The loss of biological and soil resources from ecosystems across the world has been documented in several forums and multiple national and international agencies have been formed to try and address this global issue. Efforts to reverse degradation through ecological restoration have come a long way, including the development of Restoration Ecology as a scientific discipline separate from Conservation Biology (1). However, as restoration efforts have gathered pace across the globe, they have unfortunately also been characterized by unclear objectives, limited indicators of success, and poor reporting of outcomes, especially on the African continent. This in turn hampers efforts to plan for future restoration projects, since practitioners are not always aware of what specific interventions have worked, and the specific contexts within which they worked.
Restoration ecologists have put in a lot of work looking at where, what, and when to monitor when it comes to restoration projects. Most commonly this involves assessing ecosystem structure (vegetation and soil composition) and function (ecological processes like water and nutrient cycling). Monitoring the changes in these factors allows practitioners to assess whether restoration objectives have been met. These assessments are not often carried out in the real world, and where they are, it often only happens for the first few project years. This can lead to land managers missing long term changes or assuming success where effects only last a short time.
As important as it is to identify what changes projects have led to in the ecosystem, it is also just as important to understand why these changes have happened how they have. Different factors could influence the success or failure of a given project, including selection of poor restoration methods, poor rainfall, damage by animals, or even poor choice of restoration location. Providing context for success or failure of a restoration project is critical for informing future restoration efforts.
One often overlooked strategy for contextualizing restoration outcomes is the use of Land potential. Land potential is basically the ability of land to produce specific kinds and amounts of vegetation, resist degradation, and recover after restoration (2).
Long-term land potential is influenced by three main landscape factors. The first is various soil properties, including mineralogy (what minerals are most dominant in the soil as a result of how it was formed), texture (the amount of sand, silt, or clay in the soil), and how deep the soil goes. The other main landscape factor is topography, basically how sloped the land under management is, which will affect water flow and therefore the potential of the land to produce vegetation. Finally, the climate of the area, specifically the amount and intensity of rainfall, will affect its ability to produce vegetation and respond to vegetation. This is important information because land potential will influence how different land areas will respond to different management decisions and restoration activities.
Knowing the land potential of an area will be very important for restoration practitioners to know if they want to set up control or reference areas for a restoration project. Reference areas are undegraded areas that one is trying to return a landscape to looking like, so they act as a target state for restoration. Control areas on the other hand are degraded areas that are not restored so the land manager can use it as a comparison of their efforts at the end of the restoration project. For both of these, the only way to ensure that any comparisons made are relevant is to make sure that the restoration, reference, and control sites are identical or comparable with regards to their ultimate land potential.
Finally, land potential is a great option to interpret restoration outcomes. This is especially important where the same restoration method has had varied outcomes across different restoration sites. Collection of land potential information before a project is started could help identify some of the reasons why restoration objectives may not have been achieved and allow the restoration practitioner to modify or discard the particular strategy being employed. For example, a gully ‘healing’ project in Westgate conservancy that kept failing was determined to have low probability of working since there was severe degradation in the upslope areas, which meant that any rainfall that fell there made its way to the restoration site with nothing to slow it down. By the time this run-off would get to the site, it was moving too fast for the restoration barriers to work properly.
Overall, there is therefore a need to provide Restoration practitioners with the necessary tools to use land potential information to better evaluate restoration outcomes, understand restoration success, and therefore inform future restoration efforts. Below, I highlight the main messages of one framework that can be used to evaluate and monitor restoration outcomes, identifying steps where land potential information could be used to provide context and inform future efforts.
Initiating monitoring before starting Restoration activities
If restoration planning is happening before restoration activities are carried out, this provides the land manager an opportunity to carefully select objectives, and properly design the monitoring plan. This level of planning allows the design of a Before-After Control-Impact experiment.
If the nature of the disturbance/treatment does not lend itself to selection of a control area (e.g., in the case of a vast wildfire where the entire affected must be treated), then the restoration practitioner can compare information on specific indicators of interest before and after restoration has been carried out, in a Before-After sampling design. In the Before-After set-up, the manager has the opportunity to collect data on the status of a piece of land before the restoration project, carry out the project, and then collect data on the status after a particular amount of time has passed. This allows one to directly contrast changes without the influence of varying land potential. In this scenario, the main considerations for any analysis is ensuring the Before-After datasets are collected during similar rainfall seasons. It would be incorrect to collect ‘Before’ data in the dry season and ‘After’ data in the wet season, as that would give a false sense of success, and vice versa.
Crucially, if only a descriptive record of changes due to restoration is desired, then fixed point ground based or aerial photography may be sufficient to provide the required information.
In the Control-Impact set-up, the land manager selects paired treatment and control plots from within the degraded area. Only the treatment plots are restored, with the controls being left untouched for future comparison. Land potential is extremely important in this design as it ensures that the treatment and control plots are true matches with regards to the factors that are likely to influence restoration outcomes. Depending on the natural variability of an area and the type of restoration, the components of land potential that will be most important might vary. For example, if the restoration project is aimed at reversing compaction in an area, soil texture and bulk density similarity between treatment and control areas will be a more important matching criteria than climate or nutrient availability. By collecting information on land potential and making sure it is similar between treatment and control areas at the time restoration is implemented, the restoration practitioner can be sure that the treatments implemented would conceivably have had the same effect on both plots.
Initiating monitoring after Restoration activities
Retrospective assessments of restoration projects are often the only way to monitor large scale restoration projects that are implemented outside the formal restoration experiments, especially in Africa. Like monitoring before Restoration begins, retrospective selection requires careful matching of treatment and candidate control sites.
Matching of long-term land potential through relatively unchanging soil properties like topography, and climate could likely be accomplished without much difficulty. However, the status of short-term land potential is influenced by relatively dynamic soil properties and vegetation cover and composition, which requires some historical knowledge of the treatment and proposed control areas at the time treatments were done. In this case, best estimates of physical similarity at restoration should be obtained from multiple sources, and any results obtained should be looked at with care.
One important possible source of this supplementary information is the restoration practitioners themselves, as well as other land managers and land users with historical knowledge about the landscape in question. Historical imagery from ground, aerial or satellite images could also be instrumental in assessing biophysical similarity at the time of restoration.
Selecting indicators for monitoring
Many frameworks have been developed that suggest the types of indicators that need to be collected, covering both ecosystem structure and function. Our framework identifies three key ecosystem attributes, namely hydrologic function (water retention and cycling), soil and site stability, and biotic integrity (vegetation composition and condition). Within these attributes, 17 different qualitative indicators are suggested, some contributing to multiple attributes.
The selection of indicators to be assessed will ultimately depend on the restoration objectives, type of disturbance, restoration method, as well as the skill level and resources of the restoration practitioner themselves. For example, if a project is focused on reducing surface run-off and increasing water infiltration into the ground, basic information on ground cover would be sufficient, with more emphasis placed on indicators measuring soil stability and water flow integrity.
Use of a Mobile App (LandPKS) for Land potential analysis
The ease of use and availability of Smartphone connectivity, even in rural Kenya, allows land managers to take advantage of Mobile phones to help with Land potential Analysis and vegetation data collection.
The Land-Potential Knowledge System (LandPKS) is a global mobile phone application supported by cloud computing that was created with the aim of providing simple tools for collecting, storing, and sharing scientific and local knowledge to inform and support decision making for sustainable land management.
This app also allows access to global climate and soil datasets, as well as a cloud-based data storage and access portal. It allows rapid collection of important rangeland indicators even by minimally trained assessors. LandPKS modules do not require access to the internet for data collection, but do require access to the device location function, as well as a data connection for backup of plot information and access to climate data. The simplicity of this system and the large number of response variables it captures makes it an ideal rapid assessment environment that can be adapted for restoration evaluation.
The LandInfo module allows users to collect information on site characteristics related to long-term land potential, most importantly slope and slope shape, as well as soil texture and depth, all of which are critical for determining land potential and therefore instrumental in matching treatment and control plots. More information on the actual use of the apps can be found here and here. After entering information on slope, slope shape, as well as soil texture and depth, LandPKS provides the user with site specific climate and plant available water holding capacity (PAWHC), an umbrella metric for plant productivity capacity. It also predicts soil type based on location and user inputs. This summary of user inputs and system outputs can be used to compare the selected treatment plots to candidate control plots, allowing for selection of the best matching ones.
The LandCover module is focused on collection of vegetation data, including plant cover, bare ground cover, and the relative cover of different plant groups like trees, grasses, or annual plants. It is a modified Line-point intercept based on a methodology originally designed for use in East African rangelands (3). The app also guides the user in estimating the proportion of large gaps between plant bases as well as between plant canopies.
The LandPKS system allows collection of indicators that assess all three of the basic attributes suggested in the framework (hydrologic function, soil stability, and biotic function) and supplementary data can be added depending on the focus of the restoration project.
Our suggested framework is only partially prescriptive and does not deal with selection of restoration strategies. Additionally, our framework is only meant to facilitate rapid assessment and incorporation of land potential evaluation, especially on landscapes where restoration practitioners are unlikely to have the time or resources to undertake more in-depth evaluations. Finally, landscape level processes are only partially addressed within the structure of the framework and are not explicitly measured in the overall decision tree aside from when interpreting restoration results.
The main take-aways from our suggested Framework are as follows:
-Evaluation of Restoration outcomes is important to help land managers and restoration practitioners gauge Restoration success and to inform future restoration efforts.
-Land potential information is instrumental for designing successful restoration treatments, however it can also be used to improve treatment monitoring design and evaluation efforts
-LandPKS is a mobile phone application that can be used to both help estimate land potential as well as collect monitoring data, potentially reducing the costs for both
(1) Young, T. P. (2000). Restoration ecology and conservation biology. Biological conservation, 92(1), 73-83.
(3) Monitoring of Rangeland Health Manual. Riginos and Herrick 2010.
(4) Kimiti, D. W., Ganguli, A. C., Herrick, J. E., Karl, J. W., & Bailey, D. W. (2020). A Decision Support System for Incorporating Land Potential Information in the Evaluation of Restoration Outcomes. Ecological Restoration, 38(2), 94-104.