A century after the Appalachian Trail was proposed, millions hike it every year seeking ‘the breath of a real life’

McAfee Knob in Virginia’s Blue Ridge Mountains, one of the Appalachian Trail’s most scenic vistas.
Ben Townsend/Flickr, CC BY

Charles C. Chester, Brandeis UniversityThe Appalachian Trail, North America’s most famous hiking route, stretches over 2,189 mountainous miles (3,520 kilometers) from Georgia to Maine. In any given year, some 3 million people hike on it, including more than 3,000 “thru-hikers” who go the entire distance, either in one stretch or in segments over multiple years.

The AT, as it’s widely known, is a national icon on a par with conservation touchstones like the Grand Canyon, Yellowstone’s Old Faithful geyser and the Florida Everglades. It symbolizes opportunity – the chance to set out on a life-altering experience in the great outdoors, or at least a pleasant walk in the woods.

Benton MacKaye, the classically trained forester who proposed creating the AT in 1921, saw it as a space where visitors could escape the stresses and rigors of modern industrial life. He also believed it could be a foundation for sound land-use patterns, with each section managed and cared for by local volunteers. MacKaye was a highly original thinker who called for protecting land on a continent-spanning scale and thought about how land use patterns could influence work and social relationships.

Halfway there, more or less: a trailhead in Harpers Ferry, West Virginia.
Michel Curi/Flickr, CC BY

My research focuses on how people work together to promote large landscape conservation and to protect connectivity – physically linking patches of habitat, on land or at sea, so that animals and plants can move between them. MacKaye’s conception of the AT represents an early example of such comprehensive approaches to conservation.

An escape from industrial life

One hundred years ago, MacKaye laid out his vision for the AT in an article for the Journal of the American Institute of Architects. At that time, progressive thinkers were conceptualizing and promoting the idea of regional planning at many different scales.

Had MacKaye focused solely on a physical trail, the editors probably would have rejected his manuscript. But MacKaye envisioned the AT as a connecting cord that would run through and define a natural and rural region. In his view, maintaining the undeveloped character of the land would only become more essential in the face of an encroaching East Coast metropolis. And because it lay in the eastern U.S., the trail would “serve as the breath of a real life for the toilers in the bee-hive cities along the Atlantic seaboard and beyond,” he wrote.

By 1925 MacKaye organized an Appalachian Trail Conference to build the footpath, which was completed in 1937. The first thru-hiker, a World War II veteran named Earl Shaffer, completed the full journey in 1948. Over the following decades, most of the practical work on the AT focused on tying together the thread of the trail itself – a challenging mission of acquiring access rights to myriad public and private lands.

Clips from an AT thru-hike, moving from south to north.

Maintaining the landscape around the AT in perpetuity is a bigger challenge. And climate change is making that issue more urgent, for the AT isn’t just a footpath for humans. It also provides two ways for plants and animals to shift their ranges in a changing world.

First, the trail offers a chance for wildlife and plants to move northward to cooler habitats on a warming planet. Second, species can also move up mountains to avoid warmer temperatures – and any thru-hiker has the blisters to prove that the AT has plenty of mountains.

More than a footpath

Beginning with MacKaye, many people over the past century have aspired to frame the AT as a platform for conservation at a regional scale – that is, extending far beyond the narrow trail corridor, which averages about 1,000 feet (300 meters) wide, or less than a quarter of a mile. One impetus is to provide a natural experience for hikers. Who wants to go exploring through exurban sprawl? Protecting land around the trail also expands spaces for plants and animals.

One of the best-known examples of large landscape approaches is the Yellowstone to Yukon Conservation Initiative, often referred to as Y2Y (I am the current chair of the Y2Y Council). Since the mid-1990s, this venture has striven to conserve habitat and rural working lands across a region that stretches some 2,000 miles (3,220 kilometers) north from the Greater Yellowstone region in Wyoming, Montana and Idaho to Canada’s Yukon Territory.

As the Y2Y experience has shown, conserving large landscapes around the AT will not be easy or straightforward – but it is possible. MacKaye worried about urban and suburban encroachment – a threat that has only grown more severe over the past hundred years. “Pinch points” include the mid-Atlantic portion of the AT, but development threats are present all along the trail.

Conservation advocates have identified key spots along the AT where land around the trail could be protected from development to support wildlife by preserving it as open space. They include highlands in northern New Jersey and southern New York; forests and wetlands in Vermont and New Hampshire; and Maine’s North Woods.

Land trusts and conservation organizations from Georgia to Maine are working to protect wild lands along the length of the AT and increasingly are coordinating their efforts through the Appalachian Trail Landscape Partnership. This initiative includes more than 100 partners, led by the Appalachian Trail Conservancy and the U.S. National Park Service, which has managed the AT since the passage of the 1968 National Scenic Trails Act.

Footpath and barrier

Benton MacKaye hoped that the AT would be a symbolic and literal pathway toward solving social problems. His initial vision for the trail included community camps, covering up to 100 acres, that would grow out of trail shelters into small settlements where people could live year-round and pursue “nonindustrial” activities such as study and recuperation. Eventually, he envisioned more permanent camps that would offer the opportunity to move from cities back to the country and work cooperatively on the land, raising food and harvesting timber.

“The camp community … is in essence a retreat from profit. Cooperation replaces antagonism, trust replaces suspicion, emulation replaces competition,” MacKaye wrote.

MacKaye’s grand hopes may have been idealistic, but fulfilling the AT’s potential for large landscape conservation in some of the most populated regions of North America is still a worthy goal. As MacKaye presciently concluded in his 1921 article, “This trail could be made to be, in a very literal sense, a battle line against fire and flood – and even against disease.” A century later, I believe the time has come for MacKaye’s vision of the trail to flourish as a mutually supportive endeavor among people and nature in a changing world.

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Charles C. Chester, Lecturer in Environmental Studies, Brandeis University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Monks Wood Wilderness: 60 years ago, scientists let a farm field rewild – here’s what happened

UK Centre for Ecology & Hydrology, Author provided

Richard K Broughton, University of OxfordIn the archive of the UK Centre for Ecology & Hydrology there is a typed note from the 1960s that planted the seed of an idea.

Written by Kenneth Mellanby, director of the Monks Wood Experimental Station, a former research centre in Cambridgeshire, UK, the note describes a four-hectare arable field that lies next to the station and the ancient woodland of the Monks Wood National Nature Reserve. After harvesting a final barley crop, the field was ploughed and then abandoned in 1961.

The note reads:

It might be interesting to watch what happens to this area if man does not interfere. Will it become a wood again, how long will it take, which species will be in it?

So began the Monks Wood Wilderness experiment, which is now 60 years old. A rewilding study before the term existed, it shows how allowing land to naturally regenerate can expand native woodland and help tackle climate change and biodiversity loss.

The Monks Wood Wilderness field (outlined in red) shortly after abandonment in the early 1960s.
UK Centre for Ecology & Hydrology, Author provided

How new woodland generates itself

A shrubland of thorn thickets emerged after the first ten to 15 years. Dominated by bramble and hawthorn, its seeds were dropped by thrushes and other berry-eating birds. This thicket protected seedlings of wind-blown common ash and field maple, but especially English oak, whose acorns were planted by Eurasian jays (and maybe grey squirrels too) as forgotten food caches. It’s thought that jays were particularly busy in the Monks Wood Wilderness, as 52% of the trees are oaks.

Jays habitually collect and cache acorns in autumn. Forgotten caches germinate into oak seedlings.
UK Centre for Ecology & Hydrology, Author provided

The intermediate shrubland stage was a suntrap of blossom and wildflowers. Rabbits, brown hares, muntjac deer and roe deer were all common, but the protective thicket meant there was no need for fencing to prevent them eating the emerging trees. Those trees eventually rose up and closed their canopy above the thicket, which became the woodland understorey.

The result is a structurally complex woodland with multiple layers of tree and shrub vegetation, and accumulating deadwood as the habitat ages. This complexity offers niches for a wide variety of woodland wildlife, from fungi and invertebrates in the dead logs and branches, to song thrushes, garden warblers and nuthatches which nest in the ground layer, understorey and tree canopy.

The Monks Wood Wilderness in 2021, after 60 years of natural regeneration.
UK Centre for Ecology & Hydrology, Author provided

The Monks Wood experiment benefited from the field lying close to an ancient woodland, which meant an ample supply of seeds and agents for their dispersal – jays, rodents, and the wind. Such rapid colonisation of the land would be unlikely in more remote places, or where deer are superabundant.

But there are many woods in the UK that could expand by allowing adjacent fields to return to nature. This would eventually add up to a significant increase in total woodland cover.

The Monks Wood Wilderness (outlined in red) in 2014.
UK Centre for Ecology & Hydrology, Author provided

Tree planting or natural regeneration?

The UK is one of the least forested places in Europe, with just 13% forest cover compared to an average of 38% across the EU. Only half of the UK’s forest is native woodland, which sustains a wide variety of indigenous species. The rest is dominated by non-native conifer plantations grown for timber.

This situation is gradually changing. The UK government aims to create 30,000 hectares of new woodland each year until 2025, providing new habitat for wildlife and helping reach net zero emissions, as woodland stores more carbon than any other habitat except peatlands.

With the climate and biodiversity crises getting worse each day, there’s an urgent need to expand woodland fast. But how? Tree planting is the usual approach, but it’s costly. Saplings also have to be grown, transported, planted and protected with fencing and plastic tubes – that’s a lot of carbon emissions and potential plastic pollution, as tubes break down into the soil.

What about doing virtually nothing instead? Natural regeneration involves creating woodlands by allowing trees and shrubs to plant themselves under natural processes. It’s free and involves no plastic or nursery-grown saplings, which can introduce diseases. The result is woodland that’s well adapted to local conditions.

Oak seedlings were early pioneers in the regeneration of the woodland.
UK Centre for Ecology & Hydrology, Author provided

Allowing the land to naturally regenerate sounds exciting, but planners and ecologists need to know where this approach is likely to work best. How abandoned land turns into woodland is rarely documented, as it usually happens where people have walked away.

The Monks Wood Wilderness fills in this gap in our knowledge as an example of planned natural regeneration that has been monitored over decades, with a second two-hectare field (named the New Wilderness) added in 1996 to expand the experiment.

Shrubland in the New Wilderness field after 25 years, with hawthorns blossoming.
UK Centre for Ecology & Hydrology, Author provided

Since the 1990s, the two Wildernesses have been regularly surveyed by scientists counting and measuring trees on foot and tracking tree cover from planes and drones. These surveys documented the development of woodland over 60 years in our recently published study, revealing the patterns of habitat regeneration.

We can now finally answer Mellanby’s 60-year old questions. Within 40 to 50 years, the ploughed field became a closed canopy woodland with almost 400 trees per hectare. And as the canopy grows taller, more plant and animal species are arriving, such as marsh tits and purple hairstreak butterflies – mature woodland specialists that have made a home here as the habitat gradually converges with the ancient woodland nearby.

The Wilderness experiment shows what’s possible when nature is allowed to create rich, native woodland for free. I think Mellanby would be pleased with how it all turned out.

Richard K Broughton, Ecologist and Ornithologist at UK Centre for Ecology & Hydrology and Senior Research Associate in Zoology, University of Oxford

This article is republished from The Conversation under a Creative Commons license. Read the original article.

‘How high above sea level am I?’ If you’ve googled this, you’re likely asking the wrong question — an expert explains

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Shayne McGregor, Monash University; Nerilie Abram, Australian National University, and Ruth Reef, Monash UniversityThe latest report from the United Nations Intergovernmental Panel on Climate Change is confronting. It finds global mean sea levels rose by about 20 centimetres between 1901 and 2018. In fact, sea levels have risen faster over the last hundred years than any time in the last 3,000 years.

This acceleration is expected to continue. A further 15-25cm of sea level rise is expected by 2050, with little sensitivity to greenhouse gas emissions between now and then. Beyond 2050, however, the amount of sea level rise will largely depend on our future emissions.

In a low-emissions scenario, we can expect sea levels to rise to about 38cm above the 1995–2014 average by the year 2100. In a high-emissions scenario this is expected to more than double to 77cm.

In either case, who will feel the effects of sea level rise? And how much does your location’s height above sea level really matter? It’s a question a lot of you have been googling since the report’s release. But the answer isn’t straightforward.

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Read more:
This is the most sobering report card yet on climate change and Earth’s future. Here’s what you need to know

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Sea level rise isn’t uniform

Since satellites began measuring sea surface height almost three decades ago we have learned sea level rise is not uniform across the globe.

The map on the left in this video shows daily sea level variations since 1993, while the curve on the right shows the month-by-month global mean sea level.

In fact, sea levels can vary quite substantially on a year-to-year and decade-to-decade basis. However, we know much of this regional variability is driven by surface wind changes — and will typically decrease over long periods.

So while the IPCC report’s projections are for global mean sea level for the year 2100, most coastal locations will experience a sea level rise within 20% of the projections (which are subject to change beyond 2050 depending on global emissions).

Flood zones and drainage

Elevation above the high tide is an important factor in determining how at risk a particular location is of experiencing flooding due to sea level rise.

In low elevation coastal zones, physical distance to the coast and certain topographic features in the area such as sand dunes, wetlands and human built structures like levies and flood walls can act as a buffer to sea level rise.

That said, current and projected sea level rise may still pose a significant risk to regions with these buffers, as there are many ways by which sea level rise can lead to flooding.

For instance, as sea levels rise water from the sea can inundate storm water drainage systems and end up flooding inland regions with elevations below (or which will eventually be below) sea level. This is because drainage largely depends on gravity, and some storm water systems don’t have flood gates to stop water entering from the ocean.

Here we see Bobbin Head in NSW flood during a king tide. This problem will become more pronounced as sea levels rise and will require clever engineering solutions, such as drainage pumps to push water back out to sea.

There are also cases where man-made features intended to help protect people from sea level impacts can be breached, resulting in flooding. One prominent example was the New Orleans flooding that occurred during Hurricane Katrina, when the man-made flood levee system suffered many failures

The tidal range around Australia varies from less than 1m in some parts such as southwest Australia, to more than 8m in other parts such as the northwest.

The tidal range in an area determines how quickly flooding impacts will increase as sea levels rise. If two regions have the same elevation, as the high tide rises past the regions’ elevation, the region with a smaller tidal range will likely struggle with more flooding and for longer than the region with a larger tidal range.

Beach erosion increases risk

Yet all of the above hasn’t considered the fact our beaches are naturally mobile systems which respond to change. This is why the relationship between an assets elevation above the high tide mark and risk of flooding is less straightforward at low elevation coastal zones — where 11% of Australia’s population lives.

When sea levels rise, the shape of the coastline changes with it and can move inland to a great extent. If sea levels rise by 1m, the coast can erode inland by 1km or more. This can potentially create risk for properties even if they are currently above the height of the projected sea level rise.

Australia has many retreating coastlines, often forming striking erosional landforms such as The Great Ocean Road region.

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Read more:
The world may lose half its sandy beaches by 2100. It’s not too late to save most of them

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However, the response of the coastline can also be moderated by natural and human factors. In some regions, coastal elevation is actually increasing due to sediment being deposited, or tectonic uplift raising the coast as fast (or even faster) than rising sea levels.

In Australia, this is especially pronounced in estuaries with a riverine supply of sediments and where vegetation such as mangroves, saltmarshes and dune vegetation help collect sediment in their root systems.

We know sea level rise is with us for the long haul. And it’s now inevitable we will have to adapt to changes along our coasts. We’re already using a number of approaches to counteract projected sea level rise in Australia, including:

• sand renourishment of beaches
• the formation of more seagrass, saltmarsh and mangrove habitats
• construction of seawalls and other hard coastal protection measures.

But it’s important to note we still have a choice for how much and how quickly sea levels will rise beyond 2050. So perhaps, instead of googling your current elevation, a more pragmatic approach would be to think of what you can do to help protect your own coasts and reduce your carbon footprint.

Shayne McGregor, Associate professor, Monash University; Nerilie Abram, Chief Investigator for the ARC Centre of Excellence for Climate Extremes; Deputy Director for the Australian Centre for Excellence in Antarctic Science, Australian National University, and Ruth Reef, Associate Professor, School of Earth Atmosphere and Environment, Monash University

This article is republished from The Conversation under a Creative Commons license. Read the original article.