Introduction

Underground storage organs (USOs), such as tubers, rhizomes and bulbs are all components of a plant’s root system architecture, functionally important for storage of water reserves, as well as nutrients and carbohydrates utilisable during resprouting after fire, drought or herbivory (Freschet et al. 2021; Silveira et al. 2016). High numbers of USO plants occur in Mediterranean climate regions, which are characterised by mild, wet winters and hot, dry summers (Parsons and Hopper 2003; Procheş et al. 2006; Rundel et al. 2018). This is not surprising given USOs provide reserves for resprouting post-drought or following seasonally predictable fire events in such climatic regions (Rundel et al. 2018). They are also a common component in old, climatically buffered, infertile landscape (OCBIL) vegetation communities (Veldman et al. 2015), characterised by impoverished, low P edaphic conditions (Lambers et al. 2010; Silveira et al. 2021). Impoverished soils, combined with historic tectonic stability and minimal climatic disturbance have enabled a plethora of plant taxa with specialist survival traits, including USOs, to evolve in OCBIL regions (Lambers et al. 2010; Rundel et al. 2018; Silveira et al. 2021).

Of the five Mediterranean-type climate floristic regions – the Greater Cape (South Africa), southwestern Australia, Mediterranean Basin (southern Europe and northern Africa), California (USA) and central Chile—the former two, both OCBIL-dominated, exhibit the greatest diversity of plants with USOs (Hopper 2009; Hopper et al. 2021; Rundel et al. 2018; Silveira et al. 2021). USOs are a predictable, reliable and nutritious source of carbohydrates in First Nations’ diets (Anderson 2005; Botha et al. 2020; De Vynck et al. 2016; Gott 2005; Walsh 1990) and their high caloric dietary contribution has been suggested as an important factor in human evolution (Anderson 2016; Deacon 1993; Dominy et al. 2008; Singels et al. 2016; Yeakel et al. 2007). While the Greater Cape region is particularly USO-rich, containing an estimated 2098 geophyte species (Procheş et al. 2006), our study focused on those of southwestern Australia (Fig. 1), where at least 686 are estimated to occur (Lullfitz et al. 2021a). USO-rich families in this region comprise Orchidaceae, Asparagaceae, Haemodoraceae, Colchicaceae, Cyperaceae and Hemerocallidaceae (Brown 2022; Hickman and Hopper 2019; Parsons and Hopper 2003; Pate and Dixon 1982). Here we have examined the nature and extent of First Nations interactions with USO taxa in southwestern Australia in light of such interactions in Mediterranean-type climate regions elsewhere.

Fig. 1
figure 1

Map of southwestern Australia and Noongar Boodja (Country) showing places mentioned in text. Also included are Noongar names recorded for staple USO, Haemodorum spicatum, demonstrating differing terms for the species according to dialect. Names recorded at each place (shown as numbers on the map) are: 1) koolung (Maggie Bell & Nellie Parker in Meagher 1974); 2) bohn (Grey 1841; Moore 1884); 3) borana (Glenn Whiteman & Wayne Webb, pers. comm.); 4) miern (LK, von Brandenstein 1988); 5) kogarn (Hassell 1975); 6) quagarn (Charlie Dabb in von Brandenstein 1988)

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Scale and scope of human USO interactions in Mediterranean-type climate regions

Generally, a high concentration of USO taxa in the native flora of Mediterranean-type climate regions appears to correspond with their extensive use by First Nations people (Anderson 2005; Archer 1994; Botha et al. 2019, 2020; De Beer and Van Wyk 2011; De Vynck et al. 2016; Eoin 2016; Karous et al. 2021; Korkmaz et al. 2014; Nortje and van Wyk 2019; Singels et al. 2016; van Wyk and Gericke 2000), although this appears less so for the Mediterranean Basin than for California and the Greater Cape. In the Greater Cape, USOs are a year-round staple in the Khoe-San diet and are also valued for medicinal properties. They may be eaten raw or cooked and sometimes pounded prior to eating, taxon- and/or preference-dependent (Archer 1994; Botha et al. 2020; De Vynck et al. 2016; Eoin 2016; Singels et al. 2016; Van Wyk 2008). In California, USOs are second only to seeds in their importance as a plant food in traditional diets (Anderson 2005). In the Mediterranean Basin, USOs appear to be a lesser used plant component in comparison to leaves, fruits or seeds of wild plants (Geraci et al. 2018; González et al. 2011; Gras et al. 2020; Karous et al. 2021; Pieroni 2001), with the region of eastern Anatolia possibly a notable exception (Korkmaz et al. 2014). USO usage for food, medicine, dye and even as a pest poison is apparent across the Mediterranean Basin, but varies both at a regional and local scale (Biscotti et al. 2018; Geraci et al. 2018; Karous et al. 2021; Korkmaz et al. 2014; Tardío et al. 2006). Despite significant cultural destruction, Mapuche people in Chile and Argentine Patagonia (León-Lobos et al. 2022; Ochoa and Ladio 2015) still use a small selection of USOs for food.

Patterns of USO harvest

While a large number of USO taxa are utilised by First Nations peoples of Mediterranean-type climate regions, it would appear that certain taxa are favoured, and could be considered staples. In the Greater Cape, such taxa would include members of the Dioscoraceae and Iridaceae (Archer 1994; van Wyk and Gericke 2000), in California the Liliaceae and Asparagaceae (Anderson 2005), while Tardío et al. (2006) report that Glycyrhiza glabra (Fabaceae) is frequently targeted in the Mediterranean Basin. Species of Oxalidaceae, Santalaceae and Apiaceae are important in Patagonia (Ochoa and Ladio 2015), while in Chile, Alstroemeriaceae, Apiaceae, Asteraceae, and Dioscoreaceae are key taxa (León-Lobos et al. 2022).

In the Greater Cape, specific high-yielding ‘geophyte hotspots’ appear to have been targeted by First Nations Khoe-San people (Archer 1994; Botha et al. 2020; Singels et al. 2016). For example, Botha et al. (2020) found that the relatively fertile vegetation communities, riverine riparian woodland, sand fynbos and coastal dune-fynbos thickets produced highest USO harvest returns for contemporary Khoe-San descendents, suggesting that such areas may have been targeted by their ancestors. The authors found coastal dune-fynbos thickets especially productive post-fire, supporting a hypothesis that they were periodically burned by Khoe-San to increase productivity. Similarly, Anderson (2005) refers to regularly dug resource rich patches in grasslands, damp meadows, woodlands and forest, and describes both digging and burning as means of increasing resources at such patches. Long-standing use of dense patches of blue dicks (Dipterostemon/Dichelostemma) and Mariposa lilies (Calochortus) on California’s Channel Islands is evident (Gill 2016; Gill et al. 2021). These findings suggest that across Mediterranean-type climate regions, First Nations people have targeted and promoted some particularly productive taxa and have also favoured fertile soils rather than those growing on less fertile soils. In particular, landscape and vegetation descriptions provided by Botha et al. (2020) and Anderson (2005) respectively suggest that such targeted locations constitute young, often disturbed, fertile landscapes (YODFELs) (Hopper 2009; Hopper et al. 2021).

Skills, knowledge, roles, technology

In the Greater Cape region, USOs, in the Dioscoreaceae and Iridaceae for example, would be dug primarily with a sharpened, and often highly-prized digging stick by Khoe-San women, who would carry a small bag to collect and transport them (Archer 1994; Eoin 2016; van Wyk and Gericke 2000). Some digging sticks may be weighted with a bored stone (Eoin 2016). In California, fire-hardened digging sticks were used by women as the primary means of traditional harvest of the many USO resources accessed by Indigenous peoples (Anderson 2005; Anderson and Lake 2016). Gill (2016) illustrates use of a digging stick in a photo and also a digging stick weight or doughnut stone used by Chumash people, described as “one of the most prevalent artifacts found on [California’s] Channel Islands, and have been identified in dateable contexts to at least the last 7,500 years”. These bored stones are identical to those used in South Africa.

We found no reference in the literature to harvest digging implements or gender roles for the Mediterranean Basin, aside from an equal gender labour distribution in Tunisia (Karous et al. 2021). While Botha et al. (2020) report that a high level of skill is not required to dig for USOs among Khoe-San, they observed that those with more experience can yield higher returns. To maximise returns through targeting of known hotspots in appropriate seasons and post-fire periods and also to understand potential toxicity and uses requires Khoe-San to hold considerable specialist plant knowledge (Archer 1994; Botha et al. 2020; De Vynck et al. 2016; Nortje and van Wyk 2019; Singels et al. 2016). Additionally, Botha et al. (2019) found a high level of geographical specificity in plant knowledge among contemporary Khoe-San of the Greater Cape, which corresponds with a high spatial turnover of plant diversity. Conversely, although some narrow range endemic USOs are harvested in the Mediterranean Basin (Tardío et al. 2006), most harvested USO taxa are widely distributed albeit with localised usage and a requirement of specialist knowledge for safe, non-toxic consumption (Biscotti et al. 2018; Geraci et al. 2018; Karous et al. 2021; Korkmaz et al. 2014; Tardío et al. 2006). In this region, plant knowledge is often closely linked with use of local dialects (Biscotti et al. 2018), and it is primarily plant knowledge-holding Elders who harvest and consume USOs (Anderson 2005; Biscotti et al. 2018; Geraci et al. 2018; González et al. 2011; Karous et al. 2021; Tardío et al. 2006). Across all Mediterranean climate regions, authors raised concerns about loss of traditional plant knowledge (Biscotti et al. 2018; Botha et al. 2020; De Vynck et al. 2016; González et al. 2011; Ochoa and Ladio 2015; Tardío et al. 2006). In particular, González et al. (2011) and Ochoa and Ladio (2015) highlight potential means of revitalising intergenerational transmission to mitigate plant knowledge loss on the Iberian Peninsula and in Patagonia respectively.

It is evident that across all Mediterranean-type climate regions, First Nations peoples have utilised specific tools and knowledge to control and sustain USO procurement. Further, given extensive First Nations use of USOs across Mediterranean climate-type regions, pre- and early-colonial ecological disturbance associated with their harvest is likely to have been significant, particularly in the Greater Cape and California, in particular comprising digging of soil and use of fire to promote USO production.

Value for conservation of geophyte flora and cultural connection with traditional Country

In California, Anderson (2005) highlights specific techniques such as burning and deliberate replanting utilised by Indigenous peoples to promote USO resources, with such techniques sometimes taught through traditional story. The author also points to declines in once plentiful traditional geophyte resource patches that have resulted from colonial introduction of farming practices, as well as land clearing for urban development, fire suppression and commercial overharvesting. Tardío et al. (2006) also mention the latter as a possible threat to wild USO resources in the Mediterranean Basin. Anderson (2005) further points to colonial-induced cessation of traditional digging practice as a cause for decline of some taxa in, for example, the Liliaceae and Alliaceae, arguing that traditional harvest has a renewing effect on USO production, a suggestion made by others (Denham 2008; Gott 2005; Pascoe 2014). Anderson (2005) also describes traditional targeted patch burning techniques in California to promote USO growth, minimising shade from taller shrubs and releasing soil nutrients, and suggests a renewal of traditional human tending as an appropriate conservation strategy for some monocot geophytes, an overrepresented group in the Californian flora listed as threatened (Wilken 2006).

In a comparison of archaeological records and contemporary knowledge of Khoe-San plant usage, Botha et al. (2019) found evidence that contemporary plant usage reflects that of humans in the Greater Cape region up to 80,000 years BP, suggesting that the ecological processes associated with USO harvest have been present throughout this time. While anatomically modern human history of California and the Mediterranean Basin is shorter than the Greater Cape, Anderson (2005) suggests for California that humans may have continued such ecological processes that were previously carried out by now extinct megafauna such as ground sloths and the peccary, a scenario also plausible in the Mediterranean Basin. Moreover, other hominid species such as Neanderthals used digging sticks hardened with fire more than 170,000 y.o. in Tuscany, Italy (Revedin et al. 2020) (see Fig. 2).

Fig. 2
figure 2

First Nations use of digging sticks across three USO-rich Mediterranean climate regions, including a) Miernanger Elder, LK instructs AL on digging Platysace deflexa tubers with a wanna, Jerdacuttup, southwestern Australia (photo: SDH); b) exerpt of plate by Major Richard Shepherd from an 1846 painting by Deputy Assistant Commissary-General Neill in Brough Smyth 1878 p221 vol II, depicting Menang group, with women each holding wanna, Albany, southwestern Australia; c) 1884 photo of Khoe-San woman,|xaken-an (Mikki Streep) with her digging stick, Salt River, Greater Cape (from Skotnes 2007); d) 170,000 y.o. digging stick of Buxus sempervirens, constructed by Neanderthals in Tuscany, Italy (from Revedin et al. 2020)

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As for all traditional First Nations resource use and sustenance, USO usage is an intrinsic component of Indigenous culture and cultural identity (Janke 2021), with relevant knowledge embedded in stories, songlines and artworks (Anderson 2005; Neale 2017) linked strongly with specific family and cultural groups and to which sharing protocols pertain (Janke 2021). While the effects of colonisation and modern-living continue to threaten intergenerational knowledge transfer of USOs (e.g. Anderson 2005; Biscotti et al. 2018; De Vynck et al. 2016), exploitation and disconnection of cultural knowledge more broadly from its rightful custodians remains a major source of harm to First Nations peoples (Janke 2021; Zurba et al. 2019).

Noongar USO interactions in the SWAFR

Previously we have conservatively estimated that at least 90 taxa are utilised by Noongar First Nations people (Lullfitz et al. 2021a). In this review, we have more comprehensively examined historic and contemporary literature as well as orally transmitted knowledge of Noongar co-authors (in particular, LK) and other Noongar colleagues, to more accurately record traditional Noongar interactions with southwest Australian USOs. The object of this task was to determine the significance of such interactions for both biodiversity conservation and for contemporary Noongar people. In particular, which taxa and locations were most heavily targeted pre-colonially, and can we use this knowledge to identify areas of intensive Noongar cultural use and ecological disturbance?

To this end, and based on First Nations USO usage in other Mediterranean-type climate regions, we have gathered and examined Noongar USO usage information to test the following hypotheses:

  1. 1.

    That Noongar First Nations USO usage was a significant ecological disturbance in the pre-colonial SWAFR;

  2. 2.

    That some taxa and specific, productive resource patches, usually on fertile soils, are more heavily targeted for harvest and promoted than those growing on less fertile soils;

  3. 3.

    That knowledge in relation to taxonomy, toxicity, productivity (e.g. in relation to water, nutrient availability) and phenology, technology and specific roles and lores have been applied by Noongar to control and sustain procurement of USOs; and

  4. 4.

    That reinvigoration of traditional USO knowledge and application can be beneficial for both conservation of SWAFR biological resources and for Noongar knowledge and identity.

Methods

An extensive systematic review of peer-reviewed literature of First Nations USO usage in USO-rich Mediterranean-type climate regions outside of southwestern Australia was undertaken (Anderson 2005; Archer 1994; Biscotti et al. 2018; Botha et al. 2019, 2020; De Beer and Van Wyk 2011; De Vynck et al. 2016; Eoin 2016; Geraci et al. 2018; Karous et al. 2021; Korkmaz et al. 2014; Nortje and van Wyk 2019; Ochoa and Ladio 2015; Singels 2020; Singels et al. 2016; Tardío et al. 2006; van Wyk and Gericke 2000). For each of the Mediterranean-type climate regions, Google Scholar searches were conducted using the terms “Indigenous”, “First Nations”, “ethnobotany”, “cultural plant”, “USO”, “bulb”, “rhizome”, “root” and “tuber”. In some instances, review of a document resulted in sourcing of further relevant literature, akin to snowballing methodology. Through this review we were able to determine the scale of First Nations USO usage and application of First Nations knowledge, technology and custom across Mediterranean-type climate regions. We were also able to detect some patterns in relationship to landscape and observations of others in relation to USO conservation practice.

Contemporary and historic literature from Noongar Boodja (Country) of southwestern Australia, as well as knowledge shared orally by contemporary Noongar Elders was reviewed to compare Noongar USO usage with First Nations USO usage in other Mediterranean-type climate regions. A wide range of contemporary accounts were consulted, including peer reviewed literature, published books on Noongar plant use (e.g. Hansen and Horsfall 2019), consultants’ reports (e.g. Goode 2010) and localised studies of cultural plants (e.g. Wheatbelt NRM 2015). This search was carried out using both systematic and snowballing methods, including searches on both Google and Google Scholar, and literature already known to the authors. Search terms included “Noongar”, “Nyungar”, “Nyoongar”, “ethnobotany”, “cultural plant”, “root”, “USO”, “bulb”, “rhizome” and “tuber”. Historic sources examined included the Exploration Diaries from 1827 to 1857 held by the Western Australian Government Department of Lands and Survey and State Library of Western Australia, as well as other early colonial accounts of Noongar custom (e.g. Hassell 1975). Documents were searched using the terms “dig”, “stick”, “yam”, “bulb” and “root”, as well as USO taxa names. Personal oral recollections of Noongar Elder author (LK) and other contemporary Noongar Elders and knowledge-holders with whom we have collaborated and that were recorded in interview transcripts and/or authors’ field notes have also been included. This has been carried out in accordance with UWA Human Research Ethics Approval (reference number RA/4/20/6165). With the exception of LK, the amount of shared discussion time between authors and contributing Elders on Boodja ranged from one to six days. Noongar USO usage was discussed among other elements of Noongar TEK. The authors, including LK, have spent in excess of 100 days on Boodja together with other coauthors herein, during which USO usage has been recorded among other traditional knowledge held by LK and belonging to the Knapp family.

Records of traditional Noongar interactions with USO taxa identified through this process, as well as activities associated with acquiring USO resources are recorded in Tables 1 and 2 respectively, and Fig. 3). A table of records where taxa names could not be resolved are included as supplementary material. Where 10 or more records of a taxon were found it was determined a possible staple. For each record, where applicable, we have indicated its relevance to each of our hypotheses. Place names mentioned herein are mapped in Fig. 1. Where locations, landforms or vegetation communities of Noongar USO acquisition have been recorded in sufficient detail, they have been categorised as either OCBIL, YODFEL or indeterminate (Fig. 4). This was based on the authors’ intimate knowledge of both southwest Australian landforms and vegetation communities, as well as understanding of OCBIL theory (Hopper et al. 2021).

Table 1 Noongar Underground Storage Organ (USO) taxa recorded in historic and contemporary literature and oral history, arranged in alphabetical order of plant family. Authors’ comments included in square brackets. Superscripts 1–4 refer to the four hypotheses detailed in the Introduction. *Where Noongar knowledge/name was shared orally with authors, only names of source individuals are shown, all except Lynette Knapp (LK), a co-author, are given in full
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Table 2 References to Noongar use of Underground Storage Organs in historic and contemporary literature that do not refer to specific plant taxa. Authors’ comments included in square brackets. Superscripts 1–4 refer to the four hypotheses detailed in the Introduction
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Fig. 3
figure 3

Number of mentions in literature or contemporary oral record of southwest Australian USO taxa utilised by Noongar people. Specific families, genus and species shown as a, b and c respectively. Also shown for each taxon are the quantity for which the original Noongar knowledge holder can or can not be identified

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Fig. 4
figure 4

Number of mentions of Noongar utilised USO taxa where description of landform or vegetation community enabled categorisation of habitat to OCBIL, YODFEL or indeterminate. Recorded descriptions categorised as YODFEL habitat included ‘river’, ‘coastal’, ‘Eucalypt woodland’, ‘fertile’, ‘wetland’, ‘moist/damp soil’ and ‘alluvial’ while OCBIL habitat included ‘sand/gravel’, ‘moist among rocks’ and ‘hills’ and ‘forest’, and ‘sandplain’, ‘sandy country’ and ‘sand among rocks’ were deemed indeterminate

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Results

We located 671 records of USO usage by Noongar people in southwestern Australia. Of these records, 20 related to use as medicine, three to use as dye, and the remainder to food. Included were specific references to 25 plant families, 52 genera, and 79 species (Table 1, Fig. 3), of which there were three introduced taxa. One entire genus (Drosera) and one species (Platysace effusa) we considered to be doubtful records (see authors’ notes throughout Table 1). In addition, there were 45 mentions of Noongar USO usage for which the taxon name remains unresolved (see supplementary material). Taking into account records indicating Noongar usage of an entire genus (e.g. Thelymitra (Hansen and Horsfall 2019)), we estimate that at least 418 USO-bearing taxa have been utilised by Noongar people in southwestern Australia. Some taxa were specifically mentioned by contemporary knowledge holders or in the literature more frequently than others (Figs. 3 and 5). Table 2 details references in the literature to Noongar USO usage that are not plant taxon-specific.

Fig. 5
figure 5

USO taxa identified as Noongar staples, including a) tuber of Platysace cirrosa; b) P. cirrosa growing in typical Eucalyptus wandoo woodland habitat, Mawson; c) Platysace maxwellii growing in dune at salt lake edge, Hyden; d) Platysace deflexa growing on fringe of granite outcrop with gnamma (water hole), Jerdacuttup; e) tubers of P. deflexa; f) Typha sp. in wetland, Woogenellup; g) Typha domingensis rhizomes (photo: Barbara Dodson); h) Clematis pubescens (photo: Knapp et al. 2021b); i) Pterostylis recurva in flower, West River; j) tuber of P. recurva held by Wadandi Elder, Wayne Webb, Boranup; k) Thelymitra crinita in flower, Boxwood Hill; l) tuber of Thelymitra sp.; m) Pyrorchis nigricans in flower, Belinup; n) flower of Thysanotus patersonii; o) twining vine of T. patersonii, ready to harvest; p) tubers of T. patersonii (photo: Kingsley Dixon); q) Noongar built rock garden of Dioscorea hastifolia, Serpentine; r) tubers of D. hastifolia; s) tuber of Geranium solanderi held by Noongar Elder, Averil Dean, Boxwood Hill; t) Lepidosperma gladiatum on coastal dunes near Yanchep; u) leaf base of L. gladiatum; v) Wudjari Elder, Gail Yorkshire holding Haemodorum spicatum, Esperance; w) Mierningar Elder, LK holding Haemodorum discolor, SC looking on, Boxwood Hill; x) H. spicatum in typical sandy soil habitat, Perth. (All photos by SDH or AL, unless otherwise indicated)

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Our review revealed that there were 127 records that provide insight into the scale and scope of Noongar USO interactions (Hypothesis 1) (Tables 1, 2, and supplementary materials). Such references provide insight to a large scale, abundance and breadth of acquisition of some taxa (e.g. Orchidaceae family, Haemodorum and Platysace genus) and in the case of Geranium solanderi, that this taxon is used sparingly, and therefore its likely small scale acquisition. Numerous descriptions of disturbed ground due to Noongar USO acquisition, and also of digging implements and techniques indicate soil disturbance at scale. Ninety two records refer to landscape patterns of USO harvest and interaction (Hypothesis 2). Such records relate to targeting of fertile soil or moist locations (e.g. Platysace cirrosa, Dioscorea hastifolia), promotion of productive populations through replanting (e.g. Dioscorea hastifolia) or firing (e.g. Orchidaceae), particularly at moist, fertile locations, occurrence of USO resource patches near campsites and travel routes. In addition, where locations, landforms or vegetation communities of Noongar USO acquisition have been described, we estimate that 70% are YODFELs and 30% are either OCBILs or indeterminable (Fig. 4). We found 1034 references to specific skills, knowledge, roles or technology relating to acquisition of USO resources in the literature and oral record, with some references imparting more than one piece of knowledge (eg a taxon’s name and use) (Hypothesis 3). Such records relate to knowledge of a taxon’s name, its use, and specifics relating to phenology, season of use, toxicity and specific methods for acquisition or promotion. There were also numerous records of this nature that were not taxon-specific. Of the 1034 references, there were only 213 where we could confidently identify the Noongar person who was the source of information provided (see Fig. 3 for those relating to specific taxa). Finally, we found twenty records that relate specifically to conservation of USO taxa (Hypothesis 4), including deliberate protection or replenishment of populations (e.g. Dioscorea hastifolia) and renewing effects of harvest (e.g. Platysace deflexa).

Based on frequency of mentions, we have identified 15 species, as well as the Orchidaceae family and Haemodorum (Haemodoraceae) genus as possible staples (Figs. 3 and 5). Dioscorea hastifolia, Thysanotus patersonii, Platysace deflexa, Haemodorum discolor, H. spicatum and Typha domingensis were particularly heavily mentioned. Of specific landscapes targeted for Noongar USO harvest, most frequently mentioned were alluvial soils, wetlands and riparian areas in relation to Dioscorea hastifolia, Typha domingensis, Lepidosperma gladiatum and Thysanotus patersonii. Fertile woodlands (especially of Eucalyptus wandoo) were mentioned in relation to Platysace cirrosa, Dichopogon fimbriatus and Orchidaceae. Coastal sand was cited in relation to Haemodorum spicatum, while gravelly sand was mentioned in relation to H. discolor and P. deflexa (Fig. 4). Some commonly used species had multiple Noongar names across their distribution, varying with dialects (e.g. Haemodorum spicatum, Fig. 1).

While use of the roots of Nuytsia floribunda as well as various Eucalyptus (Myrtaceae) taxa are well known by Noongar Elders and recorded in the historic and contemporary literature, as they do not include a USO as such, we have not included these in detail in our analysis. Roots of some Eucalypt species can provide access to water, and also have edible bark (Bindon 1996, Maggie Bell & Nellie Parker in Meagher 1974, von Brandenstein 1988), while the haustoria of N. floribunda may be eaten as a sweet treat (Coppin 2008; Daw et al. 2020; Hassell 1975; Knapp et al. 2021f; Meagher 1974, Wheatbelt NRM 2009). Noongar Elder, Noel Nannup (in Hansen and Horsfall 2019) also commented that only women are allowed to dig the roots of N. floribunda.

Discussion

In this review, we have gathered Noongar knowledge of USOs in the SWAFR to ascertain the ecological role of Noongar-USO relationships. Based on a review of First Nations relationships with USOs in other Mediterranean-type climate regions, we proposed four hypotheses, comprising 1) that Noongar First Nations USO usage was a significant ecological disturbance in the pre-colonial SWAFR; 2) that some taxa and specific, productive resource patches, usually on fertile soils, are more heavily targeted for harvest and promoted than those growing on less fertile soils; 3) that knowledge in relation to taxonomy, toxicity, productivity (eg in relation to water, nutrient availability) and phenology, technology and specific roles and lores have been applied by Noongar to control and sustain procurement of USOs; and 4) that reinvigoration of traditional USO knowledge and application can be beneficial for both conservation of SWAFR biological resources and for Noongar knowledge and identity. We found support for all of these hypotheses, particularly identifying that traditional Noongar access to USOs is taxonomically and geographically extensive (Hypothesis 1), employing specific knowledge and technology (Hypothesis 3) to target and maintain resource rich locations (Hypotheis 2). Further we suggest that reinvigoration and employment of such knowledge is likely to have both conservation and social benefits (Hypothesis 4).

Scale

Our review has revealed evidence of extensive traditional Noongar USO use across a wide array of taxa (418 in 25 families), and the full geographic breadth of Noongar Boodja, which strongly supports our first hypothesis (Tables 1, 2 and supplementary material; Figs. 1, 3 and 5). Numerous accounts of extensive digging, sometimes at depths of more than a metre (e.g. for Dioscorea hastifolia), carrying of USOs when travelling, and robust, specifically-crafted wanna (digging sticks) all suggest that such interactions were substantial in scale and a significant ecological disturbance in pre-colonial southwestern Australia. That USO resources, while seasonally variable, are often available year-round suggests their value as fallback resources during scarcity of seeds, fruit or meat, which also supports this. Similar to the Greater Cape Region, this likely reflects the high diversity and prevalence of USO-bearing taxa within the SWAFR. In addition, we suggest that the finding of Botha et al. (2019) that contemporary Khoe-San plant use is representative of continual human use of up to 160,000 years in the Greater Cape is likely also in southwestern Australia for the length of Noongar occupation (i.e. more than 50,000 years (Tobler et al. 2017)), which Hallam (1989) also suggested based on archaeological evidence from the Swan Coastal Plain. Archaeological studies focused on detection of plant residues on Noongar grinding implements may help to shed further light on temporal scale.

Resource hotspots

In support of our second hypothesis, very frequent mentions in the literature of some Noongar-utilised USO taxa of southwestern Australia (eg Dioscorea hastifolia; Orchidaceae family; Figs. 3 and 5) indicate that some taxa are, or were in the past, more heavily targeted than others by Noongar, and that particular methods such as replanting and burning have been utilised to promote their growth (Daw et al. 2020; Hallam 1989, 1991, 2014) also providing support for Hypothesis 3. Noongar Elders of today still know soil, plant community and landscape conditions that will yield best USO crops (e.g. Knapp & Yorkshire in Knapp et al. 2021c), and mentions in the literature suggest that most targeted locations are YODFELs rather than OCBILs (Hopper 2009) (Fig. 4). In the Greater Cape Region, Khoe-San specifically target several staple taxa and also ‘resource hotspots’ to maximize USO returns for effort (Archer 1994; Botha et al. 2020; De Vynck et al. 2016; Singels et al. 2016). Descriptions of such locations, including coastal dunes and riparian woodlands are suggestive of YODFELs (Hopper 2009). Botha et al. (2020) also found that highly productive geophyte patches occur in recently burned sand and limestone fynbos vegetation. Anderson (2005) reports maintenance of USO resource patches through burning and replanting in First Nations California, again in landforms suggestive of YODFELs.

Knowledge, skills, technology

Detailed Noongar knowledge, skills, technology and custom are revealed in the literature and held by contemporary Elders in relation to sustained, safe and efficient acquisition of USO resources providing strong support for our Hypothesis 3. As in California and the Greater Cape, the primary responsibility for USO harvest and resource patch maintenance lies with women (Anderson 2005) and is linked closely with settlement patterns (Hallam 1989) and family travel routes (LK). Hallam (1989, 1991) suggested that this likely equates to proprietal rights to such patches being inherited through the female line, with which author, LK agrees, as women usually controlled access to resource patches. Also like Californian First Nations and Khoe-San women, a wanna for digging USOs and a cote (bag) for carrying them were both essential possessions of pre-colonial Noongar women.

Specific knowledge and skills relating to harvest techniques, taxonomy, productive habitat and phenology are evident. That Grey (1840) recorded a specific Noongar word, Nan-ga, to describe the sand-binding roots of the Haemodorum genus (Smith et al. 2011), which translates to ‘beard of the mearn’ (von Brandenstein 1988 gives ngarnak = beard, hanglet) is an illustration of the detailed science contained in Noongar traditional knowledge, which also clearly articulated the sandy soils preferred by this genus, still well-understood by Elders today, who also note its co-occurrence with other kwongkan (sandplain) taxa, such as prostrate Banksia (Proteaceae) (LK). Detailed accounts of mixing the bulbs with termite earth to increase palatability are analogous with the specific skills for efficient and safe consumption of USO taxa among Khoe San (Botha et al. 2020). As evident in other USO-rich regions (e.g.Biscotti et al. 2018; Botha et al. 2019) we also note a high degree of geographic specificity of Noongar USO knowledge, illustrated by at least six geographically specific names for Haemodorum spicatum (see Fig. 1). In biodiversity conservation practice, this highlights the importance of including people and knowledge local to the relevant dialect group on whose traditional land a project is focused. Another novel parallel with Khoe San, are Noongar Elders’ accounts of introduced weed USO taxa (e.g. LK’s consumption of Moraea setifolia) demonstrating adaptability to new conditions resulting from colonization (Nortje and van Wyk 2019).

A concerning finding of this review was that for only 20% of the Noongar knowledge relating to USOs in the literature could we identify the Noongar person from whom the information was originally sourced. This was not confined to historical accounts, but was also the case for a substantial component of the contemporary literature. This separation of USO knowledge from its custodians has potential to perpetuate the disempowerment effects of colonisation already experienced by Noongar people and families, through removal of agency and confusion of identity that otherwise would have come from intergenerational knowledge transfer and connections to specific places and plant species. Further, it often fails to record complex and subtle relationships between First Nations people, landscapes and plant communities or taxa, and thus largely mitigates against interpreting ecological effects of traditional management. Conversely, where Noongar collaborators have been identified in literature as genuine and equal partners, and specific plant knowledge is attributed to individuals, families who have been impacted by damaging effects of colonisation are able to identify their ancestors, empowering revival of knowledge, skills, connection, cultural identity and agency to care for traditional Country.

Conservation

Noongar custom dictates rules about resource conservation. This strongly supports our fourth hypothesis. Harvesting USOs outside of a plant’s reproductive phenological phase is well known among contemporary Elders and is still observed (e.g. LK’s observations of Dichopogon fimbriatus).This behaviour was also recorded historically by Grey (1841) in Hallam (2014). In addition, only harvesting resources when needed (e.g. LK’s comment regarding Geranium solanderi) is also closely observed.

That most places heavily targeted as USO resource hotspots are in YODFELs concurs with Lullfitz et al. (2021b), who found that among south coast Noongar, intensive day to day activities are carried out traditionally in YODFELs while access restrictions often apply to OCBILs. Given the often fragile soils and vulnerable, specialist plant taxa of OCBILs compared to YODFELs (Hopper et al. 2021, 2016), concentrating soil disturbance and digging of plants in YODFELs is a means of sustaining plant resources and ultimately, conserving biodiversity.

As Anderson (2005) recorded among First Nations in California, and has been found elsewhere in Australia (Gott 2005), Hallam (1989, 2014) highlighted a likely promoting effect on USO resource taxa populations, supported by references to specific methods for harvest (Knapp & Yorkshire in Knapp et al. 2021g, Maggie Bell & Nellie Parker in Meagher 1974) and propagule replanting (Bindon and Walley 1992). In an earlier study (Lullfitz et al. 2021a), we found that harvest of Platysace deflexa tubers promoted population renewal, which aligns with LK’s observation of its prominence in disturbed gravel pits. The many references to Noongar carrying of USOs when travelling also concurs with genetic homogeneity among P. deflexa and P. trachymenioides populations found by Lullfitz et al. (2020), and suggests that Noongar use of some USO resources may have influenced current population distributions, and even expanded their range.

We have estimated that at least 418 USO-bearing taxa may have been utilised by Noongar people in southwestern Australia. That we found 45 mentions of Noongar USO usage in the literature for taxa that could not be identified, and also through our own experience of identifying previously unrecorded taxa during Elder-botanist collaborative field visits, we suggest that this figure possibly remains a significant underestimate. As both Nortje and van Wyk (2019) identified in Namaqualand and Pate and Dixon (1982) previously in the SWAFR, a lack of adequate botanical identification in the historic literature makes it fraught with possible misidentification of cultural taxa and can perpetuate early errors, as we have seen in the literature relating to Drosera (Droseraceae) (see Table 1). Just as Meagher (1974) suggested, our experience is that substantial unrecorded plant knowledge remains among Elders of the Noongar community.

Based on our review findings, we suggest several critical elements for successful and respectful exploration of traditional plant knowledge to inform biodiversity conservation. These are (1) Elder leadership, (2) inclusion of individuals with good plant identification skills, potentially through taking vouchered herbarium specimens, and (3) consideration of traditional gender-based roles. Transmission of plant knowledge held by contemporary knowledge holders is most accurate through shared experience on Country, enabling both correct taxon identification and for traditional and scientific knowledge holders to jointly explore their collective understanding of a plant’s conservation requirements (e.g. disturbance response, phenology or population genetics relating to human use), thus maximising its value for information relating to biodiversity conservation strategy. Imperative in any documentation of this process is a clear link to individual knowledge holders and the knowledge that they share. This approach avoids separation of First Nations knowledge from First Nation families, the rightful holders of such knowledge, and, if required, encourages intergenerational ‘waking up’ of knowledge inextricably linked to cultural identity for current and future First Nations people. Given that Noongar USO harvest is primarily a female domain, appropriate gender-based protocol is also imperative to prevent cultural harm and maximise knowledge accuracy. We suggest that inclusion of each of these elements can set us on a path to more meaningful, inclusive conservation approaches into the future.