Ecological Designed Experiment Method Based on Pragmatism: A Case Study of Haizhu Wetland Restoration Project in Guangzhou, China

Abstract

Exploring the effect ecological design methods is a critical issue for sustainable development, yet a gap still exists between the research and practices of ecological landscape design. This study employed pragmatic designed experiments as its core method, integrating methodologies from empiricism, positivism, and romanticism to propose a semi-empirical ecological design framework that emphasizes learning by doing and research through practice. The framework encompasses three steps: prototyping, designed experiments, and monitoring and adjustment. The study further took the restoration project of Haizhu Wetland in Guangzhou as an example by proposing five designed experiments based on the analysis of form prototypes suitable for the site: the mound-based orchard wetland system, enhanced paddy field system, bird island, high-tide habitat, and a low-maintenance resilient water system. Corresponding design hypotheses and monitoring and adjustment evaluation indicators were also offered. The results showcase the feasibility of integrating ecological research with practical application to steer ecological design optimization and enhance the resilience of anthropogenic ecosystems. Although the wetland renovation project has initially shown ecological benefits and social welfare, the effectiveness of this design framework still requires further tracking and validation.

● Constructs a learning-by-doing and semi-empirical ecological design framework based on pragmatism to facilitate effective learning through practices

● The ecological design framework includes three main steps of prototyping, designed experiment, and monitoring and adjustment

● Enhances the analytical capabilities regarding ecological knowledge and prototypes and establishes routines of monitoring and assessing the effectiveness of ecological design, thus increasing the flexibility of design process

Graphical abstract

Keywords

Novel Ecosystem / Urban Wetlands / Pragmatism / Design Prototype / Designed Experiment / Monitoring and Adjustment

1 Introduction

The advancement of urbanization and globalization has impacted every corner of the Earth, ushering in a new era known as the Anthropocene^[1][2]. Presently, human activities have transformed over one-third of the planet's ecosystems, including agricultural lands and urban areas^[3]. Each year, nearly half of the biological productivity of terrestrial ecosystems^[4] and renewable freshwater resources^[5] are consumed by humans, which is altering the global biogeochemical cycle^[6]. This has led to the emergence of novel ecosystems in the Anthropocene, characterized by human influence and exhibiting three characteristics: 1) they surpass natural ecological thresholds; 2) their species composition significantly diverges from natural ecosystems; and 3) they have established self-sustaining mechanisms^[7][8]. Despite their widespread presence, these systems often exhibit conflicts between their social and natural functions due to the short evolutionary history. Without balancing these dual functions, the planet may suffer extensive adverse effects. Thus, there is an urgent need to define and achieve the equilibrium of novel ecosystems.

Since the 1970s, the global academic community has embarked on exploring modern ecological design methods^[9], while China initiated the exploration into urban and landscape ecological design at the onset of the 21st century^[10][11]. Despite the rapid development of modern ecology, marked by the rise of Landscape Ecology and Global Ecology at the macro scale, and a focus on organs, cells, organelles, and molecules at the micro scale^[12], a persistent gap exists between ecological research and landscape design practices^[2]~[5]. The concepts of ecological design have largely remained theoretical, lacking practical application and thus falling short in guiding formative design^[12].

This gap can be primarily attributed to two aspects. Firstly, the deconstructive nature of modern ecological research does not align with the holistic nature of ecological practices^[13]. Secondly, ecological practices encompass subjective processes that cannot be fully explained by the purely rational paradigm of modern ecological research. Landscape architects should employ the improvisation ability, which is rooted in irrationality, imagination, and mystique^[14], to integrate fragmented, abstruse, and generalized scientific findings with specific demands, thereby realizing those findings in spatial forms. Consequently, this study seeks to diverge from the mainstream scientific positivism methodology and take pragmatic designed experiments as the main framework, while combining the technical methods of empiricism, positivism, and romanticism. This practical ecological design approach was proposed to enhance ecosystem resilience, exemplified through the Haizhu Wetland restoration project in Guangzhou, China led by the authors' team.

2 Pragmatic Ecological Designed Experiment

Broadly speaking, ecological design refers to purposeful manipulation of the structure and function of ecosystems to meet predetermined goals^[2]. These designed ecosystems mark a deliberate shaping of the Anthropocene ecosystems, distinguished by human-directed management and interventions^[15]. When contrasting these two types of ecosystems (Fig.1)^[8], the former emerges from intensive human intervention, necessitating ongoing maintenance and management, while the latter does not need; the former is purpose-built and caters to explicit human needs, while the latter is shaped by unconscious human activities. However, the designed ecosystems cannot replicate the untouched state of natural ecosystems, considering existing human desires, environmental conditions, and level of knowledge and technology. Instead, they incorporate human influences as inherent components, optimizing ecosystem services within coupled nature-human ecosystems, steering clear an idealized return to unspoiled nature^[16]. Across both urban and rural contexts, the optimized ecosystem services are pivotal in bolstering ecosystem resilience^[17]~[19].

Fig.1 Transformation between different types of ecosystems (adapted from: Ref. [8]).

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Such designed ecosystems demand a novel pragmatic paradigm that fuses design with science, elevating the role of design with ecological sciences and positioning landscape architects as key contributors to research^[20]. Derived from diverse philosophical underpinnings, present-day ecological design is developed based on methodologies including positivism, empiricism, pragmatism, and romanticism (Tab.1)^[9]. Among them, the "adaptation" concept of pragmatism advocates for learning by doing, which involves multiple experimental scheme implementation, scale control of individual experiments, and monitoring and adjustment for ecological design. On this basis, this study proposes a pragmatism-centered comprehensive framework that unfolds through prototyping, designed experiment, and monitoring and adjustment, combining different ecological design methods and stakeholders together (Fig.2).

Tab.1 Comparison of ecological design approaches based on different methodological foundations

	Positivism	Empiricism	Pragmatism	Romanticism
Ecological view	Equilibrium paradigm	Equilibrium paradigm	Complexity paradigm	Open ecological view
	Complexity paradigm	Complexity paradigm	Anthropocene ecosystem
Methodology	Scientific deduction	Empirical induction	Dialectic	Artistic abstraction
			Practical retroductive	Philosophical speculation
Starting point	Ecology (main)	Ecological ethics (main)	Ecological ethics	Ecological aesthetics
	Ecological ethics (secondary)	Ecology (secondary)	Ecology	Ecological ethics
Typical topic	Ecosystems, landscape ecology, urban ecology, modeling and assessment, etc.	Ecological wisdom, ecological practical wisdom, local knowledge, vernacular landscape, cultural landscape, etc.	Adaptive planning, designed experiment, designed ecology, public participation, social equity, etc.	Land art, ecological aesthetics, environmental perception, environmental education, etc.

Fig.2 Framework of ecological design based on pragmatism.

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2.1 Prototyping

The initial step in ecological design involves selecting form prototypes that resonate with ecological significance for subsequent designed experiments. Ecological significance here implies forms that deliver tangible ecological benefits or convey beneficial ecological notions, or both.

Form prototypes that offer tangible ecological benefits can be derived from positivistic design simulations and empirical design collaborations. Design simulation leverages ecological knowledge to forecast the functional outcomes of specific design forms, employing methods such as computational tools. Through variable parameter settings, this process spawns diverse design prototypes, evaluates their ecological performance, and identifies suitable form prototypes. Examples include parametric design and performative design for small- and medium-scale sites^[21][22], and scenario analysis for large-scale landscapes^[23][24]. Such simulations enable the visualization of ecological functions on three-dimensional site models, fostering a meaningful dialogue between landscape architects and ecologists. Concurrently, the indigenous practices reflective of local knowledge offer invaluable insights^[13][25][26]. The local knowledge, born from the deep-rooted interaction between communities and their environments over generations, embodies a repository of ecological wisdom, even though such empirical indigenous practices may not always adhere to scientific, precise standards^[27]~[29]. Through collaborative efforts, landscape architects can assimilate local knowledge, translating it into form prototypes. These two approaches can blend universal knowledge with indigenous insights, enriching landscape architects' grasp of the local ecological culture, consciousness, current conditions, and basic data.

Form prototypes capable of conveying beneficial ecological notions can be extracted from romanticism design collaboration. This philosophy emphasizes conveying ecological consciousness and inspiring public ecological aesthetics and contemplation through artistic endeavors, rather than addressing specific environmental problems directly^[30]. Through collaboration with artists and the public, landscape architects can craft formative expressions that enhance public perception and understanding on ecological processes and environmental issues to provoke environmental reflection and awareness, thus serving as a conduit for environmental experience and education.

2.2 Designed Experiment

Designed experiment frames design projects as repeatable ecological experimental units, aiming to validate ecological hypotheses while achieving functional and aesthetic goals^[31][32]. This method has been applied to forefront topics such as climate adaptation^[33], biodiversity enhancement^[34], and Nature-based Solutions^[35]. The implementation strategy primarily involves three steps: 1) translating abstract knowledge into tangible form prototypes to achieve specific functions; 2) fine-tuning the parameters of a given form prototype to optimize its functionality; 3) integrating various form prototypes to realize multifaceted functions. Designed experiment relies on landscape architects' subjective judgment, rather than specific ecological knowledge^①, to refine prototypes, necessitating the formulation of design hypotheses and post-construction evaluation frameworks. This iterative process of hypothesis validation and form refinement, known as "retroductive"^[36], gradually leads to the development of rational and effective design solutions.

① The essence of this process blends empiricism with a stronger inclination towards pragmatism. The difference of these two methodologies lies in whether there is sufficient argumentation beforehand. Empiricism is grounded in observable facts, while pragmatism depends more on subjective judgement. Whether it is about transforming abstract and profound knowledge into specific forms or integrating diverse prototypes, landscape architects usually lack direct empirical evidence, relying more on subjective inference, which is in line with the "trial and error correction" feature of pragmatism.

Designed experiment is an ecological experiment with hypotheses^[37], inherently embracing the possibility of failure. To manage this risk and enhance outcome predictability, certain principles should be adhered to: 1) full-cycle involvement—in addition to early consultation and post-construction evaluation, researchers should engage throughout the design process, especially in formulating design hypotheses and post-construction evaluation methods^[38]; 2) multifaceted objectives—designed experiments should consider various goals, including urban functionality, human engagement, ecological benefits, and aesthetics^[31], to ensure partial success even if not all objectives are met; 3) safe to fail—experiments should be conducted at scales where potential negative outcomes are manageable, thus not jeopardizing the broader ecosystem and habitats^[37]; 4) adaptability—designed experiments are innovative and iterative processes, for which even proven design solutions may require adjustments when applied in new contexts^[39].

2.3 Monitoring and Adjustment

The monitoring and adjustment phase is pivotal for the continuous optimization of design forms, acting as the foundation for effective ecosystem design and management^[40]. This phase involves the collection and analysis of primary data against the preestablished evaluation criteria to test hypotheses and summarize outcomes, both successful and unsuccessful. These insights inform immediate adjustments in design masterplan, form, materials, or will be applied to future design. The evaluation methods should be tailored to the specific site and design challenges, with options ranging from green energy metrics like the Leadership in Energy and Environmental Design (LEED) and Building Performance Evaluation, to sustainability benchmarks like the Landscape Performance Series, Post Occupancy Evaluation, and Sustainable Sites Initiative, and ecological restoration indices such as the National Ecological Observatory Network and National River Restoration Science Synthesis project.

Monitoring and tracking extends beyond immediate outcomes, assessing the enduring impact of ecological designs. Previous evaluation methods often lack this long-term perspective, focusing on single-time snapshots of landscape performance^[41]. Today, leveraging advancements in big data and the Internet of Things (IoT), researchers are increasingly capable of conducting extended monitoring and assessment^[42]~[44]. Establishing ongoing collaborations with site stakeholders, including local governments, operating companies or management organizations, and residents, can enhance the feasibility of sustained, high-frequency monitoring. This may involve integrating evaluation-related data collection into routine operations, installing monitoring sensors with management approval, or scheduling regular site visits to gather longitudinal data.

3 Ecological Designed Experiment for Haizhu Wetland

3.1 Research Area

Haizhu Wetland, located in the central urban area of Guangzhou, covers an area of 1,100 hm² (Fig.3). It epitomizes an Anthropocene ecosystem, where natural and artificial elements converge, including the natural tidal river network of the Pearl River Delta, Lingnan area's traditional agricultural system, recreational parks, water management and storage infrastructures, and the scientific research and education system. In 2019, the launch of the Guangzhou Haizhu Wetland Biodiversity Conservation and Restoration Project marked a significant step towards creating an urban central life community, along with objectives to foster diverse river networks, productive wetlands, minimal-intervention habitats, complete ecological cycles, and enduring societal support. This project is a venture into designing coupled nature-human ecosystems for multiple goals.

Fig.3 Distribution of the 5 designed experiments.

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The project navigates through multiple restoration goals and an intricate process, with existing ecological knowledge falling short of meeting the design demands. Therefore, a pragmatic ecological design method was adopted for the designed experiments. Aligning with the four foundational principles of designed experiments, the project devised the following specific strategies. 1) Multi-stakeholder engagement throughout the whole process: this involved collaboration with landscape architects, researchers, and local residents from the outset, such as consulting with the Institute of Zoology, Guangdong Academy of Sciences for expert zoological insights and monitoring frameworks for performance assessment, and incorporating local agricultural wisdoms shared by local residents. 2) Multiple objectives: this included enhancing urban stormwater storage and flood control, restoring habitats for key species, preserving agricultural heritage, and enriching public activities. 3) Acceptable experimental scale: only a 146-hectare portion of the wetland was designated for experimental interventions to minimize the risk of irreversible damage to the overall ecosystem. 4) Adaptive adjustment: while drawing from biodiversity restoration techniques and traditional Lingnan agricultural practices, the project remained open to novel design methods that resonate with the site's unique context and the social and demographic backdrop, venturing beyond tried and tested models.

3.2 Prototyping

The form prototypes of this project are derived from three distinct sources (Tab.2).

Tab.2 Overview of the design prototypes

Methodological basis	Prototype No.	Prototype name
Empiricism	1	Mound-based orchard
	2	Traditional vegetable paddy field
	3	Orchard tidal channel composting technique
Positivism	4	Bird habitat	Bird island
	5		High-tide habitat
	6		Four-season orchard
	7	Fish habitat	Fishway
	8		Natural embankment
	9		Micro-wetland cluster
	10	Insect habitat	Insect house
	11	Water purification system	Purification measures for Class Ⅲ water bodies
Romanticism	12	Lingnan water town complex
	13	Lingnan fine fruit complex
	14	Other local complex

1) Empiricism prototype. Inspired by local agricultural heritage, this project introduced the mound-based (duoji) orchard, a practice with roots in the Qin and Han dynasties and reaching its zenith in the Ming and Qing dynasties. This system, foundational to the Haizhu Wetland, combines wide mounds (8 ~ 10 m in width) for orchard planting and narrow orchard tidal channels, leveraging the tidal river network to sustain the agricultural ecosystem with nutrients and transport. Despite its historical significance, this prototype is primarily geared towards agricultural productivity with limited functional diversity.

2) Positivism prototype. Grounded in the ecological principles outlined in the General Plan for Wetland Restoration of Guangzhou Haizhu National Wetland Park, as well as insights into the behaviors of waterbirds, insects, and aquatic animals from Institute of Zoology, Guangdong Academy of Sciences, this project envisioned a variety of habitat scenarios, including natural embankment, bird islands, fishways, high-tide habitats, and micro-wetland clusters. However, these prototypes remain untested in practice, with their physical forms and functional efficacy pending further exploration.

3) Romanticism prototype. The project was inspired by the deep connection local residents have with their environment, particularly the affinity for the Lingnan water town complex (distinguished water town heritage) and Lingnan fine fruit complex (distinguished fruit heritage). The Lingnan water town complex reflects a lifestyle and traditions that revolve around the waterways of the Pearl River Delta, including water-based living and travel, and dragon boat celebrations. The Lingnan fine fruit complex stems from the tradition of cultivating premium fruits such as longan (Dimocarpus longan), lychee (Litchi chinensis), and yangtao (Averrhoa carambola), which were historically exported abroad. However, escalating land values and deteriorating water quality have gradually eroded the agricultural viability of the Haizhu Wetland and its associated cultural practices, with a communal aspiration to restore its historical splendor.

3.3 Designed Experiment and Monitoring Plan

To achieve the five sub-goals while considering the specific conditions of each plot, this project combined form prototypes with different ecological effects to ultimately establish 5 designed experiments (Tab.3, Fig.3). These experiments include moundbased orchard wetland system, enhanced paddy field system, bird island, high-tide habitat, and low-maintenance resilient water system, aiming to realize the compound socio-ecological functions.

Tab.3 Overview of designed experiments in Haizhu Wetland

Experiment type	Morphological design approach		Design hypothesis		Monitoring indicator
	Prototype integration	Prototype realization	Improvement	New vision
Mound-based orchard wetland system	1 Mound-based orchard6 Four-season orchard8 Natural embankment9 Micro-wetland cluster13 Lingnan fine fruit complex	—	· Preserving agricultural heritage	· Constructing a complete biologic chain· Enhancing stormwater retention capacity	· The growth of existing fruit trees· Diversity enhancement of aquatic plants and animals, birds, and insects· Forest birds' foraging conditions· Stormwater retention capacity
Enhancedpaddy field system	3 Traditional vegetable paddy field7 Fishway12 Lingnan water town complex	—	· Reconnecting people with the land	· Increasing habitat for aquatic animals· Providing food sources for various species· Improving stormwater retention capacity of the wetland	· Diversity enhancement of aquatic plants and animals, birds, and insects· Forest birds' foraging conditions· Stormwater retention capacity· Co-construction and maintenance proportion
Bird island	—	4 Bird island	—	· Providing nesting, breeding, and nearby foraging places for large waterbirds	· Nesting density and quantity of waterbirds· Species and ratios of nesting waterbirds· Usage intensity and time distribution of various waterbirds for foraging on shallow beaches, wooden stakes, and rafts
High-tide habitat	—	5 High-tide habitat	—	· Offering foraging and resting areas for waterbirds unaffected by tides	· Usage intensity and time distribution of various waterbirds for deep and shallow water areas· Usage intensity and time distribution of various waterbirds for sandstone embankments
Low-maintenance resilient water system	1 Mound-based orchard3 Orchard tidal channel composting technique11 Purification measures for Class Ⅲ water bodies12 Lingnan water town complex	—	· Reducing maintenance costs of water systems· Improving wetland water quality	· Preserving dragon boat culture	· Annual maintenance cost· Water quality monitoring data comparison· Annual dragon boat cultural activities

NOTE"Prototype integration" means to create new forms by integrating or modifying existing prototypes with physical forms; "prototype realization" means to form specific design forms based on the functional requirements of theoretical prototypes without concrete shapes.

3.3.1 Mound-based Orchard Wetland System by Integrating Local Knowledge and Ecological Theoretical Wisdom

The mound-based orchard wetland system integrates prototypes of mound-based orchard under empiricism, the positivistic bird and fish habitat construction, and the romanticism-inspired Lingnan fine fruit complex. Following the mound-based orchard wetland theory and construction techniques proposed by Xingzhong Yuan et al.^[45], this project utilized tidal actions for low-maintenance energy supplementation and orchard production. It transformed the originally steep orchard embankments into natural ones with winding, gentle slopes entering the water, while sculpting the aquatic bed into a habitat-rich landscape for aquatic species to lay eggs, hide, and forage. In addition to preserving the existing trees in the orchard, 54 species of fruit trees were introduced, establishing a year-round food oasis with fruits and nectar, complemented by strategically placed insect houses to complete the ecological chain (Fig.4).

Fig.4 The orchard before restoration (left) and the mound-based orchard wetland system (right) designed to create natural embankment, modify underwater topography, increase tree species that can provide food, and construct a complete food chain.

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Design of the mound-based orchard wetland system planned to achieve the following 5 goals. 1) The growth of existing fruit trees in the site should maintained despite topography and hydrology modifications, thus to preserve agricultural heritage. 2) The transformation of underwater topography can effectively enrich aquatic animal species. 3) The introduction of tree species that provide fruits and nectar throughout the year can attract omnivorous songbirds such as Pycnonotus jocosus, Zosterops japonicus, and Pycnonotus aurigaster, which feed on plant fruits, seeds, and insects^[46]. 4) An increase of insect population will attract insectivorous songbirds like Lanius schach, Phoenicurus auroreus, and Parus major^[46]. 5) The wetland's capacity of stormwater storage and flood control can be enhanced by widening the orchard tidal channels.

In the monitoring and adjustment phase, the project established 4 assessments to reflect the above goals. 1) Compare fruit tree growth data annually, collected by multispectral drones and agricultural records from farmers, with the data from the year following project completion. This evaluation categorizes the fruit trees into three states of growth—unchanged, improved, and declined, based on which the proportion and spatial distribution of each state will be analyzed to assess whether the original fruits and vegetables can thrive in the newly created wetland. 2) Every five years, a specialized zoological team will perform detailed surveys to measure and compare the diversity of aquatic fauna and flora, birds, and insects. 3) Analyze annually the relationship between traditional and newly introduced tree species and their impact on the foraging patterns of forest birds, using data from fixed observation equipment placed in the wetland and the birdwatching groups. 4) Calculate the variance in water storage capacity between the original and transformed water systems, based on the asbuilt drawings to assess improvements in stormwater and flood management.

3.3.2 Enhanced Paddy Field System by Integrating Local Knowledge and Ecological Theoretical Wisdom

The enhanced paddy field system combines prototypes of the empiricism-based traditional vegetable paddy field, the positivistic fishway, and the romanticism-inspired Lingnan water town complex, aiming to increase the habitat for aquatic animals and provide food sources for other animals like birds. Unlike traditional vegetable paddy fields, which were primarily for crop production with paths crisscrossing the fields, the enhanced ones can improve wetland resilience by substituting these paths with serpentine fishways ranging from 0.5 ~ 1.5 m in depth (Fig.5). Connected to the Pearl River and leveraging its tidal influences, these fishways can draw in local aquatic species such as fish, shrimp, eels, loaches, snails, frogs, and crabs. This approach enables species traditionally confined to orchard tidal channels to migrate, forage, and hide from predators in these designed fishways. Between these fishways, wild and cultivated rice varieties are planted to serve as the primary carbohydrate source for birds, aquatic animals, and insects^[46]. The system's management employs a community engagement strategy, enlisting local residents to guide volunteers and students in environmental education programs for the sowing and harvesting of rice (Fig.6).

Fig.5 The enhanced paddy field system: from paths in field to fishways.

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Fig.6 The enhanced paddy field system coconstructed by the public becomes a paradise for wildlife.

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There are 4 design hypotheses for the enhanced paddy field system. 1) The paddy fields and fishways should attract birds for foraging, including wading birds such as Egretta garzetta, Nycticorax nycticorax, Ardea cinerea, Amaurornis phoenicurus, and Gallinula chloropus; swimming birds such as Anas zonorhyncha and Tachybaptus ruficollis; as well as songbirds like Lonchura punctulata^[46][47]. 2) Increase habitats for fish and other aquatic animals to enrich the populations of native aquatic communities and benthos. 3) Construction of fishways in the paddy fields can connect to the river system, enhancing the wetland's capacity for stormwater and flood management. 4) Establish a sustainable community-involved cultivation and maintenance of paddy fields, thereby reconnecting people with the land.

In the monitoring and adjustment phase, an extra assessment in addition to those established for the mound-based orchard wetland system is the annual proportion assessment of the coconstruction and maintenance paddy field area to the total paddy field area. This evaluation categorizes results into three levels of co-construction and maintenance sustainability: (90%, 100%] as excellent, (80%, 90%] as average, and [0, 80%] as limited^②.

② For participatory sites, the degree of landscape maintenance visible to the public directly impacts public participation. Drawing from past agricultural projects, the design team held that public participation will decrease when over 20% of the paddy fields are abandoned, as the agricultural landscape begins to appear neglected. Therefore, this study empirically set 80% and below as limited co-construction and maintenance sustainability, with further classification into "excellent" and "average" within this sustainable range.

3.3.3 Bird Island Through Spatial Realization of an Ecological Theoretical Prototype

Bird island is a form prototype designed entirely grounded in the positivistic ecological principles. Ornithologists involved in the project identified 4 key functions of the island for waterbirds: nesting, foraging, perching, and roosting. Based on these functions, 5 strategies were proposed for the form design (Fig.7, Fig.8).

Fig.7 The bird island before restoration and strategies to meet the nesting, breeding, and foraging needs of waterbirds.

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Fig.8 The bird island transforms the previous tourist island into a sound habitat for waterbirds.

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1) Increase the number and density of tree species that favor large waterbird nesting on the island, such as Ficus concinna, Ficus benjamina, and Broussonetia papyrifera. These species were chosen for their dense foliage, structural support, non-toxicity, and low predator attraction. 2) Create uneven foraging shallows along the perimeter of the island. At high tide, these shallows are submerged to a depth of 10 ~ 30 cm, ideal for waterbirds to forage while standing; at low tide, the shallows form flats, providing spots for waterbirds to stand, observe, and forage opportunistically. Edges of the shallows extend into the water, forming small bays for distinct standing territories of different waterbirds. 3) Install wooden stakes in the deeper surrounding area of the island, with pine stakes driven into the water and dead tree stumps from orchards placed randomly, providing perching spots for waterbirds. 4) Place floating rafts planted with hygrophytes around the island to mimic natural waterbird roosting sites.

Three design hypotheses were set for the bird island. 1) The nesting forests are expected to attract wading bird communities such as Egretta garzetta, Ardea cinerea, Nycticorax nycticorax, and Phalacrocorax carbo for nesting and breeding. 2) The shallows and wooden stakes can attract wading bird communities including Egretta garzetta, Ardea cinerea, Nycticorax nycticorax, Phalacrocorax carbo, Amaurornis phoenicurus, and Gallinula chloropus for foraging and resting. 3) The floating rafts can attract swimming birds like Anas zonorhyncha and Tachybaptus ruficollis, as well as the aforementioned wading bird communities for habitation.^[46]

For monitoring and adjustment, the bird island has been equipped with monitoring devices to collect video and audio around its perimeter and inside. This enables the analysis of nesting density and quantity of waterbirds, their species diversity and proportion, and their usage intensity and time distribution of shallows, wooden stakes, and floating rafts, with the information extracted from the monitor data through image and audio recognition technologies.

3.3.4 High-tide Habitat Through Spatial Realization of an Ecological Theoretical Prototype

Similarly, the high-tide habitat is also rooted in positivistic ecological principles. The theory of high-tide habitats proposed by the ornithologists suggests that when rivers flood the tidal flat during high tide, they provide sites for waterbirds to forage in shallow water and rest along riverbanks. The theory requires creating a habitat that is at least 12 m in width and 50 m in length, ensuring ample space for group takeoffs and landings. Moreover, a low sand embankment should be set at the center of the water area, providing a rest area for waterbirds free from tall vegetation that may block views of potential predators. Water levels should also be carefully managed to a certain depth to maintain a nutrient-rich environment for waterbirds. Considering all these principles, this project designed a 158-meter long sand and stone embankments and a high-tide habitat with three takeoff and landing water surfaces. The water level can be regulated by a passive sluice, allowing the depth to gently increase from the center of the embankments outward, catering to the diverse preferences of various waterbird species (Fig.9). The upstream of this area is connected to the mound-based orchard wetland system through the sluice, ensuring an adequate food supply.

Fig.9 Habitat site before restoration (left) and the high-tide habitat (right) meeting the takeoff and foraging needs of waterbirds with different wingspans and leg lengths.

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Design hypotheses for the high-tide habitat includes attracting wading birds like Egretta garzetta, Ardea cinerea, Nycticorax nycticorax, Phalacrocorax carbo, Amaurornis phoenicurus, and Gallinula chloropus, as well as swimming birds such as Anas zonorhyncha and Tachybaptus ruficollis to rest and forage during high tide^[46].

For monitoring and adjustment, devices similar to those used on the bird island were installed to assess the usage intensity and time distribution of various waterbirds in both shallow and deep water areas as well as on sand embankment.

3.3.5 Low-Maintenance Resilient Water System—Integrating Novel and Traditional Technologies to Sustain Cultural Complex

By merging the empirical orchard tidal channel composting technique, positivistic water purification measures, and the romantic Lingnan water town complex, a self-purifying three-level system of wetland water network is established, consisting of a main channel, connected branch channels, and dredged orchard tidal channels. This system also serves as a critical site for dragon boat storage. The mud composting process involves layering silt from the river network atop the mound surface, facilitating dredging of the water system and soil fertilization. Employing local residents adept in this technique, this project revitalized the three-level water network and reconnected thousands of capillarylike orchard tidal channels (Fig.10). The area and length of the water system were also increased, incorporating water purification measures, including permeable filtration, plant purification, and algae-eating insect introduction to continuously improve wetland water quality with low maintenance costs (Fig.11). Moreover, the system conserves a traditional pond for villagers to bury dragon boats in riverbed silt for preservation. Digging out and cleaning the boats before the Dragon Boat Festival is an important folk ceremony.

Fig.10 Dredging and connecting wetland water systems with the traditional mud composting technique.

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Fig.11 Integrating three types of water purification technologies into the wetland water system.

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The design hypotheses for this system were to reduce wetland water system maintenance costs, improve the water quality by 1 to 2 grades, and preserve the dragon boat culture.

The monitoring and adjustment phase primarily encompasses 3 kinds of evaluation: 1) wetland maintenance costs published in the annual financial reports by the management office; 2) water quality changes monitored in collaboration with the water affairs department, to be compared with surrounding water systems; 3) documentation of annual dragon boat training, competitions, and cultural ceremonies in the wetlands.

4 Conclusions and Discussion

Haizhu Wetland Biodiversity Conservation and Restoration Project has now completed prototyping and experiment design phases. Although assessment indicators were established, the monitoring and adjustment phase has not been fully implemented, and the effectiveness of the ecological design approach remains to be further verified. However, initial monitoring data from the sites show positive trends: a significant increase in visitor number to the wetland park; an annual increase of 4 to 7 bird species observed; and the addition of 392 insect species, including 2 newly named species. The 5 designed experiments in the project have achieved various degrees of goals, with the enhanced paddy field system and bird island showing notable results, while the mound-based orchard wetland system, high-tide habitat, and low-maintenance resilient water system require further adjustments and optimization.

Specifically, in the initial stages of the bird island's development, smaller birds such as Egretta garzetta and Nycticorax nycticorax predominated, with populations reaching up to 50 individuals. A year later, larger Ardea cinerea also began nesting and breeding on the island, turning it into a rare breeding ground for Ardea cinerea in central Guangzhou. Year-round observation of waterbirds, including Egretta garzetta, Phalacrocorax carbo, Anas zonorhyncha, and Anser cygnoides on floating rafts surrounding the bird island, is possible. Shallows and wooden stakes became ideal foraging sites for waterbirds, with foraging activities primarily concentrated during low tide periods, allowing for simultaneous observation of over 30 waterbirds feeding. The enhanced paddy field system also emerged as a principal foraging site for both water and forest birds, with observed flocks of Anas zonorhyncha and Lonchura punctulata feeding in the area. Egretta garzetta, Nycticorax nycticorax, and Ardea cinerea also scattered throughout the rice fields for foraging. The fish community, including Squaliobarbus curriculus, showed sound recovery, laying a foundation for the introduction of animal observation courses in Haizhu Wetland and public ecological awareness enhancement. Shallow areas created in the high-tide habitat attracted waterbirds foraging, with single observation of over 20 individuals. But given that the water area is approximately 28,000 m², the effect was not significant, necessitating further investigation. In the low-maintenance resilient water system, invasive species such as Oreochromis mossambicus and Pomacea canaliculata continued to damage aquatic plants, limiting water purification capabilities and requiring subsequent design adjustments to consider ecological control measures against invasive species. The growth of the 54 species of newly planted fruit trees in the mound-based orchard wetland system was favorable, providing sound food source. But there was a limited observable bird population, for which continuous observation and specific enhancement strategies are needed.

These insights partially reveal how the ecological design practice, encompassing prototyping, designed experiment, and monitoring and adjustment, showcases the feasibility of integrating ecological research with practical application to steer ecological design optimization and enhance the resilience of anthropogenic ecosystems. It is essential to emphasize that this practice framework does not dismiss existing positivistic methods but frequently incorporates certain tactics. Not inherently simpler or more straightforward than the positivistic ones, the pragmatismbased methods necessitate offering a learning-by-doing and semiempirical paradigm and an effective process of learning during a purpose-driven practice, with the goal of enriching the ecological design approaches within the collective human knowledge. This approach requires landscape architects to sharpen their analytical skills regarding current ecological knowledge and prototypes, and prompts a shift in the design and engineering fields from believing that the completion of construction marks the end of their responsibilities. Thus, routines of monitoring and assessing the effectiveness of ecological design initiatives can be established. Such a paradigm necessitates the cooperative involvement of landscape architects, researchers, and management operators, granting landscape architects more freedom and opportunities to innovate in ecological configurations without strict adherence to existing morphology. Moving forward, the research team intends to further develop this collaborative framework among the realms of design, research, and management, persistently monitor the design performance, and provide quantitative proof of the efficacy of this ecological design method.

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Acknowledgements

Optimization Study on the Layout of Urban Forest Spaces in Guangzhou's Old Urban Areas, General Project of the Basic Research Program Under the Science and Technology Planning Project of Guangzhou Province (No. 2023A04J1592)

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