DESIGN PRINCIPLES OF LANDSCAPE ARCHITECTUREDESIGN PRINCIPLES OF LANDSCAPE ARCHITECTUREDESIGN PRINCIPLES OF LANDSCAPE ARCHITECTURE
COMPOSITE LANDSCAPE
Every individual perceives the landscape uniquely, influenced by various everyday elements such as sounds, scents, and visuals The composite landscape is formed by the interplay of landforms, vegetation, and built structures, shaping our experiences as we navigate through different spaces and transitions Therefore, designing a comprehensive landscape requires the thoughtful integration of these elements into a cohesive and often intricate whole.
The relationship of each space within a composite landscape hinges on two crucial factors: the organizational structure we implement for related spaces and the characteristics of the transitions between neighboring areas.
In his 1996 book, "Architecture: Form, Space, and Order," architect Francis Ching explores various configurations of rooms, courtyards, squares, and streets Through this study, we can identify three distinct types of architectural arrangements.
A linear organization consists of a sequential arrangement of spaces connected by a single circulation route, allowing for either sequential or parallel access to each area This progression can take various forms, including straight, angled, curved, or irregular paths, but remains continuous with a defined start and finish Each space within this series can vary in size, shape, and function, contributing to the overall design.
The spaces within a line are important due to their arrangement and context, while the spaces at the beginning and end hold distinct significance as they mark the start and finish of the sequence This linear arrangement of spaces is viewed as a progression through specific locations, potentially leading to a climax or goal.
Ching illustrates that concentrated areas develop a new organizational structure based on their proximity to each other, a pathway, or an entry point He also explores the role of symmetry in organizing these clusters effectively.
The axis of symmetry links and reflects the regions it separates while also functioning as a perceptual, if not physical, path
A well-designed city plaza or performance venue serves as a central gathering and distribution area, offering access to surrounding spaces Its strategic location enhances connectivity, making it a vital and prominent space within the urban landscape.
The linear progression of spaces, as illustrated in Figure 1.1, is exemplified by the tree avenues and woodland clearings along the River Skell in Studley Royal, North Yorkshire, leading to the historic ruins of Fountains Abbey, shown in Figure 1.2.
A larger enclosure can encompass multiple spaces, exemplified by Ching's concept of a 'centralized organization.' These enclosed areas can either be fully self-contained, clearly separated from their surroundings, or they may maintain a distinct identity while still being part of a larger environment.
A contained organization relies on the relative sizes of its constituent spaces for effectiveness, unlike linear series and clusters When a contained space is significantly smaller than the surrounding area, it takes on the characteristics and role of a center within the larger space Rather than being perceived as an independent area to explore, it is viewed by the dominant space as an object.
Figure 1.3: Clustered spaces related by proximity
Figure 1.4: Circulation of clustered spaces
Figure 1.5: Hidcote Manor, Gloucestershire A complex of spaces clustered around the Theatre Lawn and organized about two major axes at right angles
A spatial hierarchy can be structured either vertically or horizontally, similar to job hierarchies within an organization The number of levels in this hierarchy is influenced by the purpose and composition of the spatial arrangement.
In his book Exterior Design in Architecture (1970), Ashihara listed the following pairs of opposites
Exterior interior public private big groups small group amusement quiet, artistic sport non-movement, cultural
Figure 1.6: Types of contained spatial organization
The Tiltyard at Dartington, Devon, UK, is characterized by ancient terraces enhanced with tree and hedge planting, creating a significant gathering space This area is surrounded by woodland and serves as a central hub for several smaller garden spaces.
The park depicted in Figure 1.8 was built atop a car park as part of the Canary Wharf development in London during the 1980s It serves as a safeguarded green area amidst the expansive structures and adjacent roadways, featuring a unique two-tiered design that enhances its contained organization.
Any one space will fall somewhere between these two extremes, therefore knowing and expressing where each constituent space falls in the hierarchy is essential to creating a successful composite space
The spatial hierarchy between interior and exterior environments can be developed to create a progression where each area offers greater protection and confinement than the one before.
The transition from an open outdoor space to a fully enclosed indoor environment can occur in a single step This shift highlights the hierarchy between outdoor and indoor spaces, which is defined by varying degrees of enclosure and permeability.
VISUAL PROPERTIES OF PLANTS
Subjective and Objective Responses to Plants
As professional designers, it is essential to develop a planting aesthetic model that accommodates the diverse responses individuals have to various plants and their combinations This approach enables us to effectively cater to the wide array of people, places, and functions we encounter in our work.
When it comes to objective plants, individuals may have varying interpretations and preferences; however, there tends to be a consensus on key characteristics such as growth habits, leaf shapes, and, to a lesser degree, color.
Subjective plants refer to the personal interpretations of objective plants, where various species carry significant associations and symbolic meanings for both individuals and cultural groups.
The Analysis of Visual characteristics
The visual properties of form, line, texture, and color are essential for analyzing the appearance of individual plants or plant groups While these elements may be more abstract than specific features like flowers, fruits, and autumn displays, they are crucial for understanding composition and effectively combining plants to create a visually appealing arrangement.
The form of a plant refers to its three-dimensional shape, which can be observed from multiple angles and distances These varying perspectives and scales significantly influence our understanding of the plant's structure.
Form is an important aesthetic criterion for species selection
Prostrate plants, including various shrubs and perennial herbs, exhibit a unique flat and spreading growth form Some shrubs develop woody stems that rise above the ground while forming low, horizontally spreading masses of foliage.
Carpeting plants are characterized by their dense, uniform canopy that remains close to the ground These plants often spread rapidly through robust underground stems, making them an effective choice for ground cover.
• Hummock, Dome and Tussock Forms:
Many low-growing plants develop by means of a gradually increasing rootstock rather than by vigorous, searching, propagating stems
The term "hummock" describes clump-forming herbaceous plants and smaller shrubs, while "dome" refers to larger shrubs and trees that share a similar canopy shape.
DOME FORM This is a larger version of the shape of the hummock plants
TUSSOCK FORM Also known as bunch form, this shape is common among monocotyledonous plants, including many grasses and sedges, such as some of the fescues
Domed and rounded trees and shrubs tend to have a significant number of spreading and low-angled branches, while erect and ascending forms are defined by predominantly vertical or sharply angled main stems and branches.
The overall shape is like a sheaf of wheat with the stems gathered in at the base but sprayed out towards the top
This growth form resembles the arching habit previously mentioned but is characterized by a distinct stem that can reach heights of twenty meters or more Predominantly found in palm trees and tree ferns, it features a tall, straight main stem or multiple stems, with all leaves emerging in a rosette from the single growing point at the top of the stem.
Succulents, similar to palms and tree ferns, exhibit a unique variety of forms that can be characterized as 'sculptural.' Their striking three-dimensional shapes command attention, making them a captivating focal point in any setting.
The resulting shape is typically oval or egg-shaped, which is more commonly found in selected cultivars than in wild species This is primarily due to the preference for an upright oval form in urban and garden settings where lateral space is limited.
The conical shape is commonly observed in conifers and certain broadleaf species Characterized by a tall crown that tapers to a sharp point, this form results from a consistent branching pattern A single, straight trunk supports numerous primary branches, contributing to the tree's distinctive conical appearance.
Fastigiate trees and shrubs are typically selected clones, making them rare in their natural habitat These trees feature a crown composed of numerous short, upward-growing branches, resulting in a dense and well-defined canopy.
• Tabulate and Level Spreading Form
Tabulate and spreading forms provide trees and shrubs with a stable yet lightweight character, as their layers of foliage are elevated, allowing light and air to filter through the branches.
Principles of visual composition
In planting, the most important are the principles of harmony and contrast, balance, emphasis, sequence, and scale
Harmony in design is achieved through the relatedness of similar plant forms, textures, line characteristics, and closely related colors The stronger the aesthetic connection among the plants, the greater the sense of harmony created in the space.
Why do harmony and contrast have to be together?
We interpret our perceptions through the lens of familiarity, identifying patterns of similarities and differences to make sense of our surroundings This interplay of harmony and contrast is essential, as they are interconnected and cannot exist independently.
In planting composition, achieving a balance of harmony and contrast is essential The visibility and impact of contrast between two species are enhanced when there is an element of harmony present This approach is particularly effective when contrasting characteristics, such as leaf texture, are utilized.
Harmony in design is achieved by combining elements like leaf color and flower color, creating a more satisfying visual experience This effect is enhanced when varied and contrasting forms and textures are linked through these harmonious color choices.
Excessive contrast in design can lead to illegibility, as it creates a lack of related elements and obscures overall patterns A chaotic mix of plants with strong contrasting features makes it challenging to appreciate individual qualities and the overall composition Such restlessness can be distracting, highlighting the importance of restraint as a key quality in creating enduring and refreshing designs.
Balance in a composition arises from the relationship between vegetation masses, influenced by their size, position, and visual energy Achieving visual balance requires that the components possess visual force and that there is a fulcrum or axis around which this force operates The arrangement of plant masses and elements around this axis enhances its significance, often making it the focal point of the space The most straightforward form of balance is bilateral symmetry, where the planting arrangement on one side of an axis mirrors that on the opposite side While compositions may feature one or two axes of symmetry, they can also possess multiple axes, as seen in circular arrangements with infinite axes of symmetry.
Symmetry in design is often linked to formality, showcasing abstract and ordered patterns that reflect rational thought This control over form highlights humanity's technological prowess in shaping the landscape's materials The striking nature of symmetrical forms stands in contrast to the organic shapes that arise without deliberate planning.
Balance can be attained without symmetry, where visual stability is achieved through the equilibrium of varying qualities around an axis or fulcrum For instance, a prominent form can counterbalance a coarse texture, while an assertive line can balance out intense colors.
A small quantity of a prominent characteristic can effectively balance a larger quantity of the same characteristic that is less pronounced For instance, a single plant with striking, sword-like leaves can harmonize with a group of three to five smaller plants that have ascending linear leaves of a similar shape but finer texture This balance is achieved through the potential energy created by the positioning of the plant masses, which is influenced by both their mass and relative height Consequently, a smaller plant in a dominant location can successfully balance a larger plant mass positioned subordinate to it.
Achieving visual stability in planting occurs when elements are balanced around an axis or center, whether through symmetry or equal energy distribution This balance can incorporate dynamic features and striking contrasts, yet all components remain cohesively unified Such arrangements, characterized by mass or energy equalities and stable, non-symmetrical forms, are often referred to as possessing occult balance.
Accent planting enhances important features and locations by incorporating visually striking plants This technique effectively highlights elements such as entrances, steps, seating areas, or water features In some cases, the plants themselves become the focal point of the space, reinforcing the concept of accent planting.
Emphasis and accent planting effectively draw attention through their striking qualities and thoughtful arrangement, guiding the eye to a focal point This technique is closely tied to contrast, as strong differences in appearance can captivate viewers A single plant that contrasts with its surroundings can serve as a powerful accent, enhancing the overall visual impact.
Sequence refers to how the visual elements of a planting composition evolve before the observer It can be perceived from a single viewpoint, showcasing a blend of colors, textures, or shapes within one scene, or it can be experienced as a series of scenes that reveal themselves as we navigate through the landscape.
Sequence is essential to the dynamic qualities of composition It is an expression of change
Visual composition connects individual elements to the overall whole, both in a static context and over time Sequence in visual art is comparable to rhythm in music or meter in poetry, offering a temporal framework for the composition Similar to musical rhythms or poetic structures, planting sequences can be straightforward with regular accents or more intricate, featuring overlapping patterns of repetition Additionally, these sequences can be intentionally chaotic or random, reflecting the dynamics of disorder.
Scale can be understood most simply as relative size Ching (1996) defines scale as either
In landscape design, the concept of generic scale pertains to the size relationships among different elements within a space and their alignment with the human body's dimensions It emphasizes how the relative sizes of individual plants and their groupings contribute to the overall composition of the landscape.
Plant Assemblages
This section will explore the essential ecological and horticultural factors that influence the success of plant communities By grasping these critical elements, we can ensure that our planting designs flourish as envisioned and remain sustainable with minimal maintenance requirements.
In natural or semi-natural plant communities, each species thrives by effectively acquiring the light, moisture, and nutrients essential for its survival Every plant is adapted to its specific ecological niche while engaging in direct or indirect interactions with other community members.
Plant species are distributed both horizontally and vertically Horizontal distribution is influenced by ground conditions such as soil nutrients and moisture, as well as atmospheric factors like wind exposure, light, and precipitation In contrast, vertical distribution is primarily determined by the inherent growth forms of the plants and the prevailing atmospheric conditions.
There are two principles that can be applied to the design of planted assemblages of all kinds
The groundcover principle indicates that a well-developed plant community thrives under favorable conditions, characterized by complete ground coverage at various levels A healthy ecosystem maintains year-round coverage with living vegetation or a thick layer of organic debris, while bare soil signifies significant environmental stress, which may stem from factors such as low water availability, poor soil aeration, nutrient deficiency, toxicity, excessive compaction, or frequent disturbances.
The complexity principle states that plant communities in favorable environmental conditions tend to increase in complexity over time However, this complexity can be diminished by various forms of interference, whether natural or human-induced, which may reset or hinder the development process Complexity can be evaluated based on three primary criteria.
1 the variety of species present: species diversity (this is equivalent to local bio-diversity),
2 the number of canopy layers present: structural diversity,
3 diversity through the seasons: seasonal diversity
Species and structural diversity serve as a protective buffer against environmental pressures, including climate change and variations in biotic factors like disease, grazing, and human interference A diverse array of species enhances the potential for adaptation to environmental changes, while a robust physical structure helps mitigate the impacts of climatic and soil factors.
Spatial structures in mountain beech forests provide designers with opportunities to evoke various moods and serve practical functions The openness and accessibility of these environments foster spaces that encourage human participation, especially in recreational activities.
Creating inviting spaces with basic amenities and thoughtful management encourages activities like walking, playing, cycling, and dining Conversely, dense lowland bush acts as a barrier, effectively separating and enclosing areas For optimal shelter and a clear spatial boundary, this type of planting structure is highly effective.
Designing complex mature forest structures is one option, but establishing them in cleared areas or grasslands can be challenging and time-consuming While a mature forest may be the long-term goal, simpler canopy structures are often more practical for initial objectives in many projects.
This article is divided into two sections: the first focuses on the cool temperate deciduous woody plant community structures prevalent in Britain, Europe, and parts of North America, while the second highlights evergreen structures typical of temperate to warm-temperate climates, such as those in New Zealand In the descriptions of the 135 plant assemblages, the names of the layers are delineated by slashes (/), with poorly developed layers indicated in brackets.
Deciduous Cool Temperate Communities (Europe and North America)
TREE CANOPY/(SUB-CANOPY)/SHRUB LAYER/HERB LAYER
Exotic groves, found in urban parks and gardens, are miniature versions of native forests, featuring scattered trees that reach heights of 8–12 meters instead of the typical 20–25 meters of forest canopies These ornamental woodlands often exclude dominant forest trees, focusing instead on the sub-canopy Despite their small size, sometimes as little as 100 square meters, they still exhibit the unique canopy structure characterized by three or more overlapping layers.
Figure 4.1: Three-layer canopy structures
A multi-layer forest or woodland structure provides essential benefits such as shelter, wildlife habitat, visual enhancement, environmental education, and opportunities for informal recreation This diverse and aesthetically rich environment, whether naturalistic or ornamental, maximizes plant value per area by utilizing vertical space effectively It allows trees to thrive above shrubs, which in turn grow above perennials, bulbs, and groundcover, creating a harmonious ecosystem.
TREE CANOPY/SUB-CANOPY/SHRUB LAYER/FIELD LAYER: EDGE OR MARGIN
The edges of woodlands and forests exhibit a gradual transition in canopy heights, ranging from tall trees to smaller shrubs and grasses This boundary is influenced by factors such as climate, topography, and land management practices The woodland edge can expand as forests encroach on open areas or contract due to human activities and natural disturbances Regardless of these changes, the canopy structure and species composition at the edge adapt to the increased light and exposure compared to the interior of the forest.
A woodland edge canopy can be effectively created using exotic and ornamental species, featuring a gradual height increase from front to back to showcase each layer To enhance ornamental associations, it's beneficial to incorporate multiple layers, including bulbs, herbaceous plants, and sub- and dwarf shrubs beneath taller species This approach requires a more gradual height transition and increased width for optimal effectiveness A typical ornamental edge structure with graduated height includes various plant layers.
1 front edging and groundcover of prostrate shrubs or low herbs, perhaps with spring and autumn bulbs and other small herbaceous plants emerging through them at various seasons;
2 low shrubs, sub-shrubs and tall herbaceous perennials;
3 medium-height shrubs and, behind and above these:
Small- and medium-height trees should be strategically grouped or scattered across different layers, considering the aspect and sun direction to prevent excessive shading of lower layers To minimize shade from their expansive canopy, tall forest tree species should be positioned at the back of the edge.