Scientific analysis of indigenous techniques for guggal(Commiphora wightii) tapping in India

Guggal, a threatened species that is endemic to western India, is tapped to extract medicinally important oleo-gum-resin （guggul）. However, the plant dies after gum exudation. The indigenous tapping techniques used by local people were examined in Gujarat, India to dis-cover the scientific basis behind these techniques： selection of gum in-ducer, season of tapping, and plant parts to be tapped. First, the presence of Xanthomonas axonopodis pv. commiphorae （Xac） in the gum suspen-sion used for tapping was established. This bacterium induces gum ooz-ing from the tapped plants and later, causes them to die off. The popula-tion of Xac in gum was found to decrease with the age of the gum. With that, fresh gum increased the tapping success. Second, local people pre-ferred tapping during the warm season, which we validated by determin-ing that Xac growth was best at 30 ＆#176;C. Tapping during September （mean temperature 25.7-30.0 ＆#176;C） clearly favoured growth of the pathogen and yielded maximum guggul. Multiple tapping on a mature tree ensured maximum gum extraction before its death. Finally, application of in-digenous technology under natural plant stands by the local people en-sured availability of this important raw drug for consumption. Our study established that the age-old traditional methods have a strong scientific basis. However, it is imperative to formulate strategies based on con-temporary scientific understanding to protect this natural resource before it becomes extinct.

Carbon dioxide fluxes of tundra vegetation communities on an esker top in the low-Arctic

Previous studies have shown that carbon dioxide fluxes vary considerably among Arctic environments and it is important to assess these differences in order to develop our understanding of the role of Arctic tundra in the global carbon cycle. Although many previous studies have examined tundra carbon dioxide fluxes, few have concentrated on elevated terrain(hills and ridge tops) that is exposed to harsh environmental conditions resulting in sparse vegetation cover and seemingly low productivity. In this study we measured carbon dioxide(CO2) exchange of four common tundra communities on the crest of an esker located in the central Canadian low-Arctic. The objectives were to quantify and compare CO2 fluxes from these communities, investigate responses to environmental variables and qualitatively compare fluxes with those from similar communities growing in less harsh lowland tundra environments. Measurements made during July and August 2010 show there was little difference in net ecosystem exchange(NEE) and gross ecosystem production(GEP) among the three deciduous shrub communities, Arctous alpina, Betula glandulosa and Vaccinium uliginosum, with means ranging from -4.09 to -6.57 μmol·m^-2·s^-1 and -7.92 to -9.24 μmol·m^-2·s^-1, respectively. Empetrum nigrum communities had significantly smaller mean NEE and GEP(-1.74 and -4.08 μmol·m^-2·s^-1, respectively). Ecosystem respiration(ER) was similar for all communities(2.56 to 3.03 μmol·m^-2·s^-1), except the B. glandulosa community which had a larger mean flux(4.66 μmol·m^-2·s^-1). Overall, fluxes for these esker-top communities were near the upper range of fluxes reported for other tundra communities. ER was related to soil temperature in all of the communities. Only B. glandulosa GEP and ER showed sensitivity to a persistent decline in soil moisture throughout the study. These findings may have important implications for how esker tops would be treated in construction of regional carbon budgets and for predicting the impacts of climate change on Arctic tundra future carbon budgets.

High Vegetation of Lake Ayakagitma in Bukhara Region and Their Distribution

More than 500 lakes are found in Uzbekistan. Ayakagitma Lake is located on the border of the Northern Gijduvon and Shafirkon districts of Bukhara region. This lake was formed in 1985-1986 at the expense of the waters of the sewage dump collector. The area of the lake is 8200 hectares, the maximum depth is 35 m, on average 10 - 15 m, the minimum is 3 - 5 meters. The chemical composition of lake water is chloride-sulfate and has a calcareous character. 67 species of high plants belonging to 22 families were found in this area. 17 of these species are found in the water of the lake and 50 species are found around it. Of the most common species, Phragmites communis reach a height of 4.5 - 5.5 meters. Phragmites communis make up the total area of the lake 8 - 10 hectares.

Soil Characteristics Influence the Selection of Dominant Plant Genotypes Inhabiting Wadi Sudr, Egypt

Rangeland plant community and species composition are known to be related to specific soil properties. The current study investigated the ecological influence (soil characteristics) on the selection and distribution of ecological-related genotypes of dominant xerophyte species in WadiSudr of Egypt. AFLP analysis reflected the genetic profile of the samples species from two altitudinal ranges (up and midstream) and was compared statistically with the differences of their inhabiting soil characteristics on two depth levels (20 and 40 cm) using Mantel test. Correlation values (r) ranged from 0.585 - 0.778 when treating the physical and chemical properties of soil samples regardless its altitudinal area. The correlation confirms that the soil chemical and physical properties influence the selection of a certain genotypes of the dominant xerophytes plants collected from Wadi Sudr of Egypt to certain altitude, while depths at 20 and 40 cm play a key role in the early growth and then the colonization of the selected genotypes, respectively. More studies are needed to exactly test the role and the importance of each of the correlated property to the plant growth and colonization.

Transformation of vegetative cover on the Ustyurt Plateau of Central Asia as a consequence of the Aral Sea shrinkage

The gradual shrinkage of the Aral Sea has led to not only the degradation of the unique environments of the Aral Sea,but also numerous and fast developing succession processes in the neighborhood habitats surrounding the sea.In this study,we investigated the vegetative succession processes related to the Aral Sea shrinkage in the Eastern Cliff of the Ustyurt Plateau in Republic of Uzbekistan,Central Asia.We compared the results of our current investigation(2010–2017)on vegetative communities with the geobotany data collected during the 1970s(1970–1980).The results showed great changes in the mesophytic plant communities and habitat aridization as a result of the drop in the underground water level,which decreased atmospheric humidity and increased the salt content of the soil caused by the shrinkage of the Aral Sea.In the vegetative communities,we observed a decrease in the Margalef index(DMg),which had a positive correlation with the poly-dominance index(I-D).The main indications of the plant communities'transformation were the loss of the weak species,the appearance of new communities with low species diversity,the stabilization of the projective cover of former resistant communities,as well as the appearance of a new competitive species,which occupy new habitats.

Intrastorm stemflow variability of a xerophytic shrub within a water-limited arid desert ecosystem of northern China

An increasing number of studies in recent years has elucidated distinguishable effects of stemflow on hydrology and biogeochemistry within a variety of ecosystems.Nonetheless,no known studies have investigated the temporal variability of stemflow volume within discrete rainfall events for xerophytic shrubs.Here,stemflow was monitored at 5-min intervals using a tipping-bucket rain gage during the 2015 growing season for a xerophytic shrub(Caragana korshinskii)within a water-limited arid desert ecosystem of northern China.We characterized the stemflow temporal variability,along with rainfall,and found the temporal heterogeneity of rainfall clearly affected the timing of stemflow inputs into basal soil within discrete rainfall events.The rainfall threshold value for stemflow generation is not a constant value but a range(0.6~2.1 mm,with an average of 1.1 mm)across rainfall events and is closely associated with the antecedent dry period.Time lags existed between the onset of rainfall and the onset of stemflow,and between rainfall peaks and stemflow peaks.Our findings are expected to be helpful for an improved process-based understanding of the temporal stemflow yield of xerophytic shrubs within water-limited arid desert ecosystems.

Fatty Acid Composition of Seed Oil from Fremontodendron californicum

The fatty acid composition of the low water-use shrub Fremontodendron californicum was examined by high temperature capillary gas chromatography. The ground seeds were extracted by supercritical fluid extraction (SFE) to obtain the oil (25.6% w/w) and for subsequent determination of the fatty acid composition. There are five fatty acids present at 1.0% or greater with linoleic 71% of the total. Oleic, palmitic, stearic, vaccenic plus traces of palmitoleic and linolenic comprise the remainder. The fatty acid methyl ester composition would make the oil suitable for biodiesel production.

Water catchment with native species in the Brazilian Semiarid

Xerophyticplants are well adapted to the semiarid conditions because they have a high potential for the use of rainwater. They can store it in their roots (xylopodiums). The Amburanacearensis, commonly called Cumaru, native of the Brazilian semiarid, is very important because of its multiple-use: good quality wood, active food ingredient, perfume and medicine production. However, its management is practically unknown. Aiming to know more about this culture, an experiment was conducted to quantify the Cumaruwater needs, evaluate its water-use efficiency and the capacity of roots to store water. Five levels of water (0%, 25%, 50%, 75% and 100% of evapotranspiration) and five-plant spacing (0.20 × 0.20 m, 0.20 × 0.10 m, 0.20 × 0.05 m, 0.10 × 0.10 m and 0.05 × 0.05 m) were tested, and the results obtained analyzed statistically throughout F test. No influence of soil water level and plant spacing in the moisture content of the whole plant, in the aerial part or in the xylopodiums was observed. However, there was an effect of the treatments on the water stored in the whole plant in the aerial part or in the roots, per unit area. More than 80% of the water was stored in the roots. The crop growing with the smaller spacing without irrigation was shown to be quite efficient in using the rainwater, compared with traditional cultures irrigated.