Soil Chemical Properties Dynamics in Glacial Moraines Across a Chronosequence

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Soil chemical properties dynamics in glacial moraines across a chronosequence:

Breiðamerkurjökull outwash plane, Iceland

M.S. Thesis

Presented in Partial Fulfillment of the Requirements for the Degree Master of Science in

the Graduate School of The Ohio State University

Chloe M. Turner

Graduate Program in Environment and Natural Resources

The Ohio State University

2018

Thesis Committee

Dr. Rattan Lal, Advisor

Dr. Guðrún Gísladóttir, Co-Advisor

Dr. Brian Slater

Dr. M. Scott Demyan

Copyrighted by

Chloe Michele Turner

2018

Abstract

Changes in the global climate have led to increased pressure on the natural systems; glacial retreat and melting of ice sheets are among important indicators for climate change around the globe. As the glacial retreat continues, an exposure of the terrain increases and material collected from glacial movement is deposited in the foreland. These newly exposed surfaces and materials are exposed to a variety of processes, where the soil as a whole is a function of the soil forming factors: climate, available biota, topography, parent material, time, and human activity (Jenny, 1941).

There is an overall lack of research on the soil systems chemical and nutrient properties in newly formed soils, especially volcanic ash soils. This study proposes to evaluate young Andosols (Andisols) from the exposed moraines as a result of glacial retreat. More specifically, this project will be evaluating the forms of plant-available nitrogen (N) and phosphorus (P), P-retention, C: N ratio, and a series of micro- and macronutrients.

Measurements at Breiðamerkurjökull outwash plane (Vilmundardóttir et. al., 2015), showed that vegetation succession and soil development are slow on the exposed moraines in comparison to those in nearby soils. However, a deficiency of plant available nutrients has not been evaluated and could potentially be a contributing factor. The study site also exhibits point-centered influence of seabirds on the soil, which has developed the soil and vegetation at a considerably faster rate than that on the glacial till alone. The research proposes to analyze the plant nutrients under the bird hummocks in comparison to the moraines across the 127-year old chronosequence. The data thus obtained are hypothesized to measure higher values of nutrients in these soils under the bird iii hummocks when compared to those under the moraines. Overall, the variables analyzed are focused on soil development where time is the dominant soil forming factor, but with consideration of point-centered effects of biota (seabirds).

Dedication

I would like to dedicate this thesis work to my family who have always believed in my capacity to succeed, and who have the greatest love and respect for education. Especially my sister Cat, who never let me abandon my efforts, and shares my passion for the Earth.

Acknowledgments

I would like to thank my dear friends and colleagues Kaitlyn Benson, Nall

Moonilall, Susanne Claudia Möckel, Theresa Bonatotzky, Scott Riddell, Sigrún Dögg

Eddudóttir, Dr. Egill Erlendsson, and Cody Meservy for all their support and advice throughout my program. I would not have been as successful without these wonderful people and their tremendous contributions to my understanding of soil science and the

Icelandic environment. Their passion for the research and inter-disciplinary backgrounds has been crucial to my work and personal motivation.

A great thank you to Dr. Rattan Lal who has assisted me through my Master’s program and conducting this research, by providing the means for such an interesting study, by offering counsel, funding, and hospitality. Additionally, I would like to thank the School of the Environment and Natural Resources for their financial support with my transportation to the University of Iceland. I would also like to thank the members of my committee including, Dr. Brian Slater and Dr. Scott Demyan for their significant feedback and diverse perspectives on this topic.

Special thank you to the Icelandic Research Fund, via Dr. Guðrún Gísladóttir, who supported the costs of field work in Iceland and in lab analysis for this research. This research could not have been completed without the dedication of Dr. Gísladóttir, and her efforts making my stay in Iceland so welcoming and insightful. A special thanks to

Dr. Olga Kolbrún Vilmundardóttir, in her assistance with my work in Iceland, as well as her friendship and kindness while I stayed in Reykjavík.

Additonally, I’d like to thank Dr. Utra Mankasingh and Rimal Basant with their assistance with my lab work and analysis of results. I’ve been very fortunate to have so many people that have assisted me in so many ways and inspired my passion to research the Icelandic landscape.

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Vita

2009 – 2013 ………………………………………Simon Kenton High School Graduate, Independence, Kentucky 2013 – 2016 ………………………………B.S. Geography and Environmental Science, Western Kentucky University 2013 – 2016 ………………………………Certificate Geographic Information Systems, Western Kentucky University 2014 – 2016 ………………………………….Student Technician, USDA-ARS, Bowling Green, KY 2016 – 2018 ………………………………….. Teaching Assistant, The Ohio State University

Honors 2015 – 2016 ...... …………………………… Outstanding Geography Student, Western Kentucky University

Field of Study

Major Field: Environment and Natural Resources

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Table of Contents

Abstract ...... iii Dedication ...... v Acknowledgments...... vi Vita...... viii List of Tables ...... xi List of Figures ...... xii Chapter 1. INTRODUCTION ...... 1 1.1 Climate Change in Iceland ...... 1 1.2 Iceland’s Environment and Volcanism ...... 4 1.3 History of land use management of soils in Iceland ...... 9 1.4 Classification of Soils in Iceland ...... 11 1.5 Soil Forming Factors in Glacial Moraines...... 12 1.6 Study Rationale ...... 16 1.7 Study Area ...... 20 1.8 Hypotheses ...... 28 1.9 Current Study ...... 30 1.10 References ...... 32 Chapter 2. SOIL CHEMICAL PROPERTIES DYNAMICS IN GLACIAL MORAINES ACROSS A CHRONOSEQUENCE: BREIÐAMERKURJÖKULL, ICELAND ...... 39 2.1 Abstract ...... 39 2.2 Introduction ...... 40 2.3 Materials and Methods ...... 41 2.3.1 Study Site ...... 41 2.3.2 Experimental Design ...... 45 2.3.3 Field Measurements and Soil Sampling ...... 48 2.3.4 Sample Analyses ...... 50 2.3.4.1 Sample Preparation ...... 50 2.3.4.2 Phosphate-Retention (P-Retention) ...... 50

2.3.4.3 Soil pH (H2O) ...... 51 2.3.4.4 Soil pH (NaF) ...... 51 2.3.4.5 N-Species ...... 52 2.3.4.6 Total C, Total N, and C: N Ratio ...... 55 2.3.4.7 Mehlich III available nutrients ...... 56 2.3.5 Data Analysis and Justification ...... 57 2.4 Results of Analysis ...... 57 2.4.1 Trends across the chronosequence ...... 57

2.4.2 Soil pH (H2O) ...... 60 2.4.3 Soil pH (NaF) ...... 63 2.4.4 P-Retention ...... 65

2.4.5 Nitrite (NO2-N), Nitrate (NO3-N), and Ammonium (NH4-N) availability ...... 69 + 2.4.5.1 Ammonium (NH4 ) availability ...... 69

2.4.5.2 Nitrate (NO3-N) and Nitrite (NO2-N) Availability ...... 71 2.4.6 Total N (%), Total SOC (%), and C: N Ratio ...... 74 2.4.6.1 Total N ...... 74 2.4.6.2 Total SOC ...... 77 2.4.6.3 C: N Ratio ...... 79 2.4.7 Mehlich III bio-availability of nutrients ...... 80 2.4.7.1 Macro-nutrients ...... 80 2.4.7.2 Micro-nutrients ...... 86 2.5 References ...... 96 Chapter 3. DISCUSSION OF RESULTS FROM THE BREIDAMERKURJOKULL GLACIAL FORE-FIELD ...... 101 3.1 Introduction to discussion of results ...... 101 3.2 Trends across the moraine chronosequence ...... 103 3.3 Trends across the bird hummocks chronosequence ...... 108 3.4 Comparing the moraines and hummocks ...... 114 3.5 Limitations of study and areas of further investigation ...... 96 3.6 Final statements ...... 119 3.7 References ...... 120 Bibliography ...... 124 Appendix: Abbreviations ...... 135

List of Tables

Table 1.1 Properties selected for soil morphology and profile description for moraines.. 27 Table 1.2 Soil morphology and profile descriptions from bird hummocks found on the moraines ...... 28 Table 2.1 Bird species information of common seabirds taken from INH (2017)...... 44 Table 2.2 Preparation of working stocks for P-retention solution using 50-ml or 25-ml volumetric flasks...... 51 Table 2.3 NH4-N working standards used in calibration curve for determining ammonium...... 53 Table 2.4 Concentrations used of the NO3-N and NO2-N stocks for working standards used in developing calibration curves...... 54 Table 2.5 ANOVA data table of p-values for each one-way ANOVA analysis over moraines, hummocks and woodlands...... 59 Table 2.6 Data table of means, standard deviation and Tukey grouping from one-way ANOVA testing the effect of treatment at each age-group...... 62 Table 2.7 Data table of means, standard deviations and Tukey pairwise comparison group letters pertaining to soil pHNaF...... 64 Table 2.8 Data table of moraines and hummocks P-retention measurements at different age-groups and both depths for hummocks...... 66 Table 2.9 Data table of average ammonium concentration at different age-groups and by depth, with standard deviation in parentheses...... 70 Table 2.10 Data table of average nitrate and nitrite concentrations available at different age-groups and by depth...... 73 Table 2.11 Data table of average total N, total C and C: N ratio values at different age- groups and by depth, with standard deviation in parentheses...... 76 Table 2.12 Data table of bio-available concentration of Ca, K, Mg, and P in the soil. .... 82 Table 2.13 Data table of bio-available concentration of Al, Fe, Na, and S in the soil. .... 89 Table 2.14 Data table of bio-available concentration of B, Cu, Mn, Mo, and Zn in the soil...... 90

List of Figures

Figure 1.1 Map of Iceland with topography, places and Breiðamerkurjökull glacier an outlet glacier of the larger glacier of Vatnajökull in southeastern Iceland ...... 5 Figure 1.2 Bird hummock site sampled at the 1945 moraine. The hummock has a completely different appearance and vegetation cover than the surrounding moraine soils...... 19 Figure 1.3 Study area at Breiðamerkurjökull...... 23 Figure 1.4 Foreland of at Breiðamerkurjökull glacier, taken from the top of the 1960 moraine ridge ...... 24 Figure 1.5 Site comparison of 1960 age-group, the top two photos are a moraine site sampled, and the bottom two photos are from the hummock at that moraine ...... 25 Figure 1.6 Moraine at year 1982 facing the south-east towards Jökulsárlón, the ridge is composed of rocks of various sizes assorted randomly………………………...... 26 Figure 2.1 Map of Vatnajökull National Park and its outlet glaciers, including Breiðamerkurjökull glacier in the south-east. …………………………………………………….…………………. 43 Figure 2.2 Study area at Breiðamerkurjökull…………………………………………………..…47 Figure 2.3 Images of procedure for sampling at an 1890 bird hummock. ……………………….49 Figure 2.4 Model of three different N components have different combination of reagents and solutions ……………. …………………………………………………………………………...55 Figure 2.5 Bar graph of the means and quartiles for each treatment group in the chronosequence.………………………………………………………………………………….61 Figure 2.6 Bar graph of pHNaF means from age-groups measured across the chronosequence, with linear regression lines for relationship between time and pHNaF...... 65 Figure 2.7 Bar graph of the percent P-retention in the moraines and hummocks measured. The plot shows the trends of group averages over time………………………………………………68 Figure 2.8 Bar graph of means from the groups, and standard deviation bars for TN...... 74 Figure 2.9 Bar graph displaying the means of SOC at different age-groups, groups and depths……………………………………………………………………………...……………...78 Figure 3.1 Image of 1960 moraine sampled from 0 – 5 cm, showing course large rocks..……..104 Figure 3.2 Images from Breiðamerkurjökull hummocks, eggshells (left) were at the 1890 site, and feathers (right) observed at the 1982 site ……………….……...……………………………… 109 Figure 3.3 Image of the 1982 hummock profile sampled at Breiðamerkurjökull ………………110

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Chapter 1. INTRODUCTION

1.1 Climate Change in Iceland

The various components that comprise and balance the natural system of the Earth are under increased pressure and have been altered in many ways. Throughout the history of the Earth’s climates, there has been fluctuations of periods of cooling or glaciation, and warming (Mann and

Kump, 2008). However the increased release of greenhouse gases, during a period considered the

Anthropocene, during which humans have fundamentally changed the plant through modification of the Earth’s natural systems. Climate change can be identified by the changes in the mean and/or the variability of its properties, such as the composition of the global atmosphere, and that persists for an extended period, typically decades or longer, whether due to natural variability or as a result of human activity. Temperature data from the atmosphere, the land surface and ocean, combined with indicators such as melting snow, ice and frozen-ground, rising sea levels, changes in plant and animal behavior provide evidence that the Earth’s surface is warming (Mann and

Krump, 2008).

The most severe temperature increases appear to be concentrated in the Arctic and over the

Antarctic latitudes, which respond more rapidly and are valuable indicators of climate change

(Thompson, 2010). The Arctic region will continue to warm more rapidly than the global mean, and potential risks for ecosystems, for health and well-being, and unprecedented challenges, especially from the rate of change (IPCC, 2013). The IPCC summary for policy makers (2013) concluded that the annual mean Arctic sea-ice extent decreased over the period from 1979 to

2012, and has decreased in every season and in every successive decade since 1979. Ice caps and 1 outlet glaciers in Iceland have experienced volume and area changes since the end of the 19th century (Guðmundsson, 2014), many of Iceland’s glaciers have been in a period of recession.

The climate in Iceland is influenced by the atmospheric circulation of the North Atlantic and the oceanic boundaries defined by the warm Irminger current and the cold East Greenland current

(e.g. Einarsson, 1984). The distribution of glaciers on Iceland’s landscape reflects topography, temperatures and precipitation; glaciers form where the mean annual temperatures are below 0º C and where the winter snow exceeds the summer melt. The rainfall regime of Iceland ranges from arid (<400 mm yr-1) to very humid (>2000 mm yr-1), with a substantial proportion of the precipitation falling as snow in winter, especially in the highlands (Gisladóttir et al., 2005).

Approximately 20 km to the south-west of the foreland, the Fagurhólsmýri weather station average annual temperature of 4.79 ⁰C (from unpublished data 1949 – 2008) and average annual precipitation of 150.86 mm (IMO, 2018).

Overall, the glaciers throughout the country are demonstrating a trend of recession, with the greatest extent of the maximum terminus in the Little Ice Age (1890-1920), since the country was settled in the 9th century, currently covering about 11% of Iceland’s total area (Björnsson et al.,

2003). The glaciers started to retreat from their terminal LIA moraines after 1890 and retreated during most of the 20th century, these outlet glaciers halted or advanced slightly in the 1960s–80s due to lower temperatures, but the retreat accelerated after ~2000 (Hannesdóttir et al., 2015).

Another glacier within Vatnajökull ice cap, Skaftafellsjökull glacier started receding from its terminal maximus in 1890, which marks the maximum extent of the glacier (Vilmundardóttir et al., 2014).

Glaciers are an important indicator for climate change around the globe. The presence of ice caps, sheets and glaciers is important to maintaining the earth’s temperature. The melting of snow

2 and ice exposes less reflective surfaces, such as rocks or ocean surface, which absorb more solar radiation, thereby warming even more rapidly (Mann and Krump, 2008). While some debates remain for the finer points of how climate change may interact with ice sheets, the general understanding is that if our planet warms, ice sheets and glaciers will retreat and sea levels will rise as a consequence is not widely contested.

The physical, biological and human systems are all under pressure from climate change. On average, the arctic is warming at twice the rate of the globe as a whole, and the rate of loss of the

West Antarctic and Greenland ice sheets has increased markedly over the last two decades of observation (IPCC, 2013). Another impact of climate change in the Arctic, is the permafrost thaw which can lead to buildings collapse, roadway degradation, coastal erosion and methane release.

There are many direct and indirect consequences on rivers, marine ecosystems, and human settlement in the Polar Regions.

Following retreat in glaciers, material deposits and moraines are dispersed throughout the fore-land, and over time the materials are weathered into more well-developed soils. The moraine material of glacial foreland is a combination of glacial till, and outwash. In these proglacial areas, soils have started to evolve and in the view of climate change, the time factor is important with respect to the landscape and soil development (Egli et. al., 2006). Eruptions throughout the country contribute to the -frequent input of parent materials for the newly formed soils. When the substrate material weathers, there is an increase of geochemical reactivity (Egli et al., 2006). This is an important process for rejuvenating initial soil forming processes and enhancing plant and microbial available nutrients (Dahlgren et. al., 1993). Skaftafellsjökull’s youngest moraines are generally classified as Cryands, Vitric Andosols, Regosols or Leptisols (FAO, 1998;

Vilmundardóttir et al., 2014), and have similar characteristics in the proglacial environment.

1.2 Iceland’s Environment and Volcanism

Iceland is a Nordic island in the northern hemisphere, near the Arctic Circle, Greenland and

Scandinavia (Figure 1.1). The small island is known for its dramatic landscape of volcanoes, geysers, hot springs, lava fields and massive glaciers. The settlement of Iceland began in 874 AD when a Norwegian chieftain became the first permanent settler, and was followed by centuries of

Scandinavians immigrating to the island (McGovern et al., 2007). Humans living in Iceland changed the landscape by deforestation of the woodlands, mostly birch (Betula pubescens), and introduced different animal species to the environment. When the first settlers arrived in Iceland in the ninth century the only native mammal was the arctic fox, and they brought with them sheep, cattle, goats, pigs, horses, as well as cats and dogs (Buckland, 2000; Harlow, 2004). Not only did the first settlers bring mammals to the island, but essentially introduced the environment to different crops, European insects and wild plants, which rapidly transformed some plant communities (McGovern et al., 2007). The deforestation of the landscape by the settlers led to the beginning of soil erosion; the volcanic Andosols of Iceland are very vulnerable to wind and water transport (e.g. Arnalds, 1995; Erlendsson, 2007; Dugmore et al., 2009). Severe land degradation, desertification and soil erosion are considered among the most serious environmental problems in

Iceland (Gísladóttir et al., 2010), often prompted by overgrazing and lack of vegetation cover.

Figure 1.1 Map of Iceland with topography, places and Breiðamerkurjökull glacier an outlet glacier of the larger glacier of Vatnajökull in southeastern Iceland. (Google Earth open source satellite images, 2018).

Volcanic Activity of Iceland

The landscape consists of extremes between glacial land cover and various types of active, subglacial, and dormant volcanoes. This contrast allows for unique geographical and climatic settings for soil development. Iceland is a volcanic island emerged from North-Atlantic

Ridge (Bodvarrson and Walker, 1963), and primarily consisting of igneous rocks of basaltic composition. The islands formation is as the result of a ridge-centered hotspot over the Eurasian and North American tectonic plates (e.g. Bjarnason and Schmeling, 2009; Helgason, 1985). The 5 island is relatively young geologically, with the land mass being formed approximately 20 million years ago, as a result of a volcanic hotspot created by a fissure in the Mid-Atlantic Ridge

(Harðarson and Hjartarson, 2008).

Due to Iceland’s location in the North Atlantic between 63º and 66º and abundant precipitation, many of its volcanoes are capped by glaciers, which thus leads to explosive basaltic eruptions (Larsen and Eiriksson, 2008). As a consequence of the plate movement at the divergent boundary, the country experiences higher influxes of volcanic activity and semi-frequent depositions of tephric materials. Volcanic ash or tephra is commonly unconsolidated, comminuted materaials containing a large quantity of volcanic glass which shows the least resistance to chemical weathering (Shoji et al., 1993). . Historically (the last ~1100 years), 75% of eruptions taking place in Iceland have produced tephra, with four out of every five tephra layers are of basaltic composition (Larsen and Eiriksson, 2008).

Currently, the country’s area of 103,000 km2 is home to between about 30-40 active volcanoes (which have erupted within the last few centuries) (e.g. Thordarson, and Höskuldsson,

2008). The volcanic activity directly impacts the soil properties and development; explosive volcanic eruptions generate the parent material that eventually weathers into a volcanic ash soils –

Andosols (Arnalds, 2004). The term “Ando soil” from the Japanese word for “dark soil” (An; dark: do; soils) (Shoji et al., 1993). The vegetated areas of Iceland are commonly Histosols, many soils of the deserts can be classified as the same according to established classification criteria

(FAO, 1998), but the sandy deserts also contain Leptosols and Regosols (Gisladottir et al., 2005).

These desert soils are also termed Vitrisols according to an Icelandic classification scheme

(Arnalds, 2004), due to their high content of vitric material.

Glaciers of Iceland

Glaciers are a fundamental component of the hydrologic cycle; they act as a storage for massive amount of freshwater around the world. These glaciers, ice caps and ice sheets influence the volume, variability and water quality of runoff; glaciers have a profound impact on the topography in many areas throughout the world. Within the landscape, the glacial movements influence streamflow, water quality and geomorphic characteristics. The volcanic soils are known for their distinctive physical and structural properties of a soil including: higher cation exchange capacity (CEC), variable charge, water holding capacity (WHC), permeability, porosity and hydraulic conductivity.

Additional areas will become ice-free and subject to weathering, soil formation, and ecological succession. The glaciers carve through the landscape as they move, so when the ice melts, rock and debris is deposited in a feature called a moraine. There is a variety of texture classes from clay-sized up through boulders. Since the moraine is commonly bare substrate, minimal plant and microbial life can exist until ecological progression and soil development begins. In the early successional stages, the plant and microbial community composition is mainly determined by the abiotic conditions and local species pool at the site, as well as the landscape features (Harantová et al., 2017).

Primary succession is very slow, and begins where no previous soil existed, which can take several hundred or thousands of years to produce fertile soil naturally, depending on the environmental conditions. Parent rock is an unfavorable substrate for colonization, until it has been weathered by both physical and chemical attack (Wynn-Williams, 1993; Schulz et al.,

2013). Icelandic and other arctic ecosystems demonstrate that N2 fixing moss associated with cyanobacterial communities are important in nutrient cycling (Bernasconi et al., 2008).

Vilmundardóttir et al. (2015) showed that biological crust starts to form in the 18 yr-old moraine of Breiðamerkurjökull, and gradually increases its cover until reaching ~10% after 82 yrs.

When microbes do establish a community, biological weathering can be an important component in rock breakdown (Friedmann, 1982). Other microbial colonists include: phototrophic, chemolithotrophic, and heterotrophic microbes, and chasmolithic communities (i.e. lichens, fungi, algae, and cyanobacteria) (Vestal, 1993). The chemical composition and physical structure of the substrata will also influence the microorganisms present (Schulz et al., 2013).

Microorganisms will have different interactions with the different particle fractions (sand, silt, and clay) of the parent material or substrate. In principal, two main functions can be assigned to the microbes with the initial progressions of soil formation: (i) the biological weathering of the bedrock material and (ii) the formation of interfaces for nutrient turnover at vegetation free sites and developing initial nutrient cycles (e.g. Vestal, 1993; Bernasconi, 2008; Frey et al., 2010). Van

Leeuwen et al. (in review) analyzed the soil development from an ecosystem perspective looking at food web development, vegetation succession and soil ecological processes within the nearby glacial foreland of Skaftafellsjökull. Considering a geoecological approach as a conceptual framework addresses key aspects, (1) the concept that biological and physical systems interact within the evolving glacial foreland and (2) that glacier foreland landscapes are special systems within which the characteristics of succession are generally held constant (Matthews, 1992).

The fore-land exposed by glaciers has numerous inputs of parent materials from moraines, to washout and sediment deposited by glacial rivers. The Icelandic soils are of the Holocene age, due to the aeolian materials, the surface is young, and older sediments are buried under newer tephra deposits. These soils of Iceland are generally regolithic, composed of glacio-fluvial origin, course, gravelly textured, low organic material, and little development of soil horizons. There is a concern for Icelandic soils exposed to erosion because it redistributes the valuable nutrients, such 8 as nitrogen (N), soil organic C (SOC), and phosphorus (P). SOC concentration, along with its quality and dynamics, is essential to diverse soil functions and ecosystem services (Lal, 2016).

Most soil N is found in organic matter, which decomposes to other forms primarily ammonium

(NH4), nitrite (NO2) and nitrate (NO3), when held in organic form (Brady, 1974). Few studies have conducted analyzes of nutrient availability in soils across deglaciated chronosequences of soils. Nutrient availability is often a limiting factor for the succession of plant and microorganisms communities (i.e. Gudmundsson et al., 2014, Castle et al., 2017; Bernasconi et al., 2011). Chemical, biological and physical gradients along glaciers could potentially by influenced in the coming decades by the pressures from climate change.

1.3 History of land use management of soils in Iceland

With the settlement of the ninth century, the human activity was unknowingly altering the ecosystem of the small island. It is estimated that 90 percent of the forest and 40 percent of the soil present at the ninth century has disappeared, and 73 percent of the modern land surface is currently affected by soil erosion (Arnalds et al., 1995). The term soil erosion is used for surface areas where land degradation has resulted in the depletion of vegetation, followed by active soil movement (Gísladóttir, 2001). In response to severe land degradation and desertification that was threatening the existence of several communities, an organized soil conservation group was founded in 1907, the Soil Conservation Service of Iceland (SCSI) (Arnalds and Runolfsson,

2009; Arnalds, 2001).

The initial decades of soil conservation were devoted to urgently halting the continuation of sand dunes and other forms of desertification in both pastures and rangelands. There were a series of problems that prevented soil conservation programs from being effective in attaining the overall goals, among the most concerning being the top-down approach without much input from people living in affected areas. Land users must recognize the effects that their actions have; and 9 their responsibility must also be clear, however, such awareness requires a thorough understanding of ecosystems, land-use effects, and means to restore the damaged land (Arnalds,

2004). The pressures from human-induced climate change presented new incentives for the soil conservation and forestry in Iceland. The degradation and desertification of soils in Iceland has depleted the SOC, and there is a strong interest in restoring these soils and ecosystems in order to sequester C (Lal, 2009). The Soil Conservation Plan (2003 – 2014) also set goals for mitigation of land degradation and desertification, by establishing a new land care incentives program and adapting sustainable land use practices (The Icelandic Government, 2003). Present day restoration efforts are also focused upon: increasing the diversity of species and habitats, placing greater emphasis on landowners’ and farmers’ responsibilities, strengthening the resilience of ecosystems that are prone to volcanic deposition or glacial flooding, and continuing to stabilize encroaching sand (Arnalds, 2004; Aradóttir et al., 2013; Brenner, 2016).

Various properties of Andosols have important implications for erosion, including the volcanic parent materials, which have high surface area and weather rapidly to form allophane, imogolite, and poorly crystalized ferrihydrite (Wada, 1985). The loss of vegetation further increases the soil’s susceptibility to erosion; increases in wind transport, and direct disturbance of areas can extend beyond those initially disturbed (Gisladóttir et al., 2005). Wind erosion is a dominant process in the relatively dry areas of northeast Iceland, while water erosion is more dominant in southern Iceland (Arnalds, 2010). With the depletion of vegetation cover, the soils are more susceptible to soil erosion (Gísladóttir, 2001). The uplands and lowland regions demonstrate different models of change in the plant communities and effects of soil erosion, these are complex interactions between natural environmental processes and human activities

(Dugmore et al., 2009). Arnalds (2015) presents a review of the interrelated problems contributing to the land degradation and desertification, and the factors affecting the success of

10 different reclamation approaches. In conclusion, the land-management decisions have played an important role in triggering changes in the soil degradation, as well as, the effects due to changes in climate.

1.4 Classification of Soils in Iceland

Among the soils around the world, Icelandic soils are especially unique due to the soil environment and conditions in which they form. Soils of Iceland mostly develop in parent materials of volcanic origin, including tephra, ash and larger rocks formed originally from either effusive or eruptive volcanic activity. There are three main groups identified in Iceland:

Andosols, Histosols, and Vitrisols (Arnalds, 2004); however, there are a variety of other types, but have limited extent. The Histosols are distributed predominantly in the wetland soils and are largely be organic with >20% C (Arnalds, 2008b) and minerogenic content facilitates the ability of histosols to bind nutrients. (Möckel et al., 2017). The Vitrisols are the soils of the deserts, which are dominated by poorly weathered volcanic tephra and volcanic glass. These have limited amount of organic C (<1%) and are overall infertile in contrast to the other soil types distributed through Iceland. The Andosols are the majority of Icelandic soils, and are divided into a few specific types: Brown Andosol, Organic Andosol, Vitric Andosol, Leptosols, and Sandy

Andosola in accordance to the classification of FAO-WRB (Arnalds, 2008a).

Active eolian processes, frequent tephra deposition events, and a sub-arctic climate with frequent freeze-thaw cycles greatly modify the soils of Iceland (Arnalds, 2008b). This eolian activity has dominated influence on soil formation in Iceland. Andosols are highly porous, dark- coloured soils developed from parent material of volcanic origin, such as volcanic ash, tuff, and pumice (FAO, 1998), and have a worldwide extent estimated less than 1 percent of the total soil area on Earth. Thus, these soils are found around active volcanic areas and exhibit unique soil properties due to their location and parent material (Arnalds, 2008a). The proposal outlined 11 several important criteria necessary to reclassify volcanic ash soils (Shoji et al., 1993). Andosols exhibit characteristic properties of soils dominated by andic materials, including allophane contents up to 30%, and ferrihydrite accounting for 5-15% of the soil (Arnalds, 2004). The central concept behind classifying this order of soil is that of a soil developing in volcanic ash, pumice, cinders, and other volcanic ejecta, and dominated by noncrystalline materials

Andosols are the soils of active volcanic regions and described by Dudal (et al., 1983) including those of: Europe, Africa, Indian Ocean, North and South America, eastern Asia and the

Pacific. However, the estimates do not include the Andosols of Iceland, which make up the largest distribution of Europe and potentially >5% of all Andosols in the world (Arnalds, 2004).

There are a variety of Andosols throughout the world, however, reviews of Icelandic soils are few and limited in scope. Their parent material is the most defining feature, most commonly tephra, the collective term for volcanic ejecta of varying morphology, size and composition. Icelandic

Andosols often contain tephra layers, rhyolitic layers are fewer in number than basalt, but have a distinctive light color in contrast to the darkish brown soil color (Arnalds, 2008b). Among these characteristics, low bulk density, rapid hydraulic conductivity and infiltration (Dahlgren et al.,

2004), high WHC, natural tendency to accumulate C (Nanzyo, 2002), tendency to immobilize P

(Gudmundsson et al., 2005), and considered fertile soils.

1.5 Soil Forming Factors in Glacial Moraines

Soil chronosequences are valuable tools for investigating rates and direction of soil and landscape evolution, and often found in different landscapes including: sand dunes, glacial moraines, lava flows, alluvial fans, river terraces etc. (Huggett, 1998). The concept of a chronosequence was systemized by Hans Jenny (1941) in the context of soil development, where the soil as a whole is a function of the soil forming factors: climate, available biota, topography, parent material, time, and people. The transformation of rock into soil is designated as soil 12 formation (Jenny, 1941), and that many important properties of soils are inherited from the underlying parent material.

This study is focused on soil development where time is the dominant soil forming factor, but with consideration of point-centered available biota (seabirds). Time as a soil forming factor is the estimating of relative age or degree of maturity of soils is universally based on horizon differentiation (Jenny, 1941). Global climate change is accelerating ice melt of glaciers, ice sheets and caps around the world. Therefore, as glaciers continue to melt, new surfaces and materials will be exposed to soil forming processes. The chronosequence concept can be defined by a set of sites formed from the same parent material or substrate that differs in the time since they were formed (Walker et al., 2010). Soil chronosequences are genetically related suites of soils evolved under similar conditions of vegetation, topography, and climate. Chronosequences are found in many landscapes including sand dunes, glacial moraines, landslide scars, old pasture, old mining areas, lava flows, alluvial flans, flood plains, and terraces. Using this approach has the advantage of translating spatial differences between soils into temporal differences. When the chronosequences are interpreted as a series of soils of different ages that formed on the same parent material, and can be highly appropriate for addressing questions about soil development

(Walker et al., 2010). This method has also advanced understanding of how soil nutrients change during pedogenesis (Walker and Syers, 1976).

The soil is an exceedingly complex system possessing a great number of properties, processes and connections. These elements have provided a strong framework for theories and approaches to understanding soil genesis research. The soil forming factor equation recognizes each measure as independent variables, and it serves to simplify complex relations involved with soil development. Furthermore, this equation has become a common concept in pedology (Bockheim et al., 2014). Jacobson and Birks (1980) analyzed the glacial moraines over nine chemical 13 variables, including organic matter, pH, and SOC from the moraines of the Klutlan glacier, where organic matter increases rapidly for the first 100 to 150 years, soil pH falls from 8.0 to 6.0 and N levels in the mineral soil increases to 0.7% N from 0.14% N, after 175 to 200 years. Other studies have been done with the vegetation succession on a chronosequence in glacial moraines,

Vilmundardóttir et al. (2014; 2015), Walker et al. (2010) and Crocker and Major (1950) evaluated this method to study ecological succession and soil development. Huggett (1998) concluded that soil chronosequences are still potent instruments for pedological investigations and they play an important role in testing pedogenesis.

Perhaps the most emphasized soil forming factor is soil climate, stressing the importance of soil temperature and moisture conditions. Generally, soil development proceeds more rapidly in warm and wet climates, or slowly in cold and dry climate where weathering is impeded and takes much longer (e.g. Marbut, 1935; Hilgard, 1882). The soil forming factor climate is multifaceted and is difficult to represent in a single numerical value. In order to quantify climate, it is necessary to work with individual climatic components, the most important of which are moisture and temperature.

These variables play a major role in shaping the microbial community of the soil, vegetation, soil aggregation, movement of gas and water, rate of weathering and mineralization, essentially climatic influences dominate the soil formation picture (Brady, 1974). Temperature and precipitation can be major drivers of the weathering processes for parent material. In the case of Andosols, rates of chemical weathering in tephra are often determined by the quantity of clay, as well as the concentration of acid oxalate extractable Al (Shoji et al., 1993). Weathering is a term which describes all physical and chemical changes produced in substrate, at or near the earth’s surface, by atmospheric agents (Brady, 1974), and biological weathering. The parent material is broken down at the Earth’s surface into particles (sand, silt, clay) and under various 14 mechanisms form aggregates. Soil microbes play an essential role in the newly-formed environment by contributing to the release of key nutrients from primary minerals required not only for their own nutrition, but also for that of plants (Hodkinson et al., 2003). However, the roles of biota and the factors that regulate the community structure and activities will vary from soil to soil.

The parent material aspect of the soil is important for the weathering process, soil formation, and development rates. Parent material, mineralogy, structure, and climate primarily control weathering rates. Weathering rates are rapid in high-porosity and high-permeability rocks. Tephra weathers rapidly and results in higher concentrations of Al, Fe, and Si, which crystallize into

Allophane, Imogolite and Ferrihydritie (Shoji et al., 1993). The parent materials of Icelandic soils include tephra layers and Aeolian sediments consisting mostly of volcanic glass. The volcanic activity creates materials that have a dominating influence on the soil environment.

Soils of Iceland are considered unique among volcanic soils described in the literature, because not only are they young, but also receive large inputs of Aeolian materials, specifically of basaltic origins. These soils are also formed at lower temperatures, with freeze and thaw cycles, and a wide range of precipitation depending on the location in the country. Breiðamerkurjökull glacial fore-field is located near to the ocean, which maintains a mild climate with average annual temperature (1961-1990) at 4.6ºC and ample precipitation throughout the year with ample average precipitation. This location is also influenced by the annual presence of seabirds of the

Breiðamerkursandur. The biotic factor is a variable that incorporates pedologically important groups of organisms, namely, microbes, vegetation, animals, and humans. Seabirds have the capacity to drastically transform the environmental conditions of the sites where they establish their breeding colonies via soil (Otero et al., 2018).

1.6 Study Rationale

The modeled winter balance (from 1890 to 2010) of Icelandic glaciers demonstrated a strongly negative mass loss since the 1930s, according to a mass balance model calibrated with annual field measurements over the last two decades (Björnsson et al., 2013). These changes in glacier mass have numerous environmental impacts, one being the recession of glaciers and ice caps. Among the main Icelandic ice caps, the annual net mass balance of Vatnajökull has remained negative from since 1995, with some variation of inland glaciers (Björnsson et al.,

2013). This general mass loss can be attributed to the higher summer temperatures, longer melting seasons, warm winters reducing precipitation falling as snow, and exposure of low- albedo glacier ice. If the current climate change trends continue into the future, the glaciers are predicted to lose approximately 20 – 30% of their volume, depending on their elevation range

(Aðalgeirsdóttir et al., 2011), and completely disappear within 100 – 200 years.

Furthermore, as glaciers recede, the opportunity to study the initial soil forming processes of postglacial moraine soils is possible. Not only does the changing climate play a role in glacier recession, but influences the rate of soil development. A glacial fore-field is a dynamic and variable landscape, in which glacial waters are interacting with the surfaces exposed. Various glacial chronosequences studies allow understanding of the processes involved in the rapid weathering that occurs post-glacial retreat (e.g. Huggett, 1998; Dahlgren et al., 2004; Egli et al.,

2006). Vilmundardóttir et al. (2014) discusses the trends of early stage development along the moraines of Skaftafellsjökull glacier, showing the changes after 120 years of soil formation. This study and the Breiðamerkurjökull study (Vilmundardóttir et al., 2015) present data supporting the deglaciated terrains’ plant succession and soil evolution. Iceland has a large amount of surface area which is ice-covered and potentially susceptible to increases in ice-loss over the next couple

16 centuries. However, there has been limited research conducted on the early stages of soil formation in postglacial areas of Iceland.

Not only are these areas postglacial moraine soils, but they are predominantly Andosols.

Volcanic soils have distinct morphological, physical, chemical and biological characteristics, but there are fewer studies contributing to the whole on soil science than other soil types. This could also be explained due to the distribution of volcanic soils, cover about 1.9% of the terrestrial surface, store about 4.9% of the Earth's C (Eswaran et al., 1992). Additionally, Icelandic soils are different from most soils throughout Europe due to the volcanic material and being situated in the climatically sensitive boundary between polar and mid-latitude atmospheric circulation

(Björnsson et al., 2013). Data from Icelandic soils have not been commonly included in general reviews of Andosols (e.g. Shoji et al., 1993), with exception to a chapter by Kimble et al. (1998) in the Handbook of Soil Science (Sumner, 1998). There is also limited research specifically pertaining to the trends of chemical properties in early stage soil development. The literature demonstrates a generally developed understanding of SOC accretion and storage (Kabala and

Zapart, 2012; Vilmundardóttir et al., 2014), but other macro- and micronutrients trends are not researched in-depth. Some studies on alpine glaciers focus on the transformations of N and P over the glacial chronosequence (i.e. D’Amico et al., 2014; Perez et al., 2014).

Within the studies conducted on nutrient dynamics, even fewer pertain to the relationship of biotic factors with evolution of soil chemical properties. Seabirds provide organic inputs throughout the fore-field at Breiðamerkurjökull by using the area for roosting and nesting purposes. Vilmundardóttir et al. (2015) presented evidence of significant differences between the bird hummocks and the surrounding moraine soils. Lund-Hansen and Lange (1991) observed that the Breiðamerkursandur (63°52’N, 16°29W) is predominantly used by the Great Skua

(Stercorarius skua) and Arctic Skua (Stercorarius parasiticus). Among the bird species 17 monitored in Iceland, the Arctic Skua and Great Skua, are less commonly studied and information on population changes is minimal. The Great Skua is a northern hemisphere seabird breeding in regions ranging from Iceland and Faeroes to Scotland, and Norway.

There are approximately 5,400 breeding pairs in Iceland, with approximately 80% of the breeding population and the greatest density at Skeiðarásandur, Öræfi and Breiðamerkursandur

(Lund-Hansen and Lange, 1991). Figure 1.2 is an example of a hummock formed in the presence of the seabirds. Soil properties of the bird hummocks were different from the surrounding moraines, and are roughly defined by the accumulation of droppings where birds regularly perch and defecate (Vilmundardóttir et al., 2015). The hummock vegetation differed from the adjacent soils, as they were fully covered by thick and diverse grasses and herbs. The seabird’s organic inputs potentially act as a fertilizer and stimulant for plant and soil development (Otero et al.,

2018), however, establishing vegetation in the soil could be the significant difference in the rate of soil development. After 30 years in the Skaftafell foreland, vegetation cover increases significantly from a small pioneer vegetation with a cover of 7% (van Leeuwen et al., in review), and is important to accumulating wind-blown material within the soil profile (Vilmundardóttir et al., 2014). The establishment of vegetation presents the question whether the hummock soils are developed under accumulation processes, or deposition and weathering. Arnalds (2000; 2008b) identified that active eolian processes lead to steady flux of materials that are deposited to the surface of existing soils at a rate of <0.001 to >1 mm year -1, which modifies the soil environment by recharging the system with fresh parent material. This is an important consideration when analyzing the results of the moraine and hummock chronosequence at

Breiðamerkurjökull.

Figure 1.2 Bird hummock site sampled at the 1945 moraine (Turner, 2017). The hummock has a completely different appearance and vegetation cover than the surrounding moraine soils.

Many studies that utilize a glacial chronosequence, predominately look at vegetation and microbial succession, as well as changes in the pedology with time. The literature on soil chemical properties over time is a thematic area that needs to be strengthened. Understanding chemical, mineralogy, and nutrient dynamics can strengthen the understanding of the processes of soil formation on exposed moraines. This provides information over how to restore degraded soils in Iceland, connecting beneficial ecosystem services and agriculture, such as water quality, offsetting the harmful GHG emissions, and improving soil physical properties. With

19 consideration of the limits of research conducted in this area, a glacial chronosequence study was established by Vilmundarttir et al., (2015) during cooperation between the University of Iceland and the Ohio State University. This study collected samples from the fore-field of

Breiðamerkurjökull glacier in both moraines and bird hummocks across age groups from 1890 to

2012.

This experiment was the basis for this thesis, which specifically is aimed to report on the soil development on moraines and hummock soils. The chronosquence of soil exposure provides valuable data in which to draw conclusions, focusing on nutrient and chemical property trends in early soil formation. The focus of this study seeks to build on the record of data and measurements conducted over the 127 year chronosequence. Previous analysis done by

Vilmundardóttir (et al., 2015) combined with this thesis evaluation contributes to a more comprehensive assessment of the soil development and vegetation succession at this study site.

The objectives of the study are focused on the deglaciated terrain and how is that environment evolving over time and exposure to the soil forming factors.

1.7 Study Area

The site used in this study is within the glacial fore-field of an outlet glacier flowing south from the Vatnajökull ice-cap located in southeast Iceland. Breiðamerkurjökull is an outlet glacier on the south side of Vatnajökull in southeast Iceland, approximately 80 km west of Höfn

(Figure 1.1). The site lies within the pro-glacial area (N64°05′−64°02′, W16°18′−16°14′)

(Vilmundardóttir et al., 2015) and is confined between the two medial moraines Máfabyggðarönd to the west and Esjufjallarönd and Jökulsárlón glacial lake to the east. The proglacial area of

Breiðamerkurjökull consists of two main parts. The area beyond the limit of the last re-advance of the glacier (that is the 1890, moraine) consists of sandar (outwash plane), which descend from 30 m at their proximal margins to sea-level. Over the ~120 years that Breiðamerkurjökull receded, 20 the glacier terminus retreated 4–7 km, and a land area of ∼115 km2 (0.95 km2 a−1) was exposed

(Guðmundsson et al., 2017). The second area is inside the 1890 moraine, the landscape consists of till plains, moraine ridges, small sandar, eskers, kame and kettle topography, lake basins and meltwater channels (Price, 1969).

The study area of this thesis focuses on the region inside the 1890 moraine considered the outwash plane (Figure 1.3). The glaciers movements have produced a very impressive suite of moraine ridges during its retreat from the maximum extent in the late nineteenth century. All of the moraine ridges consist of rounded volcanic fragments ranging in size from clay to boulders.

The material forming most of the moraine ridges is therefore mainly gravel with some fine material acting as a rather weak matrix for aggregation. Vilmundardóttir et al. (2015) conducted profile descriptions for the each moraine investigated identifying textures including: sand, fine sand, loamy sand, sandy loam and silt loam. The horizons of moraines develop initially C (2012),

C1-C2 (1994), AC-C (in both 1982 and 1960), A-C, (in both 1945 and 1930), and A-C1-C2

(1890) with varying profile depths (Vilmundardóttir et al., 2015), and the birch woodland reference area A-A2-Bw horizons.

Fieldwork at Breiðamerkurjökull was conducted in the summer months and included moraines exposed in 2012 (closest to front of the glacier), 2004, 1994, 1982, 1960 1945, 1930, and 1890, the furthest extend of the moraines (Figure 1.3). The sampling sites were restricted to the end or ground moraines with an estimated time of deposition, as well as, sampling sites are well drained and without signs of disturbance. The sites excluded depressions/toe-slope positons

(Vilmundardóttir et al., 2015) to avoid sites of considerable sediment deposition. Hummock sampling sites were kept to the same standards as the moraines, however they are distinctly different due to vegetation and where the seabird’s presence is observed by the hummock formation (Fig. 1.2). 21

Sampling sites crossed the foreland laterally from the edge of Jökulsárlón glacial lake to the east, to the west spread from ~0.5 to ~2 km (Fig. 1.3). Five random points were chosen for sampling moraines (1890 to 2004, only 3 taken at 2012) within 0.25 m2 quadrant (seen in Fig.

1.2), and three random points were selected for bird hummocks. The moraines profile is shallow and could only be sampled to a depth of 0 – 5 cm (Fig. 1.5), the material consisted of fine roots, course rocks and fine glassy material. However, the hummocks have accumulated enough material to be sampled up to 15 cm, specifically divided at 0 – 5 cm samples and 5 – 15 cm. Fig.

1.6 presents a visual comparison of the profiles of a moraine site and a hummock from the same age group. Finally, soil samples were collected in birch woodlands at Stórihnaus (the reference or baseline area), which is approximately 11 km southwest of Breiðamerkurjökull outwash plane

(Fig. 1.3). Three sites were sampled at this location, and were sampled at the two depths (0-5 cm,

5-15 cm) to provide a reference comparison for both moraines and hummocks. Hummocks were not sampled from the most recent moraines, 2004 and 2012, there was not a distinctive hummock formation developed at those moraines. In total 38 moraines, 36 bird hummocks, and 6 woodland samples were collected for analysis and stored at the University of Iceland, Reykjavik. Bulk samples were obtained from sites in plastic bags, the larger rocks were removed in the field, and smaller rocks and large roots were removed prior to sieving. The bulk samples were then air- dried, gently crushed by hand, and sieved through 2 mm for majority of analysis, as well as ball milled at 150 μm for the C and N analysis.

Figure 1.3 Study area at Breiðamerkurjökull. The lines demonstrate the glaciers position at different years including: 1890, 1930, 1945, 1960, 1982, 1994, 2004 and 2012, which were redrawn from S. Guðmundsson (2014) and O. K. Vilmundardóttir via personal communication and collaboration. The black points mark soil sampling sites collected in 2012, and green stars mark sampling sites of the bird hummocks collected in 2017. The landscapes distribution of lakes and rivers are based on aerial photography in summer of 2013. G, B, K and Ӧ mark the location of Grímsvötn, Bárðarbunga, Katla and Ӧræfajökull subglacial volcanoes.

Figure 1.4 Foreland of at Breiðamerkurjökull glacier, taken from the top of the 1960 moraine ridge. The front of the terminus is lined by the black rock in the left side, with the glacier flowing into the Jökulsárlón glacial lagoon. There are braided rivers throughout the landscape with generally short grasses, mosses and lichens for vegetation (Turner, 2017).

Historical records have provided insight into the multiple phases of retreat and advance of the glacier. The proglacial area has been the subject of detailed study by the Department of

Geography, University of Glasgow, from 1964 to 1968 (Price, 1969); aerial photography has been recorded at different times of the surface area. The rocks of the region are basaltic tephra, weathering rates in Iceland are under a generally dry, cold climate (Arnalds, 2008b); both allophane and ferrihydrate are common in the Icelandic soils (imogolite is a minor constituent), with clay contents usually ranging between 10 and 35%. Price (1969) concluded that, prior to the 24 last advance of the glacier, the proglacial area was similar to the present proglacial area which is dominated by sandar consisting of fluvioglacial sands and gravels.

Figure 1.5 Site comparison of 1960 age-group, the top two photos are a moraine site sampled, and the bottom two photos are from the hummock at that moraine (Turner, 2017). The profiles are based on the descriptions provided by Vilmundardóttir et al. (2015).

Figure 1.6 Moraine at year 1982 facing towards the south-east towards Jökulsárlón, the ridge is composed of rocks of various sizes assorted randomly (Turner, 2017).

Table 1.1 Properties selected for soil morphology and profile description for moraines. Horizon Depth (cm) Texture* Tephra Layers (moraines) 2012 C >0 ls 2004 C1 0 – 3 s C2 >3 sl 1994 C1 0 – 3 s C2 >3 sl 1982 AC 0 – 4 sl C >4 ls 1960 AC 0 – 2 fs C >2 s 1945 A 0 – 1 sl C >1 sl 1930 A 0 – 1.5 sl C >1 sl 1890 A 0 – 2.5 ls C1 2.5 – 11 s C2 >11 s Birch Ref. area Woodland (profile B) A 0 – 5 sl Grímsvötn 2011 tephra, 1 cm thick, in sward layer. A2 5 – 11 sl Bw 30 - unknown sl Three dark colored tephra bands, two 0.5 cm and one 2 cm thick. Profile descriptions (i.e. Horizons, Depth, Texture, and Tephra) adapted from Vilmundardóttir et al. (2015), terminology is from Schoenberger et al. (2002). Texture — s, sand; fs, fine sand; ls, loamy sand; sl, sandy loam; sil, silt loam. ⁎Texture was estimated by feel on the fine earth fraction. Gravel content (% volume) could be estimated to range between being gravelly (15–35%) and very gravelly (35–60%) with an exception in the 1890 moraine where it was <15%. The woodland soils were gravel free.

Table 1.2 Soil morphology and profile descriptions from bird hummocks found on the moraines. Horizon Depth (cm) Texture* Tephra Layers (moraines) 1994 A 0 – 11 s Grímsvötn 2011 tephra C >11 ne 1982 A 0 – 6 ls C >6 ls 1960 A 0 – 3 sl Grímsvötn 2011 tephra C >3 ne 1945 O 0 – 7 sl Grímsvötn 2011 tephra C >7 ne 1930 A1 0 – 2.5 ls A2 2.5 – 9 s C >9 ne 1890 A1 0 – 4 sl Grímsvötn 2011 tephra A2 4 – 14 ls C >14 ne Profile descriptions (i.e. Horizons, Depth, Texture, and Tephra) from Vilmundardóttir et al. (2015), terminology is from Schoenberger et al. (2002). Texture — s, sand; ls, loamy sand; sl, sandy loam, ne – depth not evaluated. *Texture was estimated by feel on the fine earth fraction, gravel content not estimated.

1.8 Hypotheses

Among the vegetation in Iceland, few plants have the capacity to make use of atmospheric N, therefore N accumulation in the soil is a slow process. N is a key element in the various biogeochemical processes, and is often a limitation to the growth of microorganisms and many plants of glacial chronosequences (Göransson et al., 2011). However, the TN gradually increases in the moraines at Breiðamerkurjökull over time (Vilmundardóttir et al., 2015a), and is relatively low in moraine soils outside of the bird hummocks. This could indicate that the birds are changing the concentrations of various nutrients. Mineralization is the process by which 28 microbes decompose organic N from manure, organic matter and crop residues to ammonia then

+ ammonium (NH4 ) (Brady, 1974). Nitrification is the process by which microorganisms convert

+ - - - NH4 to nitrite (NO2 ) then nitrate (NO3 ) to obtain energy, however NO3 is the most plant available form of N, and is also highly susceptible to leaching losses (Johnson et al., 2005).

Currently, the plant available portion of the TN in the soils of Breiðamerkurjökull is

+ - - unknown. A chronosequence is beneficial in understanding how forms of N (NH4 , NO3 , NO2 ) change over time, this is also relevant to vegetation succession and food web trends (van

Leeuwen et al., in review). The available P and P-retention, as well as the series of Mehlich micro- and macronutrients, are also unknown across the chronosequence, so they will be included in the chemical variables analyzed in the soil and bird hummocks. The Mehlich III (1984) method was selected due to its use with other volcanic soils, having higher concentrations of extracted nutrients when compared to the Bray-1 method (Michaelson et al., 1987).

The proposed study is focused on two main research questions: 1.) How are nutrient and chemical properties developing in glacial moraine soils, with increasing age of moraine and exposure to soil forming factors? and 2.) will the nutrient and chemical trends measured in the glacial moraine soils be similar to the concentrations measured in the bird hummocks? The study is designed to test the following two hypotheses:

Hypothesis 1. The concentrations of plant available nutrients will be very low or undetectable in the moraine soils without the input of biota (seabirds).

Rationale: The previous study done at this study site observed that the TN concentration was almost zero in the youngest three moraine groups. However, the concentration of TN between

1890 and 1982 ranged from 0.006% to 0.045%, peaking in 1930 at 0.071% (Vilmundardóttir et al., 2015a). Brenner (2016) observed that the concentration of NH4 and P in the volcanic soils

29 were very low, and those of the nitrite and nitrate were below the limit of detection (LOD = 0.03 mg NO2-N/kg soil and 0.69 mg NO3-N/kg soil). Therefore their precise concentrations are unknown and negligible. The soils were low in C, have low water retention and classified as

Andosols (FAO, 1998) and have a texture of sandy loam/loamy sand with gravelly surface layers due to the winter frost heaves.

Hypothesis 2. The point-centered presence of seabirds will have some significant impact on a.) soil development (related to horizonation and structure development) and b.) increases the overall concentrations of plant available nutrients, when compared to the moraine soils.

Rationale: Several studies over bird hummocks and the droppings inputs on soils demonstrate that the top 0-5 cm layer has an overall higher concentrations of plant available nutrients than that in the sub-soil layers. The previous study at Breiðamerkurjökull, has shown that TN ranged from

0.087% (1994) to a peak at 1.113% (1945), and then declined to 0.395% (1890) (Vilmundardóttir et al., 2015a). Verbeek and Boasson (1984) studied the impacts bird life on soil hummocks in the

Pyrenees, and reported significantly more available N compared to that in soils of their surroundings.

1.9 Current Study

This thesis study focuses on soil chemical dynamics along a chronosequence of the

Breiðamerkurjökull glacial fore-field. Prior to this study, Vilmundardóttir et al. (2015a) sampled this site with the same experimental design looking at the general soil characteristics and physical properties. The same moraines were utilized in the current study in order to advance upon the previous work and build a robust, multidisciplinary record of data. The glacier chronosequence dataset can continue to be developed over time and documented to draw conclusions about how

30 the landscape changes. Additionally, this soil is using an adjacent birch woodland as a reference ecosystem (Fig. 1.3) that represents into what the glacial fore-field will eventually develop into.

Glacial chronosequences are often described from a single discipline perspective (e.g. ecological succession, microbiology, pedology, hydrology, soil chemistry, biology and physics).

Crocker and Major (1955) used the chronosequence as a linkage between the main phases in vegetation succession and the changes in the soil properties including: bulk density of the fine earth, reaction, SOC, calcium carbonate, and total N (TN). Bernasconi et al. (2011) published work from a multidisciplinary study of a Damma glacier in Switzerland, which examined functional linkages between weathering, soil texture, chemical properties, biotic activity, microbial diversity, and overall mechanism in the landscape. The results of this work can draw conclusions to explain soil development across glacial moraines under the similar condition of other sub-arctic landscapes in Iceland.

1.10 References

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Chapter 2. SOIL CHEMICAL PROPERTIES DYNAMICS IN GLACIAL MORAINES ACROSS A CHRONOSEQUENCE: BREIÐAMERKURJÖKULL, ICELAND

2.1 Abstract

The glacier foreland is the area of newly-formed landscape in front of a glacier. As the glaciers of Iceland continue to retreat new soil surface is exposed to plant and soil succession.

The glacial fore-field of the Breiðamerkurjökull serves as a chronosequence to study the morphological, physical, and chemical changes of the soils. On the moraines, evidence of the influence of seabirds was observed by the formation of hummocks, which were sampled for each age-group. The presence of seabirds is expected to enrich the soil nutrients and enhance the overall soil development. Soil samples were also collected from nearby birch (Betula pubescens) woodlands, representing soils in a potentially future mature soil profile. This analysis focuses on the chemical and nutrient gradients formed along the chronosequence in the glacial moraines, and compared to point-centered influence of seabirds. The soil pH (H2O) ranged from 8.2 to 5.7 in a

127-year old moraine, however remained consistent in the hummocks averaging at 5.8 pH after only 35 years. The SOC and TN generally increased over the moraines chronosequence, both with maximum concentration in the 87-year old moraine, with 1.36% SOC and 0.07% N. The hummocks showed significantly higher values for both SOC and TN with peak concentrations in the 127-year old hummocks at 14.5% SOC and 1.15% N, indicating the presence of seabirds provides enrichment for the soil. The C: N ratio was large in the initial moraines, but narrowed over the chronosequence, averaging at 30:1. The C: N ratio was significantly less in the hummocks averaging at 14:1 for both depths sampled. Analysis of available macro- and micro-

39 nutrients showed various trends of increasing concentrations, decreasing concentration, or no significant trend in the chronosequence. The available Fe decreased with time from 535 μg Fe g-1 in the initial 5 years to 373 μg Fe g-1 in the 127-year old moraine, and the Al concentration increased availability from initial 661 μg Al g-1 to 1026 μg Al g-1 in the 87-year old moraine. The volcanic soils of the region, exhibit distinctive soil properties including, low bulk density, variable charge characteristics, and high phosphate immobilization. The P-retention of the moraines increased over time reaching 26.6% P-retained in the 127-year old moraine, 48.9% P in the 127-year old hummock, and 87.5% P in the woodland area. However, the moraine values showed significant differences for many soil properties, when compared to those for the hummocks. This study supports the hypothesis that point-centered input of seabirds into the soil landscape can locally enhance the chemical properties, nutrient availability and rates of soil formation. The Breiðamerkurjökull chronosequence demonstrates a unique case study of various chemical and nutrient properties of the glacial moraines and how they change over time. This study is also leading to conclusions that the bird hummocks and other stable sites (i.e. reference area) are places were soil builds by accumulation instead of traditional weathering processes.

2.2 Introduction

The study was conducted in Vatnajökull National Park, Iceland, over the glacial fore- field of the Breiðamerkurjökull glacier (64°0’N; 16°2’W) (Figure 2.1). This quantitative experiment uses chemical methods to study the effects of time as a soil-forming factor through a

122-year chronosequence in the glacial fore-land. Thus, observed differences between soils of different ages forming a sequence are deemed to be the result of the lapse of varying intervals of time since the initiation of soil formation (Stevens and Walker, 1970). The latter in this case study is the time which the land’s surface is exposed, post-glacial retreat and moraine deposition. This 40 is an estimation of relative age or degree of maturity of soils. The importance of the role of time in the formation of soils was recognized by Jenny (1941), discussing the approach to the study of time as a "soil-forming factor" is to recognize and investigate a chronosequence. Defined as a sequence of soils in which the dominant variable accounting for any physical, chemical and biological differences has been the duration in time over which the sequence has developed

(Birkeland, 1999). Jenny's theories have been discussed by Crocker and Major (1955), Huggett

(1998) and utilized in many studies over deglaciated terrains (Matthews, 1992).

The chronosequence quantifies the trends of each variable analyzed in the soil over time.

This approach can be highly appropriate for addressing questions about soil development, when the soil forming factors are held constant, except for time (Walker et al., 2010). The

Breiðamerkurjökull study is focused on two main research questions: 1.) How are nutrient and chemical properties developing in glacial moraine soils, with increasing age of moraine and exposure to soil forming factors? and 2.) Will the nutrient and chemical trends measured in the glacial moraine soils be similar to the concentrations measured in the bird hummocks? Based on the evidence of seabirds influence on soil properties (Otero et al., 2018; Zwolicki et al., 2013) the point-centered presence of seabirds is expected to enrich the soil nutrients and enhance the overall soil development. The results of these investigations assist with conclusions to explain soil development across glacial moraines under similar conditions of the Icelandic landscape.

2.3 Materials and Methods

2.3.1 Study Site

This experiment was conducted over a glacial fore-land adjacent to Breiðamerkurjökull glacier, an outlet glacier from the Vatnajökull ice cap. The ice cap is situated in a maritime climate with low summer temperatures (maximum average temperature of 11◦ C in the warmest months) and high winter precipitation (maximum annual precipitation more than 4000 mm). The 41

Vatnajökull ice cap is the largest (≈ 8300 km2) ice cap of Europe situated in the south eastern part of Iceland, and all the glaciers of the ice cap are of the temperate type (Reijmer et al., 1998).

Breiðamerkurjökull ranks as the fourth largest outlet glacier of Vatnajökull ice cap, SE-Iceland

(Guðmundsson, 2014).

The landscape is covered in a series of moraines deposited from the glacier, as well as many braided streams and water flowing towards the Jökulsárlón Lake. The moraine material is a mixture of ground volcanic rocks, gravel (15 – 60%), glassy tephra and unsorted eluvium materials. This covers the outlet glaciers a significant extent, due to relatively frequent events of tephra fall from active volcanoes. The vegetation dominated by the region includes varying lichens, mosses, grasses, sedges, crowberry and billberry shrubs (e.g. Empetrum nigrum and Vaccinium myrtillus), and tortuous forms of willow and birch shrubs (e.g. Salix phylicifolia, Salix lanata, and Betula pubescens). The wildlife in the area includes a variety of seabird species, potentially grazing sheep (it is unknown how many sheep could be potentially grazing in the region), foxes and various microorganisms (Table 2.1). The sparsely vegetated moraines have attracted seabirds, as the primary wildlife, by utilizing the area for roosting and nesting purposes. Many hummocks were either located in the open area or on higher ridges, without vegetation this is ideal for a bird to view the area for potential predators.

Figure 2.1 Map of Vatnajökull National Park and its outlet glaciers, including Breiðamerkurjökull glacier in the south-east. (Google Earth open source satellite images, 2018).

Table 2.1 Bird species information of common seabirds taken from INH (2017). Common Name Species Name Common Name Species Name Arctic Turn Sterna paradisaea Artic Skua Stercorarius parasiticus

Puffin Fratercula artica Herring Gull Larus argentatus

Black Guillemot Cepphus grylle Common Gull Larus canus

Common Guillemot Uria aalge Oyster Catcher Haematopus ostralegus

Gannet Morus bassanus Turnstone Arenaria interpres

Great Skua Stercorarius skua Dunlin Calidris alphina

This study area is confined between the ice of the glacier, and the associated landscapes left by the two medial moraines Máfabyggðarönd to the west and Esjufjallarönd and Jökulsárlón glacial lake to the east (Vilmundardóttir et al., 2015). The southern area of the

Breiðamerkursandur glacio-fluvial plains is closely located near the Atlantic Ocean. Despite being isolated by glaciers and glacial rivers, the area has been utilized by farmers for sheep grazing, as well as, limited tourism within the southern and eastern shores of Jökulsárlón. The climate is maritime with cool summers and mild winters (Einarsson, 1984), with a mean annual temperature of ~5 °C. The glacier front has receded since 1890, although with static or readvancing periods, exposing various kinds of geomorphic features; e.g. thick ground moraines and a series of end moraines. Breiðamerkurjökull retreat pace slowed down in the 1960s and has accelerated after the 1990s to the present (Guðmundsson et al., 2017), since the LIA the glacier terminus has retreated by approzimately 4–6 km on land and ~7 km where the glacier calves into

Jökulsárlón lagoon.

The moraines are composed of unsorted material derived from rock formations in the vicinity, which feature mostly volcanic basalt and hyaloclastite (Jóhannesson and Sæmundsson,

2009), consisting of bedrock from the Late Pliocene, Lower Pleistocene, and Holocene lava flows

(younger than 11,000 years). Tephra, fragmental materials produced in volcanic eruptions, is a substantial constituent of the moraines originating from sub-glacial volcanoes, such as Katla,

Grímsvötn, Bárðarbunga, and Öræfajökull central volcanoes (Óladóttir et al., 2011).

2.3.2 Experimental Design

Using a chronosequence, this study was designed to analyze soil development rates along the recessional path of Breiðamerkurjökull glacier. The study area is a relatively flat landscape, with one small drop in relief where the glacier terminus was located in ~1960 and from there the land rises gradually to the present day terminus (Vilmundardóttir et al., 2015). There are some streams that can change in flux throughout the year depending on volume of glacial melt. The set- up for the sample collection spans across a series of moraines that have been exposed and deposited as a result of the glacial recession. Samples were collected during the summer of 2012, where sampling sites were restricted to end or ground moraines with a known/estimated time of deposition: 2012, 2004, 1994, 1982, 1960, 1945, 1930 and 1890, comprising 8 age groups (Figure

2.2). The outline of the moraines was identified with a GPS; five points were randomly selected for each of the moraines for soil sampling. These sites were considered well drained and without any signs of disturbance, as well as on the northern side of moraine ridges, and avoided sites of considerable sediment deposition. Hummocks sampled in 2017 were not taken from the most recent moraines, 2004 and 2012, due to the lack of evidence of seabird formation of hummocks.

This site has observed formation of patches across the landscape with increased vegetation and species richness (Vilmundardóttir et al., 2015); these have been identified as bird hummocks. Hummocks are created by the accumulation of droppings where birds regularly perch and defecate. The Breiðamerkursandur is one of Iceland's largest nesting grounds for the Great Skua (Stercorarius skua) (Lund-Hansen and Lange, 1991). The

Great Skua and Arctic Skua have had considerable impact on the soil environment and created the bird hummocks on the moraines as a result. These topographically are located primarily on the summits of the moraines. This experimental design is aiming to compare the moraine soil samples to the bird hummocks samples at each age group. This allows an investigation of the impact of seabirds on the soil environment. Sampling of the hummocks was expanded in the summer of 2017; each age group was sampled at three different randomly selected hummocks.

As a control for comparing the results of analysis, a climax ecosystem was located

~11 km to the west (Figure 2.2). The birch and willows are the species that characterize a climax ecosystem in Iceland and in theory, those species would represent the final stages of development on the Breiðamerkurjökull moraines. In order to compare the young moraine soils with those of a mature ecosystem, soil samples were collected within the birch woodlands at Stórihnaus at Kvísker. Tephrochronology is based on the identification, correlation, and dating of layers of volcanic ash or tephra layers in the soil profile (Thorarinsson, 1944). Tephra layers are also important for absolute dating, and analyzing the pedogensis between different sites, such as the moraines and hummocks.

Figure 2.2 Study area at Breiðamerkurjökull. The lines demonstrate the glaciers position at different years including: 1890, 1930, 1945, 1960, 1982, 1994, 2004 and 2012, which were redrawn from S. Guðmundsson (2014) and O. K. Vilmundardóttir via personal communication and collaboration. The black points mark soil sampling sites collected in 2012, and green stars mark sampling sites of the bird hummocks collected in 2017. Samples were also collected in the birch woodlands at Stórihnaus 11 km southwest of the study site as a control, reference area. G, B, K and Ӧ mark the location of Grímsvötn, Bárðarbunga, Katla and Ӧræfajökull subglacial volcanoes.

2.3.3 Field Measurements and Soil Sampling

Soil samples were collected in June 2012 (Vilmundardóttir et al., 2015), and May 2017, from the Breiðamerkurjökull glacial fore-field. There are a series of moraines, as a result of different times of the frontal deposition from the glacier. The chronosequence follows the different moraines in the fore-field, which includes 8 age groups (2012, 2004, 1994, 1982, 1960,

1945, 1930 and 1890), 5 moraine samples were collected at each to a depth of 0 – 5 cm. The moraine sites are so high in gravel content, there is very little soil development and can only be sampled to the shallow depth. The hummocks were present at the age groups from 1994 – 1890; these were sampled at two depths (0 – 5 cm, 5 – 15 cm). The hummocks are visibly more developed in the soil profile, and can be sampled deeper than the moraines. Soils were also sampled in a birch forest close to the Kvísker farm, north of Stórihnaus; three soil profiles were sampled (0 – 5 cm, 5 – 15 cm, 15 – 30 cm) and described down to 30 cm depth. All sampling was performed within a 0.25 m2 quadrant (Figure 2.3); general information on the site was recorded including: identifying vegetation species, description of relief, noting of any feces present, and describing the soil profile. Bulk soil samples were taken at each depth and bagged to return for further chemical analysis. Each sampling point was also photographed at each stage of the procedure as a visual record of the vegetation, size, relief, soil profile, and noted observations.

Figure 2.3 Images of procedure for sampling at an 1890 bird hummock. Left-top: The group is observing, discussing and taking notes over the sampling site under its current conditions, as well as, documenting site on the GPS. Right-top: Example of the quadrant photographed at each site sampled. Bottom: A profile of hummock up to 15 cm, which was the maximum soil depth, at the base of this profile there are large stones and gravel (bottom-left) (Turner, 2017).

2.3.4 Sample Analyses

2.3.4.1 Sample Preparation

Soil samples were returned to the University of Iceland for further chemical analysis.

Samples were air dried and sieved at 2mm. For SOC and total N analysis, subsamples were ball- milled and sieved at 150 μm.

2.3.4.2 Phosphate-Retention (P-Retention)

P-Retention was measured using an extraction method described in Blakemore et al. (1987). The non-bioavailable P is extracted using a P-retention solution and Nitric Vanadomolybate Acid

Reagent (NVAR), and analyzed using a spectrophotometer (Blakemore et al., 1987). The reagent reacts rapidly with the phosphate ions yielding a blue color as representation of the concentration

(Murphy and Riley, 1962). Initially before each set of soil samples was run, a set of working standards absorbance were read and recorded, at 466 nm, setting the instrument to zero on DI water (Blakemore et. al., 1987). These values are used to prepare a standard curve of P- retention against the absorbance reading (Table 2.2), and the linear regression from this is used to calculate the appropriate concentrations of the samples. The absorbance readings from the soil samples were recorded and are inserted into the calibration equation. The response variable is the percentage of phosphorus ions retained in the soil, and each sample was tested in duplicates.

Table 2.2 Preparation of working stocks for P-retention solution using 50-ml or 25-ml volumetric flasks. Final % P-retention DI Water P-retention DI Water Concentration Retention solution 50 ml- solution 25-ml 50-ml flask flask 25-ml flask flask 0 mg P / ml 100% 0 50 0 25 0.2 mg P/ ml 80% 10 40 5 20 0.4 mg P/ml 60% 20 30 10 15 0.6 mg P/ ml 40% 30 20 15 10 0.8 mg P/ ml 20% 40 10 20 5 1.0 mg P/ ml 0% 50 0 25 0 * Working stocks were made new for each calibration used on a batch of samples.

2.3.4.3 Soil pH (H2O)

The soil pH in the H2O procedure requires weighing 10 g of 2 mm sieved air-dried soil, into a 50- or 100-ml beaker and adding 25 ml of DI H2O (1:5). Electrodes may be placed in the clear supernatant above the soil, directly in the settled soil, or the entire suspension may be stirred during the pH determination (Thomas, 1996). The soil pH (H2O) was determined after stirring the suspension for 2 hours. Each sample was conducted in the same method of suspension, and between pH readings the electrode was rinsed with DI water.

2.3.4.4 Soil pH (NaF)

Andic properties were also indirectly determined using the pH in NaF (Fieldes and

Perrott (1966). This is used as an indication of the presence of active aluminum, and is also known a ‘Fluoride field test’. When high pHNaF values are found, this can indicate soils derived from volcanic materials and ash. The procedure begins with 1 g of air-dried, <2 mm sieved soil weighed in a 100-ml beaker, then add 50-ml NaF reagent and stir vigorously for 1 min. Exactly at

2 minutes after adding the reagent, the pH is read from the electrode after ensuring the suspension

51 is well stirred. The 2 minute mark is important to keep consistent in order for most accurate readings across the samples.

2.3.4.5 N-Species

The determination of N-species in soil extraction is described by Shand et al. (2007).

Colorimetric measurements were made using a spectrophotometer, using absorbance measurements were made using a cuvette, instead of the microplate used in Shand et al. (2007).

There are multiple components of N that are determined in the method including: Ammonium

+ - - (NH4 ), Nitrate (NO3 ), and Nitrite (NO2 ). The determination of the N-species requires soil samples air-dried and <2 mm, and 2 M KCl; 3 g of soil is mixed with 30-ml of 2 M KCl in a centrifuge tube. The group of samples are shaken for an hour at 160 r.p.m. then centrifuged for 15 minutes. The extracted solution separated from the soil sample is run through a filter system, and stored in a sterile centrifuge tube in a refrigerator until used for analysis.

+ Ammonium Concentration (NH4 )

+ + The analysis for NH4 requires two reagents (A & B), and working standards for NH4

(Crooke and Simpson, 1971). Reagent A and B were described in Shand et al. (2007). Standard

Solution is used in this method to create a calibration curve for the different concentrations of

+ NH4-N, laid out in Table 2.3. The Stock Solution I should be at 100 mg NH4 /L, equal to 77.60

NH4-N. The standards used for the calibration curve begin with the solution II, 3.10 mg NH4-N/L and diluted from there. The samples were ran in small groups of 8-15 samples at a time, and placed in an incubator at 25 ºC for 25 minutes (Koroleff, 1976; Crooke and Simpson, 1971).

After the samples have rested, the absorbance is measured in the spectrophotometer at 630 nm.

The absorbance values (Y-values) is plotted against the concentration of the standards (X-values); adding a linear regression to the chart, and show the equation for linear regression and R2 value.

The equation is used to plot the sample absorbance values to extract the concentration of mg

- NH4-N L.

Table 2.3 NH4-N working standards used in calibration curve for determining ammonium.

Goal mg NH4-N/L Solution II ml DI water ml Final mg NH4-N/L 0 0 ml 10 ml 0 0.14 0.5 ml 9.5 ml 0.155 0.60 2.0 ml 8.0 ml 0.62 1.00 3.2 ml 6.8 ml 0.992 1.20 4.0 ml 6.0 ml 1.24 1.40 4.5 ml 5.5 ml 1.395 3.10 10 ml 0 ml 3.10

- - Nitrate (NO3 ) and Nitrite (NO2 ) Concentrations

- - The determination for NO3 and NO2 requires multiple solutions including: Catalyst

Solution, Sodium Hydroxide (NaOH), Hydrozine Sulfate, Sulphanilamide and NEDD

(Shand et al., 2007). These various solutions were made using the Shand et al. (2007) approach for determination of nitrate and nitrite.

- - - - The analysis needs working standards for NO3 at 50.0 g KNO3 L , and NO2 49.94 g

- - KNO2 L, displayed by Table 2.4. These main stocks are both diluted to an intermediate

- working stock concentrated at 1 mg L for both NO3-N and NO2-N as described by (Table

2.4).

Table 2.4 Concentrations used of the NO3-N and NO2-N stocks for working standards used in developing calibration curves.

Concentration mg /L Stock 1 mg NO3-N/L Stock 1 mg NO2-/L DiH2O 0 0 ml 0 ml 10 ml 0.05 0.5 ml 0.5 ml 9.5 ml 0.10 1 ml 1 ml 9 ml 0.20 2 ml 2 ml 8 ml 0.5 5 ml 5 ml 5 ml 1.0 10 ml 10 ml 0 ml

Once all the reagents and stocks are prepped, the samples can be analyzed from the extractant filtered off the soil samples. The procedure for the final solution that is colorimetrically evaluated for NO3-N and NO2-N concentrations is described by the Shand et al. (2007) method.

The absorbance of the solution was measured at 540 nm wavelength. Absorbance values were recorded for each sample, from the moraines, hummocks and woodlands. Standard calibrations were ran with each batch to determine the LOD and accuracy of the readings.

NH4-N NO3-N NO2-N

0.6 ml •NEDD •Reagent •NEDD 0.6 ml 0.833 ml B 2.25 •Sulphanilamide ml •Hydrozine •Sulphanilamide 0.6 ml Sulfide 2.25 ml •Reagent A 0.833 ml •NaOH 0.6 ml •DiH O 1.35 ml 2 •Catalyst 0.6 ml Solution •Sample 8.33 ml •Sample 5.8 ml •Sample 5.8 ml

Figure 2.4 Model of three different N components have different combination of reagents and solutions (Shand et al., 2007). The furthest left breaks down the combination for NH4-N determination. The center breaks down the solutions for the NO3-N, and the right is the composition for NO2-N.

2.3.4.6 Total C, Total N, and C: N Ratio

Total C analysis of soil includes converting the various forms of C in soils to carbon

dioxide (CO2) by either wet or dry combustion and subsequent quantitation of evolved CO2 by

gravimetric, titrimetric, volumetric, spectrophotometric, or gas chromatographic techniques. The

dry combustion method was used for the moraines, hummocks and woodlands soil samples. This

is conducted by heating the sample (~900 ºC) using C-N analyzer (Fisher 2000). The mean error

(ME) of –1.08 g kg -1 indicated a systematic under prediction of the SOC by the Heanes (1984)

55 adaptation of Walkley-Black (1934) method, in comparison with the dry combustion method

(Nelson and Sommers, 1996; Konare et. al., 2010).

Air-dried samples were ball-milled to 150 μm, which allows for reproducible results in determinations of C with a homogeneous sample (Nelson and Sommers, 1996). The sample is further processed by dry combustion in the C-N analyzer; the results include the total carbon as well as the total nitrogen. The results of the analysis present the total C, however, soils may contain both organic and inorganic C thus total C analysis procedures recover both forms. These soils are not calcareous so the total C is assumed to be SOC (Heanes, 1984). Using the SOC and total N, the C: N ratio can be calculated and used as a measurement to understand the trends in the C and N in the samples organic material.

2.3.4.7 Mehlich III available nutrients

Soil samples were submitted to the Service Testing and Research Laboratory (STAR

Lab), a chemical analysis laboratory located in Wooster, Ohio (campus of the Ohio State

University). The samples were air-dried, <2 mm sieved soil, and submitted in paper coin envelopes.

The Mehlich III is an extractant, which extracts the various elements from the soil solution (Mehlich, 1984). This procedure provides simple, yet accurate determination of various macro- and micro-nutrients. The method proceeds with two grams of soil sample (< 2 mm) was weighed out and mixed with 20 mL Mehlich III solution (Mehlich, 1984). Extracted P, K, and micronutrients were analyzed by Inductively Coupled Plasma-Atomic Emission Spectrometry

(ICP). The ICP also known as Inductively Coupled Plasma, a type of atomic emission spectroscopy, which is capable of detecting metals and several non-metals at very low concentrations. The solid soil samples are digested using a Mars closed-vessel microwave, then

56 processed through the ICP to solve for concentrations of the soil nutrients (Al, B, Ca, Cu, Fe, K,

Mg, Mn, Mo, Na, P, S, and Zn).

2.3.5 Data Analysis and Justification

These results were analyzed with 1-way Analysis of Variance (ANOVA) to test if there was a difference among the depth and age groups across the chronosequence, as well as between the moraine and hummock samples. Significant differences between specific depth and age groups were then determined using Tukey’s Pairwise Significant Difference test at α = 0.05.

These statistically analyses were determined using Minitab 18, as well as, graphs and linear regression plots.

2.4 Results of Analysis

2.4.1 Trends across the chronosequence

Data for each moraine age-group and depth were compared across the chronosequence and analyzed by 1-way ANOVA. The results of ANOVA soil properties were significant between the groups for all properties, except in the nutrients Ca, Cu, Mg, Mo, and S concentrations (Table

2.5). Thus there is small enough p-value for all other properties to have significantly different means in the age-groups of the chronosequence. The moraines, hummocks and woodlands have demonstrated a difference between treatment groups means for all soil properties, except the nutrients Ca, Cu, Mg, Mo, and S (Table 2.5).

The ANOVA analysis compared the measurements means across the chronosequence at the different age-groups, with the different group combined and depths (Table 2.5). The ANOVA comparisons between years showed that there is evidence for differences between means of age- groups for all soil properties measured, except total C, total N, nutrients K, Mg, Mo and P. The data result comparing the age-groups of the chronosequence of moraines in the top 5 cm,

57 including reference to the birch woodlands is presented in Table 2.5. All ANOVA analysis showed strong evidence for different means between groups for all soil properties, except the nutrients B and Mo which have large p-values (Table 2.5). The B and Mo have evidence to support than the means of all groups are equal. This supports that many soil properties have differences across the chronosequence in the moraine samples at different age-groups.

One-way ANOVA tests were conducted over the hummocks at both depths measured 0 –

5 cm and 5 – 15 cm (Table 2.5). The results compared the age-groups of the chronosequence of the hummocks including reference to the birch woodlands. Results determined the differences between some of the means to be statistically significant for some soil properties including, P- retention, NH4-N, and nutrients Al, Fe, and Mn (Table 2.5). These characteristics show significant differences at different ages of the chronosequence. All other soil properties resulted in p-values greater than the level of significant (α = 0.05), thus the differences between the age- group means are not statistically significant (Table 2.5).

The data values of Table 2.5 compare the age-groups of the chronosequence of hummocks sampled at 5 – 15 cm. The results compared the 7 different age-groups of the chronosequence of the hummocks including reference to the woodlands. The p-value less than the level of significant shows strong evidence that there is a difference between some of the means.

The difference of the means is statistically significant in soil properties including, pH (NaF), P- retention, NH4-N, and nutrients Al, Fe, K, and Mn (Table 2.5). The differences between the means are not statistically significant in all other properties analyzed with ANOVA including, pH

(H2O), total C, total N, CEC, and nutrients B, Ca, Cu, Mg, Na, P, and S (Table 2.5).

Table 2.5 ANOVA data table of p-values for each one-way ANOVA analysis over moraines, hummocks and woodlands.

NH4-N Nutrient μg g-1 soil pH pH P-retention Total C Total N mg kg-1 (H2O) (NaF) (%) (%) (%) soil Ca K Mg P p-value1 < 0.0001 < 0.0001 < 0.0001 < 0.0001 < 0.0001 < 0.0001 0.022 < 0.0001 0.008 < 0.0001 p-value2 <0.0001 < 0.0001 <0.0001 0.016 0.069 < 0.0001 0.439 0.001 0.184 0.259 p-value3 < 0.0001 < 0.0001 < 0.0001 < 0.0001 < 0.0001 < 0.0001 < 0.0001 < 0.0001 < 0.0001 < 0.0001 p-value4 0.653 0.009 <0.0001 0.121 0.168 <0.0001 0.332 0.147 0.019 0.014 p-value5 0.841 <0.0001 <0.0001 0.006 0.054 <0.0001 0.248 <0.0001 0.403 0.375 -1 Nutrient μg g soil Al B* Cu Fe Mn Mo** Na S Zn*** p-value1 < 0.0001 < 0.0001 0.368 < 0.0001 <0.0001 0.433 < 0.0001 0.558 <0.0001 p-value2 < 0.0001 0.005 < 0.0001 < 0.0001 < 0.0001 0.736 < 0.0001 < 0.0001 < 0.0001 p-value3 < 0.0001 0.057 < 0.0001 < 0.0001 < 0.0001 0.343 < 0.0001 < 0.0001 < 0.0001 p-value4 <0.0001 0.002 0.008 <0.0001 <0.0001 0.822 0.023 0.152 0.38 p-value5 <0.0001 0.004 0.011 <0.0001 <0.0001 - 0.025 0.046 -

1ANOVA Testing the means of the groups (i.e. Moraines, Hummocks, Woodland) with combined depths of each soil age (α = 0.05). 2ANOVA Testing the means of the age-groups of chronosequence with the groups and depths combined in means (α = 0.05). 3ANOVA Testing the means of the age-groups of the moraines at 0 – 5 cm across the chronosequence, including woodland reference (α = 0.05). 4ANOVA Testing the means of the age-groups of the hummocks at 0 – 5 cm across the chronosequence, including woodland reference (α = 0.05). 5ANOVA Testing the means of the age-groups of the hummocks at 5 – 15 cm across the chronosequence, including woodland reference (α = 0.05).

-1 NO3-N and NO2-N mg kg soil* did not have enough data to run ANOVA analysis B* Results did not include 15 observations below the LOD in ANOVA analysis Mo** Results did not include 56 observations below the LOD in ANOVA analysis Zn*** Results did not include 23 observations below the LOD in ANOVA analysis 59

2.4.2 Soil pH (H2O)

The soil pH (H2O) p-value provides evidence of different means across the three groups

(e.g. moraines, hummocks, control-woodlands), and across each year of the chronosequence when all three treatment group means are combined (Table 2.5). The means of soil pH (H2O) for hummocks top 5 cm are not statistically significant between age-groups of the chronosequence

(Table 2.5). The pH remains above neutral (~7.0) as the soil system is rejuvenated with ions released by weathering without the influence of organic acids that would lower the pH. The moraines show a trend that they tend to be alkaline in the youngest moraine (2012) at 8.21 pH, which steadily appears to be declining over time (Table 2.6). The average pH (H2O) in the moraines are close to neutral in 2004 and 1994. Figure 2.10 shows how the moraine soils are above neutral in the earliest age-group, and then declines to below neutral in 1982. The age- groups of moraines become more acidic over time, especially in the oldest moraines, which are very similar to the average pH of the woodland sample at 5.75, for 0-5 cm depth.

When these soils are covered with vegetation, the pH drops very rapidly, most likely due to the increased organic acids from plant roots and microorganisms establishing the community.

Alaskan volcanic ash soils measured pH (with 1:1 H2O) in 4 pedons, estimated 6.7, 5.8, 5.5 and

5.7 (Michaelson et al., 1987), which is a similar value to the woodland soil, as well as the older age-groups for the moraines and hummocks. When the system has depleted the easily weathered volcanic material inputs, the soil pH will eventually become low (Arnalds, 2008a).

Figure 2.5 Bar graph of the means and quartiles for each treatment group in the chronosequence.

Table 2.6 Data table of means, standard deviation and Tukey grouping from one-way ANOVA testing the effect of treatment at each age-group.

pH (H20) Moraines Hummock (0 – 5 cm) Hummocks (5 – 15 cm) Year Mean StDev Tukey* Mean StDev Tukey Mean StDev Tukey 2012 (5) 8.2 0.19 a ------2004 (13) 7.1 0.21 b ------1994 (23) 7.0 0.17 b 5.9 0.36 a 6.2 0.19 a 1982 (35) 6.5 0.19 c 5.9 0.33 a 6.1 0.17 a 1960 (57) 6.2 0.10 cd 5.9 0.29 a 6.1 0.17 a 1945 (72) 5.8 0.26 de 5.8 0.31 a 6.1 0.26 a 1930 (87) 5.7 0.23 e 5.8 0.19 a 5.9 0.28 a 1890 (127) 5.7 0.15 e 5.7 0.42 a 6.0 0.46 a Birch (Ref.) 5.7 0.10 de 5.9 0.19 a 6.1 0.03 a

*Letters indicate t-groupings that are significantly different in Tukey’s Pairwise comparisons

The hummocks did not show the same trend for pH (H2O) over the glacial moraine chronosequence. The hummocks are not significantly different at any age-group, instead the mean for all the hummocks at both depths (0 – 5 cm, 0 – 15 cm) stay within a range of values between

5.7 – 5.9 pH (H2O). This comparison of pH (H2O) is showing that the seabird’s inputs are changing the trend of pH (H2O) development overtime. The Tukey Pairwise comparison of the groups showed that all age-groups shared the same letter and similar means, including the reference woodlands pH (Table 2.6).

The results of analysis support the previous findings of Vilmundardóttir et al. (2015) showing the moraines pH (H2O) decreased with time, and the hummock were generally lower ranging between 5.2 and 6.2. There is evidence to support the hypothesis, that seabirds have a significant influence on the trend of soil acidity.

2.4.3 Soil pH (NaF)

There are several chemical tests associated with minerals of the clay fraction in volcanic soils, including the reactivity of sodium fluoride (NaF), P-retention and content of Al, Fe and Se extracted with ammonium oxalate (Valle et al., 2014). Determining pHNaF is based on the release of OH- ions into the soil solution by the exchange of OH- for F-, which increases the pH and forms flualuminate. Soil pHNaF values can be lowered by acids derived from non-humified organic matter or increased when the NaF solution reacts with soil noncrystalline minerals and/or carbonates (Perrott et al., 1976). Furthermore, it can also be increased due to NaF reactions with exchangeable Al, Al-humus complexes, and interlayered hydroxyl-Al present in layer silicates

(Wada, 1985). This property was determined by the indirect method of determining soil pH in 1

M NaF solution, by mixing 0.5 g soil with 25 ml NaF.

The pHNaF values of the moraines ranged from 8.1 to 9.6 in the soil, 8.5 to 9.1 in the hummocks (0 – 5 cm), with the top depth of the woodland measured at 10.2 (Table 2.7). The hummocks (5 – 15 cm) measured pHNaF ranging from 9.1 to 10.0, with the lower depth of the woodland at 11.0 (Table 2.7). Overall there is some changes between age-groups in the glacial chronosequence, therefore the different groups are examined separately.

The lowest pHNaF values range in the youngest moraines, from 2012 to 1994, which share a significant mean values ranging from 8.0 to 8.3 (Table 2.7). Then the moraines shows a trend of increasing pHNaF values with increasing chronosequence age (Figure 2.6). The 1960 moraine average is greater than the pHNaF measurements for the 1945 and 1930, but shares a significant grouping (Table 2.7). The measurement for 1890 and 1982 share similar values with 1890 being

8.98 pHNaF, and the woodland reference soil is 10.2 (Table 2.7). The Skaftafellsjökull moraines showed a similar trend of measurements (Vilmundardóttir et al., 2014) ranging from 8.0 to 9.2 in the 0 – 10 cm, and 8.3 to 9.5 pH (NaF) in the 10 – 20 cm depth. 63

Table 2.7 Data table of means, standard deviations and Tukey pairwise comparison group letters pertaining to soil pHNaF.

pH (NaF) Moraines 0 – 5 cm Hummocks 0-5 cm Hummocks 5-15 cm

Chronosequence Mean StDev Tukey* Mean StDev Tukey Mean StDev Tukey Age (Year)

2012 (5) 8.1 0.17 e ------2004 (13) 8.3 0.27 e ------1994 (23) 8.3 0.35 de 8.8 0.18 b 9.1 0.37 c 1982 (35) 8.7 0.62 cde 8.7 0.33 b 9.5 0.25 bc 1960 (57) 9.6 0.14 ab 8.7 0.43 b 9.8 0.04 b 1945 (72) 9.3 0.25 bc 8.9 0.17 b 10.0 0.02 b 1930 (87) 9.2 0.10 bc 9.1 0.04 ab 9.9 0.10 b 1890 (127) 9.0 0.43 bcd 8.5 1.03 b 9.9 0.36 b Birch (Ref.) 10.2 0.30 a 10.2 0.30 a 11.0 0.02 a

*Means that do not share a letter are significantly different (Tukey Group)

The hummocks at 0 – 5 cm measured pHNaF values ranging from 8.5 to 9.1, and for the 5

– 15 depth ranging 9.1 to 10.0 (Table 2.7). The means of the hummocks at 5 – 15 cm show the trend of increasing means with increasing chronosequence years (Figure 2.6). This general trend of increasing pHNaF is observed in all groups analyzed. Vilmundardóttir et al. (2015) is among the few studies to have been conducted considering the pHNaF of soils across a chronosequence, in order to evaluate how they develop over time. When high pHNaF values are found, this can be concluded as soils derived from volcanic materials and ash.

Figure 2.6 Bar graph of pHNaF means from age-groups measured across the chronosequence, with linear regression lines for relationship between time and pHNaF.

2.4.4 P-Retention

Walker and Syers (1976) put forth a model of soil P transformations, which suggests that primary mineral-P slowly dissolves and is either taken up by organisms or is sorbed onto secondary mineral surfaces (Tiessen and Stewart, 1985). A study done on a chronosequence of the Hawaiian archipelago concluded that long-term development largely coincides with the conceptual model, but how P is distributed in different fractions provides a useful context for evaluating contemporary cycling of P (Crews et al., 1995). The abundance of active Al and Fe compounds can be estimated by measuring phosphate sorption or the pH ride due to fluoride

65 sorption (pHNaF) (Shoji et al., 1993). Nonallophanic Andosols show a larger P-retention than allophanic Andosols, determined using Blakemore’s method (Blakemore et al., 1987).

The moraines measured lower percentages of P-retained in their soil samples than the hummocks, Figure 2.7 shows the 0 – 5 cm moraine as the lowest series of points. There is not a significant difference between the youngest moraines between 2012, 2004, and 1994 (Table 2.8), with means ranging from 12.1 – 12.5%. The 1982 moraine has a different grouping, and the lowest P-retention at 11.97%. The remaining moraines increase their P-retention capacity from

1945 to 1890. The oldest moraine, 1890, measured 26.1% P, which is significantly less than the woodland soil at 87.5% in the top 0 – 5 cm (Table 2.8).

Table 2.8 Data table of moraines and hummocks percent P-retention measurements using Blakemore et al. (1987) extraction at different age-groups and both depths for hummocks.

P-retention Moraines (0-5 cm) Hummocks (0-5 cm) Hummocks (5-15 cm) (%) (Years) Mean StDev Tukey Mean StDev Tukey Mean StDev Tukey 2012 (5) 12.5 2.1 cd ------2004 (13) 12.1 3.1 cd ------1994 (23) 12.1 2.9 cd 14.5 3.2 d 14.3 1.9 d 1982 (35) 11.9 3.3 d 25.4 2.9 cd 17.7 1.5 d 1960 (57) 18.2 3.7 bcd 26.8 3.8 cd 18.7 1.0 d 1945 (72) 21.7 5.3 bcd 32.8 1.6 bcd 24.8 2.6 cd 1930 (87) 22.4 3.5 bc 38.0 11.2 bc 33.1 3.7 bc 1890 (127) 26.1 10.1 b 48.9 13.7 b 40.0 2.9 b Birch (Ref) 87.5 3.8 a 87.5 3.8 a 90.7 8.1 a *Means that do not share a letter are significantly different (Tukey Group)

Consistently the averages for the top depth in the hummocks measured have a greater percentage of P-retained than the lower depth (Table 2.6). The youngest hummock, 1994, at the top depth 0 -5 cm measured 14.45%, which is ~2% more than the 1994 moraine. The 1982 and

1960 hummocks from 0 -5 cm showed similar values, according to the Tukey Pairwise comparison, at 25.3-26.8% P-retention. The percentage of P-retained increases quickly from 1945 to 1890, averages increasing from 32.8% to 38% to 48.9% P. This increase in P-retention of the hummocks shows to be changing more quickly over time than the moraines, as well as retaining higher percentages of P. The 5 -15 cm depth shows a similar trend as the 0 – 5 cm concentrations, however they are typically less than the top depth. The 5 – 15 cm depth of the 1994, 1982, 1960 hummocks measured at 14.3%, 17.7% and 18.7% P-retention in the soil (Table 2.8). The hummocks from 1945 to 1890 increased in retention from 24.8% to 33.1% to 40% P. The woodland 5 – 15 cm depth had a greater percentage of P-retained at 90.7% than the 0 – 5 cm depth at 87.5% P.

Figure 2.7 Bar graph of the percent P-retention using Blakemore et al. (1987) extraction in the moraines and hummocks measured. The plot shows the trends of group averages over time.

The Breiðamerkurjökull data shows that both groups are following a similar trend of increased P being retained and adsorbed to the soil as it develops. This tendency towards retaining P (25 – 80%) reflects the presence of allophane in these soils (Valle et al., 2014). P- retention is an empirical measure of the ability of the soil to rapidly remove P from solution, a process which renders the P unavailable to plants (Blakemore et al., 1987). The analysis of the seabird hummocks P-retention is not addressed in other investigations (e.g. Otero et al., 2018;

Beck et al., 1999; Borkowska et al., 2015) of bird hummocks, therefore assumptions must be drawn about the seabird’s inputs influencing the rate of development.

2.4.5 Nitrite (NO2-N), Nitrate (NO3-N), and Ammonium (NH4-N) availability

-1 + The limits of detection (LOD) of the colorimetric assays were 0.049 mg N kg for NH4 ,

-1 − -1 − 0.58 mg N kg for NO3 and 0.013 mg N kg for NO2 . The LOD was determined from calibration values. Brenner (2016) used the same approach to the N-species determination and

-1 also measured nitrate and nitrate concentrations below detection (LOD = 0.03 mg NO2-N kg soil

-1 and 0.69 mg NO3-N kg soil). The determination of N-species was tested on water extracts derived from samples from the moraines, bird hummocks and woodlands reference area. The

+ moraines measurements for NH4 across the chronosequence were originally hypothesized to be very low or unable to be detected, however there were measurable values at all sites in the moraines, hummocks and woodlands (Table 2.9).

+ 2.4.5.1 Ammonium (NH4 ) availability

-1 -1 Ammonium concentrations ranged from 0.53 mg NH4-N kg soil to 2.16 mg NH4-N kg soil for the moraines (0 – 5 cm) ranging from 2012 to 1890 (Table 2.9). The woodland reference

-1 -1 measured 38.64 mg NH4-N kg soil in the 0 – 5 cm depth, and 10.22 mg NH4-N kg soil in the lower depth, 5 – 15 cm (Table 2.9). The Tukey pairwise comparison of the age-groups show some similarities and significant different groupings across the chronosequence. Zwolicki et al.

-1 (2015) showed concentrations of 1.5 and 1.2 mg NH4-N kg soil in sites covered in mosses and lichens. There was similar means shared by most of the chronosequence including samples from

2012 to 1960, which all shared a Tukey pairwise significant comparison letter (Table 2.9).

However, these similar means show a slow trend of accumulating ammonium concentration with increasing chronosequence age at Breiðamerkurjökull.

-1 Table 2.9 Data table of average ammonium (mg NH4-N kg soil) concentration at different age- groups and by depth, with standard deviation in parentheses. Chronosequence Moraines 0 - 5 cm Hummocks 0-5 cm Hummocks 5-15 cm Age (Yr) 2012 (5) 0.58 (0.05) cd - - - - 2004 (13) 0.53 (0.04) d - - - - 1994 (23) 0.79 (0.21) cd 2.68 (3.58) c 0.17 (0.11) b 1982 (35) 1.14 (0.24) bcd 2.81 (1.88) c 0.21 (0.03) b 1960 (57) 0.64 (0.22) d 0.91 (0.46) c 0.18 (0.04) b 1945 (72) 1.77 (0.47) bc 9.44 (5.13) bc 1.64 (0.92) b 1930 (87) 2.16 (0.32) b 3.65 (1.17) c 2.26 (1.10) b 1890 (127) 2.00 (0.39) b 19.14 (6.66) b 4.58 (3.07) b Birch (~200) 38.64 (1.61) a 38.64 (1.61) a 10.22 (2.73) a *Means that do not share a letter are significantly different (Tukey Group)

The seabird’s hummocks 0 – 5 cm concentrations ranged from 0.91 to 19.14 mg NH4-N kg-1 soil, across the chronosequence from 1994 to 1890 (Table 2.9). In the hummocks lower depth

-1 (5 – 15 cm), concentrations of ammonium ranged from 0.17 to 4.58 mg NH4-N kg soil. Zwolicki et al. (2015) observed higher concentrations of ammonium in the soils of seabird colonies, values

-1 ranging from 7.9 to 58.0 mg NH4-N kg soil from 0 – 10 cm. The three youngest hummocks –

1994, 1982, and 1960 – at the 0 – 5 cm depth shared similar concentrations of ammonium. From

1960 to 1945 there is a significant increase in the concentration (Table 2.9) from 0.91 to 9.44 mg

-1 NH4-N kg soil. Which was followed by a decrease in concentration in 1930 to 3.65 mg NH4-N

-1 -1 kg soil, and another increase in concentration at the 1890 hummock to 19.14 mg NH4-N kg soil

(Table 2.9).

The hummocks lower depth also showed a trend of increasing concentration of ammonium with increasing age of chronosequence. The 1994 hummock (5 – 15 cm) measured the lowest concentration, and the values appear to increase slowly in each age-group until the

-1 1890 sites averaged at 4.58 mg NH4-N kg soil. The Tukey pairwise comparison showed that the hummocks (5 – 15 cm) from 1994 to 1890 shared a letter, thus they do not have significantly different values (Table 2.9); furthermore, there is difference between the woodland at 5 – 15 cm and the hummocks concentrations.

2.4.5.2 Nitrate (NO3-N) and Nitrite (NO2-N) Availability

Nitrite and nitrate concentrations were generally below the limit of detection, thus their precise concentrations are unknown and negligible (Table 2.10). However there were a few hummock samples at both depths that were above the LOD for both nitrate and nitrite. The means for these nitrate and nitrite concentrations derived from the groups that had 1 or 2 observations within detection range. The moraines measurements for nitrate and nitrite were below the LOD

(Table 2.10). The hummocks at 0 -5 cm had sites from the 1994 age-group that had detectable nitrate levels (Table 2.10), and at 5 – 15 cm had detectable measurements from both 1994 and

1982. There were detectable nitrite levels in the 1960 hummock (0 – 5 cm and 5 – 15 cm) and

1945 (5 – 15 cm) (Table 2.10).

It is difficult to interpret the trend in the chronosequence with so few samples with detectable amounts; a higher resolution cell is needed to get precise concentrations. Zwolicki et

+ - - al. (2015) measured available forms of N (NH , NO3 , and NO2 ) and found similar range of values to the Breiðamerkurjökull concentrations. When looking at the seabird colonies in

+ - Svalbard, Zwolicki et al. (2013) showed that the concentrations of NH4 and NO3 concentrations decrease as the soil is increased distance from the colony. The Breiðamerkurjökull study shows that the point-centered influence of seabirds in the foreland shows an overall increase in concentration than the surrounding moraines soils.

Overall, the amount of N in the soil is actually quite low and shared similar findings to

Vilmundardóttir et al. (2015), which found negligible amounts of N in the moraines from 2012 to

1994. The present Breiðamerkurjökull study refers to the newly exposed moraines, and compares the point-centered influence of seabirds. The soils with increasing vegetative cover, as seen in the hummocks (Vilmundardóttir et al., 2015), are most likely using the available ammonium as the

+ form of available N. The concentration of NH4 was higher in the hummocks than the moraines,

-1 specifically in the oldest moraine sample the moraine group showed 2.0 mg NH4-N kg , and the

-1 -1 hummocks observed 19.1 mg NH4-N kg in the top 5 cm and 4.6 mg NH4-N kg from 5 – 15 cm

(Table 2.9). Thus it can concluded that the seabirds are contributing to a higher pool of ammonium in the moraine soils. Otero et al. (2018) found that seabird excrements were ~80%

− uric acid, which rapidly mineralized to highly bioavailable forms of N, such as NH3 and NO3 .

Although the Breiðamerkurjökull soils did not determine high concentrations of nitrate or nitrite in either moraines or hummocks, these N-species could potentially rapidly be used or leached from the profile as soon as the ions are available in solution.

Table 2.10 Data table of average nitrate and nitrite concentrations available at different age- groups and by depth.

Chronosequence Nitrate (NO3-N Nitrite (NO2-N Group Age (Year) mg kg -1 soil) mg kg-1 soil)

2012 (5) < 0.58 <0.13 2004 (13) < 0.58 <0.13 1994 (23) < 0.58 <0.13 1982 (35) < 0.58 <0.13 Moraines 1960 (57) < 0.58 <0.13 0 -5 cm 1945 (72) < 0.58 <0.13 1930 (87) < 0.58 <0.13 1890 (127) < 0.58 <0.13 Birch (Ref.) < 0.58 <0.13 1994 (23) 0.871 (0.20) <0.13 1982 (35) <0.58 <0.13 1960 (57) <0.58 0.0431 (0.205) Hummocks 1945 (72) <0.58 <0.13 0 -5 cm 1930 (87) <0.58 <0.13 1890 (127) <0.58 <0.13 Birch (Ref.) <0.58 <0.13 1994 (23) 1.116 (0.38) <0.13 1982 (35) 0.866 (0.23) <0.13 1960 (57) <0.58 0.2321 (0.04) Hummocks 1945 (72) <0.58 0.1943 (0.06) 5 - 15 cm 1930 (87) <0.58 <0.13 1890 (127) <0.58 <0.13 Birch (Ref.) <0.58 <0.13

Standard deviation in parentheses. Nitrate LOD <0.581 mg kg-1 Nitrite LOD <0.1335 mg kg-1

2.4.6 Total N (%), Total SOC (%), and C: N Ratio

2.4.6.1 Total N

Most studies are consistent with the increasing N values through time, usually with a relatively rapid rise in early stages followed by a decline (Matthews, 1992). One the moraines of the Klutlan glacier showed relatively high concentrations of N (1.0 – 2.0%) in the first 15 years, but appear to decline slightly after 200 years (Jacobson and Birks, 1980). The total nitrogen (N

%) in the moraines (0 – 5 cm) ranged from 0.01% to 0.07% N across the 127-year- chronosequence (Table 2.11).

Figure 2.8 Bar graph of means from the groups, and standard deviation bars for TN.

The Tukey pairwise comparison shows similar group means for moraines between 2012 to 1945 moraines. The 2012, 2004, and 1994 moraines measured 0.00% N, therefore, there is not

C: N ratio available for these soils (Table 2.11). The 1982 and 1960 moraines showed measurable values at 0.01%N after ~57 years of development. At site in southern Norway observed concentrations of N in the mineral soil from 0.06% in the youngest moraine (50 – 70 years), rising to about 0.09%N in the 230-year old moraine (Vetaas, 1986).

The total N% for the hummocks is statistically significant between the 0 – 5 cm and 5 –

15 cm depths (ANOVA, p<0.0001) with all age groups combined. The Tukey groups show the same letter for all hummocks and the woodland reference soil, at both depths (Table 2.11). The highest %N was measured in the 1890 (0 – 5 cm) hummock at 1.15 %N. Depth functions show that most of the nitrogen of a mineral soil is located in the upper 20 cm, where major changes in its distribution occurs (Matthews, 1992; Crocker and Major, 1955). This study focused on the top

15 cm of the soil profile, when it could be sampled to that depth (i.e., hummocks and woodlands).

Overall the accumulation of N in the 0 – 15 cm of a soil, shows a trend in glacial moraines to increase the concentration rapidly after 40 years and the rate steadies after ~200 years of accumulation (Sondheim and Standish, 1983). The rapid accumulation of organic matter and N accelerates the processes of soil development in glacial moraines, but did not reach a steady state during the observed 180-year chronosequence (He and Tang, 2008). The Breiðamerkurjökull foreland did not reach a steady state either, however, the development of total N with increasing time is the expected trend, and with higher concentrations in the top 0 – 5 cm (Bernasconi et al.,

2011).

Table 2.11 Data table of average TN, SOC and C: N ratio values at different age-groups and by depth, with standard deviation in parentheses.

Chronosequence C:N Group TN (%) Tukey SOC (%) Tukey Age (Year) Ratio

2012 (5) 0 (0) c 0.02 (0) cd - 2004 (13) 0 (0) c 0.02 (0) d - 1994 (23) 0 (0) c 0.11 (0.02) cd - 1982 (35) 0.01 (0.01) bc 0.26 (0.09) cd 47:1 Moraines 1960 (57) 0.01 (0.02) bc 0.76 (0.43) bcd 55:1 0 -5 cm 1945 (72) 0.05 (0.02) bc 1.14 (0.63) bc 22:1 1930 (87) 0.07 (0.03) b 1.36 (0.62) b 20:1 1890 (127) 0.04 (0) bc 1.01 (0.07) bcd 23:1 Birch (Ref.) 0.6 (0.11) a 10.19 (1.57) a 17:1

1994 (23) 0.24 (0.03) a 3.49 (0.85) a 15:1 1982 (35) 0.62 (0.23) a 7.94 (3.08) a 13:1 1960 (57) 0.5 (0.26) a 6.78 (3.34) a 14:1 Hummocks 1945 (72) 0.46 (0.1) a 7.24 (1.60) a 16:1 0 -5 cm 1930 (87) 0.65 (0.36) a 8.14 (3.93) a 13:1 1890 (127) 1.15 (0.8) a 14.47 (8.55) a 13:1 Birch (Ref.) 0.6 (0.11) a 10.19 (1.57) a 17:1

1994 (23) 0.08 (0.1) a 1.01 (0.91) b 12:1 1982 (35) 0.05 (0.01) a 0.91 (0.08) b 18:1 1960 (57) 0.09 (0.08) a 1.11 (0.37) b 10:1 Hummocks 1945 (72) 0.07 (0.07) a 1.3 (0.73) ab 17:1 5 - 15 cm 1930 (87) 0.19 (0.12) a 2.41 (1.32) ab 14:1 1890 (127) 0.39 (0.3) a 4.31 (2.65) ab 12:1 Birch (Ref.) 0.28 (0.03) a 4.62 (0.56) a 17:1

*Means that do not share a letter are significantly different (Tukey Group).

2.4.6.2 Total SOC

Icelandic freely drained areas of Andosols, and commonly have total carbon (C %) up to

6% C in horizons not disturbed by intense land use or thick tephra deposits (Arnalds, 2008b), and above 12% C in Histic Andosols. Iceland’s total C pool in soils is estimated at 2.1 Petagrams of

C; the intact and fully vegetated soils have the largest potential to sequester SOC over the degraded soils (Lal, 2009). The SOC ranged in the moraines from 0.02% SOC to 1.36 % SOC, with the woodland reference soil at 10.19 % C in the top 0 – 5 cm (Table 2.11).

The ANOVA analysis provided evidence that there are significant differences between the means of the chronosequence moraines in the top 5 cm (Table 2.5). The lower values 0.02%

SOC were in the younger moraines at 2012 and 2004, then increases from 1994 at 0.11 % SOC to

1930 with 1.36% SOC (Table 2.11). The total SOC% declines in 1890 to 1.01% on average. He and Tang (2008) observed ~1.4%C in the ground moraines after 130 years of weathering. The gradient along the Damma Glacier chronosequence showed an increasing trend of total SOC (%) increasing with increasing site age values ranging from ~0.01% SOC to ~5 % SOC at the site age of ~150 years (Bernasconi et al., 2011). The SOC of the moraines show significantly lower percentages in the top 0 – 5 cm depth, than the hummocks and woodland reference (Figure 2.9).

Figure 2.9 Bar graph displaying the means of SOC at different age-groups, groups and depths.

The total SOC in the hummocks in the top 5 cm did not have significant differences between the mean values of each age-groups in the chronosequence (ANOVA, p-value = 0.121)

(Table. 2.8). The mean across the groups did not have different Tukey letter grouping from 1994 to the woodlands at 200 years (Table 2.11). The 1994 hummock (0 – 5 cm) measured 3.5% SOC, which increases to 7.9% SOC in 1982, followed by increasing values in 1945 and 1930, 7.2%

SOC and 8.1% SOC respectively (Table 2.11). The oldest hummock measured 14.5% SOC in the

0 -5 cm depth, which is greater than the woodland reference at 10.2% SOC. The hummocks lower depth (5 – 15 cm) ANOVA comparison showed significant differences between the age-groups with p-value at 0.0006 (Table 2.5). The lower depth (5 – 15 cm) values ranged from 0.9% SOC to

4.3% SOC in the seabird hummocks (Table 2.11). The hummocks (5 – 15 cm) from 1994 to 1945 share similar values from 0.9% SOC to 1.3% SOC (Table 2.11), then shows a different group means from 1945 to the birch woodlands with the Tukey pairwise comparisons. The woodland 5

– 15 cm depth measured 4.6% SOC; there is a significant difference between the woodlands top and lower depth (ANOVA, p-value<0.0001).

Four glacial forelands in southern Norway estimated values of SOC (%) from 0.10 –

36.1% SOC in the Haugabreen foreland and 0.10 – 4.53 % SOC in the Vestre Memurubreen foreland (Mellor, 1987). Although there is not one single explanation to account for the observed trends in total SOC and TN, it appears that the establishment of plants, and as the time progresses the morphological, physical, chemical and biological properties are intensified (Matthews, 1992).

2.4.6.3 C: N Ratio

The C: N ratio was based off a ratio of the total SOC% to the total N%, but ratios were not applicable to the moraines that measured 0% C. Cooler climates tend to have wider ratios with high accumulation of C, also the ratio is generally narrower for subsoils than the corresponding surface layers. The moraines (0 – 5 cm) C: N ratio values ranged from 17 to 55, with the highest ratio values in 1982 and 1960, 47 and 55 respectively (Table 2.11). The moraines from 1945 to 1890 had C: N ratio values ranging from 19 – 23 (Table 2.11). The hummocks from

0 – 5 cm measured C: N ratio values ranging from 13 – 17; there is less variation across the chronosequence for hummocks at the 0 -5 cm and the 5 – 15 cm. The lower depth (5 – 15 cm) of the seabird hummocks measured C: N ratio values from 10 – 18 (Table 2.11). As the decomposition processes continue, both C and N are now subject to loss – the C as CO2 and N as nitrates which are leached or absorbed by plants (Brady, 1974). At Glacier Bay, the N rapidly accumulated in the soil profile over the initial 100 years, followed by a fall in the amount of N for the next 200 years measured, but in contrast the SOC content remains steady after ~125 years

(Crocker and Major, 1955). This was reflected in the C: N ratio at Glacier Bay, Alaska. The C: N ratio of the Damma Glacier gradient vary between 12 and 30, with no significant trend across the chronosequence (Bernasconi et al., 2011), and the 0 – 5 cm layer had lower C: N ratios than the subsoil.

2.4.7 Mehlich III bio-availability of nutrients

2.4.7.1 Macro-nutrients

Several laboratories in the mid-west region of the United States have adopted, or expressed interest in adoption and analytical system based on extraction of all nutrients of interest using the Mehlich-III extractant (Mehlich, 1984), followed by simultaneous determination of all nutrients using inductively coupled spectroscopy (ICP) (Eckert and Watson, 1996). Very few published articles include data regarding soil test values obtained by the Mehlich III extraction in the sub-arctic region, or on diverse soil types. Michaelson et al. (1987) found that the relationship between quantities of P extracted by Bray 1-P was on average 66% less than the Mehlich III in volcanic ash soils, and 12% less in the loess soils (Cryorthents and Cryochrepts). Factors such as soil pH (H2O), Al content, and parent material (Michaelson et al., 1987) were concluded to implicate the differences in results. Sawyer and Mallarino (1999) presented that soils of pH 7.3 or lower had less variable results for Mehlich-3 P, Olsen P, and Bray-1 P, than the soils tested of pH

7.4 or higher. However, the results for the Alaskan volcanic soils (Michaelson et al., 1987) are consistent with the previous finding that the more strongly acidic extractants (Bray-2, Mehlich 1,

2, and 3) removed higher levels of P from volcanic ash soils. This method has not been calibrated for Icelandic soils, so there are potential unknown issues with interpreting the results for the moraines and hummocks, with variable charge and pH.

Seventeen elements have been demonstrated to be essential for plant growth, the essential elements must be present in forms usable by plants and optimal concentrations (Brady, 1974).

Also majority of plants develop N, P and K deficiencies more frequently than from other nutrients

(Dinkins and Jones, 2013). The macronutrients are used in relatively larger quantities than the micronutrients.

The moraines from have the highest concentration in 2012 at 1048.2 Ca μg g-1soil decreasing to with increasing chronosequence age, 2004, 1994, and 1982 respectively (Table

2.12). The values from 1960 to 1890 have similar means ranging from 285.7 Ca μg g-1 soil to

387.8 Ca μg g-1 soil (Table 2.12). The hummocks top depth (0 -5 cm) shared similar values, according to ANOVA and the Tukey pairwise comparison (Table 2.12). The hummocks values ranged from 839 μg Ca g-1 soil to 1661 μg Ca g-1 soil, and the woodlands 0 – 5 cm depth measured 1047 μg Ca g-1 soil (Table 2.12). The availability of Ca is similar across the seabird hummocks 5 – 15 cm chronosequence values ranging from 351.9 to 780 μg Ca g-1 soil (Table

2.12). The woodland 5 – 15 cm reference areas measured 375 μg Ca g-1 soil. Borkowska et al.

(2015) analyzed four soils, two podzols and cambisols (WRB), which compared the soil parameters in control and nesting sites of Corvus frugilegus.

The nutrient poor soils under pine trees (control site) (Borkowska et al., 2015) observed

391.6 ± 190.72 mg Ca kg-1 soil, while the nesting site determined 822.1 ± 480.70 mg Ca kg-1 soil.

The available Ca was greater than the control site, however the analysis was conducted with a different method (atomic absorption spectroscopy). The sites under the influence of seabirds exhibited a higher concentration of biological elements, when compared with the moraine sites.

The Breiðamerkurjökull samples showed similar findings for multiple elements.

Table 2.12 Data table of bio-available concentration of Ca, K, Mg, and P (Mehlich, 1984) in the moraine and hummock soils. Calcium Potassium Magnesium Phosphorus -1 -1 -1 -1 Chronosequence (Ca μg g soil) (μg K g soil) (μg Mg g soil) (μg P g soil) Age (Year) Mean St.Dev Tukey* Mean StDev Tukey Mean St.Dev Tukey Mean StDev Tukey 2012 (5) 1048.2 41 a 93.58 3.39 b 174.8 8.2 bc 20.64 0.33 a 2004 (13) 848.1 196.4 a 98.51 21.82 b 182.2 25.7 b 21.25 3.36 a 1994 (23) 743.9 105.7 ab 89.35 15.75 b 185.2 22.5 b 21.09 2.81 a 1982 (35) 524.2 61.2 bc 56.18 9.26 bc 150 13.2 bc 18.61 2.21 ab Moraines 1960 (57) 380.7 84.7 c 41.74 7.94 c 105.8 16.3 c 13.22 3.76 bc 0 - 5 cm 1945 (72) 387.8 60.1 c 55.01 11.34 bc 124.7 16.1 bc 10.69 3.06 c 1930 (87) 342.5 56.7 c 92.7 29.4 b 124.1 20.5 bc 12.1 1.35 c 1890 (127) 285.7 7.5 c 79.66 13.89 bc 106.7 4.6 c 11.69 1.42 c Birch (Ref.) 1047 424 a 316.2 53.2 a 369.9 117.8 a 9.05 6.49 c 1994 (23) 780.8 63.7 a 165.8 63.4 a 162.1 16.9 b 221.3 62 ab 1982 (35) 1380 367 a 133.83 17 a 167.2 30.2 b 365.9 75.2 a Hummocks 1960 (57) 855 292 a 124.1 84.9 a 226.6 75.1 ab 151.1 52.7 ab 0 - 5 cm 1945 (72) 839 345 a 161.3 107.1 a 214.4 17.4 ab 106 35.4 ab 1930 (87) 1208 549 a 149.2 104.3 a 228.8 76.2 ab 238 190 ab 1890 (127) 1661 967 a 169.2 95.9 a 342.6 100.4 ab 146.8 127.2 ab Birch (Ref.) 1047 424 a 316.2 53.2 a 369.9 117.8 a 9.05 6.49 b 1994 (23) 524.5 51.9 a 32.17 13.57 b 110.1 21.5 a 110.1 21.5 a 1982 (35) 508.7 70.2 a 25.71 5.15 b 107.4 18.3 a 107.4 18.3 a 1960 (57) 416.5 43.3 a 20.21 7.31 b 97 8.2 a 97 8.2 a Hummocks 1945 (72) 351.9 33.8 a 22.51 4.52 b 86.2 3.2 a 86.2 3.2 a 5 - 15 cm 1930 (87) 460 79.6 a 27.47 9.55 b 99.5 44 a 99.5 44 a 1890 (127) 780 500 a 39.5 19.3 b 134 28.7 a 134 28.7 a Birch (Ref.) 375 150.4 a 130.5 21.7 a 120.5 33.3 a 120.5 33.3 a *Means that do not share a letter are significantly different (Tukey Group)

The moraines concentration of K ranged from 41.7 to 98.5 μg K g-1 soil with similar means in the 2012, 2004, 1994, 1982, 1945 and 1890, according to the Tukey pairwise comparison (Table 2.12). The hummocks 0 – 5 cm concentration of K values ranged from 124.1 to 169.2 μg K g-1 soil, and the woodland reference area value of 316.2 μg K g-1 soil (Table 2.12).

The hummocks 5 – 15 cm depth had similar means from 1994 to 1890 (Tukey pairwise comparison) ranging from 20.2 to 39.5 μg K g-1 soil (Table 2.12). The woodland reference area in the lower depth measured 130.5 μg K g-1 soil, which is statistically significant from the other groups (Table 2.12). Borkowska et al., (2015) showed that the concentrations of K at control sites observed to be lower than the sites under the impact of birds nesting. Zwolicki et al., (2013) observed that the concentration of K (mg kg-1 soil) decreases in concentration with increasing distance from the influence of birds in the colony.

The Mg concentrations of the moraines (0- 5 cm) ranged across the chronosequence from

105.8 to 185.2 μg Mg g-1 soil (Table 2.12). The moraines Mg concentrations appear to show a trend of declining Mg availability with increasing age of chronosequence, with the highest availability in the woodland (0 – 5 cm) at 369.9 μg Mg g-1 soil (Table 2.12; Figure 2.10). The

Tukey pairwise comparison showed the significant means changing back and forth throughout the years in the chronosequence, with moraines 2012 to 1982 and 1945 to 1930 shared a grouping letter with values ranging between 124.1 to 185.2 μg Mg g-1 soils (Table 2.12). The 1960 and

1890 (0 -5 cm) moraines determined similar values, 105.8 and 106.7 μg Mg g-1 soil respectively

(Table 2.12).

The hummocks did show significant differences in the 0 – 5 cm chronosequence years, with values ranging from 162.1 to 342.6 μg Mg g-1 soil (Table 2.12). The first two hummocks sampled 1994 and 1982 shared a letter in the Tukey pairwise comparison, at 162.1 and 167.2 μg

Mg g-1 soil respectively (Table 2.12). The chronosequence ages from 1960 to the woodlands share

83 a Tukey letter for grouping significant means; the Mg availability decreases from 1960 to 1945 from 226.6 to 214.4 μg Mg g-1 soil, and then followed by increasing values with increasing years

(Table 2.12). When the seabird hummocks are plotted, the availability of Mg in the soil appears to be showing a trend of increase with increasing number of years (Figure 2.10).

The seabird hummock lower depth did show a significant difference between the 0 -5 cm depth and the 5 – 15 cm depth (ANOVA, p-value <0.0001), the average value of all years combined at 0 -5 cm is 244.5 μg Mg g-1 soil and 5 – 15 cm is 107.83 μg Mg g-1 soil. However, there is not a significant difference between the age-groups of the lower depth (5 – 15 cm, hummocks) chronosequence, with values ranging from 86.2 to 134 μg Mg g-1 soil (Table 2.12).

The hummocks 5 – 15 cm shows a trend of consistent availability of Mg, with the greatest concentration in 1890 at 134 μg Mg g-1 soil (Table 2.12). Mg is an integral part of the chlorophyll molecule and co-factor of many enzymes (Jenny, 1980). When Borkowska et al. (2015) looked at the influence of bird nesting, the control site exhibited 124.2 ± 125.47 mg Mg kg-1 soil and higher concentrations of 153.9 ± 164.15 mg Mg kg-1 soil in the nesting soils.

The availability of P for moraine sites range across the chronosequence from 10.7 to

21.25 μg P g-1 soil, and the woodland 0 -5 cm measured 9.05 μg P g-1 soil. The trend for the moraines shows a steady decrease in available P with increasing years of chronosequence (Figure

2.10). This would be expected with P-retention analysis demonstrating increasing amount retained with increasing year of chronosequence (Figure 2.7). The moraines (0 – 5 cm) 2012,

2004, 1994 and 1982 share a similar mean (Tukey Group) ranging in availability from 18.6 to

21.3 μg P g-1 soil (Table 2.12). The moraines chronosequence age from 1960 to 1890 shared a similar Tukey group with values ranging from 10.69 to 13.22 μg P g-1 soil (Table 2.12). The woodland at 0 -5 cm measured the lowest concentration of available P across the moraine and hummock (0 – 5 cm) chronosequence at 9.05 μg P g-1 soil (Table 2.12).

Concentrations of P for the hummock soils top 5 cm exhibited values ranging from 106 to

365.9 μg P g-1 soil (Table 2.12). The Tukey grouping shows similarities between many groups in the 0 -5 cm hummock chronosequence with some variation of groups, however there was only one grouping for the 5 – 15 cm hummocks (Table 2.12). For the lower depth of the hummocks, concentrations of available P ranged from 55.8 to 249 μg P g-1 soil (Table 2.12). The woodland 5

– 15 cm depth measured the lowest availability of P at 1.12 μg P g-1 soil (Table 2.12). The lower depth for the hummocks shows a variable trend with the greatest availability of P in the oldest hummocks (i.e., 1930 and 1890) (Table 2.12).

The concentration values of S for the moraines range from 4.41 to 24.78 μg S g-1 soil with the woodland reference at 13.32 μg S g-1 soil (Table 2.13). The availability of S in the moraine soils appears to follow a trend of high initial values followed decreasing concentrations with increasing number of years until 1945 where the concentrations increase (Figure 2.10). The

Tukey grouping follows this trend of increasing and decreasing values (Table 2.13). The highest concentration across the moraine chronosequence of available S is in the 2004 samples at 24.8 μg

S g-1 soil and the lowest value is in 1960 at 4.41 μg S g-1 soil.

The hummocks at 0 – 5 cm did not have significant differences between the age-groups for S, and concentrations ranged from 8.7 to 19.5 μg S g-1 soil (Table 2.13). The trend of the S availability in hummocks appears to show an increasing concentration with time (Figure 2.10), which is different than the trend seen in the moraines. At the lower depth (5 – 15 cm) the hummocks values ranged from 4.4 to 11.75 μg S g-1 soil across the chronosequence (Table 2.6).

There is some variation between group means with the Tukey pairwise comparison, and appears to follow a similar trend as the top 5 cm measurements (Table 2.6).

The trends of each of these nutrients were analyzed across the chronosequences. The moraines did demonstrate a significant difference between values of the chronosequence for these

85 macro-nutrients (Table 2.5). The trends of Ca and Mg concentration decreases with increasing terrain age, however this decline is not significant (Figure 2.10). The K, P, and S of the moraines show significant difference in means of the chronosequence, however the trend doesn’t appear to be significant in increase nor decrease of concentration. The S concentration in the moraines is high initially and rapidly declines, followed by steadier fluctuation of concentrations (Figure

2.10).

2.4.7.2 Micro-nutrients

Micronutrients include Al, B, Cl, Cu, Fe, Mn, Mo, Na, Ni, and Zn, all of which are naturally presented in most soils, but in lower quantities than the macro-nutrients (Dinkins and

Jones, 2013). The ANOVA analysis compared the significance between the groups including the moraines, hummocks and woodland reference area, and showed that Al, B, Fe, Mn, Na, and Zn had p-values <0.0001, rejecting the null hypothesis in favor of the alternative that states that not all means are equal (Table 2.5). ANOVA comparison between the groups determined there was not a significant difference between the means for Cu and Mo with p-values greater than the level of significance (α = 0.05), 0.368 and 0.558 respectively (Table 2.5).

When ANOVA analysis compared the difference between chronosequence age-groups for each nutrient, with the depths and groups combined, there was a significant difference between means for Al, B, Cu, Fe, Mn, Na, and Zn with p-values <0.005 (Table 2.5). The only micro-nutrient that did not show differences across the chronosequence was Mo, with a p-value =

0.736 (Table 2.5). The ANOVA analysis compared the group means of nutrients across the chronosequence age for moraines (0 -5 cm) showed that there was a significant difference between means for Al, Cu, Fe, Mn, Na, and Zn (p-value<0.0001), but assumed equal means for B and Mo concentrations due to p-values greater than α, 0.057 and 0.343 respectively (Table 2.5).

Results from ANOVA comparing the chronosequence of hummocks (0 -5 cm) showed that Al, B, Cu, Fe, Mn, and Na showed low p-values, thus these variables have significant difference of means at different age-groups, including the woodland reference (Table 2.5).

Several micro-nutrients had p-values greater than the level of significance (α = 0.05) including,

Mo and Zn (Table 2.5). ANOVA analysis could not be conducted over Mo and Zn, due to lack of precise values above the limit of detection. When the hummocks (5 – 15 cm) micro-nutrients are compared using ANOVA, there was a significant difference between means for Al, B, Cu, Fe, Mn and Na, with p-values less than the level of significance (Table 2.5).

The concentrations of available Al in the moraine soils (0 – 5 cm) ranged from 661.2 to

1,026.3 μg Al g-1 soil and the woodland reference (0 – 5 cm) at 200 years measured 1,546.5 μg Al g-1 soil (Table 2.17). The 2012 moraine measured concentration of 661.2 μg Al g-1 soil, followed by increasing concentration of Al from 2004 to 1994 (Table 2.17). Then the concentration decreases in 1982, and then continues to increase in concentration until 1930 the highest concentration of Al in the moraines at 1026.3 μg Al g-1 soil (Table 2.17). The moraines trend of

Al availability shows a trend of increasing concentrations with increasing chronosequence age.

The hummocks at 0 – 5 cm determined a range of Al concentrations from 848.8 μg Al g-1 soil in the 1994 hummock to 1250.8 μg Al g-1 soil in the 1890 hummock (Table 2.17). The means of each age-group increase for the Al concentration across the chronosequence from age-group to the next (Table 2.17). The hummocks in the lower depth follows a similar trend of increasing concentration of Al with increasing chronosequence age. The values for the hummocks (5 – 15 cm) availability ranged from 711.4 μg Al g-1 soil in 1994 to 1330.5 μg Al g-1 soil in 1890; the woodland at this depth measured 1763.5 μg Al g-1 soil (Table 2.17).

The B availability of the moraines ranged between <0.040 μg B g-1 soil to 0.84 μg B g-1 soil, with the woodland (0 – 5 cm) concentration is 0.923 μg B g-1 soil (Table 2.14). There is one

Tukey group for all age-groups across the chronosequence for the moraines (Table 2.14). The hummocks at 0 – 5 cm exhibited concentrations from 0.97 to 1.59 μg B g-1 soil (Table 2.14) and appears to have a more variable trend of concentrations. The lower depth of the hummocks (5 –

15 cm) had a less variable trend with a range of values from 0.50 to 1.59 μg B g-1 soil (Table

2.14). The concentration of B in the hummocks (5 – 15 cm) increased from 1994 to 1945, which is the highest concentrations in the lower depth (Table 2.14). The concentrations decreases from

1945 to 1890 at 1.42 μg B g-1 soil, and the woodland (5 – 15 cm) reference determined 1.01 μg B g-1 soil (Table 2.14).

Table 2.13 Data table of bio-available concentration of Al, Fe, Na, and S (Mehlich, 1984) in the moraine and hummock soils.

Chronosequence Aluminum (μg Al g-1 soil) Iron (μg Fe g-1 soil) Sodium (μg Na g-1 soil) Sulfur (μg S g-1 soil) Age (Yr) Mean StDev Tukey* Mean StDev Tukey Mean StDev Tukey Mean StDev Tukey 2012 (5) 661.2 25.6 d 535 40.1 ab 99.74 7.31 abc 22.65 12.95 ab 2004 (13) 819 128.1 cd 577.4 15.6 a 112.63 9.34 a 24.78 6.79 a 1994 (23) 854.1 89.1 bcd 520.5 16.8 bc 111.03 3.07 ab 9.28 4.61 c Moraines 1982 (35) 787.7 81.5 d 475.2 22.1 c 100.41 9.16 abc 4.97 0.64 c 0 - 5 cm 1960 (57) 806.4 98.7 cd 423.2 18.7 d 81.93 4.48 d 4.41 1.57 c 1945 (72) 985.8 70.6 bc 422.4 22 d 97.89 5.13 bc 8.8 2.95 c 1930 (87) 1026.3 81.6 b 390.5 31.5 de 96.87 7.13 c 12.94 3.23 bc 1890 (127) 989.1 16.12 bc 373.2 13.7 e 95.11 6.37 cd 11.94 1.03 bc Birch (Ref.) 1546.5 140.1 a 256.3 20.4 f 65.17 3.04 e 13.32 2.27 bc 1994 (23) 848.8 111.7 c 477.5 2.5 a 74.82 6.64 b 8.7 1.99 a 1982 (35) 975.2 126.1 bc 455.2 0.9 ab 93.51 7.66 ab 13 3.14 a 1960 (57) 1011.6 94 bc 460.9 19.2 ab 74.37 13.12 b 11.19 3.89 a Hummocks 1945 (72) 1093.8 0 - 5 cm 91 bc 420 32.9 b 78.19 10.87 ab 14.61 2.12 a 1930 (87) 1134 202 bc 430.3 20 ab 90.4 19 ab 11.98 5.1 a 1890 (127) 1250.8 136 ab 423.1 17.2 b 135.5 49.5 a 19.5 7.74 a Birch (Ref.) 1546.5 140.1 a 256.3 20.4 c 65.17 3.04 b 13.32 2.27 a 1994 (23) 711.4 158.4 d 501 46.9 ab 66.96 11.83 ab 4.38 0.97 b 1982 (35) 869.5 139.1 cd 529.3 17.1 a 74.38 5.42 a 6.29 0.6 ab 1960 (57) 956.51 11.58 cd 506.6 11.4 ab 59.25 5.07 ab 5.53 0.7 ab Hummocks 1945 (72) 1138.1 5 - 15 cm 83.7 bc 504.7 26.1 ab 59.01 3.43 ab 6.73 2.48 ab 1930 (87) 1257.1 133.5 b 463.2 23.6 ab 62.56 13.06 ab 9.43 3.75 ab 1890 (127) 1330.5 81.7 b 441.2 12.5 b 69.75 17.07 a 11.75 4.1 a Birch (Ref.) 1763.5 37 a 191.4 18.8 c 40.53 6.9 b 7.96 2.51 ab *Means that do not share a letter are significantly different (Tukey Group) 89

Table 2.14 Data table of bio-available concentration of B, Cu, Mn, Mo, and Zn (Mehlich, 1984) in the moraine and hummock soils.

Manganese Molybdenum Zinc Boron (μg B g-1 soil) Copper (μg Cu g-1 soil) (μg Mn g-1 soil) (μg Mo g-1 soil) (μg Zn g-1 soil) Chronosequence Mean StDev Tukey Mean StDev Tukey Mean StDev Tukey Mean StDev Tukey Mean StDev Tukey 2012 (5) 0.44 0.46 a 3.72 0.58 ab 24.28 1.06 ab <0.010 - a 4.54 3.41 abc 2004 (13) 0.84 0.36 a 4.66 0.43 a 27.86 4.86 a <0.010 - a 11.80 3.51 a 1994 (23) 0.84 0.24 a 3.57 0.78 ab 24.35 2.23 ab 0.03 - a 15.65 0.79 abc

1982 (35) 0.39 0.02 a 3.34 0.51 ab 21.19 1.77 b 0.02 0.01 a 8.60 7.53 c

5 cm

1960 (57) 0.21 0.08 a 4.69 0.97 a 13.46 2.29 c 0.02 0.00 a 1.65 0.83 c

–

Moraines 1945 (72) <0.040 - a 3.80 1.14 ab 11.89 2.02 c 0.02 0.01 a 1.18 0.66 c 1930 (87) <0.040 - a 3.07 1.12 ab 10.86 1.90 c <0.010 - a 0.99 0.78 abc 1890 (127) 0.45 0.44 a 2.21 0.11 b 9.50 2.20 c 0.02 0.01 a 9.90 7.26 ab Birch (Ref.) 0.92 0.20 a 2.92 0.55 ab 28.47 6.28 a 0.02 0.01 a 13.18 2.48 bc 1994 (23) 1.01 0.25 bc 2.20 0.41 ab 16.45 2.26 b 0.03 0.02 a 6.53 7.52 a 1982 (35) 0.97 0.16 c 1.48 0.49 b 9.21 2.43 bc 0.01 0.00 a 3.63 0.66 a

1960 (57) 1.50 0.30 ab 3.25 1.13 a 11.97 1.52 bc 0.02 - a 0.37 0.19 a

5 cm

1945 (72) 1.41 0.04 abc 3.10 0.58 ab 10.34 2.09 bc 0.04 - a 2.19 2.91 a

–

0 1930 (87) 1.59 0.05 a 1.77 0.60 ab 8.61 2.22 bc 0.03 0.02 a 1.04 0.81 a

Hummocks 1890 (127) 1.39 0.12 abc 1.39 0.35 b 6.54 1.75 c 0.02 - a 1.34 0.11 a Birch (Ref.) 0.92 0.20 c 2.92 0.55 ab 28.47 6.28 a 0.02 0.01 a 13.18 2.48 a 1994 (23) 0.70 0.37 b 5.19 0.22 a 16.57 3.90 ab <0.010 - a <0.013 - - 1982 (35) 0.99 0.08 ab 4.61 0.51 ab 16.40 2.11 abc <0.010 - a 0.32 0.15 -

1960 (57) 1.47 0.11 a 5.03 2.06 a 12.85 0.87 bcd <0.010 - a <0.013 - -

15 15 cm 1945 (72) 1.50 0.04 a 5.27 0.41 a 11.39 3.58 bcd <0.010 - a <0.013 - -

– 1930 (87) 1.43 0.10 a 3.24 1.82 ab 7.38 2.79 cd <0.010 - a <0.013 - -

Hummocks 1890 (127) 1.42 0.13 a 1.65 0.65 b 4.07 1.46 d <0.010 - a 1.73 1.78 - Birch (Ref.) 1.01 0.45 ab 3.69 0.03 ab 22.86 5.67 a <0.010 - a <0.013 - -

*Means that do not share a letter are significantly different (Tukey Group)

The ANOVA analysis determined that there was not a significant difference of means for

Cu availability in the three groups of the chronosequence (Table 2.5). The Cu concentrations of the moraines range from 2.21 to 4.69 μg Cu g-1 soil (Table 2.14). The availability of Cu is significantly different between the moraine age-groups, there is two groups of significant means that fluctuate back and forth. The availability of Cu appears to follow a trend of decreasing concentrations with increasing years (Figure 2.11), but the spread of data points appears to be greater. The hummocks (0 -5 cm) availability of Cu ranged between 1.39 to 3.25 μg Cu g-1 soil

(Table 2.14). It is interesting that in each chronosequence (i.e., moraine, hummock 0 – 5 cm, 5 –

15 cm) the 1960 age-group has the highest concentration of Cu, including the woodland reference areas (Table 2.14). There is a fluctuation of increasing values to decreasing and vice versa across the three different chronosequences analyzed. The hummocks (5 – 15 cm) concentrations ranged from 1.65 to 5.27 μg Cu g-1 soil. The Cu is an essential element for both plants and animals, commonly occurs at levels of 5 to 30 μg g-1 soil (Shoji et al., 1993).

The ANOVA analysis determined that there was a difference of means for Fe in the three groups of the chronosequence (Table 2.5). The Fe concentrations in the moraines showed significant difference of means between the age-groups of the chronosequence, the values range from 256.3 μg Fe g-1 soil in the birch woodlands to 577.4 μg Fe g-1 soil in the 2004 age-group

(Table 2.13). There seems to be a trend of decreasing Fe availability with increasing number of years (Figure 2.11). The 2012 and 2004 moraines share similar means then decreases in the 1994 and 1982 moraines with a significant letter with the Tukey pairwise comparison (Table 2.13). The moraine average Fe concentration continues to decrease from 1960 at 423.2 μg Fe g-1 soil to 373.

2 μg Fe g-1 soil in the 1890 moraine (Table 2.13).

The hummocks in both depths follow similar linear trends of decreasing concentrations of

Fe with increasing chronosequence age (Table 2.13). The top depth for the hummocks values

91 ranged from 477.5 μg Fe g-1 soil in 1994 to 420 μg Fe g-1 soil (Table 2.13). There is a decrease in concentrations of Fe in the hummocks (0 – 5 cm) from 1994 to 1945, then the availability increases in 1930, and proceeds to decline for the remaining age-groups (Table 2.13). The hummocks lower depth (5 – 15 cm) concentration of available Fe ranges from 441.2 to 529.3 μg

Fe g-1 soil (Table 2.13). The Tukey pairwise comparison shows that the woodland reference area at 5 – 15 cm is significantly different from the other age-groups, measuring 191.4 μg Fe g-1 soil

(Table 2.13). The trend of the available Fe in the hummocks (5 – 15 cm) shows similar concentrations in the 1994 to 1930 samples with a decrease of means in the 1890 sample (Table

2.13).

The concentration of Mn in the moraines ranges from 9.5 to 27.86 μg Mn g-1 soil in the moraines from 2012 to 1890 (Table 2.14). The trend of availability in the moraines seems to decrease in concentration with increasing years (Figure 2.11). The 2012, 2004, and 1994 shared similar means ranging from 24.3 to 27.9 μg Mn g-1 soil (Table 2.14). The concentration of Mn decreases from 1994 to 1890 with a lower concentration of 9.5 μg Mn g-1 soil (Table 2.14). The reference area of woodlands (0 – 5cm) shares Tukey grouping with the youngest moraines including, 2012, 2004, and 1994 (Table 2.14), and had a concentration of 28.5 μg Mn g-1 soil.

The average mean concentration of Mn for the two depths of the hummocks samples did not show significant difference (ANOVA, p-value=0.996) between the groups. The hummocks (0

– 5 cm) showed a trend of generally decreasing concentration of Mn with increasing years. The

Mn concentration values range from 6.5 μg Mn g-1 soil in 1890 to 16.45 μg Mn g-1 soil in 1994

(Table 2.14). There is a similar trend of decreasing concentration of Mn in the hummocks lower depth (5 – 15 cm), with the highest concentration in 1994 at 16.6 μg Mn g-1 soil to the lowest concentration in 1890 at 4.1 μg Mn g-1 soil (Table 2.14). The woodland reference (at 5 – 15 cm)

92 measured 22.9 μg Mn g-1 soil and is similar to the 1994 and 1982, according to the Tukey pairwise comparison (Table 2.14).

Molybdenum is one of the micro-nutrients plants require for normal growth. The micronutrients are only required in very small amounts, as little as 50 g ha- of molybdenum will satisfy the needs of most crops (Alt and Milham, 2018). The concentrations for the analysis of Mo in the glacial moraines and hummocks were quite low, with this analysis samples were generally below the LOD; thus their precise concentrations are unknown and negligible (Table 2.14). However, there were a few samples at both depths that were above the LOD for available Mo.

The values of Mo concentrations ranges from <0.01 to 0.034 μg Mo g-1 soil, with the woodland 0

– 5 cm depth determined 0.017 μg Mo g-1 soil. The 2012 and 2004 moraines were <0.01 μg Mo g-

1 soil and increases to 0.034 μg Mo g-1 soil in 1994, then decreases to 0.017 μg Mo g-1 soil in

1960 (Table 2.14). The concentrations across the moraines chronosequence is not significantly different between the age-groups (Table 2.5). The hummocks (5 – 15 cm) did not have any observations above the LOD of <0.01 μg Mo g-1 soil (Table 2.14).

The concentration of Na in these chronosequences show a weak trend of decreasing concentration of Na with increasing years (Figure 2.11). The moraines Na availability ranged in concentration from 81.9 to 112.6 μg Na g-1 soil (Table 2.13). There are similar means in 2012,

2004, 1994, and 1982 ranging from 99.7 to 100.4 μg Na g-1 soil, then decreases significantly in

1960 to 81.9 μg Na g-1 soil (Table 2.13). The last three moraines in the chronosequence – 1945,

1930, and 1890 – concentration values ranging from 97.9 to 95.1 μg Na g-1 soil (Table 2.13). The woodland soil at 0 – 5 cm determined 65.2 μg Na g-1 soil, and the lower depth at 40.5 μg Na g-1 soil (Table 2.13).

The hummock’s top 5 cm Na concentrations ranged from 74.4 to 135.5 μg Na g-1 soil

(Table 2.13) with significant differences between the age-groups using ANOVA analysis (Table

2.5). The hummock’s (0 – 5 cm) availability of Na fluctuates between increasing and decreasing concentrations across the chronosequence. The concentration of the 1994 hummock increases to

1982, followed by a decrease in 1960 and then continued increase in availability until 1890

(Table 2.13). The Na concentration in the lower depth (5 – 15 cm) of hummocks also fluctuated between increasing and decreasing availability across the chronosequence. The Na availability in the 5 – 15 cm depth hummocks ranged from 59.01 to 74.4 μg Na g-1 soil across the chronosequence (Table 2.13). The hummocks trend of Na increases from 1994 to 1982 at 74.4 μg

Na g-1 soil, followed by a decrease in Na availability in the next two age-groups 1960 and 1945

(Table 2.13). The hummocks 5 – 15 cm Na concentration increases in the last two hummocks at

1930 and 1890. The woodland reference soil at 5 – 15 cm measured 40.53, a significant mean from the hummocks measurements, when looking at the Tukey pairwise comparison of significance (Table 2.13).

The availability of Zn had significant means between the different groups (ANOVA, p- value<0.0001). The moraines concentrations of Zn range from 0.99 to 15.7 μg Zn g-1 soil, and the reference woodland (0 – 5 cm) availability at 13.2 μg Zn g-1 soil. The concentration of Zn fluctuate between different age-groups along the chronosequence. The 2012 moraine measured

4.5 μg Zn g-1 soil then increases in 2004 and 1994 to 15.7 μg Zn g-1 soil (Table 2.14). The availability decreases in 1982 from 8.6 μg Zn g-1 soil to 1930 at 0.99 μg Zn g-1 soil

The concentrations of Zn in the hummocks were quite low, with analysis samples generally below the LOD; thus their precise concentrations are unknown and negligible (Table

2.14). The hummocks (0 – 5 cm) concentration of Zn ranged from 6.53 μg Zn g-1 soil in 1994 to

0.37 μg Zn g-1 soil (Table 2.14). The concentration of the first two hummocks have the highest Zn availability, and the remaining years have values ranging from 0.37 to 2.19 μg Zn g-1 soil (Table

2.14). The lower depth of the hummocks did not have many observations that had values above

94 the LOD, but there were measurable values in 1982 at 0.32 μg Zn g-1 soil and in 1890 at 1.73 μg

Zn g-1 soil (Table 2.14). The remaining age-groups did not have concentrations greater than 0.013

μg Zn g-1 soil (Table 2.14). Zn is an essential element at low concentrations, it normally occurs at levels of 20 to 100 in plants, and has been recognized in a variety of agricultural plants grown on

Andosols (Shoji et al., 1993).

Micronutrients are nutrients found in relatively low concentrations (<100 mg kg-1) in organic tissue (Chesworth, 1991). Many deficiencies of various micronutrients in Andosols have been reported, the most prevalent among them are Cu, Zn, and Co (Shoji et al., 1993). The abundance and availability of these micronutrients in Andosols are dependent on the abundance of the elements in the parent tephras. Nanzyo (2002) reported that the mean content of 12 major elements (C, N, Na, Mg, Al, Si, P, K, Ca, Ti, Mn, and Fe) was more than 1 g kg-1 soil and the remaining were less than that.

The concentrations of the micronutrients in the Breiðamerkurjökull moraine soils are variable in their trends across the chronosequence. The Na, Mn, and Fe show generally decreasing concentrations of ions with increasing terrain age (Figure 2.11). The Al concentration demonstrates a trend of increasing availability with the years of chronosequence increasing

(Figure 2.11). The B, Zn, Cu and Mo show do not show a significant trend of either increasing or decreasing availability with time (Figure 2.11).

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58. Walker, L. R., Wardle, D. A., Bardgett, R. D. and B. D. Clarkson. 2010. The Use of Chronosequences in Studies of Ecological Succession and Soil Development. Journal of ecology 98(4): 725–736 pp. 99

59. Walkley, A. and I. A. Black. 1934. An examination of Degtjareff method for determining soil organic matter and a proposed modification of the chromic acid titration method. Soil Sci. 37: 29-37.

60. Zwolicki A, Zmudczynska-Skarbek K.M., Iliszko L, and L. Stempniewicz. 2013. Guano deposition and nutrient enrichment in the vicinity of planktivorous and piscivorous seabird colonies in Spitsbergen. Polar Biol 36:363–372.

61. Zwolicki, A., Barcikowski, M., Barcikowski, A., Cymerski, M., Stempniewicz, L., and P. Convey. 2015. Seabird colony effects on soil properties and vegetation zonation patterns on King George Island, Maritime Antarctic. Polar Biol. 38:1645–1655.

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Chapter 3. DISCUSSION OF RESULTS FROM THE BREIDAMERKURJOKULL GLACIAL FORE-FIELD

3.1 Introduction to discussion of results

The Breiðamerkurjökull is an outlet glacier in Vatnajökull ice cap in southeast Iceland, and has been retreating due to a warming climate since the Little Ice Age (LIA). Storrar et al.

(2015) presented mapping of Breiðamerkurjökull from various aerial photographs in order to map the layout of eskers, identifying significant ice margin positions at 1890, 1930, 1945, 1954, 1965,

1980, 1988, 1994, 1998, 2007 and 2012. The proglacial area of Breiðamerkurjökull consists of glacial sediments deposited directly from glacier ice (moraines). The moraine material is a mixture of ground volcanic rocks and glassy tephra, which covers outlet glaciers to a significant extent due to relatively frequent events of tephra fall during sub-glacial eruptions

(Vilmundardóttir et al., 2015).

The three factors that predominately influence the soil environment in Iceland includes:

1.) frequent volcanic activity and volcanic nature of soil parent materials, 2.) cold maritime climate with intensive cryogenic processes, and 3.) active soil erosion by wind, water and gravity

(Arnalds and Kimble, 2001). Andosols are soils of active volcanic areas, they exhibit distinctive soil properties and unique natural resources. The parent materials are made up of volcanic materials and when they are exposed to weathering, short-range order minerals, such as allophane, imogolite and ferrihydrite are formed, and sometimes metal – humus complexes, especially with organic matter (Arnalds and Stahr, 2004). These materials that give the Andosols their distinctive properties is termed andic properties. Examples of these include: low bulk density, variable charge, high water retention and phosphate absorption (Arnalds, 2004). The

Andosols are the most common soils of Iceland at ~ 28,280 km2, however erosion of Andosols has been a concern since the last part of the 19th century (Arnalds, 2008).

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The chemical properties of the Andosols reflect high surface area soils, due to the clay minerals and organic materials that accumulate. Icelandic soils differ from most other soils of

Europe and the world because of a unique soil environment, they also make up the largest area dominated by Andosols (Arnalds, 2007). These soils evolve under many reactions taking place and are functionally related to soil-forming factors (Jenny, 1941), however pedologists have had difficulties quantifying soil-parent material functions. The Icelandic soils are youthful due to the frequent additions of new materials to the top of soil profiles, and with the cold climate to limit the rates of pedogenic processes. This chapter will discuss the results from Chapter 2, and the significant conclusions that were drawn from this research.

This thesis addresses three linking concepts including: 1.) the soil development of Andic properties in glacial moraine material, 2.) the trends of bio-available nutrients and soil chemical properties over time, and 3.) the influence of seabirds in soil development at the site. Initially the research questions addressed how nutrients and chemical properties are developing with increasing age of moraine and exposure to soil forming factors, and if there is a significant difference between the moraine soils and the bird hummocks. However with analysis of results, the question arose whether or not these two chronosequences were actually developing under the same soil forming factors and processes. The hummocks appear to develop very rapidly, even within a couple decades of glacial recession. Which could be an indicator that the birds are not only providing organic matter to the site, but the birds assist in creating an environment where vegetation is established and then the soil accumulates rapidly.

The following discussion will address the moraines chronosequence results (from

Chapter 2) separately from the hummocks chronosequence, and then compare the two with overarching conclusions from the study. This chapter will be concluded with limitations of the

102 study, as well as, some discussion of areas of investigation for future research at the

Breidamerkurjokull glacial fore-field.

3.2 Trends across the moraine chronosequence

Soils chronosequences are valuable tools for investigating rates and directions of soil and landscape evolution. Post-incisive chronosequences are the most common type of chronosequence, including glacial moraines, lava flows and alluvial fans, etc., and register pedogenic change over time-scales ranging from years to millions of years (Huggett, 1998).

Matthews (1992) conducted a comprehensive review of ecological research on glacier forelands across a world-wide literature, as a geoecological approach to soil development. In front of a retreating glacier, the time factor is the major control on the spatial sequences in vegetation and soils. Walker et al. (2010) presents that chronosequences are multi-faceted, and can be used to track many ecosystem patters and processes developing through time, some of which may develop independently of each other. However, spatial variability compounds the difficulty of interpreting temporal variability within sites and suggests the need for caution. Chronosequence studies in Iceland have been useful in understanding the development of young soils (i.e. Stanich,

2013; Vilmundardóttir et al., 2014; 2015; Ritter, 2008).

Vilmundardóttir et al. (2015) conducted analysis at the Breiðamerkurjökull glacial foreland – across the same chronosequence as this study – with analysis of the vegetation coverage, soil morphology, profile description, bulk density, LOI (%), SOC (%), Total N (%), C:

N, pH (H2O) and pHNaF. Further analysis of the Breiðamerkurjökull foreland, builds a more extensive and interdisciplinary study of the chronosequence and overall mechanisms of the soil landscape. The moraines are sampled from 0 – 5 cm, due to the early stage of development the horizons have not developed soil past that depth (Figure 3.1). The establishment of vegetation is

103 important for building soil in the moraines, the vegetation collects materials blown around and starts to accumulate (Vilmundardóttir et al., 2015; Arnalds and Kimble, 2001; Dugmore et al.,

2009).

Figure 3.1 Image of 1960 moraine sampled from 0 – 5 cm, showing coarse large rocks.

The trends of the moraines across the chronosequence showed significant difference between the age-groups (using one-way ANOVA) for soil pHH2O, pHNaF, P-retention, SOC, TN, available NH4-N, available ions Ca, K, Mg, P, Al, Cu, Fe, Mn, Na, S and Zn (Table 2.5). The soil pH (H2O) measured in the moraines is showing a trend of early soils with an alkaline tendency. 104

Which as the chronosequence age increases the pH (H2O) declines to a more acidic soil in the oldest moraines, and developed woodland. This aligns with the trend observed in other Icelandic

Andosols, as well as other glacial moraines in similar climates. Vilmundardóttir et al. (2014) demonstrated that soil pH (H2O) declined rapidly and was the only soil property that attained a steady state compared to that under the birch forest.

The youngest moraine soils presented the lowest pHNaF values at 8.1 with a trend of increasing pH with increasing chronosequence age, to a peak value in the 1960 moraines at 9.6

(Figure 2.6). When a 1 M pHNaF is measured greater than 8.2 at 2 minutes, the NaF solution is a strong indicator (in non-calcareous soils) that short-range order minerals dominate the soil exchange complex (USDA-NRCS, 2004). The pHNaF measured in eight other pedons of Icelandic soils (Arnalds and Kimble, 2001) determined values ranging from 9.4 to 10.1, at various depths.

The soils showing higher pH values with NaF solution, suggest andic properties, and such values are similar or higher under full vegetative cover (Arnalds et al., 1995). The increasing pHNaF values over the chronosequence could be an indication on the formation of allophane within the soil profile (Vilmundardóttir et al., 2015). The moraines at Skaftafellsjökull showed a more inconsistent trend initially alkaline at 8.9 decreasing to 8.3 in the oldest moraines

(Vilmundardóttir et al., 2014), however they are in a similar range of values and age since deglaciation.

A common feature observed in Andosols is their large capacities to adsorb phosphorus

(P) (Wada, 1985). The mechanisms for P-retention in an Andosol has been based primarily on the synthetic aluminosilicates and hydrous oxides, and only recently on allophanic soil material

(Beck et al, 1999). The amount of P retained in moraines follow a trend of low P-retention in the youngest age-groups, with an increasing percentage with years of soil development. Moraines values ranged from 12% to 26.1% P-retained, with significant differences between the groups.

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There have been few investigations of the P content of glacier foreland soils, which makes it difficult to compare because different fractions have been analyzed using different extraction methods (Matthews, 1992). Understanding of how P transforms across a chronosequence requires a consideration of the initial conditions, physicochemical processes as well as biological mineral cycling. Plants can absorb soluble P and weakly bound forms of P, however in most Andosols with weathering products such as non-crystalline Al and Fe materials, resulting in an insoluble P.

Thus, even young Andosols may show P deficiencies for most agricultural plants, and require applications of phosphate fertilizers (Shoji et al., 1993). The results of this analysis do provide evidence that the moraine soils are developing towards andic properties.

The results of TN and SOC analysis exhibited values within the range presented by

Vilmundardóttir et al. (2015). The TN values remained low in the moraines reaching a peak value in the 1930 moraine of 0.07% N. The SOC in the moraines is low initially at 0.02% SOC increasing to a peak in 1930 at 1.36% SOC. Andosols have a tendency to accumulate C overtime

(Arnalds, 2004), however Leblans et al. (2017) has hypothesized that increasing C sinks of

Icelandic grasslands could be alleviated by mitigating N limitation by increasing anthropogenic N inputs. Vilmundardóttir et al. (2014) presented similar results, showing initial low TN which accumulates over time, and SOC values increasing from 0.05% to 1.77% SOC after 120 years of soil development. Crittenden (1975) has investigated N2-fixation on the glacier foreland of

Sólheimajökull, Iceland, concluding that lichens are probably the major contributors to the fixation in the chronosequence. The amount of SOC and N in the soil are important to microbial interactions, plant growth, aggregate formation, and other properties. Chemical weathering of silicate minerals is another mechanism of C sequestration, especially in volcanic rocks with rapid weathering rates (Lal, 2009).

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Analyzing the available forms of N in the moraines, demonstrated that there is relatively low N overall as well as in available forms. The moraines nitrate and nitrite levels were below the

LOD, and thus are not able to be interpreted. Furthermore, there was detectable amounts of

-1 ammonium ranging from 0.53 to 2.16 mg NH4-N kg soil in the 1930 moraine. The concentrations in the oldest moraines were significantly less than the reference area, which

-1 exhibited 38.6 mg NH4-N kg soil in the 0 – 5 cm depth. Brenner (2016) observed a similar trend in Icelandic soils, using the same N-species determination method, with detectable ammonium and unknown nitrite and nitrate values. The average concentration of ammonium shows a slow trend of accumulation with increasing chronosequence age at Breiðamerkurjökull.

Nutrient availability is important to the soil productivity and microbial interactions in soil solution. The availability of nutrients showed significant changes in the chronosequence of moraines for all of the following ions: Al, Ca, Cu, Fe, K, Mg, Mn, Na, P, S and Zn (Table 2.5).

However, there is a lack of literature pertaining to nutrient availability in Icelandic soils to draw comparisons. When assessing the plant available nutrients of an Andosol, the mineralogical composition is divided into two groups, allophanic and non-allophanic (Shoji et al., 1993). The mineral composition of tephra can vary widely according to the rock type, thus can affect the availability of these nutrients. P, K, Ca, Mg, and S are among the macroelements needed by plants and microorganisms in the soil. P is a component of nucleo- and other proteins and of many enzymes; it is involved in phosphorylation and energy transfer (Jenny, 1980).

Potassium (K) is an important nutrient in soils, by enhancing swelling, plays a role in translocations of organic molecules, and operates in the stomatal opening of leaves (Jenny, 1980).

In freshly deposited tephras, K is present in considerable amounts, however is often insufficient for continuous cropping (Shoji et al., 1993). K, Ca and Mg are important due to their requirement in large quantities. However the availability of elemental concentration ions is the important for

107 plant and microbial organisms. The ease with which the essential elements are rendered soluble depends upon the complexity of the soil minerals and on the intensity of weathering (Brady,

1974).

There are few studies that specifically address the availability of nutrients by Mehlich III extraction, and this is typically applied to agricultural soils (Michaelson et al., 1987). The

Breiðamerkurjökull moraines provide a unique record of observations demonstrating the change in concentration with time.

3.3 Trends across the bird hummocks chronosequence

Evidence of the seabirds utilizing the Breiðamerkursandur as an area for breeding and nesting, results in the formation of hummocks created by the accumulation of droppings where birds regularly perch and defecate (Vilmundardóttir et al., 2015). Birds that forage at sea and breed on land deposit large amounts of waste, eggshells, feathers and carcasses near their colonies. When visiting the hummocks sampling sites, observations of artifacts found at the site were recorded for the site description, and photographed as seen in the 1890 hummock (Figure

3.2). The quantity of biogenic nutrients deposited by seabirds on soils depends on their daily rate of excrement production, which is a function of the colony size, the length of time birds remain in a colony, the bird species, and their body size (Zwolicki et al., 2013). However, this study was unable to quantify the amounts of inputs by birds annually, or across at various ages of the 127- year chronosequence.

The effects of seabird droppings on the moraines created a stark difference in the vegetation and soils between the hummocks and the surrounding nutrient poor moraines

(Vilmundardóttir et al., 2015). Sigurdsson and Magnusson (2010) conducted a study at the island of Surtsey of the southern coast of Iceland, and determined the initial steps of such development

108 can be much faster than previously expected due to the nutrient transfer of seagulls from sea to land. This is evident with soil profiles of hummocks, where horizonation is evident (Figure 3.3).

The hummocks were sampled at two depths (0 – 5 cm, 5 – 15 cm), and using ANOVA analysis the age-groups were compared for significant differences between the age-groups. The top depth of the hummocks showed significant differences for pHNaF, P-retention, available ammonium, available ions Mg, P, Al, B, Cu, Fe, Mn, and Na. However, there was not a significant difference between the age-groups for pH (H2O), SOC, TN, available ion Ca, K, Mo,

S, and Zn. The lower depth (5 – 15 cm) of hummocks showed significant differences for pHNaF,

P-retention, SOC, ammonium, available ions K, Al, B, Cu, Fe, Mn, Na and S. There were not significant differences between the age-groups for pH (H2O), TN, available ions Ca, Mg, and P.

Figure 3.2 Images from Breiðamerkurjökull hummocks, eggshells (left) were documented at the 1890 site, and feathers (right) observed at the 1982 site (Turner, 2017).

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The hummocks did not show the same trend for pH (H2O) over the chronosequence, and were not significantly different at any age-group, values ranged between 5.7 – 5.9 pH. The soil in the hummocks seem to be reaching the acidic pH levels sooner than in the moraines samples, potentially due to the increased organic acids from the seabirds. Birds that forage at sea and breed on land deposit large amounts organic materials near their nests (Fig. 3.2), which facilitates the soil development by providing nutrients (Zwolicki et al., 2013). Analysis of waste has shown that bird’s wastes tend to be richer in essential plant nutrients than is that of mammals, because birds add a large quantity of material from other sources including, feathers, pellets, fins, shells and plant remains (Gillham, 1956). Increased concentrations of organic acids could affect the weathering of the tephric materials and lead to soil with a low pH faster than the materials without the inputs from bird activity, as well as stability (e.g. Zwolicki et al., 2015; Arnalds,

2008).

Figure 3.3 Image of the 1982 hummock profile sampled at Breiðamerkurjökull (Turner, 2017). 110

When high pHNaF values are found, this can be concluded as soils derived from volcanic materials and ash. The hummocks at 0 – 5 cm measured pHNaF values ranging from 8.5 to 9.1, and for the 5 – 15 depth ranging 9.1 to 10.0 (Table 2.7). The trends are similar across the chronosequence with only one group significantly different for both depths. This is interesting that both pH (H2O) and pHNaF appear to be stabilizing in the hummocks. Vilmundardóttir et al.

(2014) is among the few studies to have measured pHNaF of soils across a chronosequence, and to evaluate how they develop over time. The increasing pHNaF values over the first 82 yrs of the chronosequence could be an indication on the formation of allophane within the soil profile.

(Vilmundardóttir et al., 2015).

There is a significant difference between the development of the P-retention in moraines and in the hummocks. There was a lack of investigations over a chronosequence showing how this P-retention changes in Andosols in the early stage of development. Since phosphate sorption is a function of soil pH, the acid pH values increase the amount of P-retained (Shoji et al., 1993), and could be a factor in the increased retention of P in the hummocks, with the acid pH (H2O).

The hummocks P-retention at both depths showed significant differences between the age-groups. The top depth initially retains 14.5% P and increases to 48.9% P at the 1890 hummocks. The lower depth initially retained 14.3% P and increases to a maximum of 40% P in the oldest hummocks. The P-retention and pH (H2O) value of the soils were statistically influenced by the seabird presence (Zwolicki et al., 2013). The higher concentration of organic acids from the birds could potentially be changing the length of time for the moraines potential to retain P. Zwolicki et al. (2013) concluded that increased inputs from seabird colonies

- + - significantly enhanced soil conductivity, nitrogen (NO3 , NH4 ), potassium (K ), and phosphate

3- (PO4 ) ion concentrations and led to reduced pH values. When the seabirds increase the availability of P this may contribute overcoming nutrient limitations for microorganisms and

111 plants establishing in these early soils. Borkowska et al., (2015) observed a rise in phosphorus content at the nesting sites of Corvus frugilegus as opposed to the control sites in poor nutrient habitats. Generally, the moraine soils do not retain as much P as the hummocks do. Under the influence of seabirds, potentially the hummock soils are developing towards Andic properties more quickly.

Crocker and Major (1955) demonstrated a similar trend of increasing SOC for the initial

150 years, and steadies by 200 years terrain age. Freely drained areas of Andosols in Iceland, also the conditions for our sampling site, commonly observe up to 6% C in horizons not disturbed by land use (Arnalds, 2008). The Breiðamerkurjökull hummocks demonstrated greater amounts of C in the soil than the moraines, thus documenting the impact of seabirds on the chemical and physical parameters of the Arctic soil (Zwolicki et al., 2013).

Available ammonium in the hummocks is greater than the amounts exhibited in

-1 moraines. The top depth ranged from 0.9 to 19.1 mg NH4-N kg soil, and the bottom depth

-1 ranged from 0.17 to 4.6 mg NH4-N kg soil (Table 2.9). However, the available nitrate and nitrite were predominately below the LOD, as seen in the moraines, however there were a few hummocks with detectable concentrations. Leblans et al., (2017) found that enhanced N availability—either from accumulation over time, or seabird derived—increased the net SOC storage rate in the soils of three islands of the Vestmannaeyjar archipelago, south Iceland.

However, seabird-derived N inputs have as main disadvantage that they differ from the typical anthropogenic N deposition because N is in organic form (Schmidt et al., 2004) and because bird excrements also contain other nutrients depending on their specific diets (Zwolicki et a., 2013).

The N supplied by seabird colonies exerts an important effect on development of Arctic plant communities and the appearance of new plant taxa (Otero et al., 2018). Vevers (1936) acknowledged the effect of the seabirds in localized habitats, and the important effect of flora on

112 an island because the seeds have been mostly transported by birds as well as inputs of guano. The study at King George Island (Zwolicki et al., 2015) observed higher concentrations of N ions in

- the colony affected sites than the control sites, as well as showing NO2 as the lowest concentration of available forms. The various bird species nesting in the Breiðamerkurjökull glacial fore-field could have numerous potential diets, thus the different species will have different levels of impact on the soil’s chemical and physical properties. Further chemical analysis of excrements from the birds at this site could provide beneficial information about the rate of application from birds to the soil, as well as how they influence the nutrient availability.

The hummocks (at both depths) showed a significant difference in concentration from the moraines in the Ca, K, Mg and P nutrients, but not the concentrations of S (Table 2.5). The concentration of macro-nutrients in the hummocks observed a wide spread of averages across the chronosequence (Figure 2.10). The hummocks appear to follow a similar trend to the moraines, showing a weak trend of increasing K, Mg, S and P (Table 2.6). The seabird’s inputs are demonstrating a significant difference in the concentrations across the chronosequence from the moraines.

The hummocks demonstrated changes of nutrients over time for the following nutrients,

Al, B, Cu, Fe, Mg, Mn, Na, and P (Table 2.5). The concentrations of Mo and Zn were not significant over time for the hummocks at both depths, and many sites did not have a concentration greater than the LOD and were negligible. The crucial role of seabirds in the enrichment of nutrient-poor polar terrestrial ecosystem is well-known (Vevers, 1936) and can influence the various soil parameters, such as concentration of ammonium, nitrate, phosphate, Mg and K ions, as well as soil humidity, conductivity, and respiration rate (Zwolicki et al., 2013).

The results of this research provide evidence that the bird mounds are developing more quickly than the moraines, but with added organic inputs alone cannot be the only factor

113 contributing to the rapid development. Before human settlement in the late-ninth century A.D., the landscapes of Iceland were more resilient to natural processes, and where major anthropogenic modifications of ecology drove geomorphological change (Dugmore et al., 2009).

Areas of degradation are often prompted by overgrazing and leaves breaks in vegetative cover causing severe soil erosion (Gísladóttir, 2001). The hummocks are distinguished from the moraines by their thick grasses, herbs and moss; vegetative cover is an important element in collecting wind-blown materials.

Icelandic soils and geomorphic surfaces can be divided into two main categories: land with vegetation and barren land or deserts (Arnalds, 2010); with soils under vegetation indicating clear andic properties. There is also a lack of cohesive clay minerals in Icelandic soils, which contributes to the high wind erosion susceptibility of the sandy surfaces (Arnalds et al., 2001).

The hummocks at Breiðamerkurjökull provide evidence of accumulation of material both from weathering of substrate as well as from deposition from wind and water erosion. The bird hummocks show well developed soil even on earliest moraines sampled, and generally very little time change subsequently. The outwash plain moraines will likely be experiencing an extended lag time until vegetative cover is established, stabilizing the materials.

3.4 Comparing the moraines and hummocks

It is often assumed that much of the Aeolian material deposited in Iceland are Brown

Andosols being transported and re-deposited because of wind erosion, thus the material originates from degraded areas which are more susceptible to wind erosion (Arnalds, 2010). The chronosequences for the moraines and hummocks provide evidence that the soils are forming differently. Potentially moraines are forming from deposition of parent materials by the glacial retreat and tephra deposits, but without vegetative cover the weathered fine materials are washed

114 or blown away. The hummocks are establishing vegetative cover more quickly, potentially due to birds assisting in seed dispersal (Vilmundardóttir et al., 2015), and results in an environment that accumulates the wind-blown materials. The reference site included a tephra deposit from the

Grímsvötn 2011 eruption, as well as the hummock sampled at 1994, 1960, 1945 and 1890

(Vilmundardóttir et al., 2015). However there was no evidence of the tephra deposited in the moraines sampled. Arnalds (2010) exhibited that aeolian depositon rates of materials in Iceland can range from 13-26 g m-2 yr -1 (low rating) to 569 – 807 g m-2 yr-1 (very high).

If the hummocks are developing under different soil forming factors, the chronosequences become more difficult to interpret and compare (Walker et al., 2010). The hummocks are already more-developed or mature soils compared to the moraine sites, but shares similarities with the birch woodland reference site. From comparing the results, the moraines and hummocks could be interpreted as separate chronosequences, due to the time and parent materials. The moraines are developing towards the same andic properties, but it is taking a considerably different amount of time to reach the same concentrations seen in the hummocks.

Material weathering in the moraines are likely to be lost from the profile and deposited at another site, or collected by the vegetation of the nearby hummocks. The rates of erosion and build-up at these sites would be beneficial to understanding the mechanisms in which these soils are developing.

Vilmundardóttir et al. (2015) presented that the vegetation of the Breiðamerkurjökull foreland is dominated by mosses along with lichens, biological crust and grasses; when vegetation was present the soil was more effective at accumulating OM, SOC and TN. Using the chemical analysis, there is evidence for the difference between the chronosequences. Many variables are significantly different across the moraines, showing changes with different stages of

115 time. However, properties exhibited in the hummocks were more stable across the age-groups and indicated more development to andic properties.

3.5 Limitations of study and areas of further investigation

There are a few limitations of this study, which could be examined further for future research. Specific information pertaining to how much is accumulating and how much is weathering in these sites, moraines, hummocks, and the reference area. The rate of accumulation and deposition depend on multiple factors including: grain size, distance from Aeolian sources, topography, drainage and vegetation. Wind erosion in Iceland is an important factor for the soil environment (Arnalds and Kimble, 2001).

Another limitation of this study would be sampling; there is a need for more intense sampling across the outwash plain and at different times of year. Nutrient availability can be variable for different seasons, temperatures and water availability in the soil. Chronosequences are well suited for measuring plant and soil characteristics that change in a relatively predictive, linear fashion (Walker et al., 2010). However this thesis provided evidence that there may be issues comparing the moraines to the hummocks, due to a potential variation in time and parent material.

Filling the knowledge gaps by focused research would provide soil scientists with a better understanding of these developing soils under the impacts of climate change. There are few studies done on the development trends in postglacial fore-fields of Iceland, especially with analysis of chemical properties, and nutrient availability.

Considering the limitations for this study brings forth more questions about the properties of the moraine soils and the hummocks. The main question is how are these soils developing, and are they developing under different processes. Soils are the product of a complex suite of

116 chemical, biological, and physical processes. Thus, further investigation into these properties, as well as, mineralogy, and spatial analysis could potentially answer these questions.

The chemical analyses at this study site could be expanded to more methods relevant to other studies conducted on volcanic soils. Mehlich III is used in this study, but Bray-1 and the

Olsen test are also used (Sawyer and Mallarino, 1999; Arnalds, 2010; Gudmundsson et al., 2014).

Due to the variable charge in volcanic soils analyzing CEC using the Gillman and Hallman approach (1988) would provide beneficial information about chemical reactions. Ammonium oxalate extraction obtained by Blakemore et al. (1987), is commonly used in volcanic soils

(Vilmundardóttir et al., 2014) and could provide useful comparisons to other studies. Mineralogy of volcanic soils is important to weathering rates and soil properties, and can reflect the composition of the bedrock in the glacial forefield (Bernasconi et al., 2011). Weathering rates of young soils can be on different orders of magnitude higher than mature soils. Thus X-ray diffraction would be a beneficial analysis of clay mineral formation across the chronosequence, and transformations within a relatively short period of time (Mavris et al., 2011).

Physical properties are difficult to analyze in these soils due to the high gravel content

(Stanich, 2013). However, the aggregation and development of structure in these soils is informative about the soil forming factors. Soil structure plays a dominant role in the physical protection of soil organic matter by controlling microbial access to substrates, turnover and food web interactions (Jastrow and Miller, 1997). Thus, information on the dynamics of organomineral associations will lead to a greater understanding of structural changes, turnover time, and C sequestration in soils. Porosity and water measurements (i.e. water content, water potential and water stress) could provide fundamental information about the interactions of microorganism and plant roots in the soil.

117

The formation of soil is well-studied overall from a chemical and physical perspective

(Matthews, 1992), but much less from the biological perspective. Analyzing soil development from an ecosystem perspective during soil formation along a retreating glacier presents a more comprehensive view of how the soil is changing. A glacial chronosequence study could include analysis of food web development, vegetation succession and soil ecological processes (van

Leeuwen et al., in review). The understanding of biogeochemical processes at the interface between geosphere, hydrosphere and biosphere is of paramount importance for many questions related to global climate and environmental change at very different time and spatial scales

(Bernasconi et al., 2011).

Spatial variability characterization of soil properties is essential to understand soil behavior and its relationship with environmental factors (Valle et al., 2014). Thus, modeling and mapping may provide useful predictions and trends for analyzing the spatial distribution of the soil development. Soil on the landscape is a body of nature with internal organization with a history of genesis and it’s alive, thus there are changes (Jenny, 1980). The Breiðamerkurjökull soils could be mapped on a smaller scale than the current available soil maps, such as the coarse grained (1:250,000) map (Arnalds, 2008). Spatial variability is the result of soil forming processes and factors (Jenny, 1941) and, soil management, in addition to the interaction of these drivers across space and time. The differences of chemical characteristics determine the management and use of these soils.

Additionally, further analysis on the composition of inputs directly from the seabirds, as well as data collected on the number of birds utilizing the study site. Magnusdottir et al., (2012) showed that individual Great Skuas often return to the same region in successive winters. The locations, distribution of the nests on the landscape, and frequency of use by breeding pairs could also be analyzed at the study site Breiðamerkursandur. There are many factors of birds

118 excrements are also unknown including: chemical composition of waste, diet of specific birds, concentration of the birds in the regions, as well as, the frequency of use at bird hummocks.

3.6 Final statements

The soils of recently de-glaciated terrain and their development are complex, due to the physical environment characterized by variability at different spatial scales (Matthews, 1992).

The changes in soil chemical properties over time are an important component for understanding the soil development. Icelandic soils have undergone large scale erosion, and as a result the SOC, nitrogen (N), and other nutrient pools of eroded surfaces differ greatly from those under vegetated land (Gísladóttir et al., 2010). The degradation and desertification of soils in Iceland are depleted of the SOC, and there is a strong interest in restoring these soils and ecosystems in order to sequester C (Lal, 2009). Present day restoration efforts are also focused upon a variety of goals including, increasing the diversity of species and habitats, strengthening the resilience of ecosystems that are prone to volcanic deposition or glacial flooding, and continuing to stabilize encroaching sand (Arnalds, 2004; Aradóttir et al., 2013).

This study analyzed a series of chemical properties in the soil including: pH, P-retention, total SOC, TN, available N-species, and biologically available Mehlich-III nutrients. Then analyzed each properties trend across the chronosequence at Breiðamerkurjökull. The measured soil properties showed changes across the chronosequence in all of the following, pH (H2O), pH

(NaF), P-retention, total SOC, available ammonium, Al, B, Cu, Fe, K, Mg, Mn, Na, S, and Zn.

There was not a significant change in values in TN, available Ca, Mo, and P, when combining data over the moraines and hummocks.

In conclusion, the moraines of Breiðamerkurjökull, demonstrated development of chemical properties seem to evolve in direction of andic properties. There was a different trend of development for most properties in the hummocks when compared to the moraines across the

119 chronosequence. In some cases, seabird colonies have profoundly altered the biogeochemical processes that occur in coastal surface systems (soils, sediments, and waters), and have transformed plant communities (Otero et al., 2018). The importance of seabirds impact on the environment has been acknowledged for a long time (Vevers, 1936), but has been increasingly acknowledged in recent years (i.e. Leblans et al., 2017; Vilmundardóttir et al., 2015; Zwolicki et al., 2013; 2015). In areas of the world where colonies are found, the birds are vitally important to the function of the ecosystem structure, seed dispersal and nutrient transport from sea to land

(Sigurdsson and Magnusson, 2010). The Breiðamerkurjökull chronosequence demonstrates a unique case study of various chemical and nutrient properties of the glacial moraines and how they change over time.

3.7 References

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Appendix: Abbreviations

LIA: The Little Ice Age OM: Organic Matter SOM: Soil Organic Matter SOC: Soil Organic Carbon C: Carbon N: Nitrogen TN: Total Nitrogen + NH4 : Ammonium - NO3 : Nitrate - NO2 : Nitrite CEC: Cation Exchange Capacity Al: Aluminum B: Boron Ca: Calcium Cu: Copper Fe: Iron K: Potassium Mg: Magnesium Mn: Manganese Mo: Molybdenum Na: Sodium P: Phosphorus S: Sulfur Zn: Zinc NaF: Sodium fluoride solution ANOVA: Analysis of Variance

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