2021-2030 is the United Nations Decade on Ecosystem Restoration. The debate around ecological restoration has been going on for a few decades now, the reason being that ‘we are using the equivalent of 1.6 Earths to maintain our current way of life’[1] and this fact was recognized, much to the dismay of several stakeholders. Farmlands, forests, freshwater, grasslands, shrublands, savannahs, mountains, oceans and coasts, peatlands and urban areas[2], which form a comprehensive categorization of our ecosystem, are undergoing an unprecedented change caused by a combination of factors, but experts have been unequivocal in their view that economic growth has damaged the ecological health of our planet in several parts.
An ecosystem comprises all living organisms; their physical environment and the interaction between the two in a defined space. It consists of abiotic constituents (minerals, climate, soil, water, sunlight) and biotic constituents (all living members).[3] These two are linked by the flow of energy and through nutrient cycling within the system. The various trophic levels in the ecosystem play their respective roles and create a complexity that naturally constructs the ecosystem.
Autotrophic organisms (referred to as the producer level – plants), can make their own food using the energy of the Sun, through the process of photosynthesis. They convert carbon dioxide and oxygen into carbohydrates and produce more complex compounds such as proteins and starch. Heterotrophic organisms depend on autotrophic organisms, directly or indirectly; as they are consumers and can’t make their own food. Animals and bacteria fall into this category. The Food chain, that we know, is flow of energy and organic matter through each of these levels (producer and various consumer levels) and what emerges is a wonderful complexity and interdependency in nature.
Now let us once again come back to the point of how economic growth has damaged ecological health of our planet. A minor degression away from science here, how should economic progress be evaluated going forward? Shouldn’t we consider natural wealth – the bounty that nature has been giving us? Natural Capital (accumulated wealth of nature) refers to the fixed stock of physical and biological elements found on Earth and contains both renewable and expendable resources[4]. It is important to pause here and categorize natural capital[5], because we need to understand what we are trying to restore:
- Renewable (well-functioning ecosystem and biodiversity)
- Cultivated (crop varieties and livestock races)
- Replenishable (clean air, potable water and fertile soils)
- Non-renewable (petroleum, copper, coal)
Ecological Restoration (ER) is the process of assisting the recovery of an ecosystem that has been degraded, damaged or destroyed[6]. From the point of view of science, this is done biologically, structurally and functionally[7] and we will touch on a few definitions in this regard, a little later. But what must be appreciated is that ER includes all practices and ideas which help in restoration, be it scientific, social, political or economics-related. There are other aspects of ER that become important: it should ensure that ecosystem resilience is sustained; it should conserve biodiversity; it should ensure greater adaptability of species (plant or animal) within the ecosystem and should provide benefits to humans in a sustainable way.
Restoration Ecology is a field of science which is specifically concerned with restoring ecosystems. An interesting field of study because its practical value can be readily tested and its relevance can be questioned on a vast scale due to the looming ecological imbalance issues in the world currently. Arguably, never has there been such pressure on a scientific discipline to deliver practically.
This field is seen as being structured well, with a) guidelines for restoration goals and measuring success; b) models of restoration processes and c) frameworks for the field[8]. Guidelines for practical restoration are also available based on empirical evidence, for various ecosystems. Science plays a central role in the following example of a suggested framework (we take restoration of a flora habitat as an example here[9]), which would include:
- Setting targets and planning for success based on site environmental attributes. A reference point (site) needs to be articulated for measurement of species richness and density, habitat structure and function.
- This would include choosing metrics, survey techniques and tests to monitor restoration vis-à-vis reference site.
- Ecological succession is a process in which the structure of a biological community evolves over time, creating a changing mix of species[10]. Factors such as species richness, etc change over time due to succession and restoration so this also has to be factored in while setting targets.
- What materials, seeds are needed to ensure a habitat is restored; creation of species list with targets for planting and seeding density are some more aspects to consider.
- Sourcing plant material – allow species to naturally regenerate/through natural dispersal process or source material externally (keeping in mind that species are spatially genetically structured).
- Optimizing plant establishment – Ensuring germination of seeds (a problem area that needs extensive research). Several scientific procedures are possible to enable this process.
- Facilitating plant growth and survival – Light, temperature, humidity and wind are all factors that impact this phase. Techniques to reduce wind and airborne particles, shading of plants to reduce stress from evaporation and ensuring soil surface stability are all possible.
- Sustainability, Resilience and Landscape Integration – This will finally determine whether the restoration has been successful or not. Stress conditions can be imposed to check for resilience. Sustainability can be judged primarily from the ability of populations to survive over generations (which makes long-gestation restoration studies so important). Another important aspect is including fauna communities, for the value that they provide and also for important functions they perform in areas of pollination, seed dispersal, nutrient cycling and herbivorous activity.
Ecosystem Services, benefit all of us humans. These benefits occur to us through the natural ecosystems and those that are managed. The services that we receive and some examples are[11]:
- Provisioning (food, fodder, firewood)
- Regulating (water regulation, waste recycling, flood prevention)
- Cultural (Knowledge, recreation)
- Supporting (Soil formation, Nutrient and Water Cycling and food chain process)
Science can be used widely in ER on 2 levels: 1) Understanding science, to let the natural process(s) function, untampered and 2) Systematically using science, scientific principles and technologies to restore
An Example: Understanding science in Forests[12]
Tropical forests affect the quality, storage and delivery of freshwater. Forests reduce sedimentation and erosion. Trees restore water to the atmosphere and while doing so, remove all pollutants. Leaves on the ground, microbes, soil and vegetation, all remove or biochemically transform contaminants during the infiltration of water to the ground. Replacing forests with plantations drastically reduces water quality and therefore we find several regions which protect their upland watershed areas (eg: ecological reserves of grasslands and cloud forests[13]). More importantly, there has been a view long held that forests consume more water, depriving other users, even humans, of water. While forests use water, this is only a lopsided view as, evapotranspiration results in rainfall in a different area. Nature has a way of giving back, which majority of mankind is yet to fully fathom and appreciate. The amount of precipitation which came back to recharge ground water was up to 70% for natural forests in the Western Ghats. Forests also seemed to retain and then release water during the dry season.
Now, take the example of Riparian forests (forests along waterways). They regulate temperature in streams, they reduce soil erosion and sedimentation (both factors affect fisheries) and fish get their food from leaves, fruits and seeds that drop from the forests, sustaining marine life.
The importance of mangroves cannot be overstated. They store very high levels of carbon and also perform a cleaning function where organic material travelling in waterways are held back by them and prevent damage to marine life. They also prevent large tides and small-scale tsunamis.
Climate changes impact the temperature of water; how organic material decomposes; food available to marine life; level of oxygen in the water and eventually may make coastal water saltier. Just allowing the ecosystem to function in a natural way, by acting responsible at all levels, will ensure further degradation is stopped.
Take the example of biodiversity and ecosystem function. A global study conducted[14] with samples from all continents (except Antarctica) showed that plant species richness in dry-lands (41% of Earth’s land surface), enhances their multifunctionality. That is, there is carbon gain, carbon storage and nutrient cycling. In drylands, important ecosystem services include: conversion of solar energy, CO2 in the atmosphere and water to plant biomass; carbon storage and nutrient cycling. This can prevent desertification and enable carbon sequestration. Such knowledge can not only guide restoration efforts but educate citizen scientists on how to preserve what we have in dry-lands.
What about areas that have already been degraded? Here science, can play a proactive role[15]:
- Reforesting degraded land, can lead to increased transpiration and water tables reach safe levels (to reduce dryland salinity). Doing this in upper watershed areas, where groundwater recharge is occurring would be preferable to the plains, where saline water is being discharged.
- Multispecies forests, which are structurally complex and deep-rooted can ensure soil erosion control; water supply and regulation and filtration of water for use in other purposes
- Uneven-aged, self-sustaining and multi-species forests can lead to carbon sequestration and carbon storage in the long-run
- A large population of plant species and required fauna can ensure pollination
- For habitat conservation and restoration (flora and fauna), there may be use of native species, with flowering and fruit cycles that support native population
Active and Passive Restoration and Science Education
By understanding the science behind our ecosystem, we can engage in passive restoration at an individual level as well, by altogether removing or lessening those factors which damage our ecosystem and also monitoring that it has returned to a healthy state[16].
Therefore, one of the UN Decade goals is to “apply knowledge of ecosystem restoration in our education systems and within all public and private sector decision-making”. One of its Key Messages is also increasing awareness of the importance of healthy ecosystems across the educational systems. Clearly science education can become hugely relevant in this respect.
Active Restoration suggests removing deleterious factors and accelerating the process of recovery. Needless to say, active restoration can be risky if not backed by significant scientific research and monitoring over a significant period of time. Which is why, this debate of passive vs active restoration continues in the field of restoration ecology.
Key Questions in Restoration
Ecological Restoration has to address a very important scientific question to progress in a direction where it meets with maximum success: Should we recover and revive lost or degraded habitats to extant or historical states? OR – Should we reinforce or redefine for future conditions. To what time point should we restore?[17] Since success rates in restoration, across the wide variety of initiatives, is not as encouraging as required, some of these suggestions have naturally emerged.
Here science could play a very critical role, as emerging genetic technologies can result in restoration which adapts species to future environmental conditions. Synthetic biology and gene editing tools (CRISPR/CAS9) can create and spread engineered and beneficial genetic elements within endangered populations for assisted adaptation.[18] This increases resilience of species and could possibly prolong their existence in general. We have already given a definition of ER but strides in this young science are making people revisit that definition to see its various implications.
- Recover – Restoration that replicates unknown genetic baselines. Marine restoration has typically happened without empirical genetic data. The focus has been to primarily restore habitat structure, functions and biodiversity. Having said that, general genetic principles have been used such as mixing population to avoid in-breeding and ensuring diversity; genetic baselines have been arrived at using related taxa (unit of biological classification) and so on.
- Revive – Restoring extant or historic genetic baselines. Restoration programmes should at least try to replicate natural genetic baselines based on empirical data.
- Reinforce – Improving genetic baselines for future conditions.
- Redefine – Create a novel genetic state (example of synthetic biology given above).
The last two items have strong ethical implications but can’t be completely ignored given the dynamic environmental state; large-scale human interventions in ecosystem and emergence of new ecosystems, which may make only “recover or revive” inadequate to ensure success of an ecological restoration programme.
But the ethical aspect (bioethics), may make it worthy of consideration only where species are close to extinction and have great value to the ecosystem in general. The ethical debate is, whether starting this kind of human-engineered process could lead to a further slackening in our commitment to protecting our ecosystem.
When we know there is a ready-made solution to address an evil, already committed by us, we may be tempted to use that solution over and over again and not exercise enough will-power to stop the unpalatable practice (such as habitat destruction through human activity). After all, we have not shown prudent use of nature’s bounty in the past. Further, should we be allowed to tamper with a natural process, just because we are the cause of damage? It could mean we decide, which species dominate in the environment and so on. Future being unpredictable, what future state are we going to consider for a redefinition?
The solution might be to look at historical and contemporary state of an ecosystem and also consider data specific to a particular region and forward-looking data as well (considering future environmental changes) in deciding how to ecologically restore[19]. But the final say may be that of the Regulatory framework at present, which might allow only the use of historical and contemporary state of an ecosystem as a guide for restoration.
There is no dearth of data on the impact of human activity on our ecosystems (see report of UNEP, 2021 on Ecosystem Restoration for People, Nature and Climate). The field is vast, as we can independently evaluate the impact of human activity on farmlands, forests, freshwater, grasslands, shrublands, savannahs, mountains, oceans and coasts, peatlands and urban areas (mentioned earlier). We can further see, where we stand on each of these, geographically and apply a viable framework (such as suggested earlier) to undertake restoration activities. Ecosystems are diverse and unique and demand bespoke restoration programmes.
Further, there are some other issues to consider in ER such as tapering off of recovery rates over a period of time and that some ecosystems naturally recover faster than others – all questions which science can investigate in great depth as part of future research work. In this article we have attempted to delineate the relevance of science to this field and how science can help reverse the damage to our ecosystems. We believe that restoration ecology, being a young and very relevant science, globally, can be a highly engaging field for science students.
Here is a list of terms from the article that you may want to look up: Watershed (multiple meanings based on context!), Evapotranspiration, Carbon Sequestration, Genetic Baseline, Bioethics
[1] Ecosystem Restoration for People, Nature and Climate, United Nations Environment Programme, 2021
[2] Categorization by UNEP, 2021
[3] Britannica.com/science/ecosystem
[4] S.Alexander, J.Aronson, O.Whaley and D.Lamb, The Relationship between Ecological Restoration and the
Ecosystem Services Concept, 2016
[5] Millennium Ecosystem Assessment (MA 2005)
[6] Most accepted definition by the Society for Ecological Restoration in their Primer cited in D.M.Martin,
Ecological Restoration should be Redefined for the twenty-first century, 2017
[7] 1987, Berger, Restoring the Earth
[8] B.P.Miller et al, A Framework for Practical Science necessary to restore Sustainable, Resilient and Biodiverse
ecosystems.
[9] ibid
[10] Britannica.com/science/ecological-succession
[11] Millennium Ecosystem Assessment, 2005 cited in S.Alexander, J.Aronson, O.Whaley and D.Lamb, The
Relationship between Ecological Restoration and the Ecosystem Services Concept, 2016
[12] K. Brandon, Forests and Freshwater, Ecosystem Services from Tropical Forests, 2014
[13] Found in mountainous regions, with heavy rainfall and condensation with cover of clouds
[14] G.F.Midgley, Biodiversity and Ecosystem Function, 2012
[15] S.Alexander, J.Aronson, O.Whaley and D.Lamb, The Relationship between Ecological Restoration and the
Ecosystem Services Concept, 2016
[16] J.R.Rohr et al, The Ecology and Economics of Restoration: when, what, where and how to Restore
Ecosystems, 2018
[17] M.A.Coleman et al, Restore or Redefine: Future Trajectories for Restoration, 2020
[18] ibid
[19] H.P.Jones et al, Restoration and Repair of Earth’s Damaged Ecosystems, 2017
