For a general onlooker, the Australian Outback is nothing more than a bland empty void with low scrubs and bushes. But the kwongan bushland found in the south-west Australia has an unusually rich biodiversity even though subsisting on some of the world’s most infertile soils. In fact, the soil is so barren, that it is impossible to practice agriculture without adding tons of fertilizer and manure to improve the soil fertility.
To adapt to the infertile soils, plants develop phosphorus efficient leaves, which are tough, lasting many years. But below-ground, the story is all together different. Plant roots have all the known adaptation tricks in the text book, to capture the phosphorous they need.
In a new study published this week in Nature Plants, scientists from University of Montreal and University of Western Australia have discovered new diversified root adaptations to obtain nutrients from infertile soil by kwongan plants.
As Ben Turner, staff scientist at the Smithsonian Tropical Research Institute says, ”Plants cope with phosphorous scarcity in a similar way above-ground by making phosphorus efficient leaves. But below-ground they’re using many different strategies to obtain phosphorus, and the diversity of those strategies increases as soil phosphorus declines.”
Up until now, the belief in the scientific community was that, in extremely infertile soils like that found in kwongan, natural selection will favor a single, particularly efficient strategy for acquiring nutrients. But according to the new findings, the kwongan ecosystem contains such a wide variety of root modifications, that it almost covers all of the plant kingdom’s root adaptations on infertile soils.
The properties of soil change as soils age. Jurien Bay area in southwestern Australia, with its series of new-to-ancient soils, is one of the ideal places on earth to study how plants adapt as soils age. What the researchers observed was that, as the ecosystem aged, the number of plant species and the number of phosphorus acquisition strategies increased.
Researchers found that, some plants have symbiotic root relations with fungi like mycorrhizal, which spreads out like a net from plant roots, to capture nutrients. Another group of plant species exude organic compounds like carboxylates to ”mine” the soil for phosphorus. Some resort to parasitism and carnivory, to extract phosphorus from other organisms. But what surprised the researchers the most was, to see plants growing next to one another using different nutrient capture strategies and have just the same amount of success.
These discoveries about nutrient uptake by plants in poor soils are very important, as some day in future; it could help people to grow crops on degraded land everywhere.
Researchers believe that these findings in the kwongan region will help in protecting this unique biodiversity hotspot. As Dr. Graham Zemunik from The University of Western Australia points out, ”Ecosystems all around the world are being altered at an alarming rate. In order to protect biodiversity as best as we possibly can, we need to understand how these systems work. To achieve that goal, our study shows that it’s important to go beyond what’s immediately visible to study what nature has hidden below ground.”
Efforts have been there for some time to recognize this unique biodiversity rich kwongan ecosystem as an UNESCO World Heritage site.
