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The ability to constantly adapt to changing environments is the primary reason that single-celled and multicellular organisms have been able to survive on this planet for years. Despite continuous changes that take place within an ecosystem, it continues to thrive and adapt independently as long as the changes depend on environmental factors. But once human intervention occurs, independent survival becomes nearly impossible. The extinction of species is estimated to have increased between 1000 and 10,000 times the normal rate after human intervention.
While the obvious reason for habitat loss is rapid urbanisation and rising demands, the reasons for changing landscapes aren’t so obvious. There is a common misconception that everything green around us is always healthy. In the process of turning the lands ‘green’, self-sustaining habitats are transformed into completely unrecognisable sites. Considering marshlands and grasslands as wastelands and planting tall trees to increase green cover have disturbed the existing biodiversity of the area, ruining completely healthy ecosystems.
Most of the times during tree plantation drives, hardy plants are planted on the site. It is a common trend that these plants happen to be invasive, which is why they can adapt and grow even in adverse conditions. But in the process of thriving, these plants outnumber the native floral diversity, taking a heavy toll on the existing fauna as well. Thus the ecosystem is dramatically upturned, also adversely affecting the ecosystem services that we humans often derive. Identifying plants that historically existed in such lands and replanting them has become one of the vital steps to save these lands. The process involving such activities that attempt restoring degraded ecosystems is known as ecological restoration, and the study which goes behind practising this method is called restoration ecology.
Before starting an ecological restoration project, clear objectives need to be set and a reference site with a healthy ecosystem, having similar environmental conditions is always helpful. The main aim of the project in most cases is to bring back the degraded habitat to its original condition. But in scenarios where full restoration is not possible, ecologists attempt to restore habitats up to a point where they can withstand stresses even without human intervention. At times the entire land is cleared and left for vegetation to re-establish with zero human interference and the term for it is ‘secondary succession’. Whatever the method, it is necessary to pinpoint the exact cause of site degradation rather than just treating the symptoms to ensure that the earlier problems do not persist and a conservative approach of repairing the damaged is taken as against complete replacement.
Let us take the example of Pune city. Pune, since historical times, has never fallen into the category of the area under dense evergreen vegetation. But due to lack of awareness in the year 1990, Gliricidia sepium, which is a fast-growing hardy tree was planted all over the so-called barren slopes of hillocks (tekdi) to increase green cover and to protect the land from land grabbers. Over the years the species outnumbered the native plant populations, thus heavily damaging the existing ecosystems and creating novel ecosystems all over the city. Today, nearly 50 hectares of land is being cleared of the species. Gliricidia sepium has a property of allelopathy, i.e. it secretes certain chemicals which do not allow any vegetation to grow around it and also turns the soil acidic. Apart from the negatives, the leguminous tree helps to fix nitrogen in the soil. Thus, now suddenly removing the tree species could, in fact, worsen the situation. This is why the forest department has taken up an ecological restoration project, where after a detailed study, nitrogen-fixing native trees which can survive in acidic soil and dry conditions will be planted. Historical records are being used while planning the project. The department hopes to retrieve at least some of the lost biodiversity of Pune through the process of ecorestoration.
Nature has always optimized its resources and humans have never left a chance to exploit them. In the greed for more, we have not only over-utilised the resources but have also unnecessarily interfered in nature’s cycle of self-healing. Although today, with in-depth studies, attempts are being made to reverse the damage, there is only little that ecologists can do. But let us together preserve the existing intact habitats by planting trees only after consulting experts instead of converting them into novel ecosystems.
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