A before and after in the upper basin of the Pirón River. Sierra de Guadarrama, Segovia.

 

The Pirón River originates in the Sierra de Guadarrama mountain range at the Fuente del Mojón spring, at the foot of the Malagosto mountain pass, in the province of Segovia, and flows into the Cega River in the Valladolid municipality of Cogeces de Íscar. It passes through the municipalities of Santo Domingo de Pirón and Basardilla, where it is dammed in its mountain section at the Aprisqueras Reservoir. The upper basin that feeds the reservoir is made up of the public utility mountains No. 253 “Aprisqueras”, No. 254 “Majalperro” and the “Arroyo de las Corzas” mountain, which was reforested by the forestry administration.

The Scots pine (Pinus sylvestris) forests, which once dominated these mountain landscapes, are less resilient to grazing, uncontrolled logging, or fire, unlike the Pyrenean oak (Quercus pyrenaica) woodlands, which have a high capacity for stump and root regrowth. From the Celtiberian settlements to modern times, livestock farming, primarily sheep and goats, was the main form of subsistence for the inhabitants of these slopes. This continuous activity over time progressively transformed the landscape, to the detriment of the mid- and high-mountain pine forests.

In the 1964 photo, you can see the result of this ancestral pastoral culture, which is reflected in numerous place names of different sites and infrastructures, such as drovers' roads and livestock trails, shearing stations, ranches, washing places, fulling mills, sheepfolds, and countless constructions and trades mainly linked to sheep farming. The decline of the traditional agricultural system and the massive migration from the countryside to the city led to a drastic decrease in sheep farming. In the photo, you can observe houses that accommodated workers, and we also see cattle farming, dedicated to milk production and maintaining the draft oxen used in the reforestation process. We can also locate the buildings of the forest nursery in the photo, where plants were produced. The reforestation works would last about 20 years.

In the lower left quadrant of the photo, you can see the state of Mount "Mata Pirón," a degraded coppice of Pyrenean oak (Quercus pyrenaica) that has survived to this day due to the value of its firewood and hunting, combined with its ownership type: a mountain of changing ownership that served as a recreational area for the royal houses that have succeeded each other throughout the history of Spain. First belonging to the Community of City and Land of Segovia and then to the Crown Estate, it passed into private hands in the second half of the 19th century.

In the photo of the current state, we can observe how these oak woodlands have been evolving favorably due to a beneficial silviculture, based on thinning, to guide it towards a structural high forest. The reforestation was carried out with the native Scots pine (Pinus sylvestris) and began in the late 1950s. The objective was a hydrological-forestry restoration financed by the State and aimed at providing supplementary employment to workers who still lived from the traditional agricultural system.

The result is assessable from many points of view. The installation and permanence over time of a tree canopy generates a positive change in soil conditions. In addition to buffering the effect of unfavorable surface processes, such as erosion or rapid mineralization of organic matter, the dynamics of their root systems increase the edaphic volume and improve their physical and chemical properties, as a result of the deep incorporation of organic matter, which translates into more diverse and resilient ecological conditions.

The small Aprisqueras reservoir basin, which barely exceeds eleven hundred hectares and encompasses these forest systems, plays an important and positive effect on the hydrological cycle. Currently, the forests of this basin have about 170,000 m³ with bark (w.b.) of wood with a current annual growth of 6,800 m³ w.b./year and approximately 40,000 m³ w.b. have been extracted during the last 20 years from this sustainable, renewable, and biodegradable natural resource with hardly any consumption of external inputs, through improvement and stability cuts, adjusting the density to the season, species, age, structure, and thickness, achieving a greater and more vigorous growth of the trees. In addition, its products and derivatives have an important substitution effect for non-renewable raw materials, with high energy inputs, a high ecological and carbon footprint, and products from highly polluting fossil fuels, helping the decarbonization process.

In this small territory, 234,000 tons of CO₂ equivalent are currently accumulated with an annual growth of 9,350 tons of CO₂, not counting soil organic matter. They maintain a livestock population of about 300 livestock units for six months and have become very diverse and rich in mushrooms, with the genus Boletus and Lactarius, among others, being highly appreciated as edible species. It is part of the SG-50.005 mycological reserve and is a hunting reserve with species such as the Iberian ibex, roe deer, and wild boar. A fishing reserve is also established.

Considering biological diversity, the upper Pirón basin harbors habitats and species of community interest, boasts more than 600 plant species, and iconic animal species such as the Spanish imperial eagle (Aquila adalberti), the golden eagle (Aquila chrysaetos), the Eurasian black vulture (Aegypius monachus), and the Iberian wolf (Canis lupus signatus). These forest systems are multifunctional, as we have seen previously, and provide important ecosystem services: hydrological regulation, carbon sequestration, obtaining renewable natural products, landscape, culture, leisure, recreation, and hosting plant and animal biodiversity. And they continue to provide them, which has been accredited by their inclusion in the Sierra Norte de Guadarrama Natural Park and the Sierra de Guadarrama National Park.

 

Old images from the State Forest Heritage, deposited in the Segovia Provincial Historical Archive and in the Segovia territorial archive of the Junta de Castilla y León.

The following people collaborated in the realization of this article:

• Francisco Javier Plaza Martín. Forestry Engineer of the Territorial Environmental Service. Segovia. Junta de Castilla y León.
• Mario Lozano Enguita. Forestry Engineer of the Territorial Environmental Service. Segovia. Junta de Castilla y León.
• Celso J. Coco Megía. Forestry Engineer in the Red Estatal de Montes Públicos (State Network of Public Forests), REMP.

 

(versión en español)

Forest Restoration in the Riaza Region. Ayllón and Somosierra Mountains. Segovia.

The Riaza forest region encompasses a tremendously rich historical and cultural heritage, integrated into a vast territory with very diverse ecosystems. It is made up of municipalities, and other local entities, enormously depopulated, but with enormous natural and sociocultural wealth.

A multitude of events throughout history have shaped the territory to this day, with the society of the region adapting to the different needs of each era. This has led to very contrasting situations that, in many cases, left their mark on this cultural landscape.

Different deforestation processes have been happening throughout history depending on the needs of its inhabitants. Already with the pre-Roman natives, the Roman era and, above all, from the Christian period, the activity of livestock entails the progressive disappearance of the high mountain pine forest. The oak groves or Pyrenean oak groves, the holm oak groves, savin groves, pine forests, beech forests and ash groves give way to agriculture and livestock. These forest masses, together with thickets of rockrose, heather or broom, were also used as a source of heat energy, for cooking or to make numerous utensils. In the mid-19th century, as a result of the civil disentailment, the peak of deforestation in the contemporary era is reached.

 

 

Panoramic view of the foothills in the vicinity of the hermitage of San Benito. 2024

In this stage of history, an important movement arises to reverse this declining forest trend. The catalog of lands excepted from sale to private hands in the disentailment is created, and which belonged to the towns, precursor of the Catalog of Public Utility Lands (CUP). This catalog was the first and most important instrument for the protection of forest areas in our country.

With this, a process of forest restoration begins, a paradigm shift based on the concept of "conservar aprovechando -conserving by taking advantage-", that is, taking care of our forests through the sustainable use of their natural resources. In the first half of the 20th century, a process of forest repopulation also began.

 

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In the previous photo, the substantial change in the landscape over the last decades can be observed. The image is taken from the municipal district of Santo Tomé del Puerto, in the direction towards Cerezo de Arriba and Riaza. In the background, large masses of Pyrenean oak groves can be seen, which are included in different mountains of the Catalog belonging to Riaza, the Community of City and Land of Sepúlveda or Santo Tomé del Puerto. To the right are the repopulations with the native Scots pine of mountains listed as La Juncadera and El Raso.

The restoration process was maintained until today under the principle of taking advantage of our mountains from conservation.

Today, when the concept of sustainability has already been assumed, it is more important than ever to continue with this management, making the mountains multifunctional.

During the second half of the 19th century, the consolidation of property began, flying forest nurseries, pastures, infrastructures in the mountains and a myriad of activities that shape our current landscape are created. These traditional activities, which have maintained this cultural landscape, persist today to a greater or lesser extent. Through them, renewable natural resources such as wood, firewood or biomass are obtained; high quality meat from extensive livestock and hunting; honey from beekeeping, mushrooms, etc. This multifunctionality is reinforced when ecosystem services demanded by society are added to the equation, such as regulation of the hydrological cycle, control of erosive processes, CO2 capture, conservation of biological and geological diversity or support for numerous sports, leisure and cultural activities related to nature. These mountains have sustainable forest management certification by the PEFC and FSC systems, and are externally audited to the Administration.

 

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In this composition, the evolution of the landscape in recent decades can be observed with views towards the nuclei of Sigueruelo, Casla and Prádena, from the Puerto de Somosierra. Apart from the reforestation on the slopes of the Sierra mountain, the result of the abandonment of the traditional agrarian system in the evolution of the foothills can be observed. In the old photo, dehesas of oak or Pyrenean oak are observed, along with other species; and juniper or savin groves (Juniperus thurifera) in the mountains of the Sigueruelo, Siguero, Casla and Prádena Catalog, mixed with numerous crops. In the current image, it is observed how rural abandonment causes the old mountain agriculture farmlands (cereals such as rye and wheat, orchards, potatoes, flax fields, etc.) to be completely covered with natural vegetation.

It is colonized by juniper or savin groves, which are currently young and hyperdense, but also holm oaks, oaks or Pyrenean oaks, pines, ash trees, scrubland and grasslands.

Forest repopulations are focused on the steep slopes of the Sierras de Somosierra and Ayllón. An excellent example of restoration is the mountain "EL RASO" nº 265 of the Catalog, located in the municipal term of Cerezo de Arriba. Mountain of excellent quality from all points of view and that houses a great natural heritage. A "Valle Salvaje -Wild Valley-"...

 

During the last decades, in addition to continuing traditional activities promoting innovation, a multitude of works have been carried out in all forest systems, carrying out regeneration work, adjusting tree densities, establishing a better balance of ages or improving pastures and habitats of interest for various species. With all these works, very important tasks are achieved, among them contributing to the prevention of forest fires by generating mosaic cultural landscapes.

This long process of restoring nature is not without dangers and uncertainties. The problem of large forest fires or adaptation to climate change will require an effort from all parties. The primary sector and its associated value chain, although minor, will be the main management tool, as it has been until now, so that these ecosystems continue to play their multifunctional role. Only in this way will society be able to continue benefiting from its sustainable goods and ecosystem services.

 

 

 Forest repopulations and nursery in the vicinity of the hermitage of San Benito towards the Sierra. 1964-2024

Old images from the State Forest Heritage deposited in the Segovia Provincial Historical Archive and in the Segovia territorial archive of the Junta de Castilla y León.

The following collaborated in the realization of this article: 

• Francisco Javier Plaza Martín. Forest Engineer of the Territorial Environment Service. Segovia. Junta de Castilla y León. 
• Mario Lozano Enguita. Forest Engineer of the Territorial Environment Service. Segovia. Junta de Castilla y León.
• Celso J. Coco Megía. Forest Engineer at Cesefor. REMP.

(versión en español)

A changing landscape supported by forest management.

River Valley and La Granja. 1964-2024. Segovia Provincial Historical Archive/Mario Lozano Enguita

 

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We show a brief summary of the evolution of the territory and the mountains of the wonderful surroundings of this Segovian municipality, where the palace of La Granja de San Ildefonso or Felipe V, the palace of Riofrío or Isabel de Farnesio and the ruins of the palace of Valsaín or Felipe II are located.

 

Palace of Valsaín circa 1633, work of Felix Castillo. Commissioned by Felipe II. There were already previous constructions from the House of Trastámara that they used as a hunting and recreation pavilion. You can see the state of the Segovian mountains of Valsaín at that time.

  

In the 1964 panoramic aerial image that we reproduce, you can see the state of the mountains in the Cambrones River valley, located northeast and in front of the Segovian mountains of Valsaín. Part of the town of La Granja can be seen. Some architectural elements are distinguished, among which some stand out, such as the Royal Glass Factory commissioned by Carlos III, the Polishing House of the Royal Factory, part of the gardens of the palace of La Granja or the current glass factory recently built by then.

 

The Pyrenean oak grove that is observed is the "La Mata de la Saúca" mountain. The slopes of the mountain range, which in their day were Scots pine forests, appear completely cleared of trees, with poor soils as a result of secular use as pastures for sheep, fundamentally. In the left quadrant you can see the forest house of "La Pedrona" and the flying forest nursery, where the plants for reforestation were produced. Currently this nursery has been converted into an arboretum of various species, many of them existing in the gardens of the palace of La Granja. Also noteworthy are "Peñas Buitreras" and the famous "Chorro Grande" and "Chorro Chico". 

Image by Mario Lozano

 

In the previous photo, the grasslands (cervunales) surrounded by broomlands can be seen, which are relegated to the higher parts, high plateaus of the territory. These cervunales have not varied in extension and composition since the reference photo. In the image we distinguish alternations of glandular orthogneisses with leucogneisses, which are what form the rocks with scree such as "Peñas Buitreras" and which is observed in the upper right part. On the previously deforested slopes, the Scots pine repopulations carried out manually with soil preparation are observed, either by yoke of oxen or by manual digging, and whose execution lasted many years. Practically the entire surface has been traversed in first or second thinnings to grade the thickness depending on the season, the species, the age and the structure, diversifying and reducing the combustibility of these forest systems.

Decreasing in altitude we find the Pyrenean oak groves of "La Mata de la Saúca" that have persisted due to their secular use and value for obtaining firewood, and that have evolved favorably during the last decades. In the upper left part, pastures for cattle are maintained, dominated by poor soils, with hardly any organic horizon, and some scrubland areas that have as a dominant species the Adenocarpus hispanicus.

On the ridge of "La Atalaya" you can see the natural colonization of Scots pine and the scrubland due to the decrease in livestock and variation in the type of livestock, from sheep to cattle.

 

 

Image by Mario Lozano

Technology and knowledge have evolved enormously in recent decades in all aspects. In this photo we can observe one of the fundamental tasks in forest repopulations, which is soil preparation. In this case, mechanized digging with a spider excavator has been carried out in the restoration of the La Granja forest fire.

Forest repopulations formerly employed a huge number of workers existing in rural areas and whose work served as a complement in times when agricultural and livestock activity was scarce in the extinct traditional Spanish agrarian system, which completely disappeared in the early eighties. In the following photo we want to pay tribute to all those anonymous people who participated. One of the last cattle drivers who participated in these forest repopulations that currently form part of the public utility mountains nº 257 "Umbría de los Saltillos" and nº 258 "Los Saltillos" and the Sierra Norte de Guadarrama Natural Park and Sierra de Guadarrama National Park in Segovia."

Image by J. Plaza

 

All the material presented here has been thanks to: Fco. Javier Plaza Martín and Mario Lozano Enguita (@birds_grylls). Segovia Territorial Environment Service. JCYL. 

1964 image from the State Forest Heritage deposited in the Segovia Provincial Historical Archive and in the Segovia territorial archive of the Junta de Castilla y León.

 

(versión en español)

Sierra de Guadarrama. Segovia (english version)

This article shows a series of images and videos of different locations in the Sierra de Guadarrama; starting with the following photographic superposition that shows what this territory was like in 1964 and what it is like now.

 

The image showcases a portion of the forest repopulations in the Sierra de Guadarrama, with the repopulations of practically all of Somosierra extending into the background. Above them rise the Fuente del Mojón el Porrinoso and the Pico del Nevero, one of the most remarkable places in the Guadarrama and a culminating territory of the Central System in the form of a relatively extensive high plateau.

 

You can see the previous montage in full screen here.

In addition to the pine reforestation, you can see Quercus petraea oaks in the ravine of the río Viejo, protected from the traditional and repeated pastoral fires for centuries.

 

Some poor soils with acute erosive problems and totally unprotected as seen in the 1964 photo.

In the photo, two mountains can be seen. In the immediate foreground (first slope) "El Hoyo" which is the Public Utility Mountain (MUP) 259 in Sotosalbos. The rest is 285 "Zarzoso, Pedriza and others" in Collado Hermoso (where the Río Viejo is born) located in Segovia.

A bit of history

The population used the scrubland for heating and making charcoal. The firewood of oak or pine was a luxury and very scarce. These pastures were used by locals with sheep and goats. The transhumants came from the Sierra de Neila (Burgos), in Sª de la Demanda and Urbión to the south through the extensive network of cattle trails of Segovia.

The surface of Pyrenean oak groves were very degraded because they were used in coppice for obtaining firewood since it was the only source of energy. The other way was their dehesa through pollarding. In the nearby forest of "El Fraile" and forest "Pirón" their firewood was used almost exclusively for the royal glass factory of La Granja, which was the foundation of Carlos III to acquire those mountains of the Community of Ciudad y Tierra de Segovia. Currently they have improved as conversion thinning is carried out to facilitate their development.

The Scots pine forests were dominant on these slopes: there were two fundamental deforestation processes. One during the occupation by the Celtiberian peoples and the Roman domination. The second and largest, during the Reconquest and from the Christian period, and obviously by the empire of the Merino and Castilian sheep. The entire side of the mountain range is crossed by the Cañada Real Soriana Occidental and many cattle trails, shearing sheds and laundries. Segovia lived on the textile industry associated with wool, becoming one of the most important centers in Spain.

Pine forests where thinning has been carried out; and Pyrenean oak (Quercus pyrenaica) in coppice.

Silviculture

The reforestation took a long time and has all kinds of soil preparations. The highest and last ones were made with terraces (very degraded and sloping soil).

 

 

Largest Quercus petraea population in the Central System. Collado Hermoso, Sª de Guadarrama. Segovia.

 

After the silvicultural treatments carried out, grading densities according to thickness, it is becoming good mushroom forests (Boletus sp.) among other mushrooms.

The adequacy of the thickness in pine and Pyrenean oak forests favors the development and growth of trees and the diversity of species. Its floristic richness is high, around 600 taxa, and there are numerous singularities. The repopulations are used by the black vulture among other raptors and avifauna.

 

 

All the material presented here has been thanks to: Fco. Javier Plaza Martín and Mario Lozano Enguita (@birds_grylls). Segovia Territorial Environment Service. JCYL. 

1964 image from the State Forest Heritage deposited in the Segovia Provincial Historical Archive and in the Segovia territorial archive of the Junta de Castilla y León.

(versión en español)