Suzanne BP Holguin

5-15-03

Geog 810

Ants and Termites as Geomorphic Agents

According to J. Davis’ 312 Geomorphology class, geomorphology is the

“scientific study of the form of the earth’s surface, its landforms.” Davis also taught his

class that W. M. Davis described landforms to be the result of structure, process and time

(312 notes). Unfortunately, as David Butler (1995) notes, ‘structure, process and time’

are frequently presented as if they were “operative in a sterile, nonliving void.” Animals

are an obvious element of the earth’s landscape, yet animals and their impact are often

overlooked in geomorphic teachings.

Why have animals’ role in geomorphology been overlooked? According to

Butler (1995), many geomorphologists were trained in the earth and physical sciences,

rather than the biological sciences. This, Butler (1995) states, then translates into an

examination of how surface processes affect environmental and ecological systems rather

than how biological elements of the landscape affect systems and act as geomorphic

agents. Therefore, it is within the inter-disciplinary education of Geography that Butler

finds geomorphologists trained in, and more attentive to, scientific literature in the

biological sciences(1995).

David Butler’s frustration with Geomorphology, and the reluctance in the field to

acknowledge the fundamental role of animals as geomorphic agents of erosion,

transportation and deposition, led him to coin the new term, and field of study,

‘zoogeomorphology’ to specifically examine the role of animals as geomorphic agents

(1992, 1995). In Butler’s influential 1995 book Zoogeomorphology: animals as

geomorphic agents he presents an overview of how different animals alter their

environments over time. By using the term ‘animal,’Butler includes both endothermic

and ectothermic vertebrates as well as invertebrates, and places his emphasis on free-

ranging natural populations of animals, acknowledging “as natural as possible in such a

human-impacted world” (1995). According to Butler (1995), zoogeomorphic effects

specifically involve the movement of rock, soil or unconsolidated sediments from one

location to another, regardless of the size or range of movement. While we can imagine

the zoogeomorphic effects of a digging grizzly bear or a dam-modifying beaver, it may

be more difficult to visualize the impact of terrestrial invertebrates.

Most species of ants and termites are exceptional examples of zoogeomorphic

agents because they are eusocial insects. One of the evolutionary significant aspects of

ant and termite colonies is their internal organization, and their ability to differentiate

members into different castes. All of the more than 10,000 ant species and 2,200 termite

species are eusocial insects, meaning they have the following traits in common: 1.

cooperation in caring for the young; 2. reproductive division of labor; and 3. overlap of at

least two generations capable of contributing to colony labor (Oster and Wilson 1978). It

is quite interesting to note that 12 of the 13 known groups of insects that independently

evolved eusociality belong to the single order Hymenoptera (ants, bees and wasps) with

the thirteenth being the Isoptera (termites) (Oster and Wilson 1978). The requirement of

an overlap of at least two generations capable of contributing to colony labor, in

combination with reproductive division of labor and cooperative caring, translates into

the potential for huge colonies with thousands of workers capable of maintaining their

nests for decades.

Eusocial insects in general, and ants and termites specifically, have a significant

impact on the micro-geomorphology of their surroundings. Ants and termites construct

extensive and often massive nest systems in response to their need for food,

environmental control and social homeostasis (Wood and Sands 1978). As a result, they

can have a significant effect on the redistribution of soil particles, on physical and

chemical properties of the soil and consequently on vegetation (Wood and Sands 1978).

To summarize, termites and ants can contribute to soil erosion and denudation in 3 major

ways: 1. by removing the plant cover; 2. by digesting or removing organic material that

would otherwise be incorporated into the soil and enhance soil stability; and 3. by

bringing to the surface fine-grained material for subsequent wash and creep action (found

verbatim by multiple authors, each citing different authors as the originator, Butler 1995,

Mitchell 1988, Goudie 1995, Lee and Wood 1971). How do termites and ants alter their

surroundings?

Figure 1. Active termite nest and fresh aggregates from the subsoil. Source: Jungerius et al. 1999

To give an overview for both ant and termite nests, I have referred to J. Petal’s

1978 article entitled “The role of ants in ecosystems” and Wood and Sands 1978 article

entitled “The role of termites in ecosystems” both found within Production ecology of

termites and ants (ed. M. V. Brian). The construction of ant nests with above ground

mounds and systems of underground chambers and galleries modifies the physical and

chemical properties of both soil used for construction and the adjacent soils. Ant nests

are composed of a central site where the queen lives with a peripheral set of galleries and

chambers occupied by the workers, together forming an initially small nest capable of

being built into a complex network. Ant nests are constructed from the most readily

available materials. Hence, in rocky environments, nests are made of mineral materials,

while in forests, they consist mainly of woody materials. Just as with termites, ants use

their salivary secretions as a cementing agent to hold the materials together. Smaller

particles are raised from the deeper soil layers to the surface, while organic material is

moved further down. Chemically, while the pH of ants nests depend on the soil type,

even in almost neutral soils there is a slight increase or decrease in pH within the ant nest.

The geomorphic significance of ants rests in their aeration of the soil and the subsequent

creation of soils that allow rapid drainage and throughflow (Butler 1995).

Similar to ants, termite nests consist of one or more breeding centers from which

radiate a network of galleries to transport food, water, soil and as well as other

homeostatic tasks. Termite nests may be arboreal, epigeal (mounds) or subterranean.

The construction of the nests results in transport of soil either from deep or shallow

horizons to the soil surface, suggesting that modification of soils alter the soil profile,

texture, organic matter and nutrients. The nests are constructed from soil in combination

with excreta and saliva for their cementing qualities. Just as with ants, termites create

their nests using the materials found in their environment. Soil characteristics are an

important control of mound formation, and accordingly, much can be said about the earth

where termites are not found. Specifically, mounds tends to be rare on sands due to

insufficient binding material; on deeply cracking vertisols which are unstable; and on

shallow soils where there is a shortage of building material (Goudie 1996).

Wood and Sands note from their research that the sub-surface termite galleries

can be “so numerous as to collapse under-foot, leaving deep imprints” in the tropics

(1978). To begin to understand the magnitude of termite nests, a Kenyan mound revealed

the presence of 6 km of passage and 72,000 storage pits in an area of just 8,000 square

meters (Goudie 1996). Goudie revealed that termite mounds found in the Ivory Coast

reached a height of 1m between 2-3 years after their first appearance above ground, and

that a 3m mound would then be 8-10 years old. Though mounds are obviously

abandoned at times, in Queensland, Australia mounds are inhabited for 20-40 years!

(Goudie 1995). This associated dense network of galleries, it was suggested, must affect

porosity and aeration, infiltration, storage and drainage of water and growth of plant

roots, but in 1978 when Wood and Sands put forward these statements, none of these

important effects had been measured, only questioned. By 1996, Goudie more

confidently explains that termites found in huge numbers in fact do have a very high

biomass, create major structures, move large quantities of soil in the process of making

their nests, consume very appreciable amounts of litter and wood debris, create new soil

horizons, cover sands and stone lines, and probably exercise major control on the rate of

operation of such important physical processes as infiltration, surface wash, rain splash

detachment and soil creep (1996).

Through the formation of their extensive nests, ants and termites alter the micro-

geomorphology of their environments. Specifically, ants and termites increase

infiltration through the excavation of the chambers and galleries that form their nests.

Whereas the excavated holes a larger animal might make, such as a rodent, is referred to

as piping, the ant and termite literature refer to tunnels, with openings called macropores.

One of the earliest studies investigating water infiltration in termite nests was the 1986

article by Elkins et al. In the Chihuahuan desert ecosystem of Southern New Mexico,

Elkins et al. distinguish a mere 6 samples of both termite and termite free plots (treated

with insecticide). Elkins et al. used rainfall simulation at an average intensity of

124mm/h-1 to compare infiltration and run off on arid areas where subterranean termites

had been eliminated four years prior to the initiation of the study, compared with adjacent

areas populated by subterranean termites. Elkins et al. (1986) suggests that termites

could be an important element in the maintenance of hydrologic stability through

subsurface tunneling and soil profile disturbance.

Elkins et al. (1986) state that the most important finding in their study is that in

the absence of subterranean termites, “soil porosity is reduced thereby reducing water

infiltration.” This is an interesting way of twisting words so as not to imply there was

significance found in the water infiltration on termite plots, since it was lacking. Yet, the

authors suggest that in the northern Chihuahuan desert, subterranean termites are

“keystones” in the structure and function of that system (Elkins et al. 1986). Elkins

concludes that termite activity on watersheds in the Southwestern United States appear to

be a beneficial ecological process allowing greater short-term soil water storage, while

effectively checking erosional losses of soil and organic matter (1986).

While Elkins et al. (1986) recognizes that termites are a significant factor in the

regulation and maintenance of hydrologic responses, their early study falls short of

making a concrete connection between termites and infiltration rates. Over time, it is

intriguing to study the changes in experimental design and research concerning termites

and infiltration. Elkins et al. 1986 study begins to hint at the connection, yet falls short of

showing significance between termites and infiltration. As each researcher studies

previous experiments, we can trace the evolution of thought and experimentation,

increasing the levels of statistical significance, while always promoting termites as

fundamental components of soil-water economy and stability.

Ten years after Elkins’ study, and with a slight increase in thought regarding

experimental design, Mando et al. (1996) found termites to be the “most important soil

fauna in the Warm Seasonally-Dry Tropics” due to their impact on soil properties and

soil genesis. The experiment consisted of 4 plots, split in half to denote a Termite and

Non-Termite area. The plots were covered with a mulch of straw and wood to attract

termites, while half the plot, the Non-Termite sides were treated with an insecticide to

prevent termites from nesting. Insecticide was applied every two weeks, and after six

months, termites successfully inhabited the Termite side, while the Non-Termite side was

termite free. Mando et al. (1996) conducted “three [rain] simulation[s] of 60 minutes

duration” on each plot with an intensity of 50 mm/h. The second simulation was

conducted 24 hours after the first, and the third simulation was conducted 72 hours after

the second simulation (1986). During the rain simulations, the time between the

beginning of the simulation and the onset of ponding was called ponding time (PT), while

the elapsed time between the onset and the end of the runoff was called runoff time (RT),

which was recorded every five minutes. Therefore, the difference between rainfall

intensity and runoff intensity provided the cumulative infiltration and the infiltration rate

(Mando et al. 1996).

The results from Mando et al. (1996) demonstrate that termite nests do increase

infiltration, but at such a low sample size few of his results are statistically significant.

After six months, 88 (SD=5) open tunnels per square meter were found on the Termite

plots. According to Mando et al. (1996), cumulative infiltration after 30 minutes of

rainfall in the termite plots was higher than in Non-Termite plots, yet infiltration

decreased with increasing number of rain simulation. Since runoff measurements were

taken every 5 minutes, infiltration rates were also measured at half an hour, even though

technically the rain simulator was used for sixty minutes. While much of the experiment

lacks statistical significance, Mando et al. do demonstrate a trend between termite nests

and increased infiltration. Perhaps after only six months, termite nests are still in their

initial phases and are not well established. Additionally, a larger sample size would have

given the study more replications and hence more data.

Conveniently, Mando’s 1997 experiment combines three years worth of

infiltration data on a total of 24 Termite and 24 Non-Termite plots in a similar design to

his earlier study. Indeed, Mando found that termite activity resulted in a statistically

significant increase of water infiltration along with water storage and drainage. Mando

(1997) is sure that the “results prove that termite activity is a key element in the efficacy

of mulching to improve the infiltration capacity of crusted soil” because termites improve

infiltration through their tunnels excavated from soil.

It was the combination of termites and mulching in Mando’s 1997 study, which

increased the water storage capacity of the soil. Mando confirms that termite activity has

an effect on the soil water balance of crusted soils by increasing the infiltration amount,

soil water storage and drainage. The implications of Mando’s 1997 study are great,

suggesting that termite activity should be investigated and accounted for when

characterizing catchment hydrology and land management applications in the Sahel,

West Africa. Mando concludes by recommending the use of termites in soil and water

management techniques because of the “positive response of natural vegetation or crops .

. . due to termite effects” (1997).

The most complete and rational examination of termites and water infiltration was

performed by Leonard and Rajot entitled “Influence of termites on runoff and infiltration:

quantification and analysis” (2001). Having the benefit of so many previous studies,

Leonard and Rajot are able to build upon the growing literature on the subject, especially

from sahelian environments. The authors acknowledge that the harvesting activity of

termites results in the formation of dense networks of underground galleries and tunnels

that are connected to the soil surface by foraging holes, easily penetrated by water.

Leonard and Rajot (2001) recognize much of the work done by authors cited here as well,

and directly state that while it seems clear that termites increase infiltration, the authors

do not know if the effect will be large or not. Granted, this is not the most poignant

question, and perhaps the power of this question is lost in the poor translation of their

work, but nonetheless, their statement is important. The conditions under which many of

the past experiments had been performed are largely unnatural according to the authors

(2001). Specifically, Leonard and Rajot question the very high rainfall intensities of the

simulations (124mm/h-1, Elkins 1986) or high termite activity in a dense area that is not

representative of the surrounding environment (as in Mando 1997). The authors do

though, cite Mando’s 1997 article as the “most reliable result so far obtained on the

influence of termites on infiltration . . . increas[ing] by a factor of 1.5 due to the presence

of termites under 3 years of natural rainfall” (2001).

Leonard and Rajot (2001) state their study was performed under natural

conditions of rainfall, runoff and infiltration over the course of four consecutive years.

Once again, the experiment takes place in a sahelian environment, attracting termites to

crusted soil using a mulch. Six plots with five treatments in each were set up for a total

of 30 ‘sites’. The five different treatments in each block consisted of a control, which

was simply erosional soil, a mulch, mulch with insecticide, mulch with herbicide and

mulch with insecticide and herbicide. It should be noted that the authors realized at a

very late date in their research that the insecticide used also acted as an herbicide,

therefore preventing the ability to measure vegetation activity in the absence of termites.

In total then, there were 12 plots considered with termites, and 12 without.

Leonard and Rajot’s study was the first in my research to account for different

species of termites and their differing effect on the environment. Two species of termites

were predominant in the study, Macrotermes subhyalinus constructing above ground

mounds, while Odontotermes sp. excavated underground nests. Both of course include

dense networks of galleries near the soil surface. Of the many experiments performed,

water infiltration relates most to the current theme, and the authors used a rain simulation

of 40-mm for 1 hour. While the authors may boast of the natural-conditions of their

experiment, not only was the rain simulator used (of which the efficacy and reliability

was brought into question by a colleague in seminar) but methylene blue was added to

the water to colour the network of active galleries. The authors do not account for any

potential negative repercussions from using the rain simulator use or how methylene blue

might negatively affect the termite nests, perhaps disrupting the colony and therefore

creating an unnatural environment. In the end, it was determined from the methylene

blue that the galleries were only partially filled with water, not submerged (2001).

As expected, there is a relationship between the intensity of termite activity and

runoff, since the greater number of termite foraging holes reduced runoff (Leonard and

Rajot 2001). Yet, there is considerable variability which the authors must rationalize,

since the results showed that infiltration could be high with no macropores, and it was

also low at times despite the presence of macropores. The authors argue that although

infiltration increased with termite activity, at least 30 macropores per square meter were

necessary for significance. Perhaps, the authors suggest, even when the macropores are

closed or no longer visible, the infiltration capacity may still be high because the soil

crust has been destroyed (2001). In addition, when macropores are present their effect

may be imperceptible if they are located away from where the water concentrates

(Leonard and Rajot 2001). Leonard and Rajot (2001) conclude that while termites have

an influence on infiltration and runoff, it is difficult for them to quantify the effect due to

the high variability. The authors consider their study to be under natural conditions with

a large range of termite activity resulting in the infiltration increase by a “mean factor of

2-3,” similar to Mando (1997).

The fact that termites increase infiltration due to their extensive excavated

galleries seems somewhat obvious, even if designing an effective experiment is difficult.

What about the influence termites may have on the structure of the soil itself? Jungerius

et al. (1999) questioned the hypothesis that termites contribute to a stable microgranular,

or finely aggregated soil structure. Microaggregates, according to the authors, are often

very stable and give the soil a loamy texture, yet the origin and formation of the

microaggregates are not known (1999). Apparently, there is no clear relationship with

type of parent material, and microgranular soils have been found extensively on granites,

gneisses and sandstones, as well as dolomitic and phonolitic lava (Jungerius et al. 1999).

The authors chose to investigate termites and their role in microaggregate formation

because of the two ways termites can produce aggregates: 1. when soil is excavated and

carried in the mandibles and dumped on the surface or used in the above ground

formation of the nest, and 2. surface soil material passes through the intestinal system

when termites are feeding, and is excreted as fecal pellets (1999). Jungerius et al. (1999)

investigated the micoraggregates in the successive stages of the termite mound

development.

Above ground mounds or epigeal termite nests are “particularly numerous” on the

bottomlands of Kenya for two reasons mentioned by Jungerius: 1. occasional flooding

compels the termites to have their nests elevated to avoid inundation (an evolutionary

adaptation) and, 2. partly because the termite mounds have not been removed by

agricultural practices (1999). Though an ultimate and a proximate explanation is given,

the origin of raised termite mounds is not as pertinent as whether the authors indeed

found evidence to support their hypothesis. By combining stereomicroscopic and micro-

morphological techniques Jungerius et al. (1999) conclude that the structural units of

microgranular soil in the tropics could be formed by termites, even if their conclusion is

slightly hesitant. Termites produce stable microaggregates of about 0.6 mm in size, while

particles over 2 mm are not carried by termites and hence, coarse fragments gradually

concentrate at the bottom of the nest (Jungerius et al. 1999). The size of the

microaggregates are therefore, determined by the mandible size and ability of termites to

carry particles to the surface.

Since termites have been shown to alter their environments by increasing

infiltration and producing microaggregates (Elkins et al. 1986, Mando et al. 1996, Mando

1997, Leonard and Rajot 2001 and Jungerius et al. 1999) one must question the role of

ants in micro-geomorphologic change as well. Beginning with some of the earlier studies

of ant mound influences, Carlson and Whitford (1991) studied soils properties associated

with nest mounds of the western seed harvester ant, Pogonomyrmex occidentalis, near

Los Alamos, New Mexico. Of the 15 active nest sites selected for the soil study, Carlson

and Whitford found that ant mounds were significantly uniformly dispersed (perhaps for

territoriality reasons) with significantly higher concentrations of NO3, P and K (1991).

The ants excavated approximately 650kg/ha over the course of 3 months from June to

August in 1987. The authors’ results suggest that ants preferentially transport particles in

the order of gravel > sand > silt > clay, perhaps because at higher elevation gravel

mounds would be advantageous since gravel heats up quickly (Carlson and Whitford

1991). The authors decide, rather than demonstrate, that ant activities enhance soil

nutrient status, and that ants alter their environment according to changing needs.

Though much of the authors’ work is anecdotal, it suggests that further studies are needed

to better understand the role of ants and micro-geomorphology.

Dean and Yeaton begin their 1993 article acknowledging that the actions of any

animal that contributes to the movement of organic matter underground, (such as termites

or ants) must influence the local distribution of moisture and plant nutrients in the soil.

Specifically, in the southern Karoo, South Africa, nest mounds of the seed harvester ant,

Messor capensis, were hypothesized to contain more moisture, have a higher organic

matter content and an elevated nutrient status compared to surrounding areas (Dean and

Yeaton 1993). While the authors did successfully prove that nest mounds have an

elevated plant nutrient status compared to inter mound areas, strangely, the soils of seed

harvester ant nest mounds were actually significantly drier than soils in inter-mound

spaces! To explain this unexpected result, Dean and Yeaton suggest that soils at the base

of the mounds absorb water more quickly during rain than inter-mound soils, and the

authors state that “It is clear that nest-mound soils also dry out faster than inter-mound

soils” (1993).

Dean and Yeaton (1993) apply their results to the theories connecting infiltration

and ants nests, and recognize a trend. Nests of seed harvester ants may improve

infiltration by creating patches of less compacted, organic rich soils, ideal for plant

growth. While ant nests remained drier than inter mound soils, the authors suggest that

the infiltration ability of the nest-mound soils take up more water after it rains, and that

perhaps the soils below the nest mounds hold water at a greater depth than measured in

the study (Dean and Yeaton 1993).

Micromorphological characterizations of ant nests appear to be absent in the

literature, according to Wang et al. 1995. Therefore, their research objective was to

characterize the effect of L. neoniger Emery on physical and chemical soil modifications

while, 1. examining the geometry of nest castings and nest development; 2. describing,

measuring and interpreting micromorphological features of the nests from thin sections;

and 3. comparing selected chemical properties of ant crater rims and nests with that of

associated bulk soils. Ant nest casting are extensive and varied from 0.15 to 0.70m in

depth, while most of the galleries and chambers were concentrated in the upper 0.3m of

the soils profile (Wang 1995).

Concerning the micromorphological characteristics of the ant nest, Wang et al.

suggests that ants scavenge specifically for silt and colloidal material in addition to the

excavation materials to stabilize the nest walls. Nest walls are about 1 mm think and

have dark infillings of fine-sized soil materials (<0.25mm) between sand grains (1995).

Wang et al. (1995) found greater concentrations of silt and colloidal-sized materials,

rather than bulk soil, within the nest walls, while the outer edge of the wall appeared as

though it was intentionally arranged by the ants to have the flat surface facing the inside

of the nests. Wang et al. suspect that the ants are attempting to create a smooth path

within their nest! It appears that while excavating and constructing their nests, the ants

have rearranged and compacted the soil particles to a preferred orientation while using

specifically fine-particles as nest stabilizers (Wang et al. 1995).

Wang et al. concludes that the primary effect of the ants was mixing the upper

0.7m of soil (1995). Estimated soil turnover time ranges, for the upper 0.3 m soil from

approximately 1,000 – 2,800 years, and for soils between 0.3 and 0.7 m depths, estimated

soils turnover time ranges from approximately 9,000 – 24,000 years. Wang et al.

demonstrate the impact ant colonies can have on our environment and the rate at which

ants can alter the top soil.

For an investigation of the effects of seed harvester ants on the fertility, rainfall

infiltration, structural properties and water repellency of top soils in semi-arid rangeland

in SE Spain, we turn to Cammeraat et al. 2002. Of the 20 ant colonies located in the field

in June of 1997, nest mounds were found to have significantly lower pH than bulk soil

(Table 1). Electrical conductivity and concentrations of NO3-, NH4+, P, K, Mg and

organic C were significantly greater in soils from ant nest mounds (Cammeraat et al.

2002). Table 2 compares particle size distribution of soil samples taken from ant nests

and control sites, showing that all samples were “gravelly loamy sand” with differences

between the samples being small (Cammeraat et al. 2002). Infiltration rates were found

to be significantly higher on the ants’ nests when compared to the control area, where as

the same study performed a year later in 1998 resulted in infiltration rates being lower on

the nests. Cammeraat et al. conclude that ants’ nests act as sinks for water under slightly

humid to wet conditions, whereas under extremely dry conditions the infiltration is

reduced (2002).

Most of the research on ants and termites as agent of geomorphology has taken

place outside the United States. To bring the questions home, S. B. Vinson writes of the

invasion of the red imported fire ant to the southeastern United States (1997). Within six

months of colonization, a mound can reach about 7-15 cm across and 3-6 cm high,

containing several thousand ants (Vinson 1997). A mature fire ant colony may have

200,000-300,000 workers constructing a mound that may reach 30-50 cm in diameter and

over 35 cm high (Figure 2, Vinson 1997). The number of mounds per hectare range from

50-75, certainly suggesting geomorphic agents at work! Figure 3 is a great example of a

landscape altered by the presence of fire ants (Vinson 1997).

Figure 2 and 3 of fire ant nests, often 35 cm high, with over 500 mounds per hectare. Source: Vinson 1997

Fire ants are known for building large mounds at high densities throughout the

southeastern United States. According to Green et al. (1999) fire ants represent a new

soil-forming factor for the in the region, and hence, performed a study to quantify the

channel network geometry, clod density, aggregate stability and micromorphology of the

mounds on three texturally different soils to examine the moisture relationships in the

mounds (Green et al. 1999). Of significance to this paper, it was determined that the

fragile crust of the ant nests allowed more infiltration than the surrounding soils, with a

moisture content of up to 170% greater in the mound than in the adjacent soil shortly

after rainfall (Green et al. 1999). The authors determined that infiltrating water rapidly

drained from the mound and had the potential to be stored in the channels below the

mound. Interestingly, after one week of rainless conditions, moisture levels in the mound

and the upper part of the underlying soil were extremely low, much lower in fact than the

surrounding undisturbed soil (Green et al. 1999). The authors conclude that the mound

allows for more infiltration than undisturbed topsoil and more leaching within the mound.

Infiltrating water, according to Green et al. (1999), drains rapidly and can be stored in the

channels below the mound, as indicated by the occurrence of free water below mounds at

120, 81 and 46cm deep, while no free water was present in adjacent areas.

Green et al. (1999) recommend that as colonies relocate their mounds over time,

entire landscapes may be exposed to the greater leaching and soils may inherit new

macropores and soil aggregates. Imported fire ants affect their surrounding and hence

geomorphology by the creation of new macroporosity through their channel network as

well as aggregates and hence, alter the hydrology of the soil (Green et al. 1999). Green et

al. (1999) recommend that the presence of many mounds on the landscape may

noticeably alter the ecology and hydrology of the entire landscape, and therefore, the

imported fire ants represent a new soil-forming factor influencing the structure and

hydrology of the soils of the southeastern United States.

This research paper has demonstrated how effective ants and termites are as

geomorphic agents. It appears quite clear that ants and termites are certainly altering the

environment, even while on a micro-geomorphic scale. I found much more research than

expected, though much of the it fell short of statistical significance, repeatability and

application to the larger field. A more detailed analysis of a smaller set of experiments

would be an effective strategy to isolate one aspect of geomorphology, choosing from

infiltration, soil formation, microaggregates and nutrient changes. It is the goal of this

paper to introduce the subject of ants and termites as zoogeomorphic agents and to act as

a reference on the subject. The field of zoogeomorphology has been growing, and the

role of invertebrates as geomorphic agents has been increasingly recognized. As humans,

we often forget the significant role non-human animals have on the world, and as we

have learned, even the smallest invertebrates are capable of changing landscapes over

time.

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