美国 南海岸植物园 South Coast Botanic Garden – 加州棕地绿洲植物园

从硅藻土矿坑到植物园：南海岸植物园的起源

南海岸植物园（South Coast Botanic Garden）位于加利福尼亚州洛杉矶县帕洛斯贝尔德斯丘陵，是世界上最早建在卫生填埋场之上的植物园之一。这片土地 1929 年到 1956 年曾被用作露天硅藻土矿坑，开采总量超过 100 万吨。1957 年矿场停产后，地块被卖给了洛杉矶县，先作为卫生填埋场使用到 1965 年；1961 年起，洛县议会批准了一项在当时颇具实验性的决议，把已覆土的矿坑改建成一座植物园。1961 年 4 月，第一批大规模种植在已封顶的填埋区展开，所用 4 万多株乔木、灌木全部由本地居民、苗圃和县植物园捐赠，废弃矿坑由此一步一步被改造成今日看到的园林。

87 英亩帕洛斯贝尔德斯丘陵：地理与基本格局

南海岸植物园占地约 87 英亩（约 35 公顷），地处洛杉矶县未建辖片区，属于南湾丘陵地貌的一部分，离洛杉矶国际机场以北约 16 公里。园区所在地原本是太平洋覆盖的区域，海中硅藻死后堆积形成的硅藻土就是当年被挖走的原料；填埋封场之后，地表高低不平，给园艺施工带来了不少难题。如今的园区按功能划分为入口广场、专类园区、自然林地与湖泊水系等几大区块，自西向东延伸，与南加州典型的干旱夏季气候相匹配。

20 万株植物与多主题专类园区

南海岸植物园以约 20 万株景观植物为骨架，包括加州沿海红杉（Coast Redwoods）、银杏、海桐属、开花果树，以及许多来自澳大利亚与南非的耐旱植物，覆盖大约 140 个科、700 个属、2000 多个物种。园内分为多个主题园区，常见的包括节水园区（Water-wise Garden）、香草园（Herb Garden）、英式玫瑰园（English Rose Garden）和感官园（Garden of the Senses）等。园区中部的小湖与溪流吸引了鸭子、鹅、白骨顶、苍鹭等多种水鸟；园区至今记录在案的鸟类超过 300 种，是南湾地区生物多样性较高的城市绿洲之一。

填埋场地基上的园艺挑战

南海岸植物园的园艺挑战在全球植物园里都属罕见。一是土壤几乎全是硅藻土，透水性强、保水性弱；二是填埋物料组成与厚度差异造成地面沉降速率不一，灌溉管线经常断裂；三是地下有机物分解会持续放热，并伴随二氧化碳与甲烷气体上升。因此园方不得不采用耐受干旱与高温的物种，许多外来植物必须先在小范围试验才能入大区栽种，这套边种边改的园艺方式，是在地下景观之上运营植物园的代价。

教育、会员与南加州公共绿地角色

南海岸植物园由洛杉矶县公园与游憩局与南海岸植物园基金会共同运营，主要收入来自门票、会员、捐赠与赞助。园方常年举办儿童、家庭、自然教育、艺术与节庆项目，并为周边社区提供园艺与志愿岗位；从露天矿坑到公共绿洲的转变本身就是面向公众的环境教育项目。作为洛杉矶县南湾少数被列入「棕地变绿洲」典型案例的公共植物园，它不仅是本地居民的游憩地，也是全美范围内「从过境矿坑走向公共绿地」的样本之一。

From a diatomite quarry to a botanic garden: The origins of South Coast Botanic Garden

South Coast Botanic Garden sits in the Palos Verdes Hills of unincorporated Los Angeles County, California, and is one of the world’s first botanic gardens developed over a sanitary landfill. The land was worked as an open-pit diatomite mine from 1929 to 1956, yielding more than one million tons of crude diatomite. After production fell off, the site was sold in 1957 to the County of Los Angeles, which used it as a sanitary landfill until 1965. In 1961 the County Board of Supervisors passed a motion to convert the already-capped portions of the site into a botanic garden. In April of that year the first major planting took place on the finished cap, using over 40,000 donated trees, shrubs, and other plants from local citizens, nurseries, and the County Arboretum — the start of the slow transformation of an old quarry into the landscape seen today.

The 87-acre Palos Verdes Hills: Setting and basic layout

The garden covers about 87 acres (around 35 hectares) in the Palos Verdes Hills of unincorporated LA County, about 10 miles (16 km) south of Los Angeles International Airport. Geologically the site began as seabed laid down by diatoms, and the diatomaceous earth that was mined out is exactly what the mine worked on. Once the surface was closed and capped, the resulting topography is uneven and rises gently inland from the Pacific, with views back across the LA Basin. Today the garden is divided into an entrance area, themed collections, native and naturalized planting zones, and a small lake and stream system running through its center.

Over 200,000 plants and the themed garden collections

South Coast Botanic Garden’s living plant collection numbers more than 200,000 plants from roughly 140 families, 700 genera, and 2,000 species, including Coast Redwoods, Ginkgos, Pittosporum, and flowering fruit trees. The garden is particularly strong on plants from Australia and South Africa. The garden is broken into a number of themed areas, including the Water-wise Garden, the Herb Garden, the English Rose Garden, and the Garden of the Senses. A small lake and stream bed attract ducks, geese, coots, and herons; more than 300 species of birds have been recorded on site, making the garden one of the more biodiverse urban oases on LA’s south bay.

Gardening on reclaimed landfill: unusual horticultural challenges

Horticulture at South Coast Botanic Garden presents unusual challenges for any botanical garden. First, the soil is almost entirely diatomaceous earth, which drains quickly and holds little water. Second, because the underlying fill varies in thickness and makeup, settling rates vary across the garden and the irrigation system has to be repaired and re-aligned on a regular basis. Third, heat is generated by decomposition of organic matter beneath the surface, accompanied by the release of gases, primarily carbon dioxide and methane. To cope, the garden relies heavily on drought-tolerant and heat-tolerant plants, pilots new introductions on small plots before planting them out, and accepts an ongoing program of repair and replanting as part of the cost of operating on reclaimed land. The lake is currently empty.

Education, programs, and the garden’s place in South LA’s public green spaces

South Coast Botanic Garden is operated jointly by the Los Angeles County Department of Parks and Recreation and the South Coast Botanic Garden Foundation, with income from admissions, memberships, donations, and corporate partnerships. The garden runs a year-round calendar of children’s, family, nature, arts, and seasonal events, and supports a large volunteer and docent program. The site, a former sanitary landfill capped and planted over more than six decades, is widely cited as a California case study in land recycling, and remains one of the few public botanic gardens in the LA Basin developed directly on a former landfill.

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