Habitat Fragmentation Edge Effects: When Having an Edge is Not a Good Thing

August 6, 2018 By Mark Aspelin

The following is a longer version of an article that was published on GreenBiz on 8/13/18: https://www.greenbiz.com/article/when-it-comes-habitat-having-edge-not-good-thing


We usually think it’s great when we have an edge, but that’s certainly not the case when we’re talking about habitat fragmentation edge effects and their impact on biodiversity and wildlife.  In this post we’ll explore the topic of edge effects and how it relates to business and biology.

Habitat destruction is the #1 issue that impacts wildlife and biodiversity today.  This fact shouldn’t come as much of a surprise.  When we think of all the roads, power lines, buildings, clearcutting, and other development activities taking place all over the world, we can quickly get a sense of the widespread reality of this issue.

The World Wildlife Fund estimates that forests cover about 31% of the land area on Earth and, for a variety of reasons, we’re losing about 46,000 to 58,000 square miles of forest each year – roughly equivalent to losing 48 football fields every minute.  In the Amazon alone, we’ve lost about 17% of the forest over the past 50 years, mostly due to forest conversion for cattle ranching.  Habitat destruction is clearly a big issue, and it won’t be going away anytime soon.

The term “habitat destruction” can refer to the complete destruction of a habitat or, more commonly, habitat fragmentation, where a large, continuous area of a habitat is divided into two or more fragments.  The primary culprit behind habitat loss, degradation, and fragmentation is a change in land use, usually in the form of agriculture, logging, mining, and urban or residential development.  

There are three important conditions that characterize habitat fragmentation: smaller habitat, increased edge effects, and increased isolation.  Today, we’ll focus on the second characteristic – edge effects, which refers to the effect of an abrupt transition between two different, adjoining ecological communities.

We can see examples of edge effects occurring naturally all over the place.  These natural edges, such as the forest and meadow pictured below, can lead to greater biodiversity in the area.

However, the edge effects that I’m focusing on in this post are man-made edges that are created in the middle of an existing natural habitat.  From a business perspective, habitats are commonly fragmented by the construction of roads, power lines, and buildings, or the clearing of land for agriculture and forestry.

In the context of habitat fragmentation, edge effects increase the proportion of habitat edges in relation to the total area.  In other words, any given point within the fragment of land is, on average, closer to an edge.  Why does that matter?  Edges matter because they create changes in the species composition for a given chunk of land.  These species-composition changes found at edges are caused by the following conditions:

  • Edges of a forest have microclimatic changes that impact the types of vegetation that can grow there.  These microclimatic changes include more direct sunlight, higher soil temperatures, differences in humidity and depth of humus, and increased wind exposure and snow loads compared with the interior of a forest.  The seeds of some plant species are sensitive to drying out with increased sun and wind, leading to significant differences in the types of vegetation found at a forest edge compared with the forest interior.  To make matters worse, these species alterations extend into the forest interior.  In some tropical rain forests, vegetation changes have been detected as far as nearly 1,500 feet from the edge.  In the scenario where we have a small fragment of a natural habitat or a narrow corridor of land, the microclimatic changes associated with the edges can permeate throughout the entire piece of a habitat.  The result may be a decrease in the presence of rare and sensitive species, while weedy species and generalist predators may thrive.
  • Edges are suitable for some species but unsuitable for others.  If we build a road through a forest, some plant species will thrive with the extra sunlight, and some bird species will enjoy perches next to these open areas where they can pounce on exposed prey.  “Edge species” such as deer and elk like forest edges because they can find food in open areas and take cover in the forest.  Other species of animals will actively shy away from areas of increased sunlight and exposure, moving further into the interior habitat where the characteristics of land remain unchanged.  For example, spotted owls (pictured below) prefer old-growth, mature forests with a lot of canopy and few edges.  When we push these species into the now-smaller interior habitat, we are likely to see increased competition for limited resources.
  • Edge-tolerant species are often generalist predators and exotic species that outcompete native species and habitat specialists.  Examples of edge-loving species include brown-headed cowbirds, crows, raccoons, and opossums.  These species thrive in an edge habitat and act as nest predators and cavity competitors of interior species, which can decrease the populations of forest songbirds, ground-nesting birds, reptiles, and amphibians in the remaining habitat fragments.
  • Edges become areas with increased noise, light, pollution, human recreation, and roadkill.  The increased noise, light, and human activity may cause some species to move further inland, away from habitat edges. Traffic on adjacent roads can cause pollution in the form of nitrogen deposition, and the increase in noise and light can deter or disorient animals.  Roadkill continues to be a significant source of wildlife mortality with several million collisions per year reported worldwide.  In one study in Saguaro National Park on the United States–Mexico border, an estimated 30,000 animals were killed by vehicles annually.  This included a variety of reptiles, amphibians, birds, and mammals, such as the mountain lion pictured below at Saguaro National Park.

Business Strategies for Managing Edge Effects

To address the issue of edge effects, corporations typically use one or more of the following four strategies:

Avoidance: The first—and best—strategy that companies can adopt to address edge effects is a simple one: Avoid the construction of buildings, roads, trails, power lines, pipelines, etc. in areas with high-quality habitat for species that are classified as endangered, threatened, or vulnerable to extinction.  This avoidance strategy may also be extended to a high-quality habitat for species that are classified as “species of concern,” depending on the health of the populations of those species as well as the degree and types of potential impacts.  To identify these “avoidance zones,” you’ll need to conduct a biodiversity assessment to collect data about the species that are in the areas where you hope to develop or operate.  

Minimization: For land that is not categorized as an avoidance zone, corporations shift their attention towards minimization strategies that reduce the duration, intensity, and extent of their impacts for biodiversity and wildlife.  For example, some oil and gas corporations take steps to reduce the width of land cleared for the construction of a pipeline or road.  In another example, the State Grid Corporation of China implemented an “Electricity Caravan” concept to minimize environmental impacts in a fragile plateau environment in the area of Sanjiangyuan National Nature Reserve (pictured below), known as “the water tower of China”.  This project between Golog and the main grid of Qinghai needed to adhere to strict environmental and water protection requirements.  To do this, workers from SGCC Qinghai Electric Power Company didn’t build any roads or bridges, but used horse caravans known as “Electricity Caravans” to transport the material and facilities needed for the project.  This alternate mode for transporting materials also served to reduce edge effects compared with the normal practice of building a road or bridge.

Rehabilitation and Restoration: In situations where avoidance and minimization are not practical or feasible, companies may turn to a third strategy: rehabilitation and restoration.  With this strategy, a company attempts to rehabilitate degraded ecosystems or restore cleared ecosystems in areas that have previously been cleared, developed, or neglected.  In another example from China, The China National Petroleum Corporation (CNPC) pursued an ecological restoration effort as part of its Western Pipeline project.  As soon as the new pipes were laid down and buried, CNPC planted vegetation in an attempt to restore the original landscape.  In addition, CNPC adopted a higher design grade, increased the pipeline burial depth, enhanced the anti-corrosion grade of the pipes, and installed cut-off valves to prevent oil leakage in the event of any accidents.  Since the project was launched in 2004, CNPC has followed up with monitoring and remediation measures on an annual basis to ensure that the restoration effort is a success.

Biodiversity Offsets and Voluntary Compensatory Actions: If avoidance, minimization, and restoration strategies aren’t a viable option, then companies may turn to a fourth strategy: biodiversity offsets and voluntary compensatory actions.  The concept of a biodiversity offset is relatively simple. A company has a proposed project that will result in negative impacts to biodiversity at the target site.  To offset that loss, the company enters an agreement to protect biodiversity at another site.  The result is no net loss of biodiversity or, preferably, a net gain of biodiversity from the perspective of species composition, habitat structure, ecosystem function, and cultural values of biodiversity.  Biodiversity offsets differ from philanthropic donations and other compensatory actions by linking the offset to the biodiversity impacts of a specific project.  With voluntary compensatory actions, there is no formal link between the actual biodiversity impacts of the company’s development activities and the biodiversity gains from purchasing land for conservation.

Are these strategies “profitable conservation” strategies?

The short answer is, it depends.  From a business perspective, the business case is not always attractive.  In some industries, businesses are encouraged, and sometimes required, to implement these strategies in order to obtain permission to operate in certain areas.  The permission to operate in these areas can lead to huge financial gains.  In other cases, these approaches have fewer tangible benefits to the bottom line, but they can be effective risk-management strategies that are well received by regulators, customers, employees, and the local community.

From a biodiversity and wildlife perspective, anything that we can do to minimize impacts to the habitat they depend upon is a good thing.  However, the reality is that the cumulative impact of development projects is taking a toll on the health of wildlife populations throughout the world.

Parting words and coming attractions

Well there you have it!  I hope this post gives you a better idea about the topic of edge effects, why it matters from a biodiversity perspective, and the steps that businesses can take to minimize edge effects during planning and construction activities.

Next week, we’re off to The Netherlands, where we’ll be looking at oil and gas giant, Royal Dutch Shell, and it’s profitable conservation strategies that are good for business, biodiversity, and wildlife.

Thanks for reading!


State Grid Corporation of China’s Profitable Conservation Strategies for Biodiversity and Wildlife Conservation

June 11, 2018 By Mark Aspelin

As you can imagine, the State Grid Corporation of China (SGCC) is huge. After all, the company’s 1.72 million employees construct and operate power grids that supply energy to over 1.1 billion people, covering 88% of China. SGCC also owns and operates grids in outside of China, in countries such as the Philippines, Brazil, Portugal, Australia, and Italy. Not surprisingly, this makes SGCC the largest electric utility in the world, and places the company at #2 on the 2018 Fortune Global 500 list.

In reading through SGCC’s 2015 and 2016 Corporate Social Responsibility Reports (the 2017 CSR Report was published in February 2018 but is not available on the SGCC website) and “White Paper on Green Development”, it quickly becomes clear that SGCC’s primary focus from an environmental perspective is on Global Energy Interconnection (GEI), which includes the use of ultra-high-voltage (UHV) electricity transmission, smart grid technologies, and the conversion to clean energy. The reasons for this approach are both practical and strategic. China’s energy resources are located far from the major population centers. For example, most of China’s abundant coal resources are located in the northwest, and its hydropower resources are located in the west, but most of the demand is in eastern and southern China. Ultra-high-voltage electricity transmission enables SGCC to reduce transmission losses to an acceptable level as the electricity is delivered to where it’s needed.

UHV grids also enable SGCC to build new, cleaner, more-efficient power generation plants that are based on wind, solar, and nuclear energy, and then deliver that electricity across long distances to major population centers. And when SGCC says “global energy interconnection” they aren’t kidding. SGCC intends to connect large energy bases and distributed generation at the North Pole (wind) and the Equator (solar) and deliver the energy to customers across the world. As SGCC Chairman Liu Zhenya puts it, “Global energy interconnection can connect power grids in different continents with time zone and seasonal differences to solve energy and environmental problems that have been bothering human development for a long time, ensuring safe, clean and sustainable energy supply. Life will be better as the world is turning into a bright, peaceful and harmonious global village with sufficient energy, green land and blue sky.”

With the help of Global Energy Interconnection, SGCC anticipates that global clean electricity generation will account for 80% of total primary energy by 2050, reaching 66,000TWh, which represents a nearly ten-fold increase from 2010.  This will replace 24 billion tons of standard coal every year, reducing CO2 emissions by 67 billion tons and SO2 by 580 million tons.

When it comes to biodiversity and wildlife conservation,  SGCC focuses on the link between climate change and biodiversity with the following quote from the Intergovernmental Panel on Climate Change, along with a photo of a polar bear: “If global temperature rises by 1.5 ~ 2.5 ℃, 20% ~ 30% of the assessed species could face extinction. If the temperature rises by over 3.5 ℃, 40% ~ 70% of the assessed species may become extinct. (“IPCC Second Assessment”, 1995).”  SGCC also points out that a large number of species are facing extinction risk due to the slow rise of sea levels that can be attributed to the receding and melting of glaciers and permafrost.

Let’s take a quick tour of the SGCC’s efforts to address the following four major threats to biodiversity: habitat destruction, invasive species, pollution, and overharvesting.  Even though climate change poses a major threat to habitats, I generally put corporate climate change activities under the Pollution section, since the actions that companies take usually come in the form of pollution prevention initiatives.

Habitat Destruction

Reduce Land Use: SGCC has a goal to reduce land use by 10% and to reduce construction areas by 20%. To accomplish this, SGCC uses several different strategies, which are illustrated by the following success stories.

  • In North China Grid Company’s ”11th Five-year Plan”, 50,225,100 square meters of land has been spared by applying compact lines and multi-circuits on the same tower, 533,600 square meters of land were saved by utilizing GIS and HGIS, and 3335 square meters of land was saved by promoting large capacity transformer technology.
  • SGCC implemented an “Electricity Caravan” concept to minimize environmental impacts in a fragile plateau environment in the area of Sanjiangyuan National Nature Reserve (pictured below), known as “the water tower of China”. This project between Golog and the main grid of Qinghai needed to adhere to strict environmental and water protection requirements. To do this, workers from SGCC Qinghai Electric Power Company didn’t build any roads or bridges, but used horse caravans known as “Electricity Caravan” to transport the material and facilities needed for the project.
Sanjiangyuan National Nature Reserve

  • The Fujian Baihua-Bili 220kV Transmission Project includes 2-circuit 220kV and 4-circuit 110kV lines. “The project performs remarkably with less land occupation and less consumption of materials and resources, reducing the crossover of 25 civil buildings, 114,724 square meters of land occupation, over 120m of corridor width, and 13% of steel consumption, on the other hand, increasing the unit corridor transmission capacity by 235%, thus bringing down the total investment of RMB 5.32 million.”
  • SGCC estimates that it reduces the amount of land needed by 25% – 50% by using EHV AC lines rather than transporting coal by railroad and sea.

Charitable Giving and Volunteer Efforts: In 2015, SGCC gave 128 Million RMB (~$19 Million US Dollars) in public donations, provided 15 Million RMB (~2.2 Million US Dollars) via the State Grid Foundation for Public Welfare, and staff provided 2 million hours of volunteer work to support various efforts, such as poverty alleviation and scholarship funds. In addition, 2.8 million employees have participated in 1,365 tree planting activities, resulting in the planting of 677,811 trees over a period of 5 years.

Invasive Species

There is no mention of any efforts to address invasive species in SGCC’s various reports and website.


Climate Change and Renewable Energy: The primary effort that SGCC is focused on from a biodiversity and wildlife conservation perspective is to reduce its contribution to climate change through the development of a strong and smart grid.  SGCC is actively pursuing the use of clean energy alternatives to fossil fuels, such as wind, hydropower, solar, and nuclear energy. In addition SGCC has actively supported the development of electric automobiles by building 1,537 charging stations, 29,600 charging piles, and a quick charge network that covers 81 cities and 11,000 kilometers of highways. In rural parts of China, SGCC is also partners with the government to implement projects that substitute electricity for coal, oil, and firewood.

Pollution Control: SGCC’s primary pollution control efforts come through its reduction of greenhouse gases. For example, one of its pollution control strategies is focused on recollecting sulfur hexafluoride (SF6). SGCC established SF6 gas recollection and treatment center at a provincial level to strengthen the regulation on the recollection, treatment, and recycling of air, which contributes to the reduction in the emission of greenhouse gases. In 2015, these provincial centers recollected and treated 47.1 tons of SF6 gas, which is equivalent to a reduction of 1.126 million tons of CO2 emissions.

Training: SGCC organizes a variety of environmental protection training activities. “In 2015, the company organized 112 training courses on environmental protection with 4,550 participants, and organized more than 180 activities concerning the development of grid, energy conservation, and emission reduction.”


Overharvesting and overhunting threats to biodiversity are not addressed in SGCC’s website or reports.

Profitable Conservation

The CSRs and White Paper do not provide much in the way of return on investment data for the company’s environmental efforts. Nearly all of the RMB figures in the two reports specify how much the company has invested, rather than return on investment. For example, SGCC reports the following environmental investments:

  • Total investment in environmental protection: RMB 5.72 billion
  • Investment in environmental protection for construction projects: RMB 5.32 billion
  • Investment in environmental protection during grid operation: RMB 230 million
  • Investment in environmental research and special areas: RMB 170 million
  • Investment in environmental protection management: RMB 120 million
  • Investment in environmental protection governance: RMB 93 million
  • Cost of environmental protection facilities’ operation and maintenance: RMB 15 million

We can compare SGCC’s clean energy capacity figures with the company’s overall revenues, as summarized below, to give us a rough idea of what priorities SGCC is focused on in the world of clean energy, with the assumption that these efforts must be profitable in some way or else SGCC would not pursue these options.

Energy Source (Integrated Capacity in GW)

  • Nuclear Power: 6.4 GW in 2011, 17.02 GW in 2015
  • Hydropower: 156.17 GW in 2011, 207.82 GW in 2015
  • Solar (Photovoltaic) Power: 2,320 GW in 2011, 44,465 GW in 2015
  • Wind Power: 35,190 GW in 2011, 116,640 GW in 2015

Total Revenues (Billion RMB)

  • Total Revenues 2011: 1675.4
  • Total Revenues 2015: 2075.0

SGCC does provide some return on investment data for the following efforts:

  • Jinyun, Zhejiang In Jianchuan County, Xinjian Town, implement pilot projects of distributed PV (solar) generation for 60 low-income families. These projects earned over 2,000 RMB per household every year, and most of the farmers were able to get out of poverty.
  • The Fujian Baihua – Bili 220kV Transmission Project includes 2-circuit 220 kV and 4-circuit 110kV lines. The project performs remarkably with less land occupation and less consumption of materials and resources, reducing the crossover of 25 civil buildings, 114,724 square meters of land occupation, over 120m of corridor width, and 13% of steel consumption, on the other hand, increasing the unit corridor transmission capacity by 235%, thus bringing down the total investment of RMB 5.32 million.

Biodiversity & Wildlife Conservation Performance Assessment

SGCC has adopted climate change as its key issue of concern.  This shouldn’t come as a big surprise given that SGCC is in the electric power industry, coupled with the fact that China has an abundance of dirty coal and a shortage of electricity.  China needs to look at alternative energy options in order to make progress on its commitment to achieve a 40-45% reduction in CO2 emissions per unit of gross domestic product from by 2020, using the year 2005 as a baseline.  To its credit, SGCC is aggressively pursuing alternative energy and smart grid technologies to help achieve that objective.

I was also happy to see SGCC’s goal to reduce land use by 10% and to reduce construction areas by 20%.  However, SGCC’s CSRs and White Paper are relatively weak when it comes to discussing the company’s direct impact on biodiversity and wildlife. With 889,900 km of transmission lines in China alone, SGCC’s operations certainly have a significant, direct impact on biodiversity and wildlife.  As the U.S. Fish & Wildlife Service points out on its website:

“Transmission lines and other linear developments like pipelines, roads and trails, can increase human access into natural areas, displace wildlife from their habitat, act as barriers to wildlife movement and affect migration routes. They have the potential to impact sensitive ecosystems such as wetlands, impact high quality fishery resources when waterways are crossed, and create pathways for the spread of invasive species.  Operation and maintenance of transmission line right-of-ways (ROWs) may also result in environmental impacts. ROW maintenance often involves the chemical or mechanical control of vegetation that can contribute to the loss of native plant species diversity.  Cleared ROWs may be a continuous source of sedimentation into waterways.  In addition to these potential impacts, transmission lines can pose collision and electrocution risks to migratory birds.”  

In addition to transmission line corridors, the utilities industry also has the potential for significant biodiversity and wildlife impacts through extensive water use and the siting of new infrastructure.  Any company with such a large ecological footprint and direct impact on wildlife should have more to say on the topics of biodiversity and wildlife conservation.  This is an opportunity for SGCC to consider in future CSRs.

However, based on SGCC’s stakeholder and customer analyses, where the company plots environmental topics on a graph with a value creation dimension (relevance, importance, and feasibility) on the x axis and a social concern dimension on the y axis, biodiversity is not even on the list of contenders.  The top environmental issues that were identified include governing air pollution, combatting climate change, constructing electric vehicle (EV) charging facilities, and improving energy efficiency.  In addition, a major reporting standard, the Sustainability Accounting Standards Board (SASB), considers biodiversity to be “not likely a material issue” for companies in the utilities industry, although SGCC uses the GRI reporting standard for its CSR.  These factors may explain why SGCC chooses not to cover biodiversity and wildlife conservation in more detail in its various communications.

SGCC was the first state-owned enterprise in China to issue a Corporate Social Responsibility Report (in March of 2006), and I applaud SGCC’s efforts to share its environmental performance in its CSRs and White Paper.  I hope to read more about SGCC’s progress in its efforts to protect wildlife and biodiversity in the years to come.

Coming Attractions

For our next company, we won’t have to journey far.  We’re just headed down the street in Beijing to learn about Sinopec, #3 on the list of the Global 500.  We’ll explore what Sinopec is doing in the areas of biodiversity and wildlife conservation.  Zàijiàn!

Thanks for reading!