Race against time to stop Malaga's pine trees from dying: these are the causes

For more than a year hundreds of pine trees have been dying within a matter of a few days. This is not an issue exclusive to Malaga city. Not even in the province. Nevertheless, it is of great concern to Malaga city council, which has teamed up with scientists from the University of Cordoba in a race against the clock to find solutions. The causes are attributed to a complex mix of interrelated factors, with drought and insects at the heart of it, but they are not the only culprits.

This Thursday SUR saw how workers from Perica (the company contracted to service all of Malaga city's outlying parks) were busy removing dead trees. On this particular day they were in the area around the small road that connects the Seminario with Conde Ureña. It is compulsory to remove such trees so as not to add combustible materials to the forest floor, to clean up the woodland and also to avoid accidents in places frequented by walkers, families and the few cars that use this minor road.

For this reason, a few months ago the council department responsible for the environment and sustainability turned to the School of Agricultural and Forestry Engineers at the University of Cordoba to set up a collaborative agreement that called on their expertise. This specialist assistance was agreed at a cost of 12,000 euros.

Ángel Lora, lecturer in the Department of Forestry Engineering, talked to SUR and explained that last week the scientific team had just finished the sampling. Some of the tree stumps left show the marks where they collected such samples. The fieldwork began before summer and continued over the last few weeks after a summer break.

Lora is cautious about their findings to date but was prepared to offer some clues while waiting for the different types of samples to be processed. One of the first causes goes back decades: reforestation with specimens planted very close together and thus reaching very high numbers - for example in El Morlaco, some 10,000 saplings per hectare.

At this point the suggestion is to move gradually towards a better version of silviculture (forest management) by creating clearings, thinning out trees, even culling certain trees and other procedures. Selecting individual trees to retain would be another suggestion.

In addition to the aforementioned Morlaco and Monte Victoria, the other sites on which this work is focused are at Gibralfaro and San Antón.

"A second factor is the shoddy land, very poor quality soil, all sloping.... These are already tricky soils to handle, so if we add competition between trees...", said Lora.

Drought and high temperatures are taking their toll on the pines and weakening them further. The soil is very dry and the roots are shallow. "Pines are physiologically better equipped to compete with the cold."

"The mass of trees has been weakened and that's where the opportunists come in," he explained. They are a whole swathe of scolytid beetles. We still have to determine which ones specifically are at work here. We are processing them," he explained. In common parlance these beetles are known as 'barrenillos' (borers) and they are xylophagous, they simply eat the dry wood and degrade the tree in record time. The tops of the trees have increasingly large brown spots that contrast with the green of the healthy ones as the beetles munch their way through.

At the moment, it seems to be ruled out that these insects, of which there are more than 6,000 species worldwide, are carriers for nematodes (eelworms) or grubs, but this is something that needs to be investigated further.

This expert warns of the proliferation of these bugs, which often take refuge inside felled stumps. It would be important to eliminate them, but this is neither easy nor cheap.

Another idea he proffers is something that Malaga council has been working on for some time now in its ambitious reforestation policy: switching to carob, cypress, wild olive and other Mediterranean species.

In any case, he advises that work remains to be done and that for the moment what exists is only a general framework going forward. He makes it clear that each of the areas has its own peculiarities - for example, San Antón offers good possibilities for a more Mediterranean woodland.

While the opportunistic pine-boring beetles are wreaking havoc, the council's environmental and sustainability specialists are working tirelessly. Some areas have been set aside for weekly watering to check if these specimens fare better than the parched trees.

It is this council department that maintains the latest data on progress. As of some months ago 1,000 dry specimens had been removed. But this figure must now be considerably higher as more than 4.5 million square metres of forest are registered in the city.

Regarding the aforementioned test of watering a plot of about a thousand square metres in Gibralfaro (the hill behind the city centre) once a week, the aforementioned sources point out that the result is that they are not drying out nor dying out, so everything points to the lack of rainfall as the main cause.