The prospect of biofuels as a transport alternative fuel in Australia is reviewed and discussed in this paper. The Australian transport sector is the second largest energy consuming sector which consumes about 24% of total energy consumption. A part of this energy demand can be met by ecofriendly biofuels. A wide array of different biofuels feedstocks including Australian native species, their distributions, oil content, traditional uses are reviewed and listed in the descending order of their oil content. The world biofuel scenario as well as the 20 largest biofuel production countries and their mandates on biofuels blending with petroleum diesel are presented. Australia’s biofuel production, consumption, production facilities and future investment projects are also reviewed and discussed. The study developed a biofuel supply chain for Australia and found that the second generation biofuels have better prospects as a future alternative transport fuel in Australia. These biofuel feedstocks are readily available and can overcome the shortcomings of the first generation biofuels, such as socio-economic, environmental and food versus land use challenges. Although some research is in progress, further study is needed on the process development of second generation biofuel production at commercial scale in Australia and abroad.

Prospect of biofuels as an alternative transport fuel in Australia.

Summary

1. The role of waterbirds as vectors of plants and invertebrates within and between arid-zone wetlands is poorly understood. We present the first detailed study of passive dispersal by nomadic birds in Australasia. We investigated the numbers and types of invertebrate and plant propagules within freshly collected faecal samples as well as their viability. We compared dispersal among Grey Teal (Anas gracilis), Eurasian Coot (Fulica atra) and Black Swan (Cygnus atratus) in the Macquarie Marshes, a complex of temporary to semi-permanent wetlands in New South Wales.



2. When faecal samples (n = 60) were inundated in the laboratory and monitored over 3 weeks, ciliates (75% of samples), nematodes (22%), ostracods (13%) and rotifers (5%) were recorded, with higher taxon richness in coot samples. Faecal samples (n = 71) were also sieved to quantify intact propagules, and ostracod eggs (70% of samples), large branchiopod eggs (31%) and bryozoan statoblasts (31%) were the most abundant invertebrates. Diaspores of 19 plant taxa were recorded, 14 of which were germinated in the laboratory or shown to be viable at the end of germination trials. The abundance and diversity of invertebrate propagules was highest in coot samples, whereas the abundance and diversity of diaspores was highest in teal samples.



3. One Australian Pelican (Pelecanus conspicillatus) sample was obtained and found to contain more taxa and far more propagules than any sample from other waterbirds, suggesting that piscivorous birds might have an important role in the indirect dispersal of propagules ingested by fish.



4. Our results support a role for birds in explaining the distributions of cosmopolitan plant genera such as Lemna, Typha, Myriophyllum and Nitella. The alien plants Ranunculus sceleratus, Medicago polymorpha and Polygonum arenastrum were recorded, demonstrating the potential role of waterfowl in the spread of exotic species. As the frequency and duration of flooding of arid-zone wetlands decreases owing to human activities, the importance of waterbirds in facilitating recolonisation of temporary wetlands is likely to increase.

The potential role of waterbirds in dispersing invertebrates and plants in arid Australia.

. Plants possessing generalized dispersal syndromes are likely to be more invasive than those relying on specialist dispersal agents. To address this issue on a local and regional scale, avian seed dispersal of the invasive alien Chinese tallow tree (Sapium sebiferum (L.) Roxb.) was assessed in forests and spoil areas of South Carolina and along forest edges in Louisiana during the 1997–99 fruiting seasons. Tallow trees in these floristically distinct habitats had a few common and many casual visitors, and considerable species overlap among habitats was found. However, bird species differed in the importance of dispersing and dropping seeds among habitats. Important dispersal agents common to forests and spoil areas of South Carolina included Northern Flicker, American Robin and Red-winged Blackbird, whereas Red-bellied Woodpecker and European Starling were important in the former and latter habitat, respectively. In Louisiana, Red-bellied Woodpecker, American Robin, Northern Cardinal and Eastern Bluebird dispersed many seeds. Nearly all species foraging on seeds were winter residents. Estimated numbers of seeds dispersed and dropped were higher in spoil areas of South Carolina than in Louisiana because of higher numbers of individuals per visit, higher seed consumption and seed dropping rates, and longer foraging durations. Within South Carolina, more seeds were dispersed and dropped in spoil areas than in forests because of higher numbers of birds per visit. These findings show that among habitats, tallow tree attracts diverse but variable coteries of dispersal agents that are qualitatively similar in seed usage patterns. We suggest that its generalized dispersal syndrome contributes to effective seed dispersal by many bird species throughout its range. Effects of differential avian use among locales may include changes in local bird communities, and differing tallow tree demographics and invasion patterns.

Generalized avian dispersal syndrome contributes to Chinese tallow tree (Sapium sebiferum, Euphorbiaceae) invasiveness

1. Vertebrates are important seed dispersers for many plants, particularly those inhabiting naturally fragmented habitats such as lakes and wetlands. Such dispersal often takes place through the transport of ingested seeds (endozoochory). 2. Endozoochorous passage of seeds is likely to vary among both disperser and dispersed species. We hypothesized that seed retention time and survival of gut passage varies among disperser species (here Anas ducks) and is influenced by intraspecific differences in seed size. 3. Wigeongrass (Ruppia maritima) seeds were ingested by five duck species; Teal, Wigeon, Shoveler, Pintail and Mallard. Defecated seeds were recovered and germinated. 4. Total retrieval and germination of seeds, patterns of retrieval over time and seed weight before and after gut passage did not differ among duck species. Hence interspecific differences among Anas ducks and intraspecific differences in seed weight do not affect seed retention time or the response of seeds to gut passage. 5. Germination of retrieved seeds was influenced by the retention time in the gut, with seeds voided earlier more likely to germinate than those voided later. 6. The probability of dispersal at different retention times by any given duck was low. However, when considering the thousands of ducks moving among wetlands, the dispersal probabilities of seeds become significant. 7. Estimation of seed dispersal distance as a function of retention time suggested higher dispersal probabilities for seeds voided earlier. Based on average flight speeds ranging from 10 to 70 km h1, most probable dispersal distances range from 40 to 280 km. Dispersal over greater distances is possible, but less likely [KEYWORDS: Dabbling ducks; endozoochory; gut passage; seed dispersal; seed weight]

Effect of ingestion by five avian dispersers on the retention time, retrieval and germination of Ruppia maritima seeds

The cultivation of plants for the production of hydrocarbon fuels is gaining global momentum. These biofuels offer potential benefits as alternatives to fossil fuels, but mitigating any environmental risks posed by large-scale cultivation of bioenergy feedstock (biofeedstock) species poses new challenges: some proposed biofuel crops have become naturalized, and even invasive; the relative risks and benefits of growing monocultures versus polycultures of biofeedstock species require more thorough examination; and prompt development of a robust ecological risk assessment framework and careful screening are needed before these biofuel species are widely cultivated. Greater collaboration between agronomists developing crops for biofeedstock production and invasion biologists could substantially lower the risk of new plant invasions.

Screening bioenergy feedstock crops to mitigate invasion risk

We used seed traps (n = 119) to quantify seed dispersal of the Chinese tallow tree (Sapium sebiferum (L.) Roxb.) by birds in South Carolina during the October 1995 to April 1996 fruiting season. We tested if crop size, habitat type (spoil area vs. forest) and tree distribution (isolated vs. clustered) affected the dispersal efficiency and number of seeds dispersed from tallow trees. Traps captured 55,275 seeds and 107,993 functional locules; birds removed 48.8% of the available seeds. After scaling for canopy area of sample units (1570 m2; n = 32), birds removed an estimated 675,000 ± 56,000 of 1,681,000 ± 113,000 seeds, about 40% of the total seed crop. There was a trend for forest units to have greater dispersal efficiency than spoil area units but isolated and clustered trees were similar. Crop size was not a significant predictor of dispersal efficiency in either habitat but was an excellent predictor of the number of seeds dispersed in both habitats. The most productive unit was the only one...

https://bioone.org/journals/The-American-Midland-Naturalist/volume-144/issue-1/0003-0031(2000)144[0202:SDOTCT]2.0.CO;2/Seed-Dispersal-of-the-Chinese-Tallow-Tree-Sapium-sebiferum-L/10.1674/0003-0031(2000)144[0202:SDOTCT]2.0.CO;2.pdf

Ian J. Renne

Papers

Seed Dispersal of the Chinese Tallow Tree (Sapium sebiferum (L.) Roxb.) by Birds in Coastal South Carolina