Agrobiodiversity Agro, bio, what? – Why is the diversity of agriculture important?
Diversity is an important thing. Maybe we have partly understood it. But do we really understand why it is so important? Of course, it’s nice to have lots of different coloured butterflies and interesting animals living around us, and of course we should protect them, but this story is about much more.
Biodiversity is our life insurance.
Agrobiodiversity – that is, the diversity of our agricultural plants and animals – means our future meat and potatoes, and it is a key element of our food security. This is the message of a scientific publication issued in 20191, which revealed that the stability and the predictability of yields can be significantly enhanced through increasing agrobiodiversity. In countries and regions where food production is based on growing multiple plant species, a drastic reduction in the total national yield (meaning a loss exceeding 25%) occurs only rarely.
Agrobiodiversity and yield security
This study, which was done by an international research team, divided the Earth into 22 subcontinental agricultural regions, and investigated how the species composition of the cultivated plants, the ratio of their production areas and their average yields (in relation to their total calorific value) has changed at regional and global level over the last 50 years.
According to the results, the diversity of the cultivated plants can stabilize the yearly yield level to such an extent that it counterbalances the yield-related negative impacts of the fluctuating yearly precipitation patterns.
Consequently, by diversifying the species composition of our cultivated plants, we can increase yield stability.
How agrobiodiversity has changed over the last 50 years
Although it may seem surprising, the publication also revealed that the diversity of agricultural production has systematically increased at regional level over the last 50 years. This is due to the spread of large-scale agricultural practices from the 1980s resulting in the large-scale production of certain plant species in areas and regions where formerly they had not been produced traditionally, or they could not be grown due to technological difficulties. However, this surprising intensification driven regional diversification ended in the 1990s, and differences started to decrease among the regions besides the development of the current trend of uniform regions. Regional differences started to disappear as a result of just a few species dominating production.
Even though diversity has increased at the regional level over the last 50 years, large scale farms, which dominate agricultural production, have become more homogenous, irrespective of the continent they are on. As a result of this, diversity has significantly decreased at global level.
For example, at the moment 93 plant species are grown in North America compared to the 80 species value of the 1960s2. However, increased diversity caused by the higher number of cultivated species could not counterbalance the impact that half (!) of our arable land is used to produce just four species at global level. The four dominant plant species are wheat, maize, rice and soybeans. The other half of our arable land is planted with the “remaining” 152 food crops.
In addition, the largest producers usually grow only one genotype (variety/hybrid) of one species, sometimes even on thousands of hectares. For example, in North-America 50% of maize production is covered by only six genotypes. It is a shocking uniformity.
The consequences of decreasing agrobiodiversity
Uniformity – that is the decrease of diversity – may seem positive at first glance. It can increase efficiency and profitability of agriculture. However, advantages never come alone.
From an ecological point of view, agricultural systems dominated by only a few species or varieties are extremely vulnerable. A good example is the global banana production threatened seriously by a new race of Fusarium wilt. Although there are more than 1,000 banana varieties available worldwide, 47% of banana production is based on a single variety called Cavendish.3
But diversity and efficiency are not mutually exclusive. However, currently we tend to choose the easier, and more comfortable, way instead of standing up for diversity. Well, it is not worth it, especially in the long run, because due to the growing human population our food demand is also continuously on the rise, while our climate – partially due to industrial agriculture4 – is rapidly changing. Diversity is our only insurance against something unexpected happening. If something happens, and we have diversity, we also have the chance to replace the lost elements with some other ones.
We can probably live without bananas in the future, but losing the diversity of wheat, rice, maize and soybeans will put us in great trouble.
So, diversity is crucial. We also know that the different kinds of diversity – agro, agrobio, genetic, species level and ecological level – need to be conserved.
If we totally lose diversity, we are also lost. And sooner than you might think…
So, let us save what we can still save. Eat locally produced food, support farmers with diversified and sustainable production, and always eat slightly different things.
Biodiversity has three primary levels: genetic diversity, species level and ecological diversity. Biodiversity as a whole is defined by these three complementary levels.
- Genetic diversity means the first level including the variability of genes.
- The second level is taxonomic diversity, meaning the richness of the species. This is the most easily understandable tangible level of biodiversity. Species level agrobiodiversity – calculated from the number of species and the size of their production areas at a given period of time – which is covered by the publication1 also belongs to here.
- Ecological diversity is the largest scale and the most complex level of biodiversity, defining variation at the ecosystem level. The largest ecosystem is the Earth itself.
1: Martin AR, Cadotte MW, Isaac ME, Milla R, Vile D, Violle C (2019) Regional and global shifts in crop diversity through the Anthropocene. PLoS ONE 14(2): e0209788. https://doi.org/10.1371/journal.pone.0209788
2: University of Toronto. “A very small number of crops are dominating globally: That’s bad news for sustainable agriculture.” ScienceDaily. ScienceDaily, 6 February 2019. www.sciencedaily.com/releases/2019/02/190206161446.htm