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Final biomass (a) and survival (b) of Arenaria paludicola plants grown from cuttings in soils collected from five habitats representing a gradient of coastal influence (Salicornia) to freshwater influence (Salix). Salinity (ppt) varies
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Establishing new populations is essential for preventing the extinction of critically endangered plant species. However, defining the range of environmental conditions suitable for the most severely endangered species is challenging, since few wild populations remain for study. Experimental reintroductions of these species can achieve multiple cons...
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Context 1
... was a significant effect of soil collection zone on proportion survival in the greenhouse (v 4,44 2 = 9.49, p = 0.050); however, individual post-hoc compari- sons were not significant (Fig. 2b). Survival was reduced in the Salicornia soil, which has the most saline influence. There was no significant effect of soil collection zone on per plant aboveground biomass (F 4,26 = 0.55, p = 0.699; Fig. 2a). There was a significant difference in salinity between the soils collected in each zone, with Salicornia soil having the highest salinity (F 4,44 = 21.03, p \ 0.0001; Fig. 2c). Salinity in Salix and Oenanthe soils was negligible. There was a significant difference in percent soil saturation among the soils collected, with the soils with the most freshwater influence (Salix and Oenan- the) also being more saturated (Table 1). There was also a significant difference in pH among the soils collected in each zone, although pH did not vary linearly across the gradient of saltwater influence (Table ...
Context 2
... was a significant effect of soil collection zone on proportion survival in the greenhouse (v 4,44 2 = 9.49, p = 0.050); however, individual post-hoc compari- sons were not significant (Fig. 2b). Survival was reduced in the Salicornia soil, which has the most saline influence. There was no significant effect of soil collection zone on per plant aboveground biomass (F 4,26 = 0.55, p = 0.699; Fig. 2a). There was a significant difference in salinity between the soils collected in each zone, with Salicornia soil having the highest salinity (F 4,44 = 21.03, p \ 0.0001; Fig. 2c). Salinity in Salix and Oenanthe soils was negligible. There was a significant difference in percent soil saturation among the soils collected, with the soils with the most freshwater influence (Salix and Oenan- the) also being more saturated (Table 1). There was also a significant difference in pH among the soils collected in each zone, although pH did not vary linearly across the gradient of saltwater influence (Table ...
Context 3
... was a significant effect of soil collection zone on proportion survival in the greenhouse (v 4,44 2 = 9.49, p = 0.050); however, individual post-hoc compari- sons were not significant (Fig. 2b). Survival was reduced in the Salicornia soil, which has the most saline influence. There was no significant effect of soil collection zone on per plant aboveground biomass (F 4,26 = 0.55, p = 0.699; Fig. 2a). There was a significant difference in salinity between the soils collected in each zone, with Salicornia soil having the highest salinity (F 4,44 = 21.03, p \ 0.0001; Fig. 2c). Salinity in Salix and Oenanthe soils was negligible. There was a significant difference in percent soil saturation among the soils collected, with the soils with the most freshwater influence (Salix and Oenan- the) also being more saturated (Table 1). There was also a significant difference in pH among the soils collected in each zone, although pH did not vary linearly across the gradient of saltwater influence (Table ...
Context 4
... our greenhouse experiment, A. paludicola demon- strated an ability to tolerate a wider range of salinities than expected; although its survival was reduced in soils from the most saline areas (Fig. 2). The threshold trend we found is common in plants, displaying a non-linear decline in plant growth with salinity that includes a pronounced threshold effect ( Steppuhn et al. 2005). We were surprised by this result, because historic records of A. paludicola in freshwater sites led to the hypothesis that the species would be highly sensitive to soil salinity. However, other closely related species of Arenaria and Eremogone live in dry desert or disturbed habitats ( Baldwin et al. 2012) so mechanisms for osmotic regulation may be common in the group. Our results indicate that potential habitats for reintroduction of this species may not be restricted to the entirely freshwater habitat of the extant natural population. At our reintroduction sites, we saw dramatic differences in establishment success between habitat types. One year after outplanting, more than half of the transplants were alive in Oenanthe plots at both Baldwin Creek and Wilder Ranch; while no more than two individuals remained in any of the other plots (Fig. 4). This indicates that ecological characteristics varying on the scale of tens of meters are critical to establishment of our species. In the region of our study, Oenanthe sarmentosa seems to be an indicator of habitats where A. paludicola has the potential to thrive and it could provide a starting point when searching for other locations with reintroduction potential. However, O. sarmentosa has a broad range, and we do not mean to suggest that every patch of O. sarmentosa will be a suitable reintroduction site. The results of our experimental transplants reveal habitat requirements of A. paludicola that should be consid- ered along with indicator species occurrence to refine site selection in future transplants. We recommend using O. sarmentosa as a tool to identify candidate transplant locations within a site, but only in habitats with relatively open canopies. The efficacy of this site selection method was supported in a subsequent experiment at Golden Gate National Recreation Area in Marin County, where transplanted A. paludicola showed the greatest success in a habitat with a high abundance of O. sarmentosa and an open canopy ( Acierto et al. ...
Citations
... Moreover, monitoring is necessary for identifying unexpected threats that may reduce transplant survival. Interspecific competition, herbivory, climate stochasticity, alien species and human disturbance are examples of unexpected issues that may require mitigation in a translocation recipient site through aftercare (Bontrager et al. 2014;Daws and Koch 2015;Fenu et al. 2016). ...
... For example, fences were demonstrated to be a simple yet highly effective aftercare strategy to reduce the impact of herbivory and human disturbance in the translocated population of Dianthus morisianus (Fenu et al. 2016). In other studies, plant watering (Barrett et al. 2011) and the control of competing native and non-native species (Bontrager et al. 2014;Daws and Koch 2015;Commander et al. 2018) were shown to be particularly effective. Moreover, since some species require fire or physical disturbance to promote recruitment, prescribed burns have been demonstrated to positively affect the survival of translocated species i.e., Acacia attenuata (Dufourq and Shapcott 2019). ...
... Fire as a means to control competition was also site-specific, because it could be applied only in areas where it has an ecological role in shaping vegetation dynamics, like in fire-prone temperate and Mediterranean-type ecosystems (Dufourq and Shapcott 2019). It should be noted that the effects of post-planting management can vary, depending upon the context, so that in case of a rare species, there may not be an optimal, universal management regime for all habitats, as highlighted in some translocation studies (e.g., Bontrager et al. 2014). ...
Plant translocation can increase the chances of long-term survival of threatened plant species; nevertheless, can be costly and challenging, with unknowns in the pre- and post-release phases, limiting success. Methodological advances have been made in the pre-release phase but long-term monitoring and post-release site management (i.e., “aftercare”) are not always applied and almost neglected in the literature despite being frequently effective for identifying and mitigating unexpected threats (e.g., interspecific competition, herbivory) to outplant survival.
Aiming to fill this gap, we reviewed published and gray literature on 296 translocations to shed light on the importance of aftercare on translocation outcome. We identified the most common aftercare techniques, then we performed a meta-analysis on a subset of studies that were specifically designed to test the effect of aftercare against a control (i.e., no aftercare).
The most common aftercare techniques were competition reduction, water irrigation and plant protection. Aftercare significantly increased the percentage of survival of plants when herbivory reduction and other understorey species were enhanced. Aftercare reported also a positive trend toward improved qualitative outcome when plants were protected or competition was mitigated. Nevertheless, more evidence is needed on the importance and effectiveness of aftercare techniques.
Long-term monitoring and post-release site management should be the post-translocation standard in plant translocations when ethical and possible, with plant protection, competition limitation and water irrigation being applied when needed to reduce transplant mortality. To provide statistically supported data on the effect of aftercare on translocation outcome, aftercare should be tested against a control when feasible.
... Therefore, emphasis should also be given to the post-translocation phases, that include long-term monitoring of translocated plants and post-release site management, i.e. aftercare. These phases can positively impact post-translocation establishment and survival of plants (Bontrager et al. 2014;Daws and Koch 2015). In some extreme cases, continuous post-translocation management is the only way to maintain reintroduced populations (Adamski et al. 2020). ...
... Indeed, competition with natural vegetation, invasion of weeds, herbivory, below-average rainfall are just a few examples of unexpected threats that may affect translocation outcomes and need to be controlled through adaptive management of the out-planting site (e.g. through weeding, fencing and irrigation). Particularly, weed removal and native and/or invasive plant management have proved to effectively maintain the translocated population viable (Bontrager et al. 2014;Daws and Koch 2015;Tischew et al. 2017;Commander et al. 2018). ...
Plant translocations have been performed and are ongoing, aimed at establishing long-term resilient and self-sustaining populations. Nevertheless, some of them have not succeeded because of failure in pre- and post-translocation phases such as erroneous site selection and lack of long-term monitoring and adaptive management (i.e. aftercare). This study focused on the relative importance of site suitability and aftercare on the performance of reintroduced populations of Kosteletzkya pentacarpos. This species was studied in two sites representing opposite ends of its ecological niche (freshwater and brackish sites), in the presence of the local vegetation (Phragmites australis and Juncus sp. pl.) and in its absence. Data on environmental variables, plant growth, ecophysiology and reproductive performance were obtained. Kosteletzkya pentacarpos performed better in the brackish site, exhibiting higher performance especially in the presence of the local vegetation. Conversely, plants growing in the freshwater site had lower performance, despite the removal of the local vegetation. Environmental features of the sites affected species performance more than interactions with co-existing species and site management, highlighting that selection of suitable recipient site is crucial to ensure successful translocation. Aftercare is unlikely to effectively counteract the effect of sub-optimal ecological conditions in terms of plant establishment and performance.
... Determining suitable habitat for rare plant reintroductions often focuses on matching the ecological properties of recipient and reference sites based on similarities in community composition (Lawrence and Kaye, 2011;No€ el et al., 2011), indicator species (Bontrager et al., 2014;Ren et al., 2010), or habitat features (Maschinski and Wright, 2006). However, several challenges can arise when using these approaches to characterize the niche of a rare species and suitable locations for reintroduction. ...
... However, several challenges can arise when using these approaches to characterize the niche of a rare species and suitable locations for reintroduction. First, uncertainty in optimal habitat occurs when rare species are known from only a few locations that differ in vegetation structure and composition (e.g., Bontrager et al., 2014;Volis et al., 2011). Second, if rare plants exist today as remnant populations or demographic sinks, then current environmental conditions are suboptimal and can no longer support positive or stable population growth (Falk et al., 1996); for example, disturbance-dependent rare species can become confined to suboptimal habitat as disturbance regimes shift over time (Pavlovic, 1994). ...
Reintroductions of rare plants require detailed knowledge of habitat requirements, species interactions, and restoration techniques. Thus, incremental experimentation over many years may be required to develop adequate knowledge and techniques for successful reintroduction. To determine drivers of extinction in historical reintroductions of a federally endangered perennial (Astragalus bibullatus), we developed a reintroduction experiment to disentangle the relative importance of habitat quality, herbivores, and restoration technique on reintroduction success. In a factorial design, we manipulated access to vertebrate herbivores across different habitat types (mesic ecotone vs. xeric barren), and used founder populations comprised of more transplants and genetic sources than previous reintroduction attempts. In mesic ecotones where historical reintroductions failed, excluding herbivores, thinning woody encroachment to improve habitat quality, outplanting across a greater array of microhabitats, and increasing founder population size did not improve demographic rates over previous attempts. Compared to mesic ecotones, transplant survival rates and cumulative fruit production were more than two and ten times greater, respectively, in a xeric barren ecotone characterized by open, grassy, and dry microenvironmental conditions. Across all sites, herbivores decreased probabilities of survival and flowering of larger adult plants. Flowering rates were 80% greater inside relative to outside herbivore exclusion cages. Over a four-year period, only a single uncaged plant produced fruit. Our study demonstrates that habitat quality and vertebrate herbivory are key drivers of long-term persistence in rare plant reintroductions. Using incremental experiments that build on previous knowledge gained from long-term monitoring can improve reintroduction outcomes. © 2018 Kunming Institute of Botany, Chinese Academy of Sciences
... On the contrary, other reintroduction attempts failed after such drastic measures or on sites with bare soil after mining activities, because seedlings of the reintroduced species did not survive under such harsh conditions (Ballesteros et al., 2012;Drayton and Primack, 2000). Jurinea could possibly profit from a sparse vegetation cover (facilitation effects, Bontrager et al., 2014;Brooker et al., 2008), at least during the recruitment phase. This might be achieved by removing competitive grasses through topsoil removal or soil inversion before reintroducing typical dry grassland species together with Jurinea, e.g., by using sod cuttings from xeric sand dune grasslands. ...
... Constraints in establishing the first generation often result in important bottlenecks to population growth in rare plant species (Abeli and Dixon, 2016;Bontrager et al., 2014). A first major insight from our experiment is that Jurinea, a rare and overall declining xeric grassland species in Central Europe, can successfully establish a first generation of seedlingsbut only if drastic interventions prior to reintroducing seeds have created safe sites for germination. ...
... In contrast, soil inversion was the most successful treatment on both sites with an average of 477.0 and 141.4 rosettes in Gödnitz and Steckby, respectively, after seven years. The addition of other grassland species after soil inversion significantly hampered the population growth of Jurinea leading to 265.0 and 22.5 rosettes on average in Gödnitz and Steckby respectively emphasizing the importance of long-term studies on potential facilitation effects under different environmental settings (Bontrager et al., 2014;Buisson et al., 2008). Vegetative reproduction played an important role in the population buildup of the clonal growing species Jurinea and added at least twice as much as onsite generative reproduction to the final population size after seven years. ...
Reintroducing endangered plant species is an important conservation strategy. However, only a few studies evaluate their long-term reintroduction success. Because such information is vital for understanding the success and failure of species reintroductions, we conducted a seven-year reintroduction experiment with Jurinea cyanoides, an endangered xeric sandy grassland species. We tested Jurinea seed sowing combined with three treatments (mowing, top soil inversion, and top soil inversion with sod cuttings) on two sites with different nutrient status, applying a Latin-Square design. We compared germination, seedling survival and reproduction success between treatments and sites using GLMs and resampling methods. Reintroduction success in different
population stages varied across treatments, sites and over time, revealing the most successful treatment only after some years. Jurinea germinated in all plots, but almost no plants survived in control and mown plots. A first generation established successfully in both inversion treatments, but with fewer plants on the nutrient-poorer site. However, subsequent generative and vegetative reproduction was higher in this site than on the nutrientricher site. Between the two inversion treatments, that with only top soil inversion was more successful, since species introduced by sod cuttings hampered the population growth of Jurinea. We conclude that a radical elimination of competing species and removal of top soil is mandatory for a successful reintroduction of this rare species. The fact that site conditions that were most suitable for the first generation did not continue to facilitate population growth in the following years underlines the importance of long-term monitoring of reintroduction experiments.
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... The biogeography of species will provide important baseline information for plant protection and reintroduction (Bai et al., 2014;Bontrager et al., 2014). Meanwhile, a plant dispersion model is a helpful tool to gain insights into the species' biogeography (Lo et al., 2014). ...
A key step towards the restoration of heavily disturbed fragile coastal wetland ecosystems is determining the composition and characteristics of the plant communities involved. This study determined and characterized the community of higher plants in the Chenier wetland of Bohai Bay using a combination of field surveys, quadrat approaches, and multivariate statistical analyses. This community was then compared to other adjacent wetlands (Tianjin, Qinhuangdao, Laizhouwan, Jiaozhouwan, and Yellow River Delta wetland) located near the Huanghai and Bohai Seas using principal coordinate analysis (PCoA). Results showed a total of 56 higher plant species belonging to 52 genera from 20 families in Chenier wetland, the majority of which were dicotyledons. Single-species families were predominant, while larger families, including Gramineae, Compositae, Leguminosae, and Chenopodiaceae contained a higher number of species (each⩾6 species). Cosmopolitan species were also dominant with apparent intrazonality. Abundance (number of species) of temperate species was twice that of tropical taxa. Species number of perennial herbs, such as Gramineae and Compositae, was generally higher. Plant diversity in the Chenier wetland, based on the Shannon-Wiener index, was observed to be between the Qinhuangdao and Laizhouwan indices, while no significant difference was found in other wetlands using the Simpson index. Despite these slight differences in diversity, PCoA based on species abundance and composition of the wetland flora suggest that the Bohai Chenier community was highly similar to the coastal wetlands in Tianjin and Laizhouwan, further suggesting that these two wetlands could be important breeding grounds and resources for the restoration of the plant ecosystem in the Chenier wetland.
... There is a constantly growing number of studies showing that rare species can persist when placed into suitable habitat not only within (Bell et al. 2003;Kirchner et al. 2006;Maschinski and Duquesnel 2006;Aguraiuja 2011;Abeli et al. 2016;Fenu et al. 2016) but also outside of their known range (Jusaitis et al. 2004;Maschinski and Wright 2006;Van der Veken et al. 2007, 2012Colas et al. 2008;Wendelberger et al. 2008;Pico et al. 2009;Marsico and Hellmann 2009;Reckinger et al. 2010;Roncal et al. 2012;Maschinski et al. 2012;Bontrager et al. 2014;Munt et al. 2016). However, the long-term success of reintroductions and translocations in general is low (reviewed in Seddon et al. 2007;Godefroid et al. 2011;Dalrymple et al. 2011Dalrymple et al. , 2012, but see Guerrant 2012) and can be even lower considering publication bias towards successful reintroductions (Menges 2008;Miller et al. 2014). ...
Plant conservation biology needs a new paradigm to stop ongoing environmental degradation and species loss. This paper provides detailed methodological guidelines for the conceptual integration of conservation biology and restoration ecology through “conservation-oriented restoration” as introduced in a companion paper. Based on the latest theoretical developments in community ecology and vast experience gained by researchers in restoration ecology and conservation biology, this paper provides recommendations, among others, for (i) identification of a reference ecosystem; (ii) making operational species lists for introduction; (iii) choosing optimal restoration in terms of planting design, plant number and density; (iv) collecting, storing and using seeds; and (v) addressing plant–animal interactions.
... Establishing new populations in reintroduction projects proved to be a risky enterprise with a high chance of failure, and this led to recognition of the importance of replicating introduced populations over time and space (Guerrant 1996). In restoration, given high variability in seedling survival over even small spatial scales (G omez-Aparicio et al. 2005a;Garrido et al. 2007;Albrecht & McCue 2010;Bontrager et al. 2014;Inman-Narahari et al. 2014), trials conducted at multiple sites are becoming more and more popular (Butterfield 1996;Calvo-Alvarado et al. 2007;Wishnie et al. 2007;Zahawi and Holl 2009;Holl et al. 2011;Rom an-Dañobeytia et al. 2012;Alvarez-Aquino & Williams-Linera 2012;Encino-Ruiz et al. 2013;Martinez-Garza et al. 2013;Yang et al. 2013) and have started to include threatened species (Alvarez-Aquino et al. 2004;Avendaño-Y añez et al. 2016). ...
Plant conservation biology needs a new approach to cope with the rapid disappearance of species and ecosystems. This paper is an attempt to introduce such an approach via conceptual integration of conservation biology and restoration ecology in what can be called conservation-oriented restoration. Use of this term is limited to cases when restoration is applied to a still-functioning ecosystem, excluding cases when the destroyed ecosystem must be recreated or altered to a desirable state. The paper demonstrates the importance of habitat restoration for the majority of threatened species, and, although it may seem paradoxical, advocates usefulness of threatened plant species for restoration of natural habitats. It is proposed that threatened plant species should become an important part of many restoration projects and be introduced not only into locations where they currently grow or grew in the recent past, but also into suitable locations within their potential distribution range. Because the number of potentially suitable locations can be close to zero if we consider only untouched natural habitats as suitable, the introduction sites should include those that require restoration efforts. The available literature is reviewed to show why and how ecological restoration should become an integral part of the conservation biologist's armory.
... Establishing new populations in reintroduction projects proved to be a risky enterprise with a high chance of failure, and this led to recognition of the importance of replicating introduced populations over time and space (Guerrant 1996). In restoration, given high variability in seedling survival over even small spatial scales (G omez-Aparicio et al. 2005a;Garrido et al. 2007;Albrecht & McCue 2010;Bontrager et al. 2014;Inman-Narahari et al. 2014), trials conducted at multiple sites are becoming more and more popular (Butterfield 1996;Calvo-Alvarado et al. 2007;Wishnie et al. 2007;Zahawi and Holl 2009;Holl et al. 2011;Rom an-Dañobeytia et al. 2012;Alvarez-Aquino & Williams-Linera 2012;Encino-Ruiz et al. 2013;Martinez-Garza et al. 2013;Yang et al. 2013) and have started to include threatened species (Alvarez-Aquino et al. 2004;Avendaño-Y añez et al. 2016). ...
Plant conservation biology needs a new approach to cope with the rapid disappearance of species and ecosystems. This paper is an attempt to introduce such an approach via conceptual integration of conservation biology and restoration ecology in what can be called conservation-oriented restoration. Use of this term is limited to cases when restoration is applied to a still-functioning ecosystem, excluding cases when the destroyed ecosystem must be recreated or altered to a desirable state. The paper demonstrates the importance of habitat restoration for the majority of threatened species, and, although it may seem paradoxical, advocates usefulness of threatened plant species for restoration of natural habitats. It is proposed that threatened plant species should become an important part of many restoration projects and be introduced not only into locations where they currently grow or grew in the recent past, but also into suitable locations within their potential distribution range. Because the number of potentially suitable locations can be close to zero if we consider only untouched natural habitats as suitable, the introduction sites should include those that require restoration efforts. The available literature is reviewed to show why and how ecological restoration should become an integral part of the conservation biologist's armory.
... As changes to the environment are occurring, reintroduction of species to maintain or increase biodiversity may help species from becoming extinct (Bontrager et al., 2014). P. quinquefolius populations continue to decline from illegal harvesting (McGraw et al., 2010), deer browse (McGraw and Furedi, 2005), climate change (Souther and McGraw, 2011), and land-use change . ...
... Among the potential determinants of successful translocations which have not received much attention in conservation biology, it is critical to consider posttranslocation management activities, including the erection of fences and reduction in competition (i.e. Godefroid et al. 2011;Bontrager et al. 2014;Daws and Koch 2015). In particular, Godefroid et al. (2011) reported that management of the out-planting site through either preparation for planting (e.g. ...
... reduced competition) positively impacted the short-term establishment and survival of plant reintroductions and increased the probability of translocation success. Comparable results were also obtained in other studies (Bontrager et al. 2014;Daws and Koch 2015). However, as far as we know, this aspect as well as the economic Plant Ecol evaluation of this high-cost activity also remains unexamined. ...
... These aspects also highlight that the differences in the performance of protected and unprotected plants in the subsequent years were mostly linked to the management conditions. As already demonstrated (Godefroid et al. 2011;Bontrager et al. 2014), the management actions post-transplantation are thus very important, and their relevance in terms of plant outcome increases with time. ...
Plant translocation has become a widely used tool to improve the conservation status of threatened plants. Dianthus morisianus (Caryophyllaceae) is a narrow endemic plant which only grows on the Portixeddu coastal dune (South-West Sardinia). Its natural habitat has been strongly modified, and it is currently considered one of the most threatened plants of Sardinia. In a conservation effort, a translocation of reproductive plants was planned. Plants were obtained from seeds collected in the natural population and cultivated at the Botanic Gardens of Cagliari University. The following two suitable areas near the natural population were identified: the first is located in a fenced site which is managed by public administration, and the second is located in an unprotected site. In November 2010, 113 plants were reintroduced in site one, and in February 2011, 25 plants were reintroduced in site two; all plants were regularly monitored. The aim was to analyse the effect of different management activities (i.e. the herbivore and human exclusion) on transplanted plants. The following consistent differences between sites with different management types were found: the survival and growth of D. morisianus were enhanced by reducing herbivory and human disturbance; in particular, fences positively enhanced the plant’s long-term survival, reproductive success and seedling recruitment. This study highlights that management activities (i.e. erection of fences) should be incorporated into translocation design since they contribute to translocation success. Our experience can serve as a model for further translocations of the threatened plants of Sardinia and, more widely, of the Mediterranean islands.
