Trees to remember: culturally modified boab trees in the face of climate change

ABSTRACT

Culturally modified trees (CMTs) are a unique form of archaeology and cultural heritage. There are several factors affecting the survival of culturally modified trees in Australia, and these will all likely be exacerbated by climate change. Boab trees (Adansonia gregorii), which are endemic to northwest Australia, have been subject to modification by Indigenous people both prior to and following the settlement of the Kimberley region by European and Anglo-Australians. Many of the potential impacts of climate change on boab tree survival are yet to be determined, but a range of new threats are emerging as potential endangerment. Through the insights of Indigenous knowledge, this paper discusses one particularly significant boab tree in Nyikina Country and how its demise may be linked to erroneous human actions in the recent past. This provides a unique perspective on how the complexities of climate change may be conceptualised through living knowledge and experience.

KEYWORDS:

• Culturally modified tree
• Australia
• Indigenous knowledge
• boab
• Kimberley
• photogrammetry

Introduction

Culturally modified trees (CMTs) are a unique form of organic archaeology and cultural heritage. CMTs are found throughout the world and reflect a diversity of cultural values and uses. In addition to utilitarian and symbolic functions, modified trees may carry spiritual significance or hold deep cultural attachment for Indigenous peoples. In many cultures, as Turner et al. (2009, 260) succinctly frame it ‘functional and spiritual aspects of CMT use are intertwined’. In some Indigenous communities, specific living trees are regarded as central to the ancestral fabric of the landscape and interacting with them in the present is a way of connecting with the past, place, and traditions that knit them together with living beings. Thus, tree modification practices can reflect longstanding customs and unique Indigenous knowledge shared over generations, which in turn can lead to an understanding of specific tree species and how to manage their preservation. There are historical and contemporary examples of trees that have been culturally modified in a manner that enables resource use while also ensuring sustainability (Turner et al. 2009). Nevertheless, culturally modified trees, particularly those that are living, are a finite resource susceptible to a range of threats, many of which are amplified by current and future conditions of climate change.

In this paper, we discuss CMTs within Australia, specifically the boab tree (Adansonia gregorii), a species of tree endemic to northwest Australia, which was subject to modification by Indigenous people both prior to and following settlement of the Kimberley region by European and Anglo-Australians (Figure 1). Although the practice of culturally modifying trees was widespread throughout Australia, the archaeological literature is relatively sparse and heavily reliant on historical documentation, dead CMTs and their fragments preserved in museums.

Figure 1. Map of the Kimberley region, Western Australia with locations mentioned in the text. Source: ANU Cartography.

In the Kimberley, trees were used for food and other resource extraction as well as in the practice of ceremony, and for burial practices (Love [1936] 2009). The boab tree was culturally modified in a number of ways by Indigenous people, and later by non-Indigenous settlers and visitors (Kenneally 2012; Lowe 2019). The softness of the boab tree’s bark and the expansive surface area of its often multi-stemmed trunks and large limbs allows for the carving and painting of designs (Blundell and Woolagoodja 2005, 146; Crawford 1968; O’Connor et al. 2022) as well as names and textual inscriptions that relate to the region’s more recent cross-cultural history (Frederick, Balme, et al. 2022; Lewis 1993). While there are no published studies of the antiquity of Australian boabs, AMS dates of the closely related African baobab species (A. digitata) have shown that they can live to over 2000 years (Patrut et al. 2018). As Australian boab trees are also probably exceptionally long lived, it is highly likely that trees with carvings made prior to European colonisation survive to this day. Carvings on boab trees recorded to date include naturalistic renderings of animal tracks, snakes, crocodiles, names and initials, as well as ancestral beings such as Wanjina (Crawford 1968; Frederick, Balme, et al. 2022; O’Connor et al. 2022). The significant size and unique physical form of old boab trees make them distinctive landscape features and many individual trees have taken on a landmark quality. Hence, boab trees are also a focus of signposting, messaging and camping for non-Indigenous people travelling through the Kimberley in association with exploration, pastoral and tourism activities.

For the Indigenous peoples of the Kimberley, the boab tree is both an everyday and vitally important part of the cultural landscape. The boab has various edible and nutrient rich components and was a valuable source of water and shade during the hot and dry months of the year. Traditionally, the boab tree also provided other resources such as fibre for string, and its seeds or ‘nuts’ were used as toys and rattles to accompany singing in dance and ceremony (Akerman 1993; Balme et al. 2022). Beyond their functional resource value, boab trees are entwined in the Indigenous knowledge system of Country and the foundational world view, Law, stories, and guiding principles of Bookarrikarra (the Dreaming) for Nyikina and Mangala people of the West Kimberley.

Among other plant and animal species, the boab tree is a key part of the Kimberley environmental landscape. As such, it is integrated into traditional ecological knowledge and features in local seasonal calendars (WAC 2020). The flowering of trees, the emergence of seeds, and the loss of leaves are some of the signs that speak to changing seasons and meteorological conditions in northern Australia (Goudie 2007; Rose 2005). Variability and extremity may feature as part of a dynamic seasonal system, but through ‘observation and experience of interactive local events’ (Rose 2005, 39), people may be able to read the signs of notable weather events, such as the onset of wet season rains in a boab’s shooting leaves (Goudie 2007, 124).

In this context, it may be useful to regard modified boab trees as ‘vivifacts’, following Kawa et al. (2015), because their presence in the extant archaeological record is largely dependent on them being alive. Beyond their value as living artefacts, culturally modified boab trees are key features of the Kimberley landscape and its cultural and natural heritage. It is likely that they, like other large old trees, play a critical ecological role in their local environments (Lindenmayer and Laurence 2017). The concept of vivifact underscores the entanglement of the boab in a much larger system of ecological processes and acknowledges the network of dynamic plant-human-animal-soil-hydrology-meteorology relations that makes up a living landscape. Not all Australian CMTs may be regarded as vivifacts because they may also include dead standing trees or the wooden remains of a CMT that has been preserved. However, unlike other Australian tree species used for cultural modification activities, the boab tree quickly collapses and disintegrates following death (O’Connor et al. 2022).

Culturally modified trees in Australia – managing a finite resource

Tree modifications were traditionally made by Indigenous people using stone axes and, later, metal tools. The scars of bark removal and incision may be found on both living and dead trees of various endemic species throughout Australia. Since the colonisation of Australia, natural events and anthropogenic processes have resulted in the loss of hundreds of documented culturally modified trees.

Within Australia, research on Indigenous CMTs has generally divided trees into two categories: those that are scarred as a result of bark removal, usually for a utilitarian purpose; and those that have carvings made in the bark (dendroglyphs) as part of secular or ceremonial activities. Early recordings of dendroglyphs reveal a diversity of techniques and designs, some incised and painted (Mathews 1896), some carved into heartwood, some figurative and others geometric in form. The CMTs recorded throughout Australia reveal a diverse use of bark for the production of canoes, shields, and as material for clothing (bark blankets) and making shelters (Brayshaw 1974; Long 2005; see Donald Thomson’s photographs in; Wiseman 1996). They show the removal of heartwood for the manufacture of spear throwers (woomera), carrying vessels (coolamon) and other modifications to obtain food such as wild honey (sugarbag), possums, grubs, nuts and water (Cahir 2012; Long 2005; McGregor 2019). Modified trees which have received less attention are those that have been altered as a result of art and cultural activities – such as cutting bark for string, making dyes or tanning skins (Long 2005; McGregor 2019) – and those which have additive modifications such as nails and chains embedded in the bark (Frederick, Balme, et al. 2022).

In some cases, particular species of trees were/are favoured for particular materials and uses, such as the stringy-bark tree (Eucalyptus tetradonta) commonly used for bark paintings and structures in northern Australia, the Ironwood tree (Erythrophleum chlorostachys) for carved mortuary poles on the Tiwi Islands (Hoff 2000), Bombax ceiba and Brachychiton diversifolius for carved sculptures (Koenig, Altman, and Griffiths 2011) or the Brush Kurrajong (Commersonia fraseri) for use as fishing spears in the south of NSW (Nash 2012). Trees may be expected to survive some modification activities, but in other cases the trees may be destructively harvested and consequently leave no archaeological signature as CMTs.

As a cultural practice, the modification of trees can be an important teaching and learning occasion that can involve the transfer of skills and sharing of information between individuals as well as through the acquisition of tacit knowledge (Nash 2012).

Trees were also marked by non-Indigenous explorers and settlers for mapping purposes, to create landmarks, and as a historical record of their journeying (e.g. Govett 1830–1835). Early settlers sometimes engaged Indigenous people to cut bark for them and also adopted Indigenous techniques of bark stripping learnt through observation (Cahir 2012; Long 2005). Given the regional diversity and vast differences in species, resource extraction and tree modification across Indigenous Australian cultures, it is difficult to succinctly attribute the range of cultural activities to particular tree species. As Long (2005, 57) notes, within the state of New South Wales alone:

Common scarred tree species include river red gum (E. camaldulensis), swamp box (Tristania suaveolens), yellow box (E. melliodora), grey box (E. moluccana), white box (E. albens), white mahogany (E. acmenoides), red box (E. polyanthemos), blackbutt (E. pilularis), stringybark (E. eugenioides) and brown barrel (E. fastigata). Other species known to have been scarred for more specialised purposes in localised areas include paperbark (Melaleuca sp.), Moreton Bay Fig (Ficus macrophylla), black bean (Castanospermum australe) and ironbark (Eucalyptus sp.). Ironbarks do not appear to have been used extensively.

Some of the most distinctive CMTs within Australia are the carved trees in Gamilaroi and Wiradjuri countries of eastern Australia. Known for their complex geometric designs and ceremonial significance, these trees were the subject of attention among non-Indigenous settlers and collecting institutions in the late-nineteenth and early-twentieth centuries. As a result of this interest, many carved trees were mapped and photographed, but many were also removed, without local Indigenous community permission, and carved sections sent to state and university museums where they remain in storage. Other carved trees were destroyed by early settlers for firewood or in the course of clearing the land (Black 1941, 17). Some trees also died naturally but, because they were of a durable timber, a portion may remain standing or able to be removed and preserved (Black 1941; Etheridge Jnr 1918). In fact, CMTs continue to be documented archaeologically in different parts of Australia, with many of these remaining as standing dead trees, stumps or felled logs rather than living specimens (e.g. Spry et al. 2020; Tutchener 2018).

Concerns over the preservation of CMTs first arose among the settler Australian community in the early twentieth-century, with a number of individuals embarking on documentation programmes (Black 1941; Etheridge Jnr 1918). One consequence of this activity is that some carved trees were collected and stored in museums. At one point in time, the removal of carved trees was advocated as a preservation measure (McCarthy 1945) but as researchers came to acknowledge the deep association between a CMT and its location, emphasis was placed on maintaining CMTs in situ (Geering, Ravenscroft, and Roberts 1991).

In the state of New South Wales alone thousands of Indigenous CMTs have been recorded, however less than 100 carved trees remain in their original locations (Grimwade, Mickan, and Darroch 1995; Purcell, Briggs, and Sutherland 2011). More recently, many museums within Australia have undergone repatriation procedures, and carved trees are among the Indigenous belongings that have been returned to local communities. This has brought new meaning to some carved trees as ‘a marker of reconciliation’ (Purcell, Briggs, and Sutherland 2011, 14) and demonstrates the very real connection that CMTs forge between the past and the present.

Aside from mapping, photography and the deliberate removal of CMTs for ‘preservation’ purposes, there have also been non-destructive techniques applied in order to retain the integrity of CMTs in situ (Buhrich and Murison 2020; Grimwade, Mickan, and Darroch 1995). These strategies have involved the replication of a specific portion of the tree such as a carving or scar. Physical replication methods using latex and fibreglass moulding have been successfully applied to rainforest tree carvings in Queensland and 3D photogrammetry techniques have enabled the reproduction of tree scarring and carving in digital form (Buhrich and Murison 2020; Dardengo 2019; Frederick, Andrews, et al. 2022).

Climate change, archaeology and the Kimberley region of northern Australia

Despite a growing concern over contemporary anthropogenic climate change observed within the Australian archaeological, cultural heritage and broader communities, research in this field remains in its infancy. The vulnerability and potential resilience of cultural heritage resources and the archaeological fabric, as well as the effects on and response of Indigenous communities are, nonetheless, vital considerations for any future-oriented practice in Australian archaeology. This may include but extend beyond the physical loss of sites and artefacts of antiquity to affect the cultural and spiritual wellbeing of individuals and communities. This is all the more evident where archaeological sites constitute part of the living landscape, contemporary resource base and extant belief system or cosmology of the Dreaming.

Internationally, there is increasing awareness among archaeologists that more could be done to actively address the challenges that climate change presents for the day-to-day practice of archaeology and the implications it has for the survival and maintenance of the archaeological record/cultural heritage resource (Mitchell 2008). In Australia, recognition of this fact has increased over the last decade with interdisciplinary and community driven studies emerging (Leonard et al. 2013). This is pertinent considering Australia is the driest permanently occupied continent on Earth and the effects of climate change witnessed in recent years include an increase in the intensity and frequency of extreme weather events such as catastrophic storms, major bushfires, massive flooding and previously unrecorded weather patterns and temperatures. Modelling suggests that this trend will only intensify in coming decades (CSIRO 2015). The most recent climate change projections for northern Australia indicate that temperatures will continue to increase, with more hot days and over longer durations. Rainfall patterns will change, and extreme events are predicted to increase. Cyclones, whilst less frequent, will be more intense (www.nespclimate.com.au). Despite this, little research has been conducted on the effects of climate change on particular Australian biota, and studies that specifically address the Australian boab tree are limited (Kempe, Neinhuis, and Lautenschläger 2018).

Boab tree vulnerabilities and climate change

The Australian boab tree has thrived in the unique ecological, geological and climatic conditions of the Kimberley for millennia, with individual trees believed to be capable of living up to hundreds if not thousands of years. Because the boab tree’s lifespan is considerably longer than many other native Australian tree species, carved boab trees may be expected to have outlived other CMTs that have perished over the last two centuries. Despite their long life-span, boab trees are, nonetheless, susceptible to a wide range of impacts.

Like other trees, boabs may be destroyed by clearing, insect and termite attack, fungal infestation, lightning strike, fire and natural ageing. Many of these vulnerabilities are amplified by the effects of anthropogenic climate change. Severe storm events lead to high winds, and flooding has the potential to waterlog soils and destabilise the root system of the tree, break limbs or even blow it over. This is compounded by agricultural and pastoral activity as vegetation clearing for pasture has resulted in the ‘stranding’ of the few large old trees remaining in paddocks, making them more vulnerable in high winds. In addition, tropical storms can cause significant activity, and lightning strikes may fell a tree or lead to wildfires. Any injuries to the tree resulting from such weather events may also predispose it to disease and hasten decay.

As recent studies have indicated, it is ‘important to recognise that climate change not only exacerbates and multiplies existing vulnerabilities and threats, but also introduces new risks’ (Hollesen 2022, 1388). One obvious threat to Kimberley boab trees located in coastal tide zones is the rising sea level, causing increased salinity. There are also numerous flow-on effects arising from increased temperature and evaporation such as impacts on the groundwater levels upon which boabs rely, or the fact that cattle in search of feed, particularly during times of drought, will eat the outer bark of boab trees. Moreover, some of the key characteristics of large old boab trees can also make them more prone to dangers of climate extremes. For example, large boab trees are often sparsely distributed, their isolation, height and extensive branching making them particularly vulnerable to lightning strikes. Irrigation for agriculture, which can affect the water table, and reduce the amount of groundwater available to the root systems of trees, may be compounded by the effects of climate change.

In summary, it is still unclear how global warming and changing climate are impacting Adansonia gregorii specifically, but research on related baobab tree species from Africa may provide some insights. Modelling of suitable habitat for baobab distribution, under current conditions and future climate projections indicates a likely contraction of the geographic range for many species of Adansonia (Birhane et al. 2020; Wan et al. 2021). Findings suggest temperature is the most important factor for baobab distribution patterns, with a ‘high vulnerability of the species to extreme warming’ (Birhane et al. 2020, 10). In the last decade nine of the 13 oldest and five of the six largest trees recorded in Botswana, Mozambique, Namibia, South Africa, Zambia and Zimbabwe by Patrut and colleagues have died, and researchers have suggested that sudden tree deaths are a result of climate change (Patrut et al. 2018).

As boabs are so long-lived, it is rare for people to experience the death of a tree. Our research sought to understand what the death of the boab tree at Windankooroo meant to contemporary Nyikina people and how its death was understood by the elders through traditional Indigenous knowledge.

Windankooroo – a tree to remember

In 2021, we undertook fieldwork to locate and document carved boab trees in Nyikina and Mangala Country of the West Kimberley. We visited carved trees that were known to Traditional Owners, including one that had recently collapsed. This tree, located at Windankooroo on Liveringa Station (Figure 1), marked an important Bookarrikarra place for Nyikina and Mangala people who often used this as a resting and watering place, or picnic spot during travels through Country. At the time of our initial visit, the boab tree had only recently died, and its limbs and branches had begun to deteriorate and rot (Figure 2). As boabs are so long lived, it is rare for people to have experienced the death of a significant tree. Many of us (UF, SO’C, WA, JB) had never seen the Windankooroo tree before. We were unable to compare the collapsed tree in front of us with the vivid memories and stories that others (AG, HG, MM) were able to share. Visibly concerned by its loss as they walked around the collapsed structure of trunk and branches, traditional owners Annie and Hilda recalled how Nyikina and Mangala people would wait or meet up at the tree and that you could scoop water from the tree for drinking. Now we could only make out a few carved initials in the degrading bark, but we could still see where freshwater pooled at its centre.

Figure 2. Visiting Windankooroo in 2021. Photograph: UK Frederick.

Due to its significance to the community, we recorded the tree using a DSLR camera and 3D photogrammetry methodology. A photogrammetric model of the tree was subsequently generated using RealityCapture software and renders made using Blender, which is capable of generating much higher quality renders with realistic lighting conditions (Figure 3). In June 2023, we revisited the site of Windankooroo to record the Nyikina story associated with the tree (Figure 4). However, within the two-year period between our two visits, the tree had disintegrated so extensively that it was visible only as a depression where its massive trunk had once entered the ground (Figure 5). Across the surface was a scatter of small wood fragments and a single reasonably sized piece of remnant tree. It was therefore important to understand what the death of the boab tree meant to contemporary Nyikina people and how it was interpreted or understood through traditional Indigenous knowledge. The story and memory of the tree was shared on site by Nyikina elder and co-author Annie Milgan. As is often the case in Indigenous ontologies, the death of the boab tree was not seen as having a monocausal explanation but rather was connected to a web of issues involving climate change among other factors of ecological disruption wrought by post-colonial impacts on the land.

Figure 3. Views of the 3D rendered model of the Windankooroo larrkarrdiy. Source: W.R. Andrews.

Figure 4. Visiting the place of Windankooroo in 2023. Photograph: WR Andrews.

Figure 5. Very little of the Windankooroo larrkarrdiy remains in 2023. Photographs: WR Andrews.

In telling the story of the boab tree, its history and meaning, Annie’s narrative moves through what seem to be different temporal settings but which resonate through the past and present. Thus, at times, the tree is spoken of as if it were still living.

As Annie recounts, the larrkarrdiy (boab tree) at Windankooroo was a significant tree. It is associated with a Bookarrikarra (Dreaming) story involving an important figure called Woonyoomboo who was responsible for naming the country as he was journeying [Annie explains ‘he was a mapping man and a scientist’]. The larrkarrdiy at Windankooroo was very special and had an important association with ceremony. When they had ceremony called Kamba (named for the freshwater crab) at Libirrirrbirrin (the billabong on Liveringa Station)‘ Woonyoombo brought the young men over to Windankooroo after the initiation as he knew there would be water in this larrkarrdiy. He put them close to the water and left them there for several weeks until they were smoked and could leave free. He left the young initiates at this tree because he knew that there would be water.

People would use this tree and water if they were fishing here. People would come here to get water from this tree which collected in a hollow. They would use the empty seed pod of the larrkarrdiy and coolaman or more recently the billycan to scoop up the water to drink. The old people who have passed away now put their initials or marks on this tree, marks that cut straight down to express that ‘That person came here, he put his mark that he was here’. When they went hunting, they used to cook up their food and eat the boab nuts. In discussing why the tree may have died, Annie’s explanation was complex:

Our malajiy, this tree is like a malajiy – we say it’s a very powerful tree – it’s like an energy, it’s an energy. Energy that is interwoven between other powerful trees, stories, the river – all connect together, they connect to Yoongkoorookoo (rainbow serpent), everything is connected together through this energy.

The malajiy, the rai (spirit beings that live in Country – you can’t see them, but they see you) – together, they protect Country. ‘The story comes from their roots’. Explaining malajiy [as trees with special powers] Annie notes ‘each one gives us something. Some malajiy you can’t touch because they are dangerous, but others are powerful and give you different things from the land and the river’ – if you respect them and demonstrate that respect by tapping and talking to them. When they went fishing or hunting, Nyikina people would hit the tree with their boomerang and talk to it, asking ‘Give us some fish or lizard’. In talking about the connectedness of malajiy, Annie also indicates that human actions may have caused the death of the Windankooroo larrkarrdiy.

In the 1950s when Annie was still young there was a makari (in this case a bull shark) in the Liveringa billabong (Libirrirrbirrin) which had come in with the floods and stayed in the billabong. It is important to know that makari are special animals who are directly connected to Yoongkoorookoo (rainbow serpent). The children would play and swim in the water but it never hurt them. At this time, there was water in the billabong all year round. Then, one day in 1964, while the old people were gone, a new non-Indigenous station manager at Liveringa shot the makari, even though the old people had told him to leave it alone. After this time, the water in the billabong started to dry up. The kartiya (non-Indigenous person) did not know that the makari was the holder of the water. In 1969, the water had started to dry. Then, the malajiy near the billabong also started to die – one was a warimba (also known as the Kimberley Bauhinia or Jigal tree), Bauhinia cunninghamii (formerly Lysiphyllum cunninghamii)] and the other was jirral (Wingnut tree or Terminalia canescens). One malajiy tree near the billabong started to die and then the billabong went dry. The larrkarrdiy at Windankooroo was connected to the two malajiy trees and the makari at Libirrirrbirrin through energy that goes under the ground, it connects each tree and the shark, and they are connected to the [Fitzroy] River.

As part of this discussion, Indigenous authors were asked about seasonal markers, and they responded by saying that they saw many signs of changing climate. Everyone commented on the fact that the ‘knock’em down rains’ had stopped coming in recent years. These rains, so called because they flatten the head-high grass that grows during the wet season, open the way for the cold weather of the drier months. Nyikina authors present for the discussion, Annie, Jane and Kyra, were in agreement that the rainy season had been starting later. This has affected the distribution and availability of traditional resources and resource use. Freshwater crabs, mentioned in the context of the ceremony above, and which used to occur in Nyikina Country ‘you don’t see much anymore … not down this way … only up north’. Nabajara, the native cucumber, and the gooseberry were also getting harder to find. The konkerberry tree, which has fruit after the wet season, has not been flowering and fruiting in recent years and magabala, the bush banana, is generally scarce today, and those that did appear came later. Similarly, the flowering and fruiting that were signs forecasting seasonal change no longer accurately reflect these changes.

Despite such observations, it is difficult to link the death of the Windankooroo boab tree using ‘scientific’ measures of climate change. However, in scientific ways of knowing climate change is exclusively based on measurable changes in physical systems, whereas Indigenous Knowledge ‘encompasses not only empirical understandings and deductive thought, but also community know-how, practices and technology; social organization and institutions; and spirituality, rituals, rites and worldview’ (Nakashima et al. 2012, 30). Thus, Nyikina observations about the death of Windankooroo can be seen as relating to climate change, but climate change is itself viewed as part of a holistic web of interaction incorporating and linking the empirical physical environment and the spiritual environment. In the case of Windankooroo, this is described by the killing of the makari (bull shark) as well as to the acknowledgement that the sinking of a bore to irrigate feed crops for the cattle on Liveringa Station had likely caused a change in the water table and the water available to the boab roots.

Discussion and conclusion – future proofing against climate change

Although we were too late to document the Windankooroo larrkarrdiy while it was living, the memory of this tree and its story does live on for those who visited it. Remembering and sharing Windankooroo’s story is one mode of preserving its essence for future generations. Another form of documentation that is testament to its existence is the 3D model and visualisation that was made using photogrammetry. In their study of large old trees, Lindenmayer and Laurence (2017, 1435) argue that they are among the most ‘imperilled organisms on earth and that their protection demands innovative approaches to management and monitoring’. While they are no substitute for the living tree, digital methods of image capture, rendering and visualisation are useful tools to enable us to remember. They can produce a likeliness of a tree at a specific moment in its life cycle which enables a digital reconstruction, which may in turn be used for educational, communication and cultural purposes. As in other parts of the world (e.g. Barber, Maxwell, and Hemi 2014), photogrammetry is increasingly being utilised on CMTs within Australia (e.g. Buhrich and Murison 2020; Dardengo 2019) and our project is the first to deploy 3D photogrammetry on boab trees (Frederick, Andrews, et al. 2022; O’Connor et al. 2022).

Non-invasive documentation techniques like oral history, photography, and photogrammetry will prove valuable in efforts to mitigate losses and future proof against the impacts of climate change going forward. They also provide an opportunity to elicit traditional ecological knowledge around larrkarrdiy (boab trees) and its connection to the Kimberley environment. As we carry out our project to document culturally modified boab trees in the Kimberley, thanks to the boab tree at Windankooroo we are increasingly aware of their fragility.

While we are unlikely to determine with certainty a cause for the death of the boab Windankooroo, a number of possibilities have been raised. As with the boab’s identified vulnerabilities, all of these factors are inter-related with the effects of a climate that is changing rapidly. Each of the cultural explanations for why the tree Windankooroo may have died when it did, suggest anthropogenic causes. They also demonstrate a complex world view in which humans, animals, trees, water, and climate are delicately entwined and balanced ‘as participants in the flux of the world’ (Rose 2005, 33). Recalling an incident that took place several decades ago to explain the drying up of the billabong and the death of maladjiy trees, Nyikina co-author Annie Milgin’s recollection demonstrates how human actions may continue to have implications long into the future. The wrongful killing of the makari (bull shark) in the 1950s is why the soak dried up in 1969 and was linked with the death of the maladjiy larrkarrdiy (boab tree) in the 2020s.

Although it is thought that Adansonia gregorii are able to live for thousands of years, they are facing new challenges. Any increasing demise of boab trees is a matter of deep concern because unlike other species of CMT that have been preserved after their death, boab trees quickly decay and disappear. Just as archaeologists and heritage practitioners are increasingly embracing the need to seriously consider the effects of global warming on cultural heritage, it is also long past the time for them to consider the role that Indigenous knowledge may play in recognising, managing, mitigating and telling the stories of climate change impacts. As Rose (2005, 41) points out this traditional knowledge ‘will enable all of us to know what changes are occurring and to make decisions about how we may continue to live our lives in this vulnerable continent … this is knowledge that holds human beings accountable in the world because they are connected into the world’.

Acknowledgments

The authors wish to thank all of the Traditional Owners who participated in our 2021 and 2023 field seasons in Nyikina and Mangala Country. We also thank Ferran Antolin, the editor of this special issue, and two anonymous reviewers for their input.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This research was supported by an Australian Research Council Special Research Initiative [SR200200473] ‘Archives in Bark’ and under a Research Agreement with Walalakoo Aboriginal Corporation.