Elevational trends of tree fine root traits in species‐rich tropical Andean forests

Abstract

With increasing elevation, trees in tropical montane forests have to invest larger fractions of their resources into their fine roots in order to compensate for increasingly unfavorable soil conditions. It is unclear how elevation and related edaphic changes influence the variability in tree fine root traits and belowground functional diversity. We measured six fine root traits related to resource acquisition on absorptive fine roots of 288 trees from 145 species along an elevational gradient from 1000 m to 3000 m a.s.l. in tropical montane forests of the Ecuadorian Andes. We analyzed trait relationships with elevation and soil nutrient availability, and tested whether root functional diversity varied along these gradients. Fine roots at higher elevations and at more nutrient‐poor sites were thicker, had higher tissue densities, and lower specific root length and nutrient concentrations than at lower elevations. These trends were diluted by the coexistence of tree species with a broad range of different root traits within communities particularly towards lower elevations, where root functional diversity was significantly higher. We conclude that nutrient limitation and potentially further adverse conditions at higher elevations are strong environmental filters that lead to trait convergence towards a conservative resource use strategy, whereas different trait syndromes are equally successful at lower elevations.

Special Issue: Root traits and functioning: from individual plants to ecosystems

“…In this Special Issue, root trait patterns within plant communities (Table 1) reiterate what is observed within and across species, namely, that plants can display a wide variety of root trait strategies to carry out their belowground functions. Pierick and collaborators (2023) study the variation in root traits in tropical montane forests along an altitudinal gradient in the Andes. In their case, although there were weak trends towards more conservative root trait syndromes on high altitudes with deteriorating soil conditions, all tropical forest communities showed high within‐community variance in root traits at each altitude, confirming the importance of multiple strategies for resource capture in tropical forests.…”

Variations and patterns of C and N stoichiometry in the first five root branch orders across 218 woody plant species

“…2e), which may to some extent support the temperature–biogeochemistry hypothesis (Reich & Oleksyn, 2004). Similar results are found in tropical montane forests (Pierick et al ., 2023) and subtropical forests (He et al ., 2016). A previous study has suggested that root diameter and tissue density generally increased, but specific root length and nutrient concentrations decreased with increasing altitude, implying that plants exhibit a conservative resource‐use strategy to adapt to the nutrient limitation at high‐altitude biome (Pierick et al ., 2023).…”

“…Similar results are found in tropical montane forests (Pierick et al ., 2023) and subtropical forests (He et al ., 2016). A previous study has suggested that root diameter and tissue density generally increased, but specific root length and nutrient concentrations decreased with increasing altitude, implying that plants exhibit a conservative resource‐use strategy to adapt to the nutrient limitation at high‐altitude biome (Pierick et al ., 2023). Thus, the contrasting patterns of root N concentrations between latitude and altitude may be attributed to the specific traits (e.g.…”

“…Thus, the contrasting patterns of root N concentrations between latitude and altitude may be attributed to the specific traits (e.g. root morphology and physiological activities) and complexity of species diversity (Wu et al ., 2016; Freschet et al ., 2017; Pierick et al ., 2023). To adapt to the complex and diverse micro‐habitats in the ecosystems, woody plants may form special and diverse ecological adaptation strategies, but additional evidence is needed.…”

Experimental warming altered plant functional traits and their coordination in a permafrost ecosystem

“…Permafrost, perennially frozen soil and sediment that remains below 0°C for two or more consecutive years, occupies c. 16% of the global land area (Zhang et al, 2008). Permafrost areas are experiencing more rapid climate warming than many other regions (double the global average rate; Biskaborn et al, 2019), which is driving profound changes in plant community composition (Post et al, 2009;Elmendorf et al, 2012) and altering biogeochemical cycles (Schuur et al, 2022). Given that plants may respond to environmental change by adjusting their growth strategies and altering associations among functional traits (Violle et al, 2007;Reich, 2014), exploring change in plant functional traits provide a critical insight into understanding the linkage between ecosystem functions and environmental change (Lavorel & Garnier, 2012;Reichstein et al, 2014).…”