Silvopastoral use of Nothofagus antarctica in Southern Patagonian forests, influence over net nitrogen soil mineralization

Abstract

In most temperate forest, nitrogen (N) is considered a limiting factor. This becomes important in extreme environments, as Nothofagus antarctica forests, where the antecedents are scarce. Thinning practices in N. antarctica forests for silvopastoral uses may modify the soil N dynamics. Therefore, the objective of this work was to evaluate the temporal variation of soil N in these ecosystems. The mineral extractable soil N, net nitrification and net N mineralization were evaluated under different crown cover and two site quality stands. The mineral N extractable (NH 4 ? -N ? NO 3 --N) was measured periodically. Net nitrification and net N mineralization were estimated through the technique of incubation of intact samples with tubes. The total mineral extractable N concentration varied between crown cover and dates, with no differences among site classes. The lowest and highest values were found in the minimal and intermediate crown cover, respectively. In the higher site quality stand, the annual net N mineralization was lower in the minimal crown cover reaching 11 kg N ha -1 year -1 , and higher in the maximal crown cover (54 kg N ha -1 year -1 ). In the lower site quality stand there was no differences among crown cover. The same pattern was found for net nitrification. Thinning practices for silvopastoral use of these forests, keeping intermediate crown cover values, did not affect both N mineralization and nitrification. However, the results suggest that total trees removal from the ecosystem may decrease N mineralization and nitrification.

Mistletoes and epiphytic lichens contribute to litter input in Nothofagus antarctica forests

“…In Nothofagus antarctica forests, thinning practices in silvopastoral systems modify the overstorey to increase understorey forage production by increasing available photosynthetic active radiation through reduction of tree density. Several studies have provided valuable information on changes in environmental parameters (e.g., solar radiation, temperature), tree physiological performance (e.g., photosynthetic response) and many other ecological processes (e.g., nutrient cycling) at the stand level (Peri, 2009;Bahamonde et al, 2012Bahamonde et al, , 2013. However, little is known about how canopy communities are affected by forest practices.…”

Soil quality indicators in an Andisol under different tree covers in disturbed Nothofagus forests

“…forest thinning practices for silvopasture (maintaining intermediate canopy cover values) did not affect either N-min or N-NO3. However, the lowest N-min and N-NO3 values were found in a treeless site, suggesting that the total removal of trees from the ecosystem can reduce N-min and N-NO3 (Bahamonde et al, 2013).…”

“…According to our results we could infer that the alteration of the forest by uncontrolled processes of logging or cattle grazing, and the tree cover modification can affect the quantity and quality of the substrates that enter in the soil, and N dynamics. The logging reduces the amount of trees and vegetation, and overgrazing can effect regeneration processes and soil structure (Bahamonde et al, 2013;.…”

Long-term monitoring of thinning for silvopastoral purposes in Nothofagus antarctica forests of Tierra del Fuego, Argentina

“…This methodology allowed to measured variation in these variables through the years, which greatly influenced on several ecological processes related to productivity in agroforestry systems (e.g. moisture availability, nutrient cycles, decomposition, regeneration) (Soler, 2012;Bahamonde et al, 2013Bahamonde et al, , 2015Martínez Pastur et al, 2013;Peri et al, 2016a). Finally, these monitoring also allowed us to detect changes in the control treatment (e.g.…”

“…To date, there is enough information to support most of the silvopastoral proposals, including forest component, natural cycles, regeneration, understorey and biodiversity (Lencinas et al, 2008(Lencinas et al, , 2015Quinteros et al, 2010;Gyenge et al, 2011;Ivancich et al, 2011Ivancich et al, , 2014Soler, 2012;Soler et al, 2013;Bahamonde et al, 2013Bahamonde et al, , 2015Martínez Pastur et al, 2013;Gargaglione et al, 2014;Echevarría et al, 2014;Gönc et al, 2015;Peri et al, 2016aPeri et al, ,b, 2017. However long-term results along the forest cycle, and its resilience deserve special attention.…”