Soils are known to have enormous seed banks and there are some long-lived seeds which patiently wait to sprout until the seed dormancy period has passed. However, in an area where wetlands have been drained and cultivated for more than 10-15 years, seeds in the seed bank die and may not be able to propagate naturally (Wienhold and van der Valk, 1989). This has been the case in the Dheerpur Wetland Park (DWP) for a long period of time. It is possible that seeds that would otherwise propagate naturally in such areas might not be able to do so because of the history, present geography, topography and ecology of the local system.
In a barren land, seed dispersal might not be the best way of introducing grass species, whereas, vegetative transplantation might be a more effective method (Susan Galatowitsch in Ecological Restoration, 2012). The rhizomes of grasses which contain meristematic tissues that produce roots and shoots are sensitive to damage and must be transplanted with a lot of care. These meristematic tissues provide carbohydrates to the grass for a certain time period, giving the rhizome additional time to propagate. Within a few days, new roots and shoots develop and the photosynthesis process begins. With the old leaves dying, the new leaves provide carbohydrates to the grass structure. This phenomenon of growing roots and shoots from vegetative organs is known as adventitious growth. Grasses provide quick stability to the topsoil thereby controlling soil erosion. Grasses also maintain microbial activity in the soil and aid in the growth of successional species of vegetation.
Following the aforementioned protocol of vegetative transplantation, rhizomes of several grass species were carefully transplanted to a newly formed stretch of soil that was created as an extension to an already existing feature of the DWP.
The Centre for Urban Ecology and Sustainability (CUES) organized a plantation drive at the DWP on 19 August 2017 (1). Students from various graduate and undergraduate programmes of AUD Kashmere Gate campus, as well as faculty from the School of Human Ecology (SHE), participated in the event. Prior to the event, the plantation site needed to be prepared in order to create adequate space for plantation on the edges of the tarmac roads created by the Delhi Development Authority (DDA). The tarmac roads were very wide and therefore needed to be narrowed down to resemble the size of a jogging track.
Initially, some corners of the DWP area were full of construction debris. As part of the restoration process, this debris was levelled and covered by soil with the help of heavy-duty bulldozers. The soil that was used for this operation was lifted from adjacent areas to create an extended shoulder of nearly 10 feet over the debris, and the shoulder was then used for plantation activity. The thickness of the soil was maintained at 4-5 feet for grasses and plants to stabilize their roots before they penetrate the buried layer of construction debris.
We planted around 120 saplings on this extended stretch of soil as part of the plantation drive. Post-plantation of saplings, grass transplantation for vegetative regeneration took place on this same stretch. The grass rhizomes were uprooted from a nearby area for this exercise, and we made all possible attempts to protect these rhizomes. We expected that the introduction of grasses would give stability to the surface, and provide conducive conditions for the growth of the saplings.
As the week passed by, we observed the growth of the grasses. We saw how the newly transplanted grass leaves dry up and give way to new leaves. There is limited time available for the grass rhizomes to develop because invasive species may also soon compete with the grasses. The primary goal here was to establish a self-sustaining plant community in a small patch. After this grass transplantation exercise, it is expected that the small patch will sustain itself seasonally.
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(a) Drying of grasses in the regeneration process (b) Regeneration of grass (c) Roots re-settlement in the soil (d) Flourishing Grass rhizomes. Photos: Amit Kaushik
This process to ‘re-grass’ a stretch of 500m took around two months to complete and presently, the grasses are doing well (along with the saplings). I can only imagine how this area might look like in the coming years based on present vegetation communities and the wetland development plan. It is exciting to imagine that these restoration practices would someday form a part of the environmental history of our future jungles.