Ginkgo enigma

There are many enigmatic plants out there in addition to the boab. One is the ginkgo (Ginkgo biloba).  It is such a different tree, biologically unique, really deserving of the moniker living fossil.  Millions of years ago it grew all across the world, and today people are familiar with it as a common street and park tree in virtually all temperate climates zones, yet its presence in “the wild” is limited to a few mountains in China – and the wildness of these populations is disputed.   It went extinct nearly everywhere, only to be brought back to life – and proliferated – due to its association with people who cultivated it and celebrated it.  

A political ecology of weeds

How do plants that move and spread across landscapes become branded as weeds and thereby objects of contention and control? In a chapter recently published in the International Handbook of Political Ecology, Priya Rangan and I outline a political ecology approach that builds on a Lefebvrian understanding of the production of space, identifying three scalar moments that make plants into ‘weeds’ in different spatial contexts and landscapes.

People and the dispersal of baobabs around the Indian Ocean

[reposted from christiankull.net]

The baobab, that iconic, majestic, and grotesquely massive roots-in-the-sky tree, teaches us something surprising about “nature”.  It demonstrates that what appears to be “natural” has been – for millennia and millennia – also fundamentally “social”, for people have been important dispersal agents of these trees.  Researchers like Chris Duvall and Jean-Michel Leong Pock Tsy have shown this for the African baobabs.[1,2]  Our recently completed research project, led by Priya Rangan, demonstrates this in multiple ways around the Indian Ocean.  Baobabs are such useful and remarkable trees [3], it is hardly difficult to imagine people not picking up the hard but pleasantly light and fuzzy fruit pods and walking with them.

A young baobab near an Aboriginal rock art site (photo: CKull)

One part of our project looked at the single species of baobabs found in Australia: Adansonia gregorii, called boab. It grows in the Kimberley region in the northwestern part of the continent.  In a study just published in PLoS ONE [4], we combine evidence from baobab genetics [5] and Australian Aboriginal languages to show that humans have been the primary agents of baobab dispersal.  In particular, we reveal their crucial role in dispersing baobabs inland from now-submerged areas of northwest Australia during the dramatic sea-level rises at the end of the last glaciation.  (See also Priya’s blog about the study)

A further question is how the baobabs arrived in Australia in the first place.  Oceanic dispersal via seed pods floating in currents, several million years ago, remains the most plausible explanation, as our collaborator David Baum has shown [6].  Yet, another one of our baobab collaborators (and veritable Renaissance man) Jack Pettigrew advances an interesting speculative argument about a possible human role in transporting the baobabs, building on evidence from rock art in the Kimberley

Trip report: lantana, people, and wildlife in southern India

Recently, several of the Trans-Plants collaborators met in Bangalore on a scoping trip for our “indigenous people and weeds” project.  We each took home different impressions from the trip and report on them here.  This first instalment is by Christian Kull

The thorny bush Lantana camara, with its attractive pink, yellow, and orange flowerlets, covers vast areas of forest understory, fallow lands, and hedges in the hilly mountains fringing the southern end of Karnataka state, India. These upland areas are also home to several marginalized cultural groups (‘scheduled tribes’, or ‘indigenous people’) as well as a diversity of wildlife – elephants, tigers, bears, gaur, three kinds of deer, monkeys, boars, wild dogs, leopards. On our recent scoping trip to the Biligiri Ranganaswamy Hills some four hour south of Bangalore, we discovered that there were at least three ways one could talk about the lantana situation, each following familiar tropes: as a story of invasion, of dispossession, or of creative redemption.

Spotted deer (chital) surrounded by lantana

Reflections on invasion biology

By Christian Kull

Invasion biology has been a remarkably active branch of the life sciences in the past two decades. My itinerary first crossed this field when I noticed, at the time of my move to Melbourne, that the ‘precious’ mimosas (acacias, wattles) of the Madagascar highlands were called ‘green cancer’ in South Africa, and in both cases were introduced from Australia. It was quite surprising to discover that this shrubby tree, so appreciated by Malagasy farmers (as a resource) and environmental managers (as ‘regreening’ barren lands), was seen so negatively across the Mozambique Channel. This observation led to a research program that (1) opened a window for me to learn about and consider the field of invasion biology, and (2), serendipitously, to collaboration with ecologist Jacques Tassin at the French research institute Cirad. I comment on some of the recent fruits of both in this blog.

The South African approach to alien plants. Cartoon from environmental education material collected in 2006 (thanks to Rémy Kinna).