The Ecophysiology of Allosyncarpia ternata (Myrtaceae) in Northern Australia: Tree Physiognomy, Leaf Characteristics and Assimilation at Contrasting Sites

1995 ◽  
Vol 43 (4) ◽  
pp. 367 ◽  
Author(s):  
IR Fordyce ◽  
GA Duff ◽  
D Eamus
Keyword(s):  
National Park ◽  
Light Flux ◽  
Dry Weight ◽  
Chlorophyll B ◽  
Northern Australia ◽  
Apparent Quantum Yield ◽  
Leaf Characteristics ◽  
Open Forest ◽  
Open Woodland ◽  
Monsoon Rainforest

Allosyncarpia ternata S.T.Blake, a large, evergreen tree endemic to the northern part of the Northern Territory, Australia, dominates the canopy in a wide variety of habitats, including monsoon rainforest on ravine floors, open forest and woodland on cliffs, screes and sandsheets, and open woodland on ridges and hilltops. This study examines tree physiognomy, leaf characteristics and leaf assimilation rates of A. ternata growing at sites with strongly contrasting micro-climates near Baroalba Springs, Kakadu National Park. By comparison with trees growing on the ravine floor, cliff and hilltop trees are generally shorter, they branch lower, are more frequently multi stemmed and have higher ratios of canopy width to height, while their leaves are generally smaller and thicker and contain less chlorophyll a and chlorophyll b per unit dry weight. They have lower mean specific leaf areas and higher mean stomatal densities. Assimilation measurements on leaves at a cliff site showed significantly higher rates of light-saturated assimilation during the morning than in the afternoon. On the ravine floor, by contrast, assimilation responses to changes in light flux density did not vary significantly through the day. Leaves of trees growing on the ravine floor had lower values oi light-saturated assimilation and light compensation point, and higher values of apparent quantum yield than cliffside leaves.

scholarly journals Tree growth rates in north Australian savanna habitats: seasonal patterns and correlations with leaf attributes

2004 ◽  
Vol 52 (3) ◽  
pp. 303 ◽  
Author(s):  
L. D. Prior ◽  
D. Eamus ◽  
D. M. J. S. Bowman
Keyword(s):  
Growth Rates ◽  
Fire Regime ◽  
Leaf Mass Per Area ◽  
Northern Australia ◽  
Wet Season ◽  
Nitrogen And Phosphorus ◽  
Mature Trees ◽  
Open Forest ◽  
Eucalypt Woodland ◽  
Monsoon Rainforest

We demonstrate a significant relationship between leaf attributes and growth rates of mature trees under natural conditions in northern Australia, a pattern that has not been widely reported before in the literature. Increase in diameter at breast height (DBH) was measured every 3 months for 2 years for 21 tree species from four habitats near Darwin: Eucalyptus open forest, mixed eucalypt woodland, Melaleuca swamp and dry monsoon rainforest. Assimilation rates and foliar chlorophyll, nitrogen and phosphorus concentrations were positively correlated with growth rate and negatively correlated with leaf mass per area. For most species, increases in DBH were confined to the wet-season (summer) period between November and May. Average annual increases in DBH were larger in the dry monsoon rainforest (0.87 cm) and the Melaleuca swamp (0.65 cm) than in the woodland (0.20 cm) and the open forest (0.16 cm), and were larger in non-Myrtaceous species (0.53 cm) than in Myrtaceous species (0.25 cm). These results are discussed in relation to the frequent fire regime prevailing over much of northern Australia which causes the marked contrast between the small pockets of fire-tender closed monsoon rainforest and large expanses of fire-tolerant savanna.

Threats to monsoon rainforest habitat in northern Australia: The case of Ptychosperma bleeseri Burret (Arecaceae)

1993 ◽  
Vol 18 (4) ◽  
pp. 463-471 ◽  
Author(s):  
PIERS BARROW ◽  
GORDON DUFF ◽  
DAVE LIDDLE ◽  
JEREMY RUSSELL-SMITH
Keyword(s):  
Northern Australia ◽  
Monsoon Rainforest

Fire regimes and interval-sensitive vegetation in semiarid Gregory National Park, northern Australia

2010 ◽  
Vol 58 (4) ◽  
pp. 300 ◽  
Author(s):  
Jeremy Russell-Smith ◽  
Cameron P. Yates ◽  
Chris Brock ◽  
Vanessa C. Westcott
Keyword(s):  
National Park ◽  
Fire Regime ◽  
Woody Species ◽  
Fire Regimes ◽  
Stem Density ◽  
Northern Australia ◽  
Juvenile Period ◽  
Climate Conditions ◽  
Fine Fuels ◽  
Ecologically Sustainable

Few data are available concerning contemporary fire regimes and the responses of fire interval-sensitive vegetation types in semiarid woodland savanna landscapes of northern Australia. For a 10 300 km2 semiarid portion of Gregory National Park, in the present paper we describe (1) components of the contemporary fire regime for 1998–2008, on the basis of assessments derived from Landsat and MODIS imagery, (2) for the same period, the population dynamics, and characteristic fine-fuel loads associated with Acacia shirleyi Maiden (lancewood), an obligate seeder tree species occurring in dense monodominant stands, and (3) the fire responses of woody species, and fine-fuel dynamics, sampled in 41 plots comprising shrubby open-woodland over spinifex hummock grassland. While rain-year (July–June) rainfall was consistently reliable over the study period, annual fire extent fluctuated markedly, with an average of 29% being fire affected, mostly in the latter part of the year under relatively harsh fire-climate conditions. Collectively, such conditions facilitated short fire-return intervals, with 30% of the study area experiencing a repeat fire within 1 year, and 80% experiencing a repeat fire within 3 years. Fine fuels associated with the interior of lancewood thickets were characteristically small (<1 t ha–1). Fine fuels dominated by spinifex (Triodia spp.) were found to accumulate at rates equivalent to those observed under higher-rainfall conditions. Stand boundaries of A. shirleyi faired poorly under prevailing fire regimes over the study period; in 16 plots, juvenile density declined 62%, and adult stem density and basal area declined by 53% and 40%, respectively. Although the maturation (primary juvenile) period of A. shirleyi is incompletely known, assembled growth rate and phenology data indicated that it is typically >10 years. Of 133 woody species sampled, all trees (n = 26), with the exception of A. shirleyi, were resprouters, and 58% of all shrub species (n = 105) were obligate seeders, with observed primary juvenile periods <5 years. Assembled data generally supported observations made from other northern Australian studies concerning the responses of fire-sensitive woody taxa in rugged, sandstone-derived landscapes, and illustrated the enormous challenges facing ecologically sustainable fire management in such settings. Contemporary fire regimes of Gregory National Park are not ecologically sustainable.

scholarly journals Grouseberry (Vaccinium scoparium Leiberg ex Coville) fruit production in forest openings in Banff National Park, Alberta

2015 ◽  
Vol 128 (4) ◽  
pp. 400 ◽  
Author(s):  
Ian Pengelly ◽  
David Hamer
Keyword(s):  
National Park ◽  
Forest Canopy ◽  
Fruit Production ◽  
Fire Disturbance ◽  
Subalpine Forest ◽  
Prescribed Burns ◽  
Banff National Park ◽  
Open Forest ◽  
Understory Shrubs ◽  
Forest Openings

Grouseberry (Vaccinium scoparium Leiberg ex Coville) is an abundant dwarf shrub in the understory of many areas of subalpine forest in Banff National Park and has the potential to produce fruit important for wildlife. However, the suppression and prevention of wildfires, which began in the early 1900s in the park, have reduced fire-dependent shrubland and open forest and increased the extent of closed, mature forest. Because canopy closure is typically associated with decreased fruit production by understory shrubs, the decline in fire disturbance may be reducing Grouseberry fruit production. To quantify this effect, we measured Grouseberry fruit production under various forest canopies at 10 sites in Banff during 2004–2012. We measured site openness by modeling photosynthetically active direct solar radiation (dPAR) adjusted for overshadowing by topography and coniferous foliage. We found a positive relation between Grouseberry fruit production and dPAR in 2006 and 2010–2012, but not in 2008 or 2009, the 2 years of lowest fruit production; data were lacking for 2004, 2005, and 2007. We also recorded high Grouseberry fruit densities beginning 5 years after fire removed the forest canopy in four prescribed burns conducted during 2001: fruit production was 3.3 to more than 20 times that in adjacent mature forests in 5 of the 6 years analyzed. This study shows the potential ecological benefits of both prescribed burns and wildfire in upper subalpine forests where Grouseberry is widespread, but fruit production is low under the forest canopy.

scholarly journals Remote Sensing of Mangroves and Estuarine Communities in Central Queensland, Australia

2020 ◽  
Vol 12 (1) ◽  
pp. 197
Author(s):  
Debbie Chamberlain ◽  
Stuart Phinn ◽  
Hugh Possingham
Keyword(s):  
Remote Sensing ◽  
Time Series ◽  
Land Cover ◽  
Great Barrier Reef ◽  
National Park ◽  
Landsat 8 ◽  
Barrier Reef ◽  
Change Analysis ◽  
Estuarine Wetland ◽  
Open Forest

Great Barrier Reef catchments are under pressure from the effects of climate change, landscape modifications, and hydrology alterations. With the use of remote sensing datasets covering large areas, conventional methods of change detection can expose broad transitions, whereas workflows that excerpt data for time-series trends divulge more subtle transformations of land cover modification. Here, we combine both these approaches to investigate change and trends in a large estuarine region of Central Queensland, Australia, that encompasses a national park and is adjacent to the Great Barrier Reef World Heritage site. Nine information classes were compiled in a maximum likelihood post classification change analysis in 2004–2017. Mangroves decreased (1146 hectares), as was the case with estuarine wetland (1495 hectares), and saltmarsh grass (1546 hectares). The overall classification accuracies and Kappa coefficient for 2004, 2006, 2009, 2013, 2015, and 2017 land cover maps were 85%, 88%, 88%, 89%, 81%, and 92%, respectively. The cumulative area of open forest, estuarine wetland, and saltmarsh grass (1628 hectares) was converted to pasture in a thematic change analysis showing the “from–to” change. We generated linear regression relationships to examine trends in pixel values across the time series. Our findings from a trend analysis showed a decreasing trend (p value range = 0.001–0.099) in the vegetation extent of open forest, fringing mangroves, estuarine wetlands, saltmarsh grass, and grazing areas, but this was inconsistent across the study site. Similar to reports from tropical regions elsewhere, saltmarsh grass is poorly represented in the national park. A severe tropical cyclone preceding the capture of the 2017 Landsat 8 Operational Land Imager (OLI) image was likely the main driver for reduced areas of shoreline and stream vegetation. Our research contributes to the body of knowledge on coastal ecosystem dynamics to enable planning to achieve more effective conservation outcomes.

scholarly journals Spatial Dynamics of Invasive Para Grass on a Monsoonal Floodplain, Kakadu National Park, Northern Australia

2019 ◽  
Vol 11 (18) ◽  
pp. 2090
Author(s):  
Boyden ◽  
Wurm ◽  
Joyce ◽  
Boggs
Keyword(s):  
Satellite Imagery ◽  
Wild Rice ◽  
National Park ◽  
Fire History ◽  
Spatial Dynamics ◽  
Gradient Boosting ◽  
Native Vegetation ◽  
Northern Australia ◽  
Stochastic Gradient Boosting ◽  
The World

African para grass (Urochloa mutica) is an invasive weed that has become prevalent across many important freshwater wetlands of the world. In northern Australia, including the World Heritage landscape of Kakadu National Park (KNP), its dense cover can displace ecologically, genetically and culturally significant species, such as the Australian native rice (Oryza spp.). In regions under management for biodiversity conservation para grass is often beyond eradication. However, its targeted control is also necessary to manage and preserve site-specific wetland values. This requires an understanding of para grass spread-patterns and its potential impacts on valuable native vegetation. We apply a multi-scale approach to examine the spatial dynamics and impact of para grass cover across a 181 km2 floodplain of KNP. First, we measure the overall displacement of different native vegetation communities across the floodplain from 1986 to 2006. Using high spatial resolution satellite imagery in conjunction with historical aerial-photo mapping, we then measure finer-scale, inter-annual, changes between successive dry seasons from 1990 to 2010 (for a 48 km2 focus area); Para grass presence-absence maps from satellite imagery (2002 to 2010) were produced with an object-based machine-learning approach (stochastic gradient boosting). Changes, over time, in mapped para grass areas were then related to maps of depth-habitat and inter-annual fire histories. Para grass invasion and establishment patterns varied greatly in time and space. Wild rice communities were the most frequently invaded, but the establishment and persistence of para grass fluctuated greatly between years, even within previously invaded communities. However, these different patterns were also shown to vary with different depth-habitat and recent fire history. These dynamics have not been previously documented and this understanding presents opportunities for intensive para grass management in areas of high conservation value, such as those occupied by wild rice.

scholarly journals Hg Levels in Marine Porifera of Montecristo and Giglio Islands (Tuscan Archipelago, Italy)

2020 ◽  
Vol 10 (12) ◽  
pp. 4342
Author(s):  
Camilla Roveta ◽  
Daniela Pica ◽  
Barbara Calcinai ◽  
Federico Girolametti ◽  
Cristina Truzzi ◽  
...  
Keyword(s):  
National Park ◽  
Total Mercury ◽  
Additional Data ◽  
Dry Weight ◽  
Mercury Content ◽  
Mediterranean Species ◽  
Direct Mercury Analyzer ◽  
Mercury Analyzer ◽  
Main Input ◽  
First Time

Porifera are filter-feeding organisms known to bioaccumulate different contaminants in their tissues. The presence of mercury (Hg) has been reported in different Mediterranean species, mainly collected in the southern coast of France. In the present study, mercury concentrations in the tissue of the sponges of Montecristo and Giglio, two islands of Tuscany Archipelago National Park (TANP), are presented for the first time. Analyses of total mercury content were performed by Direct Mercury Analyzer. Statistical differences have been reported in the Hg concentrations of species collected in both islands, but they do not appear related to the anthropic impacts of the islands. Among the collected species, a high intra- and inter-variability have been recorded, with Cliona viridis showing the lowest concentration (0.0167–0.033 mg·kg−1 dry weight), and Chondrosia reniformis and Sarcotragus spinosulus the highest (0.57 ± 0.15 and 0.64 ± 0.01 mg·kg−1 dry weight, respectively). The variability of Hg measured did not allow us to identify sponges as bioindicators of toxic elements. Anyway, these results improve knowledge on the ecosystem of the TANP, underlining the species-specificity of metal concentrations for Porifera, and providing additional data to address the main input of the Marine Strategy guidelines to protect coasts, seas and oceans.

scholarly journals Selection Criteria for Drought-Tolerant Bread Wheat Genotypes at Seedling Stage

2019 ◽  
Vol 11 (9) ◽  
pp. 2584 ◽  
Author(s):  
Hafiz Ahmed ◽  
Muhammad Sajjad ◽  
Mingju Li ◽  
Muhammad Azmat ◽  
Muhammad Rizwan ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Selection Criteria ◽  
Dry Weight ◽  
Shoot Length ◽  
Seedling Stage ◽  
Chlorophyll B ◽  
Fresh Weight ◽  
Drought Tolerant ◽  
Selection For ◽  
Thermo Stability

Diminishing water resources as a result of excessive use of water for irrigation and climate change posture a severe global threat to food security. Herein, an experiment was conducted to determine the selection criteria for drought-tolerant bread wheat genotypes at the seedling stage using morphological and photosynthetic pigmentation-related traits. A panel of 105 wheat landraces, historical Pakistani varieties, and advance breeding lines were evaluated under normal and drought stress using factorial completely randomized design. The root length, fresh weight, dry weight, cell membrane thermo-stability, and chlorophyll b were positively correlated among themselves under both normal and stress conditions. Hence, selection of any one of these traits enhances the performance of other traits. The shoot length was non-significant and negatively associated with all other studied characters except relative water content. The results suggested that selection for shoot length could not improve genetic gain for drought tolerance. Out of 10 principal components (PCs), the first three PCs were showed significant genetic variation under both conditions. The first three PCs showed 74.6% and 76% cumulative genetic variation under normal and drought conditions, respectively. Based on PCA, 10 drought-tolerant and five drought-susceptible genotypes were identified. Overall results suggested that selection for root length, fresh weight, dry weight, cell membrane thermo-stability, and chlorophyll b at the seedling stage would improve genetic gain for drought tolerance. The outperforming genotypes under drought stress conditions can be useful in future wheat breeding programs, and early selection for the traits recommended in this study will be effective for developing high-yielding and drought-tolerant wheat varieties.

Sign in / Sign up

Export Citation Format

Share Document