Noah Kaʻaumoana, mālama ʻāina specialist, harvesting kalo in Limahuli Garden. Photo by Joshua Diem.
By Joshua Diem, Mālama ʻĀina Tech II
Here, in Limahuli Valley, the mountains rise above the clouds, as though tethered to earth by the roots and vines of a changing landscape, their black volcanic faces gazing out across the vast Pacific. Carved from basalt, the mountains stand as ancient warriors, abstract and muscular, as if shaped by a wild, surrealistic deity. Here, the pōhaku (stones) have names, stories, and characteristics as distinct as you or I.
As if chiseled by a sculptor, fallen stones populate the valley floor to form boulder fields. Rainwater from cloud forests — the wao akua — feeds the stream below, braiding its way to the ocean, splitting the valley into east and west. To navigate the 600-acres of the Lower Limahuli Preserve, imagination is perhaps your most essential companion.
I began my work as a field technician in the preserve. Uncovering the valley’s rich history and enduring traditional practices propelled me towards my graduate studies in landscape architecture at Harvard University. What began as a series of inquisitive sketches of these ancient walls, evolved into three years of research for my design thesis. The objective was to uncover the archaeological framework of an indigenous agroecological system within Limahuli Valley, exploring how it can be revitalized and incorporated into broader restoration efforts. Doing so can exemplify a new standard of biocultural conservation. This project presents a vision for reinterpreting the valley’s legacy through its stonework.
The site of my research is the 2.8 acre ʻilipaʻa (agricultural homestead) built several centuries ago between the Limahuli Stream and the valley’s western wall. Standing below Mauna Hou and Maunapuluʻō peaks, the site includes over one hundred interconnected loʻi (flooded terraces) once used for irrigating kalo (taro).
The primary house site, positioned at the compound’s midpoint, allowed its inhabitants to oversee water management and crop rotation. Assuming wetland crop yield was comparable to today, this agricultural system may have sustained a family unit of approximately 20-50 members. We are uncertain of the identity of the ʻohana (family) who once inhabited and nurtured the site or how they or their ancestors moved the stones. Whoever fed from this place, cared for the source of its wai (fresh water).
Aerial plan view of reconstructed ʻilipaʻa (agricultural homestead) in the Lower Limahuli Preserve. The stone complex includes home sites and terraced agriculture that follows the natural contouring of the landscape and drainage basins. The plan identifies loʻi (flooded terraces) and ʻauwai (irrigation waterways) most suitable for restoration based on field observations and collected data. Rendering by Joshua Diem.
Today, overgrown neke fern swamp hides the existence of the puna wai (fresh-water spring) that continues to seep from an opening in the valley wall. Channeled into the ʻauwai puhi (main irrigation ditch), gravity directs the flow of water, initially tracing its line along the base of the pali (cliff). The ditch crosses a small aqueduct-like structure and pools in a check dam. Finally, the water is distributed into the loʻi kalo. Top of FormBottom of FormWhen this landscape was actively cultivated, it must have evoked a profound sense of rhythm and connection.
This ʻilipaʻa was likely inhabited until the mid-19th century when its abrupt abandonment may have been the result of sweeping changes in property tax laws throughout the Hawaiian Kingdom. These policies reflected the broader social, political, and economic changes in Hawai‘i during that time and left the valley without its stewards.
Tapestry of ancient landscapes
Walking into the Limahuli Preserve is like traveling through time. Step off the trail and you risk getting lost in a dense tangle of vegetation. All but hidden to the unfamiliar eye, the landscape is a dynamic expression of the interplay between people and their environment with remains of the terraces, irrigation channels, and house sites. Garden plots that once flourished now lie overgrown and hard to recognize.
To recover these ruins, the site was surveyed and validated using GPS and Lidar instrumentation. The collected data was then integrated into architectural design software to build models of the site.
The valley’s landscape is a complex tapestry of social, cultural, and ecological narratives that make up the ahupuaʻa system of resource management. This centuries-old traditional land division, often similar to the shape of a watershed, allowed Hawaiians to organize and sustain resources through planning, interconnectedness, and cultural values.
Remnant terraces covered in vegetation. Photo by Claire Ragozzino
Over time, my ability to discern the role of stone within this valley’s ahupua’a system was refined under the guidance of my mentors and colleagues, Moku Chandler and Noah Kaʻaumoana, both stewards of Limahuli Valley and masters of traditional stone craftsmanship. Through their mentorship, stone has revealed itself. Ancient architecture seemed to emerge naturally from the earth, unveiling its framework and function.
It is not merely the ruins themselves that have captivated me, but rather their spatial relationship with the land’s physical form. There exists a profound sense of alignment, where the landscape became a canvas of stone walls, patterns, and symmetries, constructing a narrative that can be read like braille.
The first Polynesians who arrived here had to adapt to a range of environments, building agricultural systems that mirrored the natural processes and features of each ecosystem. For a river valley like Limahuli, land suitable for growing kalo was typically found in alluvial flood plains adjacent to the stream. By manipulating the water flow in these plains, wetland kalo became the central crop of the early Hawaiians and a symbol of the kinship between humans and the land. The intuitive natural design of these irrigation systems was the result of generations of cumulative knowledge, tailored to the distinct characteristics of each environment and the creative choices made by the makaʻāinana (people who tended the land).
Restoration and revitalization
Today, one of the primary objectives of NTBG’s work in the Limahuli Preserve is to restore native forest. But the archaeological clues that remain in the landscape should not be overlooked. As a landscape architect, I think beyond the ecologic functionality of a place to also consider its beauty, stories, and human-introduced qualities. Working in the valley, I have filled my field notebooks with architectural illustrations, documenting my observations and understanding of how this landscape functioned in an earlier time. By retracing the genius in the placement of the stones, we can recover a framework from when this site was an integrated forest where agriculture thrived.
Left: Joshua taking notes in the Limahuli Preserve. Photo by Claire Ragozzino. Right: Remnant rock terrace. Photo by Joshua Diem.
This ʻilipaʻa site holds great promise for restoration. Much of the invasive understory that has engulfed the valley floor has yet to encroach and many of the rock walls remain intact. The source of irrigation water still flows and, importantly, the site falls within the active restoration zone of the Lower Limahuli Preserve, accessible by a short hike.
The loʻi terraces serve as the foundational architecture that informs the restoration process. Through the strategic and phased removal of invasive canopy trees and the excavation of the ‘auwai, water can flow back into the landscape. Native restoration plantings can be interwoven into the water system to create a novel space that embodies biocultural conservation.
The integration of this historical agricultural system has the potential to serve as a haven for endangered water birds, nourish restoration plantings during periods of drought, and utilize natural drainage to improve soil fertility. Furthermore, the reintroduction of traditional farming practices and passive food production is significant as an expression of the community’s most cherished values and highest aspirations.
As we strive to restore native forest, it is important that we help perpetuate the agricultural legacy surrounding us. Throughout Hawaiʻi, other sites of great cultural heritage exist on conservation lands, waiting to be rediscovered and revitalized. Limahuli Valley can serve as a model for a new integrated approach to stewarding Hawaiʻi’s future in a way that builds bridges between the humanities and science.
Find Joshua’s design thesis at: Biocultural Design Landscape Design and Masterplanning
Left: Moku Chandler, mālama ʻāina specialist, in Limahuli Garden. Photo by Erica Taniguchi. Right: Joshua in Limahuli Preserve. Photo by Jon Letman.
 Wao akua refers specifically to a high elevation sacred realm of the gods
 Colocasia esculenta
 Cyclosorus interruptus
 Light Detection and Ranging remote sensing method of measuring variable distances to the Earth