2020 ASLA RESEARCH AWARD OF HONOR: Seeding Specificity – Materials and Methods for Novel Ecoystems / Mahan Rykiel Associates

A thorough study of the planting process at Hart-Miller Island provides insight into how plants grow in new terrain

Project Specs

“该项目对马里兰州切萨皮克湾疏浚工程的产物——占地1140英亩的哈特-米勒岛——的种植过程进行了深入研究,为植物如何在新型土地环境中生长提供了资料。关于哪些种子能够在特定地点顺利存活的判断主要依赖于理想化的环境条件,而对哈特-米勒岛土地条件的观察显示,场地的特异性从很大程度上决定着植物的存活率。再进一步推断可以得出:仅仅依靠预期的种子发芽结果并不能充分地预测哪些植物能够生长;在实施种植计划之前,应当对所有新型土地环境进行类似的发芽研究。”
– 2020年评审委员会

“A thorough study of the planting process at 1,140-acre Hart-Miller Island—a product of dredging in Maryland’s Chesapeake Bay—provides insight into how plants grow in new terrain. Baseline knowledge about what seeds will thrive in a given location are based on idealized environments, and this look at the conditions on the ground at Hart-Miller Island reveals that site specificity plays a large role in determining planting success. Extrapolating this outward, the profession gains knowledge that simply relying upon expected seed germination outcomes will not adequately predict what grows, and that similar germination studies should be undertaken for any new ground prior to planting plan implementation.”
– 2020 Awards Jury

来自 ASLA 对gooood的分享。
Seeding Specificity: Materials and Methods for Novel Ecoystems | Mahan Rykiel Associates

 

项目陈述
PROJECT STATEMENT

景观设计师设计新的生态系统。这种动态的社会生态系统缺乏足够的自然对照物,而位于此类复杂场地中的项目往往会选择原始的、理想化的生态系统作为参考。本次研究探索了切萨皮克湾哈特-米勒岛(HMI)沉积物景观中的种子发芽率,拓宽了景观设计师在设计新型生态系统时所采用的材料和方法框架,具体的方法是对恢复策略和设计成果与实际项目的场地、土壤和植物物种的特征进行校正。研究结果显示,在受控条件下得出的发芽率与从实验中得出的发芽率存在着明显的差异,从而证明了将设计意图、研究方法和材料实践相结合的重要性。将实验结果转化为定制的种子组合以及恢复性项目的播种计划,能够加强景观研究方法和材料实践在设计中的应用;反过来又可以帮助景观设计师提高设计新生态系统和实现高性能成果的能力、巩固专业共同体并为充满活力的社会生态系统提供支持。

Landscape architects design novel ecosystems. These dynamic scoiecological environments lack adequate natural analogs, yet pristine, idealized ecosystems are often used as references for projects in these complex sites. This primary research exploring seed germination rates for the sediment landscape of Hart-Miller Island (HMI) in the Chesapeake Bay expands the material and methodological frameworks for landscape architects to design novel ecosystems by calibrating restoration strategies and design outcomes to the specificities of a real project site, soils, and plant species. The findings, which show significant variance between published germination rates under controlled conditions and experimentally derived seedling emergence in site soil, highlights the importance of aligning design intent, research methods, and material practices. The translation of the experimental findings into a custom seed mix and seeding plan for the restoration project reinforces the application of landscape research methods and material practices in design. These in turn, enhance the ability of landscape architects to design and realize high performance outcomes in novel ecosystems, strengthening the professional community and supporting vibrant socioecological systems.

▲参照场地v.s.项目场地:理想条件下的参照场地经常被用作某个具体项目场地的模型,但实际上二者的土壤、水文条件和生物地球化学条件均存在很大的差异,这可能会破坏设计意图和景观表现的结果。Reference Site v.s. Project Site: Idealized reference sites are often used as analogs for project sites who’s soil, hydrolgocial, and biogeochemical conditions vary dramatically, which can undermine design intent and landscape performance outcomes. © Mahan Rykiel Associates

 

项目说明
PROJECT NARRATIVE

哈特-米勒岛(HMI)位于美国马里兰州巴尔的摩县切萨皮克湾的上游,面积为1140英亩,是一个由哈特岛和米勒岛的残余物再造而成的新型生态系统——1984年至2009年期间使用了从巴尔的摩港航道疏浚的1亿立方码的泥沙。自2009年封岛以来,州政府机构一直致力于恢复该岛的生境,目的是为该州公民提供公共娱乐和享受自然资源的机会。然而,动态的场地条件使得800英亩的“North Cell”恢复工作变得复杂,包括断裂的水文系统、酸性硫酸盐土壤和外来物种(尤其是芦苇)带来的压力。本次研究详细描述了实地考察、恢复策略和基于实验而得出的发芽率,以便让团队使用这些成果来制定与设计意图、目标成果和场地现状相适宜的种子搭配方案和播种计划。

在意识到HMI的复杂性和自然模拟对照物的缺乏后,团队进了基础性的实地考察,记录并了解了项目场地特有的生物地球化学系统(biogeochemical systems),从而为设计具备成本效益和公众参与度的恢复策略提供有用的信息。实地考察的内容包括横断面研究,以及对样方(quadrat)的水位、土壤pH值、植被覆盖率和植物多样性的测量。每个场地的特征都有着明显的变化,被考察区域的水位在周期性淹没、持续淹没和静水位之间波动。土壤pH值为3-7,这是由疏浚沉积物构成的新型生态系统的一个共同特征,其原因是厌氧海洋矿物质在向有氧陆地环境转移的过程中会发生氧化反应,从而释放氢离子。植被的覆盖模式也有所不一,存在覆盖率达到100%的区域,也有覆盖率仅30%的区域。植物多样性仅限于9个常见于受干扰地区的属,其中以芦苇属最为普遍。

在为HMI的复杂环境制定恢复策略的过程中,项目团队了设计了一个“活体地形”,旨在对场地的地质水文条件进行分层,将芦苇从目标生境中分离出来,使植物群落结构多样化。修复设计中选用的物种主要参考了一些国家支持的研究和先例项目;选择的依据包括它们对土地条件变化的耐受度,以及在预设的“活体地形”中,综合群落从空间、功能和时间方面去填补生态位的能力。这其中也包括将物种与地上和地下结构配对、提供四季变化和演替轨迹的多样性,从而为场地赋予全年适宜的生境并支持复杂的新生生态环境。

为了实施为HMI制定的恢复计划,项目团队需要将概念性的植物搭配方案转化为定制的种子组合,然后将“目标幼苗/平方米”的期望数值和有效的播种密度传达给承包商。然而,在检视种子供应商公布的发芽率数据时,团队意识到该结果是从受控条件下的研究中得出的,与HMI的实际条件存在极大的差距。鉴于以上事实,研究小组启动了一个转化研究项目,将从HMI挖掘出来的土壤作为研究对象并观察幼苗在其中的萌发情况,从而因地制宜地对特定地点的播种方案进行校准。在推进这项研究时,团队以美国农业部、美国林务局以及植物保护联盟(Plant Conservation Alliance)为恢复和再利用项目制定的国家种子战略(National Seed Strategy)为依据,采用行业标准的方法进行本地种子的生产和培育。

在发芽研究的具体实验中,将“为恢复设计挑选的15个物种的官方公布发芽率”作为对照组,与“15个物种在项目场地的土壤中的发芽率”以及“15个物种在经过农用石灰处理的项目场地的土壤中的发芽率”进行对比。研究中使用的材料包括:

·装有可调节LED灯的生长塔
·6个72格的种植盘
·砂纸
·游戏用的沙子
·种子
·场地土壤/疏浚泥土
·农用石灰
·洒水壶
·pH值测试探针
·照相机

发芽研究中使用了三个基本方法:

一、土壤准备。研究所用的疏浚泥土是从考察区域内的三个随机地点收集而来。这些材料被带回实验室,在混合后被作为发芽实验的复合土壤样本,并对pH值加以记录。材料中的一半按照1:30的体积比例加入石灰,另一半不作处理。在准备好的6个72格种植盘中,其中3个装入经过石灰处理的疏浚泥土,另外3个装入未处理过的疏浚泥土。

二、种子准备。实验所需的种子均是根据行业标准条例来准备,能够准确地符合被研究植物物种的生长需要。准备的方法分为三种:刮擦、分层和直接播种。刮擦法是将种子铺在一张P150砂纸上,然后用P60砂纸于上方刮擦,直至5%-10%左右的种子被碾碎。分层法是按照1:3的比例将种子与潮湿的游戏用沙混合起来,然后根据每个物种的需要在冰箱中储存2-12周。直接播种法在播种前不对种子进行任何预先处理。当土壤和种子都准备完毕后,每个物种将占据36个种植格,其中18个格子里是经过加工的疏浚泥土,另外18个是未经加工的疏浚泥土。在每个格子中,每个物种的播种率是根据公布的休眠率而决定的,目标是每个格子成活一棵幼苗(例如,对于休眠率为80%的物种,每个格子内播撒5颗种子;休眠率为50%的物种,每个格子内播撒2颗种子,以此类推)。

三、数据收集。周一至周五,根据需要给每个格子浇水;生长灯设置为12小时的光照周期。周六至周日不进行浇水和照明。在整个研究期间,每周收集两次发芽数据,在数据表单中记录每个格子中可见的幼苗数量,并对幼苗拍照,以便记录种植盘中其他值得注意的进展(例如可能存在未播种的自发植物)。每两周,从6个72格的种植盘中随机选出3个格子进行pH值的记录。在经过6周的数据收集后,发芽研究结束,随后从每个物种中随机选出3棵幼苗并从格子中移出以收集根/芽数据。收集数据的过程包括浸透单元格,小心去除种植土壤并在水中清洗根部,最后将幼苗置于一张带有“土壤线”基准的数据表单上进行整体拍摄,以测量根/芽的长度。

研究结果显示,在受控条件下公布的发芽率与实验得出的场地土壤中的幼苗发芽率存在着显著的差异。项目团队利用实验得出的数据,提高了HMI恢复项目中拟定物种的播种效率。根据场地条件对种子的组合进行校准,能够确保恢复过程的准确性和有效性,并帮助试点项目中的生境建造进行更加精确的评估,这样就可以不再依赖理想化的数据,而是根据真实且类似的条件而得出更加准确的发芽率。

此项研究及其结果强调了将设计意图、研究方法和材料实践相结合的重要性。将实验结果转化为定制的种子组合以及恢复性项目的播种计划,能够加强景观研究方法和材料实践在设计中的应用;反过来又可以帮助景观设计师提高设计新生态系统和实现高性能成果的能力、巩固专业共同体并为充满活力的社会生态系统提供支持。

▲项目场地和环境:哈特-米勒岛(HMI)位于马里兰州巴尔的摩县切萨皮克湾上游,面积为1140英亩。它由巴尔的摩港航道疏浚的1亿立方码的泥沙构成,是一个新型的生态系统。Project Site & Context: Hart-Miller Island (HMI) is a 1,140 acre island located in the upper Chesapeake Bay in Baltimore County, Maryland. It is a novel ecosystem, built from the 100 million cubic yards of sediment dredged from Baltimore Harbor shipping channels. © Mahan Rykiel Associates

 

▲实地考察:由于缺乏足够的自然参照地,研究小组在HMI进行了基础性的实地考察,记录并了解了项目场地具体的生物地球化学系统,从而为恢复策略的制定提供信息依据。Field Research: Lacking an adequate natural analog reference site, the team conducted primary field research at HMI to document and understand the project site’s specific biogeochemical systems in order to inform the design of a restoration strategy. © Mahan Rykiel Associates

 

▲现有植物群落:研究区域的植物多样性仅限于9个常见于受干扰地区的属,其中以芦苇属最为普遍。Existing Plant Community: Plant diversity in the study area was limited to nine (9) genera commonly found in disturbed sites, with Phragmites as the the most prevelant genus encountered. © Mahan Rykiel Associates

 

▲恢复策略:在为HMI的复杂环境制定恢复策略时,团队设计了一个“活体地形”,旨在对该场地的地质水文进行分层,将芦苇从目标生境中分离,并使植物群落结构多样化。Restoration Strategy: In developing a restoration strategy for the complex conditions at HMI, the team designed a living landform intended to stratify the site’s geohydrology, grade separate Phragmites from targeted habitat areas, and diversify the plant community structure. © Mahan Rykiel Associates

 

▲种植设计:活体地形内的物种被组织为三种混合类型——喜湿植物、全能型植物和喜旱植物,这三类植物有着不同的耐受性,能够各自适应变化的土地条件(包括适度、pH值和通气压力)。Planting Design: Species for the living landforms were organized into three mix types – wet sepcialists, generalists, and dry sepcialists, and were selected for their individual tolerances to survive the documented variability of field conditions including moisture, pH, and invasive pressure. © Mahan Rykiel Associates

 

▲种植参照:恢复设计方案参考了国家支持的研究、先例项目和实地考察,旨在找到耐受性强的物种,以及能够在预设的“活体地形”中,从空间、功能和时间方面去填补生态位的综合群落。Planting References: The restoration design pallete drew on state sponsored studies, precedent projects, and field observations – aiming for individually tolerant species, as well as a composite community that could fill spatial, functional, and temporal niches in the proposed living landforms. © Mahan Rykiel Associates

 

▲发芽实验 – 材料和方法:为了实施HMI的恢复设计,项目团队需要将概念性的植物搭配方案转化为定制的种子组合,然后将“目标幼苗/平方米”的期望数值和有效的播种密度传达给承包商。Solving for Emergence: Materials and Methods. To implement the proposed restoration design for HMI, the team needed to convert the conceptual plant palette into a custom seed mix, which could be communicated to contractors via targeted seedlings/meter squared and effective seeding rates. © Mahan Rykiel Associates

 

▲发芽实验 – 记录和可视化:发芽研究包含四个主要步骤:土壤准备、种子准备、数据收集以及数据的可视化和解释。Solving for Emergence: Documentation and Visualization. The germination study included four primary steps: soil preparation, seed preparation, data collection, and data visualization and interpretation. © Mahan Rykiel Associates

 

▲研究结果样本页:研究结果显示,基于受控条件而公布的发芽率与在场地土壤、以及经过石灰处理的场地土壤中进行实验而得出的发芽率存在着显著的差异。Study Results Sample Page: Study findings showed significant variance between published germination rates under controlled conditions and experimentally derived seedling emergence in site soil and site soil amended with lime. © Mahan Rykiel Associates

 

▲结果 – 种子组合 I:喜湿植物。研究通过试验得出的发芽率为制定HMI恢复项目中拟定物种的有效播种率提供了缺失的变量。 Results: Seed Mix I – Wet Specialists. The experimentally derived germination rates from this study provide the missing variable in developing an effective seeding rate for the proposed species in the HMI restoration project. © Mahan Rykiel Associates

 

▲结果 – 种子组合 II:全能型植物。播种率的计算方法是用所需的每平方米的成活幼苗数除以实验得出的发芽率,从而得出每平方米的种子总数。Results: Seed Mix II – Generalists. The seeding rate is calculated by dividing the desired seedlings/㎡ by the experimentally derived germination rate to arrive at a total number of seeds/㎡. © Mahan Rykiel Associates

 

▲结果 – 种子组合 III:喜旱植物。根据已知种子的大小,每平方米的种子数量可被转换为每磅种子的数量,然后再得出每英亩种子的重量。这是一个行业标准的播种率,可在采购中被指定。Results: Seed Mix III – Dry Specialists. Once known, seeds/㎡ is converted to a quantity of seeds/pound based on known seed sizes, which is then converted to pounds of seed/acre – an industry standard seeding rate that can be specified for procurement. © Mahan Rykiel Associates

 

▲适应场地的种子组合:基于实验得出的比率,能够为HMI恢复项目制定有效的播种方案,保证种子组合能够准确而有效地适应场地的条件。Site Calibrated Seed Mix: Utilizing the experimentally derived rates to develop an effective seeding rate for the proposed species in the HMI restoration project ensures greater accuracy and efficacy in calibrating the seed mix to the site conditions. © Mahan Rykiel Associates

 

▲因地制宜的播种计划:将实验结果转化为定制的种子组合以及恢复性项目的播种计划,这一过程加强了景观研究方法和材料实践在设计中的应用。Site Specific Seeding Plan: The translation of the experimental findings into a custom seed mix and seeding plan for the HMI restoration project reinforces the application of landscape research methods and material practices in design. © Mahan Rykiel Associates

 

PROJECT NARRATIVE

Hart-Miller Island (HMI) is a 1,140 acre island located in the upper Chesapeake Bay in Baltimore County, Maryland. It is a novel ecosystem, built from the remnants of Hart Island and Miller Island using 100 million cubic yards of sediment dredged from Baltimore Harbor shipping channels between 1984 and 2009. Since its closure in 2009, state agencies have worked to restore the island habitat with the intent of providing public access recreation and natural resource enjoyment to the citizens of the state. However, restoration efforts in the 800 acre North Cell have been complicated by dynamic site conditions including a fractured hydrological regime, acid sulfate soils, and pressure from invasive species – notably Phragmites. This study details the field research, restoration strategy, and experimentally derived seedling emergence rates used by the team to develop a custom seed mix and seeding rate calibrated to the design intent, targeted outcomes, and existing conditions of the project site.

Recognizing the complexity of HMI and the lack of an adequate natural analog reference site, the team conducted primary field research to document and understand the project site’s specific biogeochemical systems in order to inform the design of a restoration strategy that would be cost-effective and publicly engaging. Field research included a transect study and measurements of water levels, soil pH, vegetative cover, and plant diversity in quadrats. Variability was notable for each of these site features with water levels in the study area fluctuating between periodically inundated, persistently inundated, and standing water. Soil pH ranged from as low as pH 3 to as high as pH 7 – a common feature of novel ecosystems constructed of dredged sediment, which are subject to oxidation reactions that release hydrogen ions during the translocation of anaerobic marine minerals to aerobic terrestrial environmental. Vegetative cover patterns were inconsistent showing areas of 100% cover and areas of 30% cover. Plant diversity was limited to nine (9) genera commonly found in disturbed sites, with Phragmites as the the most prevalent genus encountered.

In developing a restoration strategy for the complex conditions at HMI, the team designed a living landform intended to stratify the site’s geohydrology, grade separate Phragmites from targeted habitat areas, and diversify the plant community structure. Species for this restoration design drew on state sponsored studies and precedent projects, and were selected for their individual tolerances to survive the documented variability of field conditions, as well as the capabilities of the composite community to fill spatial, functional, and temporal niches in the proposed living landforms. This included pairing species with complimentary above ground and below ground structures, as well as providing diversity in seasonality and successional trajectories to offer year round habitat opportunities and to support complex emergent ecologies.

To implement the proposed restoration design for HMI, the team needed to convert the conceptual plant palette into a custom seed mix, which could be communicated to contractors via targeted seedlings/meter squared and effective seeding rates. However, in reviewing published germination rates provided by seed vendors, the team realized that they were derived from studies in controlled conditions, which diverge dramatically from the existing conditions at HMI. Recognizing this data gap, the team initiated a translational research project to study seedling emergence in soils excavated from HMI to calibrate a site specific seeding plan to the actual conditions of the island. In pursuing this research, the team deployed industry standard methodologies for native seed production and propagation based on guidance from the United States Department of Agriculture, the United States Forest Service , and the Plant Conservation Alliance National Seed Strategy for Rehabilitation and Restoration.

The experimental design of the germination study compared published germination rates of the 15 species selected for the restoration design as a control with seedling emergence of the 15 selected species in soil collected from the project site, and with seedling emergence of the 15 selected species in soil collected from the project site treated with agricultural lime. Materials utilized in the germination study included:

• Grow tower with adjustable LED lights
• Six 72-cell growing trays
• Sandpaper
• Play sand
• Seeds
• Site soil/dredged material
• Agricultural lime
• Watering can
• pH test probe
• Camera

Three primary methods were used in the germination study including:

• Soil Preparation: Dredged material for the germination study was collected from three random locations within the study area. The material was brought back to the lab and blended to create one composite soil sample for the germination trials and pH was documented. Half of the material was amended with lime at a 1:30 ratio by volume and half was left unamended. Three 72-cell trays were filled with the amended dredged material and three 72-cell trays were filled with unamended dredged material

• Seed Preparation: Seeds were prepared for the germination trials using industry standard protocols, which are tailored to the needs of the specific plant species under investigation. The three preparation methods were scarification, stratification, and direct seeding. The scarification method included laying seeds on a sheet of P150 sandpaper and scraping over the top with P60 sandpaper until approximately 5%-10% of seeds are visible crushed. The stratification method included mixing seeds at a ratio of 1:3 with damp play sand and then storing in a refrigerator for 2-12 weeks as needed for each species. The direct seeding method included no pre-treatment of seeds prior to planting. After soil and seed preparation 18 cells of each species were seeded in amended and unamended dredged material (for a total of 36 cells of each species). Seeding rates for each species in a cell were based on published dormancy percentages with the aim of one live seedling/cell (e.g. for species with an 80% dormancy rate, the cell was planted with five seeds; and for species with 50% dormancy rate, the cell was planted with two seeds, etc.).

• Data Collection: Cells were watered daily as needed Monday-Friday. Grow lights were set for a 12 hour photoperiod of light/dark Monday-Friday. Watering and lighting did not occur Saturday-Sunday. Germination data was collected twice weekly throughout the duration of the study. This included recording the number of visible seedlings in each cell on a data sheet and photographing the seedlings, as well as documenting other notable developments in the trays (e.g. presence of non-seeded volunteer species.). Every two weeks pH was recorded from three randomly selected cells in each of the six 72-cell trays. After six weeks of data collection, the germination study was closed and three randomly selected seedlings from each species were removed from the cells to collect root/shoot data. This included saturating the cells, gently removing plant material, washing roots in water, and photographing the entire plant position on a data sheet with a ‘soil line’ datum to measure root/shoot length.

Study findings showed significant variance between published germination rates under controlled conditions and experimentally derived seedling emergence in site soil. The team utilized the experimentally derived rates to develop an effective seeding rate for the proposed species in the HMI restoration project. Calibrating the seed mix to the site conditions ensures greater accuracy and efficacy for restoration and supports a more accurate assessment of habitat establishment in the pilot project, which can be evaluated not based on an idealized published germination rate, but rather an experimentally derived germination rate from a truly analogous condition.

This study and its results highlight the importance of aligning design intent, research methods, and material practices. The translation of the experimental findings into a custom seed mix and seeding plan for the restoration project reinforces the application of landscape research methods and material practices in design. These in turn, enhance the ability of landscape architects to design and realize high performance outcomes in novel ecosystems, strengthening the professional community and supporting vibrant socioecological systems.

More:ASLAMahan Rykiel Associates

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