Seed and microsite limitation inRheum nobile, a rare and endemic plant from the subnival zone of Sino-Himalaya

Abstract

Background: Species persistence, particularly in monocarpic species, depends on the successful recruitment of individuals. An understanding of the factors that limit the recruitment of rare monocarpic plant species is therefore vital for their conservation. Aims: To identify the factors limiting the recruitment of Rheum nobile, a rare and highly specialised monocarpic giant herb endemic to the high eastern Himalayas. Methods: Seed sowing (seeds added or not added) and seedling transplanting experiments were conducted in disturbed (vegetation removed) and undisturbed plots in the vicinity of established populations of R. nobile to explore the mechanisms of recruitment limitation. Four levels of photosynthetically active radiation (0, 15, 30 and 50 µmol m −2 s −1 ) and two sowing positions (beneath and above grass litter or moss layer) were manipulated in the laboratory to determine how ground cover limited seedling emergence. Results: Seed addition increased seedling recruitment. Disturbance significantly increased seedling emergence and establishment. Seed germination significantly decreased with the reduction of light availability, but 31.7% of all seeds germinated in complete darkness. Seedling emergence was close to zero when seeds were sown on top of a layer of grass litter or moss, but rose to 34.5% when the seeds were sown beneath such layers. Conclusions:Our results indicate that the recruitment of R. nobile is limited by a combination of seed and microsite availability. Therefore, in order to conserve this species, we suggest adding seeds to suitable sites and implementing soil disturbances in existing populations to create suitable microsites.

Recruitment of seedlings versus ramets as affected by pasture degradation in alpine meadows and the implications for ecological restoration

“…Seedling and ramet recruitment in meadow vegetation can be influenced by many factors, such as grazing or mowing (Edwards et al 2005;Bissels et al 2006), topography (Chauhan et al 2006;Mayer and Erschbamer 2011;Tokuoka et al 2011;Song et al 2013), soil nutrient status (Bisigato and Bertiller 2004;Iacona et al 2010) and weather (Batllori et al 2009). Reduction of vegetation cover due to overgrazing in alpine meadows has been found to increase seed rain of forbs species, which altered the balance of seedlings and ramets and led to further degeneration of the pasture (Shang et al 2008a(Shang et al , 2008b(Shang et al , 2013.…”

“…The availability of suitable microsites is crucial to seedling establishment in the alpine environment (Batllori et al 2009;Xu et al 2011;Song et al 2013). In the SD meadow, the high cover afforded by the tillering of Kobresia spp., together with Stipa aliena, imposes limitations on seedling establishment by all species.…”

Habitat‐specific responses of seed germination and seedling establishment to soil water condition in two Rheum species in the high Sino‐Himalayas

“…This is consistent with results presented by Necajeva and Levinsh (2008) and Engels et al (2011): the seeds of plants periodically exposed to a certain stress are more tolerant of the stress than those of plants less exposed to that stress. Consequently, the different abilities to tolerate flooding may explain, in part, why R. alexandrae is able to occur in wetland habitats, while R. nobile is not, since successful germination is the first requirement for plants to occupy a new site and develop a persistent population, especially species that rely entirely on seeds for regeneration (Ceccon et al 2006;Song et al 2013b). Unfortunately, we could not compare tolerance of seed germination to drought stress between R. alexandrae and R. nobile, since seed germination of R. alexandrae, like in R. nobile, was not inhibited by the applied drought stress (Fig.…”

“…S1a;Chen 1993), while R. nobile, the sympatric species, usually occurs on alpine scree and occasionally in the open patches of alpine meadow, i.e., in well-drained habitats ( Fig. S1b; Song et al 2013b). In this study, we aimed to examine how R. alexandrae and R. nobile respond to soil water conditions.…”

Uso del microhábitat por Encyclia pyriformis (Orchidaceae) en la Reserva Ecológica Los Pretiles, Cuba

“…Todo esto puede ser crítico para el mantenimiento de la diversidad (Gowland et al 2007). La disponibilidad de agua, luz, el rango de temperatura y el tipo de suelo son algunos de los factores que probablemente limiten la distribución de muchas especies (Guo et al 2011, Song et al 2013. En general, la preferencia del hábitat es asumida como adaptativa, y si las condiciones son buenas en estos sitios, se produce una selección natural que mantiene tales preferencias (Martin 1998).…”