Abstract
Nutrient resorption is crucial for mineral element conservation and efficiency of forest species, but knowledge on its significance and the mechanisms involved is still limited for most species and habitats. Focusing on the harsh conditions for plant growth and survival of southern Patagonia, a field study for comparing the rate of foliar resorption of macro-, micro-nutrients, and trace elements in coexisting Nothofagus pumilio and Nothofagus antarctica forests was performed. Forests located in three contrasting productivity sites (with different soil and climatic conditions) were selected, and mature, functional versus senescent leaves of both species were collected at two different dates of the growing season. Macro- (N, P, Ca, K, S, and Mg), micronutrients (B, Cu, Fe, Mn, Zn, and Ni), and trace elements (Al, Li, Pb, Rb, Sr, Ti, and Tl) were determined in foliar tissues. The mineral element concentrations of mature and senescent leaves were used for calculating the nutrient resorption efficiency (NuR). In general, and making an average of all sites and species, macro-nutrient resorption showed a decreasing trend for N > S = K > P > Mg, being Ca the only macro-nutrient with negative values (i.e., no resorption). Resorption of the majority of the elements did not vary between species in any of the evaluated sites. Variation across sites in nutrient resorption efficiency for most macronutrients, some micronutrients, and trace elements was observed for N. antarctica, whereas N. pumilio had a similar NuR for all experimental sites. On the other hand, regardless of the site or the species, some elements were not resorbed (e.g., B, Cu, Fe, Mn, Al, and Ti). It is concluded that both Nothofagus species performed similarly concerning their nutrient conservation strategy, when coexisting in the same mixed forest. However, no evidence was gained for an increased rate of foliar NuR in association with the sites subjected to more limiting soil and climatic conditions for plant growth.
Highlights
Net primary productivity in temperate forests is strongly related to internal nutrient cycling (Schlesinger, 1991)
In light of the state of knowledge of nutrient resorption efficiency (NuR) of South-American Nothofagus species, the aim of this study was to compare the rate of foliar macronutrient, micronutrient, and trace element resorption in coexisting N. pumilio and N. antarctica forests located in contrasting productivity sites of southern Patagonia
The specific leaf area (SLA) was assessed for mature and senescent leaves of both Nothofagus species and values were within a similar range
Summary
Net primary productivity in temperate forests is strongly related to internal nutrient cycling (Schlesinger, 1991). The “movement” of nutrients from leaves prior to abscission toward other tissues and/or storage organs has been indicated as a key component of nutrient conservation in forests of the whole world (Ares and Gleason, 2007; Freschet et al, 2010), being the term “nutrient resorption” (NuR) widely accepted nowadays (Killingbeck, 1996). This strategy allows plants to use the resorbed nutrients for new growth and/or storage in vegetative tissues for further growth during the seasons (Van Heerwaarden et al, 2003), minimizing their dependence on the available soil nutrient pool. For example, a strong influence of latitude, mean annual precipitation, and temperature on N and P resorption (Yuan and Chen 2009; Zhao et al, 2017)
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