The traditional olive grove, an oasis of biodiversity

When we imagine the habitat of wild animals, we usually associate them with idyllic forests and lush thickets, populated by countless native species and intricate ecological relationships. We don't get the same idea when we think of a wheat field, a vineyard or some almond trees: monospecific crops, periodically tilled and with frequent human manipulation. But is this really the case?

The study and its results

In an area of the Campo de Montiel Albacetense, we analyzed how the elements that shape the landscape influenced the presence of carnivorous mammal species (Arenas, 2012).

After convenient field censuses and landscape studies using GIS, “fauna-habitat” models were obtained that established the relationships between the landscape and carnivorous mammals. The expected result was to find an association between this group of animals and natural vegetation environments such as forests and scrub. However, this was not the case. The results were very diverse with the different species, but none showed a preference for natural forests and scrub. On the other hand, the environment that did stand out was the olive grove: the wild cat (Felix silvestris) and the weasel (Mustela nivalis) were associated with the olive grove environment.

The importance of olive groves for these two species

Faced with this interesting result, new questions were raised: why is this happening? , what does the olive grove offer to these species? , how important is this result for the olive grove itself? To answer these questions, we will analyze how olive groves could meet the most basic needs of these animals: shelter and food and what does the presence of these species mean for olive groves.

In the case of the weasel, the olive grove present in the study area, mostly centuries-old and divided into small plots, would offer a multitude of shelters between the hollows of the thick trunks and the boundaries of piled stones. In terms of food resources, the weasel is a strictly carnivorous animal specialized in capturing micromammals such as the brown mouse (Mus spretus) or the scareto dormouse (Eliomys quercinus) who in turn find food and shelter in the olive grove (Muñoz-Cobo & Montesino, 2005; Tarjuelo, 2010).

Unlike the weasel, the wildcat is too big to find good protection in the olive grove for shelter. Closed natural vegetation in the form of scrub, groves or forest must perform this function, however it does not need large areas of these formations, as the result of the study would have been different. In this regard, what is known as a “mosaic landscape” and which is typical of the traditional olive groves of Campo de Montiel, seems to be fixed with the small patches of natural vegetation present between borders, slopes, streams, etc. Therefore, it must be the trophic resources that the olive grove can offer that attract this species.

The wild cat is capable of preying on a wide range of prey, including small and medium-sized mammals, birds, reptiles, insects, etc. (García, 2004; Lozano, 2009). The olive grove can be home to a multitude of these possible prey: micromammals such as those mentioned above; the rabbit (Orictolagus cuniculus) can be very abundant, even causing damage to this crop (Pastor, 2007; Arques et al., 2010); for the Iberian hare (Lepus granatensis) olive groves constitute a key habitat in Mediterranean environments and are where they reach their highest densities (Duarte, 2000); insectivorous birds such as those of the Parid family use olive groves to feed and nest (Muñoz-Cobo & Montesino, 2005); for others such as those of the genus Turdus The olive grove is of vital importance during migration and wintering, providing shelter and food in the form of olives (Soler) et al., 1988; González-Solís & Ruiz, 1990); in certain places, a positive correlation has been observed between densities of red partridge (Alectoris rufa) and olive grove cover (Díaz-Espejo, 2004).

The importance of these two species for olive groves

We have already seen what the olive grove means for the weasel and the wild cat, but how important is the presence of these species for the olive grove itself? The mere fact that strict carnivorous species such as these inhabit this environment is already an indication of biodiversity, because being in the upper links of the food chain, it informs us that the lowest and intermediate links must be well represented by a multitude of species and all together they form a ecosystem.

In addition, these carnivorous species would have a control function over other animals that in their absence could cause serious damage to olive groves and therefore to crops, such as voles or rabbits (Lucena et al., 2017). And this is where an important element of this “ecosystem” appears, because without it it would not exist: the human being. The olive grove is one of the oldest crops in the world, originating more than 6000 years ago. Phoenicians, Romans and Arabs promoted their expansion across the Iberian Peninsula and their exploitation has continued uninterrupted to the present (Lucena et al. 2017).

Nowadays, the traditional olive grove is in decline. Among the causes would be the drop in prices at the source of oil, the intensification of modern olive farms and the strategies of the Common Agricultural Policy (CAP) (López, 2019), but this topic would be enough for another post. Little by little, the traditional olive grove, an example of sustainability, is being left abandoned or uprooted to adorn gazebos and gardens, losing a crop that for centuries has played a very important social, economic and environmental role.

Bibliography

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