Landscape Indicators: Assessing and Monitoring Landscape Quality

The journal provides a forum for the discussion of the applied scientific development and review of traditional indicator applications as well The journal provides a forum for the discussion of the applied scientific development and review of traditional indicator applications as well as for theoretical, modelling and quantitative approaches such as index development. Research into the following areas will be published. The journal seeks innovative papers which provide new developmental and methodological steps for environmental indication. Submissions of results from simple monitoring programs or single case studies, resulting in descriptive approaches without any exploration from the theory of indication, from the methodology of indication, or from the management points of view are not considered suitable for publication in Ecological Indicators.

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Order Journal Institutional subscription Personal subscription. CiteScore values are based on citation counts in a given year e. View More on Journal Insights. Publishing your article with us has many benefits, such as having access to a personal dashboard: This free service is available to anyone who has published and whose publication is in Scopus. Researcher Academy Author Services Try out personalized alert features. The following contributions will be accepted: Annukka Lehikoinen Laura Uusitalo Identifying landscape species for ecological planning Mahmoud-Reza Hemami.

Zhongguan Jiang Lizhi Zhou Heavy metal pollution in surface water and sediment: Comparison of characteristics of geodatasets from the US and Canada used in this research. Approach for improving concordance among these datasets is explained further in the text Landscape indicators and additional co-variates were calculated within concentric zones of influence , m surrounding each groundwater monitoring well.

Models in bold represent best model for that response variable based on Adj. R2 and AIC values. Comparison of models for assessing nitrate concentrations on the USA-side of aquifer using indicators measured within m and m, circular and Semi-circular shaped zones of influence. Models in bold represent best model for that response variable variable based on Adj. Comparison of characteristics of geospatial datasets used in this research.

Concordance of datasets is explained further in Chapter 3. Landscape indicators calculated within the m wedge-shaped zone of influence surrounding each groundwater monitoring station using the geodata described in Table 1. To consider the age of water collected at various well depths, mean depth of mid-screen was included in each model. The best model for each response variable is shown in bold.

The extent of global agricultural land during the s. Foley et al Science ; Since the creation of the Haber - Bosch process, synthetic nitrogen use has seen a four-fold increase Millennium Ecosystem Assessment, The map shows aggregated data per country, classified from none, few and many zones where high concentration of nitrate have been reported. Based on a literature review, the map demonstrates the percentage of regions with high nitrate contamination in the world.

Elevated nitrate concentrations have plagued the aquifer in recent decades. This thesis sets out to study linkages between LULC and groundwater using landscape ecological approaches over two spatial extents: Using harmonized land use and land cover data explained in Table 2. Percentage of land cover types for each city in and This represents land cover within 10 km radius of the city center Changes in percent or landscape PLAND of land cover classes along the rural to urban gradient km, km, km, km, km radius.

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Most cities experience peak evenness km from the city center. The Abbotsford-Sumas study region located in southwestern British Columbia and northern Washington is a km2 unconfined, highly permeable sand and gravel aquifer recharged primarily by direct precipitation. Modified from a map originally from: Semi-circular shaped zones from m and m surrounding each well were created to incorporate the southwesterly groundwater flow direction.

The Abbottsford-Sumas Aquifer ASA in southwestern British Columbia and northern Washington is a km2 unconfined, highly permeable sand and gravel aquifer recharged primarily by direct precipitation. The aquifer has been the subject of longstanding nutrient management challenges affecting both countries. Groundwater monitoring stations in the ASA. A total of 22 wells were analyzed over time , while a subset of 14 wells were used to link land cover to nitrate concentrations.

Thank you for allowing me to enjoy my time at UBC on your traditional, ancestral, and unceded territory. To my committee members, Lael, Hans, Sean, and Gwyn: Thank you for your feedback and guidance through this PhD process. I look forward to many years of collaboration in the future! To my friends and family: Thank you for your encouragement and for enduring my lengthy FaceTime calls these past five years.

Those chats mean the world to me as you often provided me with a smile just when I needed it most. To each and every one of my roommates: Thank you for enduring my late night writing sessions and guitar playing and for making our lovely little house on Mackenzie Street a place of retreat. I really hit the roommate jack pot time and time again. You helped make our house a home and paved the way for more wonderful roommates even after your departure to California. Thank you both for your love and encouragement and understanding through this entire degree. To my lab mates: Thank you for your support through this.

You made going in to the lab a true pleasure. To Karly and Kevin: That was brilliant and precisely the dose of sunshine that I needed!! I knew from my first meeting with you that I wanted to be your student and I have enjoyed every second of it. I look forward to many future visits and projects together! My journey to Vancouver and the start of this project began just a few days after you were born.

Watching you grow into the beautiful, thoughtful, and inquisitive child you are, has been a continual reminder of the importance of fostering a sustainable and resilient future. As a result, land use and land cover LULC change has become a force of global importance Foley et al , Vitousek et al Agricultural conversion of natural lands is acknowledged as one of the greatest anthropogenic impacts to the environment globally Ramankutty and Foley , Matson et al Agricultural expansion as well as agricultural intensification via use of fertilizer, irrigation, and high yield crop varieties has greatly increased food production over the last 50 years Naylor However, despite such improvements in food production, the long-term sustainability and environmental consequences of agricultural systems are of great concern.

Altered flux of nutrients - such as nitrogen and phosphorus - are a large part of this dilemma Howarth et al , Johnson et al Foley et al, Science ; The creation of reactive nitrogen N via the Haber-Bosch process in the early s prompted the Green Revolution. While the Haber-Bosch process has helped increase global food production, the increase in global reactive nitrogen has also taken an unforeseen toll on ecosystems and has fundamentally impacted the way humans practice agriculture Sebilo et al , Kaushal et al , Fields Since the invention of synthetic fertilizers, the number of people supported per hectare of arable land increased from 1.

Together with new high yielding, short-stalked varieties and chemical protection, yields of wheat and rice worldwide tripled and quadrupled during the 20th century opening the door for farms to move away from the millennia-old system of cycling and re-cycling nutrients and organic matter in each farm Smil The resulting manure from cattle and poultry, etc. This disconnect between animal husbandry and row crop agriculture disrupted previously more localized flux and re-use of nitrogen, creating a two-fold problem: Globally, livestock has increased in the last 50 years with the number of cattle increasing from million in to 1.

Production of pork and poultry has also increased from million and 2. Once a highly valued resource, animal manure has become a waste disposal problem Pollan , Montgomery , Hager This increase in application of industrial N along with the surplus of manure N has helped create several ecological problems including surface water eutrophication and groundwater contamination Rabalais , Wu and Sun As global landscapes transition to more intensive agriculture and urbanization, groundwater is increasingly susceptible as land use and land cover LULC 5 change can have significant repercussion on recharge rates and quality Eckhardt and Stackleberg , Loague and Corwin , Kolpin Adverse effects may also be possible below WHO guidelines, however, as long-term exposure to nitrate- in community water supplies as low as 2 - 4 mg NO3- - N L-1 has shown possible links to bladder and ovarian cancer Weyer et al Land use patterns, including historical, current, and future anticipated changes in land use, are part of this challenge.

The impacts of LULC change on atmospheric components of the hydrologic cycle regional and global climate are well-recognized Bonan, ; Pielke et al ; Pitman et al. For example, land cover changes have been linked to altering albedo, increasing regional temperatures and reducing precipitation Pitman et al , Cao Though the impacts of LULC on atmospheric components of the hydrologic have been explored, fewer studies examine the impacts of LULC change on subsurface components of the hydrologic cycle Scanlon et al These impacts are multifaceted, linked not only to agricultural expansion but also to the loss of agriculture to urban expansion, both of which impact nitrogen flux to surface and groundwater.

One approach to understanding how LULC influences groundwater is through landscape indicators which can be easily created using GIS and remote sensing. Landscape indicators quantify the amount and arrangement of land cover such as percent agriculture and percent forest cover and characterize the physical structure of vegetation on the land surface Meyer and 7 Turner They allow for an affordable, broad-brush approach to characterizing the landscape and identifying potential LULC impacts.

A long-standing, well-developed body of research examines the correlations between landscape indicators and surficial aquatic ecosystems Gergel et al , Allan , Johnson and Host As such, the potential mechanisms shaping the correlations between LULC and water quality are well understood in a qualitative sense. Nonetheless, the strength of quantitative predictions can vary greatly depending upon the landscape indicator used and the region over which it is applied.

While a plethora of research has examined landscape indicators relative to surface waters Hale et al , Mallin et al , few have examined landscape indicators within the context of groundwater aquifer monitoring Gurdak and Qi , Keeler and Polasky , despite the links between surface and groundwater systems. Furthermore, much of the landscape indicators research is highly correlational - using only land cover-based indicators - and is generally lacking in a deeper exploration of mechanisms associated with land use practices.

To help fill these knowledge gaps, I seek to identify fine-scale landscape indicators that better account for land use practices likely related to nitrate loading. My work helps improve the development of landscape indicators for groundwater by identifying and better incorporating potential mechanisms and processes acting above and below the land surface Sophocleous My overall objective is to develop approaches for 8 examining LULC impacts to groundwater systems. I accomplish this in two main parts: The ASA, which spans Northwestern Washington state and Southwestern British Columbia, has a long history of persistent elevated nitrate concentrations.

The many complexities of this problem have challenged managers, farmers, and policy makers in both countries who have initiated a wide variety of nutrient management strategies - with little apparent success - in reducing nitrate-concentrations. In my work, I address two nested scales: The Greater ASA region is an ideal study location for several reasons. First, many of its cities and municipalities are heavily dependent on aquifers as their primary drinking source. Second, both agricultural expansion and urbanization are occurring simultaneously throughout the Greater ASA and these LULC changes are transforming the social-ecological landscape and impacting linked surface-groundwater systems.

Thirdly, these trans-boundary aquifers are influenced by policies and economic drivers of two countries. Thus, my cross-border approach enables comparative research relevant to both countries. Through such comparisons, I determine how landscape patterns differ between the two countries and determine whether past and 10 potential future LULC impacts on groundwater might also differ.

Lastly, the ASA in particular has a consistent, very well-developed long-term groundwater monitoring program, along with an abundance of historical imagery. Integrating this extensive and somewhat unique suite of long-term data can help shed new light on groundwater issues in this particular region yet also provide a valuable adaptable approach for monitoring in other cross-border aquifers where LULC is of concern.

This thesis is comprised of three research components linking groundwater and land cover change. To provide broad context for landscape changes occurring throughout the region, in Chapter 2 I explore where, and at what rate, land conversions are taking place via a trans-border regional LULC change analysis of the Greater ASA region. Next, I discuss the overall goals and original contributions of each chapter.

Trans-border monitoring of landscape pattern Monitoring transboundary aquifer bodies is complicated by the complexities associated with multi-jurisdictional governance, disparities in data collection, and inconsistencies in geospatial data among countries. To broaden our understanding of the spatiotemporal landscape footprint of agricultural expansion and intensification, which is often followed by urbanization, I quantify changes in LULC patterns for cities where groundwater is an important source of drinking water.

Using a myriad of geospatial data sources and landscape analysis, I seek to answer: I identify how landscape patterns change over time along the urban-rural gradient of these cities as they expand into the suburban fringe and surrounding agricultural areas. The over-arching theme of this chapter is to quantify spatial and temporal trends in landscape patterns and to discuss their potential implications for groundwater water quality.

This work also helps provides broad regional context for Chapters 3 and 4. Are there linkages between contemporary nitrate concentrations and contemporary land cover? After characterizing landscape change throughout the broader region, next, I narrow in on how LULC impacts nitrate concentrations in a specific aquifer for which detailed monitoring data exist. I ask two questions: To accomplish this, I first test for statistical trends in nitrate concentrations over time. Second, I combine cross-border geospatial data to develop landscape indicators characterizing likely N sources and examine their correspondence with groundwater nitrate concentrations.

Through linking these contemporary landscape indicators to contemporary nitrate concentrations, I aim to help portray the current state of the aquifer. This work also provides an important transportable approach that is highly relevant to other regions facing similar management challenges and lays the foundation for understanding how to quantify potential sources of nitrogen using landscape indicators. Additionally, I seek to answer three subsidiary objectives, to determine: To do so, I calculate landscape indicators within terrestrial zones of influence composed of differently sized radii surrounding monitoring wells and account for directionality of subsurface flow.

Finally, I compare my results for the US and Canada. I hypothesize that incorporating distance and directional flow into landscape indicators will increase their predictive power and thus improve our understanding of the factors contributing to high nitrate concentrations throughout the ASA. While this chapter examines recent nitrate concentrations from and links it to land cover, in the next chapter, I look even deeper in time to link historical nitrate concentrations with historical land cover.

Are there linkages between historical nitrate and historical land cover? Historical LULC can influence water chemistry for decades. Despite its importance, very few studies have quantitatively evaluated historic land use patterns and their correspondence with groundwater nitrate concentrations. Building off the previous chapter, I evaluate even longer-term trends to assess potential lagged effects of LULC on nitrate concentrations.

I use high spatial resolution imagery to map fine-scale features such as field hedgerows and land use practices such as replanting of raspberry fields potentially linked to nitrate loading. I also incorporate groundwater flow direction to better capture areas potentially contributing to nitrate leaching.

Extending my analysis of the ASA aquifer by an additional 30 years, I ask two primary questions regarding landscape legacies: To accomplish this, I 13 examine trends in groundwater nitrate concentrations at monitoring wells across the aquifer in a similar fashion to Chapter 2, but I add new information from landscape indicators originally mapped on historical aerial imagery from the s. I hypothesize that correlations between present day nitrate concentrations and historic LULC and may be important because of lagged effects of land use practices. A look towards the future of transboundary aquifer management In my concluding chapter, I provide a summary of my key findings, discuss limitations of my approach and its significance, both locally and globally, and I explore directions for future research and community-based management.

I also posit that there are potential benefits of taking a more socio-ecological approach to groundwater monitoring whereby techniques such as future scenario planning can garner greater community involvement in decreasing nitrate concentrations over time. This synthetic and integrative research has global implications as management of oft-shared trans-border groundwater resources can result in trans-national conflicts. Transboundary Monitoring of Landscape Pattern 2. Along with transitions to more intensive agriculture, agricultural lands are being lost to urban land uses with accompanying increases in impervious surfaces across the landscape.

Such landscape transitions have become a worldwide concern Alexandratos and Bruinsma as population growth pushes cities to expand their boundaries. This urban expansion can impact previously disjointed landscapes where high density populations are concentrated in one location yet agricultural and wildlands are dispersed elsewhere.

Patterns of land conversion in outlying exurban environments are of increasing as these changes impact ecosystem services, biodiversity, and aquatic systems Johnson , Grimm et al , Han et al Land cover change surrounding smaller urban centers is particularly important as they are key locations undergoing agricultural transitions.

Land conversion across broader scales metropolitan, state, or nation-wide scales has received great attention, yet less attention has been paid to smaller cities Goldewijk , Foley et al , Keys et al Half of the US population live in rural areas or small jurisdictions under 25, people such as towns, boroughs, villages and townships Cox Such rural communities can be highly dependent on groundwater for drinking water supplies. Groundwater is particularly susceptible to LULC change as increases in impervious surfaces and loss of wetlands can have significant repercussion on recharge rates and water quality Loague and Corwin , Kolpin et al Of increasing interest to ecologists, and of longstanding interest to regional planners, is the rural-urban gradient McDonnell and Hahs , Ramachandra et al which emphasizes differences along a spatial continuum from urban to rural areas Haase and Nuissl As 15 defined, this gradient primarily extends from the urban core to rural outskirts Kroll and Kabisch Urban to rural gradients have been widely used to analyze impacts of landscape change on non-point source NPS pollution Lovett et al, , Gingrich and Diamond , water quality Wear et al, , ecosystem services, avian diversity and richness Blair , Mortberg , and invertebrate communities Walsh Despite the many studies quantifying changes in landscape patterns along urban-rural gradients, few have examined smaller cities.

Ecological studies of urban-rural gradients remain focused on larger metropolitan areas McDonnell and Picket , Luck and Wu In this chapter, I am interested in understanding LULC patterns in smaller cities reliant on aquifers for drinking water. Many of the landscapes surrounding such cities are undergoing rapid agricultural transitions. Using an approach which is designed to be transportable across jurisdictions, I quantify trends in landscape patterns from to surrounding 11 urban centers.

I ask the following questions: How do landscape patterns change over time, and throughout the urban-rural gradient? Do these patterns differ between US and Canadian cities? While very few studies have examined spatio-temporal landscape patterns of smaller urban areas, even fewer have compared cities across international borders Desender et al , Clergeau et al Studying smaller cities will yield a richer picture of urban form and function and potential impacts on groundwater Bell and Jayne Further, this general approach can be used to assess long-term landscape changes in a variety of different agricultural socio-ecological landscapes.

Within the Greater ASA region, the dominant crop consists of red raspberry with significant forage grass and pasture Zebarth, There is also a substantial amount of poultry and dairy operations. From — , the number of chickens and hens within the Canadian portion of the Fraser Valley increased from Within this same area, the human population increased by 18, and total farmland area grew from just over 56, ha to nearly 61, ha from Within this region, I chose cities dependent on groundwater as a drinking water source, including: US Census, ; Stats Canada To do so, I first assembled and harmonized geospatial data from circa and for both countries.

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Characteristics of these datasets are further explained in Table 2. To harmonize these datasets to support multi-year and cross-border comparisons, I reclassified land cover into eight categories: Cropland, Forest, Urban, Vegetation land that is not forest, wetland or crop , Water, Wetland, Other Land all other land types not mentioned , and Unclassified. Reducing the total number of classes by grouping similar land cover types improves class-level accuracy Aronoff , Olofsson For this process I manually examined every class within each data set and grouped each into the most appropriate higher-order land cover grouping.

This process was exceptionally time consuming requiring careful iterative verification of my decisions and clarification of the many detailed assumptions and technical decisions underlying these original classifications from several jurisdictions. Thus, my simplified groupings of class types are at least as accurate as 19 the classes in these original data sets, with potential for increased class-level accuracy. A more detailed description of land cover types is given in Table 2. Original data sources from Table 2.

Characterizing the Urban-Rural Gradient There are two well-established approaches for examining urban-rural gradients. One approach uses a series of concentric rings originating in the city center expanding outward to rural outskirts Kroll A second approach uses directional linear transects originating in the city center extending into rural areas Hah and McDonnell , Zhou and Wang The concept of concentric rings around city centers was first developed as a model of residential differentiation i.

Vegetation Veg Any vegetation not included in cropland, forest, and wetland classes. May include grass or some wetlands with woody vegetation, regenerating forest.

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Predominantly native grasses and other herbaceous vegetation. This category may also include some shrub land cover. Water Wa Water bodies lakes, reservoirs, rivers, streams, salt water, etc. Unclassified Un Background of raster images 21 The concentric ring approach assumes cities exhibit similar spatial patterns in all directions; however cities are not necessarily isotropic Zheng, Cities with monocentric urban expansion as opposed to cities with multiple nuclei are most suitable for examination using the concentric ring approach.

Urban areas in North America typically have a densely populated urban core surrounded by rings of diminishing landscape modification Dickinson , Forman and Gordon Nearly all cities in this study exhibited one major urban nucleus and thus reflect this basic assumptions behind the concentric ring approach. Furthermore, the geography of most of the cities in this study permits equal expansion in all directions as opposed to other places where expansion is limited in one or more direction by coastlines, mountains, or other geographical features.

Where expansion is restricted, the transect approach to examining the urban-rural gradient is more suitable so that patterns can be characterized based on direction Luck and Wu , Banzhaf et al Lastly, the transect approach would hinder an important objective of this work - to compare cities north and south of the border - as some transects would proceed into the adjacent country. Thus, for many reasons, the concentric ring approach was deemed most suitable for this research several. As such, I used the concentric ring gradient method to spatially and quantitatively describe changes in landscape patterns over time.

I used a maximum radius of 10 km as a compromise between the largest possible size that also minimized the influence of urban sprawl radiating from neighboring cities. More specifically, for larger-sized cities such as Abbotsford and Bellingham, a minimum km radii distance was 22 necessary to encircle rural areas; whereas for smaller cities i. Lynden , interference of sprawl from neighboring cities was a concern beyond a 10 km radii. Spatial Pattern Analysis I examined trends in landscape patterns over time as well across the urban-rural gradient. To do so, I selected landscape pattern metrics based on their ecological significance as well as those most commonly used in land conversion studies in order to bolster their comparative relevance.

I examined class-level pattern metrics for three distinct land cover classes urban, agriculture, and forest as well as some landscape-level pattern metrics characterizing all classes simultaneously. Like total class area, it is a measure of landscape composition important in many ecological applications. PLAND is a relative proportional measure.

Thus it is a more appropriate measure of landscape composition than class area for comparisons involving landscapes of different sizes McGarigal and Marks , and in this case, comparisons among concentric rings with different total area. SHEI is a measure of the evenness of classes, expressed such that an even distribution of area among classes results in maximum evenness. Statistical Analysis I calculated change in percentage of landscape PLAND between two time periods and within the entire 10 km radius of each city, as well as compared SHEI among five distance intervals along the rural-urban gradient km, km, km, km, km.

To evaluate trends along the urban-rural gradient, I conducted a Mann-Kendall trend test of PLAND for urban, agriculture, and forest classes separately across all five distance classes. To do this, I first plotted the spatial trend for each of the three land cover classes for each city for and I then compared and results to determine how land cover trend changed over time for each city.

Changes in land cover along the urban-rural gradient over this time period for all cities are plotted in Figure 2. Because the greatest percentage changes in land cover were seen for urban, agriculture, and forest classes, these results focus on these three land cover classes. This represents land cover within 10 km radius of the city center. Additional information can be found in Appendix Table 1. Additional information can be found in Appendix Table 2.

Agriculture was the most abundant land cover type for the remaining cities of Abbotsford, Lynden and Mount Vernon.

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Urban land cover increased over time in nearly all cities with the exception of Hope, which saw a loss in urban land. Agricultural land declined in nine of the eleven cities, increased in one Abbotsford , and did not change in one the city of Hope. Urban land peaked within a km radius from the center of most cities. In , forest increased with distance from city center in five cities Abbotsford, Chilliwack, and Hope: By , forest increased with distance from city center in seven cities Chilliwack: Over time, proportional loss of agricultural lands was greater in US than in Canadian cities Dominant trends in the Canadian versus USA cities were different over time.

Urban land cover increased over time in all US and Canadian cities with the exception of the Canadian city of Hope. All US cities and half of the Canadian cities showed increases over time in urban land in all distance classes. The only cities losing urban land at any distance were the Canadian cities of Kent, Hope, and Abbotsford. All US and Canadian cities demonstrated an overall loss in forest and the greatest relative decrease in forest cover occurred in the US cities of Bellingham, Anacortes, and Mount Vernon and the Canadian city of Langley.

SHEI increased in all cities from Figure 2. SHEI increased in all cities from From to , land cover in all cities increased in evenness Figure 2. For the cities of Abbotsford, Bellingham, and Langley, evenness increased with distance from the city center. The opposite was true for Hope, which approached zero with distance from city center. Seven of the eleven cities experienced peak evenness km from the city center.

Governing bodies and stakeholders may have differing — and sometimes conflicting - agendas. Determining where and how government agencies are working together and identifying areas where cross-border management strategies and policies vary is the first step to creating holistic approaches for managing trans-boundary systems. Understanding the historical and political background of an area helps to inform land managers of which practices are most effective for maintaining a healthy and productive landscape.

An important component of this broader challenge of managing cross-border systems is mapping such areas in consistent and comparable way Pardington and Cardille, Geodata are routinely collected by a multitude of government and private agencies at differing scales, using various classification schemes, and for varying purposes. This creates many challenges concerning obtaining continuous, uniform, accurate data for a system. Landscape pattern analysis is one way to compare across regions and 31 jurisdictions, identify how landscape changes are affecting landscape patterns, and in turn, how aquatic resources might be impacted.

Landscape evenness increases as urban land increases and agricultural intensifies in the region Landscape evenness increased in all cities over the year period examined, driven primarily by gains in urban and losses in agricultural lands. Additionally, the Canadian town of Hope was the only city where urban land cover decreased. Agricultural land was lost in all cities except in Abbotsford where it increased slightly. The greatest decreases in agricultural land occurred in the five US cities. While agricultural land decreased over time surrounding most cities, according to the farm census, total production remained the same or increased, indicating the agricultural activities may be intensifying on remaining agricultural lands USDA , Ministry of Agriculture Land use policies zoning, master plans, growth boundaries help to determine urban form and its impact.

For example, in the greater Seattle area, growth management efforts to increase housing densities within growth boundaries has had unintended consequences, encouraging low density housing sprawl in rural and wildland areas just beyond those planned growth boundaries Robinson et al Land parcels falling within the ALR are limited to farm uses according to Agricultural Commissions bylaws. The ALR likely prevents or at least slows the rate of agricultural conversion to urban in the Canadian portion of the study area. As such, understanding how policies impact landscape patterns and identifying where landscape changes are occurring can help to better focus planning efforts to reduce negative consequences of LULC change on aquatic ecosystems.

Identifying changes in landscape pattern helps focus land planning to improve water quality Landscape patterns serve as useful indicators of overall water quality. The percentage of land in forest and non-forest cover as well as the density of paved roads are among the strongest predictors of overall water quality Wu and Sun , Hunsaker and Levine , Swank and Bolstad Additionally, strong links between land cover and water quality changes associated with major storm events suggests that even small changes in land cover have important implications for water quality Swank and Bolstad , Larson and Grimm , Janke et al The spatial organization of land cover, measured by contagion and dominance, may also have a bearing on water quality Hunsaker and Levine , Moreno-Mateos, , Kelting et al Hence, spatiotemporal changes in landscapes may therefore have important implications for water quality.

Groundwater is an important source of drinking water for the eleven cities in this study. Furthermore these aquifers are shallow, unconfined aquifers highly vulnerable to contamination. As such, understanding patterns of development and land conversion, and linking these changes to implications for water quality, can help planning and regulatory bodies focus efforts on critical 33 locations that may be negatively impacted by LULC.

For instance, increases in urban areas have led to an increase in food demand which has resulted in agriculture intensification within the region. This agricultural intensification has increased nitrate contamination of transboundary water sources in the region causing an international dispute over water quality. Mapping changing landscape patterns can help identify where land use is most likely to be intensified, or conversely, where it will likely remain stable or change in only trivial ways. In turn, this information can be used to create indicators of potential contamination and used in conjunction with water quality data to map and model areas vulnerable to contamination.

In a world of limited resources, such localized targeting may be as or even more effective than broad regulations intended to protect water quality Wear et al My results showed that in most cities in the Greater ASA area, urbanization is encroaching upon agricultural land use, which in turn is encroaching upon forested lands.

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Furthermore, patterns of urbanization and agricultural intensification along the urban-to-rural gradient can be well captured by landscape metrics even surrounding smaller cities undergoing major landscape transitions. I showed how landscape change is spatially heterogeneous and often occurs differentially along the urban to rural gradient. Additionally, these results provide important knowledge base for land use managers in the region. While this 34 chapter provides important background context of LULC in the Greater ASA region, the deeper implications of these changes for water quality will be further explored in subsequent chapters.

An Approach for Transboundary Aquifer Monitoring 3. Increasing use of synthetic and organic fertilizers, disposal of waste particularly from animal-based agriculture , and changes in landscape patterns are key factors responsible for the progressive increase in nitrate concentrations in groundwater over the last 30 years Townsend and Howarth Adverse effects may also be possible below WHO guidelines, however; long-term exposure to nitrate in community water supplies as low as 2 - 4 mg N L-1 has shown possible links to bladder and ovarian cancer Weyer et al Trans-boundary aquifers are particularly vulnerable to contamination.

While nearly river basins traverse international boundaries Transboundary Water Assessment Programme , twice as many aquifers span international political boundaries IGRAC Cross-border aquifers are the primary source of freshwater on almost every continent, yet the number 36 of international agreements for transboundary rivers and lakes vastly outnumber those of transboundary aquifers Eckstein and Eckstein Long water residence time, large storage capacity, physical inaccessibility for remediation, and lack of regulations make many aquifers challenging to manage, especially in cross-border settings Foster and Chilton Furthermore, the spatio-temporal scale of data collection and monitoring conducted by different countries may not be compatible nor shared among jurisdictions.

Thus, the complexity of coordinating among international agencies working across multiple jurisdictions has also likely exacerbated the long-term difficulties in addressing groundwater nitrate. Understanding how land use and land cover LULC patterns impact groundwater systems is a critical first step towards mitigating nitrate contamination.

One approach is through easily measured landscape indicators. Landscape indicators quantify the amount and arrangement of land cover such as percent agriculture and percent forest cover and the physical structure of vegetation on the land surface Meyer and Turner They allow for an affordable, broad-brush approach to characterizing the landscape and classifying potential LULC impacts. A long-standing, well-developed body of research examines the correlations between landscape indicators and aquatic ecosystems Gergel et al , Allan , Johnson and Host However, the strength of quantitative predictions can vary greatly depending upon the indicator used and the region in which it is applied.

A plethora of research has examined landscape indicators of surface waters Hale et al , Mallin et al However, despite clear connections between surface and groundwater 37 systems, few studies have examined landscape indicators within the context of monitoring groundwater and aquifers Gurdak and Qi , Keeler and Polasky Development of landscape indicators linked to land use and incorporating topography and geology can help identify and potentially explain mechanisms and processes acting above and below the land surface Sophocleous and are especially relevant to unconfined aquifers which have no overlying impervious rock layer and are therefore susceptible to contamination.

Other methods such as such as mass balance nutrient modelling can be expensive and data intensive; however, landscape indicators are a rapid and relatively affordable way to assess likely groundwater contamination. Thus, understanding landscape indicators that relate to groundwater in unconfined aquifers can improve our understanding of terrestrial groundwater interactions.

Long-term monitoring which began in the early s detected nitrate concentrations in exceedance of WHO standards Wassenaar et al , Mitchell et al Decades after being first identified, elevated nitrate concentrations have remained a persistent trans-boundary dilemma for the USA and Canada Chesnaux et al , Zebarth et al The complexities of this problem have challenged the many managers, farmers and policy makers who have initiated a wide variety of nutrient management strategies, with little apparent success in reducing nitrate concentrations in the aquifer.

Within this context, I ask two primary questions: Are there temporal trends in nitrate concentrations over time? How well do landscape indicators help explain patterns of groundwater nitrate concentrations? To accomplish this, I first tested for statistical trends in nitrate concentrations over time. I then statistically linked agriculturally-focused landscape indicators to nitrate concentrations measured in ASA monitoring wells along the US-Canada border.

Based on previous studies, I expect 38 elevated nitrate concentrations in areas with large amounts of livestock and berry production Lockhart et al , Wassenaar In addition, three subsidiary objectives were examined to determine: To do so, I calculated landscape indicators within terrestrial zones of influence for differently-sized radii surrounding each well and accounted for directionality of subsurface flow. Finally, I compared analyses of landscape indicators and groundwater nitrate concentrations collected at ASA monitoring wells across the US-Canada border.

I hypothesize that incorporating distance and directional flow into landscape indicators will increase predictive power and improve our understanding of the factors contributing to high nitrate concentrations throughout the ASA. I further foresee challenges arising from this comparative cross-border approach as geodata and monitoring techniques differ between countries. The aquifer supplies drinking water for , residents of Canada in the city of Abbotsford and the township of Langley Chesnaux et al as well as nearly 10, people in the United States towns of Sumas, Lynden, Ferndale, Everson, Nooksack, and scattered rural areas.

The unconfined, highly permeable sand and gravel aquifer is recharged primarily by direct precipitation Fraser Valley Soil Nutrient Study and consists of mostly coarse-grained sediments of glaciofluvial drift 39 origin. Such loose, or unconfined, soil strata provide minimal filtration for contaminants USGS Mean groundwater age is approximately 20 years old while models suggest a mean travel time of 6.

Red raspberry is the predominant agricultural crop in the region followed by significant areas of forage grass and pasture Zebarth et al Because shallow groundwater is younger and therefore more likely to reflect more recent landscape practices than deeper groundwater , only shallow wells with mid-screen depths less than 10m below the mean height of the water table were used. Prior to June , ECCC sampled monthly; however to reduce program costs, they began quarterly sampling thereafter i.

For Canadian wells, mean, median, minimum, and maximum nitrate were determined on a quarterly and annual basis. Many US wells had only one sample collected between Geospatial Data To assess contemporary land use and land cover, a variety of geospatial datasets were consolidated from US and Canadian sources Table 3.

Landscape Indicators: Assessing and Monitoring Landscape Quality - Google Книги

Together these datasets provided the best continuous coverage for the Canadian portion of the ASA region. To create a seamless cross-border mosaic, these datasets were harmonized to commensurate resolutions, formats, and classification schemes representing LULC categories consistent across the region. Comparison of characteristics of geodatasets from the US and Canada used in this chapter. Approach for improving concordance among these datasets is explained further in the text.

To determine linkages between LULC and nitrate concentrations, contemporary land use patterns e. In addition to the landscape indicators in Table 3. Due to build-up of root pathogens and viruses in soil, raspberry fields are typically renovated uprooted and replanted anew every years. Renovations include removal of root balls and old canes followed by tillage.

A critical component of renovations, aside from planting of new raspberry plants, is the addition of soil amendments typically poultry manure to increase soil nutrients. Renovations occur in the fall and the following spring manure is applied to bare fields and new raspberries are planted Forge It is during this application of manure in the spring when fields are bare that it is hypothesized intense leaching occurs Staver and Brinsfield In order to capture the dynamic nature of this regionally-abundant crop, Google Earth imagery was used to photo-interpret past renovations of raspberry fields i.

Further distinction was made among berry types: Berry production has been associated with high fertilizer use in the region. Berry field renovations Total Area of Renovations m2 Newly-planted and replanted raspberry fields m2 since Raspberries are fertilized heavily within the first 3 years of planting with declines in fertilizer application in subsequent years.

Manure is a source of nitrate. Throughout the ASA, the main source of nitrate to the aquifer is likely attributed to agriculture Zebarth et al. Large gravel mining operations in the ASA may contribute to surface and groundwater pollution. Impervious surfaces are not included in this category as they are included in urban. Denitrification in wetlands potentially reduces nitrate loading to surface and subsurface waters. Additional Co-variates Water Table Height m Mean height of the water table As water tables rise, increase leaching of nitrate to groundwater may be expected.

Depth of Mid-Screen Depth below water table m The mid-screen refers to the location in the well where water enters. The depth of this mid-screen determines depth below the average height of the water for water sampling. I used mean depth of screen casing from Depth is related to the movement of groundwater and is associated with the age of groundwater.

Hence, it can be expected that the deeper the mid-screen, the older the water being collected. Because groundwater moves both laterally and vertically in an aquifer USGS , radii of different sizes were evaluated to capture potential lateral water movement. Zones of 1 km radii were also evaluated but due to lack of statistical significance were not included here. I further incorporated a unique approach using upstream semi-circular zones of influence corresponding to the predominately-southwesterly direction of groundwater flow Figure 3.

While the zones of influence do not address residence time or aquifer volume both of which may be important to groundwater nitrate concentrations , they do help further explore directionality as well as the extent of landscape influence. Statistical Analysis First, to examine long-term trends in nitrate concentrations, I used Mann-Kendall MK tests to detect either monotonic upward or downward trends over time from A monotonic trend upward or downward means that a variable consistently increases or decreases over time, yet the trend may or may not be linear.

A positive MK score indicates an increase with time whereas a negative indicates the opposite. Though Mann-Kendall tests can be 45 computed for a time series with missing values, performance will be adversely affected. Therefore, missing values were interpolated using the mean value of the two years prior and two years after any missing quarterly samples.

Measurements collected in January replaced missing values in December Wells with more than 3 missing values throughout the time series were excluded. Long-term trend analysis was only conducted for Canadian wells as comparable long-term nitrate measurements were not available for US wells. Trend significance was mapped for each well. My second approach examined connections between nitrate concentrations and landscape indicators.

For wells located in Canada, measures of central tendency mean, median as well as minimum and maximum nitrate were determined annually as well as quarterly March, June, September, and December. For US wells only sampled once within the study period , a single nitrate sample value was used as the response variable. Backward stepwise regression was used to determine which landscape variables Table 3.

My goal was to seek the best models consisting of no more than independent variables to avoid model over-fitting.



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To accomplish this, the least significant variables in each model were sequentially omitted in the interest of parsimony as judged by their significance levels, partial R2 values, and AIC scores. Akaike information criterion AIC aids model selection by evaluating the relative quality or goodness of-fit of different statistical models and helps identify and penalize models which are over-fit with too many additional variables Burnham and Anderson Models with the lowest AIC score, given a similar number of independent variables, indicate the highest quality model.

Additional variables were warranted in a model only if they lowered the AIC by at least two points. Shapiro-Wilk tests were used to assess normality of independent and dependent variables and landscape indicators were transformed as needed using the arcsine square root transformation.

Nitrate concentrations in nine wells decreased from Figure 3. Two wells demonstrated a significant increasing trend over time Figure 3. The remaining four wells demonstrated no significant trends. Recall that trends could not be evaluated for US wells because long-term nitrate measurements were not available. In contrast, the lone nitrate sample available for each US well ranging from 0. Proportion of raspberries as well as forage and pasture land are important predictors of groundwater nitrate concentrations A total of 12 models were created 4 scales of influence x 3 response variables: The best model for each response variable is shown in bold Table 3.

Regardless of zone radii size, direction, or jurisdiction, the proportion of raspberries and forage and pasture most strongly and consistently explained groundwater nitrate concentrations. Proportion of mixed berries was positively associated with nitrate values in one model with a partial R2 value of 0. In contrast, proportion of raspberries was weakly negatively associated with nitrate in half of the models, with partial R2 values ranging from 0.

Proportion of forest and water table height were negatively associated with nitrate in one of the models each, with partial R2 values of 0. For all other models, changing the size of the zone of influence did not significantly change R2 values. My results show nitrate concentrations were strongly correlated e.

Ecological Indicators

The strength of these correlations supports the premise that land use affects groundwater quality in aquifers overlain by highly permeable materials. Previous studies using an allocation model for groundwater nutrient loads based on land cover classes, found similar results determining that average nitrate concentrations were highest beneath cropped fields and residential areas Schilling et al Other studies have found higher nitrogen concentrations in groundwater in watersheds dominated by agricultural as compared to forestry-dominated catchments Lawniczak et al For models of annual median nitrate, mixed berries were strongly and blueberries weakly positively correlated with nitrate while raspberries demonstrated a negative relationship.

In contrast, on the US-side of the aquifer where groundwater data were largely lacking, raspberries were positively correlated with nitrate, albeit weakly. Raspberries were the only berry type on the US-side to demonstrate a significant relationship of any kind with nitrate.

Reduced sampling effort frequency of observations collected on the US side may have also played a role and certainly would not represent temporal trends. Spatial scale of measurements An emphasis on LULC in circular areas surrounding water table wells is a simple and effective method for correlating land use and water quality Barringer et al I examined two spatial extents by measuring landscape indicators within and m distances surrounding wells.

Increasing the zone of influence improved model fit for two of the three 54 response variables. One might reasonably expect m zones of influence to improve model fit because landscape activities immediately surrounding groundwater wells might influence recorded nitrate concentrations in wells more than activities further away, however my results indicated the converse. One explanation is that the well screen depth of the wells sampled is sufficiently below the water table to capture water originally infiltrating further up-gradient than m Zebarth et al The m scale of measurement slightly improved model fit for annual median nitrate, however.

The radius size used in the literature has varied greatly, but is an important consideration. For larger radii, land within its perimeter contributes proportionally less water to a well, potentially weakening correlations between groundwater quality and land use. However, a smaller radius, approaching the size of the minimum mapping unit, might unduly influence derived landscape indicators via exclusion of important up-gradient features, susceptibility to localized positional errors in mapped features, or misidentification of fine-scale features within the zone.

Thus, selection of an appropriate zone of influence is important to maximizing the correctness of an association between land use and groundwater quality McLay et al Similar to my findings, other studies have found significant positive relationships between shallow aquifer nitrate concentrations and land use in estimated recharge zones within a m radius of wells Keeler and Polasky , Nolan et al , Kolpin , McLay et al My incorporation of berry field renovations associated with greater fertilizer application was a unique component of my landscape indicator approach and helps improve mechanistic understanding of potential N sources.

No prior studies have explicitly examined the number or areal extent of field renovations in this way, despite being a suspected source of nitrate. That field renovations showed a strongly significant positive correlation with annual median nitrate concentrations is consistent with renovated fields being heavily amended with poultry manure before being replanted with raspberries. As a result, information regarding N loading is largely unavailable for this region. Instead, crop types within a certain distance of wells was my proxy for N loading.

Although knowledge of crop type at a location helps indicate where inorganic and organic fertilizer is likely to be applied, it does not indicate the rate of actual application. The rate and timing of N fertilizer application vary based on regional and local factors including crop type, tillage practice, crop rotation, and irrigation practices and from farmer to farmer.

The relationship between these regional and local factors along with nitrogen use efficiency results in residual soil 56 nitrogen being susceptible to leaching into the aquifer after heavy periods of precipitation, despite the lack of direct measurements. Additional factors Factors not included in this study may help further explain nitrate in the aquifer. Additional sources of nitrate to groundwater may include septic tanks, lawn fertilizers, and domestic animals in residential areas Nolan et al Nitrate concentrations in groundwater on Nantucket Island, Massachusetts, increased with number of septic tanks and percentage of high-density residential and agricultural land and decreased with percentage of forest and undeveloped land Gardner and Vogel However, in my study region, studies indicate minimal influence of septic tanks Robertson et al Geological factors such as soil drainage type help explain nitrate concentrations Nolan et al Future research should take into account livestock production both poultry production present in Canada and dairy production present in the US across the aquifer.

Additionally, incorporating past land use into the models would help to capture lag-effects and account for legacy nitrate present across the aquifer. In the next chapter, I build off these results and address the persistence of landscape legacies in impacting measured groundwater nitrate concentrations. Lack of consistent data for evaluating transboundary systems is a global problem One major challenge of cross-border monitoring can be a lack of consistent data among governing jurisdictions.