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Recruitment from seeds is among the most vulnerable stage for plants as global temperatures change. While germination is the means by which the vast majority of the world's flora regenerate naturally, a framework for accurately predicting which species are at greatest risk of germination failure during environmental perturbation is lacking. Taking a physiological approach, we assess how one family, the Cactaceae, may respond to global temperature change based on the thermal buffering capacity of the germination phenotype. We selected 55 cactus species from the Americas, all geo-referenced seed collections, reflecting the broad environmental envelope of the family across 70° of latitude and 3700 m of altitude. We then generated empirical data of the thermal germination response from which we estimated the minimum (T ), optimum (T ) and ceiling (T ) temperature for germination and the thermal time (θ ) for each species based on the linearity of germination rate with temperature. Species with the highest T and lowest T germinated fastest, and the interspecific sensitivity of the germination rate to temperature, as assessed through θ , varied tenfold. A left-skewed asymmetry in the germination rate with temperature was relatively common but the unimodal pattern typical of crop species failed for nearly half of the species due to insensitivity to temperature change at T . For 32 fully characterized species, seed thermal parameters correlated strongly with the mean temperature of the wettest quarter of the seed collection sites. By projecting the mean temperature of the wettest quarter under two climate change scenarios, we predict under the least conservative scenario (+3.7°C) that 25% of cactus species will have reduced germination performance, whilst the remainder will have an efficiency gain, by the end of the 21st century.

We argue that the need for a quality seed supply chain is a major bottleneck for the restoration of Chile's native ecosystems, thus supplementing the list of bottlenecks proposed by Bannister et al. in 2018. Specifically, there is a need for defining seed transfer zones, developing standards and capacities for properly collecting and storing seeds, reducing information gaps on seed physiology and longevity, and implementing an efficient seed supply chain with certification of seed origin and quality. Without such capacities, countries are unlikely to meet their restoration commitments. Although we focus on bottlenecks in Chile, the issues we raise are relevant to other countries and thus the global agenda for ecological restoration.

The seed storage behaviour of Fagus sylvatica and F. crenata was investigated. A large fraction of seeds of both species survived desiccation to about 3% moisture content (MC) (in equilibrium with 10% relative humidity at 20°C). Nevertheless, viability was reduced significantly and progressively by desiccation from 14% to 3% MC. In addition, during subsequent hermetic storage at constant temperatures of 20 to –20°C in F. sylvaticaand 10 to –20°C in F. crenata seeds, viability was lost more rapidly with reduction in MC below about 7.6–11.5% (40–71%relative humidity at 20°C). Thus, Fagus sylvatica and F. crenataexhibited intermediate seed storage behaviour. Survival at –20°C with 7.8–11.5% (F. sylvatica) and 7.6% MC (F. crenata) was comparatively good, with 64–84% of seeds remaining able to germinate normally after 2 years of hermetic storage, although this was neither appreciably better nor worse than at 0–10°C. Optimum seed storage environments, within the range investigated, were provided by combining temperatures of –10 to –20°C with 7.8–11.5% (F. sylvatica) or 7.6–9.5%(F. crenata) MC.

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The study evaluated the efficacy of organic-and hard-rock mine waste type materials on aided phytostabilization of Cu mine tailings under semiarid Mediterranean conditions in order to promote integrated waste management practices at local levels and to rehabilitate large-scale (from 300 to 3,000 ha) postoperative tailings storage facilities (TSFs). A field trial with 13 treatments was established on a TSF to test the efficacy of six waste-type locally available amendments (grape and olive residues, biosolids, goat manure, sediments from irrigation canals, and rubble from Cu-oxide lixiviation piles) during early phases of site rehabilitation. Results showed that, even though an interesting range of waste-type materials were tested, biosolids (100 t ha −1 dry weight, d.w.) and grape residues (200 t ha −1 d.w.), either alone or mixed, were the most suitable organic amendments when incorporated into tailings to a depth of 20 cm. Incorporation of both rubble from Cu-oxide lixiviation piles and goat manure into upper tailings also had effective results. All these treatments improved chemical and microbiological properties of tailings and lead to a significant increase in plant yield after three years from trial establishment. Longer-term evaluations are, however required to evaluate self sustainability of created systems without further incorporation of amendments.

Nurse effect and herbivory exclusion facilitate plant colonization in abandoned mine tailings storage facilities in north-central ChileEl efecto nodriza y la exclusión de herbivoría facilitan la colonización de plantas en depósitos de relaves mineros abandonados en Chile centro-norte JAIME RESUMENLas interacciones positivas, tales como el efecto nodriza, pueden atenuar el estrés ambiental (e.g., sequía) o reducir la intensidad de una perturbación (e.g., herbivoría), aumentando la probabilidad de regeneración de plantas en los ecosistemas naturales. El presente estudio analiza el potencial de uso de plantas nodriza para la restauración de ambientes artifi ciales, como los depósitos de relaves mineros abandonados. Evaluamos el reclutamiento y sobrevivencia de plántulas bajo y fuera del dosel de arbustos nodrizas, así como con y sin la exclusión de herbívoros, sobre un depósito de relaves de cobre abandonado en la zona centro-norte de Chile. Se utilizó como especie nodriza a Baccharis linearis (Asteraceae). Las plántulas evaluadas para reclutamiento fueron de B. linearis, Haplopappus parvifolius (Asteraceae), Schismus arabicus (Poaceae) y otros taxa de hierbas dicotiledóneas o gramíneas. El muestreo en terreno demostró que las plántulas de todas estas especies fueron más abundantes bajo el dosel de Baccharis que en las áreas abiertas entre arbustos. Solo para las plántulas de Baccharis estas diferencias fueron signifi cativas. A su vez, encontramos una reducción secuencial en la sobrevivencia de plántulas bajo las siguientes condiciones: bajo el dosel de Baccharis con exclusión de herbívoros, bajo el dosel sin exclusión, áreas abiertas con exclusión y, fi nalmente, en áreas abiertas sin exclusión de herbívoros. El sustrato bajo arbustos mostró mayor nivel de P y K a una profundidad < 10 cm en comparación con el sustrato de áreas abiertas. La compactación y el contenido de agua en el sustrato, así como la diversidad de plantas, no difi rieron entre ambientes. Nuestros resultados demuestran la importancia del efecto nodriza y la exclusión de herbívoros en el establecimiento de plántulas, en los depósitos de relaves mineros en la zona semi-árida del centro-norte de Chile. De este modo, arroja luz sobre las posibilidades de restauración ecológica en tales ambientes perturbados.Palabras clave: análisis de supervivencia, Baccharis linearis, desechos de rocas, Haplopappus parvifolius, sucesión primaria.