Multi‐stemmed trees in montane rain forests: their frequency and demography in relation to elevation, soil nutrients and disturbance

Abstract

Summary 1.Multi-stemmed trees are a common component of tropical and temperate montane rain forests, where they co-occur with single-stemmed trees. We hypothesized that multi-stemmed architecture should predominate in less productive sites (such as at high elevation or with low soil nutrient availability) and that, because it frequently results from sprouting, it should prevail in sites that are frequently disturbed. We also hypothesized that where multi-stemmed architecture predominates, there should be lower rates of mortality and recruitment of individuals. 2. We tested these hypotheses using data from permanent plots in tropical montane rain forests in Jamaica (14 years) and in temperate montane rain forests in New Zealand (19 years). The frequency of multi-stemmed trees varied across plots in both forests (4 -34% in Jamaica; 0 -21% in New Zealand) along gradients of elevation and soil nutrients. 3. Analyses examined the direct and indirect effects of the various environmental variables that are likely to drive site productivity and disturbance. We showed contrasting predictors of the frequency of multi-stemmed trees in the tropical and temperate forests. Multi-stemmed trees in Jamaican forests were most frequent on sites of low soil nutrient status (especially available soil phosphorus, P) whereas in New Zealand they were most frequent at high elevation sites, especially towards tree line. In both forests there was no relationship between multi-stemmed tree frequency and slope. 4. Turnover (the mean of mortality and recruitment rates) of multi-stemmed trees in Jamaican forests was lowest on sites of low soil nutrient status (especially available P) but was unrelated to environmental predictors in New Zealand. In both forests, turnover rates of multi-stemmed trees overall were 60% lower than those for co-occurring single-stemmed trees, offering support for the hypothesis that multi-stemmed architecture favours persistence. 5. Synthesis . Our study demonstrates that multi-stemmed trees can predominate in low productivity sites in montane rain forests. Their low turnover compared with co-occurring single-stemmed trees confirms the importance of evaluating the persistence niche as a mechanism promoting woody species coexistence in forests.

Plant size and abiotic factors determine the intra-specific variation in the multi-stemmed architecture of Prunus lusitanica in the Northeast limit of its global distribution

“…Basal shoots are mainly triggered by some natural (broken and fallen trunks) or anthropogenic (logging) perturbations as occurs in several woody species (Kammesheidt, 1999;Nagaike et al, 1999). The sprouting ability by basal shoots reveals some potential of P. lusitanica to persist by self-regeneration despite some natural perturbations and human threats (Kammesheidt, 1999;Nagaike et al, 1999;Bond and Midgley, 2001;García and Zamora, 2003;Bellingham and Sparrow, 2009;Tanentzap et al, 2012). Canopy cover also affects the production of basal shoots.…”

“…The multi-stemmed architecture of woody plants arises from sprouting that is often interpreted as an induced response to disturbances (Bond and Van Wilgen, 1996;Peterson and Jones, 1997;Bellingham and Sparrow, 2009). Sprouting, in the form of basal and layering sprouts, in P. lusitanica is also promoted by several external (environmental and anthropogenic) factors but strongly influenced by the diameter (as a surrogate of plant size) of the largest trunk.…”

“…The possession of a sprout bank in poor light environments improves the chance of rapid vegetative reproduction when a gap occurs in the forest canopy (Hara, 1987;Peterson and Jones, 1997). In the long term, the sprouting ability of P. lusitanica by basal shoots might prolong the lifespan of clumps under stressful environments and after some perturbations (Del Tredici, 2001;Bellingham and Sparrow, 2009;Tanentzap et al, 2012) and may contribute to conserve the colonized habitat (Bond and Midgley, 2001;Kawecki, 2008).…”

“…Despite the relevance of sprouting in population and community dynamics Midgley, 2001, 2003;García and Zamora, 2003;Bellingham and Sparrow, 2009), little is known about the specific (either intrinsic or extrinsic) factors that trigger sprouting and the resulting multi-stemmed form in Iberian woody plant species. Most of the work has focused on common species and communities growing in Mediterranean environments affected by f ires (Vila and Terradas, 1995a,b;Paula and Ojeda, 2006).…”

“…Sprouting is a successful response against poor light environments (Peterson and Jones, 1997;Tanentzap et al, 2012) or a lack of nutrients (Bellingham and Sparrow, 2009) and is also a common response in plants after logging, f ire, herbivory or wind storms (Bellingham et al, 1994;Bond and Van Wilgen, 1996;Kammesheidt, 1999;Bond and Midgley, 2003). However disturbances are not always responsible for multi-stemmed architecture development.…”