Unraveling the Differences in Landcover Patterns in High Mountains and Low Mountain Environments within the Valdivian Temperate Rainforest Biome in Chile

Abstract

The Valdivian temperate rainforest (VTR) is a biome on the South American continent with high endemism that has experienced an intensive land-cover change in recent decades due to the expansion of agriculture, plantations of introduced forests, and urban growth. Today, the biome hosts key parts of the country’s agricultural and forestry industries. Previous studies focused on quantifying native forest and plantation cover area and exotic forest plantation area, among others. However, the importance of mountain areas as refuge of native forest in Chile remains unexplored. The aim of this research is to highlight the role of latitude and slope on land cover in the VTR. A new methodological approach was used combining global classified datasets. Our results indicate that high mountain areas are the core location of the remaining primary forests and endemism whereas low mountain areas are dominated by exotic forest plantations. Between 40–48° S (The Los Ríos, Los Lagos, and Aysén Regions and high-mountain areas), in general, serve as a natural reservoir where human-induced land-cover change has not occurred on a large scale. Most public and private conservation areas are in high mountain areas, whereas low mountain areas and plain areas lack conservation schemes and are more prone to land cover change towards forestry. Considering geomorphological features in land cover change analysis can reveal interesting new perspectives in this research area.

1. Introduction

The Valdivian temperate rainforest (VTR) is one of the world’s 36 biodiversity hotspots. These are defined as having at least 1500 endemic plant species and having lost 70% or more of their original habitat extent [1]. This ecosystem is a temperate biome, located in Chile and western Argentina between 33° S and 48° S, which includes different types of forests, shrublands, wetlands, rivers, and lakes. Its general biogeographical features are its location on the South American continent, its Neotropic affinities, and the legacy of the Gondwana supercontinent. Its isolation from other forest biomes has given it its strong endemism [2].

An ecoregion is a relatively large unit of land containing a distinct assemblage of natural communities and species, with boundaries that approximately correspond to the original extent of the communities before major land-use changes occurred [3].

Since European colonization and increasingly during the twentieth century, the area has been stressed by anthropic land-use change processes, including forest plantations, civil infrastructure, urban growth, and the expansion of agricultural land [4,5]. In particular, forest plantations of introduced species have increased the occurrence of wildfires [6]. These processes, with the resulting reduction of valuable biome cover, have caused concern on different levels.

Lara et al. [5] has calculated that native forest cover in the Valdivian rainforest ecosystem in the area delimited in the north by the Maule Region and in the south by the Los Lagos Region shrank from 11.3 million ha in ca. 1550 (the Spanish conquest) to 5.7 million ha in 2007. This is the result of conversion to pastureland, shrublands, and agricultural land. Beginning in the 1930s, plantations of exotic species—eucalyptus and pine—became an important factor in the alteration of uneconomical agricultural or pastureland, especially in the Ñuble and Bío-Bío Regions. The natural and social landscape was transformed for use by the forestry industry, which was seen as an alternative economic strategy in the face of vanishing nitrate mining in the north of the country [7,8]. Several studies, at regional and local levels, have investigated land-use change, climate change, and hydrographic conditions in the VTR, focusing on different aspects. Echeverría et al. [4] demonstrated that recent fragmentation by logging and clearance is associated with dramatic changes in the biome’s structure. [9] investigated the impact of anthropogenic land-use change on populations of the endangered Patagonian cypress (Fitzroya cupressoides) in southern Chile, finding a 46% reduction in its potential habitat between 1999 and 2011. Barrientos et al., 2018 investigated the effects of topography and managed forests on catchment water storage capacity of river catchments within the VTR, showing that climatic changes are more important than landcover changes for runoff behavior within catchments areas in South-Central Chile [10].

In 2021, the Ministry of Agriculture and the Corporación Nacional Forestal (CONAF), Chile’s forest service, published an updated national vegetation inventory [11]. It found that 23.8%, or 18.03 million hectares (MH), of the national territory, has forest cover. Primary or native forest accounts for 19.46% (14.73 MH), while mixed forest (179,125 ha) and forest plantations (3.11 MH) together account for the other 4.34%. In other words, the area of primary forest in Chile is still 5.4 times greater than that of managed secondary forest. However, the former is very unevenly distributed and found mostly in the remote Aysén and Magallanes Regions. However, basic problematic aspects of the national land cover monitoring system are methodological inconsistencies over time and no error estimation, which make comparisons with this dataset unreliable [12].

Urban growth, a decreasing or stagnating rural population, new economic dynamics, improving conservation efforts, and new observation methods justify an update of land cover in the Chilean part of the Valdivian temperate rainforest [13,14,15]. In addition, this study considers high-mountain areas within the region that are the natural refuge of endemic primary forest formations. Moreover, although land cover analysis on a large scale has been facilitated by the availability of good quality data on a global scale [16], there is as yet no analysis that quantifies and interprets actual land cover with good quality data on a biome scale.

Since other studies examined only the local or regional level in the VTR biome, we fill the gap examining land cover on the whole biome area within Chile. Effects of terrain on land cover characteristics, differentiating between high and low mountains will be highlighted.

Based on these assumptions, we formulate the following research questions: What are the distinct land-cover patterns in the biome? Can we determine distribution patterns of primary forest and secondary forest? How important are low and high mountain areas on land cover patterns in the Chilean part of the Valdivian temperate rainforest biome?

2. Materials and Methods

2.1. The Valdivian Temperate Forest: Boundaries, Climatic Characteristics and Recent History

Recent proposals on the biome’s limits fall into two types. The stricter type includes only laurel forests while the other broader definition also includes Andino-Patagonian forests and temperate deciduous forests [17,18,19,20]. In our study, we apply the broader type. Using the Olson et al. [3] delimitation, the VTR biome occupies a size of around 250,000 km² between latititudes 32° S and 47° S and longitudes 75° W and 69° W, 80% being in Chilean and 20% on Argentinian territories.

To the north, the ecoregion is bounded by the Chilean Matorral ecoregion, dominated by sclerophyllous Mediterranean forest, woodlands, and scrub. This ecoregion, defined by trees adapted to dryer conditions, reaches in the Central valley a southward extension to 37° S, separating the VTR biome into two parts. However, isolated patches of Valdivian temperate forest occur in northern Chile as remnant glacial refuges. This is the case, for example, for the Fray Jorge National Park in the Coquimbo Region. To the south, the biome merges into the Magellanic subpolar forest, between 47–48° S [2,21].

The Atacama Desert and the Argentine pampa separate the Magellanic subpolar and Valdivian temperate rainforest ecoregions from other South American forest biomes [22], a situation that has persisted from the Quaternary through to the present. This has resulted in strong endemism. Half of the plant genera and a third of the woody plant genera are native [23] while 60% of the amphibians and reptiles, 20% of the freshwater fish and mammals, and 30% of the birds are endemic to southern temperate rainforests [24]. With plant affinities from Gondwana over 200 million years ago (for example, Araucaria araucana) and some of the largest and oldest conifers in the world (for example, Alerce Fitzroya), the Valdivian rainforest ecosystem is a unique area of the world [2] (Figure 1).

Several climatic characteristics of the VTR can be determined for the reference years 1991–2020 using the ERA5 dataset [25]. The annual precipitation increases from 359 mm at Valparaiso in the north to 5529 mm at Golfo de Penas in the south and from lowland to mountain areas. The average annual precipitation for the whole biome is 2192 mm (Figure 1b).

Temperature decreases gradually from north to south and with increasing altitude. The minimum annual average of 2.2 °C value can be found in the mountainous area in the east of Santiago. The hottest average annual temperature can also be found in the Santiago Region with 15.2 °C, close to the area with the lowest average precipitation (Figure 1c). Increasing summer droughts and heatwaves is stressing the native vegetation especially in the northern dryer and hotter areas, for example in the case of the Nothofagus obliqua tree [26,27]. The Chilean Mattoral sclerophyllous formations are better adapted to these hotter and dryer conditions.

2.2. History and Productive Transformation within the Biome

Before migration and rural appropriation by Chileans and European immigrants changed the area’s character in the late nineteenth century, the Chilean part of the Valdivian rainforest was sparsely populated, with few urban areas. The rural economy focused mainly on exploitation of the forest and agricultural production [8,29]. Beginning in 1940, forest plantations were established to protect eroded soils and to support the development of the forestry industry. However, the state also created a series of national parks. In 1926, the Vicente Pérez Rosales National Park was established in the mountain range of Osorno and Llanquihue [30]. Later, the Malalcahuello Forest Reserve (1931) and the Tolhuaca (1935), Nahuelbuta (1939), Villarrica (1940), Puyehue (1941) and Conguillío (1950) National Parks were created. In the 1960s, they were followed by the Nalcas and China Muerta Forest Reserves and the Huerquehue National Park in the Araucanía Region [31].

During the Agrarian Reform, implemented in 1962–1973, large areas of forest were nationalized, forming huge state-owned properties. The best-known case is the Panguipulli Forestry and Timber Complex (COFOMAP), which brought together various properties in the Valdivian Mountain range and covered more than 360,000 ha [32]. The military dictatorship put an end to the Agrarian Reform, returning expropriated land, forming private properties, and auctioning off numerous forest lands. This is the origin of much of the enormous concentration of land in the hands of forestry companies in southern Chile, both in low-mountain and plain areas that were converted from agricultural to forestry use [8,29,33]. A subsidy for forest plantations, established in 1974, was a further factor in their proliferation. In addition, the dictatorship privatized a large part of the state’s forestry interests (pulp and wood processing plants). The resulting modernized industrial forestry activity represents the main threat to Chile’s Valdivian rainforest primary forest formations. Research shows that the industry has increased poverty and inequality in nearby indigenous and non-indigenous communities and violent conflict about land usage [34,35].

Since the mid-1980s, land in southern Chile has also been used to cultivate berries and flower bulbs for export and they have been followed by other fruits such as apples, cherries, and European hazelnuts [33]. New uses of rural spaces emerged. After the crisis of peasant and traditional agriculture in the 1980s, forestry and livestock farming for export began, along with an increase in rural activities linked to the development of energy projects (hydroelectricity, bioenergy and wind power) and tourism (of different levels, from hotels to rural community tourism), as well as real estate development, an increase in the subdivision of land for second homes and even real urbanization of areas near mountain towns and lakes [36]. Anomalous urbanization rates and rural subdivisions in formerly rural areas were observed in the vicinity of the tourist towns of Pucón and Villarica [37]. On the contrary, in recent decades, new conservation initiatives, implemented by both the state and private actors, have also meant the creation of additional parks and reserves [38,39,40]. Most recently, vast areas of this biome have become part of the public conservation scheme: for example, the Corcovado National Park created in 2005, the Melimoyu National Park and the formerly private Pumalín Park were incorporated into the National System of State-Protected Natural Areas (SNASPE) in 2018.

2.3. Methodology

Extensive bibliographic research was carried out using known internet research engines (for example, Google Scholar, SCOPUS). We looked for publications in Spanish, English, French, and German with the following keywords (Valdivian rainforest, ecoregions, conservation, land-use change, and land-use dynamics). Geostatistical data were acquired from different sources. For the continental overview, we used the Terrestrial Ecoregions of the World (TEOW) published by the WWF [3]. In the case of Chile and for the sake of precise calculation, we acquired geodata on administrative boundaries as well as using openly accessible national geodatabases. In Chile, the boundaries of the country’s administrative regions are available from the Undersecretariat of Regional and Administrative Development (SUBDERE) [41]. Updated geolocated information about public protected areas in Chile was obtained from the National System of Wildlife Areas SNASPE [42].

To process these datasets, QGIS 3.20.3 was used. The data for the land cover map was acquired from the Copernicus Global Land Service map provided by the European Union. With the PROBA-V Sensor, there is open access to yearly land uses on a global resolution of 100 m between 2015 and 2019 [16,43]. Validation tests of the datasets have confirmed an accuracy of 80% on a global scale [43]. The most recent dataset of 2019 was used. To differentiate between primary forest without any signs of human activity and managed forest, we used the global planted tree extent 2015 database [44] and reclassified the relevant areas into a new class. These areas may include natural regenerating forests with signs of human activities: for example, logging, clear cuts, etc.; planted forests; short-rotation plantation for timber; oil palm plantations; or agroforestry. The managed forest dataset is derived from the Copernicus Globals Land Service, with it being from the same source as the other classifications used in this work. Thereby, a compilation of the two datasets is valid and consistent. Accuracy was reached between 58% and 80% on a global scale, which was sufficient for our intended overview analysis.

To answer the question about the relevance of mountain areas for the preservation of the biome’s primary forests and forestry expansion, we used a global mountain classification dataset suggested by Sayre et al. with a 250 m resolution elevation model dataset from 2010 [45]. We differentiated between high mountain and low mountain areas because both play significant but very different geomorphological roles in the biome and landcover characteristics.

High mountain sites were defined as having between 51% and 100% of their raster cells with adjacent slopes of ≥ 8% and differences in elevation > 900 m within a 3 km neighbourhood window analysis (NAW). Relief thresholds were applied to exclude tablelands from high mountain areas. In contrast, low mountains have the same slope parameter values but relative relief in the NAW analysis is limited to 301–900 m [45,46]. We summarized high mountains and scattered high mountains and low mountains and scattered low mountains into corresponding classes. This mountain definition is appropriate for our analysis of as it allows us differentiating on two geomorphological relevant landform classes and having a high resolution. It does not consider absolute altitude in its definition, and it also allows for comparative analysis as it can be applied on global level. The other argument using this global database is that there does not exist a legally recognized definition of mountain areas in Chile.

To illustrate our results on recent land cover, we focused on the areas where the biome of interest overlapped with one of the country’s regions (the administrative division immediately below the national level). Types of land cover important for anthropic intervention were highlighted. These include the following classes: primary forest, all types of managed forests, herbaceous vegetation, cultivated areas, shrubland, and built-up areas. To compare high-mountain areas with other areas including low mountains and other non-mountainous terrestrial landforms, we carried out three calculations. The overview calculations considered the whole overlapping area of the Valdivian temperate rainforest biome and Chile’s administrative regions. The other calculations involved only the high-mountain and low-mountain areas within the investigated overlapping area, excluding all others (Figure 2).

This GIS approach allowed us to identify focus regions where certain land uses are concentrated (native forest and plantain forests) in mountain areas or non-mountain areas. To validate the GIS methodology with the literature review and fieldwork, we applied the triangulation method suggested by Olsen 2004 [47]. This allowed us to link the qualitative (literature review, field research) and quantitative data (GIS analysis).

3. Results

3.1. Primary Forests Prevail in the South and the Main Andean Range

Mountain areas are highly relevant in most of the Chilean part of the Valdivian temperate rainforest. High mountain areas and low mountain areas comprise 85% of the investigated area, making them the dominant geomorphological factor. In its northern part, from the Valparaíso Region south to the Araucanía Region, the biome is confined to the mountainous areas of the Coastal Range and main Andean Range and does not include the plain areas of the Central Valley. The Chilean Matorral biome extends south to the Araucanía Region. The climatic shadow effect of the Coastal Range helps to explain its extension to 39° S since it prevents wet air currents from the Pacific Ocean reaching the area, creating drier and arid conditions this far south. Therefore, only the Los Ríos and Los Lagos Regions correspond almost exclusively to the Valdivian rainforest biome. The Aysén Region has an ice field that is not included, and the southern part corresponds to the Magellanic subpolar forest biome, giving the Valdivian rainforest biome a share of around 50% of the total area of the region (Figure 3,

Table 1. Size and share of Valdivian temperate rainforest biome and mountain and areas in overlapping zones in Chilean regions in km² Source: Own calculations out of databases mentioned in methodology part.

Region of Chile	Total Area of the Region	Overlapping Area	Share of Biome (%)	High-Mountain Areas	Share of High Mountains (%)	Low-Mountain Areas	Share of Low Mountains (%)	Plain Areas	Share of Areas (%)
Valparaíso	16,237	1338	8.2	1244	93.1	79	5.9	15	1.0
Santiago	15,395	6067	39.4	5850	96.4	135	2.2	82	1.3
O’Higgins	16,347	5917	36.2	4422	74.7	1105	18.7	390	6.6
Maule	30,307	20,515	67.7	12,521	61.1	6956	33.9	1038	5.0
Ñuble	13,091	7215	55.1	3968	55.1	2915	40.4	332	4.5
Bío-Bío	23,985	17,846	74.4	7604	42.7	7708	43.2	2534	14.1
Araucanía	31,797	21,487	67.6	10,793	50.3	8366	38.9	2327	10.8
Los Ríos	18,217	18,209	100.0	7316	40.2	7096	39.0	3797	20.8
Los Lagos	48,319	47,937	99.2	23,879	50.1	8057	16.8	16,001	33.1
Aysén	106,497	53,473	50.2	36,416	68.0	14,549	27.2	2509	4.8
Total Chile	765,102	200,003	26.1	114,018	57.0	56,965	28.5	29,020	15

).

Our calculations applying the datasets (Figure 2) show that the northern part of the biome from Valparaíso to the Araucanía Region is almost completely dominated by mountainous areas. Low mountains predominate in the Coastal Range and high mountains in the main Andean Range. This is due to the differences in the relative relief of these two mountain ranges. In the Coastal Range, high mountain forms are found only in the Nahuelbuta Range between the Bío-Bío and Araucanía Regions and in some isolated parts of the Los Ríos, Los Lagos, and Aysén Regions. Very high shares of high mountains are seen in the Valparaíso and Santiago Regions (93% and 96%, respectively). Low mountain areas are particularly relevant in the Maule (33.9%), Ñuble (40.4%), Bío-Bío (43.2%), Araucanía (38.9%), and Los Ríos (39.0%) Regions. Plain areas of relevant size exist only in the south of the Los Ríos Region and, to a greater extent, in the Los Lagos Region. Plain areas also exist on the eastern side of Chiloé Island.

3.2. More Primary Forest Than Expected—Arid Plant Cover in the North

Our calculated results show that primary forest accounts for 44.1% of the Chilean part of the Valdivian temperate rainforest biome which makes it the largest land cover class. This forest is distributed very unevenly within the biome, gradually increasing towards the south. In the most isolated Aysén Region in the far south, 69% of land cover can still be considered primary forest.

The land cover distribution map and table (Figure 4,

Table 2. Land use distribution in the biome studied considering the whole overlapping area and focusing on high and low mountain areas in relative shares (in percentage) Source: Own calculations.

Regions of Chile	Total Area	Primary Forest	Forestry	Herbaceous	Cropland	Shrubs	Built Up	Other Types
Valparaíso		10.7	13.5	4	6.3	63.8	0.7	1
Metropolitana de Santiago		3	2.5	25.1	5.6	27.8	4.4	31.7
O’Higgins		15.3	23	18	6.1	14.7	0.4	22.5
Maule		16.7	31.2	12.9	5.2	6.3	0.1	27.7
Ñuble		24.7	42.5	13	5.9	4.5	0.1	9.2
Bío-Bío		23.5	55.2	7.6	3.3	2.4	0.9	7.1
La Araucanía		32.8	45.3	6.6	5.1	3.2	0.2	6.8
Los Ríos		34.9	46.3	2.1	8.5	0.1	0.2	7.9
Los Lagos		52	24.2	4.7	5.2	0.2	0.2	13.4
Aysén		69.3	1.2	10.8	0.8	2.6	0	15.3
Chile total		44.1	25	8.6	4.1	3.6	0.3	14.1
Regions of Chile	High Mountains	Primary Forest	Forestry	Herbaceous	Cropland	Shrubs	Built Up	Other Types
Valparaíso		10.6	12.8	4	5.7	65.3	0.5	1.1
Metropolitana de Santiago		3.1	2.1	26	4.8	27.5	3.7	32.7
O’Higgins		19.7	5.9	23.4	4.2	17	0.4	29.4
Maule		24.7	5.2	19.9	1.5	5.2	0	43.4
Ñuble		40.6	11.4	23.2	3	6	0	15.8
Bío-Bío		48.2	17.7	15.9	2.8	4.5	0	10.8
La Araucanía		57	16.8	10.7	2.8	4.1	0.1	8.5
Los Ríos		66.8	21.5	4.1	0.6	0.1	0	6.9
Los Lagos		68.7	7	7.6	0.2	0.2	0	16.3
Aysén		68.7	1.2	10.9	0.8	2.3	0	16.1
Chile total		55.4	7.3	12.5	1.5	4.8	0.2	18.4
Regions of Chile	Low Mountains	Primary Forest	Forestry	Herbaceous	Cropland	Shrubs	Built Up	Other Types
Valparaíso		14.97	20.2	5.4	7.2	48.7	3.5	0
Metropolitana de Santiago		0.81	8.6	2	17.3	50.6	16.4	4.2
O’Higgins		2.14	77.2	2.19	9.2	7.9	0.6	0.9
Maule		3.95	75.4	1.78	9.6	8	0.3	1
Ñuble		5.57	81.7	0.45	9.3	2.3	0.2	0.4
Bío-Bío		5.27	85.9	1.66	3.2	0.8	1.2	1.9
La Araucanía		9.66	77.5	2.72	6.2	2.8	0.3	0.8
Los Ríos		15.69	75.3	0.63	7.7	0	0.2	0.5
Los Lagos		51.71	43.1	1.2	1.7	0.1	0.1	2.1
Aysén		77.28	1.1	9.96	0.9	3.5	0	7.2
Chile total		33.6	51.9	3.9	4.5	2.8	0.3	2.9

) show that the northern part of the biome—the Valparaíso, Santiago, and O’Higgins Regions—has some obvious characteristics of arid vegetation with shrubs and grassland formations dominating the flora. On steep slopes and at high altitudes, no comprehensive vegetation cover can be observed, due principally to aridity and the high-mountain climatic conditions. These areas area already located in the Chilean Matorral biome.

A refinement of the ecoregions’ delimitation suggested by [3] seems appropriate. In the Maule Region and further north in the main Andean Range, there is a very arid area with sparse vegetation or none that can be considered to correspond to the Southern Andean steppe climate or high-mountain climate. Further south, beginning in the O’Higgins Region, primary forest formations and secondary forests dominate the biome. Continuing south, three general observations can be made. In the main Andean Range, primary forest formations dominate while, in the Coastal Range, secondary forest or plantations dominate. In the few plain areas in the south of the Los Ríos Region and in the Los Lagos Region, the cover alternates between secondary forest and cropland. This is the only area where cropland plays a significant spatial role.

Primary forests still account for over 30% of land cover in four regions: Araucanía (32.8%), Los Ríos (34.9%), Los Lagos (52.0%), and Aysén (69.3%). The total investigated area of the Chilean part of the Valdivian temperate rainforest contains 44.1% primary forest, making this the dominant land cover ahead of forestry (25%). The Valdivian temperate rainforest comprises different dominant formations (laurel, Andino-Patagonian and temperate deciduous southern beech forests) and, to a lesser extent, Fitzroya forests. Our results aggregated all these formations.

3.3. Low Mountains Areas: Exotic Forest Plantations Paradise

We determined distinctive regions where secondary forests and plantations dominate. From north to south, this is the case of the following regions: Ñuble (42.5%), Bío-Bío (55.2%), Araucanía (45.3%), and Los Ríos (46.3%). Further south, the share of this type of land cover falls as compared to primary forest and, in the Aysén Region, drops to just 1.2%.

Our analysis shows that slope is very important for land cover characteristics and patterns. The dominant land cover in low mountains in the Valdivian temperate rainforest biome corresponds to plantations or secondary forest, with a share of 51.9% (Table 2). In several regions, such as O’Higgins (72.2%), Maule (75.4%), Ñuble (81.7%), Bío-Bío (85.9%), Araucanía (77.5%) and Los Ríos (75.3%), secondary forest reaches very high proportions of landcover, mainly at the cost of primary forest. Most of the Coastal Range corresponds to low mountain formations. With this high share, low-mountain areas are prone to other more negative effects of forestry activity. They include a higher probability of wildfires, especially in areas with dense forest plantations of flammable pine and eucalyptus species; the loss of ecosystem services due to a reduction in biodiversity; and limited access for nearby communities since most plantations are privately owned and entry is restricted or costly. Particularly dangerous are poorly managed or unmanaged plantations near settlements without a security buffer, which occur frequently in Chile. More resilient landscapes can only be achieved through institutional regulations [48]. In recent decades, the Chilean forestry industry has been criticized on grounds that include the introduction of faster-growing exotic species and its expansion into many areas of formerly primary native forest, resulting in heavy ecological damage. Particularly on social and environmental matters, the industry lacks sustainable development [49,50]. In the case of the municipality of Panguipulli, located in the Los Rios region, new conservation policies such as Payments of Ecosystem Services (PES) and REDD+ increase the already strong inequalities of land ownership existing in the area, as large landowners have better bargaining possibilities and can guarantee ecosystem services at lower costs [51]. On the other hand, in the northern area, which is prone to more frequent drought events—for example, the megadrought between 2010 and 2015—forest plantations are the only land cover class, which has an observable greening effect in the enhanced vegetation index (EVI). Plantations also have a positive effect on biomass production in areas where climatic conditions are too tough for native forests to thrive [27].

On Chiloé Island and in the remote Guaitecas archipelago south of 42° S, there are still large extensions of primary forest in low-mountain and even plain areas. Their remoteness from human economic centers and increasing legal protection can explain this phenomenon.

3.4. High Mountains as a Natural Refuge of Native Forests

By contrast, high mountains represent a refuge for primary forest formations. As a result, the steeper main Andean Range is the natural refuge of primary forests, except for dry areas in the north and high areas in the south, where snow cover and low temperatures limit the forest. This observation focuses on areas in the high mountains of the Ñuble (40.6%), Bío-Bío (48.2%), Araucanía (57.0%), Los Ríos (66.8%), Los Lagos (68.7%) and Aysén (68.3%) Regions. This is partly because of the relative inaccessibility and isolation of high mountains in the south of Chile. Population centers and the dominant economic activities are located almost exclusively in valleys or plain areas. Low mountains permit the installation of the infrastructure required for industrialized forestry activities (storage areas; roads) and the use of heavy machinery. Conversely, high mountains areas, with their slopes, isolation, and high legal protection, hinder these activities. Our calculations from the above-mentioned geodata sets show that in total there are 42,000 km² of public protected areas in the Chilean VTR. Of this area, 28,628 km² are in high mountain areas or, relatively speaking, 68%. In the Coastal Range, with its mostly low mountains, the remnants of primary forest are in a few high mountain areas or their vicinity. Examples include the Nahuelbuta Range in the south of the Bío Bío region and the Alerce Costero National Park and the coastal forests of the Los Rios Region [31].

Considering native forests as core of biodiversity hotspots, anthropic land use changes in plain and low mountain areas within the VTR resulted in the high mountains becoming the refuge of endemic biodiversity. These findings confirm that the high mountain VTR plays a key role in biodiversity conservation in Chile.

4. Discussion

We investigated the land-cover patterns in the Valdivian Temperate Rainforest VTR biome, focusing on the distribution patterns of primary and secondary forest. In this process we also examined the relevance of low and high mountain areas and their relevance on land-cover patterns in the Chilean part of the VRT. With our approach we were able the answer all the research questions we had formulated.

What are the distinct land-cover patterns in the biome? Can we determine distribution patterns of primary forest and secondary forest?

The primary forest clearly increases from north to south and maintains a high presence in the southernmost Los Lagos (52.0%) and Aysén (69.3%) regions. Climatic limiting factors in the north that consist of dryer and hotter Mediterranean and even semi-desertic conditions are one reason. Especially in the three northernmost regions (the Valparaíso, Santiago, and O’Higgins regions) severe arid or high-mountain influences have shifted vegetation cover towards shrubs or no cover at all (Figure 1). These dry conditions caused by the shadow effect of the surrounding mountains (intraandine dry valley) also explain the expansion into till nearly 40° South of the Chilean Mattoral sclerophyllous biome formations (Figure 3 and Figure 4). Furthermore, human intervention on land cover is substantially larger in the more populated and economically more dynamic northern regions (Figure 4, Table 2).

How important are low and high-mountain areas on land cover patterns in the Chilean part of the Valdivian temperate rainforest biome?

Low mountains areas are the core area of the biomes managed forests. From the O’Higgins Region (77.2%) to the Los Ríos Region (75.3%), the relative share of forestry areas reaches over 75% and is highest in the Bío-Bío Region (85.9%), which is the result of the expansion of the forestry industry the last decades in Chile. New datasets including large-scale (national, continental, and global) confirm the importance of forestry in Chile, and differentiation between low and high mountains is highly relevant for explaining human-induced land cover change. Our findings coincides with the results reported by Braun 2022 [52] investigating the process of land cover change in the coastal mountains between the Maule and Bío-Bío region, which are mainly low mountains. In these areas the transition towards managed forests has in nearly all areas been at the cost of primary forests since 1975 (Figure 4, Table 2). This differentiation is important to consider in the context of potential land uses, future conflicts, conservation policies and spatial planning schemes in these areas.

The primary forest clearly increases from north to south and maintains a high presence in the southernmost Los Lagos (52.0%) and Aysén (69.3%) Regions. In all regions with significant primary forest formations, from Ñuble southwards, high mountains represent the natural refuge of primary forests. Climatic aspects like combination of high precipitation rates and temperature variability, in compass to demographic distribution in Chile (highly concentrated between Valparaíso and Concepción cities (32–37° S) and concentrated in the valleys and plains) can explain this pattern and amplify it.

These areas are also those most strongly protected by private and public conservation initiatives [38,39,40,53] (Figure 3). Over 48 out of the 59 areas in the biome that are protected by SNASPE are located at least partly in high mountain areas. From of this observation, it can be concluded that the low mountain areas of the VTR biome are lacking a conversation scheme what is the case within high mountains areas, which only partly can be compensated by private initiatives [53]. Furthermore, urban expansion in geomorphologically risky areas occurs almost exclusively in low mountain areas in southern Chile [54].

This differentiation is also relevant if we consider climate change indicators like heatwaves trends indicated by González-Reyes et al. 2022 [55], which observes an increasing heatwave probability in high mountain Andean areas during the November to March summer months between the period from 1980 till 2020.

Furthermore, high floods and heat exposure risks in the steep high mountain slopes of the metropolis of Santiago exist because denudated land present a high erosion potential; this was investigated on a local scale by Kellenberg et al. [56].

In this case, wisely planted and managed forests formations can help minimize the risks of landslides and heat exposure.

Our research indicates that the demographically and economically dynamic Valdivian rainforest biome is prone to future land-cover changes. Therefore, mitigation measures and wise land use alteration decisions considering social, economic and environmental parameters in the Chilean context will be decisive in determining whether sustainable development will occur. Low mountain areas in this biome should be the focus of future policies regarding the forestry industry. In Chile, the forestry sector has still not achieved sustainable development, although constitutional and socioeconomic evolution has improved the situation in recent years [49,51,57].

In turn, from a methodological perspective, this research shows that with the availability of new datasets, it is possible to evaluate land-cover change with geomorphological features (for example, mountainous areas, slope, exposure). The results demonstrate that analysis of this type can also be applied to other biomes and administrative entities. Comparative analysis with other forest biomes along the Andes or elsewhere in the world seems a promising research field, mainly to understand future changes based on anthropogenic activity and climate change evolution. The methods we applied in our study are adequate from the global to regional level; for higher precision for local studies, additional classification refinements might be suitable depending on the case. A weakness of this research approach that it is not comparing how landcover changed over time (e.g., 10 years), which would clarify in which form and which landcover class is changing in time.

Higher precision local studies may justify additional classification refinements. Applying our methodological approach, comparative analysis with other forest biomes, tropical or temperate, could provide greater understanding of land cover distribution patterns. We showed that land cover change towards industrial forestry is the main driver of primary forest loss, but on the local level, outcomes may differ as socio-economic and environmental conditions vary within this vast forest biome. Comparative analysis with other forest biomes, tropical or temperate, could reveal knowledge of land cover distribution patterns applying our methodological approach. Improving public policies to protect mountain areas in Chile is crucial to generate best conservation results that protect the native forest.

We have shown that low mountain areas, which represent the key area of land cover change towards managed forest ecosystems, should be the focus of future studies addressing this phenomenon. Other environmental evaluations, including landscape biodiversity analysis, drainage behavior and socio-economic impacts and their interactions with slope and other morphological properties could enhance new research.