Academic literature on the topic 'Acacia stenophylla'

Seedling liners of sweet acacia (Acacia smallii), shoestring acacia (Acacia stenophylla), palo brea (Cercidium praecox), and Chilean mesquite (Prosopis chilensis) were potted on 1 June 1993 into 27-liter (#5) black polyethylene containers filled with a 70% ponderosa pine forest mulch, 15% sand, and 15% silt (by volume) rooting medium. Just before potting, the inner wall of one-half of the containers of each species was painted with a latex paint impregnated with cupric hydroxide; the remaining containers were unpainted as a control treatment. Trees were then grown for 5 months in an outdoor container production nursery at a spacing distance of 45 cm. All trees were irrigated and fertilized according to standard nursery practices. The effect of cupric-hydroxide-painted containers (CHPC) on tree growth was species specific. Compared with nonpainted controls, CHPC caused roots to become more branched and decreased shoot lateral branch number and extension lengths of sweet acacia and shoestring acacia. CHPC also decreased height of shoestring acacia, but did not affect height of sweet acacia or root and shoot dry weight of sweet acacia and shoestring acacia. Shoot and root dry weight, height, and shoot lateral branch number and extension lengths of Chilean mesquite in CHPC were all increased compared with nonpainted controls. CHPC did not affect root branching of Chilean mesquite. Also, CHPC did not affect any measured growth variable of palo brea.

Seedling liners of four southwestern desert landscape trees, Acacia smallii, Acacia stenophylla, Cercidium praecox, and Prosopis chilensis, were potted into black polyethylene containers either painted on the inner wall with a latex paint containing cupric hydroxide [Cu(OH)2] or unpainted. Tree seedlings were then grown for five months in an outdoor container production nursery and evaluated for effects of Cu(OH)2-treated containers on tree growth. No foliar copper toxicity symptoms were observed on any species during the study. In comparison with unpainted containers, Cu-treated containers increased root branching frequency, reduced shoot extension, and lowered the number of primary shoot lateral branches of sweet acacia and shoestring acacia. Cu-treated containers also decreased height of shoestring acacia. Chilean mesquite grew taller and larger with increased shoot and root dry weights in Cu-treated containers in comparison with those in unpainted containers. However, effects of Cu-treated containers on growth of Chilean mesquite were not related to any changes in root branching frequency. Growth of palo brea and root-to-shoot ratios of all four tree species were not affected by Cu-treated containers.

Soil communities exert strong influences on the processing of organic matter and nutrients. Plantations of trees, especially of nitrogen fixing ones, may affect the soil macrofauna through litter quality and quantity. This study was conducted in a randomized block design with three blocks consisting of Populus euphratica, Eucalyptus camaldulensis, Eucalyptus microtheca, Acacia farnesiana, Acacia salicina, Acacia saligna, Acacia stenophylla and Dalbergia sissoo monoculture plantations that were established in 1992. Soils and soil macrofauna were sampled in November 2006. Leaf litterfall was collected from November 2006 to November 2007 at bi-weekly intervals. Macroinvertebrate abundance and biomass were consistently higher in A. salicina plantations than in the others, whereas they were lowest in E. camaldulensis. Tree species and nitrogen fixing trees significantly influenced the soil macrofauna richness. The results suggest that the earthworm distribution is regulated by leaf litter quality (Ca, C and N) whereas the macrofauna richness is regulated by leaf litter mass, soil organic carbon and leaf litter Mg. Totally, it was revealed that the tree species clearly affected macrofauna whereas nitrogen fixation did not.  

Symbiotic relationships between legumes and nitrogen-fixing soil micro-organisms are of ecological importance in plant communities worldwide. For example, nutrient-poor Australian soils are often dominated by shrubby legumes (e.g. species of Acacia). However, relatively few studies have quantified patterns of diversity, host-specificity and effectiveness of these ecologically important plant–microbe interactions. In this study, 16S rRNA gene sequence and PCR-RFLP analyses were used to examine bacterial strains isolated from the root nodules of two widespread south-eastern Australian legumes, Acacia salicina and Acacia stenophylla, across nearly 60 sites. The results showed that there was extensive genetic diversity in microbial populations, including a broad range of novel genomic species. While previous studies have suggested that most native Australian legumes nodulate primarily with species of the genus Bradyrhizobium, our results indicate significant associations with members of other root-nodule-forming bacterial genera, including Rhizobium, Ensifer, Mesorhizobium, Burkholderia, Phyllobacterium and Devosia. Genetic analyses also revealed a diverse suite of non-nodulating bacterial endophytes, only a subset of which have been previously recorded. Although the ecological roles of these endosymbionts are not well understood, they may play both direct and indirect roles in promoting plant growth, nodulation and disease suppression.

The objective of the current work is to study the genetic differentiation between Acacia species growing in Egypt as plant genetic resources based on morphological, biochemical, and molecular markers. The 20 replicates of Acacia tree collected from four localities from Egypt were A. tortilis ssp. raddiana and A. farnesiana (Siwa Oasis and Borg El-Arab City), A. stenophylla, A. sclerosperma (Marsa Matroh City), and A. saligna (Abis Station Farm, Alexandria). The results based on the previous markers indicated highly significant differences between Acacia species, confirming the hypothesis of the possibility of using morphological, biochemical, and molecular parameters in species identification. Qualitative characteristics results indicated some similarities and differences that are taxonomically important for comparing taxonomical grouping with morphological data for the genetic description of Acacia species. The activities of antioxidant enzymes have been studied intensively and the results provide strong similarities between the Acacia species (69%), between A. raddiana (Siwa and Borg Al-Arab) and A. saligna, followed by all Acacia species (50%). Finally, the molecular studies showed that a total of 563 amplification fragments, 190 fragments were monomorphic, and 373 fragments were polymorphic. The highest number of amplification fragments (21) was detected with OPB-20 primer, while OPA-20 showed seven amplification fragments; the average number was 13.09. The results indicated that Acacia species exhibit high genetic differentiation, helpful in the future for genetic improvement programs. The novelty of the current study is highlighting the importance of plant genetic resources in Egypt and using different techniques to measure the differentiation between these species.

<p>Use of saline lands for agroforestry relies primarily on plant species that have the trait of salinity tolerance, and also other economic and agronomic benefits. The selection of species, however, also needs to consider other key factors such as compatibility with existing flora, and potential for environmental benefits such as improved soil fertility or lowering of the water table in the case of dryland salinity. The testing of candidate species in particular environments needs substantial investments of costs and time. In this paper, a novel approach is presented for the rapid identification of potentially salt tolerant <em>Acacia </em>species, based on molecular phylogenetic analysis. The approach has been applied to four species groups, <em>Acacia pendula, A. salicina, A. victoriae</em> and <em>A. stenophylla</em>. The nuclear-encoded ribosomal DNA internal and external transcribed spacer (ITS and ETS) regions were used as markers, and phylogenetic analyses undertaken to identify closely related species that may share the salt tolerance traits. Such a methodology could be used to more rapidly identify candidate native species for agroforestry in salinity-affected regions and for preventing further expansion of salinity, thus assisting in biodiversity conservation.</p>

The survival and growth of 24 native tree species planted in 2 trials on a saline discharge site, which had a soil salinity gradient as well as watertable depth and salinity, near Wellington in central-west New South Wales were investigated. Several provenances of some species (including Acacia stenophylla, Eucalyptus camaldulensis and E. spathulata) and clones of E. camaldulensis and E. spathulata, were also evaluated. Each accession was represented by a 5-tree row plot with 8 replications. Root-zone salinity (ECe 0–60 cm) at the tree and plot level was calculated from in situ measurements of bulk soil salinity using an EM-38 device (Geonics, Canada). Growth measurements are reported at 72 (trial 1) and 61 months (trial 2) after planting. For each trial, 4 replicates were classified as either non-saline (mean ECe <2 dS/m) or saline (ECe range from about 6 to 10 dS/m). Watertable depths varied from 0 to 1.5 m (depending on season) in the saline areas to >4 m in the non-saline, upslope areas. Survival and growth differed significantly between species, provenances and clones in both trials and under both saline and non-saline conditions. For most accessions, trees survived and grew better under non-saline conditions. Under non-saline conditions A. mearnsii, E. camaldulensis and E. occidentalis performed best; for example, A.�mearnsii (16268) attained a mean height of 7 m and mean DBH of 11 cm at 61 months in trial 2. Under saline conditions, A. stenophylla, E. camaldulensis, E. occidentalis and E. spathulata performed best; for example, E.�occidentalis attained a height of 6.9 m height and 12.3 cm DBH after 61 months in trial 2. Responses of selected species to root-zone salinity are provided; significant differences were found between species with E. occidentalis and A. stenophylla showing no growth decline up to ECe of 10 dS/m, while most other species showed varying rates of decline with increasing salinity. Three years after thinning each trial, good coppice regrowth was observed from cut stumps of all species except A. mearnsii and Melaleuca halmaturorum.

This thesis explores the hydrological factors that may contribute to the observed distribution patterns of invasive willows (Salix) and native trees (Eucalyptus camaldulensis, E. largiflorens and Acacia stenophylla) along the Lower River Murray (LRM) in southern Australia. An initial survey, establishing the diversity and flowering biology of Salix taxa was carried out to ascertain the extent of invasion, and the likelihood of hybridisation, which may accelerate invasion. S. babylonica, S. fragilis, S. × chrysochoma and S. × rubens occur in the study region, each represented by a single gender. None were present on floodplains, but the most dominant taxon, S. babylonica, occurred along the entire length of the main channel. No seed or seedlings were observed; hence reproduction is likely to be asexual. More detailed survey work was then carried out to characterise the distribution patterns of the dominant S. babylonica and co-occurring natives (Eucalyptus camaldulensis, E. largiflorens and Acacia stenophylla) along a hydrologic gradient produced by the extensive weir system in the LRM. In weir pools, variation in daily water levels of weir pools is low (± 0.1 m) immediately upstream of the weir, but higher immediately downstream (0.2-1.0 m daily). The distribution of natives was uniform across weir pools, while S. babylonica was more abundant above weir structures, suggesting low tolerance to variable water regimes. Hypotheses relating to the observed distribution patterns were then tested experimentally on juveniles of the S. babylonica, E. camaldulensis and A. stenophylla. The experiment was carried out in outdoor ponds using an orthogonal design, with four elevations in relation to water level (-25 cm, 0 cm +25 cm, + 50 cm) under each of three water regimes. Experimental water regimes manipulated the magnitude of daily water level changes (static, 0 m dayˉ¹ ; moderate, ± 0.05 - 0.15 m dayˉ¹; high, ± 0.2 -0.5 m dayˉ¹) to mimic typical hydrological conditions across weir pools in the LRM. Final biomass and mean relative growth rates (S. babylonica, 0.0403 ± 0.002 g mˉ²dayˉ¹ A. stenophylla, 0.0249 ± 0.0017 g m ˉ² dayˉ¹; E. camaldulensis, 0.0204 ± 0.0016g mˉ² dayˉ¹) of all 3 species were unaffected by water regimes (i.e. water fluctuations), but were affected by elevation. Survival of both S. babylonica and A. stenophylla was lowest at low elevations where inundation was high. At higher elevations (+25 cm, +50 cm) the RGR of S. babylonica juveniles was much higher than the native juveniles. To test if the persistence of adults of each species along hydrologic gradients were associated with differing tolerances to water deficits and water use characteristics, S. babylonica and native species were examined under typical hydrological conditions in the field and during an unusual drawdown. S. babylonica occurring at the lowest elevations on riverbanks, had the least negative predawn shoot water potential (ψpredawn), followed by the natives, which were at higher elevations. A. stenophylla had the lowest stable carbon isotope ratio (δ¹³C) values (by 1.7 ‰) on the riverbank; suggesting more profligate water use than S. babylonica and E. camaldulensis. However, all riverbank trees had significantly less negative ψpredawn and lower δ¹³C than native trees on floodplains, consistent with higher water availability on riverbanks. The position and stable oxygen isotope ratio (δ¹⁸O) values were consistent with riverbank S. babylonica sourcing their water directly from the river or from shallow soil-water sources (<0.25 m). In floodplain habitats, depth to water was > 2.5 m, and groundwater was 5 times more saline (4.97 ± 0.88 dS mˉ¹) than river-water. Native trees with deep roots, the ability to lower water potentials and alter water use efficiencies may be at an advantage in this habitat relative to S. babylonica. Extreme low flows in the LRM, over a 6-month period, provided an opportunity to assess how S. babylonica and E. camaldulensis responded to a river-water drawdown. During the drawdown, river-water levels fell at a rate of ~2 – 2.5 mm dayˉ¹ and dropped to a minimum of 0.42 m below the designated pool level. S. babylonica and E. camaldulensis maintained high ψpredawn across the drawdown period, most likely because riverbank soil water availability was not limited; as depth to water table only decreased marginally (≤0.15 m) and soil water content and soil water potential were high (<1.1 MPa). However, an above average rainfall in February 2003 significantly increased soil water potential in the upper 0.25 m of the riverbank, which correlated with a significant increase in ψpredawn in E. camaldulensis, suggesting they were able to use shallow, precipitation derived soil-water sources whereas S. babylonica were not. Also under hot, dry conditions, S. babylonica had higher transpiration rates and lower instantaneous water use efficiencies than co-occurring E. camaldulensis. This suggests that S. babylonica may consume larger volumes of water per unit leaf area than natives, if access to water is maintained.
Thesis (Ph.D.) - University of Adelaide, School of Earth and Environmental Sciences, 2010