Can Synthetic Grass Alleviate Allergies? Our Findings

Poly-Turf was a brand of artificial turf in the early 1970s, manufactured by American Biltrite of Wellesley, Massachusetts. It was the first specifically designed for American football, with a patented layered structure which included a "shock pad" between the artificial grass and the asphalt sub-surface.^[1] It used polypropylene for its artificial grass blades, rather than the nylon used in AstroTurf and 3M's Tartan Turf.^[2][3][4]

In the late 1960s, the natural grass surface at the Orange Bowl in Miami was constantly in poor condition,^[5] primarily due to heavy usage; 34 games were scheduled there during the 1968 football season.^[6]

Poly-Turf was installed at the city-owned stadium in 1970,^[7] and utilized for six seasons. The stadium was used for both college and professional football, primarily by the University of Miami Hurricanes and the Miami Dolphins of the NFL. It also hosted the eponymous New Year's Day college bowl game, Super Bowl games, and high school football.

The University of Nebraska Cornhuskers won the first three Orange Bowl games played on Poly-Turf, which included two national championships. The first Super Bowl played on artificial turf was played on Poly-Turf in the Orange Bowl in January 1971, when the Baltimore Colts defeated the Dallas Cowboys 16-13 in Super Bowl V. The next Super Bowl at the stadium was the final game played on Poly-Turf in Miami; Super Bowl X in January 1976.^[8] Its flaws received additional media exposure the week prior to the game,^[9] and Dolphins receiver Nat Moore documented them in a local article.^[10]

The longer polypropylene blades of Poly-Turf tended to mat down^[11][12] and become very slick under hot & sunny conditions.^[13][14][15] Other NFL owners were skeptical of the brand before the first regular season games were played in 1970.^[7] The field was replaced after two seasons,^[16][17] before the Dolphins' 1972 undefeated season.^[18] It was replaced by another Poly-Turf surface. While it had similar problems,^[19][20] it lasted longer than the first installation, and was used for four years. Over just six years, both installations deteriorated rapidly and some football players suffered an increasing number of leg and ankle injuries; some players claimed to trip over seams. Prior to the second installation in 1972, the city did not consult with the Dolphins about the replacement; Dolphins' head coach Don Shula preferred a different brand, either AstroTurf or Tartan Turf.^[21] The field discolored from green to blue due to the severe UV nature of the Miami sun.^[14][22]

The city removed the Poly-Turf in 1976 and re-installed natural grass, a special type known as Prescription Athletic Turf (PAT),^[23][24][25] which remained until the stadium's closure in early 2008. As late as December 1975, the city had planned to retain the Poly-Turf for the 1976 season,^[23] but that decision was changed a few weeks later, prior to the Super Bowl.^[8][26][27]

The Orange Bowl became the first major football venue to replace its artificial turf with natural grass, and it was the third NFL stadium to install Prescription Athletic Turf; Denver's Mile High Stadium and Washington's RFK Stadium installed PAT fields a year earlier in the spring of 1975.^[24]

Other NFL stadiums which installed Poly-Turf included Schaefer Stadium, opened in 1971 for the New England Patriots,^[11] and Tulane Stadium in New Orleans, home of the Saints, Tulane University, and the Sugar Bowl. Notable college stadiums included Legion Field in Birmingham, Alabama^[28] and Alumni Stadium at Boston College.^[29]

American Biltrite ceased production of Poly-Turf in 1973; 3M stopped the manufacture of its Tartan Turf in 1974, citing rising oil prices in light of the 1973 oil embargo.^[4] This left AstroTurf as the only major manufacturer of artificial turf (with only minor competition along the way) until FieldTurf was introduced in the late 1990s.^[30]

Landscape ecology is the science of studying and improving relationships between ecological processes in the environment and particular ecosystems. This is done within a variety of landscape scales, development spatial patterns, and organizational levels of research and policy.^[1][2][3] Landscape ecology can be described as the science of "landscape diversity" as the synergetic result of biodiversity and geodiversity.^[4]

As a highly interdisciplinary field in systems science, landscape ecology integrates biophysical and analytical approaches with humanistic and holistic perspectives across the natural sciences and social sciences. Landscapes are spatially heterogeneous geographic areas characterized by diverse interacting patches or ecosystems, ranging from relatively natural terrestrial and aquatic systems such as forests, grasslands, and lakes to human-dominated environments including agricultural and urban settings.^[2][5][6]

The most salient characteristics of landscape ecology are its emphasis on the relationship among pattern, process and scales, and its focus on broad-scale ecological and environmental issues. These necessitate the coupling between biophysical and socioeconomic sciences. Key research topics in landscape ecology include ecological flows in landscape mosaics, land use and land cover change, scaling, relating landscape pattern analysis with ecological processes, and landscape conservation and sustainability.^[7] Landscape ecology also studies the role of human impacts on landscape diversity in the development and spreading of new human pathogens that could trigger epidemics.^[8][9]

The German term Landschaftsökologie – thus landscape ecology – was coined by German geographer Carl Troll in 1939.^[10] He developed this terminology and many early concepts of landscape ecology as part of his early work, which consisted of applying aerial photograph interpretation to studies of interactions between environment and vegetation.

Heterogeneity is the measure of how parts of a landscape differ from one another. Landscape ecology looks at how this spatial structure affects organism abundance at the landscape level, as well as the behavior and functioning of the landscape as a whole. This includes studying the influence of pattern, or the internal order of a landscape, on process, or the continuous operation of functions of organisms.^[11] Landscape ecology also includes geomorphology as applied to the design and architecture of landscapes.^[12] Geomorphology is the study of how geological formations are responsible for the structure of a landscape.

One central landscape ecology theory originated from MacArthur & Wilson's The Theory of Island Biogeography. This work considered the biodiversity on islands as the result of competing forces of colonization from a mainland stock and stochastic extinction. The concepts of island biogeography were generalized from physical islands to abstract patches of habitat by Levins' metapopulation model (which can be applied e.g. to forest islands in the agricultural landscape^[13]). This generalization spurred the growth of landscape ecology by providing conservation biologists a new tool to assess how habitat fragmentation affects population viability. Recent growth of landscape ecology owes much to the development of geographic information systems (GIS)^[14] and the availability of large-extent habitat data (e.g. remotely sensed datasets).

Landscape ecology developed in Europe from historical planning on human-dominated landscapes. Concepts from general ecology theory were integrated in North America.^[when?] While general ecology theory and its sub-disciplines focused on the study of more homogenous, discrete community units organized in a hierarchical structure (typically as ecosystems, populations, species, and communities), landscape ecology built upon heterogeneity in space and time. It frequently included human-caused landscape changes in theory and application of concepts.^[15]

By 1980, landscape ecology was a discrete, established discipline. It was marked by the organization of the International Association for Landscape Ecology (IALE) in 1982. Landmark book publications defined the scope and goals of the discipline, including Naveh and Lieberman^[16] and Forman and Godron.^[17][18] Forman^[6] wrote that although study of "the ecology of spatial configuration at the human scale" was barely a decade old, there was strong potential for theory development and application of the conceptual framework.

Today, theory and application of landscape ecology continues to develop through a need for innovative applications in a changing landscape and environment. Landscape ecology relies on advanced technologies such as remote sensing, GIS, and models. There has been associated development of powerful quantitative methods to examine the interactions of patterns and processes.^[5] An example would be determining the amount of carbon present in the soil based on landform over a landscape, derived from GIS maps, vegetation types, and rainfall data for a region. Remote sensing work has been used to extend landscape ecology to the field of predictive vegetation mapping, for instance by Janet Franklin.

Nowadays, at least six different conceptions of landscape ecology can be identified: one group tending toward the more disciplinary concept of ecology (subdiscipline of biology; in conceptions 2, 3, and 4) and another group—characterized by the interdisciplinary study of relations between human societies and their environment—inclined toward the integrated view of geography (in conceptions 1, 5, and 6):^[19]

1. Interdisciplinary analysis of subjectively defined landscape units (e.g. Neef School^[20][21]): Landscapes are defined in terms of uniformity in land use. Landscape ecology explores the landscape's natural potential in terms of functional utility for human societies. To analyse this potential, it is necessary to draw on several natural sciences.
2. Topological ecology at the landscape scale^[22][23] 'Landscape' is defined as a heterogeneous land area composed of a cluster of interacting ecosystems (woods, meadows, marshes, villages, etc.) that is repeated in similar form throughout. It is explicitly stated that landscapes are areas at a kilometres wide human scale of perception, modification, etc. Landscape ecology describes and explains the landscapes' characteristic patterns of ecosystems and investigates the flux of energy, mineral nutrients, and species among their component ecosystems, providing important knowledge for addressing land-use issues.
3. Organism-centered, multi-scale topological ecology (e.g. John A. Wiens^[24][25]): Explicitly rejecting views expounded by Troll, Zonneveld, Naveh, Forman & Godron, etc., landscape and landscape ecology are defined independently of human perceptions, interests, and modifications of nature. 'Landscape' is defined – regardless of scale – as the 'template' on which spatial patterns influence ecological processes. Not humans, but rather the respective species being studied is the point of reference for what constitutes a landscape.
4. Topological ecology at the landscape level of biological organisation (e.g. Urban et al.^[26]): On the basis of ecological hierarchy theory, it is presupposed that nature is working at multiple scales and has different levels of organisation which are part of a rate-structured, nested hierarchy. Specifically, it is claimed that, above the ecosystem level, a landscape level exists which is generated and identifiable by high interaction intensity between ecosystems, a specific interaction frequency and, typically, a corresponding spatial scale. Landscape ecology is defined as ecology that focuses on the influence exerted by spatial and temporal patterns on the organisation of, and interaction among, functionally integrated multispecies ecosystems.
5. Analysis of social-ecological systems using the natural and social sciences and humanities (e.g. Leser;^[27] Naveh;^[28][29] Zonneveld^[30]): Landscape ecology is defined as an interdisciplinary super-science that explores the relationship between human societies and their specific environment, making use of not only various natural sciences, but also social sciences and humanities. This conception is grounded in the assumption that social systems are linked to their specific ambient ecological system in such a way that both systems together form a co-evolutionary, self-organising unity called 'landscape'. Societies' cultural, social and economic dimensions are regarded as an integral part of the global ecological hierarchy, and landscapes are claimed to be the manifest systems of the 'total human ecosystem' (Naveh) which encompasses both the physical ('geospheric') and mental ('noospheric') spheres.
6. Ecology guided by cultural meanings of lifeworldly landscapes (frequently pursued in practice^[31] but not defined, but see, e.g., Hard;^[32] Trepl^[19]): Landscape ecology is defined as ecology that is guided by an external aim, namely, to maintain and develop lifeworldly landscapes. It provides the ecological knowledge necessary to achieve these goals. It investigates how to sustain and develop those populations and ecosystems which (i) are the material 'vehicles' of lifeworldly, aesthetic and symbolic landscapes and, at the same time, (ii) meet societies' functional requirements, including provisioning, regulating, and supporting ecosystem services. Thus landscape ecology is concerned mainly with the populations and ecosystems which have resulted from traditional, regionally specific forms of land use.

Some research programmes of landscape ecology theory, namely those standing in the European tradition, may be slightly outside of the "classical and preferred domain of scientific disciplines" because of the large, heterogeneous areas of study. However, general ecology theory is central to landscape ecology theory in many aspects. Landscape ecology consists of four main principles: the development and dynamics of spatial heterogeneity, interactions and exchanges across heterogeneous landscapes, influences of spatial heterogeneity on biotic and abiotic processes, and the management of spatial heterogeneity. The main difference from traditional ecological studies, which frequently assume that systems are spatially homogenous, is the consideration of spatial patterns.^[33]

Landscape ecology not only created new terms, but also incorporated existing ecological terms in new ways. Many of the terms used in landscape ecology are as interconnected and interrelated as the discipline itself.

Certainly, 'landscape' is a central concept in landscape ecology. It is, however, defined in quite different ways. For example:^[19] Carl Troll conceives of landscape not as a mental construct but as an objectively given 'organic entity', a harmonic individuum of space.^[34] Ernst Neef^[20][21] defines landscapes as sections within the uninterrupted earth-wide interconnection of geofactors which are defined as such on the basis of their uniformity in terms of a specific land use, and are thus defined in an anthropocentric and relativistic way. According to Richard Forman and Michel Godron,^[22] a landscape is a heterogeneous land area composed of a cluster of interacting ecosystems that is repeated in similar form throughout, whereby they list woods, meadows, marshes and villages as examples of a landscape's ecosystems, and state that a landscape is an area at least a few kilometres wide. John A. Wiens^[24][25] opposes the traditional view expounded by Carl Troll, Isaak S. Zonneveld, Zev Naveh, Richard T. T. Forman/Michel Godron and others that landscapes are arenas in which humans interact with their environments on a kilometre-wide scale; instead, he defines 'landscape'—regardless of scale—as "the template on which spatial patterns influence ecological processes".^[25][35] Some define 'landscape' as an area containing two or more ecosystems in close proximity.^[15]

Hybrid grass or reinforced natural grass is a product created by combining natural lawn grass with reinforcing synthetic fibres. It is used for stadiums^[1] and training pitches used for association football,^[2] rugby,^[3] gridiron football^[4] and cricket.^[5] Reinforced natural grass can also be used for events and concerts. The synthetic fibres incorporated into the rootzone make the grass stronger and more resistant to damage.^[6]

A first generation of hybrid grass appeared in the 1990s. Grass roots were allowed to intertwine with a mix of soil and synthetic fibres as they grew.^[6] Three main methods exist to insert synthetic fibres in the root zone. The first is to inject fibres in the sand with a tufting machine.^[7][8]

The second method is to mix fibres, cork and sand in an automated plant and to install it afterwards on the pitch. The system was created by a laboratory at Arts et Métiers ParisTech.^[9][10][11]

The third method is to put a carpet or mat with woven or tufted fibres on the surface, then to brush in sand or sand mixes to keep the fibres in an upright position and finally to seed grass mixtures on top. The natural grass roots through the mat and stabilizes the system. These systems are called carpet-based hybrid grass solutions.^[12]