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Baobab Trees Facing Extinction

Declining populations of baobab trees have been a concern for more than a decade now. That concern has been amplified with the release of a recent study that shows that two baobab tree species endemic to Madagascar risk losing the majority of their available habitat due to climate change and human development in the coming decades.

Baobab trees are spectacular sights. Unique in appearance, they can grow up to about 100 feet tall with trunk diameters as wide as 36 feet and can live for hundreds (possibly thousands) of years. As the trees age, they develop hollow trunks used for storing water (as much as 26,000 gallons!) to help them survive long periods of drought. The fruits of baobab trees are coconut-sized and edible and are said to taste like sherbet. The leaves of at least one species are eaten as a vegetable, and the seeds of some species are used to make vegetable oil. Various other products, including fibers, dyes, and fuel are also derived from baobab trees.

There are nine species of baobab trees (Adansonia spp.). Eight are native to Africa and one is native to Australia. Two of the African species are also found on the Arabian Peninsula, and six of the African species are found only on Madagascar. Three of the Madagascan species (A. grandidieri, A. perrieri, and A. suarezensis) are listed as endangered on the IUCN Red List. Currently, A. perrieri has the lowest population of the three species, with only 99 observed trees. It is estimated that by 2080, its range will be reduced to 30% of what it currently is, further threatening its survival. A. suarezensis has a considerably larger population (15,000 trees) but a much smaller distribution area (1,200 square kilometers). By 2050, this area is estimated to be reduced to only 17 square kilometers, practically guaranteeing its eventual extinction. On the bright side, A. grandidieri has a population of about one million trees and an extensive range that should remain largely undisturbed in the coming decades.

An interesting component to this story is how giant tortoises fit in. The fruits and seeds of baobab trees are relatively large, and so their dispersal is best carried out by animals. Seeds that fall too close to the parent trees have little chance of survival since they will be shaded out and will have to compete with large, adjacent trees. Animals that eat the fruits of the baobab trees help to disperse the seeds by defecating them in areas away from large trees where the seedlings will have a greater chance of survival. Two species of giant tortoises that were once native to Madagascar but have now been extinct for hundreds of years were likely primary dispersers of baobab tree seeds. A recent study used a species of giant tortoise not native to Madagascar (the Aldabra giant tortoise) to test this hypothesis. The tortoise readily consume the fruit of the baobab tree. The seeds remain in the tortoise’s digestive system for up to 23 days, giving the tortoise plenty of time to move to an area suitable for seed germination. Given these findings, biologists are currently working to introduce Aldabra giant tortoises to Madagascar to help save the baobab trees.

Climate change, loss of habitat due to human development, and loss of seed dispersers due to extinction threaten the survival of some baobab tree species, but by recognizing this threat, biologists can work towards preventing their eventual extinction. As we gain a better understanding and appreciation for the need for biodiversity on our planet, we will resolve to take greater steps to protect it.

To learn more about baobab trees facing extinction and giant tortoises as seed dispersers, visit the Scientific American blog, Extinction Countdown, here and here.

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Adansonia grandidieri

photo credit: wikimedia commons

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Documentary: What Plants Talk About

Earlier this summer I posted a review of a book called, What a Plant Knows, by Daniel Chamovitz. It’s a book that describes plant senses – senses that are similar to human senses (i.e. seeing, hearing, smelling, etc.). Plants are much more aware of their surroundings than we might initially think, and so I recommend this book to anyone interested in gaining a better understanding of plants and their “awareness”. However, I also understand that this can be an intimidating subject – especially for those who haven’t spent much time studying plants and their biology. Chamovitz wrote his book with the intention of making this subject accessible to everyone. Anyone with even a limited understanding of biology should be able to understand the basic concepts in Chamovitz’s book. However, the subject can still be challenging.

Luckily, a recent documentary by PBS explores similar concepts. It simplifies things even more – exploring the ways in which plants communicate with the world around them, even without having the organs we typically attribute to communication and awareness (i.e. brains, ears, eyes, etc.). The documentary is called What Plants Talk About. I watched it recently and was reminded of Chamovitz’s book. They fit together so well. If you have any interest in this subject at all, I recommend both. If all you are after is a simple introduction, watch the documentary. If the documentary intrigues you, read the book.

There is a lot more to learn about plants and their “awareness,” but these sources are a great start. Watch the documentary and/or read the book and then let me know what you think in the comments below. Meanwhile, we wait in anticipation of what science might discover next concerning this remarkable aspect of the plant kingdom.

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Excerpt from Amanda Thomsen Interview

Plenty of books have been written about gardening and landscaping 101, but none are quite like Kiss My Aster by Amanda Thomsen. The title alone should clue you in that Thomsen’s approach is unique. Flipping through the pages it becomes more apparent. It’s a graphic novel. It’s a choose your own adventure book. There is a pink unicorn and a vampire reference, but there is also great information for those interested in gardening. Much of it is geared towards beginners, but seasoned gardeners will find it useful as well. This book is in a league of it’s own…so it’s certainly worth a look.

In the latest issue of Greenwoman Magazine, Sandra Knauf interviews Amanda Thomsen. It’s a lively conversation, in which Thomsen reveals how the book came about, among other things. What follows is an excerpt from that interview. Get your hands on a copy of the magazine for the full conversation.

Knauf: Who or what inspired you to become a gardener? A writer?

Thomsen: When I was little I wanted to do three things when I grew up: 1. Be a writer, 2. Recycle, and 3. Wear red lipstick. Happily, I have achieved these three goals. Although I always wanted to be a writer, I did ABSOLUTELY NOTHING to make that happen growing up. No one pointed me in the right direction. I’ve taken a few writing classes, but overall nothing that was memorable. I have always been super creative and have just looked for ways to demonstrate that!

My parents were the prototypes for yuppies. For some reason, and I think it was my dad’s Indiana upbringing, they were SUPER into Crockett’s Victory Gardening on PBS and did, literally, everything he did. We have a 30′ x 50′ victory garden each summer and I just grew up in it. They had a greenhouse added to the house, canned up everything from applesauce to giardiniera. It was a delicious way to grow up, and I didn’t realize that EVERYBODY didn’t have that until I was, like, 20. Maybe older. I didn’t realize there were jobs in gardening and horticulture.

Knauf: You have this funny, sassy, sexy, free-spirited, curse-word-strewn, delightfully naughty blog for a few years, and you’re a landscaper, and suddenly you’re blogging for Horticulture magazine’s website, and now you blog for Fine Gardening. I don’t want to disrespect these fine publications, but, well, they can be at times just a bit, shall we say, dry. How did you get together with them?

Thomsen: Horticulture asked me to join this contest they were having for a blogger. I did and I won. It was hard on me to blog exclusively for them and not on my personal blog at all – not even about personal stuff – but that was the deal. Fine Gardening has been a great, laid back home for my more horty things to say. I leave the eff-bombs at the door and get my freak on over there and I’ve loved it. AND they’ve given me a chance to write articles, which is seriously one of my happiest achievements in life…

All these magazines KNOW that if they are going to survive, they have to get new, younger readers, and I’m happy as a salami at a mustard party to help do that for them.

Knauf: How did the idea for a book come about?

Thomsen: I was dreaming about how to make books more interactive when I thought of the idea. Originally it was going to be SO comprehensive that I thought I’d need help writing it. You know, a backyard bible of sorts. Then I got this wack-a-doo idea of having a hipster gardening book that was illustrated with, you know those terrible IKEA instructions with no words and very vague symbolism? I wanted to do it like that. Carleen Madigan at Storey literally found me in a dumpster and asked me if I had ideas for books. We met up in Boston while I was there speaking, and I just LOVED her. She was totally the midwife of this book. I literally wrote the whole book for her and if I could make her laugh then I was golden. I wrote the whole book, and then they found the illustrators, which completely adds everything.  The illustrations are way better than the writing!

kissmyaster

Visit Amanda Thomsen’s blog: www.kissmyaster.co

Read the entire interview and more at Flora’s Forum.

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Autumn Leaves

It’s October, so fall is in full force in the northern hemisphere. Days are shorter and temperatures are cooler, but one sure sign that fall is here is that the leaves on deciduous trees are changing colors. Every autumn, leaves that were once a familiar green turn brilliantly red, fiery orange, or vibrantly yellow. And then they fall to the ground leaving trees exposed – just trunks and branches  – skeletons of what they once were during warmer and brighter days.

But why?

Surprisingly enough, the colors seen in autumn are largely present in the leaves throughout their lives, but we don’t see them. We only see green. This is because chloroplasts (cell organelles responsible for carrying out photosynthesis) contain chlorophyll, one of three main pigments found in the cells of leaves throughout the growing season. Chlorophyll absorbs red and blue light and reflects green light. Because chloroplasts are so abundant in the cells of leaves, leaves look green.

But carotenoids are hanging around, too. The second of the three main pigments, carotenoids protect chlorophyll from oxidation and aid in photosynthesis. They reflect blue-green and blue light and appear yellow, however their population is considerably smaller compared to chlorophyll, so their yellow color is masked.

When day length decreases, the level of chlorophyll in plant cells diminishes. As a result, the yellow color of the carotenoids begins to show. Also, a layer of cells called the abscission layer forms between branches and petioles (i.e. leaf stems). This abscission layer is what eventually causes branches to drop their leaves. As the chlorophyll begins to die off and the abscission layer forms, anthocyanins (the third of the three main pigments found in plant cells) are synthesized. Anthocyanins absorb blue, blue-green, and green light and appear red.

With chlorophyll virtually absent (and photosynthesis brought to a halt) carotenoids and anthocyanins become the major pigments found in leaves, giving them the autumn colors we are accustomed to seeing. But here is where it gets tricky…

Fall leaf color is largely dependent on various environmental conditions, including temperature, amount of sunlight, and soil moisture. If autumn is warm and wet, chlorophyll may be slow to die, and anthocyanins may be slow to form. Chlorophyll drops off more readily when it is cool and dry, and anthocyanins synthesize more readily when days are sunny. Dry, sunny days followed by cool, dry nights are said to offer the most vibrant fall colors. Additionally, global climate change is now playing a role, so fall colors may start to appear earlier or later or last longer or shorter depending on the region.

Do you have a favorite place to view fall foliage? Add your comments below.

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Cornus sericia – red-osier dogwood

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Ribes aureum – golden current

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Quercus palustris – pin oak

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Fraxinus sp. – ash

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Rhus sp. – sumac

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An Emerging Botanical Garden in Louisville, Kentucky

There is a new botanical garden being constructed in Louisville, Kentucky. It’s called Waterfront Botanical Gardens, and it is being built on top of an old landfill. The landfill was in use for several decades during the mid-1900’s and officially closed in 1973 when a new landfill site was opened. Recently, there was discussion about what to do with the old landfill site. Botanica, a group of plant lovers and devoted gardeners in Louisville, was able to work out a deal with the city to secure the 23 acre site and is currently moving forward with plans to turn it into a botanical garden.

Botanica’s vision for the garden is broad, but part of that vision includes educating the public about native flora and promoting environmental stewardship. Planning and construction are still at their early stages and there is tons of work ahead, but considering that people in Louisville have been wanting to see a botanical garden in their city for at least 30 years, watching it finally start to happen must be exciting. To celebrate the emergence of Waterfront Botanical Gardens, the Founders’ Garden was constructed and planted this spring. It is located near the site of the future botanical garden and is a small token of things to come. A picture of that garden (taken from the website) can be seen below.

I am excited to watch from afar as this new botanical garden emerges, and I hope to be able to visit someday after the garden has been constructed. To learn more about this garden and to follow its progress, visit their website: www.waterfrontgardens.org

waterfront botanical_founders garden

The Founder’s Garden at Waterfront Botanical Gardens

Louisville, Kentucky

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Wildflower Walk: September 2013

Recently I was on a seed collecting trip at Bannister Basin in Payette County, Idaho. From a distance, the area looks like a barren wasteland – especially this time of year. It is hot, dry, and brown. The rolling hills are mostly bare except for dried up weedy grasses and occasional shrubs, and there isn’t a single tree in sight. However, a short hike through the area reveals some interesting plants and bits of color scattered among the drab landscape. It was obviously not the best time or place for a wildflower walk, but the following pictures show a few of the flowers that I was able to find. These are tough species, flourishing in a harsh environment.

chrysothamnus viscidiflorus

Chrysothamnus viscidiflorus – green rabbitbrush

machaeranthera canescens

Machaeranthera canescens – hoary tansyaster

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Eriogonum strictum – strict buckwheat

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Eriogonum sp. – buckwheat

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Plants on Rooftops in South Carolina

Here is a video featuring a couple of folks in South Carolina introducing green roof technology. I have a particular interest in green roofs that stems from my fascination with plants and my interests in urban ecology and being environmentally conscious.  I will eventually post more about green roofs and urban ecology as I have already promised. This should tide you over for now.

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Plant vs. Bike

Summer is drawing to a close in the northern hemisphere. Days are getting shorter. Nights are getting cooler. Fall flowers are beginning to bloom. And bicycles are getting more flat tires.

As an avid bicyclist, I am particularly aware of the waning summer season, especially since I live in a region where Tribulus terrestris is a prevalent weed. Commonly known as puncturevine or goathead, this nuisance plant is the bane of many cyclists’ existence. While the plant itself appears innocent, its fruit is quite the opposite. Rough around the edges and bearing large, rigid spines, puncturevine fruits easily penetrate bike tires, causing flats. They can also result in an uncomfortable experience for the bare-footed.

Native to the Mediterranean region, puncturevine made its way to North America sometime during the European immigration and has since spread across the continent. The fruit of puncturevine is called a bur. Plants with this type of fruit are benefited in two main ways: herbivory deterrent and seed dispersal. The spinyness of the burs deters insects and animals from eating their seeds, and the spines of the burs attach to the feet and fur of animals, etc., aiding in the dispersal of their seeds.

In cool climates, puncturevine is a summer annual. It appears in the heat of the summer, and by late summer the plants have mostly died off, leaving behind hordes of burs, awaiting the arrival of unsuspecting animals, bike tires, and otherwise. The spines of the burs attach themselves to these unsuspecting vicitims and are spread far and wide. The plants typically grow prostrate but can grow upright when they are in shade or being crowded out. They produce large mats that can spread as wide as 6 feet. Their leaves are oppositely oriented and are pinnately compound. Their flowers are small with five bright yellow petals that appear singularly in the axils of leaves. Their fruits are burs that split into 4-5 sections, each containing 1-2 large spines. Their seeds can remain viable for up to 20 years. Puncturevine is a fast growing, drought-tolerant plant with a long, slender taproot. It is commonly found in disturbed sites, along roadways and walkways, and in pastures and fields.

While I am fascinated by this plant, I also abhor it, and so I make an effort to remove and kill it whenever possible. If it weren’t for the countless flat tires it has caused me, I’d probably be more willing to let it be. Bike enthusiasts who have experienced this nuisance nod in agreement.

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Tribulus terrestris looking sweet and innocent

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Close-ups of pretty flowers, interesting leaves, and evil burs

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Bur of puncturevine puncturing bike tire

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A Plant Community’s Response to Climate Change

The threat of ensuing climate change has led many to consider what the future might look like for life on earth. Plant life will undoubtedly be affected, and numerous observations have already been made indicating that plants and plant communities are responding to changing climates.

A recent study, published in Ecology and Evolution, documented changes in the lower elevation boundaries and elevation ranges of common plants found on the Santa Catalina Mountains (near Tucson, Arizona). A study of this caliber is rare because there is relatively little data available to observe such changes over a long period of time. The scientists that carried out this study were able to use survey data collected by Robert Whittaker (the father of modern plant ecology) and William Niering in 1963. Whittaker and Niering conducted an extensive survey of plants along the Catalina Highway, which still exists today and runs along the southern slopes of the Santa Catalinas. Following similar data collection methods, researchers from the University of Arizona surveyed plants along the Catalina Highway nearly 50 years after the original survey. What they found confirmed predictions: montane plants in the southwest are responding to a warmer and drier climate by shifting their lower elevation limits upward.

The average annual air temperature in this region has increased an average of 0.25 degrees Celsius per decade since 1949. Also, rainfall has decreased significantly since Whittaker and Niering’s original plant survey. Twenty seven of the most common plant species were selected from the new survey and compared to the original survey data. Fifteen of the twenty seven species (56%) have significantly shifted their lower elevation boundaries, moving further up the slopes of the mountains to escape higher temperatures and reduced rainfall. Some of the plant species have also shifted their upper elevation boundaries, with four of them moving further upslope and eight of them moving further downslope.

The authors of this study state that “even a casual observer could recognize changes in plant elevation boundaries.” Alligator juniper, bracken fern, beargrass, and sotol are examples of plants in the Catalinas that have noticeably migrated upslope and are no longer found at lower elevations where they were once common. Alligator Juniper (Juniperus deppeana), for one, was once documented growing at least as low as 3500 feet, but now does not occur until after the 5000 feet mark.

This rare opportunity to compare current plant survey data with old data paints a stark picture regarding the effects of climate change. As plants and animals are forced upslope to escape warmer and drier climates, they may eventually find themselves with nowhere to go and ultimately end up extinct, reducing overall biodiversity on the planet. The authors of this study conclude their findings with this statement: “The shifts in plant ranges we observed in the Santa Catalina Mountains indicate that the area occupied by montane woodland and conifer forests in the Desert Southwest is likely to decrease even more with predicted increases in temperature, and that regional plant community composition has and will continue to change with further warming as plant species respond individualistically to changing climates.”

Read more about this study at the University of Arizona news site.

alligator juniper_juniperus deppeana

Alligator Juniper (Juniperus deppeana)

photo credit: wikimedia commons

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Interview with Peter D’Amato of The Savage Garden

In my last post about sundews, I referenced a book about carnivorous plants called, The Savage Garden, by Peter D’Amato. Earlier this month, a revised edition of The Savage Garden was released by Ten Speed Press. Recently, D’Amato appeared on Real Dirt, a garden podcast hosted by Ken Druse, to tell his story, promote the revised edition of his book, and talk about carnivorous plant cultivation. It’s a fascinating discussion, and I highly recommend checking it out.

real dirt

Also, check out the website for Peter D’Amato’s carnivorous plant nursery, California Carnivores.