Fire Suppression: Natural fires, which help maintain grasslands by limiting tree growth, are often suppressed, allowing trees to establish and proliferate.
- Grazing: Reduced grazing by herbivores, which naturally maintain open habitats, contributes to tree encroachment.
- Colonial Practices: Historical policies regarded grasslands as "wastelands," leading to their conversion for plantations and agriculture. Modern conservation efforts often overlook the importance of these habitats, further promoting woody encroachment.
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Case Studies
●African Savannah: Studies have shown a decline in grassland birds correlated with increased tree cover.
●Indian Grasslands: Research using satellite data revealed significant woody encroachment in India's national parks, where grassland habitats shrank by 34% over three decades, while tree cover increased by 8.7%.
●Banni Grasslands: The introduction of the invasive species Prosopis juliflora has transformed large areas of these grasslands into woodlands.
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Ecological Consequences
Woody encroachment changes soil conditions, plant composition, and the faunal associations of ecosystems. For instance, increased tree cover in grasslands results in:
- Altered Soil and Vegetation: Shaded areas and suppressed fires change the native grass species and soil conditions.
- Increased Predation: Trees offer perches for predators, increasing the risk for ground-nesting birds and small mammals.
- Survival Penalties: Grassland specialists spend more time avoiding predators and less time feeding, impacting their survival.
Conservation Implications
Protecting open ecosystems requires recognizing the value of grasslands and savannahs, not just for biodiversity but also for their ecological functions. Efforts to combat woody encroachment include:
- Restoring Disturbance Regimes: Reintroducing controlled grazing and fire management to maintain grasslands.
- Policy Changes: Dismantling colonial terminologies like "wastelands" that misclassify grasslands and promote their conversion.
- Long-term Monitoring: Conducting extensive ecological studies to understand and mitigate the impacts of woody encroachment.
Conclusion
- Woody encroachment poses a significant threat to India's open ecosystems, driven by a combination of climate change, historical land-use policies, and suppression of natural disturbance regimes. Addressing this issue requires a comprehensive understanding of the ecological dynamics at play and implementing conservation strategies that prioritize the preservation of grasslands and savannahs.
Source:
THE HINDU
WIKIPEDIA
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PRACTICE QUESTION
Q. Woody encroachment frequently seen in the news is described as:
A) The expansion of grasslands into forested areas.
B) The increase in tree and shrub cover in open habitats like grasslands and savannahs.
C) The deforestation of tropical rainforests.
D) The conversion of wetlands into dry land.
Answer: B |
