Temporal and structural effects of stands on litter production in Melaleuca quinquenervia dominated wetlands of south Florida

Abstract

Melaleuca quinquenervia dominates large areas of the Florida Everglades in the southeastern USA where it has transformed sedge-dominated marshes into melaleuca forests. Despite its prevalence, very little is known about the ecology and stand dynamics of this invasive tree. We delineated large-, intermediate-, and small-tree stands in non-flooded, seasonally flooded and permanently flooded areas of Florida in 1997, measured their biological attributes, and then quantified litterfall components for 3-4 year periods. Melaleuca wood components and mature seed-capsules comprised the largest and the smallest portions of aboveground biomass, respectively, while leaves, fine stems, mature fruits, bud scales, floral structures, and residues represented decreasingly smaller fractions of the litter during the succeeding year. Dry weight proportion of leaves in litter was greatest (80.9%) in non-flooded and least (69.1%) in permanently flooded habitats. It was also greatest in small (85.6%) and least in large (64.7%) tree stands. Reproductive structures and mature-fruit fractions in litter were highest in large-tree stands whereas the bud-scale fraction showed no relationship to tree size. Seasonally flooded habitats had the most litterfall, wherein small-, intermediate-, and large-tree stands generated 0.662, 0.882, and 1.128 kg m À2 yr À1 , respectively. Dry weight of stems, leaves, bud-scales, floral structures, and mature fruit fractions in litter increased as the predominant size of the trees in the stand increased. Total annual litter production was highest during 1999-2000. Leaf fall occurred year-round with maximal amount during April, July, and October. Highest amounts of bud scales and floral structures fell during October-January, which corresponded with flushes of vegetative growth and major flowering events. Overall, melaleuca alone accounted for nearly 99% of the total litterfall dry weight in all habitats and months sampled. The amount of non-melaleuca litter was greater in small-tree stands than in intermediate-or large-tree stands. Litterfall data of this nature will be helpful in detecting changes occurring in melaleuca canopies in response to biological control impact and in prescribing site-specific management strategies.

Attributes of Naturally Fallen (Rained) <i>Melaleuca quinquenervia</i> Seeds in Two Habitat Types of South Florida Wetlands

“…The hydrological attributes of these habitats are based primarily on the descriptions of Brown et al 1991) [14] and Kushlan 1991) [15]. Habitats designated as "occasionally inundated" may remain inundated (with less than 0.1 m depth) intermittently for a few hours to several days during or following periods of heavy rain but are neither continuously flooded nor flooded every year, while "permanently inundated" habitats remained inundated year-round [16] where water depth at the research site fluctuated from ca 0.3 -1.30 m during June of 1997. Soil types in these habitats are dominated by poorly drained organic muck deposited on limestone beds which are generally classified as Histosols [14].…”

“…Wooden boxes (0.5 × 0.5 m × 16-cm deep) were raised with legs to a height ranging from 20 -70 cm above ground level in occasionally inundated sites. Water levels in permanently flooded sites fluctuated from 0.3 to 1.3 m. Therefore, the wooden litter trap boxes were modified to float at least 10 cm above the water surface by mounting a capped 3.8-liter plastic jar under each of the four corners of the supporting frame and tying them loosely to a nearby tree to secure them in place [16]. This allowed seed traps mounted on two sides of the wooden boxes to float above the water lavel.…”

A study of the carbon stocks of Melaleuca forests in the coastal regions of Southern Vietnam and South East Queensland Australia

“…For instance, Rayamajhi et al (2006) Eucalyptus forests in Australia and while there is clearly a lack of precision in our estimate of carbon stocks due to the paucity of data available, we are confident that they provide an indicative estimate. In Tasmanian forest landscapes, the above-ground carbon density of dry forests, wet forests (eucalypt and non-eucalypt), wet eucalypt forests, mature eucalypt forests, mature dry eucalypt forests, and mature wet eucalypt forests was 118 tC/ha, 185 tC/ha, 222 tC/ha, 179 tC/ha, 121 tC/ha, and 232 tC/ha, respectively (Moroni et al, 2010).…”

“…The amount of Melaleuca forest litter fall have been found to be quite high; from 7.00 to 7.67 t/ha/year in Australia (Finlayson et al, 1993;Greenway, 1994); and from 8.30 to 8.91 t/ha/year in Florida, USA Rayamajhi et al, 2006) (Table 3.2). Compared with other USA wetland forests, the mass of Melaleuca litter fall was much higher than in Cypress swamps in…”

“…Congdon (1979), Finlayson et al (1993) and Greenway (1994) examined litter dynamics in Melaleuca forests in Australia, while Rayamajhi et al (2006) examined the litter dynamics in Melaleuca forests in Florida, USA. The rate of litter fall in Melaleuca forests in Australia has been estimated to be between 7.00 and 7.67 t/ha/yr in the floodplains of Northern Queensland (Finlayson et al, 1993) and South East Queensland (Greenway, 1994), respectively.…”