Farming: biodiversity’s biggest enemy, and its greatest ally

 

Figure 1: agriculture is associated with land clearing, but we can change that!

Figure 1: agriculture is associated with land clearing, but we can change that!

Global biodiversity is under siege faster today than at any time in Earth’s history. As we rush to expand our farms and feed 9 billion people by 2050, we’re pushing Earth’s planetary boundaries to dangerous levels well beyond their sustainable limits.

Covering nearly 1/3 of Earth’s surface, agriculture feeds 90% of the world’s population on just 15 plant species and 8 animal species, and is Australia’s single biggest contributor to habitat loss.

Biodiversity be damned.

Yet, despite this, modern agriculture is now the key to biodiversity conservation.

 

How could farming possibly be good for biodiversity after all that!?

I’ll admit, those stats above look rather bleak. But, hear me out here!

Let’s start by looking at why agriculture is so bad for biodiversity.

Agriculture needs a lot of land, so people clear a lot of land to grow their crops and feed animals.

However, doing this causes has a disproportionately negative affect on biodiversity. Let’s look at why that is in Figure 2. In a relatively intact environment, some habitat loss makes minimal difference to the rate of species loss. But, if we look at the species loss between (a) and (b) in Figure 2, habitat loss progressively accelerates the rate of species loss disproportionately at <30% of remaining habitat area. This holds true for pretty much all scales: over several kilometres, or just a few hundred.

This is because, as Andren explains, when remaining habitat drops to 30-40%, biodiversity becomes increasingly affected by declining patch size and increasing isolation.

Figure 2: notice the accelerating rate of species loss between (a) and (b)

Figure 2: notice the accelerating rate of species loss between (a) and (b)

 

So, how can farmers help?

Agriculture and farmers can help address two major components of habitat loss: cumulative habitat, and habitat connectivity.

Whereas cumulative habitat refers to the total amount of habitat in a given range, habitat connectivity refers to how easily species can move between two patches of habitat. For example, if a patch is too isolated for species to move into, then it is not interconnected and therefore does not contribute to the cumulative habitat.

This is where farmers and agriculture comes in.

By creating patches of habitat on owners’ farms, they can create what is known as a “nature corridor,” which can essentially create a stepping stone between two isolated habitats.

Benefitting many invertebrates and terrestrial animals as well as birds, building these patches of habitat offers agriculture a way of contributing greatly to conservation.

This principle is demonstrated in figure 3.

Figure 3: farms can improve biodiversity by serving as a stepping stone

Figure 3: farms can improve biodiversity by serving as a stepping stone

Therefore, by creating even small patches of habitat on your farm, you can markedly contribute to biodiversity conservation. What’s more, you can both receive a grant from the government to assist with this, and reap associated financial benefits for your farm in the form of improved productivity.

Putting theory to practice

To demonstrate these principles in action, I returned to my family farm to undertake rehabilitation from the 7th to the 10th of September (2016).

Located in Largs, NSW, opposite the oldest continually running primary school in Australia, this site has been used for agriculture for about 175 years. The farm was originally used to grow vegetables before transitioning to a dairy farm during the 1900’s and today an organic hobby farm producing chickens, sheep, pigs, and up to 20 head of cattle.

So, it’s fair to say the land has had a long history of land clearing and habitat loss.

To address this, I focused my rehabilitation efforts on the areas marked in blue in figure 4. This was area was chosen because it represents a wetland and significant hill which may erode into the wetland. If this occurs, significant aquatic habitat could be lost. Therefore, to protect the wetland, the hill also needs to be rehabilitated.

Figure 4: my family farm in Largs, NSW.

Figure 4: my family farm in Largs, NSW.

Focusing on the areas market in blue, I aimed to rehabilitate habitat by planting a lower, mid, and upper storey of native species. This was done because it creates a balanced ecosystem which can be of use to both large and small animals (our free range chickens will love scratching around in the understorey!).

To recreate the habitat, I focused on planting a mixture of species native to the Lower Hunter and in particular wetland areas. For the lower storey, I focused on planting sedges and rushes as these plants work well in wetland areas and are excellent habitat for small aquatic birds like the Water Hen (Gallinula chloropus).

Rehabilitation can also have great side benefits for farm resources as well. For example, the strategic planting of rushes helps discourage cows from coming too close to the banks of the dam and eroding its edges (a costly exercise to repair).

To recreate the mid storey on the hillside, I focused on planting native species such as Tea Trees (Melaleuca alternifolia) and Bottle Brushes (Callistemon), amongst others. Creation of this layer was done to encourage native bees and birds with the flowers of these trees. This is crucial to improving pollination in the region.

The upper storey on the hillside was populated with trees like the Blue Gum (Eucalyptus globulus) and Turpentine (Syncarpia glomulifera). To add to farm resources, I also added White Mahogany (Eucalyptus acmenoids) because it makes excellent timber for making fence posts in the future- thereby creating farm forestry resources! Just one of the many side benefits of habitat rehabilitation.

 

Closing thoughts

Overall the work was very easy, with great benefits for the farm and biodiversity. Our chooks have a new scratching ground, cows have shelter in the summer, the banks of our dams are more protected, and in the future we can use the white mahogany for fence posts.

Moreover, farms are also an ideal candidate for maximum biodiversity returns on investment. This is because, as Philip Gibbons points out, rehabilitation in highly degraded sites has the greatest biodiversity returns. This concept is explained in figure 5. Investing in sites which have already been rehabilitated will always have diminishing returns. Therefore, we can be sure that we got the best bang for our buck in both farm resources and biodiversity!

Improved biodiversity, increased farm assets, happy chooks, and possibly even increased land value caused by improving eco-assets.

What’s not to love?

Figure 5: getting the best bang for your buck. Investing in previously unmanaged sites gives better biodiversity return on investment than managed sites

Figure 5: getting the best bang for your buck. Investing in previously unmanaged sites gives better biodiversity return on investment than managed sites

 

By Kieran Hancock (u5584329)

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About Biodiversity Conservation Blog

I am an Associate Professor at The Australian National University and convene a (very awesome) course called Biodiversity Conservation. Myself and students in the course contribute to this blog.
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One Response to Farming: biodiversity’s biggest enemy, and its greatest ally

  1. Nicely conceptualised Kieran. Would be good to see a photo of the site you replanted. Phil

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