La seed dispersal on Mount Teide is going through a delicate moment after centuries of human impact. A recent analysis reveals that the network that allows plants to colonize new spaces and maintain their genetic diversity has weakened noticeably, compromising the natural regeneration of the high mountain ecosystem.
According to an investigation by IPNA-CSIC published in the magazine Global Ecology and Conservation, the park has lost seven out of ten links between frugivorous fauna and flora with respect to a potential scenario reconstructed from evidence in other habitats. Even so, there is a wide margin for recovery: About 90% of plausible interactions involve species that are still present.
What's happening with the scatternet
The study finds that today only persist 15 interactions across six species of plants y seven dispersers, in front of 48 estimated as possible. This decline, which is equivalent to an approximate loss of 70%, leaving a more fragile network with less capacity to respond to disturbances.
The underlying cause accumulates 2.000 years of human pressure: logging and burning of the ancient cedar forest, overexploitation and habitat degradation. As a result, the system shows signs of incomplete functioning, with key ecological processes slowed or reduced.
Keystone species and dispersers
In this framework, the Canary cedar (Juniperus cedrus) emerges as a structuring species: its fruits feed birds and lizards and multiply connections in the ecological network, making it easier for seeds to reach new enclaves.
Today, much of the dispersion falls on two main and complementary actors: the white-capped blackbird (Turdus torquatus), decisive during its wintering to move seeds to long distance, as well as the blight lizard (Gallotia galloti), effective to short distanceThis dependence on a few dispersers makes the system more vulnerable.
Other birds with dispersing potential, such as the common blackbird (Turdus merula) and the robin (Erithacus superbus), are today very scarce in the park. Their return as effective dispersers would depend on habitat improvements and the recovery of the cedral.
The situation of the flora is also worrying: four of the six species with fleshy fruits of Teide are threatened, including endemic species such as summit benzomia (Bencomia exstipulata), the morality (Rhamnus integrifolia) And Rosa Cañadas-Teydensis (Rosa cañadas-teydensis), proposed by experts for its critically endangered classification.
In the case of canary cedar, researchers point out that they survive around 1.250 copies, many in cliffs and inaccessible areas, which makes it difficult for seeds reach suitable microhabitats without the help of abundant dispersers.
Climate change and phenological imbalances
Global warming adds an additional risk: phenological mismatchIf the fruiting of the plants does not coincide with the presence of dispersers, the efficiency of the process drops just when the ecosystem needs it most.
This scenario increases the probability of functional collapse of the network, in the form of cascading extinctions of interactions, although individual species continue to exist for some time.
What can be done
The recommendations converge in restore the cedar, improve the habitat quality and promote the natural dispersion. Among the priority actions are: repopulations with seed bombs, increase in water resources for frugivores and continuous monitoring of their populations.
To accelerate recovery, it is proposed improve connectivity between plant nuclei and beef up to the native dispersers that still persist, so that they return weave the network of interactions that supports the system.
The authors emphasize that if anthropogenic pressures are reduced and processes are rehabilitated, it could recover up to a 90% of potential interactions, since the protagonists of these links are still present, although at low densities.
In parallel, management measures are moving forward. A project of recovery of the cedral driven by the administration (through Gesplan) with a budget of 1.116.800 Euros and execution horizon up to February 2026, oriented to reintroduce plants and stabilize populations.
In addition, experts urge to review uses that add pressure - such as certain sports, apiculture or the high influx—to balance them with the conservation objectives of the National Park.
How the evidence was obtained
The team integrated 2020–2021 samplings and previous records with a reconstruction of interactions observed in other systems, generating a potential network with which to compare the current one. The results were published in Global Ecology and Conservation.
An encouraging fact is that no extinctions have yet been recorded of plants with fleshy fruits in the park, which represents a window of opportunity to act with margin, update assessments and consolidate restoration before reaching points of no return.
The general picture is clear: Teide preserves the wicker to rebuild its dispersal network if the cedar forest, key dispersers such as the white-capped blackbird and the lizard Tizon, and the pressures that have depleted the ecosystem for centuries are relieved.
