Merry Christmas and Happy New Year

I'm taking a short break from the blog over the holidays but will be back in January!

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...

December Ephemeral Drainage Flow

A dry wash the morning after a flash flood came though.

The mid-December rain is the most reliable rainfall we receive here in the Sonoran Desert.  This rainstorm is almost like clockwork.  Every December, usually around the 15th or so, a strong Pacific frontal storm system brings rainfall in from the northwest.  One-half to one inch of rain pretty much falls across the entire desert with higher totals in the mountains.  Of the past ten Decembers, only one failed to produce any rainfall and that was during one of the driest winters on record in Arizona.  This year was picture perfect with one-half to one inch of rain falling in the Sonoran Desert between December 13th and 15th.  With this rain being almost like clockwork, the flow of the normally dry washes also flow during this rain almost like clockwork.  This year was a little odd in that the rain was spread out over a three day period making flows a little weaker than normal.  Typically, dry washes require a significant amount of rain over a short period of time in order to generate enough runoff to supply a flow.  A lot of drainages did flow at least a little though. 

Of course, a lot of rain over a short period of time helps these washes to flow in the desert, but there are other factors involved also.  Geology, or geomorphology, are probably the most important factors in determining flow.  Geomorphology is simply a scientific term that describes how landforms came about and how they function.  One of the functions of geology and geomorphology in the landscape is to determine how and where water flows.  For example, shallow unbroken bedrock is going to prevent water from seeping down into the soil and therefore will result in greater amounts of runoff.  Type of soil also matters in the amount of runoff produced.  Rain seeps very slowly into clay soils so a lot of runoff can be generated.  Sandy soils however can quickly absorb a lot of rain so not much will runoff.  Number of rocks also makes a difference.  Soils with fewer rocks have more runoff than soils with more rocks.  Rocks on a soil surface slow the speed of runoff and with slow speeds of runoff the water has more time to be absorbed into the soil.  Size of the dry wash also makes a difference with smaller washes flowing more frequently than larger washes.  However, larger washes tend to run longer than small washes when they do flow.  Larger washes simply need a lot more water to flow. Depending on the combination of these factors some washes will flow a few times annually while others will only flow a few times a decade.

All of these things factors also determine what lives where along a dry wash.  Flow is normally very short in duration in a wash.  This is simply because flowing water quickly is lost as it is absorbed into the sediments of the stream bed.  Though flowing water is lost, the water is not entirely lost.  Water is stored in these sediments for long periods of time after surface flow ends.  Depending on the depth of this moisture and the depth of the sediments differing plants will occupy the area.  Typically, deep sediments with relatively frequent flows will be occupied by blue palo verde and desert willow.  Areas of fewer or shorter flows typically have yellow palo verde.  Other plants such as acacia's, ironwood, wolfberry, and mesquites can be somewhere in-between. 

Fall Leaves in a Sonoran Desert Riparian Zone

A Sonoran Desert riparian area in fall along Cottonwood Creek.

The desert is most definitely not known for spectacular fall colors.  Fall colors do however, find their place along some of the wetter desert water courses.  If perennial water sources are available, even if it is hidden below ground a short distance, the roots of large deciduous trees will find there way to it.  Sycamores, cottonwoods, and willows are all relatively common along streams and washes with perennial sources of water.  Even Arizona walnut and ash trees can be found in some of the more stable riparian zones.  These trees do not display the brilliant hues of red and orange common to eastern forests but do show off bright yellows that are in stark contrast to the dried out browns and greens of the desert.    Desert fall leaves are quite a rarity and are quite unique.  Typically, perennial water sources are considered perched water tables.  A perched water table simply is water that accumulated above the surrounding water sources, most often a result of bedrock that prevents water from penetrating deeper into the soil and out of reach of plant roots.

A recent hike I took demonstrated this concept extremely well.  The hike was along Cottonwood Creek near Lake Pleasant north west of Phoenix.  The majority of this hike is along Cottonwood Creek, which really isn't much of a creek considering water only flows in this creek a few hours every year.  The rest of the year the wash remains mostly dry, except for a few locations.  Nearly all washes in the desert are called dry washes, and for good reason: they are completely bone dry the majority of the year.  A few washes, such as Cottonwood Creek are fortunate enough to have areas that always remain wet.  Cottonwood Creek owes this moisture to its underlying geology.  First off, the creek bed lays at the base of two small bajadas between two small mountain ranges.  One bajada lays to the north of the creek bed and one to the south.  These bajadas and bedrock of the mountains are relatively steep and provide ample runoff to Cottonwood creek so it will run during periods of heavy rainfall.  Moisture is quickly lost into the deep sediments of the bajada and placed out of reach of deciduous tree roots.  In areas where bedrock are shallow though, moisture cannot penetrate deeply and remains closer to the surface within reach of plant roots.  Bedrock can also push water flowing underground towards the surface.  At these locations large deciduous trees take advantage of the shallow moisture and can in a few places form small but beautiful wooded areas.

Wildlife may not be obvious in these small wooded areas, but if you look at the ground you are sure to see evidence of animals.  Javelina and mule deer heavily utilize these small areas and their hoof prints are normally abundant.  In some area, such as along Cottonwood Creek, wild donkey's are also abundant and heavily utilize these areas.  The abundance of shade, food, water, and cooler conditions during hot dry summers gives great value to these areas for every creature.

Preventing Illness This Winter

Its the season for getting sick... A part from the normal concerns of the holiday season, we have the additional concerns of catching a cold or the flu this time of year.  Apparently, this years strain of flu is especially bad.  Specifically, the flu virus is H3N2 and has increased the number of hospitalizations for the flu compared to normal flu seasons.  The thing I always want to know this time of year is how I can prevent myself from getting sick.  There are a number of things that can be done to help prevent illness.  Of course we always hear to get vaccinated and to wash your hands.  But in addition to that, studies have shown reducing stress, meditation, getting enough sleep, exercising, drinking lots of fluids, maintaining a healthy weight and limiting sugar intake all help strengthen your immunity.  Unfortunately, this may be the worst time of year for getting enough sleep, reducing stress, and limiting sugar intake.  So I guess we'll all have to do our best.  Other interesting things I found were that the ideal house temperature for reducing illness is 68 to 72 degrees with about 50% humidity.  Viruses can survive longer inside with the lower indoor humidity this time of year, so having a humidifier is beneficial to your health.  There is also a lot of various information out there on how much exercise is ideal for boosting immunity.  From what I have read and sort of averaging a bunch of reports and research together, exercising thirty to sixty minutes, three to five times a week boosts the immunity the most. 

The Biology of Bread Making

The process of making bread is an extremely biological process.  Good bread bakers are experts at controlling the biological processes involved in making delicious bread, even if they don't know it.  There are two major biological components to bread, first is the wheat flour and specifically gluten, and secondly the yeast.  A typical bread recipe is very simple and includes water, sugar, salt, wheat flour, and yeast.  All of these ingredients work together to create an environment for the yeast that creates bread.  I will explain each of these components and discuss how they can create the ideal bread making environment.

First we will talk about sugar.  Sugar is very easy for yeast to consume and therefore helps the dry yeast off to a quick start.  This helps the yeast to quickly start growing and reproducing, causing the bread to rise.  Yeast also can consume the carbohydrates in the wheat flour, but these are harder to consume.  Depending on how much sugar is added, the yeast will normally consume all of the sugar in the dough.

Water in the bread making process is not extremely interesting.  It is of course a requirement for all of life and without it the bread would never form.  In bread making tough it is important to balance the amount of water to the amount of flour to get the right consistency in the dough.

While sugar helps speed-up the reproduction and function of yeast, salt slows it down.  By balancing the salt and sugar in the dough recipe we can balance the growth of the yeast, not too fast and not too slow.  Without salt, the dough would rise too quickly and collapse.  With too much salt though the bread would rise extremely slow. 

Wheat flour of course is what actually composes the bread.  I say wheat flour specifically because wheat is the only type of flour that contains the protein gluten.  Without gluten the flour would not rise into a spongy loaf of bread but rather would turn into a dense heavy mass of cooked flour.  Gluten is a long sticky molecule that sticks to other gluten molecules.  This allows the yeast to form air bubbles in the dough, making it rise.   Gluten molecules stick together, making the flour in the dough to stick to itself so it can rise.  Without gluten, bubbles couldn't form and the dough would not stick together and the dough would not rise.  Flour also provides carbohydrates for the yeast to grow and function.

Lastly, yeast produces carbon dioxide that helps form bubbles in the dough, making it rise.  As yeast consumes sugars and carbohydrates it releases carbon dioxide.  Without the carbon dioxide produced by the yeast, the dough would not rise.  Yeast functions best at warmer temperatures so more time is needed for bread to rise when temperatures are lower.  When you finally bake your bread, the high temperatures of the oven actually kill the yeast and solidify the gluten and dough structure.   Baking ends the biological processes of bread making so it is ready to eat.

A lot more can be said about the origin of yeast and gluten as we find them in our breads today.  But the above are the essentials of the biology making bread.  Knowing these things can greatly aid your ability to come up with your own recipes and make the perfect bread.  Using the above, you can also come up with your own scientific process or experimentation in bread making by varying water, sugar, salt, and yeast amounts.

Science Education Crisis

Looking around the world today, its easy to see a significant number of science related problems. Climate change, ocean acidification, resource depletion, overpopulation, invasive species and so on, the list is depressingly long. On the positive side though, there are relatively straight forward solutions to a lot of these problems. Straight forward doesn't mean simple to implement through. For example, renewable energy has potential to easily offset burning of fossil fuels and therefore providing solutions to climate change, ocean acidification and resource depletion. Implementation of renewable energy though very plausible, will take a lot of work and changing of peoples mindsets. Probably the largest hurdle in this is simply education of the general public. I have worked in science education and biological research for about a decade now and have seen huge discrepancies between the two. Researchers with all their vast knowledge of extremely important scientific information that has the potential to help humanity simply don't communicate their concepts well to the masses. Scientists also have isolated themselves from the masses with the general belief that most people just can't understand science. The average high school or even college biology 101 textbook doesn't really paint the big picture for students to learn, but instead focuses on overly compartmentalized concepts. The average high school biology teacher's knowledge of the subject also seems quite limited to these overly compartmentalized concepts. As a result, the masses really don't get what is going on with subjects pertaining to science. I personally am of the belief that even though science is hard to understand, the average person is able to understand at least some of the more complex concepts. Students must be taught by teachers who know the concepts in the first place, and in a way that connects students to the bigger picture. Regardless of what anyone says, science is extremely interesting and people who say science is boring simply have a poor science education. Science is so diverse it can literally engage every field of interest possible, there is absolutely no room for boring with this great diversity. I'm not saying everyone should become scientists, I am simply saying that science should engage everyone in whatever profession they choose. Currently, science is highly compartmentalized in our society with the educationally elite. This should not be so and is highly damaging to our society. The educationally elite scientist is absolutely necessary to science but I would suggest needs to greatly improve communication of their research with the masses. Improving scientific communication and education with the average non-scientist is the goal of the Practical Biology blog. Hopefully I have begun to do this. I feel there is a lot more that can be done and a lot more depth that can be given to non-scientists, or even scientists, through this blog. Knowledge is power and scientific knowledge has potential to greatly benefit individuals as well as society.