Legumes: Self Fertilizing Plants

The green stem of the legume palo verde tree in the Sonoran Desert.

Determining how to fertilize a plant can be quite the difficulty.  You may have heard that most people over water their plants, but it is also true that most people over fertilize their plants.  Certain plants however never need to be fertilized simply because they have "figured" out a way to fertilize themselves.  Bean plants, also called legumes, form a symbiotic relationship with a bacterium known as rhizobium.  The air we breath is about 70 percent nitrogen, an essential nutrient for plant fertilization.  Atmospheric nitrogen however cannot be used by plants, it must be converted into a different form called ammonium.  Rhizobium bacteria has the ability to take nitrogen gas and convert it into ammonium.  This changing of nitrogen gas into ammonium is known as nitrogen fixation. 

Using legumes in the garden can be quite a useful way to fertilize your plants naturally.  Farmers in the Midwest will often alternate between corn and soybeans, taking advantage of the fact that soybeans naturally replenish the soil with nitrogen fertilizer that the corn can use.  In deserts, which have soils that are naturally deficient in nitrogen, plants must either be adapted to living in soils with low nutrients or have the ability to fix their own nitrogen.  For this reason, legumes are extremely common in desert ecosystems.  Legumes are not just your typical bean plant, they also grow into bushes and trees.  In the Sonoran Desert palo verdes, mesquites, ironwoods, and acacias are all small legume trees that form bean-like pods.  Typically, these legume trees will form islands of soil under their canopy that are rich in nutrients compared to soils beyond the canopy.  Because of the slightly richer soil many smaller plants will often be growing in this micro-environment. 

The darker growths on these plant roots are tumors infected with rhizobium bacteria.

Legumes and Rhizobium bacteria form their association with each other in the soil-root environment.  Rhizobium are naturally occurring soil bacteria but don't really do much if they haven't infected a legume.  When bean seeds germinate and begin to grow, rhizobium already present in the soil infects the new plants roots.  Points of rhizobium infection in the roots form into tumorous-like growths which are like little nitrogen fixing factories.  Typically we think of tumors as unhealthy but be assured, this type of plant tumor is very healthy and beneficial to not only the infected plant but also to the entire environment.  Legume plants that for some reason are not infected become extremely anemic with stunted growth and yellow coloration. 

Organ Pipe Cactus National Monument

View from the visitors center trail at Organ Pipe Cactus National Monument.  In this photo jumping cholla, saguaro, and organ pipe cacti can all be seen with the Ajo mountains in the background.

Organ Pipe Cactus National Monument is located right on the boarder of Mexico as far south as you can go in Arizona. The monument is quite a ways off the beaten path and probably the most dangerous monument in the national park system. There are multiple boarder patrol checkpoints that are actually in or near the park and boarder patrols can be found all over the park. Tragically, a few years back a park ranger was killed in a boarder incident and things were quite dangerous within the park. Today however, a barrier fence has been put into place along the monuments boarder and dangerous sections of the park have been closed to visitors. The park is significantly safer today than it was several years ago. Unfortunately, Senita Basin, the only population of the columnar senita cactus is currently closed due to these issues. Fortunately, other sections of the park such as the Ajo Mountain Drive are open and offer spectacular views of the Sonoran Desert. For a desert, the monument is quite green and hope to a decent amount of vegetation. This unusually green desert is a result of this particular desert being one of the wettest deserts in the world. Organ Pipe receives about 10 inches of rain annually with significantly more falling at higher elevations. Both winter and summer rainfall seasons also contribute to the amount and diversity of vegetation here.

View along the Ajo drive in Organ Pipe Cactus National Monument

A total of 28 species of cacti can be found within the park. Several of these are at their northern most limits, and are prevented from migrating further north due increased number of days with freezing temperatures to the north. Organ pipe cacti are one of these species and can be found in abundance within the park. The amazing diversity of cacti can be found on the Ajo Mountain Drive, and it is spectacular for organ pipe viewing. Most commonly, the organ pipe is found on upper slopes facing south. The sun warms southern slopes just enough to prevent colder freezing temperatures that prevents the cacti from growing on colder northern slopes. Upper slopes also are slightly warmer due to warm air rising up these slopes. If the growing tissue of an organ pipe freezes for too long of a period of time or too many times in the winter it will kill the plant. So these slightly warmer areas give the cacti an added edge so they can become established. I also have a strong suspicion that organ pipes prefer soil types typically found on upper bajada slopes. Even with this added warmth however, conditions are not absolutely perfect. The organ pipe sill needs some help from what is called a nurse plant. Small shrubs, mesquites, ironwoods, and palo verdes all help protect young organ pipes from the intense summer heat and sun. The cooler temperatures and shady conditions also help hold the water in the soil for longer. On occasion, large rocks can even provide these added benefits of shadier, cooler, and slightly wetter conditions. Nurse plant associations can be found for several different species. The saguaro cactus has very similar nurse plant requirements. A different type of nurse plant association that can be found within the park is that of the jumping cholla and pincushion cactus. The jumping cholla is a rather large shrubby-tree like cactus that looses an abundance of spine dense joints. These joints naturally fall from the cholla and often will form a mat around the mother plant. Nothing really wants to go close to these piles of spiny cactus joints making it a perfect place for the small pincushion cactus to live.

Organ pipe cactus

Mistletoe: The Kissing Parasitic Plant with a Gross Background...

This is a post from two years ago but I thought it worthy of reposting.  Mistletoe has such a fascinating background and considering the time of year...

For many years now, every time I see mistletoe hanging-up around Christmas time I find it sort of humorous.  Most people think of mistletoe as the "kissing" plant.  While I also think of it as the "kissing" plant, I also think of its complex parasitic life-cycle.  Yes, mistletoe is a parasite, and is pretty common in western forests and deserts.

A clump of mistletoe growing in the center of a juniper tree.

However, parasitism is only the beginning of the story.  Even more interesting is how the mistletoe got on the tree in the first place.  Mistletoe produces red or white berries which are possibly toxic to humans but extremely tasty and nutritious to birds of all types.  Many types of birds will gorge themselves on the berries and as a consequence carry the seeds to new locations.  In-fact, a southwestern bird known as the pheinopepla was found to eat around 1100 berries a day when berries were available.   Eating all those berries means a lot of seeds being transporting to new plants that baby mistletoes can parasitize.

Phainopepla, found to eat around 1100 mistletoe berries per day when berries were available.

Seeds are transported in the birds digestive tract but also on their beaks.  Mistletoe berries are covered with a very sticky substance causing seeds to stick to the birds beak, which the birds wipe off onto trees and shrubs where a new plant can grow.  The sticky seeds also pass through the digestive tract of birds and when defecated on a plant can germinate and parasitize the new plant very quickly.

Desert tree severely parasitized by mistletoe.

From all this you may think that mistletoe is a severe problem taking over and destroying our forests, but things to not always as they first appear.  In many cases mistletoe actually benefits the forest.  First of all the berries provide food for bird species that live in the area, increasing the number of birds and number of bird species an area can support.  Secondly, some trees, such as the junipers, when parasitized actually produce more of their own seeds.  This also increases the food available for birds and animals, thus supporting greater numbers of animals and greater diversity as well.  Parastized trees also form deformed 'witches brooms' which many birds and animals prefer for nesting sites. 

So the next time you see mistletoe hanging in the doorway, wow your "kisser" with this knowledge and they may never look at mistletoe in the same way.  They may not want to kiss you after their new found knowledge either though...  But this may be a good thing...

Barrel Cactus Part 2

California barrel cactus, Ferocactus cylindraceus.

Barrel cacti are kind of as their names imply, barrels full of water.  The problem is, the water isn't just hanging out in the cactus like a big glass of water.  The water is stored inside of the cells that fill the interior of the cactus.  The best way to get this water is to eat the tissue, though it won't taste very good and probably will make you sick.  The thick layer of hooked spines will also deter any person or animal from easily accessing this water though.  In drought however, the barrel cacti is one of the best sources of water for desert animals there is, that is, if they can get through the spines.  Small animals like rats, chipmunks, or mice can avoid spines by burrowing underground slightly to where there are no spines and then eating up into the cactus.  I have actually found a few barrel cacti that have been entirely hollowed out by rodents, yet have there skin and spines fully intact.  Larger animals such as deer have no such luck though accessing moisture from a standing barrel cactus though.  The spines become just too big of a deterrent.

Red spines of the barrel cactus show up after being wet by rain.

Fortunately, for larger mammals the barrel cactus has a fatal flaw.  As a barrel cactus grows it generally leans towards the southwest, which is the direction from which the most intense sun comes from.  Nearly all barrels lean to the southwest, just as a compass always points north, thus the common name compass barrel.   It might seem that leaning in the direction of the brightest sunlight might mean the cactus is trying to gather as much sunlight as possible.  This is however the exact opposite of what it is doing.  With the top of the cactus pointing directly at the most intense sun, spines at the top actually shade out much of this light and all sides of the cactus actually avoid this direct sunlight.  The sides however gather the most sunlight from the sides, as the sun comes up or goes down, when the sun rays are less intense and therefore less damaging to the cactus.  Pointing tops towards the most intense sunlight is therefore actually a protection mechanism, rather than a gathering mechanism, against intense sunlight.

A barrel cactus that fell over due to leaning towards the southwest.  Even though this cactus fell over, it continues to grow.

Leaning is an important adaptive strategy of the cactus, but is this strength also lays a huge weakness.  As the barrel cacti grows and leans it becomes very off balance.  Older, large cacti will often simply fall over.  Oddly, even when the cactus falls over it will continue to live and grow as it lives laying on the ground.  Once the barrel cactus falls over, the underside of the cactus is exposed which is unprotected by spines.  Large mammals will often start eating the barrel from this unprotected portion during drought.  

Flower of the California barrel cactus Ferocactus cylindraceus.

Barrel Cactus Part 1

Compass Barrel cactus

The barrel cactus is one of the most common cacti in the Southwest.  There are four different species common to this area of the country, the most common of which are the compass barrel and the California barrel.  It can be extremely difficult to distinguish between these two common species of barrels.  In southern Arizona, such as around Tucson, the compass barrel is the most common of the two cacti.  In central Arizona such as around Phoenix, southern California, and even into the depths of the Grand Canyon the California barrel cactus is the most common.  Their ranges overlap in central Arizona and their similarities are pretty extensive.  Without closer investigation you may not be able to determine what specific species a particular barrel is, there are however a few differences that may help in identification.  First off is shape.  Of course, barrel cacti are all sort of barrel shaped.  The compass barrel is a little more wide and plump than the California barrel.  The California barrel  is a little skinnier.  The second way to distinguish between the two is by looking at the spines.  Both have very interesting spines which are often red colored.  This red coloration gives a sharp contrast to the dark green of the cacti's body, especially after a rare rainfall.  Both cacti also have flattened central spines that have a ribbing pattern on them.  The central spines are also hooked, giving both cacti another common name of fishhook barrels.  Compass barrel cacti spines are however considerably more hooked than California barrels.  Compass barrel central spines are a full "fishhook" shape and were in-fact used as fishhooks by some Native Americans.  California barrel central spines are closer to a 90 degree curve than an actual fishhook.  These are the best ways, though not necessarily foolproof ways of distinguishing the two while out in the desert.

In our next post we will talk about the leaning habit of barrel cacti.

California barrel cactus front left of picture.

Bringing Back the Dinosaurs... Sort Of...

Picture of a hadrosaur based off of findings from the dinosaur mummy "Leonardo".

In our last post we discussed how it has recently been discovered that some dinosaur fossils contain remnants of soft dinosaur tissue. In this post we will discuss the discovery of a fossilized dinosaur mummy.  Specifically, this dinosaur is a hydrosaur, or a duckbilled dinosaur, that died and was quickly buried in sediments before it could decay.  The burial process mummified the dinosaur, preventing decay and eventually the mummy was fossilized.  This dinosaur mummy is different from say human Egyptian mummies in that the dinosaur is actually fossilized and rock.  Egyptian mummies are simply well preserved tissues of the human that died.  As a result of the dinosaur mummy fossilizing, all of the parts of the dinosaur present in the mummy are still present today in rock form.  The process of fossilization of dinosaur mummies is exceedingly rare and have only been found a handful of times.  The awesome thing about mummies is that they preserve the soft tissues such as internal organs or skin which normally decay away long before any scientist can observe them.  The difficulty with fossilized mummies though is the fact that all of the soft tissues are now actually rock, which obviously is extremely difficult to dissect.  The documentary movie "Secrets of the Dinosaur Mummy" shows how modern day paleontologists "dissected" Leonardo without hacking him up.  The movie is a great demonstration of real scientists doing real science.  As a result of the "dissection", the scientists were able to find out all kinds of interesting biology about the dinosaur.  Huge changes in what we believe about dinosaurs in how they look and how their body functions have come about because of the investigation shown in this movie.  Also interesting, since the movie has been filmed, soft tissues like we talked about in our last post also have been found in Leonardo. 

Secrets of the Dinosaur Mummy
 

Actual fossilized dinosaur mummy "Leonardo".

Is Jurassic Park Possible? Bringing Back the Dinosaurs

Dinosaur soft tissue found in a fossilized T-Rex leg bone.

Is Jurassic Park really possible?  For nearly twenty years scientists have been telling us that the science behind the movie Jurassic Park is possible in theory, but not really possible in practice.  Why?  No one has ever or would ever be able to find intact dinosaur DNA from ancient fossilized bones, or mosquitoes for that matter.  Oddly though, about the time the movie was coming out, a paleontologist discovered the remains of some organic soft dinosaur tissue in a fossilized dinosaur bone.  How in the world would tissue survive such long periods of time and the fossilization process?  The answer to that question is that no one really knows, but several scientists working independently of each other have been able to verify the presence of dinosaur tissues in fossilized bones.  Organic molecules, including blood cells, have been found and confirmed in these specimens.  These samples open up a totally new area of paleontology and biology that has previously never been open for scientific examination before.  For example, through the examination of protein sequences, specifically collagin, scientists have been able to find that dinosaurs were closely related to birds.   Several different proteins have also been found in these fossils.  These proteins may open doors to understanding dinosaur physiology such as if they were warm or cold blooded.  Currently though, the field of studying ancient tissues from fossilized specimens is still highly controversial.  Even though there has been a lot of evidence to support the existence of this tissue and that it is not simply environmental contamination, the fact remains that it is still nearly unbelievable that organic soft tissues would survive decay over such long periods of time.  Though proteins have been found, no intact DNA has been found.  This makes sense considering protein molecules are significantly more stable than DNA.  So unfortunately, the search for dinosaur DNA and for Jurassic Park continues.  But with this discovery, we will get a lot closer to determining what a real dinosaur was like and what a real Jurassic Park would be like.

http://www.smithsonianmag.com/science-nature/dinosaur.html

In my next post I will discuss another, even more recent dinosaur finding which is even more amazing than this discovery.

What Makes a Chili Pepper Spicy?

The chili pepper was first cultivated and bred for its spiciness in Central America, hundreds of years before any part of the rest of the world enjoyed it.  During this time, ancient Americans spiced all kinds of food with the chili.  In the southwest United States, Native Americans would gather wild chiltepine chilis and protect the plants for future use.  Aztecs were said to enjoy hot cocoa spiced with chili peppers.  When explores from the Old World began visiting North and South America in the 1500's they brought the chili to the rest of the world.  Now, the spiciness of the chili pepper has captured the taste buds of nearly the entire world.

It is amazing how the spiciness of the chili has been utilized in nearly every cuisine possible.  Even if a recipe is not made with the spice of chilis many people will put some sort of spicy sauce on it.  Think about Tabasco Sauce. people will put it on just about everything.  There is probably someone that puts it on there cold cereal in the morning.  The odd thing is, spicy flavor is painful and for some reason people like the pain (myself included).  Enjoying the spicy pain is a learned taste and some people can build-up quite a tolerance.  At least for decades, if not for centuries and millenniums, people have been trying to breed the next spiciest chili pepper.  It seemed for years the habanero held the record for spiciest chili.  In recent years a number of chili's have claimed to be the spiciest in the world.  Recently, the ghost pepper, also known as the naga bhut jolokia, from India held the title of worlds spiciest chili.  Now the trinidad moruga scorpion pepper holds the official Guinness World Record for spiciest chili. 

The secret to the chili's spiciness is the molecule capsicum.  This molecule is secreted by the white tissues holding the seeds inside the pepper.  Capsicum binds with pain receptors in the mouth responsible for detecting heat, therefore giving the spicy heat chilis are known for.  The body then responds by increasing perspiration, raising heart rate, and releasing endorphins.  Capsicum also has been shown to kill certain types of cancer cells and may indirectly aid weight loss.  In the wild, birds love spicy chili's, and mammals generally hate the spiciness (except for some humans of course).  When birds eat chili's the seeds pass through their digestive tract undamaged and can therefore germinate and grow if deposited in an ideal location.  The chewing and digestive tract of mammals however digests the seeds, preventing them from passing through the digestive tract.  This is exactly why chili peppers were spicy to begin with.  Caspicum deters mammals from eating them and to encourage birds to eat them, thus allowing the perpetuation of chili plants.  Cultivated varieties of chili's however are increasing in spiciness simply because humans are selectively breeding only the spiciest chili's in order to produce an even spicier chili. 

Fall Bird Migrations: Where do all the birds go?

From grade school we are taught that birds fly south for the winter to where it is warmer and north for the summer to where it is cooler.  Of course this is true but is obviously over simplified.  Birds don't just go south or north, they actually go to specific locations.  Scientists and bird watchers have tracked the migratory movement of birds in an effort to answer the question: where do birds actually go?  By tagging birds at their breeding grounds and then tracking the tagged birds as they migrate scientists were able to answer the question.  Watch the following video to see where birds go after they migrate south from Alaska for the winter.  It is amazing how Alaska has such a huge concentration of breeding birds in the summer that populate so much of the world as they migrate south.  This leaves us with very good reason to protect Alaska bird breeding grounds in order to protect many bird populations throughout the world.  It is also interesting that not all birds actually migrated south in the study, some actually migrated north from Alaska.  I suppose they migrated north across the North Pole so they could migrate south on the other side of the world. 

The colored dots in the video represent locations where birds originating in Alaska were found as the migrated.

Creosote Bush

The Creosote Bush (Larrea Tridentata) is a relentless desert plant growing in the deserts in both North and South America.  In North America it is found in the hot Mojave, Sonoran, and Chihuahuan Deserts where it is possibly out numbers all other perennial plants.  The only North American desert where it is not found is the Great Basin, simply because it is too cold.  The Creosote is so relentless it can occupy the poorest soils in flat basin areas between the mountain ranges of these deserts.  Driving through the flat lands of these deserts you can drive mile after mile past near mono-cultures of this plant.  Its roots are so effective at extracting moisture from the soil that it is often very difficult for other plants to become established near Creosote.  Creosote roots can extract water from soil that is seemingly dry, surviving up to two years without rainfall.  They can also extract nearly all water from the soil, thus preventing any from ever reaching the water table. Creosotes are so good at all this that they can in-fact survive for over 11,000 years!

Bringing back the Wooly Mammoth

The last known population of Wooly Mammoths went extinct about 4,000 years ago.  The last population existed on Wrangel Island off the coast of Siberia.  Wooly Mammoths were extremely elephant like in both size and shape.  The big differences though between the two lies in their adaptation to climate.  Modern day elephants are adapted to the tropics.  Wooly Mammoths had fur similar to yaks and a thick layer of fat to help hold in heat.  Mammoths also had smaller ears which helped them hold heat in better.  These adaptations are of course why the mammoth lived in the icy tundra and thrived during the ice age.  As the world warmed, bringing the ice age to an end, suitable habitat and areas of food shrunk significantly for the mammoth.  The warming climate along with increased human hunting pressure at the end of the ice age led to the extinction of this huge mammal. 

Even though the mammoth has been extinct for 4,000 years now, scientists are working to clone one back to life again.  The process is simple in theory.  Scientists must first find a living mammoth cell and extract the nucleus.  The nucleus of a modern day elephant embryo must be removed and replaced with the mammoth nucleus.  Then, this embryo must be impregnated into an elephant mother.  If the embryo survives, a baby mammoth will be born to the mother elephant.  All of these processes are well known and have been successfully carried out, but never for wooly mammoths.  In practice however, this process appears nearly impossible.  The first step of finding living mammoth cells is what makes this so difficult.  But once living cells are found, the rest of the process would be relatively simple.

The preference of mammoths for icy cold habitats is what makes this entire process possible in theory.  As mammoths died in the frozen tundra, there is the very likely possibility their bodies would have frozen very quickly, thus preserving living cells in a frozen state.  Indeed, many frozen specimens of ancient mammoths have been found.  Not a single living cell in these frozen specimens has been found though and the probability of a cell surviving thousands of years even in a frozen state isn't very high.  It is still possible though.  And just the fact that it is possible makes at least a few people want to try.  Just think how awesome it would be to go visit a living wooly mammoth at the zoo.  Or see a wooly mammoth performance when the circus comes to town.  OK, that's sort of silly but just think...

Post Summer 2012 Sonoran Desert Monsoon Season Photos

The high humidity and rain from monsoon season seems to be gone from the Sonoran Desert this year.  There is always a chance that it can come back, but as far as monsoon seasons go, this year was a good one.  The vast majority of the Sonoran Desert received more than the normal amount of rain and cooler than normal temperatures over a two and a half month period.  This had a great effect on greening the desert, wildflower blooms, an explosion in bugs, and increased wildlife activity and reproductive success.  Below I have shared a number of photos I took on a recent hiking trip the day after the last rainstorm we received. 

A leafed out ocotillo. 

Not sure what this catapillar is but I found thousands of these along the trail.

Butterflies are quite abundant now as a result of the rains.

Viguiera

A green desert grassland of Tobosa located near the top of the White Tank Mountains.

Trailing four o'clock

Monsoon Season: Breaking the Desert Drought

About two months ago I posted on how a 4th of July storm broke a severe drought we had been experiencing throughout all of 2012 (Monsoon Season and the Drought).  As always with desert rain patterns though, you never know if the rain is going to keep coming or if a single rainfall event was just a fluke.  Fortunately, we have had a pretty good monsoon season that began with an earlier than normal large rainfall event and still seems to be going.  As of now, most of the desert surrounding Phoenix has received about three inches of rain in the past two months, which is slightly above average.  As a result of the rain and additional humidity, temperatures have actually been cooler than normal.  We of course have had our 110 degree plus days, but nothing like what we have had the past several years. 

The effects of rainfall on the desert over the past two months has been quite dramatic.  The drought had been so severe that mesquites and acacias had gone leafless which is fairly rare.  Ironwoods also were loosing many leaves and yellowing, which is extremely rare.  Other plants such as wolfberry and palo verdes were also leafless.  Creosotes were loosing leaves quickly and leaves that did remain were often brown or yellowish.  Nearly all triangle leaf bursage looked as if it were completely dead and often brittle bush was just a bush of white crispy sticks.  As you looked out across the desert in late June it appeared to be a crispy brown landscape without much life.  The rain however changed all this very quickly.  Within days of the first rain, new bright green leaves began to sprout.  The sustained rain allowed for these leaves to keep growing and for new stems to begin growing also.  Creosotes show this dramatic change quite well.  Creosotes still retain some of the old more brownish leaves from the drought period.  Directly above these brown leaves though bright green leaves are growing like crazy.  Ironwoods, palo verdes, wolfberries, mesquites, and acacias are also all full of leaves.  One thing I love about the desert after rain is all the different shades of green that color the landscape.  Each one of these plants has a slightly different shade, from the dark thick green of the ironwood, to the yellowish light green of the palo verde.  There also has been enough rain for the wolfberries and creosotes to flower.  Many wolfberries are in-fact loaded with fruit right now as a result of the rain.

All of this has had very positive effects on the wildlife.  I have noticed good populations of gambles quail as well as some healthy rabbit populations.  I am also sure many of the song birds are benefiting by the increase in berries and bugs.  The additional water and grass growth should also be having a positive effect on mule deer, hopefully increasing fawn survival.

So for now, the drought has been broken and with continued rainfall we can hopefully keep from returning back to drought conditions.  As of now, the National Weather Service is predicting the return of El Nino this fall and winter, which often means more rainfall.  A lot of weather scientists hold La Nina responsible for the drought in the Southwest over the last few years. 

Life of a Maple Part 5: Maple Incline and Decline

Healthy sugar maple forest.

It is very likely that prior to European settlement that deciduous forests of eastern North America were actually more disturbed than they are today.  This presettlement disturbance however was much different from the disturbance we see in our forests today.  Today, we see grazing, logging, invasive species, and widespread agriculture as the major forms of disturbance.  During presettlement days fire was the most common type of disturbance of the forest.  Just like the modern disturbances, it is very likely that fire was also human caused in a vast majority of cases.  Given the wet nature of eastern deciduous forests, it is extremely unlikely that fire could have been anything other than human caused.  While today's disturbances are typically an after though to land use, Native Americans purposely used fire to manipulate the landscape, increasing its productivity, and health. 

Fire however, strongly works against the maple tree.  Remembering back to previous installments of this series on maple trees, you might remember that maples prefer very stable, undisturbed habitats.  Anytime fire comes around one of these habitats where maples have become established, the maples are killed off.  As a result, prior to European settlement of the eastern deciduous forest oaks, a fire adapted species were far more abundant, and maples, a fire intolerant species were far less abundant.  By some estimates in some locations there may be up to three times more maples today than there was in the 1800's.  The increase of maples over the last century is a result of fire suppression by European settlers.  It was only on the best soils, in the most ideal habitats where fire didn't touch that maples were found in the 1800's and prior. 

Sugar Maples in fall.

As fire was suppressed and forests began to stabilize, maples began to expand there range.  Maples increased, invaded, and replaced forests that historically had been filled with oaks.  Oak forests typically are far drier and have poorer soil than ideal maple forests.  Oak forests were naturally more prone to fire and therefore easily survived.  But without fire maples moved in. 

Maples moving into areas of less than ideal soil wasn't the best thing for the forest.  Being maples are extremely picky about their environment, living in these less than ideal soils made them especially sensitive to drought.  Oaks are adapted to drought but maples are not.  Maples ideally overcome drought simply by living in the best soils in the forest.  But in less than ideal soils, the maples were damaged during drought.  The damage did not end with drought though.  Drought damage made the tree more susceptible to other problems such as fungal infections and insect damage which often end up killing the tree.  So the incline of maples was a direct result of fire suppression allowing maples to move into marginal habitats.  Maple decline is a result of maples living in these marginal habitats.

Forest where many of the maple trees are dying due to "maple decline".

Life of a Maple Part 4: Maple Syrup

If the Sugar Maple tree is famous for anything, it is famous for maple syrup.  Early each spring as the snow melts, maple syrup farms spring to life from the Midwest U.S., Northeast U.S., and Southeast Canada.  I personally have payed a few visits to these farms and they are always quite an interesting experience.  The weather is typically beautiful with temperatures between 30 and 50 degrees.  This is at least beautiful compared to the previous winter months.  Snow is typically on the ground but melting, which is producing the next most memorable thing about most maple syrup farms: mud.  The farms I've visited are always unbelievably muddy.  They are so muddy in-fact that horses are often used to gather sap.  Horses are used rather than tractors or other vehicles simply because they don't get stuck in the mud! 

The story of how maple syrup is made begins with the previous late summer.  Late in the summer, the maple tree stops growing and instead stores energy in the form of starch.  This starch is stored in the trees sapwood through the winter.  Come spring when sapwood temperatures reach about 40 degrees the starch is converted to sugar by an enzyme and moves out of the wood and into the tree sap.  Rising temperatures, particularly in the morning as the sun comes up, cause the sap to rise through vessels.  The sap rises towards the trees twigs and branches where the sugar will help the tree to begin flowering and budding. 

A large maple tree with two taps and buckets for collecting sap.

As the sap rises, if a tap is in place, some of the sap will drip out of the tree.  This sap generally contains about 2-3 percent sugar and is collected in buckets hanging from the tap.  One Sugar Maple tap can produce 5 to 15 gallons of sap.  Once the sap is gathered from multiple trees it is boiled down to evaporate off the water and concentrate the sugars to form maple syrup.  Typically 40 gallons of sap will produce about 1 gallon of maple syrup.  While sugar maples are the most common tree for producing syrup, red maples, black maples, silver maples, and even boxelder trees (also in the maple family) all can produce syrup. 

Maple syrup was first discovered by and utilized by Native Americans.  Europeans quickly picked-up on the practice and refined it to the practice we see today. 

Earthworm Invasion

Northern Maple forest without earthworms.

As odd as it might sound, earthworms are not native to the northern United States and Canada.  Why? Well, as glaciers receded from the northern portion of North America 11,000 years ago, they left behind a bitterly cold and extremely muddy waste land.  These glaciers reached from the north to their southern the extent of present day norther Iowa, Illinois, and Indiana.  Along this southern extent of the glacial line and northward there have been no earthworms until recently.  Worms simply couldn't survive the frigidly cold temperatures and frozen tundra when glaciers were present in these areas.  Further south however, where glaciers never reached, earthworms have been around for a long time. 

Within recent decades however, earthworms began showing-up in these formerly glaciated soils of the north.  This might not seem that weird until you realize that earth worms travel an average of 5 or 6 yards a year.  Over 11,000 years that equals only about 40 miles, which is a ridiculously slow rate that wouldn't have even allowed them to travel across an entire state.  Even if you double or triple that distance it doesn't even come close to the distance the worms would need to travel to show up in these northern forests.  So how did they move thousands of miles in just a few decades?  The only explanation is that humans carried them.  Fishermen and gardeners are especially notorious for carrying earthworms long distances.  As a result, worms were accidentally introduced to new locations hundreds of miles away from the nearest native worms. 

Northern Maple forest with earthworms.

Most people might think this is a good thing.  Worms are very good for garden soil after all.  The reality is though, worms are not very good for northern forest soils.  Worms are extremely efficient at what they do, which is break down organic materials such as dead leaves.  They do this extremely rapidly, moving nutrients from dead organic materials into the soil quickly.  As a result, plants cannot absorb the nutrients as fast as need and much is lost when water washes it out of the soil.  The burrowing action of worms also functions to compact forest soils, making it more difficult for plants to survive.  While some plants are well adapted to earthworms crawling around through their roots, other plants are extremely sensitive.  Sugar Maples, one of the dominant plants in these northern forests, is extremely sensitive to earthworms. Establishment of maple seedlings where earthworms are present becomes very difficult.  Northern forests with earthworms have far fewer plants than forests without earthworms.  Simply by changing soil and forest floor structure, the earthworm has a huge effect on the overall habitat. 

Fortunately, earthworms have not taken over every single forest in these northern areas.  Also fortunate is the fact that worms only travel about 6 yards a year.  This means, if people quit transporting worms to new areas in the north, populations of worms aren't going to expand much. 

Great Lakes Worm Watch

Life of a Maple Part 3: The Maple Tree and Sunlight

When it comes to soil, Sugar Maples are pretty picky.  When it comes to sunlight however, maples aren't picky at all.  Other trees, such as oaks, prefer to have as much sunlight as possible through out their entire lifespan.  Maples however can do quite well with very low levels of light early on in life.  This is a very fortunate adaptation being the most ideal soils for maples are typically going to be located in the shade of large trees.  Lots of, but not complete, shade aids the germination and early sprouts of maples.  However, maple seedlings will often have stunted growth in very low light situations.  Small seedlings and saplings are capable of surviving many years in the shade of larger trees.  Other sun loving trees such as oaks simply would die due to lack of sunlight.  These small maple trees simply wait until the larger tree dies and is removed by ice storms, wind, or disease.  The wait for an older maple to die can be a long one though being they are capable of living 500 years. 

Once these over-story trees are out of the way, smaller trees that had waited patiently in the shade for years suddenly make a bolt for the sky until becoming a dominant tree in the forest canopy.  This cycle can then repeat itself many times over with younger maples replacing older maples.  This self sustaining process of the Sugar Maple forest will continue unless significant disturbance such as fire or major drought take place.  If disturbance does happen, plants that require more light, such as grasslands or oak forests, will replace the maple trees.  Given time though, and lack of disturbance, after a hundred or more years the maples will replace sun loving trees such as oaks and will again dominate the forest.  This process of one plant community replacing another plant community is called succession.  Maple forests typically are the last stage in succession, which is called the climax plant community. 

Slow growth, long life, and tolerance for shade are what make the maple a climax forest species.  Faster growing trees with shorter lives typically require lots of light and occupy areas after a major disturbance such as fire.  The slow growing maple tolerates the shade and out live these faster short lived species.   Shade tolerance is one of the most important adaptations maples have to being a late successional climax tree.  There are a number of more minor adaptations that aid in the overall shade tolerance of maple.  First off, maples form large thin leaves that gather light very well.  Leaves lack pubescence, or hairiness, which would block light.  These leaves also grow to orient themselves in a manner that helps them gather the most sun light.  Pigments inside of the leaves also are especially adapted to gathering far red light which is abundant in shady environments.  Lastly, maples produce a huge number of leaves in their canopies in order to catch as much light as possible.  Such a great density of leaves are produced by Sugar Maples that the top 10 percent of leaves gather 60 percent of the total sunlight. 

Life of a Maple Part 2: Soil and Roots

A moist maple forest with rich soil.

A Sugar Maple seed doesn't get to choose where and what type of soil it gets to land on.  Typically, where the seed lands is a result of wind direction and strength at the time it falls.  Where ever the seed germinates and begins to grow is where it will spend the rest of its life.  The unfortunate majority will die long before reaching a foot in height.  Often, predators such as deer and squirrels, find the young seedling far to appetizing to pass it by.  Many seedlings will also unfortunately find themselves in soil that is less than ideal.  As far as deciduous forest trees go, the Sugar Maple is quite picky, much like Goldilocks.  The soil can't be too wet or the roots will suffocate as they drown in the water soaked soil.   Neither can the soil be too dry or the roots will dehydrate.  Nor can the soil have too much clay or too much sand.  They soil has to be just right. Even when the soil has just the right texture (meaning the right amounts of clay and sand) and the right amount of water, the soil might not be good enough.  The soil also has to have high levels of nutrients.  Soils with low nitrogen or calcium may prevent healthy growth and longevity of maples.  Even then, maples seem to prefer very deep soils deposited by glaciers over any other type of soil.  The maple is very picky...

The reason the maple is so very picky is because of its roots.  Just like branches of deciduous trees shed their leaves annually, larger roots also shed tiny roots annually and with dry weather.  Maples produce an abundance of these fine roots at very shallow depths, right where the nutrients are highest.  It has been estimated that 60 percent of annual productivity of maples is actually contained within these roots.  This is quite amazing when you consider the great density of leaves maple trees produce annually.  The fact that so much of the tree is in-fact these very sensitive tiny roots makes the whole tree very sensitive to whatever happens on or in the most shallow layers of soil.  Trampling by foot traffic, vehicles, or cattle can damage these roots as well as cause the soil to dry out, killing the roots and potentially killing the whole tree.  If fire burns across the ground, the surface soil will be significantly dried out also potentially killing the roots.  The heat of the fire can also kill the roots very easily.  Pollution, such as acid rain, can change the chemistry of the soil, also killing fine roots and damaging the overall tree.

Fortunately, the maple tree does have some adaptations that help make it at least a little less sensitive to changes in the surface soil.  For one, the overall root system of maples is capable of hydraulically redistributing moisture from deep within the soil to more shallow soils.  The thick shade of maples also helps to prevent evaporation of moisture from the soil.  Also, the fact that maples transpire, or "exhale", large amounts of water vapor while photosynthesizing helps cool the environment and increase humidity.  Fallen leaves are very absorbent and are a very effective mulch that help hold moisture in the soil.  All of this helps moisture to be retained within the soil where it can be utilized by the tree and prevents moisture from evaporating into the environment.  All around, the maple works to keep its environment as moist as possible.

Sugar Maple tree in fall.

Life of a Maple Tree: Part 1 Seed to Sprout

I'll be starting a new series on the blog about the life cycle of the maple tree, specifically the sugar maple.  This is sort of a follow-up to the series on oaks and hickory trees.  Maples are sort of a logical follow-up to the oak-hickory forest being they are later successional species to the oaks and hickories.

Sugar Maple leave

The life of a maple tree begins with the charismatic "whirlybird" seed which fall like helicopters from the mother maple.  Often masses of these seeds will blow off of mature maples and twirl to the ground on windy fall days.  Technically, these "whirlybird" seeds are called samara, which are simple seeds with a flattened papery wing-like portion.  The whirlybird nature of these seeds helps the wind to carry them a long to new locations, often hundreds of yards away.  Then hopefully, the seed will be able to sprout and develop into a new tree.

Once on the ground, the maple seed prefers moist and undisturbed locations, such as in a maple forest or an oak-hickory forest that has not been disturbed by fire.  This is because the maple seed is not well protected.  While the wing portion of the samara is good for transporting the seed with the wind, it doesn't do much else.  The seed requires a moist area, and is easily killed by damage from trampling animals, dehydration, or heat from fire.  Once on the ground though the seed becomes actively searched out for by numerous small animals such as rabbits, squirrels, and mice.  Predation really isn't too much of a problem though, the maple tree typically produces so many seeds that it overwhelms predators.  Predators have plenty to go around and there are still plenty of seeds left over to germinate and sprout. 

Sugar Maple samara seeds.

If not found by seed predators on the ground, the seed than requires the cold of winter in order for it to germinate.  Without cold, the seed will not germinate.  Many species of trees, such as oaks, have a difficult time establishing themselves in soil covered with a thick layer of leaves.  Oaks therefore require the ground to be disturbed by fire so their acorns can sprout and grow.  The maple however, does not have this problem and prefers undisturbed forest ground cover, often thickly covered with dead leaves.  Once germinated, the root easily penetrates through thick moist layers of leaves from the previous year. 

Another oddity of the maple is that it prefers shade.  The maple does not like competition with other small plants such as grasses and shrubs.  It does to quite well though when growing under the canopy of mature trees that shade-out other plants.  In-fact, maple seeds germinate and grow best where there is 50 percent or more shade.  In these areas tiny maple seeds can sprout by the thousands, often leading to a carpet of young maple trees.  The problem though is, once germinated there is so little light in these areas the trees will not grow very large and growth will be stunted.  Again though, the maple is adapted to this situation, being able to survive, but not grow, in minimal light retirements for many years.  The tiny stunted tree simply waits until older larger trees casting shade on the forest floor die.  Once these larger trees die, the tiny maple tree grows rapidly in the new sunlight. 

During the potentially long period of time that a maple seedling remains a small stunted tree it is important that the forest remains undisturbed.  Fire and drought both will easily kill these seedlings.  Predators, such as deer, also heavily browse on "carpets" of small maple seedlings.  Usually though, plenty of seedlings survive predation with drought and fire being the big killers. 

Life of a Cactus Part 10: Nurse Plants

The pulp within a cactus fruit contains hundreds to thousands of seeds.  Unfortunately, very few of these seeds will ever germinate, and probably less than 0.1 percent of these seed will ever grow to mature plants.   Life is just too dangerous and for the seed and young plants.  The first problem a cactus seed faces is also a blessing.  The succulent flesh of a cactus fruit is like a magnet during the bitterly dry and hot summer.  Birds and animals gorge themselves on these fruits as a rich source of moisture and nutrients.  As they eat the fruit though, many, if not most of the seeds are also eaten.  This isn't such a bad thing, as long as the seeds are not crushed by chewing.  The seeds are especially adapted to remaining intact and passing directly through the digestive tract unharmed.  With most cactus fruit being brightly colored and located high on the plant, these fruits are especially enticing to birds, which may be the only organisms capable of reaching the fruits on taller cacti.  For example, the saguaro cactus holds its fruits tens of feet off of the ground, only allowing birds to access it.  Being birds do not chew food, instead swallowing it whole by the beak-full, most of the seeds can pass through the digestive tract unharmed and be deposited in their fecal matter.  Kind of a disgusting start to life but true never-the-less. 

Young Saguaro Cactus growing under the canopy of a Palo Verde.

Being birds of course frequently perch and sleep in shrubs and trees, most of their fecal matter, and therefore cactus seeds, will be deposited below.  This is the ideal environment for a cactus seed to germinate and grow in.  The shrub or tree provides shade which creates a slightly cooler and moister environment for the seed to germinate and grow in, something much needed in the desert.  The shrub or tree also provides cover and protection from predators which might eat recently germinated seeds.  Soil also is slightly more rich in these locations also.  This environment under the shrub or tree is termed a microenvironment and the plant that makes it is called a nurse plant.  Of course, the nurse plant is termed such because it helps, or nurses, young plants such as cacti to maturity in the microenvironment they create.  A microenvironment is a small area, such as under a tree canopy, that has slightly different conditions than the surrounding environment.  Within the Sonoran Desert Triangle-Leaf Bursage is the most important nurse plant.  Very few plants are able to grow without the nursing aid of a Bursage microenvironment.  This is sort of odd considering Bursage is such a small desert shrub, usually only reaching 20 or so inches in height.  Bursage is however one of the few plants capable of establishing itself without a nurse plant and is extremely abundant across the desert.  Other plants such as Palo Verde trees are well known nurse plants but not as important as Bursage.  This probably is because Palo Verde can't become established without a nurse plant and are not as common as Bursage.  Interestingly, the most common nurse plant for Palo Verde is also Triangle-Leaf Bursage.