Plant recovery techniques do not ensure biological soil‐crust recovery after gypsum quarrying: a call for active restoration

Abstract

Biological soil crusts (biocrusts) are a key component of dryland ecosystems worldwide. However, large extensions of biocrusts are disturbed by human activities, gypsum quarry being an outstanding example. Restoration techniques applied have offered satisfactory results for vascular plants but they could greatly differ in promoting biocrust recovery. A basic question remains unaddressed: can measures for plant recovery accelerate or promote the recovery of biological crusts? We have examined eight different situations: undisturbed natural habitat, five treatments with no restoration measures (overgrazed area, abandoned quarry, topsoil removal from natural habitat, and two areas filled with gypsum mining spoil), and 2 areas receiving restoration measures (manual sowing and hydroseeding). We took 40 soil cores to determine cover of lichen, moss, and cyanobacteria. Biocrust richness and cover were higher in the undisturbed habitat, with remarkable differences for the different components among treatments. Cyanobacteria were well represented in all the cores (restored and non‐restored). Mosses were promoted the most by hydroseeding. Lichen cover was remarkably higher in undisturbed samples, very low in the quarry abandoned in 1992, and 0 in the rest. Complete spontaneous recovery of biocrusts was inefficient in the 25‐year period examined. Plant restoration measures could speed up its recovery comparing with non‐restored areas. Cyanobacteria and mosses can spontaneously recover fairly well. However, promoting them would accelerate the appearance of lichen. For lichen, inoculation or translocation of lichen thalli might be proposed. Therefore, our results call for the inclusion of active restoration measures of biocrust components in recovery plans, especially for lichens.

Patterns in biocrust recovery over time in semiarid southeast Spain

“…The lichen crust, still to be recovered, shows and average net growth of around 0.7% per year in Lepraria and 1.7% per year in Squamarina and Diploschistes. Differences between types of crust agree with what was obtained in other works ( Belnap and Warren, 2002 ; Dojani et al, 2011 ; Gypser et al, 2015 ; Williams et al, 2018 , Lorite et al, 2020 , among others). The recovery of the microbial crust ensures a certain stabilization of the soil, which favors the establishment of lichens ( Belnap and Büdel, 2016 ; Deng et al, 2020 ), reduces erosion ( Chamizo et al, 2012a ) and reduces the risk of degradation of these areas ( Belnap, 1995 ; Cantón et al, 2021 ).…”

“…Several authors have found that the ability to colonize and the growth rate of microbial crust are greater than that of lichen or moss crust ( Belnap and Eldridge, 2001 ; Dojani et al, 2011 ; Lorite et al, 2020 ; among others). In fact, this could be perhaps the only certainty to date in relation to succession in biocrusts.…”

“…Due to the differences in development observed in the field and by other authors ( Belnap and Eldridge, 2001 ; Dojani et al, 2011 ; Lorite et al, 2020 ), we grouped the species cover from the inventories in two general biocrust-type covers present in all the communities analyzed: microbial crust, composed of light and dark crust, and lichen crust, composed of lichen and moss species. Mosses were not considered separately due to their much lower abundance.…”

Assisted dispersal and retention of lichen‐dominated biocrust material for arctic restoration

“…Interest in assisted biocrust establishment using single or multiple biocrust species has recently increased, often to restore ecological benefits (Pointing & Belnap 2012; Bu et al 2013; Zhao et al 2016; Antoninka et al 2018). No known research addresses propagation and dispersal of lichen biocrusts for restoration in arctic tundra, although studies assessed assisted dispersal of biocrusts in alpine environments (Letendre et al 2019), and lichens in other ecosystems (reviewed in Smith 2014) including reindeer husbandry (Roturier et al 2007; Roturier & Bergsten 2009), endangered species conservation (Lidén et al 2004), lichen biodiversity maintenance in managed forests (Sillett & McCune 1998; Hazell & Gustafsson 1999; Hilmo 2002), and restoration (Duncan 2011; Gypser et al 2015; Ballesteros et al 2017; Lorite et al 2020). Inoculation techniques commonly assessed in the growth chamber and field have included transplantation of whole crust pieces, sieving crust material to simulate natural vegetative fragmentation, dry or wet (in a slurry) dispersal, and spreading of individual species (Belnap 1993; Scarlett 1994; Roturier & Bergsten 2009; Stewart & Siciliano 2015).…”

Identifying social–ecological gaps to promote biocrust conservation actions

“…Some other studies have also evaluated the linkages and interactions between all these positive effects of biocrusts and the performance of other living natural resources (5 %) such as vascular plants (i.e. Luzuriaga et al, 2012;Rodriguez-Caballero et al, 2018b) or vertebrates (Eldridge et al, 2010;Fig. 2).…”