Keywords

1 Introduction

Temperate forest ecosystems without major human intervention in western Patagonia are a natural treasure and global heritage [7, 79, 115]. Numerous rivers and winding crystalline streams are born in these forests. A closer look reveals that the stream-forest interface is a complex and dynamic zone that is teeming with life. River ecosystems play essential roles in the transport of sediment, rocks, leaves, nutrients and dead wood, demonstrating a close relationship between what happens in the entire watershed, the banks and the watercourse [43, 53]. Considering the importance of water for life, this connection between forest and water is essential for our survival as a society.

Ancient forest ecosystems, scarcely modified by human action, are important due to their capacity to sequester and store carbon [63, 93, 92] and water [36], their role in soil protection and water quality, regulation of hydrological regimes, nutrient cycling and retention [47, 100] and the geomorphology of associated river systems [16, 28, 113]. Due to the global decline in forest area, an increasing number of publications and reports address issues such as the rate of forest cover loss [42, 77], remaining biomass in intact forest landscapes [91], habitat fragmentation levels [29, 30, 41], the human footprint on the landscape [101, 111] and priority areas for conservation and restoration [117]. However, comparable regional-scale studies are generally scarce in Patagonia [90].

As in other regions, major forest losses in western Patagonia are due to human actions such as large fires, timber extraction, cattle ranching, and to a lesser extent, the replacement of forests with plantations of exotic trees and agriculture [15, 40, 77]. These anthropogenic impacts continue to expand, resulting in the decrease of intact forest area [40]. After 100 years of intensive landscape use, Chile’s forest area has suffered significant reductions [6]. It is estimated that most native forests in western Patagonia were still pristine only 100–200 years ago, despite some localized impacts from management by Indigenous people [8, 13, 57]. Despite the losses, Patagonia is home to potentially the largest area worldwide of temperate forests and wetlands without major human intervention and has become a refuge for the biota of these ecosystems [9, 10, 65, 99].

Global-scale forest mapping efforts have advanced in recent years by defining areas of remaining intact forests or landscapes as critical conservation units, and analyzing their size and connectivity [42, 91, 115]. However, the watershed seems to be the most relevant unit for conservation from an ecosystem perspective [45, 61]. Considering the close relationship between forest, water, and fluvial ecosystem in watersheds, it is especially relevant to study the forests of western Patagonia that are intact or with very little human impact, because they represent a global ecological reference condition. The identification and mapping of watersheds with forests displaying very little intervention requires a set of restrictive conditions: a forest ecosystem unaltered by human activity, adjusted to the contour of a watershed whose watershed boundary lines are identifiable up to a downstream drainage point, and without significant human impact along the stream drainage network.

2 Scope and Objectives

The objective of this chapter is to determine the distribution of forest watersheds without any major anthropogenic intervention (Table 1) in the area of western Patagonia stretching from Petrohué River to Tierra del Fuego including Chiloé Island (42–56°S).

Table 1 Some flagship species of freshwater and terrestrial fauna using mapped intact forest and river ecosystems
Full size table

We also highlight the conservation value of these terrestrial and freshwater ecosystems, considering their global importance and as a local conservation unit (see Fig. 1 for diagrams that include some typical ecosystem transitions at the terrestrial-aquatic interface in valleys of mountain and coastal basins of western Patagonia).

Fig. 1
2 illustrative graphs of the zonation of coupled terrestrial-aquatic ecosystems by deciduous and evergreen forests. They have autotrophic stream originating at Alpine zone and slopes down steeply through various zones including autotrophic seasonal and open to land in the river valley.

Conceptual scheme of the altitudinal gradient of terrestrial ecosystem-water interface of the study area in Chilean Patagonia. a Zonation of coupled terrestrial-aquatic ecosystems in the deciduous forest zone. Typical scheme of mountain range river valleys. The streams that originate in the high mountains pass through areas of steeper slopes and stunted forests. In some cases, they pass through primary forests with little intervention before reaching the zone affected by anthropogenic effects (in areas where the slope is less steep, accessed by trails and secondary roads). This zone is usually the altitudinal limit of historical fires (sometimes affecting only the understory). The geomorphological gradients of the valley, as well as anthropogenic impacts, are changes in the physical habitat of the streams and rivers in this zone. b Zonation of coupled terrestrial-aquatic ecosystems in the evergreen forest zone. Shown is a U-shaped valley formed by glaciation, often at low elevations near the coast. The forest and stream usually have little intervention after the change of slope to higher elevations (1200–1100 m), because they are hard to reach. Below this zone, the transition to the impacts of fires from the last century begins (often mild at this altitude, affecting only the understory). These geomorphological gradients in the valley, as well as the anthropogenic impacts, are characteristic changes in the physical habitat of the streams and rivers: (i) waterfall: high slope zone where the water falls almost vertically; (ii) pool and riffle: sequence of rapids and turbulent flow zones with low velocity and deeper pools; (iii) stream: laminar flow zone; (iv) braided: braided channel, network of small channels separated by small, temporary islands, which are produced by the decrease in slope of the channel

Full size image

The results include a map of intact forested watersheds for western Patagonian region (41°42′S, 73°02′W–56°29′S, 68°44°W), followed by an analysis of the distribution of these intact forest watersheds according to land use categories, bioclimatic gradient, forest types and their representation within protected areas (e.g. National System of Protected Wild Areas (in Spanish SNASPE) and private conservation initiatives). Finally, some of the main threats currently facing these forest ecosystem watersheds in the Patagonian region are discussed.

Box 1

What is considered to be an intact/pristine forested watershed in this study?

In this study the intactness or alteration of a forest or watercourse is based on the fact that all environments exhibit varying degrees of human intervention and cannot be treated in absolute values. One view (International Conference: Intact forests of the twenty-first century, University of Oxford, June 2018) that considers landscapes along a gradient of degrees of intervention is:

An illustration has a bi-directional arrow with 2 elements at either end. They are no intervention and totally degraded.

The concept of intact forested watershed in our study is the watersheds that are closest to presenting a state of no intervention by human beings. In order to arrive at a definition of systems that are “intact” or display “little intervention,” it is necessary to start with a summary of the disturbances that these ecosystems may experience, considering anthropogenic impacts and natural disturbances.

Sometimes natural or anthropogenic disturbances of watersheds (e.g. fires, landslides, geological processes and ecological succession) can even be decoupled from disturbances in the aquatic system within the same watershed (hydrological cycles and events, a river that has a series of disturbances annually or with greater frequency). In light of this, it is evident that the geomorphology, vegetation cover and hydrology of watersheds can be very diverse along the morphological and bioclimatic gradients of the region. Streams and rivers are also diverse in their morphology at various scales, from a few meters (habitat) to hundreds of meters (stretch of the river) to kilometers. This variability sometimes complicates the interpretation of images from mapping. We propose a basic classification system for intact watersheds located in Patagonia, with the following criteria:

  1. 1.

    Absence of evidence of large-scale fires resulting in massive tree mortality and soil transformation, although the effect of low intensity fire on the understory may be less evident in areas near these large fires.

  2. 2.

    No evidence of large-scale logging or harvesting, although selective logging from many years ago is sometimes difficult to identify.

  3. 3.

    No evidence of road construction or of impacts associated with the entry of heavy vehicles, or of streams crossing over these roads, or the generation of areas of impact on soils due to compaction or erosion.

  4. 4.

    No evidence of the effect of intensive livestock pressure such as trail networks, usually shown by the presence of exotic species associated with livestock (clover meadows, etc.), or artificial wetlands and riparian wetlands being altered by cattle hooves trampling them.

In summary, our definition of an intact forest watershed does not mean that there is no human presence. Rather, the fundamental criterion is that there is no evidence of significant impacts on soils (such as erosion, changes in composition), the water network (drainage, dams, channel modification) or vegetation (changes in horizontal and vertical vegetation structure).

There are unavoidable anthropogenic impacts occurring globally, such as the deposition of atmospheric pollutants and climate change. But these effects are most likely moderate to mild in western Patagonia compared to other parts of the world (e.g. areas of lower atmospheric pollution: [44, 88, 87], and an anomaly in terms of climate change [32, 37].

A photo of a stream running through a rocky path in the woods.

Typical ecosystem of a mountain stream of Nothofagus pumilio (lenga) forests, Lago Atravesado sector, Aysén Region. Photograph by Rubén Isaí Madriz

3 Pristine Forest Watersheds in Western Patagonia

3.1 The Watershed as a Conservation Unit

A fundamental issue in conservation ecology is the planning unit: an endangered species, populations with a disjunct distribution (along with their genetic components), uniform, species-rich forest patches, diverse plant communities and ecosystems are frequently used units. The territorial unit used here, the watershed, is another variant that has few examples to date of being implemented in biodiversity conservation plans [1, 68]. One of the most notable advantages of the watershed as a conservation planning unit is that its topographically defined environment also integrates several conservation elements which are usually considered separately. It includes both the forest and its transition to the zone above the vegetation boundary known as the alpine zone, the riparian zone ecotone, and the aquatic systems as a whole. Not just the river or stream, but the overall water network that feeds the main river and the system that regulates the effects of precipitation events in the river. It involves species, and also a landscape that better encapsulates the possibilities of movement and the set of interactions between species; this is unlike a patch of forest or the arbitrary boundaries of a park or forest reserve. For example, in the watershed there is an altitudinal gradient that includes the ecotones between forest, water and wetland, which may be relevant for the distribution of species sensitive to environmental changes [21, 23, 96] and are equally important for generalist species with wider dispersal ranges. Finally, the above applies both to conservation within a defined space and the downstream effects, connecting diverse ecosystems and human beings.

Given these general criteria as a starting point, watersheds with intact forests (Table 1) are likely to be a much narrower subset, considering only forest area, both in terms of their distribution and area. Assuming that intact watersheds are globally rare and are usually linked to headwater streams that are of great importance in the conservation of biodiversity and downstream ecosystems [1], this intact watershed approach is of enormous value for the global conservation of freshwater systems [62, 102].

3.2 Western Patagonia as a Study Area Based on Its Watersheds

We define western Patagonia as the bioregion of watersheds that originate in the Andes and drain into the Patagonian fjords on the Chilean coast. Our analysis begins in the north in the Petrohué River basin (which discharges at 41.5°S, Los Lagos administrative region), westward to include the island of Chiloé and southward to Cape Horn, 55.91°S. Towards the south it excludes some contiguous forests of Atlantic basins of the Chubut River (north) and Río Grande of Tierra del Fuego to the east (Fig. 2). The area includes the political jurisdictions of the regions of Los Lagos (Palena and Chiloé provinces), Aysén and Magallanes in Chile, and the provinces of Chubut, Santa Cruz and Tierra del Fuego in Argentina. The maximum altitude in the entire region is Mount San Valentín, at 3910 m. The linear distances of river courses from the source to the sea are relatively short, with altitudinal gradients and steep river slopes. The study area includes some of the largest ice fields in the temperate zone: the Northern Ice Field, Southern Ice Field and Darwin Range [97], as well as some of the largest lakes in South America and deepest in the world. Trans-Andean basins are an important feature of the rivers of southern Patagonia, with westward drainage of the Puelo, Yelcho, Palena, Aysén and Baker rivers, while the drainage of the Rio Grande in Tierra del Fuego is eastward through Argentina to the Atlantic Ocean. Small coastal rivers abound in a continental region dominated by extensive fjords and islands (approximately 60% of the Chilean area, Fig. 2, with significant runoff despite the small size of their watersheds. A main characteristic of the region is the strong climatic gradient from west to east, with hyper-humid coastal systems and extreme annual precipitation (>6000 mm/year, to dry and cold steppe systems (<250 mm/year; [94]). The hydrographs of Patagonian rivers vary according to origin, from cold steppes with peak flows from September to October, mountain snowmelt with peak flows from November to December, glacial melt streams with peak flows from January to February, to coastal temperate forest systems with no consistent hydrographs and pulses occurring at any time of the year. The occurrence of this range of hydrographic characteristics is typical for an area the size of western Patagonia.

Fig. 2
A map of Western Patagonia with 23 hydrological units. It has 11 binational watersheds including Puelo, Palena, Pascua, Gallegos, Ciake, and Tierra del Fuego, 6 in Chile including Corcovado and Brunswick, and 6 watersheds including Guaitecas, Taitao, and Torres del Paine.

Map of the large coastal basins, or hydrological and mountain units of western Patagonia that drain into the Patagonian fjords and channels between 41° and 56°S. The different hydrological units are highlighted with numbers (1–23) in the geographic range, and binational basins are highlighted in darker shades

Full size image

3.3 Distribution of Intact Forested Watersheds

Temperate forests in South America are distributed along a long, narrow strip on both sides of the Andes in the western part of the Southern Cone [9]. Of the total area of watersheds with mature forests in Chilean Patagonia (ca., 134,000 km2), 66,000 km2 were identified as intact forested watersheds (IFWs) with no large-scale logging or harvesting interventions, fires or roads (Fig. 3a).Footnote 1

Fig. 3
6 maps of Patagonia. a. Undisturbed forests appear as tiny patches in the south, center, and north. b to d are map fragments with labels including Blanco River, Murta River and San Juan River, Caleta River and Sur River. e. I F W flowing into Elefante Bay. f. Roncagli River basin.

Distribution of the largest undisturbed forested watersheds in western Patagonia (41–56°S). a Areas in green are watersheds mapped as intact (following the methods of Astorga et al. [11]), in red are watersheds or concentrations of larger intact forest watersheds (IFWs). Details in panels b–f from north to south; b Blanco River in Los Lagos Region and headwaters of the Puelo River in Argentina; c Murta River and San Juan River in the Aysén Region; d IFWs in Brunswick peninsula; e Gualas Glacier watershed and several agglomerated IFWs flowing into Elephant Bay, within Laguna San Rafael National Park in the Aysén Region; f Roncagli River basin in the Darwin Range, Magallanes Region

Full size image

The Gualas Glacier watershed (365 km2) in the Aysén Region is considered to be one of the largest intact watersheds; it has low forest cover, but large periglacial areas (Fig. 3e). This is also the case of the Roncagli River basin (234 km2) in the Cordillera Darwin Range, with a forest cover that is mainly limited to valley bottoms and coastal areas (Fig. 3f).

There are also intact watersheds with large forest cover whose waters originate in the Andes, including the Blanco River (190 km2) and the headwaters of the Puelo River (several intact watersheds totaling 389 km2), all in areas that are not included in a formal conservation category (Figs. 3b and 4). Despite its proximity to Punta Arenas, one of the largest cities in Chilean Patagonia, the Brunswick Peninsula conserves large contiguous intact watersheds, with the Caleta River (235 km2), South River (281 km2) and Gold River (256 km2), which flow into the Strait of Magellan (Fig. 3d). Finally, the Murta/San Juan River area (452 and 258 km2, respectively) and Elefante Bay (several contiguous IWCs totaling 479 km2) are very large coastal watersheds with 100% evergreen forest cover that have been conserved without major impacts, due to the characteristics of their forests and because they are difficult to access (Fig. 3c).

Fig. 4
2 maps of the study area and a pie chart. 1. I F W has the largest share, followed by S N A S P E with a few lakes in Chile. 2. S N A S P E dominates, followed by I F W. The pie chart that accompanies has S N A S P E, without protection, and private protection in declining order of their shares.

Distribution and overlap of intact forested watersheds with private (Private Protected Area) and public, National System of Protected Areas (in Spanish SNASPE), conservation categories in the mapping area. Note This map was prepared prior to the declaration of Pumalín and Patagonia Park as SNASPE public areas, and prior to the Rewilding Foundation project in Brunswick Peninsula in 2021

Full size image

The pie chart in the upper right corner indicates the proportion of the area in each conservation category: public protected areas (SNASPE), private protected areas, and unprotected or without any conservation category, which are mainly public lands [75].

According to updates from the National Forestry Corporation’s Native Forest Inventory [24], land use in these intact watersheds was classified with 44.5% as forest, 41.6% as alpine zone (above the tree line) and smaller percentages of wetlands, grasslands and scrubland (Fig. 5). The forest cover within these intact watersheds totals ca. 30,000 km2, with the highest coverage in the Aysén Region, then in the Los Lagos Region and finally in Magallanes, where there is also naturally less forest cover (Fig. 6b).

Fig. 5
A pie chart of the distribution of 6 land cover types in intact. Forest tops with 44.5%, followed by Alpine zone with 41.6%, grasslands and scrublands with 7.7%, wetlands with 4.4%, and others and water bodies with 0.9% each.

Distribution of land cover types in intact watersheds in Chilean Patagonia, according to the National Forestry Corporation’s Native Forest Inventory [49]

Full size image
Fig. 6
3 bar graphs and a scatterplot of watershed frequency distribution. A. Tops at 900 millimeters precipitation. B. By forest types. Aysen tops in evergreen and deciduous. C. By elevation. Tops at 300 meters above sea level. D. Latitude decreases with increasing area. Values are approximated.

Attributes of intact watersheds and their frequency distribution along the bioclimatic gradient. a Distribution along precipitation gradient. b Distribution among forest types, evergreen and deciduous, by administrative region. c Distribution along elevation range. d Latitudinal distribution of IFW area

Full size image

3.4 Biodiversity

The conservation status of freshwater biodiversity is broadly discussed in Reid et al. [95], while in this chapter we address biodiversity on two different levels: (i) one related to ecosystem diversity in intact forested micro-watersheds, analyzing how these intact watersheds are distributed along the bioclimatic gradient of western Patagonia (Fig. 6), assuming that the bioclimatic gradient per se creates patterns of terrestrial and freshwater ecosystem biodiversity; (sii) a review of the state of knowledge on biodiversity associated with the ecotone of the riparian and aquatic zones present in primary forest watersheds in western Patagonia.

3.4.1 First Level: Representation of Ecosystems in Intact Watersheds

The pronounced variation in precipitation across Patagonia represents one of the steepest bioclimatic gradients in the world [38, 110], and is one of the factors that explains the large changes in biodiversity and the composition of vegetation species. The results of the mapping and analysis of the distribution of intact micro-watersheds in the different vegetation types by elevation and bioclimatic zones provide a first look at the diversity of ecosystems present in intact watersheds (Fig. 6). Intact watersheds are mostly distributed in precipitation ranges between 500 and 2500 mm per year (Fig. 6a). The high frequency of watersheds with precipitation between 500 and 1000 mm may be related to the high frequency of micro-watersheds in the lenga (Nothofagus pumilio) forests in the headwaters of western Patagonia’s central valley, which are frequent, but not large (Fig. 6d). Intact micro-watersheds occur mostly in evergreen forests in the Aysén and Los Lagos Regions, while in Magallanes these watersheds occur mainly in deciduous forests (Fig. 6b).

The histogram of elevation frequencies of the intact watersheds is bimodal, with a first peak between 200 and 400 m. and another above 1000 m. in the upper parts or headwaters of the larger continental basins (Fig. 6c). The first peak is related to coastal areas such as Elefante Bay, the watershed of the Gualas Glacier and the San Juan River (Exploradores Valley) whose access is limited, or forest exploitation has been restricted because they are currently included within the Laguna San Rafael National Park conservation unit (Fig. 6c). The second peak corresponds to headwater basins that frequently contain strips of primary forests located above the forest boundary in the alpine zone dominated by sparse high-altitude vegetation, rocks, ice, lagoons and glaciers (Fig. 6c). Wetlands are also present in small headwater basins, especially in mountain rivers (Fig. 1). This tendency is typical of watersheds with forests of mainly lenga (Nothofagus pumilio) and ñirre (Nothofagus antarctica), but not necessarily of the zone of channels and fjords where many streams originate from the forest and have a much less pronounced zonation (Fig. 1).

3.4.2 Second Level: Conservation in Terrestrial and Aquatic Ecosystems

The global biodiversity crisis is the product of anthropogenic threats to forests [115] and inland waters [26, 69]. This section is divided into three subsections: (i) threatened flagship species that are generally the most well-known by the greater public, (ii) preliminary review of the list of species under a conservation category (Species Sheets of the Ministry of Environment, in Spansih Ministerio del Medio Ambiente, MMA) listed for Los Lagos and Magallanes regions, and (iii) preliminary observations on aquatic invertebrate and bryophyte biodiversity in Patagonia.

  1. (i)

    Flagship species

The temperate forest ecosystems of Chile and Argentina are the habitat of several Patagonian flagship species, such as the huemul (Hippocamelus bisulcus), puma (Puma concolor), huillín (southern river otter) (Lontra provocax) and Darwin’s frog (Rhinoderma darwinii), among others. They are defined as flagship species because they are well-known by the public and often promote a general interest in conservation (e.g. Macdonald et al. [64]). A preliminary list of these species is presented in Table 1, together with a summary of the knowledge about them based mainly on a literature review, using keywords (species names) and the species sheets in the MMA database. Some of these species belong to the category of keystone species, defined as generalist species that have wide distribution ranges and require contiguous blocks of habitat with buffer zones and connectivity between landscapes for their conservation (according to Forbes and Chase [30], Echeverría et al. [33]).

The mapping considered micro-watersheds of approximately 1 km2 on average as units of analysis. However, neighboring intact watersheds add up to form extensive landscapes of watersheds with habitats without intervention, reaching surfaces of contiguous areas of approximately 500 km2. The fact that Chilean Patagonia is a naturally fragmented landscape should also be considered. Many animal species show a significant biodiversity turnover in the gradient from the evergreen Valdivian forests to the Patagonian steppe, and they have high degrees of endemism in the different zones [55, 54, 86]. We can consider these aggregated micro-watersheds as larger watersheds, analogous to the concept of “habitat core” [17].

Expeditions by naturalists to Chilean Patagonia indicate that many of the mammal species present today once occupied a greater diversity of habitats, including river valleys, forests, and mountainous areas [39, 84]. The geographic range of several flagship Patagonian species in Chile and Argentina has been described as much more extensive latitudinally than longitudinally. Impacts generated from the twentieth century onwards by fires, erosion, cattle ranching, and urban centers resulted in losses of these large continuous areas of intact landscapes and forests in western Patagonia [57, 77]. The distribution of several flagship species of Chilean Patagonia has receded to the last inaccessible habitats with little intervention in the upper parts of the watersheds, and in some cases to environments unfavorable for their populations. This may be the case of the huemul, considered a species of high mountains and extreme zones [51, 97], but during the early stages of European colonization, its presence was greater in the productive valleys in the vicinity of Coyhaique such as Simpson River [67].

  1. (ii)

    Species with conservation problems

The list of species in the precarious conservation category [76] between Los Lagos and Magallanes Regions of Chile includes 367 taxa, of which more than 100 are associated with aquatic ecosystems: rivers, streams, lakes, wetlands, large rivers and transition from freshwater to coastal systems. Most of these species are discussed in detail in Reid et al. [95]. Below, we refer in particular to terrestrial species listed in some conservation category in the MMA Species Sheets, which are often associated with riparian zones. The list includes 30 species of fungi (22 genera), including the two species of Cyttaria, known as “Indian bread,” which parasitize living trees and probably face the same threats that affect forests. However, the diversity of fungi in Patagonian forest systems is still poorly studied. There are 52 species of ferns, many of which are epiphytes (e.g. Grammitis and Hymenophyllum spp.). This diversity of pteridophytes is also mainly associated with intact forest systems [89]. The only vascular plant species associated with streams in forests is Hebe salicifolia, although its relationship with intact systems is not clear. One noteworthy point is that ferns outnumber vascular plants (35 species) and that plants, such as Juncaceae and the graminoids require more effort for taxonomic identification; Poaceae and Cyperaceae are virtually absent (B. Reid, personal observation). This is probably an indication of the lack of more complete studies and/or assessments of the conservation status of this flora, at least in remote locations (with the exception of Tierra del Fuego, Moore [78]. An alternative explanation may be that ferns are better represented in the Patagonian flora, as is the case for lichens and bryophytes [82, 83, 99].

We should not only consider flagship species, or species already recognized as species with conservation problems, but also the diversity of lesser-known groups whose potential species richness indicate that they are possibly the ones that contribute most to regional biodiversity. We refer to aquatic insects, mosses, ferns, lichens and freshwater algae [58, 80, 85]. Unfortunately, knowledge of these species in the mapped ecosystems is still very poor.

  1. (iii)

    Freshwater species richness

Aquatic species richness is concentrated in insects (Plecoptera, Ephemeroptera, Trichoptera), crustaceans (Aegla and Hyalella), gastropods and bryophytes [95, 108,109,108]. The diversity of these groups in Chilean Patagonia has been described as slightly lower than in the Valdivian region [109]. Many taxonomic groups undoubtedly reach the southern limit of their geographic range in the latitudinal gradient of Chilean Patagonia, although there has been less sampling effort than in regions farther north [80, 85]. Freshwater diversity along east–west bioclimatic gradients in less accessible watercourses such as headwater streams and in the island and fjord region is represented with very few examples [95]. A prominent exception is research conducted in Magallanes, primarily on Navarino island, where macroinvertebrate biodiversity has been described in aquatic systems in steep elevation gradients with very little intervention [22, 21, 96].

Preliminary results on macroinvertebrate diversity in headwater streams with watersheds dominated by primary forests in Aysén indicate a total of 89 species, of which almost 40% had not been recorded before in the region [85, 108]. Preliminary results indicate that macroinvertebrate diversity in 102 micro-watersheds studied to date is strongly related to natural climatic and hydrological variation among basins [12]. Among the climatic variables that best explain macroinvertebrate diversity are regional precipitation and temperature gradients [12]. Forest cover and hydrological properties of the channel are closely related to the composition of stream invertebrates [12]. The latter is probably related to an altitudinal gradient and the origin of the stream (e.g. alpine zone or forest).

Biodiversity studies of bryophytes carried out in the riverbeds and riparian zone of the micro-watersheds of the headwaters of the Aysén rivers and lake General Carrera identified 258 taxa: 3 anthocerotes, 101 liverworts (100 species and one variety) and 154 mosses (153 species and one variety). Two of the species are new records for Chile: the liverworts Austrololophozia andina R.M. Schust. and Riccardia theliophora Hässel.); 41 are new records for the Aysén Region; 105 are new records for the General Carrera province; 77 are new records for the Coyhaique province and 22 are new records for the Aysén province [48, 58, 82, 83], in addition to one new record for science (Syntrichia lamellaris, Gallego et al., [106]). These results show us that the distribution of bryophytes in the Aysén Region, as well as in other sectors of Chilean Patagonia, is still poorly known, as is true for other taxonomic groups as well.

The analysis of Reid et al. [95] complements this biodiversity section on two important topics: (i) it discusses the literature review of other freshwater taxonomic groups associated with headwater streams, such as amphibians and native fishes, which also contribute to watershed conservation values, (ii) it refers to the state of knowledge of invasive exotic species, which are currently affecting freshwater systems in western Patagonia, such as salmonids, mink and beaver among vertebrates, and among plants, species such as lupine (Lupinus polyphyllus) and willow (Salix fragilis), which are invading riparian zones and larger riverbeds [60, 72].

3.5 Threats

The forested watersheds of western Patagonia with little intervention provide valuable ecosystem services such as drinking water supply and irrigation, flood control, provision of habitat for biodiversity, carbon sequestration and cultural services, which collectively can provide economic and non-economic values for local communities [14]. These services in Chilean Patagonia are threatened by the impacts of human activities, including the introduction of invasive species, fires, cattle ranching, road construction and the unsustainable use of timber resources, added to the effects of global climate change [66]. These processes have gradually led to habitat degradation and fragmentation, soil erosion, the spread of invasive species, pollution and overexploitation of forests [40]. The most serious threats currently facing these ecosystems are detailed below.

3.5.1 Climate Change

Climate projections based on global and regional models are generally rather uncertain for the complex terrain of the region [59, 112]. Temperature increase is expected to be less, in part due to regional cooling of ocean temperatures [32, 38, 37]. Effects on the headwater stream temperature may be weak due to this oceanic climate, but water temperature also depends on rainwater input and snowmelt, and this equilibrium (snow line or zero isotherm) is changing across the region, based on local observations [46]. Historical data in the region exhibit a decreasing trend in precipitation in recent decades [5]. Unfortunately, current regional climate models do not clarify the uncertainties of the projections, since a significant portion of the Chilean Patagonian region is located in a transition between areas of decreasing (Los Lagos Region) and increasing precipitation (Magallanes Region) that also vary between the east and west [31]. Specific changes in precipitation and temperature in Chilean Patagonia will affect forest regeneration, hydrology, erosion, soil quality and alpine zone boundaries, among others [66].

3.5.2 Timber and Firewood Extraction

One of the most intense current anthropogenic pressures on the forested watersheds of Chilean Patagonia is firewood extraction. The Los Lagos and Aysén regions are home to the greatest expanses of native forests, and the extraction of firewood and timber is also the most intense, mainly large volumes of lenga (67%) and ñirre (31%). Coihue (Nothofagus dombeyi), pine, and tepa occupy the remaining 2% (Ministry of Agriculture [73, 74]; in Spanish Ministerio de Agricultura). Timber extraction is generally carried out on roads that frequently cross or run parallel to bodies of water, leading to soil erosion and sedimentation in streams during rain events. This sediment load in streams affects primary production, habitat availability and aquatic biodiversity [3]. Such effects could be exacerbated by changes in precipitation and seasonality [32, 31, 38], as many of the slopes and streams without vegetation cover could be eroded.

Energy needs are met in the Aysén Region by the use of firewood (approximately 687,000 cubic meters of firewood are consumed annually), but only 40% of the harvest has a management plan. The largest volumes of firewood and timber are harvested near population centers [105]. The forests that supply the city of Coyhaique, the capital of the Aysén Region, with firewood, for example, include the areas of Lake Pollux and Frío, Cerro La Virgen, Cerro Galera, and Villa Ortega, among others [98, 105]. As timber resources are depleted, the distance to the harvest centers increases and the area moves towards the high-altitude forests.

Atmospheric pollution due to the intense domestic use of firewood, plus the thermal inversion effect that occurs during fall and winter months in Coyhaique (April–August) have made the city the most polluted in Latin America in some periods, according to data analyzed by the World Health Organization between 2013 and 2016 (The Guardian, May 12, 2016). The government enacted the first Environmental Decontamination Plan (PDA in Spanish) for the area in 2015. This plan involves several measures aimed at diversifying the energy grid, improving the thermal insulation of homes, replacing heaters and environmental education, to improve air conditions in Coyhaique and other urban centers in the region. The long-term plan could also theoretically reduce threats to Aysén’s intact forested watersheds.

3.5.3 Loss of Connectivity and Fragmentation

One of the greatest threats to the large tracts of intact landscapes in western Patagonia is the expansion of the road network. The growth of the road network allows access to primary forests that for cost reasons were excluded from timber production, facilitating the entry of livestock and other exotic animals, and generating impacts that accelerate their exploitation and degradation [56, 91]. The network of logging roads has also been shown to have negative impacts on river channels, changing channel geomorphology and sediment loads in watersheds [116]. In Chilean Patagonia these problems are due to poor territorial planning, which should consider not only the need for connectivity, but also the conservation status of terrestrial ecosystems and watersheds crossed by roads. An example of this urgent need for planning and zoning is the Special Development Plan for Extreme Zones, where the Agricultural Development Institute (in Spanish INDAP) has established a special road construction program with a budget of 3 billion Chilean pesos that proposes to build a total of 550 km of roads connecting properties within three years [17].

3.5.4 Summer Livestock Grazing in Headwater Watersheds and Alpine Areas of Public Lands

As has been said, headwater streams in forests with little intervention safeguard the quality and quantity of water and the integrity of aquatic ecosystems downstream, but their usefulness is undermined by the use of equally pristine, but much more fragile areas in the alpine zone. A clear example is the management and control of summer grazing. This activity takes place in pastures belonging to the State located in the high-altitude mountain areas, which are used only four months a year due to climatic characteristics (Ministry of National Asssets 2018; in Spanish Ministerio de Bienes Nacionales, MBN; and personal communication). The MBN currently grants permits for use; however, there is no regular oversight of uses and impacts. Summer livestock grazing is a culturally rooted practice in the region, on public and inaccessible lands where indiscriminate use is made of the resources of an area where the watershed’s watercourses are born. The lack of management results in the degradation of vegetation resources, native fauna, and water sources.

4 Conclusions and Recommendations

Headwater basins could be likened to water towers; objects in the landscape that capture, store, and deliver water to downstream ecosystems, both those with little intervention and those with more intense productive use. Although freshwater ecosystems are among the most threatened in the world, their point of greatest vulnerability is their origin in the upper parts of the mountain range, where small, crystalline, meandering streams are born. When these streams pass through forests, the risk of losing their integrity increases due to the demand for wood products, such as firewood, as well as road construction, especially in the temperate biome. Therefore, intact forested watersheds should be among the primary targets for freshwater and intact landscape conservation (Fig. 4).

According to our analysis, the watersheds with forest cover that drain into the Patagonian fjords and the Pacific represent a great opportunity for global conservation, but a significant portion of them are outside existing protected areas. In this chapter, information on the specific biodiversity of these ecosystems was presented and discussed, highlighting the limited knowledge of the species present there and their natural history. The analysis of the spatial distribution and bioclimatic diversity of these systems is now available for planning [90] and redefining conservation priorities.

Although Chilean Patagonia has approximately 50% of its total area under some category of conservation, the unprotected areas contain approximately half of the intact forested watersheds mapped in this research (Fig. 4). These watersheds without major interventions also contain some of the ecosystems most vulnerable to climate change and land use change, the headwater watersheds together with their mature primary forest, stunted and alpine zone ecosystems (Figs. 4 and 5). Therefore, we present the following recommendations for conservation and sustainable use:

  • Ensure that public policy and/or regional conservation and land use planning instruments recognizes the importance of the watershed concept which integrates water, forests, and soils. This should be accompanied by a system of incentives to landowners in order to effectively conserve the most pristine or valuable areas for their biodiversity, together with improved management and related public policies. More specific mechanisms for these purposes could be, for example.

  • Forest management plans or recreational use plans in the SNASPE should include the micro-watershed as a planning and zoning unit, considering the connection between water, forests, and soil.

  • Fodder subsidies are required as an alternative practice to high-altitude summer livestock grazing, along with improvements in the registry/mapping of active summer grazing areas and carrying capacities.

  • Protection of wetlands associated with headwater streams is required, starting with a wetland registry for this region [65, 95].

  • Implementation of integrated management pilot projects in small watersheds (10–30 km2), which due to their size and lesser degree of conflicts between different uses have a greater chance of success. At the same time, valuable experience could be gained in carrying out planning and conservation projects on larger scales, for example, pilot programs in watersheds that provide drinking water in rural communities, where planning and/or zoning of uses has a direct impact on the quantity and quality of drinking water. It is also necessary to develop local models for the provision of ecosystem services (including payment for these services) in different land use scenarios of watersheds [4].

  • Chile-Argentina binational efforts. Conservation of watersheds has to respect hydrological boundaries and not just political ones, as in freshwater biodiversity conservation [95]. There is a large percentage of binational headwater watersheds that contribute to the large rivers that flow into the fjord zone of Chilean Patagonia (Fig. 2). Binational conservation management in Patagonia would be more effective in several aspects related to freshwater biodiversity, along with the idea of anticipating conflicts.