No abstract

Casuarina cunninghamiana Miq. is an important rheophytic tree in New South Wales, Australia because it is fast growing and can tolerate flood disturbance. Widden Brook is an active sand-bed stream that has widened substantially since initial European settlement in the early 1800s and is characterized by high flood variability and multi-decadal periods of alternating high and low flood frequency, called flood-and drought-dominated regimes. Channel contraction by bench formation is currently occurring. Conversion of coarse-grained point bars to benches is an important process of channel contraction. When point bars grow to a height where suspended sediment is first deposited to thicknesses of at least 50 mm by sub-bankfull floods, rapid establishment of C. cunninghamiana occurs. As the trees grow they partially block bankside flows, thereby locally reducing flow velocity and inducing further deposition on the benches. Such synergistic relationships between bar height and inundation, fine-grained sediment deposition, tree establishment and the development of a bankside low current velocity zone are fundamental for bench development. Size-class frequency data demonstrate that C. cunninghamiana on the benches consists of pure even-aged stands with most trees clustering near the average diameter. Two benches have similar size class frequency distributions but a third has significantly smaller trees. Recruitment on benches is episodic, may occur in areas open to grazing and is dependent on favourable conditions that allow tree survival. These favourable conditions include high seed availability, low levels of competition, deposition of fine sediments and adequate moisture for tree growth. Although C. cunninghamiana germinates on bars, seedlings are eliminated by prolonged inundation or flood scour and do not reach maturity. Recurring catastrophic floods or a sequence of large floods in rapid succession episodically destroy benches by substantial channel widening and initiate a new phase of bar and bench development. A conceptual model of the conversion of point bars to benches by thick mud deposition and C. cunninghamiana recruitment has been developed for sand-bed streams draining similar sandstone catchments. Figure 4. Channel cross sections and bench sediments of (A) upstream right bank bench, (B) upstream unvegetated section (sand splay) of downstream right bank bench, and (C) downstream section of downstream right bank bench.Figure 5. Bivariate plots of graphic mean size versus (A) inclusive graphic standard deviation and (B) inclusive graphic skewness, showing that the bench nucleus sediments are similar to the adjacent bed and bar sediments.Figure 6. Size-class (DBH) distributions of live (white) and dead (black) stems of C. cunninghamiana on (A) upstream right bank bench, n = 510; (B) downstream right bank bench, n = 275; (C) left bank bench, n = 139.Figure 7. Model of bench development and growth from a point bar, and bench destruction by catastrophic floods or a sequence of large floods in rapid succession.

Rewilding is emerging as a major issue in conservation. However, there are currently a dozen definitions of rewilding that include Pleistocene rewilding, island rewilding, trophic rewilding, functional rewilding and passive rewilding, and these remain fuzzy, lack clarity and, hence, hinder scientific discourse. Based on current definitions, it is unclear how the interventions described under the rewilding umbrella differ from those framed within the long-standing term 'restoration'. Even projects held up as iconic rewilding endeavours invariably began as restoration projects (e.g., Oostvaaderplassen; Pleistocene Park; the return of wolves to Yellowstone, etc.). Similarly, rewilding organisations (e.g., Rewilding Europe) typically began with a restoration focus. Scientific discourse requires precise language. The fuzziness of existing definitions of rewilding and lack of distinction from restoration practices means that scientific messages cannot be transferred accurately to a policy

Euphorbia tirucalli is a succulent shrub or small tree that is native to the African continent, however, it is widely cultivated across the globe due to its use in traditional medicines to treat ailments, ranging from scorpion stings to HIV. Recent studies have identified compounds present in the latex of the plant, including a range of bi- and triterpenoids that exhibit bioactivity, including anticancer activity. This study aimed to optimize water extraction conditions for high-yield total phenolic content recovery, to prepare methanol and aqueous extracts from the aerial sections of the plant, and to test the phytochemical, antioxidant, and anti-cancer properties of these extracts. Water extraction of total phenolic compounds (TPC) was optimized across a range of parameters including temperature, extraction time, and plant mass-to-solvent ratio. The water extract of the E. tirucalli powder was found to contain TPC of 34.01 mg GAE (gallic acid equivalents)/g, which was approximately half that of the methanol extract (77.33 mg GAE/g). The results of antioxidant assays showed a uniform trend, with the methanol extract’s antioxidant reducing activity exceeding that of water extracts, typically by a factor of 2:1. Regression analysis of the antioxidant assays showed the strongest correlation between extract TPC and antioxidant activity for the ABTS (2,2-azino-bis(3-ethyl-benzothiazoline-6-sulfonic acid) and DPPH (2,2-diphenyl-1-picrylhydrazyl) methods. The methanol extract also showed greater growth inhibition capacity towards the MiaPaCa-2 pancreatic cancer cell line. These data suggest that further investigations are required to confirm the source of activity within the E. tirucalli leaf and stems for potential use in the nutraceutical and pharmaceutical industries.

No abstract