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1. Module 10 The Effects of Topography and Parent Materials on Soil at Mount Lemmon and Biosphere 2 Center Cover Page Yuko Chitani Mei Ying Lai Lily Liew Asma Madad Adam Nix Eli Pristoop J.C. Sylvan SEE-U 2001 Biosphere 2 Center, AZ Professor Tim Kittel, TA Erika Geiger

2. Introduction: Soils Soil is one of the most important bases of terrestrial ecology because it provides a variety of requirements for plants and animal life. The principal properties that soil provides for plants are anchorage, moisture storage (in that soil is like a sponge storing water), and a supply of nutrients. Soil creates habitats for animals by providing space for them to live and by determining the local chemistry. One of the many definitions of soil is: “The unconsolidated mineral matter on the surface of the earth that has been subjected to and influenced by genetic and environmental factors such as parent material, climate (including moisture and temperature effects), macro-and microorganisms, and topography, all acting over time and producing a product—soil—that differs from the material from which it was derived by many physical, chemical, biological, and morphological properties and characteristics.” (as quoted in J. P. Kimmins, 1997, Forest Ecology: a Foundation for Sustainable Management, 2nd edition, Prentice Hall Press.) Many animals play important roles in the soil, including insects (springtails, beetles, and ants), mites, millipedes, nematodes, annelids, mollusks, burrowing vertebrates, mycorrhizae, bacteria, and plant roots. Desert soils are not turned over very often, but ants and burrowing mammals do most of the turnover that occurs. Plant roots also do much of the initial breaking of the parent material into smaller components. Soil has been called the least renewable resource in the ecosystem. Unlike biodiversity, plant growth, water resources, and most other components, soil takes decades to be replenished if it is lost. Steve Slaff talks with students about the soil profile at the summit of Mt. Lemmon. The three most important mechanical properties of soil are texture, structure, and porosity. Texture is the composition of the soil, or simply, what the soil is made up of. Some soils are made up of sand, silt, and clay. Determining the texture of a soil is a process that will be further explained in the methods. The structuredeals with the shape, size and grade of particles. Soil structure refers to how the individual sand, silt, and clay particles are arranged into stable aggregates Porosity or pore space of soils is calculated from the Bulk Density (Db) and Real or Particle density (Dp). Texture, structure and organic matter are all important in determining the overall soil porosity. Coarse textured sandy soils have larger pores but much less pore space than finer textured clay soils.Soil is the link between the organic and inorganic world.

3. There are five factors that determine how a soil develops. • Parent material • Particle size- dune sand vs. clay alluvium • Chemistry, soluble limestone vs. decomposing granite vs. resistant basalt • Regional Climate • Temperature- cold favors humus accumulation {organic material is added faster than it decays}: heat allows humus to decompose rapidly. • Water flux- mineral leaching by high rainfall vs. Caliche formation under low rainfall. • Organisms • Organic matter input- acidic pine needles vs. grass roots. • Vegetation cover – determines rate of organic input and rate of surface erosion. • Bioturbation due to prairie dogs, earthworms, termites, etc. • Topography • Water flow • Whether a soil will be eroded, stable, or covered by more deposits. • Solar radiation loading, which affects soil temperature and evaporation rate. • Time • Soil genesis – It takes time for soil to develop • Surface stability • Climate changes-the longer the time, the more likely that climate will change. • Human disturbance—grazing, land use, and fire. Steve Slaff describes the parent materials in the Santa Catalina Range. Both physical and chemical weathering are needed for soils to form. Weathering is the process of physical and chemical changes in rocks, which are caused by atmospheric agents such as water, oxygen, and carbon dioxide. Weathering takes place at the earth’s surface. Weathering may involve the disintegration of rocks into smaller particles, or the decomposition of rocks into different minerals. Long-term weathering often forms various kinds of clays. In this lab we examined soils from two different sites, analyzed, and compared them. What differences or similarities do soils from different topographical areas have? What differences could topographical factors have that influence the kind of soil and soil production?

4. L, F, H & O LAYERS Horizon Definitions The second component of soil structure is referred to in terms of soil horizons. The materials arriving at the surface layer, such as leaf litter and other dead organic matter, are processed within each horizon and then pass through to the layer beneath it. The horizons are abbreviated to single letters, and unfortunately the nomenclatural systems differ between continents. The top layer is the litter layer (L), composed of litter that is slowly decomposing and has been only recently deposited, but is rapidly being broken down by biotic activity. The next layer is the F layer, a rapidly decomposing layer of litter leading to an accumulation of a layer of “raw” humus (horizons H and O - horizon O has material that is more decomposed than horizon H) below it. The H layer has litter that has been broken down to particles and is usually very nutrient rich. Below the humus layer, are the alluviated layers (A horizons), layers that are very poor in metallic elements like iron and aluminum, elements which have been leached out (alluviated) of the forest floor to the B horizons below. The alluviated B horizons are layers that are rich in deposited iron, aluminum, and other minerals (alluviated) that were leached out of the A horizons. Below the B horizons lies material that are not considered soil—the C horizon consisting of unweathered parent material or compacted rock materials. The C horizon begins the bedrock layers, where biological activity is almost non-existent. A LAYER B LAYER C LAYER  The soil profile at the Mt. Lemmon site; notice the four distinct layers (or horizons) in the bank.

5. Map of Two Sites Mt. Lemmon Biosphere 2 Center

6. Map of Regional Soil Profiles MH2- Haplustolls- shallow, moderately slowly to slowly permeable soils that formed in eolian material over residuum derived from basalt. TS6-Torrertic Haplustolls (New classification: Torrertic Hoplustolls) clayey texture and deep wide cracks that are open more than 6 months in most years formed in clayey sediments, soft shales, or basic rocks, in association with Aridisols and with aridic subgroups of Ustolls. TS7-The Caralampi series consists of very deep, well drained soils formed in fan and slope alluvium from granitic and volcanic rock. -very gravelly sandy loam - rangeland. TS10-The Cellar series consists of shallow and very shallow, somewhat excessively drained soils formed in slope alluvium from granitic rock.- very gravelly sandy loam – rangeland. FH5-Mirabal Baldy- Mt. Lemmon site. Loamy sand. Bolsa quartzite.

7. Climate Diagram of Mt. Lemmon Area Courtesy of the Desert Research Institute website: http://www.wrcc.dri.edu

8. Methods Using screen sieves, we separated each horizon of the soil profile into 5 different particle sizes (#5 mesh-gravel, #10 mesh-fine gravel, #60 mesh-course sand, #230 mesh-fine sand, bottom pan-silt and clay). Using a balance scale, we weighed each of the particle types from each of the horizons (Tables 1&2). We then used Excel to determine the percent composition for each horizon at each site. Another part of testing the soils texture was with a flow chart that helped determine the texture of the soil by feel. We then tested each horizon from each site on the plasticity and stickiness of the soil. Using the Munsell soil color charts for both the dry and wet soils, we identified soil colors according to a standard that is universally acknowledged. We then smudged these colors on a white piece of paper for better contrast (Results). In this lab we wanted two different soil types, so we collected a soil survey from Mt. Lemmon, from an elevation of 8,500 feet. To collect proper sample we labeled each horizon of soil, clearly distinguishing one horizon from another. After labeling the horizons we measured the depth of each horizon. In order to get the purest sample of each horizon we dug a vertical profile. This vertical profile allowed us to dig at the side of the soil, which helped prevent other horizons from contaminating the sample. We then carefully bagged the soil from each horizon and labeled them. This method of sampling was also used on the soil profile at the Biosphere 2 Center campus. The second soil profile was collected at 3,852 feet. After we took these samples, we analyzed them at the dry lab. We performed a series of tests, such as the sieve screen test, plasticity tests, texture makeup tests, the smudge test, and the Munsell soil color test. The sieve screen test has five pans, and 4 of the pans have screens filtering particles from largest to smallest, and the last pan collects what remains. The mesh sizes are 5, 10, 60, and 230. A mesh size is an indication of the number of openings per linear inch. This test allowed us to separate soils to examine their texture on four different levels. Excavating a soil profile at the Biosphere2 site.

9. Geologic Formations: Mt. Lemmon and Biosphere 2 Center Mount Lemmon: Naco group – metamorphosed Paleozoic sequence, mostly limestone, Bolsa quartzite Biosphere 2 Center: Dissected Neogene basin fill, overline terrace and pediment gravel sheets and local alluvium

10. O O A A B B C C R Top: Mt. Lemmon soil profile analysis, Mei and Adam working on the texture tests. Bottom: Biosphere 2 soil profile analysis, Asma working on the Munsell color and smudge Tests. Top: Mt. Lemmon profile (Letter denotes layer) Bottom: Biosphere 2 soil profile Top: Detail-view of Mt. Lemmon soil profile Bottom: Detail-view of Biosphere 2 soil profile A B1 A B2 B1 B2

11. Pyramid of Soil Texture Biosphere2 Mt. Lemmon

12. Table 1 – Mount Lemmon Lat/Long: 32.44˚ N / 110.78˚W, Elevation: 2764 meters, 8500 feet Site Description: Old growth, near summit, cooler, breezier climate, more rainfall, more organic materials

13. Soil Composition – Mount Lemmon

14. Table 2 – Biosphere 2 Center Lat/Long: 32.57˚ N / 110.84˚W , Elevation: 1174 meters Site Description: Arid, Desert, grasses, small trees, succulents shrubs, less than 10" of rain, alluvial deposition

15. Soil Composition – Biosphere 2 Center

16. Results • Based on the Texture Analysis and the Munsell Color Test, the soil profiles of Mt. Lemmon and Biosphere 2 are as follows: • Mount Lemmon • O: +3cm – black/brown, charcoal, leaf litter • A: 0~-26cm – dark grayish brown, sandy loam • B: –26~-46cm – yellowish brown, sandy clay loam • C: -46~-156cm – brown weathered rock, loam • Bedrock: -156~ • Biosphere 2 • A: 0~-30cm – brown, sandy clay loam • B1: 030~-50cm – reddish brown, clay • B2: -50~-85cm – yellowish red, sandy clay loam • B3: -85~ - yellowish red, sandy clay loam • The Screen Sieve Analysis was affected by imprecise methods (see conclusion) • Mount Lemmon • Gravel accounted for the largest percentage of mass from O to C layers. • Coarse sand accounted for most of the non-gravel mass. • With increasing depth, percentage of silt and clay decreased. • Biosphere 2 • Percent of coarse sand increased with depth in soil profile. • Less gravel than soil from Mt. Lemmon. • Percentage of silt and clay very variable among different horizons. Smudge Tests

17. Discussion: Parent Material, Topography & Soil “The unconsolidated mineral matter on the surface of the earth that has been subjected to and influenced by genetic and environmental factors such as parent material, climate (including moisture and temperature effects), macro-and microorganisms, and topography, all acting over time and producing a product—soil—that differs from the material from which it was derived by many physical, chemical, biological, and morphological properties and characteristics.” To investigate this working definition for soil, we were asked to consider two questions: What differences or similarities do soils from different topographical areas have? And what differences could topographical factors have that influence the kind of soil and soil production? To answer these we took soil from two distinct topographical locales—one from a road cut near the top of Mt. Lemmon (elevation 8,500 ft.), the other from a road cut on the Biosphere 2 campus (elevation 3,852 ft.). We looked at soil texture, color, consistency, structure; we also looked at the topography, climate, and the general characteristics of each site. Of the five functional factors that make soil (topography, parent material, time, organic forces, and climate) we found topography and parent material to have the most pronounced affect on the texture, structure, and the physical and chemical characteristics of our samples. Not that climate, biotic activity, and time are unimportant to soil development, but parent material and topography have shape how these other (crucial) factors function. The parent material at a given site influences the interaction between organic and inorganic materials—e.g. quatz and limestone weather differently and so form very different soils. Topography is a deciding factor in the microclimate. Elevation effects temperature and moisture levels at a given site; these in turn are limiting factors for the vegetation growing there and the kind of organic material that they into the soil. Eli takes a closer look at the clay. One note about time. Though it is a passive agent in this process, it is perhaps the key ingredient in the creation of soils. The process of physical and chemical changes in rocks caused by atmospheric agents such as water, oxygen, and carbon dioxide takes place over millions of years. Soil is a living process (a living labyrinth, Tony Burgess calls it) and like most living things it takes time to develop.

18. Mount Lemmon TOPOGRAPHY: At 8,500 feet, the Mount Lemmon site is a breezy mountaintop characterized by its cool temperatures and old growth forest. Ponderosa and Limber Pines, Douglas and White Firs all tower 60 ft or more over the forest floor. In the space between these trees, small stands of Quaking Aspens and Rocky Mountain Maple saplings grow. Part of the reason for high biotic productivity in the area has to do with an abundance of rainfall: 788mm of precipitation per year on average, according to the nearby Palisades Ranger Station which has been compiling yearly climate data for years (see above table). These forests benefit from late summer monsoons, as well as snowfall in late fall/early winter. Referring to the local climate of the Santa Catalina Mountains, the Arizona AgNIC reports, “On high peaks at 9000 to 10,000 feet, snow persists all winter and accumulates to 20-40 inches. Summer rains fall June - September, originate in the Gulf of Mexico, and are convective thunderstorms. Winter moisture is frontal, originates in the Pacific and Gulf of California, and falls as rain or snow in widespread storms of low intensity and long duration. May and June are the driest months of the year. Humidity is generally low. Temperatures are mild in the summer to cold in the winter. Freezing temperatures are common from October through April. Frost free period ranges from 120 to 260 days.” We were surprised at first to discover less biodiversity of plant and arthropod life at this site, but given the colder temperature regime--the minumum daily temperature in the Santa Catalinas drop below freezing during four months our of the year—a chill that many plants thriving in the lower elevations around Biosphere2 could not tolerate. Thus because of its topography, the microclimate on Mount Lemmon is much like that found in temperate forests at higher latitudes. Vegetation contributes a substantial amount of organic material to the soil profile every year as reflected in the L, H, and O layers of the soil profile. We estimated this to be 3cm in our profile. It is worth noting that we could expect more given the sheer amount of organic activity at Mount Lemmon. The fact that there was not a thicker O layer is strong evidence of the effect of erosion on overall soil formation at higher topographical points. The deep roots of the trees, and the life forms that they support, also help to break down the soil structure through the process of biturbation. These dense networks of roots and the burrows of vertebrates and arthropods that live on the forest floor provide conduits for water; thus aiding in the process of weathering of the rock material. Another contributor to the character of this O layer has been fire. Charcoal found in the litter over the O layer suggests a history of forest fires in the area. These fires allow for a much more rapid decay of organic material and nutrients than normal decomposition. Judging from the vegetation, there has not been a fire in recent years. Human disturbance even when it has profound impact of a local ecology does not tend to have any long term geological effects; for this reason it is considered more of a historical phenomenon than a geological one. In an indirect way, topography also influences human disturbance and land use policy. Mount Lemmon is a popular tourist site and is used primarily for recreation purposes. Land use in the immediate area is limited to these activities, though there is a great deal of construction on roads in the area. Currently these are the only significant disturbances to the soil.

19. Temperate forest near the top of Mount Lemmon. PARENT MATERIAL: According to Steve Slaff, the rock material that forms the basis of our Mt. Lemmon site is called Bolsa Quartzite. (He also referred to it as “Cat Mountain Rhyolite.”) The rock formations in this area were probably laid in the Pleistocene period and influence the soil type here, known as Mirbal Baldy. There is almost no volcanic material in the Santa Catalina Range of which Mt. Lemmon is a part. The parent material is broken down over time in the C layer of the soil. This fact plus the enormous amount of organic material available to the process are perhaps the two most distinguishing factors from the Biosphere 2 site.

20. Topography: Compared with Mt. Lemmon, the landscape of our second site is limited mostly by availability of water. This biome would be best classified as Apacherian mixed scrub savanna, which, according to Dr. Tony Burgess, is classified as “coexisting growth forms that include grasses, subshrubs, stem succulents and shrubs” (Burgess 1994). Long dry spells punctuated by erratic and variable rainstorms make for a very unstable plant community. This area has a much larger percent composition of grasses than the site on Mt. Lemmon. This makes the whole community susceptible to frequent fire and thus limits extensive long-term productivity. The pattern of dry periods followed by heavy rains means that summer storms cause erosion. Plants have had to adapt their root structure to these extreme conditions—grasses have quick growing shallow roots to take advantage of the heavy summer rains, trees and some shrubs tend to send deeper roots into the soil to take of water that seeps deeper into the profile during winter storms. Warm average temperatures protect species vulnerable to frost—trees like the mesquite, and succulents. Sandy soils work to the advantage of these type of trees, since they are more porous and allow for more water during the characteristic heavy storms to penetrate deeper into the soil profile. • Another factor in the topography of this site is extensive grazing. While the ground directly above our sampling site did not appear to have been grazed recently, the Apacherian savanna has historically been overgrazed. Overgrazing can erode the soil, by trampling microorganisms that help knit the soil structure together. They also significantly reduced the amount of biotic material available to the soil process. When cattle are introduced to the ecosystem, much less biotic material and nutrients are returned to the soil. Compared to the Mt. Lemmon site, there is very little litter at the Biosphere 2 Center. The topography is marked islands of fertility under trees where litter and hungry nutrient grasses tend to gather leave top soil levels vulnerable to erosion. This may have had something to do with why we found no O layer at the Biosphere 2 site. Biosphere 2

21. Parent material: The geological basis of Biosphere 2 is called the Cordones Surface. It is part of an ancient alluvial fan deposited by runoff from the Catalina Mts. during basin and range faulting. The Cordones Surface formed from mixed alluvial deposits of different kinds of rocks including Paleozoic sedimentary rocks, metamorphic rocks, and Tertiary granites Since then, two processes have prevailed over time in the creation of this soil composition. Eluviation occurs when water percolating down through the soil leaches substances out of the upper layers. The acidic water dissolves most minerals, except quartz, and carries them deeper into the soil. Illuviation occurs as water percolating down through the soil carries materials from upper layers into deeper layers. An illuvial soil horizon has accumulated clays or minerals transferred by water flow from overlying soil. Over time these two processes can change a uniformly mixed alluvial deposit into a mature soil with distinctly different horizons (Burgess). This explains why we found clay interspersed many rounded rocks in the soil horizon. Clay comes some from weathering within the original deposit but most is brought in as windblown dust and raindrop nuclei. This dust often consists of oxidize iron-based material which give the soil a ruddy appearance. You can see this in the smudge tests: the samples from B2 are much redder than those on Mount Lemmon. Percolating water gradually moves clay particles down through the soil. In early stages this forms clay films on clods and pebbles. As clay continues to accumulate, water movement within the horizon is slowed; hence clay is not moved into deeper layers, forming with is called an argillic horizon. On ancient alluvial fans, such as the Biosphere 2 campus, Holocene erosion has exposed the Pleistocene argillic and calcic horizons. These exposed layers become parent material for new soil formation. This process is typical of lower elevations in the Basin and Range Geologic Province. Over time the low level of precipitation (usually less than 12 inches per year) forms a horizon of caliche, a cement layer made from calcium carbonate (Burgess). This layer is almost nonexistent in areas of greater and more consistent precipitation (like the temperate forests of the Northeast), but we found that it was very prevalent on the B2C campus. The presence of caliche was one of the major differences between the soil profiles. McAuliffe in his essay on desert soils in the Natural History of the Sonoran Desert describes the slow process by which caliche horizons are formed: “They start as thin, patchy coats of whitish calcium carbonate on the lower surfaces of pebbles and small stones….These weakly-developed calcic horizons can form within a few thousand years. Accumulation of more calcium carbonate eventually produces thicker, continuous coatings on pebbles and stones or pronounced whitish nodules in fine-grained parent materials. Eventually, additional accumulation of calcium carbonate fills the soil interstices between pebbles or nodules and the calcic horizon becomes plugged, greatly restricting the downward movement of water. Once this occurs, calcium carbonate may continue to accumulate on the top of the calcic horizon in hard, cemented layers and may literally engulf and obscure overlying soil horizons in the process. It takes many tens to hundreds of thousands of years for such strongly-developed calcic horizons to form. Sometimes hard, whitish caliche becomes exposed on the surfaces of very old soils when erosion removes overlying, less erosion-resistant soil horizons. These partly eroded soils are very common throughout the Sonoran Desert and are called truncated soils.” Thus the presence of a caliche layer not only tells us something about the content of the soil, it also serves as evidence of the climate that created it. The thick caliche layer we found in out Biosphere 2 sample would suggest that this area has experienced extreme aridity for quite some time. It can also give us a picture of the future topography and soil composition since caliche “erodes unevenly to create exposed or slightly buried surfaces that shed water in weathering crevices, resulting in a landscape with patchy water infiltration and retention,” and facilitating even more run-off, and more erosion, during heavy summer thunderstorms (Burgess). The geology of the landscape also exacerbates many of the environmental/climatic factors that shape this community and the soil profile, and creates a patchwork of different soil textures and characteristics. This is partly why desert soils are so hard to classify.

22. The Formation of Caliche in Arid Soils From Phillips and Comus. 2000. Natural History of the Sonoran Desert. Arizona Desert Museum Press. Tucson.

23. Conclusion • How did the soils differ? How does topography affect local climate? How did different parent materials result in different soils? • In this exercise, we learned various techniques for sampling and examining soil profile. For example: • Sieve test • Texture tests: smudge test, ribbon (plasticity) test, stickiness test • Munsell Color Test • Topography affects climate, and together, these two factors significantly influence the soil composition. The higher elevation of Mount Lemmon results in more rainfall, and a more breezy climate. The lower elevation of Biosphere 2 results in a dryer, hotter climate. Analysis of the soils indicated that the Mount Lemmon soil had more gravel and organic material in it than the Biosphere 2 soil, whereas the Biosphere 2 soil had more coarse sand in it. This is because the Mount Lemmon site has a colder climate, where litter decomposes more slowly than in the arid climate at the Biosphere 2. The arid climate here results in less rainfall which, in turn, favors the formation of caliche found in the Biosphere 2 soil. • Differences in the parent materials of the soils also influence soil composition. Bolsa quartzite was the parent material of the Mount Lemmon soil; this material resulted in the softer, easily broken apart, weathered rock found in one of the soil layers. The parent material of the Biosphere 2 soil is alluvial deposits. Rust in the alluvial deposits results in the rust color of the soil at the Biosphere 2. • In analyzing the soil samples collected, we learned that there are not many quantitative tests that can help us accurately describe the soil composition percentages. Most of the results that we obtained were from qualitative assessments, such as the Color Test and the Smudge Test. We found discrepancies that might have a lot to do with how we implemented these tests. • In the future, we need to collect sufficient amount of soil so that we can replicate our test for more accurate results. Soil profile Biosphere 2 

24. http://www.columbia.edu/itc/cerc/seeu/bio2/index.html http://homepages.which.net/%7Efred.moor/soil/formed/f0107.htm http://www.statlab.iastate.edu/soils/osd/dat/C/CABEZON.html http://ialcworld.org/soils/nonaridisols/nonaridisols.html http://www.statlab.iastate.edu/soils/osd/dat/C/CARALAMPI.html http://www.statlab.iastate.edu/soils/osd/dat/C/CELLAR.html http://interactive.usask.ca/skinteractive/modules/agriculture/soils/soilphys/soilphys_depo.html http://www.wrcc.dri.edu McAuliffe, Joseph R. “Desert Soils”. A Natural History of the Sonoran Desert. Eds Steven J. Phillips. Arizona-Sonora Desert Museum Press: Tucson, 2000 Burgess, T. 1995 Desert Grassland, Mixed Shrub Savanna, Shrub Steppe, or Semidesert Scrub? Pp.31-67 in The Dilemma of Coexisting Growth Forms. University of Arizona Press, Tucson. Dickinson, William R. 1992. Geologic Map OF Catalina Core Complex And San Pedro Trough Arizona Geological Survey contributed Map CM-92-C. 1:125,000 Geological Society of America Special Paper 264. Macbeth, Gretag. MUNSELL SOIL COLOR CHARTS year 2000 Revised washable Edition. MUNSELL COLOR 617 Little Britain Road, New Windsor, NY 12553. Steve Slaff Lecture on geology and soil. 6/19/01, Mt. Lemmon, AZ. References & Acknowledgements