The mammal community of the Coastal Range of southern Chile has been little studied even though they inhabit an environment under severe threats due to anthropic disturbance. During the spring-summer seasons of 2020–2021 and 2021–2022, we characterized the communities of wild terrestrial mammals in a native forest (NF) and an exotic plantation of Eucalyptus (PL) of the Coastal Range of Osorno province by phototrapping. We used 1,060 camera-trap days in the NF and 960 camera-trap days in the PL to explore the effect of habitat type on wild mammal diversity in two localities (L-1 and L-2). We quantified the species richness, abundance, community similarity and daily distribution of mammal communities. Species richness was higher in the NF (7–8 spp) than in the PL (3–4 spp). Two community similarity index (CSI) was significantly higher between native forests (CSI = 0.728 ± 0.088) than between Eucalyptus plantations (CSI = 0.211 ± 0.097) (95% CI). Mean abundance was also higher in the NF than in the PL (L-1: 0.011 vs. 0.004 occurrence/camera-trap day (OCT); L-2: 0.008 vs. 0.004 OCT). In L-1, the most abundant mammals in the NF were Leopardus guigna (45.3% of relative occurrence (RO)) and Pudu puda (18.9% RO), and in the PL, they were Lycalopex culpaeus (50% RO) and L. guigna (37.5% RO). In L-2, the highest abundances in the NF were for P. puda (34.5% RO) and Puma concolor (27.6% RO), while in the PL, P. puda was predominant (66.7% RO). In NF of both localities, 22.2% of melanic L. guigna individuals were observed. The highest frequency of occurrences in both locations was between 12:00 and 23:59 hours, with 60% and 76.9% of detections, respectively. The species richness found in native forest is in accordance with studies carried out in other temperate rainforests of southern Chile. In addition, native forests support a richer and more similar community of terrestrial mammals than exotic forest plantations, which indicates that native forests are the main habitat for most mammals detected and that exotic plantations function as a complementary habitat for some species.

abundance, biodiversity, camera traps, community similarity, species richness

Assessing mammal richness in the temperate rainforest of southern Chile (39 to 44°S) is important to increase the knowledge of the spatial use of forest habitats by the mammal fauna in this geographic area and understand the temporal dynamics of the mammal assemblages. This information is relevant for conservation purposes given that the native forest in the Coastal Range of southern Chile contains plants and animals with a high level of endemism; as a result, this area represents a biodiversity hotspot of global importance (Myers et al. 2000; Nahuelhual et al. 2007). However, despite their importance for the conservation of biodiversity, at local and global scales, these forest formations have endured a rapid rate of destruction and degradation due to anthropogenic causes (Myers et al. 2000; Echeverría et al. 2006, 2007). For example, according to Lara et al. (2012), the loss of native forest in the Los Ríos and Los Lagos regions, was a consequence of 25% of their area being replaced by grasslands and 27% by bushes. In addition, the fragmentation process of the native forest distributed in southern Chile during recent decades along with their replacement by exotic plantations for wood production is another factor of particular concern (Echeverría et al. 2006, 2007). In fact, in Osorno Province between 2006 and 2013, the area with exotic plantations increased significantly (+20.6%), a large part of this growth being at the expense of the original native forest (CONAF-UACh 2014).

The Coastal Range of the Los Ríos and Los Lagos regions in southern Chile is an area that comprises 683,694 ha (39°24'–41°45'S latitude) and harbors a typical and relatively well-preserved coastal temperate forest (Pliscoff et al. 2005). In particular, the Osorno Province, which is located in the northern part of the Los Lagos Region, approximately 42.9% of the area contains native forest (CONAF-UACh 2014), mostly distributed in the Coastal and Andes mountain ranges (Miranda et al. 2017). The Coastal Range contains a high level of endemism and a great representativeness of ancient phylogenetic lineages, and, due to these characteristics, it was declared a priority site for the conservation of biodiversity by the Ministerio del Medio Ambiente (MMA 2022) of the Chilean government. However, this geographic area is highly threatened by exotic plantations, illegal logging and forest fires.

Studies carried out on mammal diversity in the Coastal Range of southern Chile are limited since the number of monitored geographic areas has been relatively scarce, which makes it difficult to establish clear distributional patterns of species (Smith-Ramírez et al. 2019). Most studies carried out in this geographic area have focused mainly on birds, lizards and amphibians, and mammals were the least studied group of terrestrial vertebrates. Thus, increasing the knowledge about the mammal diversity of the Coastal Range of southern Chile is relevant to provide data on species richness to aid the conservation of mammal diversity in the coastal native forest. This is especially important for the species that are most susceptible to extinction in the short term and endemic to a restricted geographical area or that have reduced population sizes (Höglund 2009; Isik 2011). In this way, evaluating the diversity of wild mammals fauna in the temperate rainforest of southern Chile represents a contribution to the world efforts dedicated to nature conservation (Mittermeier et al. 2005), especially in areas with high human perturbation.

There have been a number of ecological studies on native mammals inhabiting temperate rainforests in southern Chile; however, most of them have focused on individual species (e.g., Rau and Jiménez 2002; Rodas-Trejo et al. 2010; Silva-Rodríguez et al. 2010; Sade et al. 2012; Skewes et al. 2012; Gálvez et al. 2013; Delibes-Mateos et al. 2014a). Despite this progress, the analysis of terrestrial mammal communities inhabiting temperate rainforests in southern Chile has been less addressed (Delibes-Mateos et al. 2014b; Sanino et al. 2016). These studies have been carried out in a limited number of sites of temperate rainforests, and further studies are necessary to increase the information on terrestrial mammal diversity to gather a more complete view of their habitat use. Nonetheless, these studies have reported interesting data on species richness, ranging from eight to ten species, and abundance of terrestrial mammals that inhabit some reserves (Delibes-Mateos et al. 2014b; Sanino et al. 2016).

Studies on wild mammal diversity in exotic forest plantations distributed in Chile have been less addressed. This issue is relevant given that, in Chile, large areas of native forest have been replaced with exotic forest plantations for commercial production (Miranda et al. 2017), and little is known about their effect on mammal diversity. Understanding the responses of wild mammals to exotic forest plantations is relevant to assess the effectiveness of environmental practices implemented by the forest industry, which is usually supported by the certification process (in our country, the Forest Stewardship Council (FSC) and the CERTFOR/PEFC Chile). There is increasing evidence supporting the negative effect of exotic forest plantations on mammal diversity in some South American countries (Umetsu and Pardini 2007; Pardini et al. 2009; Rodas-Trejo et al. 2010; Rosa and Vieira 2010; Grazzini el al. 2021). In fact, in Eucalyptus forests, an impoverished community has been observed when compared to native patches (Gheler-Costa et al. 2012). Other reports show that the number of species using forest plantations is almost half of those using native patches (Hobbs et al. 2003), with small mammals showing small richness and abundance of forest plantations in the neo-tropics (Prevedello and Vieira 2010; Martin et al. 2012; Grazzini el al. 2021). There is also evidence that species richness and abundance in exotic forest plantations are greater in areas closer to native vegetation remnants, which may be related to the positive ecotone effect (Barnett et al. 1977; Friend 1982). However, there are several studies that show that plantation forests may provide valuable habitat for species, whose use is highly dependent on the species, community and landscape structure (Brockerhoff et al. 2008). In Chile, it has been stated that a well-developed understorey in exotic forest plantations has been indicated as possibly useful as a surrogate habitat for native species, thus mitigating the negative effect of forest plantations on species richness (Simonetti et al. 2013). In Brazil, the presence of the understorey in exotic forest plantations has been identified as an important factor determining the species diversity (Stallings 1991; Rosa and Vieira 2010). Experimental data obtained in central Chile support the positive effect of well-developed undergrowth of pine plantations on the occurrence of native mammals, such as, Leopardus guigna, Lycalopex culpaeus, Conepatus chinga, and Pudu puda (Simonetti et al. 2013). Other studies carried out in southern Chile indicate that in geographical areas that contain mixed forest (exotic plantations of Eucalyptus and native forest), some carnivores, such as Puma concolor and Pseudalopex griseus, positively select the native forest, avoiding exotic forest plantations as a complementary habitat (Rodas-Trejo et al. 2010). However, contradictory results were reported in pine plantations distributed in this geographical area (Zúñiga et al. 2009).

Our study aimed to characterize and compare the communities of wild terrestrial mammals inhabiting the native forest and the exotic forest plantation of two localities of the Coastal Range of the Osorno Province, southern Chile, to explore the effect that these two types of environment have on wild mammal diversity. Considering that the available evidence indicates that exotic forest plantations are less suitable for native mammal species (Umetsu and Pardini 2007; Pardini et al. 2009; Rosa and Vieira 2010; Rodas-Trejo et al. 2010; Grazzini el al. 2021), we hypothesize that exotic forest plantations of Eucalyptus will present a reduced richness and diversity than native forests.

The result of species richness recorded in this study for the terrestrial mammal communities found in the native forest of the Coastal Range of Osorno Province, is similar to that reported in studies conducted in other geographical areas of southern Chile. In fact, the species richness found in Huellelhue Community and Los Riscos, which varied from seven to eight species, it is within the range reported in other temperate rainforests of southern Chile. For example, Sanino et al. (2016), using camera-traps, also reported eight species belonging to the orders Carnivora, Artiodactyla and Rodentia in the Añihué Reserve in the northern part of the Aysén Region (43°48'S, 72°58'W). In addition, Delibes-Mateos et al. (2014b) reported 10 terrestrial mammals in temperate rainforests of southern Chile located in the Huinay reserve of the Los Lagos Region (42°22'S, 72°24'W) using three detection methodologies (questionnaires to residents and visitors, transects of mammal presence and camera-trapping). We recorded the presence of three species of carnivores in the native forest of the studied area, namely P. concolor, L. culpaeus and L. guigna. The abundance of these species was relatively high in the studied area, varying between 0.002 and 0.041 occurrences/camera-trap days, with L. guigna being the most abundant species among all the carnivores identified with 0.041 occurrences/camera-trap days. The abundance of L. guigna is similar to values reported for this parameter in studies carried out in areas further south of our study sites. For example, in the Añihue Reserve this feline presented a value of 0.034 occurrence/camera-trap days (Sanino et al. 2016), and in Huinay Reserve, this species showed a value of 0.035 occurrence/camera-trap days (Delibes-Mateos et al. 2014b). However, our result of abundance is higher than that reported by Gálvez et al. (2013), who reported only 0.001 occurrences/camera-trap day for L. guigna distributed in fragmented native forest located to the north of our study area during spring-summer of 2008–2009 (Pucón district, La Araucanía Region). Therefore, the high abundances of L. guigna observed in the study areas may be related to their relatively good conservation, which emphasizes the importance of maintaining a large surface area of undisturbed native forest to better conserve this emblematic and near-threatened (MMA 2022) carnivorous species. In addition, it is likely that the diminished presence of a dense understorey in exotic Eucalyptus plantations is a factor that limits the presence of melanic L. guigna in exotic forest plantations. This is a possible explanation given that L. guigna is a species with a wide home range, of approximately 261 ha (Dunstone et al. 2002), a characteristic that would potentially allow them to colonize exotic forest plantations close to native forests. In addition, from the conservation point of view, Eucalyptus plantations would be an unsuitable habitat for the long-term conservation of the different fur color phenotypes of L. guigna.

Our results show that the abundance of terrestrial mammals in the native forest was higher than in the exotic plantations. In fact, in the Huellelhue Community sector, the mean abundance in the native forest was 0.011 occurrences/camera-trap days, while in the Eucalyptus plantation of Putrihue this parameter reached a value of 0.004 occurrence/ camera-trap days. This result is consistent with previous studies of the abundance of carnivores, for example, P. concolor and P. griseus, among mature and recent plantings of Eucalyptus versus existing native forest in the Purranque district, a study that showed a positive and significant selection for the native forest habitat and a negative selection for the recent plantations of Eucalyptus (Rodas-Trejo et al. 2010). However, our results differ from those published by Zúñiga et al. (2009), who found that puma and chilla fox in the Araucanía Region (Rucamanque site) preferentially select pine plantations over the native forest. Therefore, it appears that the non-use of exotic forest plantations by pumas and foxes depends on their vegetation structure. Several factors may determine the use of pine plantations by native mammals. For example, there is evidence that a well-developed understorey in pine plantations is an important attribute that favors the presence of foxes and other mammals in Central Chile (Simonetti et al. 2013). This is also consistent with the results of Rosa and Vieira (2010), who reported that the understorey positively influenced the presence of small mammals in pine plantations of Rio Grande do Sul, Brazil.

We expected exotic plantations to present lower species richness as reported in previous studies (Umetsu and Pardini 2007; Pardini et al. 2009; Rodas-Trejo et al. 2010; Rosa and Vieira 2010; Grazzini et al. 2021). Our results support this hypothesis given that species richness was significantly lower in the exotic plantations than in native forest in the two analyzed localities. In addition, community similarity measures revealed that, between the Eucalyptus plantations, the species composition was more dissimilar than between the native forests, indicating that mammal communities of native forests have a higher composition resemblance than that of exotic plantations. This result is consistent with the available evidence since in exotic plantations and reforested forest areas assemblages are usually distinct (Umetsu and Pardini 2007; Pardini et al. 2009; Rosa and Vieira 2010; Grazzini et al. 2021). Therefore, these results support that exotic plantations of Eucalyptus negatively affect the local diversity of the terrestrial mammal in the Coastal Range from southern Chile.

In addition, we observed species with some preference for Eucalyptus plantations over native forests, in particular, L. culpaeus and C. chinga. P. puda followed a similar pattern, given that their abundance was quite similar between both habitats in Los Riscos. These results reveal that these species expressed high plasticity in their habitat use, allowing the use of native forest and Eucalyptus plantations. Although further monitoring efforts with camera traps will be required to better support this pattern, it is likely that exotic forest plantations could have compositional characteristics that favor the presence of these species. Some studies have indicated that the presence of an understorey could be a relevant factor that influences diversity of mammal species in both Eucalyptus plantations (Stallings 1991) and pine plantations (Rosa and Vieira 2010; Simonetti et al. 2013). In fact, experimental data obtained in central Chile support the positive effect of a well-developed undergrowth of pine plantations on the occurrence of different native mammals, including P. puda (Simonetti et al. 2013). Thus, in the analyzed localities, the Eucalyptus plantations may function as a surrogate habitat for some mammal species, mitigating to some extent the negative effect of plantations on species richness. In addition, the process of surrogation of the Eucalyptus plantation may also be associated with the generalist feeding of these species, which may determine their tendency to occupy disturbed environments. This explanation is plausible given that available data indicate that L. culpaeus and C. chinga are generalist species (Donadio et al. 2004; Medina et al. 2009; Lobos et al. 2020). In Brazil, the positive effect of Eucalyptus plantations on the abundance of small mammals, especially the more generalist species, has also been observed (Rosalino et al. 2014).

The detection of the species in native forest of the Huellelhue Community was concentrated mainly between 12:00 and 23:59 h, while the greatest diversity of occurrences in this same area occurred between 12:00 and 17:59 h, with at least four species. The same pattern of sightings and diversity of occurrences was observed in the Los Riscos sector. These results are consistent with the nocturnal behavior of Chilean mammals (e.g., Jaksic and Simonetti 1987; Iriarte 2010; Delibes-Mateos et al. 2014a). In particular, P. puda showed an increase in activity during twilight, which could be part of an evasion strategy against diurnal predators. L. guigna also showed greater crepuscular activity both in the native forest and in Eucalyptus plantation. Although additional studies are required to confirm the existence of this pattern, studies in other areas of native forest in southern Chile, such as that carried out in the Huinay Biological Reserve (Hernández 2010, Delibes-Mateos et al. 2014b), indicate that its occurrence could be related to a greater availability of small mammal prey during twilight.

Finally, the existence of melanism in L. guigna is a phenomenon of common occurrence in Chile, whose incidence in different populations distributed in the national territory varies from 0% to 90.9% (Sanino et al. 2016). Some authors have related the level of incidence of melanism with the increase in the geographical latitude of the populations (Miller et al. 2015), which seems to be related to the decrease in environmental temperature in sites located at higher latitudes (Sanino et al. 2016). Our data showed a 22.2% melanic individual incidence that agrees with values of melanism incidence observed in populations distributed in similar latitudes, such as those inhabiting the Senda Darwin Biological Station (28.6%, Sanderson et al. 2002) and the Isla Grande de Chiloé (15,8%, Napolitano 2011). However, this level of L. guigna melanism was discordant with respect to those found in populations distributed further south of the country, such as those of Huinay Reserve (50%, Delibes-Mateos et al. 2014b) and the Añihue Reserve (48,1%, Sanino et al. 2016). Thus, our results add support to the belief that the frequency of melanism in L. guigna vary as a function of the latitudinal location of the populations. Likewise, a higher frequency of melanic L. guigna in colder areas of southern Chile is probably related to an adaptive advantage provided by this phenotype in densely forested environments. Melanic fur can provide greater camouflage capacity, rendering them less visible to prey and favoring their hunting process. In fact, in South American felids the presence of specimens with melanic fur has been related to a greater adaptive advantage in certain environments compared to typical fur (Schneider et al. 2012). In our study area, the native temperate forest has an understorey composed mainly of a dense layer of quila (Chusquea quila) and various species of ferns (e.g., Lophosoria quadripinnata and Blechnum chilense) (Luebert y Pliscoff 2006), with a low incidence of light at ground level, favoring the melanic phenotype of L. guigna. This could also explain the reduced detection rates of melanic L. guigna in the Eucalyptus plantations, probably because this habitat lacks a dense understorey, increasing the light intensity at ground level and, thus, the visibility of melanic individuals. Therefore, it is likely that the diminished presence of a dense understorey in exotic plantations of Eucalyptus deters the presence of melanic L. guigna, a finding that is more striking when we consider that individuals of different fur color phenotypes could migrate to this habitat, as this species has a wide home range (approx. 261 ha, Dunstone et al. 2002). However, from the conservation point of view, exotic plantations of Eucalyptus would be an exotic habitat that is not very favorable for long-term conservation of the different fur color phenotypes of L. guigna.

Our results support that exotic plantations of Eucalyptus reduce the local diversity of the terrestrial mammal of the Coastal Range from southern Chile. This result highlights the importance of increasing the efforts aimed at the conservation of native forests and strengthening reforestation policies as a strategy to reduce the effect of exotic forest plantations on native mammal diversity. This issue is not trivial, given that native forest in southern Chile has experienced an important reduction during recent decades (approximately -25%, Lara et al. 2012), a process that is likely to continue due to different factors, such as illegal logging and forest fires. However, it appears that exotic plantations of Eucalyptus have compositional characteristics that favor the presence of some native species in this habitat (e.g., L. culpaeus and P. puda), a pattern that has been observed in other localities of Chile and in mammalian communities inhabiting other countries of South America. However, Eucalyptus plantations appear to affect the presence of melanic L. guigna, which reveals that this habitat is unsuitable for the long-term conservation of the different fur color phenotypes of this species. Considering that Eucalyptus plantations will continue to exist given their economic importance in the national forest industry, forestry companies should implement specific management practices to protect the native mammal fauna that inhabits these areas as a surrogate habitat.

We thank Masaharu Takai, Forestry Legal and Regulation Assistant Manager and Heriberto Marchant Veláquez, Professional Expert in Risk Prevention, both from the company Anchile Ltda, for facilitating the installation of the camera traps in the Eucalyptus plantation from Putrihue and Los Riscos property. We also thank Mr. Luis Quintul, a resident of the Huellelhue Indigenous Community, for guiding the field work in the native forest sector near this community.