Techniques used in ecological restoration of plant communities do not have uniform outcomes

When dealing with degraded ecosystems in agricultural landscapes, livestock exclusion is often the first step in restoration. However, the outcomes of fencing are usually varied; it does not guarantee the desired effect. A slow transition to desired states or towards undesirable states could suggest legacy farming poses ecological barriers inhibiting the regeneration of native species. In general, such variability in recovery can be related to site productivity, level of degradation, and soil conditions. In a study by Sims et. al (2018), responses to fencing in terms of divergence from initial states and convergence with targeted states that represent restoration was analyzed in grassy woodlands in Australia. Using a conceptual model, they found little evidence to suggest fencing encourages convergence to reference plots (Figure 1). They found evidence to suggest species composition of fenced plots diverged from unfenced plots, however it was highly variable among sites and unrelated to the time since livestock was excluded.

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Figure 1. Unconstrained model-based ordination for changes in vegetation composition. From what I can gather, fenced plots are more closely related to unfenced plots rather than reference plots over the 17-year study duration. Source: Sims et. al (2019)

Thus, this study highlights the importance of site selection, as livestock exclusion may gain the desired effect of returning to an initial state (soil and species compositions) but it isn’t guaranteed. In a broader sense, there is no one-size-fits-all solution to very similar problems, as these are more complex than we think. For example, in a study by Gomez-Aparicio (2009), it was asked whether the benefits of facilitation as a restoration tool varies based on study duration, life-form of the neighbour, and target species. Indeed, herbaceous communities provided more inhibition than facilitation whereas shrub communities were the opposite. So facilitation really does not work in all cases, just like livestock exclusion doesn’t either, and management practices should be site-specific.

References

Gómez-Aparicio L. The role of plant interactions in the restoration of degraded ecosystems: a meta-analysis across life-forms and ecosystems. Journal of Ecology. 2009;97(6):1202–1214. doi:10.1111/j.1365-2745.2009.01573.x

Sims RJ, Lyons M, Keith DA. Limited evidence of compositional convergence of restored vegetation with reference states after 20 years of livestock exclusion. Austral Ecology. 2019. doi:10.1111/aec.12744

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How ancient agricultural landscapes can affect current forest structure

Agricultural productivity has no doubt increased significantly in recent times, but not without a multitude of negative ecological impacts on agricultural systems. These include carbon sequestration, nutrient cycling, soil composition, water purification, and pollination all being affected. Such ecosystem services are amplified by biological diversity; in Europe, 50% of all species depend on agricultural habitat (Stoate et al. 2009). Not to mention, habitat destruction due in part to agriculture is a growing concern in terms of biodiversity.

However, current agricultural production is not the only way to change current landscapes. Ancient land-use legacies can have a profound impact on the landscapes that we see today. It is now known that prior to European colonization, areas that were thought to have been pristine or untouched actually had been significantly altered by ancient humans. Evidence suggests vast tracks of forests had been cleared for agriculture or burned by ancient humans prior to European arrival in the Americas. Thus, the concept of “virgin” forests is now obsolete in many instances. Afforestation, or planting trees on barren land to create a forest, is then a common response to abandoned agricultural fields.

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Figure 1. Terraces.

An example of ancient land use legacies continuing today is found in Central America with the Maya civilization. Left behind by the Mayan’s was an extensive network of agricultural terraces that still persist today underneath the dense forest canopy. Terraces are levelled surfaces built on hills, like steps, for the purpose of more efficient farming (Figure 1). In a very interesting study, Hightower et al. (2014) aimed to determine how forests growing on terraces were different from forests on non-terraced land. Here, they found forests growing on agricultural terraces had taller, more closed, more vertically diverse forests. These variables increased with increasing slope (Figure 2). To be more exact, with steeper slopes, terraces yielded ~8% taller, ~20% more closed-canopy, and ~7% more vertically diverse forests. Thus, even though this site in Belize was abandoned over 1000 years ago, ancient Maya agricultural practices still influence current forest structure today.

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References

Hightower J, Butterfield A, Weishampel J. Quantifying Ancient Maya Land Use Legacy Effects on Contemporary Rainforest Canopy Structure. Remote Sensing. 2014;6(11):10716–10732. doi:10.3390/rs61110716

Stoate C, Báldi A, Beja P, Boatman N, Herzon I, Doorn AV, Snoo GD, Rakosy L, Ramwell C. Ecological impacts of early 21st century agricultural change in Europe – A review. Journal of Environmental Management. 2009;91(1):22–46. doi:10.1016/j.jenvman.2009.07.005

 

The Importance of Restoring Plant Communities

Ecological restoration of plant communities is meant to restore lost biodiversity, primarily through recovering the original plant communities rather than increasing the number of species.  The number of species associated with degraded environments would in turn also have to be decreased.  Restoration efforts of plant communities include less expensive methods through modifying abiotic factors, such as soil and water.  More expensive methods involve biotic modifications that include reseeding or replanting native species from local sources, and removing invasive species through mechanical means or herbicides. 

Protecting the environment is the government’s responsibility.  The omnibus C-38 bill passed by the Harper government negatively affected various aspects of environmental protection.  The Canadian Environmental Assessment Act was replaced with a new act limited to fish and aquatic species, and the Species at Risk Act for birds.  The Canadian Environmental Assessment Agency was also affected, having only 45 days after receiving an application to decide if an assessment is required.  Environmental assessments are not required; instead the minister is given the power to decide.  Another act negatively affected was the Canadian Environmental Protection Act.  Current 1 year limit permits for disposing waste at sea can be renewed up to 4 times, and the 3 and 5 year limits protecting species from industrial waste will have no limits. 

There are many important reasons for ecosystems restoration including helping threatened or endangered species, lessening the effects of climate change, restoring natural resources, or simply to mitigate the extinction of experience for humans.  In order for this to happen however, new acts which increase the reach of restoration efforts have to be passed.  This is the responsibility of the new generation of scientists and politicians. 

Negative Effects of Agriculture on the Environment

Agriculture is a vital part of our current way of life, however current agricultural practices have had numerous negative effects on the environment and surrounding habitats.  Forests have to be cleared in order to provide space for agriculture.  This destroys the forest ecosystems and also contributes to climate change due to forests acting as carbon sinks.  Other agricultural processes release greenhouse gases including carbon dioxide as well.

The removal of trees can cause water to evaporate faster due to the lack of shade, and in addition to the other pollutants, negatively affect the water quality.  The lower water quality then affects the rest of the ecosystem that relies on the water, as well as humans.  Uneven irrigation can result in under irrigation of soil some areas which causes increased salinity, killing the plants.  Over irrigation can cause more nutrient and chemical runoff, which also affects water quality.   Water can also erode the topsoil, causing a decline in the soil quality.  Other factors which negatively affect the soil quality include chemicals from pesticides and improper waste disposal.

In order to reduce the impacts on the surrounding environment, sustainable agricultural practices need to be implemented.  Soil is the most important aspect in ensuring crop growth.  Methods to preserve soil quality include installing windbreaks to reduce wind erosion, low-till or no-till farming to avoid water evaporation and retain nutrients, and composting also helps to reintroduce nutrients back into the soil.  Another method includes reducing the use of chemical fertilizers and growing a number of different crops in the same field so that the legumes can naturally restore nutrients in the soil each season.  This also helps with monocultures of crops, which are susceptible to diseases.  Measures need to be put into place to ensure there can be enough food produced as human populations increase and the need for available farmland increases as well. 

Saving Private Garry

Ecological restoration is the recovery of habitats and ecosystems back to their original states. Restoring plant communities can increase biodiversity. Currently, biodiversity is rapidly decreasing throughout the world due to many factors such as climate change, pollution and loss of habitats. In Canada, some natural areas are protected by the government, but these ecosystems can still be vulnerable to degradation. Thus, a 3-step guide was created in an effort to restore protected areas as effectually as possible.

Fort Rodd Hill National Historic Site is located in Colwood, British Columbia. This location houses one of the last remaining Garry oak ecosystems. This ecosystem does not only comprise of Garry oaks, but many plant, animal and insect species, as well. Fort Rodd Hill also contains 7 plant species that are at risk of extinction, which makes protecting this site a priority.

A Garry Oak tree

Years ago, fire was used to control the ecosystem by the Aboriginal people. Now, fire is being used less, which is bad news for the Garry oaks. With fire being restricted, it makes it easier for species like the Douglas fir to quickly grow to big heights. Slow-growing trees like the Garry oaks suffer as a result when the Douglas firs block sunlight.

The first step in the guide to recover ecosystems is the “effective restoring and maintaining of ecological integrity”.  In the Garry oak ecosystem’s case, over 12 tonnes of Douglas fir trees were removed by 2004. Also, 10,000 native plant seeds were collected and grown in protected sites with Garry oaks surrounded by a fence to prevent animal grazing. The second step in the guide is “efficiently using practical economic methods to achieve success”. Invasive species control methods were created by collaborating staff members and an ecosystem recovery team. The last step is to “engage through implementing inclusive processes by embracing interrelationships between culture and nature”. After removing the invasive Douglas firs and helping the Garry oaks, the volunteers and staff were proud that their hard work led to an ecosystem being saved. Their efforts will encourage future generations to continue restoring endangered ecosystems.  

If you want to learn more about Canada’s effort to conserve and restore ecosystems, check out: https://www.pc.gc.ca/en/nature/science/conservation

Restoration and the future of ecology

As the human population begins to surpass the 7 billion mark, the requirements and thereby, stressors, on the natural environment are continuing to grow [1]. We are beginning to see increased threats on plant continuity and their ecological capacities, goods and services. Ecosystems are progressively worsening, to the point where they will be incapable of sustaining life on earth [1]. Thus, ecological restorationefforts are critical now, more than ever. Ecological restoration is the practice of recovering and renewing damaged, destroyed and/or degraded ecosystems and habitats in the environment by active human mediation efforts [1].

An example of such efforts is well depicted in 1969 – at what is now recognized as being the Selah, Bamberger Ranch Preserve in Texas. At the time, the land was in terrible condition; the ground was barren, there was a plethora of Ashe juniper trees –prohibiting sufficient water distribution all through the territory, hindering the growth of other plants and grasses [2]. Further reducing the abundance of animal life in the area. Nevertheless, decades of hard work to eradicate the Ashe juniper, introducing native grasses/plant life, and performing land restoration work has aided in a remarkable transformation of the once barren land [2]. Now, not only is the land home to an array of plant and animal species, but a running stream has been able to establish across the land – providing a necessary water source to sustain this diversity. This just shows what impeccable transformations can be made through dedicated restoration efforts [2]!

References:

[1] Ecological Restoration. (n.d.). Retrieved from https://www.bgci.org/plant-conservation/restoration/

[2] 2 Examples of Ecological Restoration to Inspire Students at Environmental School. (2017, June 20). Retrieved from https://online.unity.edu/2-examples-ecological-restoration-inspire-students-environmental-school/

The Future of Ecological Restoration

Ecosystems are being used unsustainably worldwide, and many are at risk of being lost forever. In many parts of the world, ecosystems are no longer providing essential services, such as food and water production, climate regulation, carbon storage, crop pollination, and wildlife habitat. But something can be done.

Ecological restoration is known as the process of assisting the recovery of an ecosystem that has been degraded, damaged, or destroyed. However, this definition does not incorporate social aspects and public inquiry of ecosystems. Not only should restoration restore environments and ecosystems that have been destroyed by restoring certain targets, ecological restoration should also be improving social and life sciences. Currently ecological restoration includes recovering biodiversity, species composition, community structure, and ecosystem resilience, but it should also include social goals such as empowerment of local communities, and improving conservation strategies.

In order to do include both social and scientific aspects of ecological restoration a new definition is needed.

Ecological restoration is the process of assisting the recovery of a degraded, damaged, or destroyed ecosystem to reflect values regarded as inherent in the ecosystem and to provide goods and services that people value.”

David Martin, 2017

This definition shifts decision‐makers, scientists, and other restoration professionals to follow a structured goal setting process in which they can design their restoration policies and/or practices. This new structure forces restoration professionals to think based on values the ecosystem has, both biologically and socially (human). Using this approach, restoration professionals are encouraged to decide what they cared about first, the “why”, and then later going about doing it. By using this structured method, restoration professionals could allow their work to directly connect appeal with promise, and we may discover a more powerful goal‐setting structure for ecological restoration.

Hierarchical Structure of Ecological Restoration. Professionals should begin at the “why” (top) and work their way down to the “what” (bottom). The “why” is what they want to restore and the “what” is how to go about doing so.

Above is the hierarchal structure of how professionals should approach restoration goals. Breaking the goal‐setting process down into parts has advantages:
(1) it allows the process to be more transparent and documentable, which could control for unintended costs or restoration failures
(2) it allows for roles to be clearly defined, which could control for scientists inserting normative preferences into the process
(3) it allows for multiple potential goals and objectives, including associated ecosystem and social attributes.

The future of restoration is strong, especially if we include every community and many different factors in saving ecosystems. Although biology and science are the leading reason for restoration, every community can be involved with this new structure. This gives us promise for saving ecosystems, biodiversity and natural landscapes, as everyone will want to take part to save what they love and need.

References:
Martin, David M. “Ecological Restoration Should Be Redefined for the Twenty-First Century.” Restoration Ecology, vol. 25, no. 5, 2017, pp. 668–673., doi:10.1111/rec.12554.
“What Is Ecological Restoration.” Ecological Restoration Alliance of Botanical Gardens, 2019, http://www.erabg.org/what-is-ecological-restoration/.