Clever little diggers, you

Over the years my mother has regularly sent me care packages - letters filled with newspaper clippings reporting newsworthy scientific discoveries. I find them all interesting, but one from her most recent mailing particularly captured my imagination - Tiny digger turns deserts into gardens. The article reports on the findings of University of NSW PhD student, Alex James, who has monitored the results of a combined eradication/reintroduction program at a fenced reserve in the heart of arid Australia. Feral dogs, cats, rabbits, and foxes had been removed while native burrowing bettongs and greater bilbies had been reintroduced. James's study has shown that, "Despite its diminutive size, the humble bilby can dig a desert back to life". Plant and animal life is flourishing again in the study area.

The report highlights a couple of fundamental creation truths. First, it shows yet again that every one of earth's almost endless eco-systems will, given half a chance, spring back to life. Through over-grazing, mining, the introduction of exotic species. etc, etc, etc. we human beings have shockingly degraded every landscape we have set foot on and axe to. Few of us have the slightest notion of just how beautiful, productive, and "alive" virtually every nook and cranny of this planet - even its arid zones - used to be. Study after study is showing that intelligent, nurturing land management practices will produce stupendous improvements in the raw beauty and biodiversity - not to mention productivity - of all but the harshest of places. (Even they play a role in maintaining the all-important steady state of nature's biogeochemical systems.) Even so simple a measure as reintroducing the wolf has breathed new life into Yellowstone National Park's wheezing natural economy.

And the second great creation truth? Just as a child discovers wondrous things when he pulls apart a clock or wind-up toy to see how it works, a little tinkering with the cogs and springs that make ecosystems tick inevitably rewards investigators with numerous surprises. Who would ever have guessed that a small mammal could make such a difference for the good simply by slavishly following its instinct to shovel dirt? James discovered that when bilbies dig for their dailybread they carve out eight-inch-deep (20 centimeter), saucer-wide potholes in the poor soil that trap blowing twigs and leaves and hold the rare rainwater, creating a tiny oasis of nutrient-rich, moist compost. Bilby diggings contain up to twice the levels of nitrogen and carbon nutrients as undisturbed soil, turning the potholes

into seedling nurseries. Voila. Deserts begin to bloom and buzz.

To be honest, now, James was probably expecting exactly that result. In recent decades, and particularly in the past ten years, ecologists have become more and more aware of the health-giving role played in many ecosystems by "bioturbation" - the digging and mixing of soils by mammals, birds, reptiles, worms, ants and a whole range of unusual suspects. Bioturbators "make the topsoil more porous, break up and distribute organic matter, bring material from the deeper parts of the profile towards the surface, add nutrients, and balance the activities of micro-organisms that are performing micro-bioturbations".¹ Who would ever have thought?! Even the mere scratching of soil surfaces by mammals and birds can play a significant role by turning under organic matter and by making the soil more absorbent.

Ants in the sugar bowl or falling onto your bed from the light fixture above (as is happening to us) may drive you to distraction; ants in the vegetable garden should make you jump with joy (as well as with irritation). Think of the digging and dunging they are doing.

A search on Google Scholar lists over 33,000 journal articles that talk about bioturbation on land and in the sea; almost half have been published in the past decade. As one article summed it up recently, "There is growing recognition among ecologists that ecosystem engineers play important roles in creating habitat for other species.", both plant and animal. ² The same article reports that, for example, lizard abundance was two to four times higher in areas where burrowing prairie dogs and kangaroo rats create tunnels and mounds than in adjacent areas where these mammals had been eliminated. Another article in the same journal attests to the rejuvenating role played by digging badgers in degraded shrub-steppe zones in overgrazed parts of western USA, stating that, "mounds may be important sites for recovery of indigenous shrub-steppe plant species." ³

Yes, He's done it again. The mind of God knows no limits to its capacity for creative thinking. Whatever you do, please don't even begin to entertain the idea of giving credit for engineering ants and rodents or for plant-nurturing pothole oases to an unstable, infinitely dense singularity that just happened to explode. Common sense surely tells us such a proposition is nuts.

¹ Mary White, Earth Alive, p. 77

² Davidson and others, Engineering rodents create key habitat for lizards, Journal of Arid Environments, 72 (2008) 2142-2149

³ Eldridge & Whitford, Badger (Taxidea taxus) disturbances increase soil heterogeneity in a degraded shrub-steppe ecosystem, 73 (2009) 66-73