Conservation of a Critically Endangered Endemic Halophyte of West Portugal: A Microcosm Assay to Assess the Potential of Soil Technology for Species Reintroduction

The soil system has been frequently overlooked during plant reintroduction planning and practice since working with soils and plant roots can be difficult, particularly in saline environments. Coastal saline environments are major contributors to regional and global biodiversity and an important source of endemic species. However, various species are in decline or considered threatened, particularly halophytes (salt tolerant) due to negative anthropic impacts. The Lusitanian endemic halophyte Limonium daveaui formerly had a large distribution range along the west coast of Portugal but currently it shows a restricted distribution in the Tagus estuary. Field surveys revealed that this critically endangered species forms few local populations with small size invaded by exotic species. In this study, we investigated the potential utilization of Technosols, an innovative sustainable, ecological engineering method combined with brackish water irrigation for potential L. daveaui reintroduction in native habitats. Seed germination percentages were evaluated in different environmental conditions. Through a microcosm assay, a Technosol was constructed using a saline Fluvisol with a mixture of low value inorganic and organic wastes, which were chemically characterized. Plants were cultivated in the Fluvisol and Technosol and irrigated with brackish water collected in the nearby area. To assess plant growth, morphometric parameters and the plants’ physiological status were assessed and the fresh and dry biomass determined. Results showed that seed germination was higher on moist filter paper with distilled water than in Fluvisol or Technosol. Plants grown in Technosol had a greater development, with higher values of photosynthetic indexes and biomass production than in Fluvisol. Our findings provide a basis for future in situ conservation studies and support the idea that eco-friendly soil technology approaches are beneficial to conserve rare halophyte species.

Minimizing Potential Allee Effects in Psittacine Reintroductions: An Example from Puerto Rico

The family Psittacidae is comprised of over 400 species, an ever-increasing number of which are considered threatened with extinction. In recent decades, conservation strategies for these species have increasingly employed reintroduction as a technique for reestablishing populations in previously extirpated areas. Because most Psittacines are highly social and flocking species, reintroduction efforts may face the numerical and methodological challenge of overcoming initial Allee effects during the critical establishment phase of the reintroduction. These Allee effects can result from failures to achieve adequate site fidelity, survival and flock cohesion of released individuals, thus jeopardizing the success of the reintroduction. Over the past 20 years, efforts to reestablish and augment populations of the critically endangered Puerto Rican parrot (Amazona vittata) have periodically faced the challenge of apparent Allee effects. These challenges have been mitigated via a novel release strategy designed to promote site fidelity, flock cohesion and rapid reproduction of released parrots. Efforts to date have resulted in not only the reestablishment of an additional wild population in Puerto Rico, but also the reestablishment of the species in the El Yunque National Forest following its extirpation there by the Category 5 hurricane Maria in 2017. This promising release strategy has potential applicability in reintroductions of other psittacines and highly social species in general.

Sphagnum reintroduction under a warming climate: keys to success

<p>Restoring peatland functioning is closely related to restoring growth of ecosystem engineering Sphagnum species. In strongly degenerated peatlands reintroducing diaspores of Sphagnum is necessary to overcome strong dispersal and establishment bottlenecks. Which reintroduction strategy varies between peatland types, surface properties and/or microclimate. Comparative analyses of restoration techniques is scarce, hampering informed management choices.    </p><p>We set out to assess keys to success for Sphagnum reintroduction on strongly humified bare peat in three degraded and long-time rewetted temperate peatlands in the Netherlands. To this end we experimentally manipulated water table position (control, extra water), type of abiotic shelter (control, nurse plants, mulch), Sphagnum species (S. magellanicum, S. papillosum and S. cuspidatum), species mixture (monoculture, mixed culture), diaspore size (clumped intact plants or fragments) and diaspore density (0, 36, 72, 156 plants/m<sup>2</sup>) and monitored Sphagnum survival, lateral expansion and environmental conditions. The experiment was established in 2018 and repeated in 2019, covering two of the most extreme summers in recorded history.</p><p>Water table close to the surface and shelter of a mulch layer were key to Sphagnum survival and growth irrespective of Sphagnum species, reintroduction method or year. Survival increased linearly with diaspore density. Diaspore size showed an interaction with mulch cover: fragments did best under mulch cover, whereas clumped plants survived better outside shelter.</p><p>Taken together our results suggest that successful reintroduction of Sphagnum is possible under a warming climate, but that strategies should be strongly focussed on amelioration of abiotic stress even when water tables are close to the surface. </p>