**3. Conservation problems and management issues previous to PNG**

Available information confirms the human presence on the islands from the Mesolithic to the Roman empire [6–11]. Throughout the Middle Ages, the islands depended on different monastic orders, maintaining a feudal regime. Between the 16th and 18th centuries, the islands maintained a system similar to the previous monastic regime, administered by the nobles of the towns located on the continent [12–14]. During this period the archipelagos will be witnesses and victims of numerous naval warlike conflicts against other nations, or against pirate invasions of various kinds [9], which led to the construction of fortifications and defensive bastions (batteries, barracks, arsenal, etc.).

During the 19th century, residents from the nearby coasts moved to the islands to attend to them and carry out various labors. The four archipelagos supported a population that ranged from 30 to 550 neighbors per island (depending on the island size). The insular inhabitants developed agriculture (potatoes, corn, vegetables), intense livestock activity, fishing, and shellfish. The islands were also used as a hunting ground, as well as different industries and facilities were installed (salting, lighthouses, etc.) in which the inhabitants of the islands worked [15–20].

During the 20th century, these infrastructures and facilities declined or were automated, as the quality of life in the continent was improved notably. This caused the archipelagos to gradually lose their resident population. The loss of population motivated the reduction (even total loss) of the crop areas due to the abandonment of cultivated lands, which were replaced by natural ecosystems (coastal heaths, sand dunes, etc.). This process was more evident in Sálvora and Cortegada islands, where agricultural activity was abandoned earlier, and this was not replaced by other actions, as happened in Cíes and Ons. In this way, Sálvora and Cortegada recovered their naturalness as they were subjected to natural dynamic processes, and the crop fields were replaced by dune habitats, coastal heaths, and native forests so that they currently have most of their occupied surface by natural ecosystems.

The depopulation of the islands progressed in parallel with growing activity in Cíes and Ons of the Spanish Forest Heritage (PFE the acronym in Spanish), created in 1935 but whose activity was definitely boosted from 1940, after the Spanish Civil War. The activity of the PFE focused for more than 20 years on the transformation of the natural habitats in the island territories (coastal heaths, fixed dunes, humid dune slacks) through productive afforestation [21–24] with exotic species (*Pinus* spp., *Eucalyptus* spp., *Acacia* spp.), many of which have the invasive capacity, following a methodology that was used in the rest of the Spanish coastal ecosystems [25]. So, natural communities of great biodiversity value were replaced by very low value synanthropic invasive formations that were potentially harmful to the surrounding ecosystems, although the high natural elements hosted by these islands had motivated them to be previously proposed in 1917 to be declared a "Notable Site" under the 1916 National Parks Law and the provisions that developed it [26], and there were also previous available scientific works that highlighted the relevant role of the insular natural environment [27, 28]. The activity of the PFE was especially relevant in Cíes, where it passed from a scenario characterized by natural herbaceous and shrub island habitats to a landscape in which exotic wooded formations occupy more than half of the surface [29]. In Ons, the afforestation was carried out in a smaller proportion, although it was also established at the expense of natural coastal habitats.

The afforestation of these island territories was used as an indoctrination measure of a country under an authoritarian regime in a context of political isolation and economic autarchy [30], to show and evaluate the "patriotic and lucrative work" that the PFE forestation works constituted. However, the high surface area that they reached in Cíes was a source of conflict with the few residents who still lived in the archipelagos, which led to them causing the uprooting of forest plants and even causing intentional fires with the purpose of destroying plantations. But the presence of inhabitants on the islands was in a regressive phase so that in the 1970s there were hardly any inhabitants left on the islands. Afforestation, on the contrary, was consolidated, so that even in the first Spanish vegetation cartographies, the forest plantations were already represented as the dominant coverage in the island territories [31]. The replacement of the PFE by Conservation Nature Institute (ICONA the acronym in Spanish) in 1971, abandoned the "lucrative" argument of forestation, but its vision of insular ecosystems was that of "arid, rugged, harsh, sterile and bare lands", and whose afforestation was necessary to improve its appearance so any visitor who arrived by sea to the Cíes could find a Spain "warm, fertile, forested, rich, industrial and peaceful". So, afforestation in this archipelago continued to be carried out by ICONA at the expense of natural habitats and still using exotic species, which is why they continued to win criticism from environmental sectors [17, 20, 32].

Starting in the 1960s, an unusual interest in tourism began to grow on the coast in general, and on the island territories in particular. The Cíes Islands played an important role in this new phenomenon, derived from the accelerated abandonment of its inhabitants and the growing promotion as a destination for touristic excursions. In this way, organized boat visits to the islands began to be promoted, which attracted numerous groups of people who uncontrollably accessed places of high ecological fragility, such as cliffs, fixed dunes, coastal heaths, rocky slopes, and humid dune slacks, causing a high negative impact on natural ecosystems due to the promotion of garbage, the production of fires due to uncontrolled bonfires, the erosion and loss of natural habitats, the collection of wild flora species, or the capture and nuisance of wild fauna population species.

In many of these cases, the high attraction that the Cíes islands had for the enjoyment and recreation of visitors, motivated an excessive profusion of free and uncontrolled camping, which was carried out in a completely unsustainable way. Due to the increasing interest in the island lands, a new trend began by the former inhabitants towards the sale of their few private properties. As a result of this process, the new buyers proceeded to build chalets, sheds, shacks, additions, etc., in an uncontrolled way and without any kind of permit or authorization, accompanied in many cases by the introduction of ornamental non-native plant species to decorate the properties of the new owners, although many of these species over time showed a high invasive potential, negatively affecting the surrounding natural ecosystems. So much so, that in the late 1970s it was possible to identify the presence of more than 300 uncontrolled shacks, and as many tents, dispersed throughout the island territory, without any type of environmental criteria or caution [17]. At the end of every summer season, a Dantesque spectacle of garbage and waste covered the islands: several boats were necessary to eliminate the kitchens, refrigerators and even ping-pong tables that were scattered throughout the island, as well as an intense smell of latrine invaded the area permanently.

In addition to the afforestation of PFE and ICONA, as well as uncontrolled buildings and public use, during the summers of the 1970s, some of the islands (the South Island of Cíes, mainly) were occupied by companies of Special Operational Commands (COES the acronym in Spanish) of the Spanish Army, who remained in the island territories performing survival practices. For this, they did not hesitate

to build cabins using trunks and branches that were cut down or removed from the trees present on the islands, as well as they fed on everything that could be edible for humans, eggs, and chickens of seabirds, mainly [20]).
