New Challenges in Plant Selection

soil conditions, and annual rainfall requirements can be expected to perform and survive and thus be good choices when the landscape architect is developing a planting design. A successful planting design is one where the landscape architect thoroughly thinks through not only the aesthetic and functional requirements identified during site analysis and design investigation but also considers the environmental and horticultural conditions and requirements in developing an appropriate plant species palette. Plants that are native to the region or imported from locations with comparable climate, soil, and moisture characteristics should Figure 7.6 Deciduous trees planted along building windows to provide shade in summer and allow sunlight and heat gain be expected to do well. Additional research should be conducted for non-native plants to make sure in winter. Asunaro Building in the Woods, Reitaku University. they will thrive in the new location. Consideration Courtesy of Keikan Sekkei, Tokyo, Japan. of the moisture requirements of plants has become increasingly important in the twenty-first century. Growing awareness and concern about the impact of climate change and water shortages are becoming an increasing priority and in some regions a requirement7 in planting design. Plant selection in regions experiencing water scarcity and rising annual temperatures is, by necessity, favoring the use of native species, species with a long history of adaptability to the region and plants capable of thriving with minimum or no irrigation. Figure 7.6 presents a beneficial use of plants in the built landscape. Deciduous trees were planted along the front of the windows of a library. The deciduous trees will moderate the extremes of climate by providing shade during the summer months to block the heat from the sun, thus reducing air conditioning costs. In the winter when they drop their leaves, sunlight is allowed inside the building to increase heat gain, thus reducing building heating costs.

Landscape architects are finding new challenges in working in nontraditional landscapes and site conditions. For instance, in developing plans for wetland restoration, landscape architects are selecting plants adapted to seasonal flooding such as runoff retention systems, including bio-swales and rain gardens. Conversely, landscape architects practicing in arid regions must develop a specialized knowledge of plants tolerant to drought conditions and the need to apply xeriscaping8 methods to conserve water. Landscape architects working with the new challenges have come to appreciate a new plant aesthetic sensibility. With this new design aesthetic, they find that they must educate their clients to appreciate the aesthetic merits, using endemic plants from the region. A new planting design vocabulary can be particularly challenging for clients coming to an arid environment from sub-tropical and temperate areas with higher rainfall and lower temperatures. Dense, multi-layered landscape designs found in temperate regions may not be practical in the clients’ new arid location. While at one time a formidable obstacle, the public has become increasingly tolerant, if