Do consumer‐mediated negative effects on plant establishment outweigh the positive effects of a nurse plant?

Abstract

Many studies demonstrated the importance of facilitative effect by nurse plant on seedling establishment. Few studies evaluated the negative effects of consumers on plant establishment under nurse plants by dealing with them during multiple demographic processes. We investigated the balance between the facilitative effect and negative effects of consumers during multiple demographic processes in Malawi in southeastern Africa. We chose Ficus natalensis as a nurse plant and compared it with three other microsites in tropical woodlands: Brachystegia floribunda (a dominant woodland species), Uapaca kirkiana (a woodland species), and a treeless site. We quantified the seed rain, postdispersal seed predation, germination, and seedling survival of Syzygium guineense ssp. afromontanum (a common forest species). Within each microsite, we quantified the overall probability of recruitment. We also measured seedling abundance of S. guineense ssp. afromontanum. We found that Ficus natalensis exerted both positive and negative impacts on the establishment of S. guineense ssp. afromontanum. Ficus natalensis facilitated seed deposition, seed germination, and seedling survival. On the other hand, seed removal at postdispersal stage was highest under F. natalensis. Interestingly, B. floribunda also had positive effects on germination and seedling survival, but not on seed deposition. When we excluded the seed arrival stage from our estimation of the recruitment probability, the highest value was found under B. floribunda, not under F. natalensis. When we included the seed arrival stage, however, the order of recruitment probability between F. natalensis and B. floribunda was reversed. The probability was one order of magnitude higher under F. natalensis than under B. floribunda. Our estimation of the probability which included the seed arrival stage was consistent with natural patterns of S. guineense ssp. afromontanum establishment. Despite the presence of opposite effects, the net effects of F. natalensis on S. guineense ssp. afromontanum recruitment in tropical woodlands can be positive.

An exotic woody weed in a pastoral landscape provides habitat for many native species, but has no apparent threatened species conservation significance

“…), regardless of whether either the nurse or nursed is native or non‐native. Nurse plants, particularly unpalatable species, can increase seedling survival (Fujita & Yamashina ) by reducing browsing (Moser & Greet ) and abiotic stress (Navarro‐Cano et al . ).…”

“…Thorny shrubs have the potential to function as nurse plants (De Pietri 1992;Lugo 2004;Padilla & Pugnaire 2006;Tecco et al 2006), regardless of whether either the nurse or nursed is native or non-native. Nurse plants, particularly unpalatable species, can increase seedling survival (Fujita & Yamashina 2018) by reducing browsing (Moser & Greet 2018) and abiotic stress (Navarro-Cano et al 2018). The absences of any relationship between Gorse and both of seedling density and native species richness were inconsistent with the nurse plant hypothesis, perhaps because the native tree and shrub species are adapted to open woodland and require an open understorey to germinate and grow.…”

“…) or were absent. Exotic shrubs can allow rare plants to produce seed by protecting them against grazing (Gilfedder & Kirkpatrick ) and can act as nurse plants by protecting seedlings (Fujita & Yamashina ; Moser & Greet ).…”

“…Nevertheless, exotic plants do benefit native wildlife by providing food, materials or shelter in situations where the natives that once provided these resources have become infrequent or locally extinct (Mack et al 2000;Zavaleta et al 2001;D'Antonio 2002;Ewel 2004;Sogge et al 2008) or were absent. Exotic shrubs can allow rare plants to produce seed by protecting them against grazing ) and can act as nurse plants by protecting seedlings (Fujita & Yamashina 2018;Moser & Greet 2018).…”

Friends with benefits: The effects of vegetative shading on plant survival in a green roof environment

“…The lack of competition between some of the pairs of plants was unexpected as it has been well documented in other experiments that make use of nurse plants [49,50] and is ubiquitous in natural ecosystems. Some of the positive benefits of nurse plants are offset by the resource competition provided by adding another plant to the habitat [51].…”