The role of saltwort (Batis maritima L.) in regeneration of degraded mangrove forests

While saltwort (Batis maritima L.) is common in the fringe mangrove forests of southwest Florida, its role in regeneration of degraded mangrove communities is not known. Given the potential encroachment and subsequent degradation of mangrove communities by sea-level rise, it is important to quantify the effect of early-colonizing vegetation to early mangrove seedling survival. A greater number of mangrove seedlings were observed in existing B. maritima patches compared to surrounding mudflats. A planting experiment was designed to determine whether B. maritima was responsible for the observed pattern. Black mangrove (Avicennia germinans L.) seedlings, raised in a nursery, were planted in previously established B. maritima patches and on mudflats with and without nursery-raised B. maritima. There was significantly lower mortality of A. germinans seedlings when planted in existing B. maritima patches (69%), compared to seedlings planted on the mudflats (93%), demonstrating that existing B. maritima improved A. germinans seedling survival. Nursery-raised B. maritima had lower mortality on open mudflats (28%), suggesting that it can tolerate conditions, which make it an early colonizer of newly available habitats. The primary mechanism proposed for improving seedling success is a slight increase in elevation provided by the dense root network of established B. maritima. These findings have implications for scientists and managers anticipating the response of mangroves to sea-level rise.     

Theories for ecological restoration in changing environment: Toward ‘futuristic’ restoration

Ecological restoration is one of the fastest growing fields in applied ecology providing new ideas and opportunities for biological conservation and natural resource management. Despite countless attempts in the past, large portions of restoration projects have been considered unsuccessful mainly due to: unrealistic goals; inadequate restoration plans based on an ad-hoc approach; lack of explicit and quantified evaluation criteria for restoration success; lack of ecological understanding; social, economic, and political constraints; or combinations of these factors. Existing ecological theories, particularly succession theories, may provide a conceptual framework for a restoration trajectory. However, projecting a desirable trajectory and outcome is often challenged by the unpredictability of ecological communities in the changing environment. Particularly, the sustainability of reconstructed historic ecosystems appears to be an unlikely goal in the ever-changing and unpredictable future environment. This paper calls for a shift in the restoration paradigm from historic to futuristic. A futuristic restoration is: (i) to set realistic and dynamic (instead of static) goals for future, instead of past, environment; (ii) to assume multiple trajectories acknowledging the unpredictable nature of ecological communities and ecosystems; (iii) to take an ecosystem or landscape approach, instead of ad-hoc gardening, for both function and structure; (iv) to evaluate the restoration progress with explicit criteria, based on quantitative inference; and (v) to maintain long-term monitoring of restoration outcomes. A theoretical framework for futuristic restoration, in terms of goals, trajectories, evaluation criteria, and monitoring, along with a historical perspective is presented in this paper.     

铅锌矿渣场植被自然演替与基质的交互效应

矿业废弃地生态系统自然恢复的植被演替过程与机理是生态恢复研究的重要内容之一.以空间代替时间的方法,选择立地条件基本一致的4个不同自然恢复年限铅锌矿区为对象,研究黔西北土法炼锌渣场废弃地植被自然演替与矿渣基质理化性质的交互效应.结果表明： 随着堆置时间的增加,矿渣基质的营养条件明显得到改善,全氮、全磷和全钾含量极显著增加, pH上升,电导率下降,容重降低,有效铅和镉显著降低. 同时,随着恢复时间的增长,植物群落的物种丰富度、多样性指数和均匀度也相应提高.植物群落组成以多年生草本植物为主,植物群落演替在前20年较为缓慢,30年后植被群落盖度可达到53%,超过40年盖度可达87%.矿渣理化性质与物种多样性显著相关,典型变量分别是全氮、全磷和全钾;物种多样性指数与有效铅和镉呈显著负相关.土法炼锌渣场废弃地植被自然演替过程在30年后速度加快,植被生长的限制因子是营养供给不足和重金属的有效性高.     

Limits to convergence of vegetation during early primary succession

Questions: Primary succession, measured by changes in species composition, is slow, usually forcing a chronose‐quence approach. A unique data set is used to explore spatial and temporal changes in vegetation structure after a 1980 volcanic eruption. On the basis of data from a transect of 20 permanent plots with an altitudinal range of 250 m sampled through 2005, two questions are asked: Do changes along the transect recapitulate succession? Do plots converge to similar composition over time? Location: A ridge between 1218 and 1468 m on Mount St. Helens, Washington, USA. Methods: Repeat sampling of plots for species cover along a 1‐km transect. Floristic changes were characterized by techniques including DCA, clustering and similarity. Results: Species richness and cover increased with time at rates that decreased with increasing elevation. The establishment of Lupinus lepidus accelerated the rate of succession and may control its trajectory. Diversity (H) at first increased with richness, then declined as dominance hierarchies developed. Primary succession was characterized by overlapping phases of species assembly (richness), vegetation maturation (diversity peaks, cover expands) and inhibition (diversity declines). Each plot passed through several community classes, but by 2005, only four classes persisted. Succession trajectories (measured by DCA) became shorter with elevation. Similarity between groups of plots defined by their classification in 2005 did not increase with time. Similarity within plot groups converged slightly at the lower elevations. Despite similarities between temporal and spatial trends in composition, trajectories of higher plots do not recapitulate those of lower plots, apparently because Lupinus was not an early colonist. Any vegetation convergence has been limited to plots that are in close proximity.     

Seasonal composition and temporal succession of necrophagous and predator beetles on pig carrion in central Argentina

Insects are the most important components of the terrestrial fauna associated with carrion because they recycle organic matter back into the ecosystem. They can be classified into four ecological categories comprising: necrophages; parasites and predators of necrophagous species; omnivores, and incidentals. To determine the composition and temporal succession of necrophagous and predator beetles on pig carrion, four experiments, one in each season, were carried out during 2004 in a rural area of Cordoba, central Argentina. Two pigs (Sus scrofa L.), weighing approximately 8 kg each, were used in each of the four experiments. The animals were killed by a sharp blow to the head and immediately placed in an appropriate trap. One pig was placed in the shade and the other in direct sunlight. Beetle fauna were collected daily during the first 4 weeks and thereafter every 2 or 3 days. Five stages of decomposition were observed and a total of 1586 adults and 4309 immatures of Coleoptera belonging to the Staphylinidae, Nitidulidae, Cleridae, Dermestidae, Histeridae, Anthicidae and Trogidae families were collected during the four experiments. The necrophagous community was represented by Dermestes maculates (De Geer), nitidulid species and members of the Trox genus. Staphylinidae, Cleridae and Histeridae species were considered to be the main predators of the necrophagous species.     

Improving oral bioavailability of cyclic peptides by N-methylation

The renaissance of peptides in pharmaceutical industry results from their importance in many biological functions. However, low metabolic stability and the lack of oral availability of most peptides is a certain limitation. Whereas metabolic instability may be often overcome by development of small cyclic peptides containing d-amino acids, the very low oral availability of most peptides is a serious limitation for some medicinal applications. The situation is complicated because a twofold optimization – biological activity and oral availability – is required to overcome this problem. Moreover, most simple “rules” for achieving oral availability are not general and are applicable only to limited cases. Many structural modifications for increasing biological activities and metabolic stabilities of cyclic peptides have been described, of which N-alkylation is probably the most common. This mini-review focuses on the effects of N-methylation of cyclic peptides in strategies to optimize bioavailabilities.     

Regional Dissociation of Cyclic AMP and Inositol Phosphate Formation in Response to Thyrotropin-Releasing Hormone in the Rat Brain

The present study was undertaken to define effects of thyrotropin-releasing hormone (TRH) on formation of cyclic AMP (cAMP) and inositol phosphates (IPs) in rat brain regions. The brain of male Wistar rats was dissected into seven discrete regions, and each region was sliced. The slices were incubated in Krebs-Henseleit glucose buffer containing varying doses of TRH. TRH caused a significant and consistent increase in cAMP level, but not in formation of IPs, in the hypothalamus, striatum, and midbrain. TRH stimulated formation of IPs in the cerebellum, where the tripeptide did not change the cAMP level. In contrast, formation of neither cAMP nor IPs was affected by TRH in the cortex, hippocampus, or pons-medulla. These data suggest that TRH possesses two distinct types of brain intracellular signaling systems, which vary with brain regions.     

Effects of cyclic irrigation on water and nitrogen mass balances in a paddy field

Cyclic irrigation is considered an effective water management practice for reducing pollutant loads from a paddy-field district. The objective of this study was to clarify the effects of cyclic irrigation on mass balance in paddy plots. At the study site, cyclic irrigation with a high cyclic irrigation ratio (% reused water in irrigation water) was conducted from late April to late June. We found a complementary relationship between the volume of irrigation water and rainfall, which together totaled about 1400-1600 mm during the irrigation period each year. We concluded that a cyclic irrigation system that enables the paddy-field district to use a high cyclic irrigation ratio may lead to more efficient use of rainfall for crop irrigation. Nitrogen concentrations in both irrigation water and ponded water tended to be higher during the cyclic irrigation period than during the lake water irrigation period. Nitrogen input from irrigated water accounted for about 8-16% of the total input of nitrogen. It is suggested that fertilizer application of nitrogen can be reduced by its return through cyclic irrigation.     

Ecosystem productivity can be predicted from potential relative growth rate and species abundance

We show that ecosystem-specific aboveground net primary productivity (SANPP, g g⁻¹ day⁻¹, productivity on a per gram basis) can be predicted from species-level measures of potential relative growth rate (RGR_max), but only if RGR_max is weighted according to the species' relative abundance. This is in agreement with Grime's mass-ratio hypothesis. Productivity was measured in 12 sites in a French Mediterranean post-agricultural succession, while RGR_max was measured on 26 of the most abundant species from this successional sere, grown hydroponically. RGR_max was only weakly correlated ( r ² = 0.12, P  < 0.05) with field age when species abundance was not considered, but the two variables were strongly correlated ( r ² = 0.81, P  < 0.001) when the relative abundance of species in each field was taken into account. SANPP also decreased significantly with field age. This resulted in a tight relationship ( r ² = 0.77, P  < 0.001) between productivity and RGR_max weighted according to species relative biomass contribution. Our study shows that scaling-up from the potential properties of individual species is possible, and that information on potential and realized species traits can be integrated to predict ecosystem functioning.     

The effect of fructose 2,6-bisphosphate and AMP on the activity of phosphorylated and unphosphorylated fructose-1,6-bisphosphatase from rat liver

Rat liver fructose-1,6-bisphosphatase was partially phosphorylated in vitro and separated into unphosphorylated and fully phosphorylated enzyme. The effects of fructose 2,6-bisphosphate and AMP on these two enzyme forms were examined. Unphosphorylated fructose-1,6-bisphosphatase was more easily inhibited by both effectors. Fructose 2,6-bisphosphate affected both K0.5 and Vmax, while the main effect of AMP was to lower Vmax. Fructose 2,6-bisphosphate and AMP together acted synergistically to decrease the activity of fructose-1,6-bisphosphatase, and since unphosphorylated and phosphorylated enzyme forms are affected differently, this might be a way to amplify the effect of phosphorylation.