Endozoochory of a dry‐fruited tree aids quarry passive restoration and seed soaking further increases seedling emergence

Abstract

As practitioners promote passive restoration as a complementary approach to technical reclamation, it is imperative to know its drivers. Although the consequences of endozoochory can be crucial to passive restoration success, few experimental studies assess the use of heavily disturbed sites by seed dispersers such as carnivores and how the seeds they bring in emerge and survive. Using an indoor sowing experiment conducted in a quarry located within a natural park in Portugal, we examined for the first time how carnivore endozoochorous seeds collected in the quarry potentially influence its passive restoration, through effects on plant emergence and survival. Also, we tested whether sowing date and water soaking, relevant factors when sowings are to be carried out, would affect seedling emergence and mortality rates when compared with the effect of endozoochory. Our target species were included in the revegetation plan of the quarry, of which endozoochorous seeds of Carob tree (Ceratonia siliqua) were collected in sufficient number for analysis. Irrespective of the carnivore species, endozoochorous carob seeds performed similarly to untreated seeds regarding emergence rates. Endozoochorous carob seedlings showed greater mortality rates but the net result for the plant can still be the colonization of recently vacant habitats by a large proportion of viable seeds. Concerning sowing date, the later carob seeds were sown over the fruit-ripening season the faster seedlings emerged. Water soaking increased emergence rate by 6.5 times. Broadly, sowings with previous soaking and carnivore-mediated seed dispersal of this dry-fruited tree can jointly enhance quarry restoration. Implications for Practice• Restorers can undertake pilot sowing experiments prior to large-scale revegetation campaigns to identify which species benefit the most from endozoochory. • Carnivores in the surroundings of a quarry contribute a large proportion of viable seeds, likely assisting quarry passive restoration. • Carnivores ingesting carob seeds later in the fruiting season may assist quarry passive revegetation more readily as seeds ingested around that time emerge earlier. • Immersion in tap water is a simple, inexpensive, and highly efficient method to break physical dormancy when carob seed sowings are to be carried out in degraded sites.

Carnivores cross irrigation canals more often through overpasses than through culverts

“…Many wildlife species tend to avoid disturbances associated with roads such as moving vehicles, noise, and light (D'Amico et al, 2015;Denneboom et al, 2021). Although the carnivore species with the most crossings in our work are not particularly intolerant to human presence (Salgueiro et al, 2020), locations farthest from the paved roads are expected to still be areas where they forage and disperse the most across canals throughout their territory, increasing the likelihood of canal encounters and crossings. In the particular case of overpasses on irrigation canals, these generally connect unpaved roads used mainly by agricultural vehicles, implying little disturbance for these animals (Gačić et al, 2013).…”

“…Importantly, vast irrigation systems can lead to overlooked yet marked land use changes (Gačić et al, and Petrovan 2019;Martinig and Mclaren, 2019). Among the animal groups, carnivore mammals, given their large home-ranges and dispersal needs (Salgueiro et al, 2020), have been well-suited to assess the effect of the different crossing structures at the landscape level (Clevenger et al, 2001).…”

Enhancing biodiversity and ecosystem services in quarry restoration – challenges, strategies, and practice

“…Not only plants, but also animal species may thrive in such degraded habitats. Rohrer et al (), Salgueiro et al (), and Martin‐Collado et al () studied the habitat preferences of two cliff‐nesting bird species—the Sand Martin ( Riparia riparia ) and the Black Redstart ( Phoenicurus ochruros )—and a semiaquatic mammal—the Eurasian otter ( Lutra lutra ). In the first two studies, both authors found that the species were attracted to mined areas especially when unsuitable conditions prevailed in surrounding matrix habitats.…”

Bottom-up cascading effects of quarry revegetation deplete bird-mediated seed dispersal services

“…Therefore, there is an urging need to employ effective restoration practices in post-extraction areas to accelerate ecosystem recovery (Salgueiro et al, 2020a). Traditionally, restoration practices largely relied on soil formation and revegetation, however, awareness on the restoration of ecological processes and the services they provide is currently increasing (e.g., Dmitrakova et al, 2018;Salgueiro et al, 2020b).…”

“…Many plants often rely on seed dispersal services provided by frugivorous animals to colonise new areas (Herrera, 2002). Consequently, seed dispersal mediated by animals (i.e., zoochory) can contribute to further assist ecosystem restoration by promoting revegetation of vacant unrestored areas (Salgueiro et al, 2020b), if suitable conditions for their establishment are granted.…”