Abstract
Polylepis (Rosaceae) is the dominant tree genus in High-Andean forest ecosystems. These ecosystems are severely threatened, but little is known about their structure and functioning. We provide the first reports of the dasometric structure and spatial distribution of eight forests of Polylepis canoi, P. flavipila and P. rodolfovasquezii in the Central Peruvian Andes as fundamental information for management and conservation policies. We sampled all individuals ≥1 cm of diameter at ground level (DGL) in 20 plots of 10x10 m in each forest, and measured total height (TH) and DGL. Also, we mapped the spatial distribution of the individuals in two plots of 30x30 m (X and Y axes). We found differences in the dasometric structure between forests of the same species, which, in some cases, were associated with climate, soil or elevation variables. However, no well-defined pattern was found. The allometric relationships of the linear and non-linear models did not differ widely with respect to the R2 nor to the Akaike (AIC) scores, indicating that the forests did not show a saturation of tree height with increasing diameter. In the P. canoi forests, individuals with diameters ≥10 cm were the most abundant. In contrast, the forests of P. rodolfo-vasquezii showed a predominance of individuals with diameters ≤10 cm, whereas P. flavipila presented an altered structure with no relationship between DGL and TH in one of the evaluated forests. The analysis of spatial distribution according to the Ripley’s K function on a small scale revealed that P. flavipila and P. canoi presented random patterns, whereas P. rodolfo-vasquezii showed an aggregate pattern. Finally, our results showed that even forests of the same species have different dasometric structures, whereas spatial patterns differ only between species. So, caution must be taken when extrapolating information between species or forests during ecological studies and conservation actions.https://doi.org/10.25260/EA.19.29.3.0.812
Highlights
Polylepis (Rosaceae) is the dominant tree genus in High-Andean forest ecosystems above 3500 m a. s. l. from Venezuela to central Argentina (Zutta et al 2012; Zutta and Rundel 2017)
Polylepis subsericans and P. incana evidence a relationship between the location of forests associated with topographic features which varies in relation to elevation (e.g., Coblentz and Keating 2008; Toivonen et al 2018), whereas in other species such as Polylepis flavipila, P. reticulata, P. incana and P. australis the population structure and density have been characterized, demonstrating the importance of this information to know the current state of the forests and propose conservation actions (Camel and Castañeda 2018; Castro 2014; Cierjacks et al 2008; Pacheco 2015; Renison et al 2011)
Studies of Polylepis flavipila, P. racemosa and P. subsericans have shown that these species tend to have aggregate distributions associated with environmental variables such as humidity, soil depth and rock cover (Arizapana et al 2016b; Hurtado 2014)
Summary
We studied eight relicts of Polylepis forests in the central Peruvian Andes at elevations ranging from 3698 to 4352 m a. s. l. (Table 1, Figure 1). W) and Curimarca (11°33’49’’ S - 75°19’1’’ W) These forests presented on average the highest levels of annual mean precipitation (1474 mm/year) and annual mean temperature (7.3 °C). P. flavipila was evaluated at the Nor Yauyos-Cochas Landscape Reserve in the district of Laraos (12°19’38’’ S - 75°46’48’’ W), where there are low levels of annual mean precipitation (598 mm/year) and annual mean temperature (5.9 °C). The area is characterized by abundant grassland with shrubby plants such as Escallonia, Baccharis and Senecio (Trinidad and Cano 2016). These forests are affected by the presence of roads, livestock, extraction of firewood and the hemiparasite Tristerix chodatianus (Camel et al 2019)
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