Trait‐based selection of nurse plants to restore ecosystem functions in mine tailings

Abstract

Metal mining in drylands generates waste tailings with high toxicity, physical instability, as well as water and thermal stresses that hamper their biological colonization. This limits the restoration of ecosystem functions that are essential to re‐integrate these artificial micro‐deserts within the landscape matrix. We assessed the functional role of local nurse plant species and their traits to restore ecosystem functions related to soil fertility, soil microbial productivity and the reduction of abiotic stress. We sampled 30 metalliferous tailings in a mining district from semi‐arid Spain to detect nurse plant species and quantify their ability to promote essential functions from their establishment on the barren substrate up to the adult stage. We found 11 plant species acting as nurses out of 102 species able to colonize barren soils. Ten nurses further triggered a cascade of effects increasing soil fertility and microbial productivity and/or lowering soil abiotic stress. Plant species with larger life‐forms and longer periods of establishment since tailing abandonment contributed the most to the promotion of ecosystem functions. C4 plant species developing root systems with lower intensivity and depth:laterality ratios, as well as leaves with lower carbon:nitrogen ratios (C:N) induced a faster recovery of ecosystem functions. Synthesis and applications. We propose a protocol for selecting key species to be used in restoration programmes based on their ability to restore ecosystem functions under extremely stressful conditions. We encourage combination of multiple target species with complementary traits in order to reinforce the rehabilitation of ecosystem functions.

Using plant functional distances to select species for restoration of mining sites

“…Indeed, we have previously shown that some of the five nurse species used in this experiment have morphological and physiological traits that not only facilitate the establishment of other plants, but also induce a faster recovery of soil fertility, rates of organic matter decomposition and nutrient cycling or resistance to erosion (Navarro-Cano et al, 2018). This opens up the possibility to restore not only species populations and ecological interactions, but also relevant ecosystem functions (Navarro-Cano, Goberna, Valiente-Banuet, & Verdú, 2016).…”

“…Functionally diverse neighbourhoods provide elevated rates of ecosystem processes related to primary productivity, soil fertility, nutrient cycling, resistance to invasion or recruitment of new plant species (Dı́az & Cabido ; Funk, Cleland, Suding, & Zavaleta, ; HilleRisLambers, Adler, Harpole, Levine, & Mayfield, ). Indeed, we have previously shown that some of the five nurse species used in this experiment have morphological and physiological traits that not only facilitate the establishment of other plants, but also induce a faster recovery of soil fertility, rates of organic matter decomposition and nutrient cycling or resistance to erosion (Navarro‐Cano et al, ). This opens up the possibility to restore not only species populations and ecological interactions, but also relevant ecosystem functions (Navarro‐Cano, Goberna, Valiente‐Banuet, & Verdú, ).…”

“…We performed a seed sowing experiment beneath natural patches from five of the studied nurse species present on a mine tailing and their adjacent gaps (Navarro‐Cano et al, ). UTM coordinates of the tailing are 30S 690898E, 4164216N.…”

Facilitation and herbivory during restoration of California coastal sage scrub

“…While trait‐based restoration approaches are often used to select species for restoration, primarily focusing on traits associated with resource use, competition, and effects on ecosystem processes (Funk et al ; Kimball et al ; Ostertag et al ), selecting anti‐herbivory traits (unpalatable secondary compounds, protective structures, etc.) may have a greater impact on increasing the success of native establishment in CSS (Reader ; Gómez‐Aparicio et al ; Navarro‐Cano et al ). Planting unpalatable species around palatable ones may also deter herbivory of target species that are being restored (Callaway et al ; Smit et al ).…”

Impacts of competition and herbivory on native plants in a community‐engaged, adaptively managed restoration experiment

“…In coastal sage scrub, non-native grasses also experience herbivory, and herbivores may help to reduce the competitive effects of nonnatives (DeSimone & Zedler, 2001;Wainwright, Wolkovich, & Cleland, 2012). In Mediterranean-climate systems, adult shrubs may act as "nurse plants" by creating moist microsites that increase germination and early growth of native shrub seedlings (Cuevas, Silva, Leon-Lobos, & Ginocchio, 2013;Navarro-Cano, Verdu, & Goberna, 2018;Padilla & Pugnaire, 2006). Alternatively, adult shrubs may compete with seedlings for limited water, decreasing seedling survival (Marquez & Allen, 1996;Noumi, Chaieb, Michalet, & Touzard, 2015).…”