Here we report on a pilot study of the Living Root Bridges (LRBs) in the Indian State Meghalaya, which are grown with aerial roots ofFicus elastica, a facultative hemiepiphyte developing abundant aerial roots. Locals use these aerial roots to build living bridges, which strengthen themselves over time due to adaptive secondary growth and their capacity to form a mechanically stable structure via inosculations. An extensive inventory of LRBs in Meghalaya including data of location, altitude, approximate age and bridge length was performed in field studies. Root morphology was characterised by measurements of cross-sectional area and shape-related parameters and analysed in relation to the orientation of the roots. LRBs are found to occur mainly in the mountainous limestone rainforests whereF. elasticamay be native or traditionally cultivated. They cover an altitude range of 57–1211 m a.m.s.l. and display a length of 2 to 52.7 m. Some bridges are several hundreds of years old. Horizontally and vertically trained roots differ significantly in shape and cross-sectional area when approximately even-aged roots are compared. The results are discussed from an interdisciplinary perspective, considering the adaptive traits in the natural life cycle ofF. elasticaand possible applications in living architecture (Baubotanik).

Living root bridges (LRBs) are functional load-bearing structures grown from Ficus elastica by rural Khasi and Jaintia communities in Meghalaya (India). Formed without contemporary engineering design tools, they are a unique example of vernacular living architecture. The main objective of this study is to investigate to what extent LRBs can be seen as an example of regenerative design. The term "regenerative" describes processes that renew the resources necessary for their function. Whole systems thinking underpins regenerative design, in which the integration of human and non-human systems improves resilience. We adapted the living environments in natural, social, and economic systems (LENSES) framework (living environments in natural, social, and economic systems) to reflect the holistic, integrated systems present in LRBs. The regenerative / sustainable / degenerative scale provided by LENSES Rubrics is applied to 27 focal points in nine flow groups. Twenty-two of these points come from LENSES directly, while five were created by the authors, as advised by the LENSES framework. Our results show 10 focal points in which LRBs are unambiguously regenerative. One focal point is unambiguously sustainable, while 16 are ambiguous, showing regenerative, sustainable, and degenerative aspects. User perspective determines how some focal points are evaluated. The contrast between a local, indigenous perspective and a global, tourism-focused perspective is demonstrated by the results.

Living architecture, changing in structure with annual growth, requires precise, regular characterisation. However, its geometric irregularity and topological complexity make documentation using traditional methods difficult and presents challenges in creating useful models for mechanical and physiological analyses. Two kinds of living architecture are examined: historic living root bridges grown in Meghalaya, India, and contemporary ‘Baubotanik’ structures designed and grown in Germany. These structures exhibit common features, in particular network-like structures of varying complexity that result from inosculations between shoots or roots. As an answer to this modelling challenge, we present the first extensive documentation of living architecture using photogrammetry and a subsequent skeleton extraction workflow that solves two problems related to the anastomoses and varying nearby elements specific to living architecture. Photogrammetry was used as a low cost method, supplying detailed point clouds of the structures’ visible surfaces. A workflow based on voxel-thinning (using deletion templates and adjusted p-simplicity criteria) provides efficient, accurate skeletons. A volume reconstruction method is derived from the thinning process. The workflow is assessed on seven characteristics beneficial in representing living architecture in comparison with alternative skeleton extraction methods. The resulting models are ready for use in analytical tools, necessary for functional, responsible design.

Urban Microclimate Canopy is a digitally fabricated fiber glass structure supporting climbing plants in order to explore new ways of integrating vegetation in densely built urban environments. A prototype was designed and manufactured in the context of an interdisciplinary studio with master’s students following an approach of research by design. Varying the assembly of winding frames and fiber weaving syntax generates diverse geometric shape and structural performance. For two short-term exhibitions, ivy plants were temporarily installed in the structure. This first step was followed with a reflection of systematic integration of the growth processes of climbing plants and parametric design. An iterative solution is given, consisting of a feedback loop linking the design of the technical structure, the simulation of plant growth, and the simulation of the environmental effects of the hybrid structure. To achieve this a novel framework for simulating twining plant’s growth on network-like structures is presented: external stimuli define a cone-shaped circumnutation space (searching space model) which results in a climbing path (climbing steps model). The framework is constructed to integrate improved individual functions (such as stimuli of circumnutation) for better simulation results. To acquire more knowledge about interactions between the plants and the fiber structure, the prototype was installed permanently and planted with three different climbing plants, representing different climbing mechanisms.

Key message: Mechanical models of inosculations benefit from moderate geometric detail and characterisation of the structurally optimised area of interwoven tension-resistant fibres between the branches. Living architecture is formed by shaping and merging trees, often in combination with non-living technical elements. These structures often employ the mechanical and physiological adaptations of living trees to support structural loads. Designed and vernacular buildings utilise inosculations to redistribute forces, redirect growth, and provide redundancy. Mechanical models of inosculations in living architecture must be built according to the adaptations available to the tree. Here, mass allocation and fibre orientation are examined. Under typical gravity loads, a zone at the top of the inosculation is subject to tension. This is of particular interest because a trade-off in fibre orientation between mechanical and physiological optimisation is necessary. In tree forks, this results in specifically adapted interwoven fibres. In this study, Finite Element Analysis (FEA) is used to develop different mechanical models to fit bending experiments of four Salix alba inosculations, comparing the models’ accuracy in replicating rotations in the joint. Nine models were developed. Three levels of detail of mass allocation are considered for global isotropic (3 models) and orthotropic (3 models) mechanical properties as well as a model including the interwoven tension zone, a model of local branch and trunk orthotropy, and a model combining these two localised features. Results show significant accuracy gains come from moderate geometric accuracy and consideration of the tension-zone optimisation. The construction of the tension zone in FEA is simple and applicable to natural and artificially induced inosculations.

Living Root Bridges (LRBs), grown by rural Khasi and Jaintia communities in Meghalaya (India), are the best known example of functional living architecture. Over 70 bridges, as well as ladders, pathways and platforms have been grown from a single species (Ficus elastica), using a collection of construction methods in regionally specific environmental conditions. In general, living architecture exhibits geometric complexity for which documentation and representation tools are yet to be established. Photogrammetric surveys provide data-rich point clouds which could be useful for analysis and design specific to living architecture. This study provides the first photogrammetric surveys of LRBs. Useful point clouds were produced for several bridges, as well as joint details. The method is found to have a range of benefits: providing detailed views, showing environmental conditions, and allowing for time analyses. The wider application of photogrammetry to living architecture is discussed, particularly with regards to Baubotanik structures and the improved documentation and representation of LRBs as a unique architectural typology. The need for developing a tool for topological model extraction, and possible methods therein is discussed.