Natural regeneration in restoration is an understudied field.  Sharing real life cases that have trialed the potential and limits of natural regeneration is one of the best ways to fill knowledge gaps and help us anticipate what is possible and what techniques are helpful.  This will lead to more reliable planning to improve restoration success.  

Our network is international and so are keen to link members to a wide range of examples from around the world – including sites that represent a range of degradation levels.  These may be published on this website, on SER’s restoration resources database and or in SER’s newsletters

Do you have a natural regeneration project that you would like to share through this website? If so, please use this link to submit your project, or email SERNRN@gmail.com for more information.

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ORIGINAL (SER-NRN) CASE STUDIES   (See also our ‘Links to a range of Case Studies‘)

Featured Case Study 1 – Use of Assisted Natural Regeneration techniques to restore dry deciduous forest ecosystems in South India

Ramesh Venkataraman

Introduction

Junglescapes has been restoring degraded forests in the core and buffer areas of the Bandipur Tiger Reserve in South India since 2008, using natural regeneration techniques (after a period of unsuccessful reintroductions). The restoration sites fall within the tropical forest biome and consist of tropical dry deciduous and thorn forest ecosystems. The restoration sites are part of the Western Ghats of India, a global biodiversity hotspot.

Fig 1. Typical example of regions of degraded regions prior to restoration (2008)

The project sites in the buffer areas of the tiger reserve are located within the Lokkere Reserve Forest, an important elephant corridor. These have faced persistent degradation due to high anthropogenic pressures like cattle grazing, firewood collection, etc as well as presence of invasive species like lantana (Lantana camara).  Prior to commencement of restoration, these cumulative impacts meant that these sites had very poor vegetation species / structural diversity and abundance (less than 20% compared with  identified reference sites) as well as high soil compaction. This resulted in high rainwater run-off, soil erosion, poor soil health and low vegetation and animal presence. Poor habitat health also led to increased ingress of wild animals, particularly elephants and wild boar, into farmlands at the periphery of the forest, leading to high crop losses. The project sites in the core area of the tiger reserve have been facing high degradation due to the presence of multiple invasive alien species including lantana, senna (Senna spectabilis) and Siam weed (Chromolaena odorata), resulting in significant reduction in recruitment of native plant species, severe loss of native biodiversity, and impaired wildlife habitats with low biomass and fodder availability. The high presence of Lantana also led to frequent forest fires. The high presence of invasive species also led to disappearance of many micro-habitats, with far reaching impacts on a wide array of faunal species.

Fig. 2 a&b. Examples of landscape infested with lantana and its removal by Cut Root Stock Method

Bandipur Tiger Reserve is a protected area governed by the Government. The lands therefore belong to the State. A number of village communities live at the edges of the reserve. They benefit from the reserve through improved water tables, rich silt from streams flowing out of the forest and utilised for farming, better micro-climatic conditions, etc.

Key restoration goals for the project site were the revival of biodiversity closer to the reference model, restoration of healthy wildlife habitats that facilitate return of fauna, reduction in human-wildlife conflict, and community benefits in the form of conserving traditional knowledge and creating restoration-based livelihoods.

Works undertaken

Restoration works undertaken at the site include:

  1. Removal of invasive species, mainly lantana
  2. Measures to harvest rainwater to improve soil moisture levels. These consisted of a variety of methods such as the construction of short trenches of 4 feet in length, longer contour trenches in multiples of 10 feet length each, swales, rock detention structures that help slow down water flow, etc.
  3. Creation of small water bodies to augment water availability for fauna, so that the return of fauna can facilitate seed dispersal in the plots
  4. Reversal of soil erosion through shallow trenches to address sheet erosion and gully plus to arrest gully erosion
  5. Natural support for naturally recruited juvenile plants
  6. Collection and dispersal of grass seeds in barren patches with no pre-existing grass cover to create structure for ongoing natural regeneration of other species
  7. Collection and dispersal of seeds of tree and shrub species to fill key species’ gaps observed after 4-5 years of assisted natural generation.

All activities are carried out manually with simple hand-held tools, without the use of heavy machinery. This is to avoid collateral damage to existing vegetation and seed banks. Also, the water harvesting mechanisms are intended to be short-term, with the trenches getting filled with soil in 12-15 months with no permanent impact.

Fig 3 a&b. Examples of measures to reduce gully erosion through water retention structures indicating bits efficacy in accumulating top soil  and slow release of moisture.

Fig 4. Such measures over a period of time revive grass cover and surrounding vegetation

Fig 5. Trenches along slopes have helped harvest moisture, recruit seeds and allow for vegetation to revive.

Fig 6. Small ponds manually constructed in appropriate locations have helped collect and percolate rain water and also attract wild herbivores and predators. Herbivores have been effective in dispersing seeds

Monitoring

  1. Restoration plots are typically 25 hectares in size. Each plot undergoes baseline assessment at the start of restoration efforts. Annual surveys are carried out to assess improvement in vegetation diversity and abundance, as well as to assess extent of re-emergence of invasive species.
  2. A comprehensive vegetation survey of several plots combined is carried out once in 5-6 years. This is done with the help of independent, external experts.
  3. Evidence of presence of fauna is recorded periodically.
  4. One round of surveys has been completed with local villagers to collect feedback about the changes, if any, in the pattern of elephant raids on farms post restoration
  5. Participation and earning levels of community members is monitored.

Results to date

Floral diversity in plots under restoration for over 5 years show good revival, with over 350 native plant species across multiple plant habits indicating good structural diversity representative of the ecosystems. Around 1200 hectares have been taken up for restoration in the last 15 years across two sites, consisting of contiguous plots at each site. Around 50% of the plots show revival of plant cover at around 60% of reference models. The plots show excellent rewilding, with return of almost all taxa of fauna. Over 60 indigenous community members from 6 villages are active partners in the restoration efforts. Income levels have doubled compared to pre-restoration levels. Participation across age groups help transfer of Traditional Ecological Knowledge (TEK)  to younger generations.

These measures have helped the ecosystem restore to a trajectory where much of the lost biodiversity and abundance is regained, with landscape having ample grass-cover and shrubs in between trees.

Fig7 a&b.These measures have helped the eco-system restore to a trajectory where much of the lost biodiversity and abundance is regained, with landscape having ample grass-cover and shrubs in between trees.

Fig 8 a&b. Examples of regions with moderate density lantana (top) restored through cut root stock method that reduces reappearance of Lantana, and allows for regeneration of native vegetation.

Lessons learned and future directions

Lessons learned from restoration activities at the site include:

  1. Taking up plots contiguous to each other facilitates natural regeneration by progressively creating a larger nucleus of native plant material.
  2.      Natural regeneration at the site was     largely based on in situ seed banks and seed dispersal from proximate areas – but       we also observe species that are not seed-bank forming coming back with no seed-bearing adult trees within a 10 sq km. This indicates that the potential for natural regeneration is significantly higher  than expected in areas with long-range seed dispersal agents and pathways.
  3. Assisted natural regeneration is about a fifth of the cost of our earlier reintroduction efforts. This helps restore significantly larger areas within the same amount of available funds. This is a key enabler for landscape-level restoration.
  4. Assessing natural regeneration potential of plots prior to commencement of restoration activities is critical.
  5. Naturally recruited plants have established better than planted ones and their presence demonstrates potential for future recruitment and recovery from disturbances.

 

Stakeholders

We would like to thank our sponsors who have come forward to support longer-term restoration activities, mainly GE India, L&T Technology Services, TTK Healthcare, Ashirvadam Foundation, CPC Diagnostics, etc.