Dry Rainforest Research Articles

A pilot project testing the effectiveness of three weed control methods on the removal of Lantana camara in Forty Mile Scrub National Park, Queensland, Australia

SummaryLantana (Lantana camara) poses a serious threat to the biodiversity of the dry rainforest vegetation at Forty Mile Scrub National Park, Queensland, Australia, by outcompeting native species and increasing vulnerability to fire. This pilot study tests the effectiveness of three weed control methods (hand pulling, a glyphosphate‐based foliar spray herbicide and a picloram‐ and triclopyr‐based basal bark herbicide) in removing lantana and their success in reducing lantana fuel loads. The foliar spray herbicide was the most effective in killing lantana, while manual pulling resulted in the largest decrease in fuel height. We suggest that foliar spraying will be most efficient for combating large infestations of lantana, while hand pulling techniques are recommended for creating firebreaks or when minimizing damage to native species is paramount.

The Grose Vale flora and the value of documenting botanically interesting sites.

Particular botanical sites have always been attractive to botanists, and the recording of such sites even in an ad hoc way, adds to our long-term documentation of ecological change. Here we look at records from an unusual dry rainforest site in western Sydney, first recognised in 1910, and re-recorded on several occasions more recently. Though the site has little formal conservation protection, the records indicate that many of the original species still survive at the site, while the periodic recording draws attention to the scientific value of the site, particularly at a local level, and has increased its value as an ecological reference site. Much of the vegetation of the Cumberland Plain has been subject to major clearing and disturbance over the past 200 years, and almost all vegetation is recovering in some way. Repeated visits are valuable for getting a complete picture of the flora; repeated visits by the same botanist over the shorter term (e.g. within a few years) may also be valuable, especially as the revisiting botanist may be more likely to notice changes. By documenting sites now, and continuing this over future years; we can enhance the value of many existing sites.

Dry rainforests have a distinct and more diverse assemblage of epigaeic invertebrates than eucalypt woodlands: implications for ecosystem health monitoring.

Dry rainforests have a disproportionately higher diversity of plant species than the eucalypt woodlands that dominate Australian landscapes. While several endemic vertebrate species have been found in dry rainforests, their values for invertebrate fauna are relatively poorly known. Epigaeic invertebrates of four patches of dry rainforests in Queensland were annually compared to those of nearby eucalypt woodlands using pitfall traps between 1998 and 2002. Dry rainforests had significantly greater Order-level richness, lower dominance, fewer invertebrates and a different assemblage. Invertebrate composition was characterized by typically shelter- or moisture-requiring taxa, such as earwigs, pseudoscorpions, gastropods, millipedes, isopods, Diplura and Symphyla. This may reflect the greater prevalence of moister microhabitats in dry rainforests in comparison to woodlands. Coinciding with several years of low dry season rainfall, invertebrate abundance declined in dry rainforests but not woodlands, indicating that dry rainforest epigaeic fauna may be more sensitive to reduced soil moisture compared with woodland fauna. This may reflect differences of some taxa in evolutionary lineage or the mediation of vegetation phenology and differences in drought susceptibility of the two vegetation types. Importantly, the study provides evidence that faunal assemblages of drier rainforests may be more vulnerable to tipping points associated with droughts and changing rainfall regimes than nearby woodlands. Furthermore, it demonstrated the importance of including a range of vegetation types in any long-term monitoring programs and that an understanding of ecological responses to environmental drivers is critical to interpreting data. The relatively greater sensitivity of dry rainforest biota to droughts compared with woodlands indicates that it could provide a regional “control” for this effect.

Systematics and biology of the Australian seed bug genus Megadrymus Gross (Insecta:Heteroptera:Rhyparochromidae:Drymini)

Megadrymus Gross is an endemic seed bug genus that occurs in subtropical and tropical wet and dry rainforest on the eastern and northern coasts of Australia. The genus is revised with the redescription of the type species M. terraereginae Gross, the transfer of Brentiscerus tenuicornis (Gross) to Megadrymus, and the description of five new species: M. aurorae, sp. nov., M. brunneus, sp. nov., M. capeyorkensis, sp. nov., M. kakadu, sp. nov. and M. refugiensis, sp. nov. A key to species is included. A phylogeny, and biological and distributional information, are presented and discussed.

Land snails associated with limestone outcrops in northern Australia - a potential bioindicator group

Limestone outcrops and their associated monsoon vine thickets (dry rainforest) comprise a distinctive but poorly-known ecological community in northern Australia. Currently, most outcrops are poorly protected and lack adequate conservation management, the fire-sensitive rainforest vegetation is threatened by increased levels of landscape burning, and many outcrops are in need of restoration. Land snails obligatorily associated with this ecological community are particularly susceptible and have been identified as a potential bioindicator group for monitoring environmental health and for biodiversity conservation. These invertebrates are characterised by high levels of narrow-range endemism and beta-diversity. In the Tindall Limestone Formation at Katherine, NT, at least seven species of camaenid land snails have been recorded, of which five are endemic to the area. We describe a quantitative sampling protocol based on nocturnal counts to assess snail abundance in this formation at locations currently subjected to varying management regimes. Our preliminary observations indicate that snail assemblages in this area may be affected by an unbalanced grass-fire cycle driven by an increase in fire frequency and abundance of Sorghum macrospermum, an annual grass which is endemic to the Katherine region. At one site, for which snail abundance had been reported 30 years previously, it appears that this grass-fire cycle may have led to a dramatic loss of the understorey monsoon vine thicket habitat and the concomitant decline in abundance of a highly localised species of land snail. We conclude that the endemic land snails can be used as bioindicators for developing conservation management strategies of limestone-monsoon vine thicket associations, and recommend that this ecological community be better managed to minimise the incidence and intensity of fire.

The invasive weed Lantana camara increases fire risk in dry rainforest by altering fuel beds

Berry ZC, Wevill K & Curran TJ (2011). The invasive weed Lantana camara increases fire risk in dry rainforest by altering fuel beds. Weed Research51, 525–533.SummaryThe invasive weed, Lantana camara, dominates numerous tropical and sub‐tropical ecosystems and affects many aspects of ecosystem functioning, one of them being susceptibility to fire intrusion. The process by which L. camara might alter fire regimes in dry rainforest was examined by considering two potential mechanisms: (i) by being more ignitable than native species or (ii) by altering the structure and distribution of biomass to facilitate fire spread. We hypothesised that L. camara might alter fire regimes by both mechanisms. Measurements of leaf dry matter content, twig dry matter content and burn durations in laboratory trials implied that L. camara was less ignitable than native dry rainforest species. Fuel bed depths, leaf litter depths, percentage cover by fuels and amount of medium‐size class fuels were higher in dry rainforest invaded by L. camara than in non‐invaded forests. This suggests that the mechanism by which L. camara alters the fire regime in dry rainforest is by shifting the distribution of available fuels closer to the ground and providing a more continuous fuel layer in the understory. Management should focus on targeting L. camara removal around forest edges adjacent to frequently burned savannas and in areas of high conservation value.

The rare Australian epiphytic orchid Sarcochilus weinthalii associates with a single species of Ceratobasidium

Sarcochilus weinthalii is a rare, epiphytic orchid largely restricted to the dry rainforests of eastern Australia. Part of the conservation procedures for the orchid includes isolation and identification of the associated mycorrhizal fungus. In this study the mycorrhizal fungal partner of the species was determined through extraction and sequencing of DNA from both colonised orchid roots and pure fungal cultures grown out from orchid roots. A single species of Ceratobasidium predominated in the orchid suggesting that the orchid displays narrow fungal specificity. This mycorrhizal fungus can now be used in conservation procedures involving ex situ growth and the reintroduction of plants to the natural state.

Significant phorophyte (substrate) bias is not explained by fitness benefits in three epiphytic orchid species

Epiphytes rely on their phorophyte (host substrate) for support; epiphytic orchids also rely on mycorrhizal fungi for germination. Previous studies have proposed a degree of specificity in both interactions. Epiphytic orchids therefore provide an interesting system in which to examine multispecies interactions and the evolution of specialization. We examined the potential and actual distributions of three co-occurring, related epiphytic orchid species: Sarcochilus hillii, Plectorrhiza tridentata, and Sarcochilus parviflorus on phorophytes in Australia's temperate dry rainforests. These three small epiphytic orchid species were all biased toward certain woody plant species, in particular, the tree Backhousia myrtifolia, though the extent of specificity varied. Biases toward the most common phorophyte species were not explained by increases in adult orchid fitness, nor did probability of flowering increase on B. myrtifolia. Indeed, individuals on this woody phorophyte tended to have fewer inflorescences than those on other woody phorophytes. Only S. hillii benefited from establishment on B. myrtifolia; it had more leaves on this phorophyte than on others. In many cases what appear to be simple interactions between two species may be mediated by more complex symbioses. For this system, we propose that the cause for bias in orchid distribution occurs much earlier in an orchid's life and may be due to a bias of their mycorrhizal fungi for the dominant orchid phorophytes.

Atmospheric versus vegetation controls of Amazonian tropical rain forest evapotranspiration: Are the wet and seasonally dry rain forests any different?

This study analyzes evapotranspiration data for three wet and two seasonally dry rain forest sites in Amazonia. The main environmental (net radiation, vapor pressure deficit, and aerodynamic conductance) and vegetation (surface conductance) controls of evapotranspiration are also assessed. Our research supports earlier studies that demonstrate that evapotranspiration in the dry season is higher than that in the wet season and that surface net radiation is the main controller of evapotranspiration in wet equatorial sites. However, our analyses also indicate that there are different factors controlling the seasonality of evapotranspiration in wet equatorial rain forest sites and southern seasonally dry rain forests. While the seasonality of evapotranspiration in wet equatorial forests is driven solely by environmental factors, in seasonally dry forests, it is also biotically controlled with the surface conductance varying between seasons by a factor of approximately 2. The identification of these different drivers of evapotranspiration is a major step forward in our understanding of the water dynamics of tropical forests and has significant implications for the future development of vegetation‐atmosphere models and land use and conservation planning in the region.

Home range size in the blue-eyed black lemur ( Eulemur flavifrons): A comparison between dry and wet seasons

Western Madagascar is subjected to a long, dry winter season which coincides with food scarcity. We investigated the effect of this seasonal variation in food availability on the home ranges of blue-eyed black lemurs ( Eulemur flavifrons) in the Sahamalaza-Iles Radama National Park, north-western Madagascar. It was expected that home range would increase and overlap more in the dry season. The study was conducted in an area of dry rainforest from September 2006 to March 2008 with five lemur groups. Animals were located by direct observation and geographical locations recorded to determine the daily path length and the home range sizes of the study groups in the respective seasons. Daily path length and home range size varied significantly between seasons. Daily path length was significantly greater in the dry season (673.4 ± 539.2 m) than in the wet season (423.6 ± 183.2 m). Home ranges overlapped between groups in both seasons, but were significantly larger during the dry season (MCP: 7.5 ± 6.6 ha, 95% Kernel: 8.5 ± 6.6 ha) than in the wet season (MCP: 3.0 ± 1.6 ha, 95% Kernel: 4.1 ± 1.6 ha). There was no clear relationship between home range size and group size in either the dry or the wet season. Seasonal changes in home range area are likely to be a consequence of reduced food availability in the dry season. Compared to other primates, including some lemur species, the home range size of the blue-eyed black lemur is relatively small.

Rainforest remnants on headlands in the Manning Valley: Their composition and conservation significance

Remnant rainforest communities on headlands in the Manning Valley, northern coastal New South Wales are discussed. A preliminary list of native tree and shrub species from sties at Crowdy Head, Saltwater, Redhead and Black Head is provided and management problems are noted. The occurrence of a dry rainforest community at Black Head, containing Backhousia sciadophora, a species previously unrecorded from maritime sites, is discussed.

Distribution and population genetic structure of the critically endangered skink Nangura spinosa, and the implications for management

Many threatened species occur as small, isolated populations. Understanding the extent and genetic distinctiveness of these populations is essential for management. Nangura spinosa is a critically endangered skink known from two small populations in dry rainforest in south-east Queensland. We conducted targeted surveys between 2001 and 2010 at the two known N. spinosa sites (Nangur National Park, Oakview National Park area) and in 22 nearby forest blocks with potentially suitable habitat. N. spinosa was found only at the two previously known sites, which are ~36 km apart. The skink appears to be declining at Nangur NP, to an estimated extent of occurrence of 7.4 ha and potentially no more than 35 adults. In contrast, we increase the extent of occurrence at Oakview to 360 ha, where the population is at least in the hundreds. Sequencing of two mtDNA genes revealed considerable genetic divergence between the two populations (3.8% for ND4; 1.2% for 16S), suggesting an extended period of separation. Population fragmentation is therefore not the result of recent land clearing, but of long-term isolation by unsuitable habitat. Each population should be considered a distinct management unit. More data are required on population size and trends, recruitment and threats, particularly for the Nangur population.

A new limb-reduced skink (Scincidae: Lerista) from the dry rainforest of north Queensland, Australia

A new limb-reduced skink (Scincidae: Lerista) from the dry rainforest of north Queensland, Australia

A new limb-reduced skink (Scincidae: Lerista) from the dry rainforest of north Queensland, Australia

A new limb-reduced skink from the dry rainforest of north Queensland is described as Lerista rochfordensis sp. nov. It is distinguished from its congeners by forelimb absent with no groove or other indication, hindlimb 5–8% SVL with a single clawed digit, and five supraciliary scales. Its narrow distribution coupled with its apparent reliance on dry rainforest, an endangered habitat, meets the criteria outlined for a Vulnerable listing under the Environment Protection and Biodiversity Conservation Act 1999 (Qld).

Landscape‐scale detection and mapping of invasive African Olive (Olea europaea L. ssp. cuspidata Wall ex G. Don Ciferri) in SW Sydney, Australia using satellite remote sensing

AbstractQuestion: Is satellite imagery an effective tool for mapping and examining the distribution of the invasive species Olea europaea L. ssp. cuspidata at a regional landscape scale?Location: Southwest Sydney, Australia.Methods: Remote sensing software was used to classify pixels of Olea europaea L. ssp. cuspidata (African Olive) and major vegetation types from satellite imagery, using a “supervised classification” technique across a 721 km2 study area in the Cumberland Plain region of western Sydney. A map of African Olive distribution was produced from the image analysis and checked for accuracy at 337 random locations using ground observation and comparison with existing vegetation maps. The African Olive distribution data were then used in a GIS analysis with additional spatial datasets to investigate the relationship between the distribution of African Olive and environmental factors, and to quantify the conservation threat to endangered native vegetation.Results: A total area of 1907 ha of dense African Olive infestation was identified, with an omission error of 7.5% and a commission error of 5.4%. African Olive was found to occur on the steepest slopes (mean slope 14.3°) of the vegetation classes examined, with aspect analysis identifying a high prevalence on south‐ and southwest‐facing slopes. The analysis also quantified the level of African Olive infestation in endangered ecological communities, with Western Sydney Dry Rainforest (25% affected) and Moist Shale Woodland (28% affected) identified as most vulnerable to African Olive invasion.Conclusion: The distribution of African Olive can be efficiently mapped at a landscape scale. This technique, used in association with additional spatial datasets, identified African Olive as a significant environmental weed in SW Sydney, occupying a greater area than previously recognised and threatening several endangered native vegetation communities.

Are modern pollen data representative of west African vegetation?

Vegetation reconstructions are proposed in central Atlantic and north-west Africa from modern pollen data derived from an original data set of 452 samples and 1075 pollen taxa along a north-south transect from Congo to Egypt. We use multivariate statistical methods to link pollen samples to vegetation types, climate parameters (both annual and seasonal) and biomes. Analysis is based on a precise relationship between pollen assemblages and vegetation types and a re-assessment of Plant Functional Types and biomes at a sub-continental scale. The results show that the 13 main vegetation types described in western Africa are correctly defined by pollen data (both main pollen types and percentages) and both annual and seasonal climate parameters can be assigned to each of them. This includes distinction between the northern and southern types of dry rain forest from Cameroon and Congo and between tropical and non-tropical desert areas. Biomes are correctly reconstructed for all the vegetation types except for the tropical dry forest (TDFO) in the Sudanian vegetation zone (probably due to the strong anthropogenic disturbance of the natural landscape) and the tropical rain forest (TRFO) near the Equator (due to the highly complex biology of the rain forest, still poorly studied).

Water relations of woody plants on contrasting soils during drought: does edaphic compensation account for dry rainforest distribution?

The occurrence of dry rainforest in climates considered drier than the recognised limit for rainforest has been explained by the edaphic compensation hypothesis, which proposed that finer-textured soils facilitate the occurrence of rainforest at climatic extremes. We tested this by examining the effect of soil type on the water relations and plant traits of four dry rainforest species, during a severe drought and subsequent non-drought periods. We predicted plants growing in sandy soils would exhibit higher levels of water stress (lower predawn water potential and stomatal conductance) and possess morphological and physiological traits that more typically reflect drought resistance (late leaf fall in deciduous species, low specific leaf area, vertical leaf angles and stomata that close at low water potential) than those growing in loam soils. During drought, levels of water stress were similar across soil types, while post-drought plants on sandy soils were less stressed. Soil type did not cause shifts in drought tolerance traits, suggesting there has been no ecotypic differentiation of dry rainforest species across soil types for these traits. Hence, we found no support for the edaphic compensation hypothesis in adult plants; future studies should consider other life-cycle stages, such as seedlings.

Spatial pattern of dry rainforest colonizing unburnt Eucalyptus savanna

Spatial pattern of dry rainforest colonizing unburnt Eucalyptus savanna

Australia's Mammal Extinctions: A 50 000 year History

Tim Flannery?s The Future Eaters holistic ecological history invigorated Australians and took ccoiohry to the dinner table and into the pub. It was a monumental achievement. The problem with The Future Eaters for many Australian ecologists was that despite the wonderful prose and apparently beautiful logic of the simple story many of the details did not seem to add up or were presented rhetorically. At the time of reading, I had just finished a survey of the dry rainforests along the eastern seaboard and there were many fcatures of these ecologically tantalizing environments that were incompatible with them as the ?relic? environments central to Flannery?s story (Fensham 1995). The contribution of The Future Eaters as a provocateur of debate was immense, but it had ultimate shortcomings because Flannery could not afford the forensic scrutiny required, in a book that was packaged as a popular best seller.

Use of sicklepod, Senna obtusifolia (L.) Irwin and Barneby, as mulch interplant in cayenne pepper, Capsicum frutescens L., production

The suitability of sicklepod as mulch interplant to smother weeds in the crop interrows and generate mulch in situ in the production of cayenne pepper was investigated on the field in 1997 and 1998 at Ibadan in the dry rainforest of Nigeria. The Senna-interplant treatment was compared with plastic-, grass- and woodchip-mulched treatments, hand weeding control and unweeded control in a randomised complete block design using four replications. Pepper fruit yield from Senna-interplant was similar to those from plastic and grass mulch in 1997, but was significantly (P<0.05) lower in 1998. Uncontrolled weed growth reduced fruit yield by 73% and 78% in 1997 and 1998, respectively, compared to the mean fruit yield from all mulched treatments. Senna-interplant, plastic, grass and woodchip mulch treatments increased the fruit yield by 21%, 36%, 45%, and 11%, respectively, compared to the hand weeding unmulched treatment. Over the two years, the weed control efficiency of the Senna-interplant, plastic, grass and woodchip mulch, and hand weeding treatments relative to unweeded control treatment were 54%, 97%, 27%, 64%, and 88%, respectively. The afternoon temperature of the soil was reduced by the straw mulch types but increased by the plastic mulch. Soil moisture loss was less under all mulch types than in hand weeding and unweeded control treatments. The predominant weeds of the experimental area were Chromolaena odorata (L.) R.M. King & Robinson, Talinum fruticosum (L.) Juss, Synedrella nodiflora Gaertn and Laportea aestuans (L.) ex Miq with relative importance values 9.8%, 8.6%, 8.3%, and 6.3%, respectively. The weed dry weight, topsoil temperature and moisture depletion negatively correlated with the performance of the pepper plants.