Forty years of lowland monsoon rainforest expansion in Kakadu National Park, Northern Australia

2006 ◽  
Vol 131 (4) ◽  
pp. 553-565 ◽  
Author(s):  
Daniel S. Banfai ◽  
David M.J.S. Bowman
1995 ◽  
Vol 43 (4) ◽  
pp. 367 ◽  
Author(s):  
IR Fordyce ◽  
GA Duff ◽  
D Eamus

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.


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

2010 ◽  
Vol 58 (4) ◽  
pp. 300 ◽  
Author(s):  
Jeremy Russell-Smith ◽  
Cameron P. Yates ◽  
Chris Brock ◽  
Vanessa C. Westcott

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.


2019 ◽  
Vol 11 (18) ◽  
pp. 2090
Author(s):  
Boyden ◽  
Wurm ◽  
Joyce ◽  
Boggs

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.


2007 ◽  
Vol 17 (5) ◽  
pp. 446-467 ◽  
Author(s):  
Anthea L. Mitchell ◽  
Richard M. Lucas ◽  
Brian E. Donnelly ◽  
Kirrilly Pfitzner ◽  
Anthony K. Milne ◽  
...  

2018 ◽  
Vol 69 (7) ◽  
pp. 1110 ◽  
Author(s):  
Tiffanie M. Nelson ◽  
Claire Streten ◽  
Karen S. Gibb ◽  
Anthony A. Chariton

Bacterial communities in floodplain and wetland soils cycle elements essential for flora and fauna. The coastal habitats of northern Australia are threatened with increasing saltwater intrusion (SWI) events that will destroy freshwater habitats. The effect of the impending SWI on bacterial communities is unknown. Here, we examined the bacterial communities of a tropical river floodplain located in World Heritage Kakadu National Park. Using 16S rRNA gene pyrosequencing, we measured the baseline bacterial communities from three morphologically distinct regions of the floodplain (lower, upper and backwater swamp), within three zones of the South Alligator River (upstream, cuspate and estuarine funnel or sinuous). Significant differences in the bacterial community were observed at each category of floodplain morphology and river zone. The greatest differences were due to pH and salinity. Large changes in bacterial compositions are predicted to occur with increases in salinity and pH. Saltwater intrusion is predicted to increase substantially in the next decades with sea-level rise, and is likely to cause large and significant changes to the bacterial community with unknown consequences for biogeochemical cycling. Kakadu National Park may benefit from incorporating bacteria into routine studies, because we have shown here that they are sensitive indicators of change, even across small ranges of abiotic variables.


1981 ◽  
Vol 8 (3) ◽  
pp. 207-215 ◽  
Author(s):  
J. E. Gardner ◽  
J. G. Nelson

At the very general level, the aim of this paper is to compare the interaction of national parks and native peoples in Northern Canada (Yukon Territory), Alaska, and the Northern Territory of Australia. Currently these areas are subject to increasing land-use pressures from mining, industrial development, the creation of national parks and related reserves, and native attempts to maintain traditional wildlife and renewable resource use. The study focuses on the interactions between national parks and native peoples on the premise that experiences can be compared and problems encountered in one area but possibly avoided in another.The study begins by briefly describing native land-use issues, land-rights arrangements, and organizations, in the Yukon Territory, central Alaska, and Northern Australia. The national park agencies are described, compared, and shown to differ considerably in institutional character, field of management, control of land, and external links with interest groups such as native peoples. Case-studies of the national parks etc. named Kluane (Yukon), Gates of the Arctic (Alaska), and Kakadu (Northern Territory of Australia), are presented to provide more details on similarities and differences in planning, types of tenure, native subsistence activities, and other factors.In the Yukon Territory, neither the national parks agency nor the native people are highly motivated to interact. In contrast, the park agencies and native people in Alaska and the Northern Territory of Australia recognize mutual benefits from interaction—largely as a result of legislation and policies which encourage cooperation. Native involvement officers now facilitate coordination in the Yukon and Alaska. Park agency native employment programmes are proceeding in all three ‘hinterlands’, while native people can own land on which national parks are established in Alaska and the Australian Northern Territory. Only in Australia are native people known to be directly involved in upperlevel national park management. Potential limitations on native subsistence and associated use of national parks range from moderate to severe, and are only defined clearly in Alaska. Lack of definition leads to confusion in deciding upon native use, while exceedingly precise definition precludes flexibility at the park level.A number of aids to a more mutually satisfactory interaction can be identified. One is motivation, or recognition by both parties that there are advantages to consultation and cooperation. Another, not yet achieved in the Yukon, is a land-claims settlement, stating the legislated rights of native peoples in the ‘hinterlands’ and giving them a land-holding and bargaining status which is comparable with that of government agencies. A third aid is comprehensive systematic and regional planning efforts involving opportunities for informed input from all affected parties. Such planning would provide a forum for consideration of a variety of interests, including national parks and native peoples. Finally, satisfactory interaction on the park site could be assisted by clear yet flexible means of deciding upon acceptable native use of parkland, the conservation of wildlife, and associated economic and cultural factors.


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