*7.1. Is Kalo Cultivation a Keystone Component of the Hawaiian Social-Ecological System?*

*Kalo* cultivation displayed high dominance within cropping systems, being dominant or co-dominant in all three systems identified, and within biocultural functional groups, being dominant in multiple important groups. Furthermore, *kalo* is dominant within the most important functional group—the cultivation of complex carbohydrates. But do the metrics we've identified adequately capture the importance and impacts of *kalo* within the Hawaiian social-ecological system, especially as relates to structure and function of the system as a whole? These questions are explored in a discussion below.

### *7.2. Biocultural Relationships between Kalo and Hawaiian Culture*

Through the original voyages of Polynesians to what is now known as the Hawaiian Islands a total of at least twenty-seven plant species and six animal species were established in Hawai'i [63], collectively referred to as a "portable biocultural toolkit"—a term we apply to the suite of plants and animals that cultural groups take with them in their diaspora across the globe. The taxa selected were likely chosen because they—through their pre-established links to sociocultural practices—could facilitate the perpetuation of key biocultural functional groups (e.g., eating food, drinking liquid, healing with medicine, clothing production, religious ceremony, storing food, etc.) upon arrival at a new destination. They were also the vehicles for transporting stories, which helped retain lessons about life, family, and culturally-appropriate behaviors; and, therefore, represented important teaching tools for future generations.

As the Hawaiian culture developed, *kalo* came to hold a pre-eminent role on both a practical and philosophical level. This is reflected in a high level of pre-contact diversity with approximately 400 distinct cultivars of *kalo* that the Hawaiian culture co-evolved with [18]. Not only was *kalo* the preferred staple food, but it was also considered to be the original ancestor of the Hawaiian race [54] and the ancient religious system [55,58]. Furthermore, there are many philosophical and symbolic links observed linguistically between the parts and growth form of *kalo*, and the Hawaiian family system and its structure [54].

Evidence for the central importance at which *kalo* was deeply ingrained within the identity, dietary system and religious beliefs of the Hawaiian people is seen in the ancient proverb "*Ola ke kalo, ola ke kanaka*", which roughly translates to "As long as *kalo* lives, so shall the Hawaiian race"; the converse implication is that if *kalo* were to disappear, so too would the Hawaiian race [18,64]. It is apparent that due to its central importance in the identity, diet, and religion of the ancient Hawaiian society its hypothetical disappearance would drastically alter the cultural subsystem that was built upon it—not only because of its direct importance, but also because of secondary extinctions which would occur due to the breaking of linked biocultural relationships. Thus, it certainly satisfies the Garibaldi and Turner [11] definition of *cultural* keystone *species*, at least within the context of pre-contact Hawaiian culture. One could also argue that the practices associated with *kalo* satisfy the Brosi et al. [12] definition of "*cultural* keystone *practice*" in the same pre-contact period. However, beyond establishing *kalo* as a "*cultural* keystone *species*" and the traditions associated with it as "*cultural* keystone *practices*" via an *a priori* assessment, this paper takes a quantitative approach to determining which specific biocultural relationships can be considered keystone components of the Hawaiian social-ecological system.

#### *7.3. Kalo Is a Dominant Component in Hawaiian Cropping Systems*

*Kalo* was a dominant component in all three cropping systems—rain-fed, agroforestry, and flooded-field—employed in the Hawaiian social-ecological system. '*Uala* (sweet potato) was co-dominant in rain-fed systems, which is a strong indicator of functional redundancy in that group. This means that the structure of rain-fed systems could, theoretically, still be maintained in such systems, if *kalo* was not utilized for some reason. The same could not be said for flooded-field systems; the results indicate that *kalo*'s disappearance would result in structural shifts, and potential collapse, in that cropping system. Overall, no cropping system was overbearingly dominant in Hawaiian agriculture when viewed at the scale of the archipelago. However, the spatial distribution of agricultural opportunities was not evenly distributed across the archipelago [27], and the loss of *kalo* would have had different effects based on the local reliance on different cropping systems. Particularly on the oldest island of Kaua'i, where flooded-field agriculture was highly dominant, the theoretical loss of *kalo* would likely drastically disrupt the entire society. This would not necessarily be the case in leeward Hawai'i and Maui Islands, where rain-fed agriculture dominated. It could be argued that the functional redundancy was being enacted in rain-fed systems on the younger islands of Maui and Hawai'i, where shifts in the dominant deity (from Kane to Lono) and the development ¯ of religious sects occurred in areas that, due to environmental limitations of *kalo* cultivation, were dominantly dependent on *'uala*.

#### *7.4. Kalo Is a Dominant in a Key Biocultural Functional Group*

Of all the biocultural functional groups associated with Hawaiian agriculture, the most important was "cultivating a complex carbohydrate as a food source" (Table 3). Within that biocultural functional group, *kalo* was a strong dominant with no co-dominant (Table 3). Theoretically, this means that if *kalo* was not used in agriculture systems, for whatever reason, the structure of those systems would shift into an altered state, especially in light of the unique agricultural practices associated with *kalo* cultivation as described by Handy et al. [54]. In rain-fed systems, *kalo* could theoretically be replaced by its co-dominant (*'uala*, sweet potato), but the structure of those systems would shift due to the different agricultural practices associated with the cultivation of each species. For instance, *'uala* matures more

quickly, and also has a more confined harvest and storage time, indicating that compared to *kalo*, an *'uala*-based system would require a more mobile labor force, and more consistent time in the field to manage the shorter harvest periods. More planning and balance would be needed to manage the short window of harvest for constant food supply, and the systems would likely be more vulnerable to both environmental and social perturbances such as drought or war.

In agroforestry systems, *kalo*'s dominance was due to its ability to grow in low light conditions and, more importantly, be able to store in ground for extended periods and self replicate—all traits that are condusive to its cultivation in these systems. It could be replaced by a redundant component of the sub-canopy layer in that system, but the structure of that system would also shift. In flooded-field systems, there was no redundant component in the pre-contact period that could be grown in such flooded conditions. Therefore, if *kalo* was not cultivated in that system, the lack of a functional redundant would result in an inability of that system to exist, which would result in a structural shift in cropping systems if agriculture was to continue.
