Participants chose and arranged support species for their services, including nutrient cycling, attracting beneficial animals and insects, mitigating erosion with their root structures, and providing wind breaks, privacy, and shade with thick foliage. For a review of the representation of product and service plant properties in community-authored and referenced artifacts, see the inclusion properties discussion onecosystem services that appealed to humans and supported the local ecology .Participants used plants’ growing conditions to determine their suitability for the sustainable polyculture. Participants referred to two categories of growing conditions — a plant’s needs and tolerances. Needs are the ideal inputs for a plant so it thrives, such as amount of sunlight, amount of water, and amount and kinds of nutrients. Plant nutrient, water, and sunlight needs were crucial to every design and featured in nearly every community-produced and referenced plant lists . Needs are also the ideal inputs for a plant to reproduce, such as serotiny. Serotiny is a plant’s requirement for particular ecological conditions, such as fire, to release seeds. Tolerances are the conditions that a plant can survive with, plastic growing bag including exposure to pests, soil pH, wind, salt, and shade. Participants considered tolerances depending upon the environmental conditions for which they were designing.
For example, many participants in the Live Oak community, who are exposed to seasonal hurricanes, wanted to know the wind, humidity, and flood tolerance of a plant, where as Manzanita participants, who live in a Mediterranean costal climate, wanted to know the drought and salt tolerance of plants. The community-referenced books encouraged assessing a wide range of growing conditions in sustainable polyculture design, almost all pertaining to the soil, water, and sunlight needs of the plants. Soil is the medium in which most plants grow, and the condition of soil determines if a plant will thrive, struggle, or die. Soil is created by organisms, such as fungi, bacteria, and insects, that break down plant debris. The nature and amount of the plant debris and the organisms in the soil, in addition to the local geology, determine the quality and makeup of the soil. Weiseman, Halsey, and Ruddock encourage a detailed analysis of soil conditions including soil regimes , soil pH, nutrients available or missing, salinization, toxic contaminants, and extreme climate disturbances that can drastically alter the state of the soil, such as extended droughts or heavy rains followed by mudslides. Hemenway argues that in addition to knowing the soil’s physical qualities for sustainable polyculture design, it is also important to consider the organisms that build and change the soil, such as bacteria, fungi, worms, and other insects. Water is the medium through which plants pull nutrients from the soil, therefore the frequency of rain, depth of water table, and drainage of soil define how much and how often a plant can take in nutrients.
Lancaster demonstrates how to understand and manage water flow across a landscape in ways that are productive for sustainable polyculture growth and production, particularly in regions that experience seasonal droughts. Moreover, he demonstrates how water-managing earthworks without vegetation are ineffective because the soil washes away without plant roots to hold it together. Plants use sunlight to photosynthesize. Some, however, can tolerate relatively low levels of light while others require far more. Many authors of the community-referenced texts demonstrated how to choose and place plants based on their daily and seasonal sunlight needs and the path of the sun over the sustainable polyculture site .Participants also considered plants’ intrinsic characteristics when arranged plants in a sustainable polyculture design. What participants refer to as intrinsic characteristics are known in formal plant sciences as plant traits . Sustainable polyculture design incorporates morphological and phenological functional plant traits. However, given the design process and varying degree of participants’ formal education in related fields, the level of detail of morphological and phenological traits in a functional plant traits database like the TRY database is beyond the needs and comprehension of most participants in the permaculture communities. The intrinsic characteristics I observed participants most commonly use in sustainable polyculture design were a plant’s height spread and canopy density at maturity, vertical layer in the polyculture , whether the plant was deciduous or evergreen, seasons of growth, and seasons to collect yield.
The intrinsic characteristics helped participants determine the spatial layout of a sustainable polyculture. For example, shorter plants that need shade can grow in the understory of larger evergreen trees.Participants also consulted images for what the plant looked like. Images of plants helped participants process the intrinsic characteristic data and visualize how the species may be used in a sustainable polyculture they’re designing. Participants said that images of the plant helped them gain a sense of the aesthetic appeal of a plant, get a sense of the variation of form in a species, and visualize the size in comparison to other species. The community-referenced materials suggested consideration of a wider range of intrinsic characteristics than I observed participants use regularly in their design process or were featured on community-authored plant lists. The community-reference materials recommended also including life span, years of productivity, root form, time to maturity, time to harvest, places of origin, places of naturalization, places of invasion, grafted versus not, nut-to-shell and flesh-to-pit ratio, and self-fertile versus requiring cross-pollination with another plant. The more-experienced community members that participated in the design workshop explained that they too considered many of these additional intrinsic characteristics in their personal practice. During instruction, however, a complete list of potentially important intrinsic characteristics was not reviewed. Instead instructors worked with students on their understanding of the complex relationships between plants, only discussing the intrinsic as they were relevant in a case-by-case basis. I included most of these additional intrinsic characteristics in the plant database because the experienced participants of the design workshop emphasized that these were factors they should be considered in sustainable polyculture design.When communicating with each other, most participants referred to plants by common names, and many participants did not know the scientific names of the plants they were referring to. Participants had a wide range of education regarding plant sciences, from none at all to graduate level education and common names were used as the shared language between amateurs and experts. In the educational settings I participated in, participants spoke about plants in a common rather than scientific vernacular because many participants were more familiar with plant’s common name than scientific. At times, the common vernacular was so far removed from a reference source that it became hard for a participant to determine the scientific name for a plant from areference source. If a participant received a cutting of a plant from another community member and its common name is used for any number of distinct species, it becomes more challenging for the participant to correctly identify the plant. For example, participants used the common name “cranberry hibiscus” to refer to both Hibiscus acetosella, a sorrel with red foliage with sour-tasting edible leaves, and Hibiscus sabdariffa, a sorrel with green foliage and dark red flower sepals that are commonly used for hibiscus tea. Participants that had grown both and were aware of the distinction between them were able to use photos to distinguish which scientific name and plant properties belonged to the plant they were referring to. However, wholesale grow bags newcomers looking for information on “cranberry hibiscus,” a plant they have only heard about but never grown, often conflated the two plants. Despite the communities’ frequent use of common vernacular for plant names, the imprecise nature of common names does not facilitate a clear organization of the information within the database. Instead, the plant database should use scientific names for organizing the plant data. A single species of plant could have many subspecies, varieties, cultivated varieties, or forms. Furthermore, many plants are hybridized across species , across variety , or across genus . For example, many citrus trees are hybrids – Persian lime is a hybrid between a key lime and a lemon – Citrus x latifolia, and a Meyer lemon is a hybrid between a lemon and a mandarin orange – Citrus x limon. Putting plant entries at the most granular level will exclude plants that don’t have a species, like intergeneric hybrids or lead to large amounts of redundant data.
Subspecies, varieties, and cultivated varieties often have more numerous and significant differences, but the commonalities are typically much greater than the differences. For an extreme example, the only difference in one unique form of a plant compared to another could be the color of the plant’s flower, with all other data being the same. For example, Prunus lusitanica L. f. myrtifolia is a form of Portugal laurel with darker, smaller, slower growing leaves than the base species. Most plant records are created at the species level, meaning each plant-record name has a distinct scientific name . To avoid redundancy of information, variations on species such as subspecies, varieties, cultivated varieties, and forms that have few differences from the species it is a variation of should be represented as alternate properties on the associated species plant card. Conversely, species that have significant differences across variations should each have their own plant record. For example Brassica oleracea, a species that includes cultivated varieties such as broccoli, kale, cabbage, cauliflower, Brussels sprouts, and collard greens. However, determining the point at which the differences are significant enough to warrant an independent entry into a plant database and the process of evaluating those differences to make that determination are still open questions. Another challenge lies in the fact that taxonomic classification for some of these plants are disputed – for example plants in the genus Sambucus, commonly referred to as “Elder,” has long been the subject of classification restructuring because plants within the genus exist in many parts of the word and have significant morphological differences . Although plant cards are associated with a scientific name, in these cases, a plant card will need to be associated with multiple scientific names. Representing multiple plant attribute contexts. When designing sustainable polycultures, plant attributes are evaluated from multiple contexts: intrinsic attributes, ecosystem attributes, and common uses for humans. Some attributes are distinctive to a plant regardless of the ecosystem it is planted in or a human’s socio-cultural relationship with it , and so should be defined without reference to an external context in the SAGE Plant Database. However, the attributes that vary depending on the climate region it is planted in should be defined per climate region. Though there may be differences in attribute definitions at more granular contexts, like microclimates, it is unclear if this level of detail is necessary for sustainable polyculture design. Humans have socio-cultural relationship with plants that dictate how humans observe, interact, grow, and use plants. Ethnobotanical information is subjective and varies depending on the culture and tradition of the human using the plant. Thus, ethnobotanical data requires a different representation in the database from the more explicit and well-defined biological relationships between plants and other ecosystem constituents, including humans. Through these data, the socio-cultural values of the content contributors will be embedded in the information in the database. A plant’s relationships with other non-plant organisms in the agroecosystem are often essential in sustainable polyculture design. Many relationships between plants can be directly determined by comparing values of similar or corresponding properties. However, sometimes the relationships among plants are based on their relationship with a third-party organism that is not a plant . For example, one plant may attract an insect while another plant repels that insect. That same insect may be essential to a third plant’s ability to complete a successful reproductive cycle. Specifically, wasps are attracted to nectary plants, are believed to be repelled by marigold and eucalyptus, and are essential to a fig tree’s reproduction cycle. Regarding how to represent plant relationships with organisms from other taxonomic kingdoms, I only focus on animals, including insects and humans, in the scope of this dissertation . Other kinds of organisms, such as non-edible fungi and bacteria, also play a crucial role in maintaining agricultural ecosystems; however, their presence was rarely documented in the participating communities and so is set aside for future work. There was one notable exception – a nitrogen-fixing bacterium. However, participants typically transpose this property onto the plants that provide conditions for that bacteria to grow – that is, they considered nitrogen fixation as though it was a property of the plant itself rather than of a bacterium that resides on the plant.