Time spent in the natural world benefits human health

Below Article appeared originally in The American Scientist.
July-August 2011Volume 99, Number 4 Page: 301

A Walk in the Woods » American Scientist.

A Walk in the Woods

Evidence builds that time spent in the natural world benefits human health

Anna Lena Phillips

For the month of April, I decided to visit the Haw River, which flows near where I live, every day. I wouldn’t hold myself strictly to this, but I would try, and I would observe—not impartially, of course, but closely—how I felt. Some days I took leisurely walks with friends, leaning over the railing of the pedestrian bridge to watch the river, high from recent rains, and to smell the distinctive, muddy smell of the water mingled with that of the banks overrun with invasive honeysuckle. On others, coming home late at night, I drove straight down to the bridge and walked out to stare down at the dark water, a move that felt a bit like the natural-world equivalent of visiting a drive-through restaurant.

I did this because I hadn’t been spending much time at the river, even though it’s only a short walk from home, and even though I like doing it. The results of my informal experiment? I did, in fact, feel better—calmer, more relaxed, clearer-headed. I suspect that many people have similar feelings about the effects of spending time in the wilder places near where they live. Perhaps that’s why Richard Louv’s 2005 book Last Child in the Woods, which explores the relation between the natural world and children’s development, became a bestseller in the United States.

2011-07SciObsPhillipsFA.jpgClick to Enlarge ImageBut to know empirically that these experiences are beneficial—and to know exactly how they might help us—requires more than personal experience. A growing and varied body of research attempts to quantify how and why spending time in the natural world might have beneficial effects on humans’ physical and psychological health. One of the first and most well-known studies, published in Science by Richard S. Ulrich in 1984, found that patients recovering from surgery in rooms with a window facing a natural setting had shorter hospital stays and took less pain medicine than did patients whose window faced a brick wall. Since then, researchers have asked whether the presence of trees influences people’s sense of safety in inner-city neighborhoods; explored how gardening might improve quality of life for people with disabilities; and used physiolgical measures to test for restorative effects of natural environments. If some of these studies seem too specific to be useful in answering the broader question, their results in sum suggest that time spent in nature improves human health. The more difficult questions are how, and in what ways, these effects arise. These questions are not the kind that can be answered by a single, groundbreaking paper; rather, like so many of the subtle and complex problems science explores, the evidence is being deposited, small study by small study, like layers of sediment on a river bed.

One such body of work is accumulating in Japan, where researchers are investigating the physiological effects of shinrin-yoku—“forest bathing,” or, to put it plainly, taking walks in the woods. Qing Li, a professor in the Department of Hygiene and Public Health at Nippon Medical School, Tokyo, has been involved with several such studies. He and his colleagues recently measured specific physiological markers before and after study subjects took walks in a forest and in an urban control environment. The study’s sample size is small—16 male subjects—and the timescale short—effects were measured after one day trip to the forest and one to the city—but the results suggest that the forest trip had positive effects on health. Subjects’ blood pressure measured in the forest was significantly lower when compared to measurements taken in the city. Levels of the stress hormone noradrenaline, measured in urine, were also significantly lower after the forest walk than after the urban walk. And blood levels of the adrenal hormone dehydroepiandrosterone sulfate (DHEA-S) and of adiponectin, a hormone secreted by fat tissue, were higher after the forest walk but not the urban walk. The authors note that DHEA-S may contribute to heart health, among other benefits, and that lower levels of adiponectin are associated with obesity and type 2 diabetes.

Li and his coauthors, whose study appeared in the European Journal of Applied Physiology in March, speculate that the forest trip’s effects on blood pressure may be related to phytoncides, volatile organic compounds (VOCs) that plants produce and release as protection from fungi and bacteria. In a separate study for which Li was also lead author, researchers unsurprisingly found higher concentrations of several phytoncides in a forest than in an urban area of Tokyo.

Another recent study, by Juyoung Lee, a researcher at the Center for Environment, Health and Field Sciences at Chiba University, Japan, and others, offers similar results. In this three-day field experiment, 12 young male subjects visited forest and urban environments. The study, published in February in Public Health, found that in the forest, subjects’ parasympathetic nervous-system activity was heightened and their sympathetic nervous-system activity suppressed. Pulse rates were lower, as were salivary levels of the adrenal hormone cortisol, which is associated with stress. Participants reported that their positive feelings increased, and negative feelings decreased, in the forest. Blood-pressure measurements, however, did not differ significantly between the forest and urban locations. The authors also measured phytoncide levels in the forest study area and found 10 different compounds, ranging in concentration from 0.3 micrograms per cubic meter to 1,336 micrograms per cubic meter.

In support of the idea that phytoncides may be responsible for some of the health effects seen in Li’s study, he and his coauthors cite a 2003 paper that found that inhalation of cedar-wood oil lowered blood pressure. A review article of forest-bathing studies, published in Environmental Health and Preventive Medicine in 2009 by Yuko Tsunetsugu and others, notes several laboratory studies that tested human responses to inhalation of plant VOCs. The results included such positive effects as lowered blood pressure and improved task performance. But to find a correlation between the mixture of phytoncides in forest air and physiological changes in humans would require experiments of more complex design. So although the idea that the very scent of the forest might improve health is appealing, determining whether it’s true and the extent of any effects will need more study.

This is just one of many avenues of inquiry that forest-bathing research opens. Can the physiological effects of studies like Li’s be replicated in larger studies, and in women and children? Do effects differ across gender and age? Do forests in varied bioregions, with different microclimates and compositions of tree species, vary in their effects on health? Do people who have grown up in one region experience different health effects in forests in their home bioregion than in other forests?

Policy questions abound as well. Carol Colfer, a cultural anthropologist and senior associate with the Center for International Forestry Research in Bogor, Indonesia, studies human use of forests in developing countries. “I suppose the logical result would be developing more or at least maintaining existing parks in cities, and expanding protected areas—but with much more serious attention to the human rights of people living in these areas,” she says of Li’s study. “Even better would be encouraging in situ conservation on people’s own lands.” Li is interested in exploring how his results could be used in medicine. “I am planning to develop forest bathing to be a preventive measure for some diseases such as depression, hypertension and cancers,” he says.

 

What’s clear is that trying to quantify a seemingly intuitive claim—humans benefit from spending time in the natural world—is turning up more complex answers, and more resulting questions, than a fir tree has needles. If policymakers take note of this work as it emerges, they might be better equipped to improve public health. For my part, I’ve extended my efforts to visit the river each day into the month of May. The weather’s better for swimming now, and the air smells as good as ever.

Eastern Screech Owls -an Album

In early June momma Screech brought two little fluffy Owlets around to show.  They were barely flying – more like bombing around … and they were very needy with their calls for food!    Here is mom below, with one of her fledgling chicks.  I have a long relationship with the screech owls around our neighborhood and every year we get to see them as they perch and hunt in and around our half acre for insects here in Lehigh.  
The tree below is over our Labyrinth and I was sitting under it when she brought them by.  Yes, I try to always have a camera on hand in the Backyard Universe just in case!  
Mom and Owlet

Mom and Owlet

Above and below a fluffly barely fledgling Screech closer up, sitting in the tree above with mom.  Mom had left them up in the tree overhead while she went off to hunt in daylight.  The only issue is, during daylight hours they can be attacked by other birds that find them and this was an open area.  I helped mom out and kept the mocking birds and jays away while the little ones sat up in the tree calling for mom to bring them yummy beetles from nearby backyards.  They were not that far from their nest in a clump of Sabal Palms behind our lot.  (We let our native yard grow tall and wild in the back for cover and hunting areas for the little ones.)  
Fluffly chick

Fluffly chick

In the below images they are much older but still sporting some pin feathers.  The don’t need mom to watch after or protect them from attacking birds.  They know to hide in the shadows during daylight hours until nightfall.

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Hiding in among the Bombax tree leaves… a wide eyed fledgling Screech.  300mm Nikon lens

Other Fledgling

I am outside, after dinner looking for the screeches.  Sometimes after a rain I hear them or late at night calling with their soft whinny call…  Eventually they will move out to other areas of the neighborhood to hunt over the Summer.  I hope they are greeted with as much awe, enjoyment and safe haven as they are met with here on the half acre.  Owls like this hunt insects, small bats, mice and snakes.  In yards sprayed with pesticides, they may suffer through their food sources that are impacted by the pesticide applications.  
I have found that when our rodent or snake numbers go up here at the Backyard Universe that we often see an influx of hawks and owls to feed on them.  It’s an intricate, connected age old cycle that will balance itself  out if we allow it to and don’t interrupt it via artificial and deadly means.  If you would like to build Screech Owl Nest Boxes for your yard, go to this link  in my prior article and read down it for the link to the nesting box instructions.
 

Screech Owls New Diggs, up in the Bombax Tree.

Screech Owls New Diggs

The Backyard Universe is truly a hub of activity lately…   every evening the mockingbirds are giving the little Screech Owls a difficult time when they make their appearance known.  You can’t miss the disturbed calls of the mockingbirds and the hisses of the Screech owls.  It was at this latest activity that I decided to read online about Screech Owl Boxes.  They had a nest last year in an old palm snag however that snag fell over this year.  After doing some research I ran across a website for the Treasure Coast Wildlife Center located in Palm City Florida.  They actually had a .PDF file with information about Screech owls AND how to build nesting boxes for them.  It just happens that the boxes for the Screech Owls can also be used by the American Kestrel.  Click here for the Download .PDF link to make your own Screech Owl Nesting Box.

We placed our box up onto a Bombax  (African Floss) Tree, part of a stand of them that is along the back of our half acre.  Now we watch and wait to see if the box is noticed and who takes interest!  The box took only a couple hours to make and cost us $13.00 in pine.  It will weather over time.  Please be sure to follow the directions of the .PDF, don’t paint the box.  Now when I go outside I have yet another possible source of activity to keep an eye on.   We have raised other clusters of Screech Owls here, watched them grown up…  I hope you will consider placing a box in your neighborhood backyard.   A big thank you to the Treasure Coast Wildlife Center for making the easy to follow directions available.  Check out their website!     AND be sure to visit my new Photo Blog called Metta Nature Photography  Click on the images there for full page views of everything else *outside* of my  BackyardUniverse coverage.    

Eastern Screech Owl

Image of an Eastern Screech Owl sitting on a stump in the BackyardUniverse.   

Something Fishy in aBackyard Universe this morning..

I had just mentioned to someone last night, “Pay attention to birds because THEY will tell you what’s going on in the neighborhood or on the trail”   And it’s true, IF you do choose listen to Nature, she will share important things with you.  Like this morning as I was walking out onto the lanai to let the Chihuahuas out I heard this very distinctive call to my left…  

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The neighborhood Osprey was a lot closer to me than the last time I blogged about him – when he was 200′ distant in another neighbors yard…  So I quietly stood and fired off images until the Mockingbird chased him away.  That was a very narrow window I had to enjoy his presence in and I’m grateful for it!  I do hope someone else had the enjoyment of watching him with his meal, that everyone was not glued to the TV and missed an opportunity.

Seeing an Osprey close in like this is a rarity for me.  I’m not near a large body of water such as a beach or lake, so the Ospreys I see occasionally here have travelled to and from larger water sources, or perhaps fished the deep canal that runs along behind (to the East of)  Lehigh Acres Middle School, which isn’t far from me.  I do hope YOU had a chance to get outside this weekend and soak up some wonderful Vitamin N – the Nature Vitamin, and I hope you enjoy the photos.    

the Rearview Spider

There is a Spider that travels with me, she lives in the back of my Saturn’s rear view mirror and builds her web outside of it to trap insects in.

She leads the fast life, going around town with me to meetings, classes and through drive throughs. It was during my trip through the Starbucks drive through that she surfaced again. So I parked to get a photo of her to share.

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February brought the Ladies Tresses..

a chill February found me exploring a lonely trail in search of flowers and their attendant butterflies…  Possibly a bear if I could see one.  It was after all why I had picked an early morning and this particular trail that skirted a vast South West Florida marsh   As I rounded an area looking down as I hiked I came across a small grouping, just a very few plants, of Nodding Ladies Tresses  (Spiranthes odorata) Orchids.  I had never seen these in my travels so it was pretty exciting!   Nodding Ladies Tresses grow low and are rather  small and they tend to blend in with the rest of, well, everything in the grasses.  The blooms only last about a week or two so I was very lucky to come across them.  Nodding Ladies Tresses are a ground orchid with just a few leaves and this wonderful flower spike that comes up about a foot.  My book on Wild Orchids of Florida says that these are seen from South Dakota, east to Nova Scotia, south to Texas and in Florida.  If you are lucky to see them in your area, take only photos and leave nothing behind but footprints…   Orchids are protected in many States.

Nodding Ladies Tresses

Nodding Ladies Tresses. 

Picked too soon.. in aBackyard Universe.

The little garden has been plodding right along, regardless of the intermittent just-under-a-freeze-warning type temperatures we have had here in South West Florida (today it’s warm out!)  I got home last night from my Avon Rep Meeting  and hubby had decided on his own to go pick one of the tomatoes that was barely starting to turn red!    It’s sitting here on the counter  more than likely destined for (gluten free) Fried Green Tomato to go along with dinner tonight.  I wish he hadn’t picked it.  His excuse;  “I thought I’d pick it so the animals wouldn’t get it”   WELL….  The only animals likely to get it around here are an errant wood pecker, blue jay OR human.  The Nasturtiums I planted from seed last month are still coming along.  The lettuce and collards are still producing as well.

a tomato alone..

Picked Too Soon!

The rest of the tomato bunches are doing OK…  so long as no one decides to pick any or take a bite…. The above and below are Bonnie Select Hybrid Tomato, Determinate.  They get 8 to 10 oz and are a good handful.  Maturity is around 75 days.  Water Tomatoes daily!   Check periodically for worms and bugs to pick off.  Interestingly enough, my Bonnie Tomato “Mortgage Lifter” and Black Krim are undersized plants with small fruits – they do receive the same treatments with water and fertilizer.

Tomato Bunch

Bonnie Select hybrid Tomatoes

The Cauliflower is just starting to head up.  I was taught that when it starts to head up like this you take some of the leaves and you cover the head up so it stay a nice white color.  Do you do this with your Cauliflower?  (I also like to put some of the leaves in salads for a little different flavor.)  Store bought Cauliflower does not compare to home grown!  It’s easy to grow, try it out in your Zone!

Cauliflower

I had no idea that while I was planting and taking care of the garden, the birds were also planting a Sunflower Garden.  OK, they were in cahoots with the squirrels hiding seeds..  The Black Oil sunflowers are almost as tall as me (5′ 4″) and are wonderful to see every day as they track the sun across the sky.  I’ve included another photo.  The two below are the tallest.

The Birds Flower Garden

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The most cool bird I have seen in the Backyard Universe  has been an American Goldfinch I sighted in the Labyrinth tree last month.  He was part of a small flock that passed through one evening.  You just never know what you might see from your backyard!  Spring is coming so get your small (or large) garden in, feed the birds and watch the magic happen around you!   Get the family involved!   If you need suggestions, drop me a note.

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