Diurnal temperature range as a key predictor of plants' elevation ranges globally.

A prominent hypothesis in ecology is that larger species ranges are found in more variable climates because species develop broader environmental tolerances, predicting a positive range size-temperature variability relationship. However, this overlooks the extreme temperatures that variable climates impose on species, with upper or lower thermal limits more likely to be exceeded. Accordingly, we propose the 'temperature range squeeze' hypothesis, predicting a negative range size-temperature variability relationship. We test these contrasting predictions by relating 88,000 elevation range sizes of vascular plants in 44 mountains to short- and long-term temperature variation. Consistent with our hypothesis, we find that species' range size is negatively correlated with diurnal temperature range. Accurate predictions of short-term temperature variation will become increasingly important for extinction risk assessment in the future.

Fellowship of the Spring: An initiative to document and protect the world's oases.

An 'oasis' signifies a refugium of safety, recovery, relaxation, fertility, and productivity in an inhospitable desert, a sweet spot in a barren landscape where life-giving water spills forth from the Earth. Remarkable mythological congruencies exist across dryland cultures worldwide where oases or 'arid-land springs' occur. In many places they also provide specialised habitats for an extraordinary array of endemic organisms. To inform their management, and maintain their integrity, it is essential to understand the hydrogeology of aquifers and springs. Gravity-fed vs artesian aquifers; actively recharged vs fossil aquifers, and sources of geothermal activity are important concepts presented here. There consequences for oases of sustainable and unsustainable groundwater extraction, and other examples of effective conservation management. Oases are archetypes for human consciousness, habitats that deserve protection and conservation, and a lingua franca for multicultural values and scientific exchange. We represent an international Fellowship of the Spring seeking to encompass and facilitate the stewardship of oases and aquifers through improved knowledge, outreach, and governance.

Past climatic refugia and landscape resistance explain spatial genetic structure in Oriental beech in the South Caucasus.

Predicting species-level effects of climatic changes requires unraveling the factors affecting the spatial genetic composition. However, disentangling the relative contribution of historical and contemporary drivers is challenging. By applying landscape genetics and species distribution modeling, we investigated processes that shaped the neutral genetic structure of Oriental beech (Fagus orientalis), aiming to assess the potential risks involved due to possible future distribution changes in the species. Using nuclear microsatellites, we analyze 32 natural populations from the Georgia and Azerbaijan (South Caucasus). We found that the species colonization history is the most important driver of the genetic pattern. The detected west-east gradient of genetic differentiation corresponds strictly to the Colchis and Hyrcanian glacial refugia. A significant signal of associations to environmental variables suggests that the distinct genetic composition of the Azerbaijan and Hyrcanian stands might also be structured by the local climate. Oriental beech retains an overall high diversity; however, in the context of projected habitat loss, its genetic resources might be greatly impoverished. The most affected are the Azerbaijan and Hyrcanian populations, for which the detected genetic impoverishment may enhance their vulnerability to environmental change. Given the adaptive potential of range-edge populations, the loss of these populations may ultimately affect the specie's adaptation, and thus the stability and resilience of forest ecosystems in the Caucasus ecoregion. Our study is the first approximation of the potential risks involved, inducing far-reaching conclusions about the need of maintaining the genetic resources of Oriental beech for a species' capacity to cope with environmental change.

Environmental drivers and spatial scaling of species abundance distributions in Palaearctic grassland vegetation.

Species abundance distributions (SADs) link species richness with species abundances and are an important tool in the quantitative analysis of ecological communities. Niche-based and sample-based SAD models predict different spatial scaling properties of SAD parameters. However, empirical research on SAD scaling properties is largely missing. Here we extracted percentage cover values of all occurring vascular plants as proxies of their abundance in 1725 10-m2 plots from the GrassPlot database, covering 47 regional data sets of 19 different grasslands and other open vegetation types of the Palaearctic biogeographic realm. For each plot, we fitted the Weibull distribution, a model that is able to effectively mimic other distributions like the log-series and lognormal, to the species-log abundance rank order distribution. We calculated the skewness and kurtosis of the empirical distributions and linked these moments, along with the shape and scale parameters of the Weibull distribution, to plot climatic and soil characteristics. The Weibull distribution provided excellent fits to grassland plant communities and identified four basic types of communities characterized by different degrees of dominance. Shape and scale parameter values of local communities on poorer soils were largely in accordance with log-series distributions. Proportions of subdominant species tended to be lower than predicted by the standard lognormal SAD. Successive accumulation of plots of the same vegetation type yielded nonlinear spatial scaling of SAD moments and Weibull parameters. This scaling was largely independent of environmental correlates and geographic plot position. Our findings caution against simple generalizations about the mechanisms that generate SADs. We argue that in grasslands, lognormal-type SADs tend to prevail within a wider range of environmental conditions, including more extreme habitats such as arid environments. In contrast, log-series distributions are mainly restricted to comparatively species-rich communities on humid and fertile soils.

The combined effects of climate and canopy cover changes on understorey plants of the Hyrcanian forest biodiversity hotspot in northern Iran.

Understanding forest understorey community response to environmental change, including management actions, is vital given the understorey's importance for biodiversity conservation and ecosystem functioning. The Natural World Heritage Hyrcanian temperate forests (Iran) provide an ideal template for furnishing an appreciation of how management actions can mitigate undesired climate change effects, due to the forests' broad environmental gradients, isolation from colonization sources and varied light environments. We used records of 95 understorey plant species from 512 plots to model their probability of occurrence as a function of contemporary climate and soil variables, and canopy cover. For 65 species with good predictive accuracy, we then projected two climate scenarios in the context of either increasing or decreasing canopy cover, to assess whether overstorey management could mitigate or aggravate climate change effects. Climate variables were the most important predictors for the distribution of all species. Soil and canopy cover varied in importance depending on understorey growth form. Climate change was projected to negatively affect future probabilities of occurrence. However, management, here represented by canopy cover change, is predicted to modify this trajectory for some species groups. Models predict increases in light-adapted and generalist forbs with reduced canopy cover, while graminoids and ferns still decline. Increased canopy cover is projected to buffer an otherwise significant decreasing response of cold-adapted species to climate change. However, increasing canopy cover is not projected to buffer the predicted negative impact of climate change on shade-adapted forest specialists. Inconsistent responses of different species and/or growth forms to climate change and canopy cover reflect their complicated life histories and habitat preferences. Canopy cover management may help prevent the climate change induced loss of some important groups for biodiversity conservation. However, for shade-adapted forest specialists, our results imply a need to adopt other conservation measures in the face of anticipated climate change.

Essential-oil and fatty-acid composition, and antioxidant activity of extracts of Ficaria kochii.

The essential-oil and fatty-acid composition of the aerial parts of Ficaria kochii (Ledeb.) Iranshahr & Rech.f. native to Iran, and the antioxidant activity of various extracts of this plant were examined. The study by GC-FID and GC/MS analysis of the essential oil resulted in the identification of 61 compounds, representing 86.01% of the total oil composition. Phytol (10.49%), farnesol (7.72%), methyl linoleate (5.57%), and α-farnesene (4.96%) were the main components. The fatty-acid composition of the aerial parts of F. kochii was also analyzed by GC/MS. The major components were palmitic acid (25.9%), linolenic acid (25.3%), and linoleic acid (17.5%). Polyunsaturated fatty acids (PUFAs) were found in higher amounts than saturated fatty acids. The possible antioxidant activity of various extracts (prepared by using solvents with different polarity) of the F. kochii aerial parts was evaluated by screening for their 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging activity, Fe(III) -reducing power, total antioxidant activity, and inhibitory activity in the linoleic acid-peroxidation system. H(2) O proved to be the most efficient solvent for the extraction of antioxidants, as the H(2) O extract contained the highest amount of phenolic compounds (2.78±0.23 GAE/g dry matter) and also exhibited the strongest antioxidant capacity in all the assays used. The results of the present investigation demonstrated that the aerial parts of F. kochii can be used as natural and safe nutrition supplement in place of synthetic ones.

Interaction of different extracts of Primula heterochroma Stapf. with red blood cell membrane lipids and proteins: antioxidant and antihemolytic effects.

In recent years, considerable attention has been paid to plants as potent natural drugs for their ameliorative roles against free-radical-mediated oxidative stress. Therefore, their interactions with cell membrane lipids and proteins, which generally serve as primary targets of lipid peroxidation, are of much interest. In the current investigation, in vitro and ex vivo studies are performed in order to estimate possible effects of different extracts of Primula heterochroma Stapf. on red blood cell membranes of rat erythrocytes using colorimetric methods. The results indicate that binding of the extracts to lipids and proteins of red blood cell membranes both significantly inhibits lipid peroxidation, and also increases red blood cell integrity against hemolysis. Moreover, a polyphenol extract, in particular, demonstrates notable antihemolytic activity in hydrogen peroxide-induced hemolysis model (IC(50) = 199.49 ± 9.1 µg ml(-1)).

Antioxidant, antihemolytic, and inhibitory activities of endemic Primula heterochroma against Fe2+-induced lipid peroxidation and oxidative stress in rat brain in vitro.

CONTEXT: The genus Primula (Primulaceae) has been used in traditional medicine to treat convulsion and microbial or viral infections. OBJECTIVE: In the present study, we evaluate antioxidant, antihemolytic, and protective effects of flavonoid-rich fractions of endemic Primula heterochroma Stapf. (Primulaceae) against Fe(2+)-induced lipid peroxidation and oxidative stress in rat brain in vitro. MATERIALS AND METHODS: Aerial parts of plant were defatted and extracted with 60% acetone. Then, 60% acetone extract was fractionated sequentially with n-hexane, ethyl acetate, and water. Antioxidant activity of fractions was evaluated by employing six different assays, i.e., 1,1-diphenyl-2-picryl hydrazyl (DPPH) and hydrogen peroxide scavenging, metal chelating and reducing power activities and hemoglobin-induced linoleic acid system and Fe(2+)-induced lipid peroxidation and oxidative stress in rat brain. Also, its antihemolytic activity was determined using 2,2'-azobis(2-amidinopropane) dihydrochloride-induced hemolysis in rat erythrocyts. RESULTS: Among the flavonoid-rich fractions of Primula heterochroma, aqueous fraction demonstrated the most protective effect through decreasing brain thiobarbituric acid reactive substances (TBARS) levels at a dose 200 µg mL(-1) (40%, p < 0.001 versus iron group). Also, the aqueous fraction showed better activity in Fe(2+) chelating (89 ± 3.8 µg mL(-1)) and DPPH radical scavenging (394.4 ± 18.4 µg mL(-1)) models than other fractions. The probable protective mechanism of flavonoid-rich fractions may be attributed to their Fe(2+) chelating, DPPH radical scavenging and reducing power activities. Also, the n-hexane fraction demonstrated a higher protective effect in the hemoglobin-induced linoleic acid system and 2,2'-azobis(2-amidinopropane) dihydrochloride-induced hemolysis (67 ± 2.6 µg mL(-1)). DISCUSSION AND CONCLUSION: Results of this study demonstrate Primula heterochroma is a rich source of natural antioxidant compounds.

Protective effects of Allium paradoxum against gentamicin-induced nephrotoxicity in mice.

Allium paradoxum (M.Bieb.) G. Don is a locally known vegetable and is utilized for preparation a variety of local foods in northern of Iran. This study was conducted to quantitatively evaluate the recovery effects of A. paradoxum on gentamicin-induced nephrotoxicity in mice. The curative effect of extracts from the aerial parts and bulbs of A. paradoxum against gentamicin-induced renotoxicity in mice was determined. Both extracts at the dose 200 mg kg(-1) day(-1) offered nephroprotective effect by change in the blood urea nitrogen and creatinine. No statistical difference could be obtained in serum creatinine and blood urea nitrogen of bulb-treated mice compared to normal mice. The result show that bulb extract at 200 mg kg(-1) day(-1) has better activity than aerial parts.

Vegetation mapping of the Mond Protected Area of Bushehr Province (south-west Iran).

Arid regions of the world occupy up to 35% of the earth's surface, the basis of various definitions of climatic conditions, vegetation types or potential for food production. Due to their high ecological value, monitoring of arid regions is necessary and modern vegetation studies can help in the conservation and management of these areas. The use of remote sensing for mapping of desert vegetation is difficult due to mixing of the spectral reflectance of bright desert soils with the weak spectral response of sparse vegetation. We studied the vegetation types in the semiarid to arid region of Mond Protected Area, south-west Iran, based on unsupervised classification of the Spot XS bands and then produced updated maps. Sixteen map units covering 12 vegetation types were recognized in the area based on both field works and satellite mapping. Halocnemum strobilaceum and Suaeda fruticosa vegetation types were the dominant types and Ephedra foliata, Salicornia europaea-Suaeda heterophylla vegetation types were the smallest. Vegetation coverage decreased sharply with the increase in salinity towards the coastal areas of the Persian Gulf. The highest vegetation coverage belonged to the riparian vegetation along the Mond River, which represents the northern boundary of the protected area. The location of vegetation types was studied on the separate soil and habitat diversity maps of the study area, which helped in final refinements of the vegetation map produced.