How does light and phosphorus fertilisation affect the growth and ectomycorrhizal community of two contrasting dipterocarp species?

Abstract

Phosphorus concentrations in many south-east Asian tropical rain forest soils are very low. To determine the growth responses of seedlings of a light-demanding (Shorea leprosula) and a more shade-tolerant (Hopea nervosa) dipterocarp species to increasing P, we carried out a nursery fertilisation experiment. Responses of symbiotic ectomycorrhizal (EcM) fungi to the treatments were also determined. Seedlings were grown under high light (13 mol m À2 d À1 ) or moderate light (4 mol m À2 d À1 ) in shade-chambers and were fertilised with a solution containing 0, 1, 10 or 100 mg L À1 P. The growth of Hopea and Shorea showed different responses to the light and P fertilisation treatments with Hopea having greater growth under moderate light conditions and Shorea having greater growth under high light conditions. Shorea responded to P fertilisation by increasing its foliar P concentrations and growth rates, whereas Hopea did not take up additional P and did not improve its growth rates. There was no effect of either light or P fertilisation on total EcM colonisation or EcM diversity, but around half of the EcM morphotypes observed were affected by one of these two abiotic perturbations, most notably for Riessiella sp. which increased with P fertilisation suggesting it may not be a mutualistic fungus. These results show how niche partitioning in both dipterocarp seedlings and EcM fungi can be divided along contrasting axes.

Limited response to nursery-stage mycorrhiza inoculation of Shorea seedlings planted in rubber agroforest in Jambi, Indonesia

“…The limited response of survival and growth to inoculation and the abundance of EcM of different morphotypes in all locations where S. lamellata and S. selanica were outplanted was unexpected and different from what has been reported for early growth of dipterocarp species from Borneo (Smits 1994;Turjaman et al 2007;Brearley et al 2007). Our results challenge, at least for lowland Sumatra, the concept that lack of EcM is a primary constraint on the use of dipterocarps for enrichment planting.…”

“…Seedlings of both species grew better in the open areas, such as ExForest_1 and ExRAF_1. Previous studies have shown growth of dipterocarp seedlings (mainly Shorea) to be enhanced in well illuminated conditions (Tennakoon et al 2005;Brearley et al 2007) and to show a positive correlation with gap distance (Otsamo 2000).…”

Foliar chemistry and standing folivory of early and late-successional species in a Bornean rainforest

“…In Borneo, many soils are N-and P-limited (Nomura and Kikuzawa 2003;Paoli et al 2005;Paoli 2006); e.g., typically, soil (NH 4 OAc/HOAc)-extractable concentrations are <1 Pg P g -1 (Brearley et al 2007). In nutrient-limited tropical ecosystems, plant defences against leaf herbivores can be adaptations to avoid the loss of nutrients.…”

The effect of nutrient supply and light intensity on tannins and mycorrhizal colonisation in Dutch heathland ecosystems

“…In non-ericaceous plants, shading usually reduces the levels of carbon-based secondary chemicals (Hartley et al 1997;Henriksson et al 2003, Ruohomäki et al 1996Iason et al 1996). In plants with ectomycorrhizal fungal symbionts, shade effects on the amount of colonisation or amounts of structures are ranging from no effect (Brearly et al 2007;Dehlin et al 2004) to decreased colonisation rates (Becker 1983;Ingleby et al 1998) or even increased colonisation rates (Prajadinata and Santoso 1993;Be'reau et al 2000). As these ectomycorrhizal fungi produce a Hartig net around the roots, we assume that they show a different response to shading compared to ericoid mycorrhizal fungi, which only proliferate within the epidermal cells of roots.…”