Testing terrain: exploring the computational design of natural systems in landscape architecture

While the use of computational design methods in landscape architecture is not uncommon, they are rarely used to develop performance-driven design strategies. Throughout this thesis, I argue that this shortfall stems from disciplinary differences in the design process and designed medium that are not reflected in common computational design tools. The scope for better reconciling these disjuncts is broad, but especially acute when employing design strategies that consider the performance of complex natural systems. Here, the overlap between disciplinary intent and computational capability is significant as natural systems have unique representational, scalar, and temporal complexities and their design forms a core concern of landscape architecture. Computation offers new approaches to managing these complexities, but also introduces new challenges. I investigate these using a design research methodology that foregrounds the tool development as a reflective practice that can span across specific design contexts and general disciplinary concepts. In discursive terms, I identify that the aims of computational design broadly align with those emphasised in contemporary landscape architectural theory: to pursue dynamism through generative systems. This seeming similarity masks a difference whereby the agency of computational design systems acts within the design process while the agency of landscapes systems acts within the world. Using the generative techniques of the former to help design the generative effects of the latter creates representations that posses a novel capacity for explicit precision and projection alongside a corresponding increase in implicit uncertainty. As a result, I suggest that traversing the solution space of these models requires a distinct design strategy that emphasises tendency and feedback over convergence. Framing the use of computational design methods in this manner highlights their value and purpose when modelling complex natural systems. In technical terms, I identify that current computational design platforms tend to employ geometry as the locus of design resolution and data propagation. In doing so they marginalise many informal or aformal landscape conditions and thus limit the scope of modelling. I explore alternatives through a process of tool-making that tests how to create interoperable procedures that each represent different aspects of landscape systems. In many cases, the encapsulation of computational procedures — as both machinic instructions and interface affordances — can enact existing landscape architectural theories of representation, ecology, and emergence. This form of instrumentality offers a distinct, valuable, and under-developed form of disciplinary praxis. However, as I highlight, its execution requires successfully negotiating between two modes of abstraction: the representation of computational procedures as software and the representation of landscape architectural design intent as computational procedures. The strategies I develop to align these two forms of representation help create more accessible and flexible computational methods for modelling complex natural systems

Establishment and production from thinned mature deciduous-forest silvopastures in Appalachia

Paper presented at the 11th North American Agroforesty Conference, which was held May 31-June 3, 2009 in Columbia, Missouri.In Gold, M.A. and M.M. Hall, eds. Agroforestry Comes of Age: Putting Science into Practice. Proceedings, 11th North American Agroforestry Conference, Columbia, Mo., May 31-June 3, 2009.Past research has not adequately addressed effective management and utilization of silvopastures developed from the ubiquitous mature woodlots which comprise 40-50% of small Appalachian farm acreage. While some grazing in woodlots is common, a set of guidelines for optimal utilization of these areas is not. We thinned a white oak dominated mature second growth forested area establishing two 0.5 ha, eight-paddock, orchardgrass-perennial ryegrass-white clover silvopasture replications for comparison with two nearby open pasture replications. After thinning trees, silvopastures were limed, fertilized and seeded. Sheep were fed hay and corn scattered across the area to facilitate removal of residual understory and incorporation of applied materials into surface soil. We measured soil moisture in the top 15 cm using TDR and photosynthetically active radiation (PAR) using a system of 16, 1 m line Quantum Sensors during the subsequent growing seasons of 2004, 2005, and 2006. Paddocks were rotationally grazed by sheep with two 1 m2 herbage mass samples taken prior to animal grazing. There was no significant difference in soil moisture between silvopastures and open pastures however, there was adequate rainfall to prevent drought all three years. The two silvopasture replications had residual tree stands of 14.1 and 15.6 m2 ha-1 diameter breast height allowing 42 and 51 [percent] of total daily incident PAR compared to measurements in the open field. Total forage mass yield from open pasture for 2004, 2005 and 2006 was 9.9, 10.5 and 10.2 t ha-1 respectively and for silvopasture 8.5, 6.7 and 6.7 t ha-1. Silvopastures received 47 [percent] of open pasture incident PAR yet yielded an average of 72 [percent] as much herbage mass as the open pastures. The silvopasture soils were managed for forage production only a few years unlike the open pastures which received roughly a century of better management. Soil limitations may have contributed to decreased forage yield in silvopastures in addition to reduced PAR.C.M. Feldhake, J.P.S. Neel and D.P. Belesky ; USDA-ARS Appalachian Farming Systems Research Center 1224 Airport Road, Beaver, WV.Includes bibliographical references

Seedling Performance Associated with Live or Herbicide Treated Tall Fescue

Tall fescue is an important forage grass which can host systemic fungal endophytes. The association of host grass and endophyte is known to influence herbivore behavior and host plant competition for resources. Establishing legumes into existing tall fescue sods is a desirable means to acquire nitrogen and enhance the nutritive value of forage for livestock production. Competition from existing tall fescue typically must be controlled to ensure interseeding success. We used a soil-on-agar method to determine if soil from intact, living (L), or an herbicide killed (K) tall fescue sward influenced germination and seedling growth of three cultivars of tall fescue (E+, MaxQ, and E−) or legumes (alfalfa, red clover, and white clover). After 30 days, seedlings were larger and present in greater numbers when grown in L soil rather than K soil. Root growth of legumes (especially white clover) and tall fescue (especially MaxQ) were not as vigorous in K soil as L soil. While shoot biomass was similar for all cultivars of tall fescue in L soil, MaxQ produced less herbage when grown in K soil. Our data suggest establishing legumes or fescue cultivars may not be improved by first killing the existing fescue sod and seedling performance can exhibit significant interseasonal variation, related only to soil conditions

Winter Grazing in a Grass-Fed System: Effect of Stocking Density and Sequential Use of Autumn-Stockpiled Grassland on Performance of Yearling Steers

Winter grazing can help reduce the need for purchased feeds in livestock production systems, when finishing cattle on pasture. Our objective was to evaluate the influence of stocking density and grazing stockpiled forage on performance of yearling steers during winter. Three grasslands were winter grazed for two years: I, naturalized pastureland, and II and III, sown and managed for hay production during the growing season but grazed in winter. Two stocking densities were used: low 7.41 and high 12.35 steers ha−1. Herbage mass was estimated before and after each grazing event, and disappearance (consumption, weathering, and trampling) was the difference between both. Forage mass and residual differed by stocking density (SD), year (YR), and grazing interval (GI), and disappearance differed by YR and GI. Grass and dead constituents of botanical composition differed by YR and GI. No differences were found for legumes and forbs. CP differed by YR and GI, and NDF and ADF differed only by YR. Steer average daily gain was 0.15 kg d−1 in 2011 and 0.68 kg d−1 in 2012 and varied by YR and GI. Acceptable gains in 2012 may be a product of environmental conditions that influenced herbage mass and nutritive value during stockpile and animal behavior during winter

The Green Grasshopper: Approaches to Teaching Computational Design Methods in Landscape Architecture

As computational design methods grow more common in landscape architectural education and practice there is a growing need for pedagogical approaches that teach these new methods in the terms of our own discipline. In contrast to established approaches, that largely cater to the tasks involved in design buildings, a landscape context requires a re-framing of how computational methods are used; often involving a shift away from form and towards landscape dynamics as the prime driver of design development. This adaptation is discussed here in terms of several key approaches developed when using parametric modelling as part of a teaching practice across a range of contexts