Watersheds and Trees Fall Together: An Analysis of Intact Forested Watersheds in Southern Patagonia (41–56° S)

Abstract

While intact forests have intrinsic value in terms of conserving biodiversity, they are also important for associated ecosystem services of soil and water conservation, in addition to the biodiversity, function and geomorphology of stream and river ecosystems. In this latter context, the perspective of watershed is more relevant than forest patch, however we are unaware of any landscape assessments of intact forested watersheds (IFWs). We mapped the coverage of forested watersheds with limited intervention for southern Patagonia (Chile, Argentina) using existing forest stand mapping and high resolution stream/watershed delineation (patch size~0.4 km 2 ). Validation and adjusted IFW boundaries was performed using high resolution satellite imagery for three major inland basins representing the north-south range of the study area. For both scales we evaluated size distribution, conservation status, forest type (deciduous vs. evergreen temperate forest) and bio-climatic zones (precipitation range 500 to >6000 mm/year). For the coarse regional analysis potential IFWs covered over 40% of land surface, and included nearly 60% of all forest cover. These figures were significantly reduced following basin scale validation to 6-21% for IFWs and 5-14% of forest contribution to IFW. IFWs identified in the regional analysis were lower elevation (0-100 m) due to abundant coastal drainages, whereas the basin analyses were higher elevation headwaters systems (1000+ m), the largest over 80 km 2 . Total IFW cover was estimated between 50,000-132,000 km 2 , the range a reflection of disparate results across these two scales, further highlighting the need for comprehensive revision and field validation. At the same time the difference in areas, defined mostly by minor levels of intervention, indicate the vast potential for management or restoration. Taken together they represent a nationally and globally significant contribution to of intact temperate forests and IFWs. Interactions between forest and stream ecosystems, and their implications for IFW conservation, are discussed in these contexts, based on examples from the region. Finally we used Getis-Ord Gi* statistics to identify hot and cold spots for different attributes, providing an example of a combined index for prioritizing IFW conservation.

Seasonal Partitioning of Rainfall in Second-Growth Evergreen Temperate Rainforests in Chiloé Island, Southern Chile

“…Temperate rainforests of southern South America occur along the western land-ocean margin, with a mean distance to the ocean of 250 km between 37 and 55 • S (Aravena et al, 2002;Astorga et al, 2018). South American temperate rainforests are under a strong oceanic influence, having high relative humidity and low temperature oscillation throughout the year.…”

Climate and Land Cover Trends Affecting Freshwater Inputs to a Fjord in Northwestern Patagonia

“…Nevertheless, using rivers like Puelo River as sentinels, several studies have reported anomalous events in fjords of northwestern Patagonia (e.g., surface hypoxia events, harmful algal blooms), mainly during severe droughts (Valle-Levinson et al, 2007;León-Muñoz et al, 2013Iriarte et al, 2017;Díaz et al, 2021). Although northern Patagonian basins have not yet been modified by irrigation channels or reservoirs and still maintain extensive little-degraded native forest cover (CONAF and UACH, 2014;Astorga et al, 2018), recent threats such as increased wildfires and their joint effect with climate change have not been evaluated hydrologically to date. Considering this context, here we evaluate the influence of climate and land cover trends on the freshwater inputs of the Puelo River Basin to the Reloncaví Fjord (41.5 • S; Figure 1).…”

A systematic evidence map of conservation knowledge in Chilean Patagonia

“…This biogeographic context promotes high levels of endemism and diversity of species supporting key ecosystem services (Rozzi et al, 2012), such as climate regulation, carbon storage, freshwater provision, and cultural diversity heritage. The region has one of the most continuous forest covers (120,000 km 2 ) and the largest area of peatlands and wetlands (42,000 km 2 ) representing the main carbon sink and carbon storage source in the southern hemisphere contributing to climate change mitigation (Astorga et al, 2018; Mansilla et al, 2021; Ministerio del Medio Ambiente, 2020; Rozzi et al, 2012). It is a global freshwater reserve because of the presence of the world's third‐largest ice fields, and there is a rich diversity of cultures and languages represented in particular by distinctive rural cultures and indigenous populations (Aylwin et al, 2021).…”