Study: Agricultural Intensification Hurts Olive Grove Productivity

Four years after its incep­tion, the Olivares Vivo project in Andalusia con­tin­ues to yield pos­i­tive results for the role of a bio­di­verse ecosys­tem in tra­di­tional groves.

According to the results of a new study pub­lished in the Journal of Applied Ecology by researchers from the University of Jaén, main­tain­ing veg­e­ta­tion cover and nat­ural areas in olive groves enhanced the diver­sity of species and the func­tions they per­form in crop­lands.

“In our study, we found that the diver­sity of species and the func­tions they per­form in the olive grove were neg­a­tively affected by the sim­pli­fi­ca­tion of the olive grove land­scape and the inten­sive man­age­ment of the plant cov­ers,” said lead researcher Rubén Tarifa, a doc­toral stu­dent in the university’s depart­ment of ani­mal and plant biol­ogy and ecol­ogy.

“The rare species were the most affected in this process,” he added.

According to the study, inten­sive agri­cul­tural prac­tices in olive groves usu­ally cause loss of bio­di­ver­sity by exert­ing intense pres­sure on plants, birds and insects, which are crit­i­cal for con­trol­ling com­mon olive tree pests.

“Not only is the loss of species dras­tic, but also the loss of func­tion­al­ity,” Tarifa said. ​“Furthermore, until now, it was unknown whether inten­sive agri­cul­tural prac­tices could be affect­ing the rarest species, tax­o­nom­i­cally and func­tion­ally, or on the con­trary, those that are more com­mon or dom­i­nant.”

“It is known that, in cer­tain com­mu­ni­ties, rare plants play a very impor­tant role within the com­mu­nity, sup­port­ing irre­place­able func­tions within the ecosys­tem,” he added. ​“For all these rea­sons, we pro­posed this study.”

Just like in pre­vi­ous stud­ies, the researchers found that agri­cul­tural inten­si­fi­ca­tion depleted veg­e­ta­tion cover with rare plants bear­ing the brunt of the pres­sure exerted by these types of farm­ing prac­tices.

Intensification was found to impact plants’ abil­ity to repro­duce through recur­rent plow­ing and the use of her­bi­cides. When her­bi­cides are used for pro­longed peri­ods, there is a risk of deplet­ing the seeds of cer­tain plants. This leads to those plants being removed from the land­scape, even when they are in dor­mant states.

In other instances, inten­si­fi­ca­tion indi­rectly impacts plants by inter­fer­ing with ani­mals that are crit­i­cal for the exis­tence of those plants, such as pol­li­na­tors. Since rare plants con­tribute to func­tional rich­ness dis­pro­por­tion­ately, their deple­tion usu­ally com­pro­mises the integrity of dif­fer­ent eco­log­i­cal processes.

During the study, researchers sam­pled plant cover from 40 olive groves in the provinces of Málaga, Jaén, Córdoba, Cádiz, Granada and Seville.

The researchers con­cluded that since weed cover plays an essen­tial role in sup­port­ing the fauna of per­ma­nent crop­lands, such as olive groves, and their pro­duc­tion, agri-envi­ron­men­tal schemes in these crop­lands should adopt low-inten­sity prac­tices that favor the func­tion­al­ity and diver­sity of ecosys­tems.

• Journal of Applied Ecology
• Oleorevista