White Tank Mountains Goat Camp Trail

Desert grassland with mainly tobosa grass located at the top of the White Tank Mountains west of Phoenix, Arizona.

Goat Camp Trail in the White Tank Mountains west of Phoenix is the longest trail in the park.  It can be done as a 13 mile loop along with the Mesquite Canyon and Bajada trails or a 12 mile hike from trail head to end and back.  The trail head is just past the park entrance on Black Canyon Road.  The first mile and a half of this trail is pretty easy starting at 1600 feet in elevation and hiking up a bajada.  This bajada is fairly interesting.  It has been highly disturbed by some major flood events along the dry washes that come out of the mountain canyons.  This disturbance is evident increasingly as you hike towards the mountains by the presence of large boulders laying on the surface.  Normally, these boulders would be sitting lower in the sediments of the bajada being at least partially buried in the dirt.  Large floods however coming from the canyons washed away a lot of these sediments but were not strong enough to wash away the larger and heavier rocks.  So the rocks remained in place while the finer textured sediments washed downslope.  These unburied boulders become increasingly common upslope where the flood, or floods, were more powerful.  These floods resulted in increasingly variable disturbed soil conditions higher up on the bajada and closer to the mountain.  As a result of the more variable soil conditions plant diversity also increases up slope.  Sections of undisturbed soils typically have triangle leaf bursage while the disturbed sections brittle brush.  Other species such as palo verde and jojoba also seem to like the flood disturbed soils.

After a mile and a half or so, the trail begins to head up the mountain.  This trail has an elevation gain of about 1700 feet, topping out around 3300 feet.  With the elevational gain, average annual temperature decreases several degrees and rainfall increases several inches.  At the mountain base, rainfall averages about 8 inches annually.  At the higher elevations rainfall probably averages around 14 inches annually.  There is a rain gage at the top of the White Tanks but apparently gusty winds around the peak prevent it from collecting rain properly, so it is difficult to get an exact measurement of rainfall at the peak.  Regardless, the vegetation tells us that rainfall is significantly higher and temperatures slightly lower.  In the past decade or so I have seen snowfall above 3000 feet in the White Tanks only one time and never below that level.  The lower temperatures, specifically lower freezing temperatures in winter, make conditions less ideal for cacti such as the saguaro.  Saguaros are not able to survive freezing tempertures for longer than 24 hours.  While the saguaro does grow near the peak it is quite rare in comparison to lower elevations.  This is at least partially due to the increase in the amount of time freezing temperatures occur at the higher elevations.

I think there may be another, possibly better, explanation for the decrease in cacti towards the top of the White Tanks though.  Around 3000 feet the vegetation strongly shifts towards a desert grassland dense with tobosa grass.  Tobosa increases because of the increased rainfall and because it can survive the freezing temperatures quite easily.  Dense tobosa grass is possible out competing the cacti at these higher elevations.  Another indicator of a problem for cacti at these higher elevations is the presence of charcoal.  Obviously charcoal indicates fire has been present in the area at sometime in the past and cacti in general do not survive fire very well.  Grass, such as tobosa, however, are very flammable and actually encourage fire to some extent.  Grass, unlike cacti, are very adapted to fire through.  While I have never seen or heard of a grass fire at the top of the White Tanks, the charcoal is evidence that it has happened at some time in the past.  Even if fire happens only once every few decades, that is enough to severely limit the population of cacti in the area.

A few other plants that are relatively common at the higher elevations include desert agave and crucifixion thorn.  Most of the desert agaves are pretty small and almost all appear to be clones that have grown from root sprouts of older plants.

Crucifixion thorn.

Desert Agave

Desert Canyon: Ford Canyon Trail White Tank Mountains Part 2

Higher elevation (around 3,000 feet) in the White Tank Mountains west of Phoenix.  Here grasses are a lot more common and cacti, trees and shrubs a lot more rare.

Towards the middle of the canyon eventually a small dam will be reached.  Personally I really wonder why this dam was built.  I can guess that it was built by ranchers to form a water hole for their thirsty cattle.  But really, how in the world would they ever have carried so much cement up into this rugged and remote section of the canyon?  Beyond that, the dam doesn’t hold much water at all.  It is extremely effective at holding sand though and the entire area behind the dam is completely filled with it.  All that work hauling cement up into a rugged and remote canyon to build a dam that doesn’t hold water but rather holds a lot of sand.  Talk about a disappointing work project.  After the dam however, the wash bed becomes a lot less rugged and more sandy, with much of the trail going directly through the wash.  Here the wash becomes much more wash-like and less canyon like.  The banks are lined with mesquites, catclaw acacias, wolfberry bushes, grasses, canyon ragweed, and the invasive tamarisk tree.  All indicators of increased water availability in the wash due to infrequent flash floods.  Fortunately, the tamarisk doesn’t seem to be causing much of a problem here. 

When hiking in the sandy area of the wash above the dam, there is a remarkable increase in the grasses along the hillsides.  Tobosa, three-awn, and big-gallete are the most common grasses.  All of these grasses require the slightly greater amount of precipitation and slightly cooler temperatures present at this elevation of around 3,000 plus feet.  The grasses are most abundant lower on the hillslopes where soil is slightly more developed and holds water better.  After leaving the wash the trail continues through several areas with high amounts of grass cover, which is a nice change from the ubiquitous cactus and shrub studded landscape below this elevation.  Continuing upslope however, the soil becomes increasingly rocky with brittlebush becoming the dominate plant.  Brittlebush has a strong preference for rocky, unstable, and dry soils more typical higher up on mountain or hillsides.  Also, looking closely along the trail you may find some charred stumps.  This is a result of infrequent grass fires at this higher elevation.  At lower elevations it is pretty rare to find charred woody materials due to sparse vegetation that is not able to carry fire far.  The greater amount of grass cover at higher elevations though more easily carries fire.  Fire generally promotes more grasses to grow and kills shrubs, trees, and cacti.  At least partially for this reason cacti and palo verde are far less common at these higher elevations.  Wire lettuce, buckwheat, brittlebush, and globe mallow also are common at these elevations and seem to be able to colonize bare ground quickly after a fire.

After a few miles of hiking through desert grasslands of the upper elevations of the White Tanks
the trail will come to an end at the Mesquite Canyon Trail and Goat Camp Trail.  I currently am 105 miles towards my goal of 150 miles in 2012.  Hopefully I will be able to reach 150 miles in the next two months or so.  Then maybe I'll extend my goal out another 150 miles.  Due to my schedule being quite busy these last few weeks I haven't done much hiking.  And I have definitely missed it.  The health and relaxation benefits become quite clear after missing a few weeks as I become a little more stressed out and feeling a little less in shape.  I am planning a lot of hiking in the near future though.

Desert Canyon: Ford Canyon Trail White Tank Mountains

Ford Canyon Trail is my favorite hike in the White Tank Mountains.  The rugged terrain, diversity of landscapes, and mixture of easy and challenging sections makes this hike worth repeating.  For my recent hike I took a loop from the parks Ramada Picnic and parking area starting with the Waddell Trail, to the Ford Canyon Trail, then to the Willow Canyon, and finally returning to the parking lot by the Mesquite Canyon Trail.  Entire length is just over nine miles.  For this particular post I will be highlighting just the Ford Canyon section starting at Waddell Trail and ending at Mesquite Canyon Trail.

The trail approaching the canyon ascends a gently sloping bajada.  This bajada is beautifully surrounded by mountains to the north, south and west, opening up to the basin desert below.  Millenniums of decaying granite in the mountains have been carried down through the Ford Canyon, depositing a composite of alluvial fans, and forming the bajada we can see today.  This particular bajada appears to have been extremely stable being the surface is relatively flat and shallow rooted triangle-leaf bursage and cacti indicate a layer of caliche just below the surface.  The area also, though not grazed for three decades or more, still shows evidence of trampling by cattle.  This trampling is evidenced by the large and nearly barren areas where the soil is too compacted to support plant life.  After a relatively short hike up this bajada you enter the canyon.

Saguaro Cactus along the Ford Canyon Trail.

Ford Canyon is the roughest hike in the entire White Tank’s park.  But its rugged nature is exactly what makes it so appealing.  Within a short distance into the canyon you will begin hiking and even climbing over house sized blocks of granite.  Large sections of the canyon have nearly vertical drops of tens of feet just off the edge of the trail.  The wash bed in this section of the canyon is not nice, sandy, and smooth.  It also is extremely rough with lots of high drop-offs and large sections of smoothly worn granite.  The ruggedness of this canyon is witness of the decay of this mountain.  In extremely ancient times, all of these blocks of granite, the house sized blocks down to the sand sized fragments, were all part of one massive unbroken mountain-sized block of granite.  Pressure from movement of the surrounding geology began to crack and break this block.  Very likely Ford Canyon began as one or many small but long cracks in this mountain sized block of granite.  Extreme desert heat caused further cracking and breaking down of the rock enlarging the initial cracks.  Water flowing into and through the crack or cracks eroded and dissolved the rock, enlarging it further.  Plant roots working their way through smaller surrounding cracks continued to enlarge the initial crack.  All of these processes continue their work to this day, and continue to form the present day Ford Canyon. 

Canyon in the White Tank Mountains.

The many large drop-offs in the canyon means many large waterfalls, which unfortunately only flow for a few hours a year and only after large rainfall events.  I only hiked through this canyon once, during a heavy rainfall with the wash flowing and water dropping over the many falls.  Unfortunately, but dramatically, much of the canyon was shrouded in fog so I could only see portions of a few of the waterfalls.  The combination of rain, fog, and sound of flowing water through the canyon is a desert rarity.  Typically, the desert is peacefully quiet with only the sound of occasional calling birds, giving it a strong sense of solitude.  Further up in the canyon there are many holes in the unbroken granite bedrock where water accumulates and can hold many months after rain.  When the rest of the desert is dry after months without rain these water holes will often still hold water and become magnets in the landscape for wildlife.  In a recent hike I found and abundance of water in many different holes, even though there had been no rain for a month.  The surrounding landscape was nearly bone dry and the high density of mule deer and javelina hoof prints around these holes attests to their importance to these animals.  

Part 2 will be continued on Monday.  So far I have hiked 101 miles this year.  Unfortunately, I haven't added any miles to this over the past three weeks due to a busy schedule.  Hopefully this weekend I will be able to put in a few miles though.  

White Tank Mountains: Mesquite Canyon Trail Part 2

Barrel cacti.

The trail continues upslope until it comes to a fork in an area of the mountain that broadens and levels out.  Here you have the choice to head to the right on the Willow Canyon Trail or continue to the left on the Mesquite Canyon Trail.  For our purposes we will continue on the Mesquite Canyon Trail.  At this point the elevation has increased to about 2,400 feet and as a result temperature and precipitation also increase in this area.  Average annual temperature is about 2 degrees cooler at this elevation and precipitation about 2 inches more.  At this elevation the Sonoran Desert begins to transition into desert grasslands.  Cooler temperatures prevent cacti from establishing and increased precipitation begins favoring grasses.  In this flatter basin like area of the mountains there still are a lot of Saguaro cacti.  Something interesting I noticed was that Saguaros were smaller and had fewer arms here than Saguaros at the base of the mountain.  While this may indicate the Saguaro population grows slower here, I suspect it is because they are actually younger in age.  This means the population is much healthier and more actively reproducing at this higher elevation.

Saguaro Cacti along the Mesquite Canyon Trail.

Continuing on the trail, by the time the trail hits about 3,000 feet, close to the Ford Canyon Trail, Saguaros are extremely rare.  The Ford Canyon Trail reaches slightly over 3,000 feet, here average temperature has decreased to about 70 degrees (4 degrees cooler than the base of the mountain) and precipitation increased to about 11 inches (about 3 inches greater than the mountain base).  At this elevation there are far more grasses.  Also, if you look closely at the ground often charred sticks and stumps can be found.  Anytime there is an increase in grasses there is also an increase in the presence of fire.  Charred sticks and stumps indicate the historical presence of fire at this elevation.  It seems that charred wood increases right around 3,000 feet near and along the Ford Canyon trail.  With fire and freezing temperatures more frequent at this elevation, cacti, and especially saguaros, are much rarer.

Hiking through this higher elevation area there are two main vegetation types, areas dominated by brittle  bush and areas dominated by grass.  Brittle bush generally occupies ridge tops where the soil is extremely rocky and loose.  These areas are extremely well drained and therefore very dry.  Lower on the hill or mountain sides through soil becomes more stable and better developed.  Red coloration of this soil is an indicator of its stability and anywhere there is reddish soil there is an abundance of grasses.  Likely, water runs off higher slopes where brittle bush is present into areas where grass dominates, making grass dominated areas generally wetter.  And when I say wetter I mean that in a desert sense, where wet is still very dry.  These grasses are quite interesting, they are almost bushy and semi-woody.  Most of the year they are a drab tan color but in spring after winter rains and late summer after monsoon storms they will green up considerably.  The higher elevations of the White Tanks are blanketed with rolling hill and mountainsides of these two or three foot high grasses; quite a different sight from the desert shrubs and cacti of lower elevations.  There are three different grasses that dominate here: three-awn, tobosa, and big galleta.  Tobosa and big galleta look almost identical and are almost bush like.  Three-awn is more grassy standing more up-right.

Desert grasslands found at the upper elevations of the White Tank Mountains.

Taking the Willow Canyon Trail where it intersects with the Ford Canyon Trail, will return back to Mesquite Canyon trail.  From here it is a generally down slope hike.  With the lower elevations down slope and corresponding lower rainfall and higher annual temperatures, the desert vegetation returns. 

This concludes the Mesquite Canyon-Ford Canyon-Willow Canyon trail loop in the White Tank Mountain Park.  Currently I am 59 miles towards my goal of 150 miles of hiking this year.  I have two other nature hike posts ready to go for the near future.  I am wanting to get all my hiking in prior to the scorching heat of summer that starts in June.  I am really enjoying this hiking goal.  So far I can tell there have been huge benefits in the way I feel and the strength of my body.  When I started an eight mile hike would leave me tired and soar.  Now though, an eight mile hike is easy.  In the very near future I will be doing a 13 mile hike, hopefully my body will hold-up without problem.

White Tank Mountains: Mesquite Canyon Trail Part 1

Saguaros along the Mesquite Canyon Trail.

The Mesquite Canyon Trail loop is the first hike into the mountains to be posted here and will introduce us to some of the common aspects of desert mountain ecology.  The White Tank Mountains are a small isolated range in the Sonoran Desert just west of Phoenix.  At the start of the hike at the mountain base the elevation is about 1,500 feet.  Peak elevation in the White Tanks is just above 4,000 feet but the peak elevation for this trail is around 3,000 feet along the Ford Canyon Trail portion of this loop.  The trail begins on the bajada which was deposited by Mesquite Canyon which the trail continues into.  This first section of trail through the canyon is quite steep as elevation increase about 500 feet in the first mile or so.  This is the roughest portion of the hike and after that it smooths out.  Mesquite Canyon Trail continues for a total of 3.1 miles until it reaches the Ford Canyon trail for which you take for 0.7 miles.  At that point you return to Mesquite Canyon via the Willow Canyon Trail which is 1.6 miles.  From there you return to the mid-point of the Mesquite Canyon Trail and continue downslope the way you came up through the canyon.  Total round trip is 8.1 miles. 

Starting at the ramada parking lot, the trail begins up a flat bajada gently sloping up towards the mountains.  This bajada was deposited by the canyon the trail continues into.  All of the sediments of this bajada were once carried by erosion off the mountain sides and by flashfloods through Mesquite Canyon and deposited outside the mountain to for an alluvial fan of the bajada.  Hiking into the canyon you can begin to see this bajada forming process.  The bajada begins as giant boulders from the mountain that are cracked and broken into increasingly small pieces until they form sand.  Most of the White Tanks are what is considered White Tanks Granite which forms a lot of sandy sediment when broken down.  Extreme desert heat, water, and plants all work together to break down the large rocks into sand.  As the rocks break down they are carried downslope and out of the canyon through the wash during flashfloods until they are deposited in an alluvial fan somewhere at the end of a wash.  Several alluvial fans deposited this way form a bajada.

At first in the canyon the trail continues on a north facing slope.  Looking closely, the plants are mostly Brittle Bush, Globe Mallow, and Jojoba, there is a peculiar absence of cacti.  Looking across the canyon to the south facing slope there are a lot more cacti and Palo Verde along with Brittle Bush.  Why the difference?  Both sides have the same granitic rocks and about the same soils so rocks or soil can’t explain the difference.  The south facing slope however, is far more exposed to the intense desert sun and therefore is significantly warmer and dryer than the north facing slope.  It probably is too cold for cacti to survive on the north facing slope and jojoba likely prefer the greater moisture content there.  North facing slope plants therefore likely can tolerate the cooler temperatures of that slope and are supported by the greater amount of moisture there.  South facing slope plants likely need the heat to survive and are able to tolerate the lack of moisture.  Also, looking closely at the soil you will notice there is an abundance of mosses, lichens, and other very low ground cover on the north facing slope.  This low ground cover is known as cryptobiotic soil crusts and again is a result of the greater amount of moisture on that slope.  The south facing slope with its lack of water due to greater sun exposure results in a near absence of cryptobiotic soil crusts.

Ferns that sprout from cryptobiotic soil crusts after rain.

Heading up the mountain, the trail climbs over a ridge top and continues along the side of a second canyon.  Here the trail levels off significantly and after a little ways the wash bed of this canyon can clearly be seen.  The wash bed is directly cut into the mountains granite.  It has been eroded and polished smooth by millenniums of sand washing over it and wearing it down.  The eroded smooth granite appears almost white in coloration and is full of small holes, known as tanks.  After rainfall and flash floods moving through the canyon these tanks fill with water.  On my recent hike all of the tanks were full of water due to rainfall a month prior.  These tanks, carved in whitish colored granite, are where the White Tank Mountains gain their name.  These tanks also are an amazing asset to the local wildlife being they hold water for months after rain falls.  Without these tanks there would be far fewer mule deer and mountain lions in the White Tanks. (Yes, it’s true, there is a healthy mountain lion population in the White Tanks.  So watch out!)

Teddy Bear Cholla Cactus: White Tank Mountains Ironwood Trail

Three species of cactus along the Ironwood Trail.  Hedgehog cactus lower left, barrel cactus lower right, and teddy bear cholla middle.

The Ironwood Trail is only a 0.9 mile easy hike across a flat bajada, but as for viewing cacti it is pretty good.  When I say viewing cacti, I specifically have in mind Teddy Bear Cholla, and the size of these cacti along this trail, along with the size of this population is rather remarkable.  Typically I would say Teddy Bear Chollas reach about three to four feet in height.  Here however, the stand appears significantly older and there is a sizable population over five feet.  As anyone who has been around Teddy Bear Chollas for more than five minutes knows, these cacti are nice to look at but only at a distance.  And their nasty nature is one of the major reasons why these cacti are so abundant along this trail.

When looking at a Teddy Bear Cholla at a distance it defiantly gives the appearance of a nice fuzzy teddy bear.  The huge density of large spines creates this deceptive appearance and often give the cactus a nice golden orah in the sun.  If you examine one of the joints of this cholla up-close you will notice the spines are so dense it is impossible to touch any green portions.  Using a microscope you would also notice that the spines have many fishhook like barbs on them.  These spines and barbs are what give this cactus its nasty reputation.  The density of spines makes them impossible to avoid and the barbs make the spines difficult to remove, and why you will want to stay far away.  I have had two occasions where I accidently had joints of this cactus firmly lodged in my leg as a result of hiking too close.  The difficulty and pain of removing them I will not soon forget.  A day of two after this, a huge bruise developed where they were lodged.  I have also seen a few dogs get joints lodged in their feet, the resulting yelping and whining was unbelievable.  So stay far away!

Teddy bear cholla cacti.  

This nasty nature of this cactus is the exact reason why it is so abundant on this trail.  You would expect all plants to reproduce through seed, but not the Teddy Bear Cholla.  This cholla does produce seeds but typically none are viable.  Quite a weird problem for any plant to have.  There isn’t even much emphasis by this plant to produce viable seeds.  The cactus doesn’t produce many flowers at all.  Flowers that are produced are green and do not attract much attention.  This problem is easily overcome by the cactus hitching a ride on some unfortunate animal passing by.

As you may know, cacti have the ability to root into soil from nearly any green fleshy portion of their stems, pads , or joints.  Teddy Bear Chollas are especially good at this.  First of all, their joints are loosely attached to the plant.  I frequently see joints simply falling off even with the slightest disturbance or breeze.  Once on the ground these joints can root into the soil and develop into another plant.  Secondly, the spines are extremely sharp easily sticking into the flesh of any animal that passes by and the barbed spines hold the joint in the flesh making it difficult to remove.  When the joint sticks into an animal, the animal then transports it, albeit unwillingly, to another location.  The joint will eventually fall off and once on the ground can root itself and grow into a new plant.  This cholla seems to prefer  soils with caliche but overall they are not really picky and can grow in some of the worst soils were no other plants will grow.

This easily detachable, easily carried, easily rooted ability of the cholla makes it extremely widespread and why it is so abundant on the White Tank Mountains Ironwood Trail.  Prior to the 1980’s the White Tanks were grazed and I would guess the flat area around Ironwood Trail had an especially high concentration of grazing.  As a result cattle frequently bumped into and carried around cholla joints to be deposited elsewhere.  This caused a huge increase in the Teddy Bear Cholla population in this area and the population remains to this day.  Even today, humans, deer, packrats, and other animals continue to transport cholla joints around.  I am sure this is at a much slower rate than the cows used to do though. 

Oh-ya, there are also quite a few Ironwood trees on the Ironwood Trail, as the name implies.  Their presence though is dwarfed by all the Teddy Bear Chollas.  As for my 2012 New Years resolution of hiking 150 miles and blogging nature tours I am currently at 22 miles.  At this rate I will be done before June!

White Tank Mountains Bajada Trail Nature Hike

In our last post we discussed hiking the South Trail in the White Tank Mountains.  Now we'll move on toward a short section of the Goat Camp Trail and finally onto the Bajada Trail.  The end of South Trail and this section of Goat Camp Trail is quite interesting for those who like to examine landscape patterns...

Most of the South Trail is rather straight and smooth, but close to Goat Camp Trail is sort of dips down a little and you will notice the surface becoming a lot more rocky and rugged.  This is the second alluvial fan in the bajada.  Typically this type of surface is closer to the mountain then the previous surface we discussed, so this bajada is sort of upside down.  I suspect this odd configuration of alluvial fans is a result of this second alluvial fan resulting from a large avalanche or debris flow that came out of Goat Camp Canyon.  The abundance of disorganized rocks and rugged surface could be in indication of an ancient avalanche.  The dry wash at the beginning of the trail also is responsible for eroding away the smaller sediments and leaving behind the heavier rocks and a rugged surface.  The major plant cover is brittle bush which prefers rocky and often unstable soil surfaces such as this one.  Palo verde and jojoba also seem to like these soil conditions.  There are also a decent number of cacti present and a few bursage in patches, indicating there is likely some caliche in the soil. 

This rocky and rugged soil alluvial fan surface is more typical higher upslope.

After hiking through the rocky and rugged area and heading uphill slightly on the Bajada Trail from Goat Camp Trail, the trail returns to the same alluvial fan most of the South Trail covered.  So same soil conditions and same plants as most of the South Trail.  But here I want to point out the abundance of saguaro cacti, the icon of the Sonoran Desert.  Saguaros are more abundant here than just about any other area west of Phoenix.  The reason for this is, as mentioned before, the soil conditions and abundance of triangle-leaf bursage.  In addition to that, this area receives about nine inches of rain annually and is relatively free of freezing temperatures.  In areas east and north of Phoenix there are many populations of saguaros that are denser, as a result of greater rainfall, upwards to about 12 inches annually.  These higher rainfall areas are also higher elevation and therefore more prone to freezing which can damage saguaros by causing their arms to droop towards the ground.  Very few saguaros in this area have drooping arms in the area of these trails due to the lack of freezing temperatures.  There are a few though.  Nearly all of the Saguaros in this area are mid to older aged, you can tell the age of a saguaro simply by its height and presence of arms.  The taller a saguaro is the older it is, and more arms usually indicates older age also.  There are not a lot of young saguaros, which tells us there isn’t much reproduction going on, and if reproduction doesn’t increase in the next 50 or so years the population will decrease significantly.  There is also a lack of very old cacti, which indicates that the population of saguaros was once much smaller than it is now.  While I suspect the saguaro population may be decreasing due to lower rainfall during the past two decades, a few years of good rain could easily allow for the establishment of many young saguaros and cause the population to bounce back.  So there is no immediate reason for us to fear the disappearance of the saguaro from the White Tank Mountains during our life time.

A saguaro cactus with a drooping arm.  Typically, arms drooping down like this means the cactus was damaged by freezing temperatures. 

And this concluded the White Tank Mountains South to Goat Camp to Bajada Trails tour.  Hopefully it was interesting or helpful, even if you don’t hike these trails yourself.  In my 150 mile hiking goal for 2012 I currently am at 15 miles.  I have a few trails I have hiked and have yet to write about and you’ll be seeing them in the near future.  Also, if you have any questions about anything pertaining to this post, or any post, let me know.  I want to make everything here on Practical Biology of course practical, interesting, and educational.  Thanks!

A crested saguaro cactus along Bajada Trail.

White Tank Mountains South Trail Nature Hike

Two Saguaro cacti in the White Tank Mountains Regional Park.

When it comes to viewing Saguaro Cacti and an unusual bajada or alluvial fan formations, the South and Bajada Trails in the White Tank Mountains  are about as easy and as they come, at least for the western portion of Phoenix, Arizona.  The trail begins at the South Trail near the entrance of the regional park, heading towards a short section of Goat Camp trail, and then to the Bajada trail, entire length about 3.5 miles and all pretty flat for some relaxed hiking.  The entire length of trail transects the bajadas, or alluvial fans, that were deposited by ancient erosion and avalanches descending from the surrounding mountainsides to the north and south of the trails and Goat Camp Canyon to the west of the trails.  Different types of deposits and differing types of drainage patterns has resulted in two major alluvial fans forming a bajada that is seemingly backwards in formation.  One of these alluvial fans though is ideal habitat for the iconic Saguaro Cacti as I will explain below.  This post will be in two parts, this first post will cover mainly South Trail.  The second post on Monday will cover mainly Bajada Trail. 

Desert dry wash along the South-Goat Camp-Bajada Trails in the White Tank Mountains.

Beginning at the South Trail trailhead near the entrance to the park, you immediately hike down into a dry wash.  This wash is one of at least a few washes that are responsible for the unusual bajada formation along the trail further along.  As most people would expect, a dry wash, also known as an ephemeral drainage, is where runoff water concentrates and flows for short periods of time following heavy rainfall.  The water only flows a short period of time because it is quickly absorbed into the loose sand in the channel where it can infiltrate very deep.  Deep in these wash sediments the water is protected from the extreme heat on the surface and is therefore a reservoir during long dry periods.  Only deep rooted plants, however, can access these reservoirs and that is why there is a concentration of ironwood and palo verde trees.  Even shallow rooted plants such as cacti and triangle-leaf bursage are in higher concentration here through, simply because there is more moisture in these washes then the surrounding soils.  Along with transporting water, washes similar to this one also transport sediments eroded from further upslope.  Washes, as they transport sediments down slope, are the major creators of alluvial fans.  Many alluvial fans were once at the end of a dry wash where the wash sort of spewed out over the surface all the sediments it transported from upslope during short periods of water flow.  Washes also are the major destroyers of alluvial fans being they erode into and carry away the sediments that compose the fans.  Because of these things, if you are familiar with the washes on a Sonoran Desert alluvial fan or bajada you can know a lot about the history of these landforms.  We will see this later on in the hike towards the end of the South Trail.

The plant community along the South Trail is mainly Cacti, Bursage, and some Palo Verde. 

Once hiking out of the wash the trail crosses onto another alluvial fan surface with a different soil type.  This soil type continues for most of South Trail.  The vegetation is characterized by shallow rooted plants, mainly cacti and triangle-leaf bursage.  This tell me that the soil is well developed, probably with a caliche horizon and maybe with a weak argillic.  Caliche is simply a rock-like calcium layer that forms about 20 inches below the soil surface in deserts and argillic horizons are deposits of clay just above the caliche.  Both layers prevent deep roots from penetrating and help shallow rooted plants become established, the most important of which is triangle-leaf bursage.  This small shrub grows everywhere along most of South and Bajada Trails and because of its abundance there is also an abundance of cacti.  Bursage functions as a nurse plant for many desert plants.  Odd as it might sound, most desert conditions are too hot, dry, and sunny for most desert plants to establish themselves without the aid of another plant.  Being bursage can establish without help of other plants, it provides the shade and slightly cooler and moister conditions required for cacti to germinate and grow under their small canopy.  The presence of bursage, along with the soil conditions, is therefore why there are so many cacti present along the South and Bajada Trails.

 To be continued Monday...

Black Rock Trail White Tank Mountains: Touring a Bajada

Lower alluvial fan, furthest away from the mountains, of the bajada on Black Rock Trail in the White Tank Mountains.  Cacti and bursage, shallow rooted plants characterize this part of the bajada indicating some caliche development in the soil.  Creosote, a deeply rooted plant shows that this caliche is not well developed and still allows for deep roots to penetrate it.

As for easily accessible trails, the Black Rock trail in the White Tank Mountains Park is a good one.  Crowded, but not as crowded as the nearby Waterfall Trail and the landscape is not nearly as trampled.  This particular trail has two loops, a short loop with a smooth and wide path, and a long loop which is narrower and slightly rocky.  The short loop is half a mile while the long loop which branches off and returns to the small loop is 1.3 miles.  While most hikers may find such a short and easily accessible hike sort of boring, I believe a little scientific knowledge of the area can give you some things to look for, making the hike quite interesting.  I personally would have considered this hike sort of boring if I wasn’t taking the time to examine landscape features.  But taking a little time to smell the roses, or rather examine the dirt, rocks, plants and so on, can make this boring hike quite interesting.  Looking closely, this loop is an excellent example of a classic Sonoran Desert bajada, specifically the upper to mid portions of a bajada.

First of all, a bajada is simply an aggregation of several alluvial fans.  And if you are wondering what an alluvial fan is, it is simply the sediments or dirt that is deposited on the ground by water.   Alluvial fans often make a fan-shaped landform when viewed from the air.  Alluvial fans are deposited adjacent to mountains when sediments wash off the mountain.  Several alluvial fans deposited in succession together form a bajada, and in the Sonoran Desert the further a fan is away from a mountain the younger it is.  The Black Rock Trail has a slight slope up towards the mountains.  Hiking along this slope you are hiking over very old alluvial fans which sediments were once part of the White Tank Mountains.

In the case of Black Rock Trail, there are three alluvial fans, each with is distinct soil type.  Starting off at the trail head, furthest away from the mountain is the youngest fan.  The plants indicate there is a weakly formed layer of caliche here.  Creosote is most common in this area of the trail being its deep roots do not tolerate well developed caliche layers, and therefore indicates weak caliche or an absence of it.  Triangle-leaf bursage also common to the area however requires some caliche development in the soil.  So put together bursage and creosote indicate a weak caliche horizon. 

Middle alluvial fan on the Black Rock Trail.  Characterized by shallow rooted plants such as cacti and triangle leaf bursage.  The presence of caliche in the soil favors these shallow rooted plants.

Hiking up the slight incline a short distance there is an increase in cacti, bursage, and palo verde, and a sharp decrease in creosote.  Palo verde, bursage, and cacti all seem to prefer stronger caliche development while creosote doesn’t tolerate it well.  This is the second alluvial fan, and plants with shallow roots that can accumulate above the caliche dominate this area.  Deeper rooted plants such as creosote are not able to penetrate the caliche and therefore don’t grow in abundance.

If it were just for the bajada, this trail might be at least a little boring.  But in the beginning to mid portions of the trail you pass some striking out-crops of granite.  What is striking about these out-crops is not simply that they are granite, but rather that the rocks are out of place in the bajada and that their coloration is pitch black in places.  These out-crops are sort of islands of rock surrounded by the dirt and sediments that form the bajada they pierce through.  As the bajada sediments were deposited off of the mountain these rocks remained in place, largely unmoved.  The alluvial fans and bajada was simply deposited around the rocks.  The rock formations are therefore very old, much older than the surrounding bajada.  The old age of the rock formation is indicated by the presence of the thick and very dark black desert varnish layers that color these rocks.

Granite outcropping along the Black Rock Tail.

Hiking beyond the short loop and onto the long loop the trail becomes a little rougher.  You will notice that the ground becomes increasingly rocky and more uneven.  This indicated the transition to the third and oldest alluvial fan closest to the mountain.  Here, there still may be some triangle-leaf bursage indicating caliche, but the further you go there is defiantly a shift towards more brittle bush.  Brittle bush prefers very rocky and often unstable soil surfaces, both common to this area.  There are still on this third fan a lot of cacti as well as palo verde and some ironwood trees.  The Ironwood trees seem to increase the closer you get to the Waterfall Trail, possibly a result of their deep roots accessing water that sinks deep into the sediments after if flows over the waterfall.

The upper alluvial fan of the bajada.  If you were able to see the ground you would notice that it is much  rockier and rougher than the lower two alluvial fans.  This type of soil favors brittle bush which is the shrub layer you see covering the ground here.  Cacti are still common here indicating some caliche in the soil.

As the long loop of the Black Rock Trail loops back and starts heading away from the mountains you begin your return down the bajada.  The whole trip requires at most 45 minutes or so if you go slow, and in that short period of time you can get a great tour of a Sonoran Desert bajada and the plant ecology.  Really, tours of this type don’t get any easier.  After this hike I am at about six miles of my 150 mile hiking goal for 2012.  So far so good.  I am hoping to do some longer hikes in the near future and hopefully take some big chunks out of my goal pretty quickly.  

Hiking Waterfall Trail at the White Tank Mountains

Waterfall Trail White Tank Mountains.

The appeal of a waterfall at the end of the trail probably makes the White Tank Mountains Waterfall Trail one of the most popular trails in the county (link to White Tank Mountains Park).  While the end goal might be reaching a waterfall, the scenery along the way can make the trip quite enjoyable.  Added to that, remnants of an ancient culture, easy accessibility, and a relatively short round trip, all make a good quality hiking experience for just about anyone. This year one of my new year resolutions is to hike 150 miles and to blog about it here.  I hopefully will be giving you a short nature guide tour on-line.  I want to visit each of the parks within the Maricopa County Parks system.  Which maybe will be just interesting and maybe will be helpful to you if you hike the Sonoran Desert.  Also, it might just inspire you to go hiking and do a little nature walk of your own.  This hike ticks off two of the 150 miles.

The hill or mountain side on the White Tank Mountains Waterfall Trail is rocky and drier than the adjacent bajada.  It therefore has more of an abundance of palo verde, brittlebrush and barrel cactus.

Beginning at the parking lot, the trail is very flat and universally accessible.  The first half mile or so hikes along a granite mountain or hillside to the left, and a relatively flat bajada, or alluvial fan, to the right.  Looking closely, there are some obvious differences between the mountain side and bajada.  The mountain side being obviously more rocky has a greater abundance of palo verde trees, barrel cacti, and brittle bush.  These plants are more highly adapted to rocky and droughty conditions of the hillside than to the deeper soils that absorb more water below.  On the bajada side there are far fewer rocks and much deeper soils.  Deeply rooted Ironwood trees and creosote brush take hold in this deeper soil.  There is also an abundance of triangle-leaf bursage, an indicator of a well developed soil, typically with caliche, a hard calcium deposit a few feet under the surface. 

The upper portion of a bajada along the White Tank Mountains Waterfall Trail.  Here the deeper bajada soils support more deeply rooted plants such as ironwood and some creosote bush.  Triangle-leaf bursage is also abundant and indicates a well developed soil, likely with caliche.  

At the end of the flat paved portion you will finally reach Petroglyph Plaza, an ancient art and story gallery of the Hohokam Indians.  These petroglyphs were carved into the black veneer that covers most of these large blocks of granite.  The black veneer is technically called “desert varnish” and is quite common on desert rocks that have been exposed to the atmosphere for long periods of time.  Bacteria form the varnish by carrying out a chemical reaction with dust that falls on the rock, forming the black covering.  The thicker and blacker the varnish, the longer the rock has been sitting in one location.  Most of the petroglyphs were made around 1000 years ago and too be honest we really don’t know what most of them mean.  Their meanings were lost with the Hohokam culture when they abandoned the Whitetanks about 700 years ago.

Petroglyphs found in the Waterfall Trail canyon.

Hiking past Petroglyph plaza the trail becomes a little rougher but still not bad.  Here, you start to walk along the wash that is fed by the waterfall during heavy rain.  The area around the trail becomes extremely rocky and rough.  All of the plants present earlier on the trail are still common but sort of mixed together.  In addition, jojoba is found in abundance, which seems to prefer cooler rockier areas with slightly more water, which is exactly the case in this canyon.  If you look in the wash there is also the presence of mesquite and cat-claw acacia, both of which take advantage of flows of water in the wash that happen maybe a few times each year.  Ironwood trees are oddly in abundance in this area, and are likely a result of their deep roots taking advantage of water from the wash infiltrating deep into the soil. 

This is typically what the "waterfall" looks like.  The pool at the base of the falls is all that is left after a month or so without rain.

Finally, after a mile of hiking the end of the trail and the head of the canyon is reached.  Unfortunately, searching for the waterfall at the end of this trail is little better than searching for a pot of gold at the end of a rainbow.  At least with this trail the narrow rock walled box shaped canyon is quite a spectacular site, but the waterfall is rarely flowing.  The falls run only after sufficient rainfall, say an inch or more, and typically run no more than few days after that.  But when the water is flowing it is quite a spectacular site with water gushing and shooting narrowly over the cliff far above.  Once the water enters the wash bed though it quickly sinks into the deep sediments but continues to flow downslope.  While plants and animals on the surface can’t really take advantage of this water lost into the sediments, deep rooted plants such as the mesquites and ironwoods easily absorb the water months after all traces of water on the surface have disappeared.  The waterfall and its wash therefore explain the abundance of these plants further down the canyon and along the bajada.  

The wash below the waterfall.