Flowering phenology of myrtaceous trees and their relation to climatic, environmental and disturbance variables in northern New South Wales

Abstract

Patterns of flowering phenology, which represent a partial description of food availability for nectarivores, are described for 20 species of myrtaceous trees on the mid‐north coast of New South Wales (NSW), Australia. Data were recorded monthly between 1982 and 1992 across 23 sites that comprise a variety of local environmental conditions and disturbance histories. Flowering periodicity and intensity were highly variable between species and sites, ranging from annual flowering to no flowering over the 10‐year period. Cool temperatures prior to floral budding was a strong predictor of flowering for nine species. Extraordinary climatic events also influenced flowering. The period of greatest flowering for all species combined occurred 9 months after the highest monthly rainfall recorded in the survey (March 1985). An 18‐month extreme drought led to poor flowering in Corymbia variegata, Eucalyptus acmenoides, Eucalyptus grandis and Eucalyptus resinifera, but recovery after the drought broke was rapid. In contrast to climate, few site‐based environmental variables explained the intersite variation in flowering performance of the tree species. Site disturbance from logging at two sites during the survey did not influence flowering in the remaining canopy over following years. No species showed a negative correlation with a history of recent logging, and direct comparisons, between large‐ and medium‐sized trees, of the percentage of foliage in flower showed no differences for any species. At the scale of a timber production forest, the negligible effect of tree size (if >10 cm diameter at breast height over bark), and high stem density resulting from selective logging, leave about half of the net harvestable area producing flowers at a similar density to unlogged forest. However, larger trees flowered more frequently than medium‐sized trees in C. variegata (medium: every 5.9 years; large: every 2.3 years) and there was a trend in this direction for 13 of 17 species. Low‐intensity burns and wildfires caused differing amounts of crown scorch, sometimes resulting in bud loss, but most species flowered at prefire levels 1–3 years after the disturbance. Eucalyptus microcorys and Angophora costata flowered poorly at sites that experienced frequent low‐intensity burns. Regionally, blossom shortages occur through a combination of spatial and temporal patchiness in flowering and the clearing of those species that occurred on soils preferred for agriculture. On the north coast of NSW, these shortages commonly occur from late winter to spring. Species that flower reliably in this period include Eucalyptus robusta, Eucalyptus tereticornis and Eucalyptus siderophloia in late winter and E. siderophloia and E. acmenoides in spring.

Reproduction and nutritional stress are risk factors for Hendra virus infection in little red flying foxes ( Pteropus scapulatus )

“…Eby -2007, may drive HeV spillover events. Finally, nectar and fruit availability are dependent on climatic conditions (Law et al 2000), and thus flying foxes-particularly the highly nectardependent LRFF-may be greatly affected by climate change. Our data suggest that such environmental stresses lead directly to changes in henipavirus infection and excretion dynamics.…”

Genetic control of flowering in spotted gum, Corymbia citriodora subsp. variegata and C. maculata

“…Our observations of translocated trees representing this region in the Bonalbo trial indicated that they took 20-21 months to develop, which was notably longer than the translocated CCV from the northern subtropical zone, but appeared to be in accord with the duration between initiation and anthesis for more southerly native populations of CCV (i.e. 15-24 months; Law et al 2000). Similar congruence in the key floral-development phases was evident for translocated and native CM (Table 2).…”

“…The November census time was chosen to commence monitoring because this was before the previously recorded anthesis period for spotted gums in northern NSW (Law et al 2000; Table 2). …”

“…However, most surveys have been of native stands (Dale and Hawkins 1983;Pook 1984;Pook et al 1997;Law et al 2000); thus, genetic differences are confounded with environmental factors. Observations of floral development in a common garden study are required to separate the degree of genetic and environmental determination in these processes.…”

Reproductive ecology of Syzygium alternifolium (Myrtaceae), an endemic and endangered tropical tree species in the southern Eastern Ghats of India

“…Sanewski (2010) observed that S. luehmannii flowered massively in the first spell and showed minor flowering in the second spell after unseasonal heavy rainfall in spring in southeast Queensland, Australia and attributed such a flowering response to the prevailing temperature and water availability (Sanewski 2010). Law et al (2000) reported that high rainfall in summer-autumn period resulted in heavy flowering in spring for most of the Myrtaceae members. Keatley et al (2002) reported a significant relationship between temperature and rainfall and flowering in eucalypts over 23 years.…”