66 research outputs found
The Change of Karez and its Cause in Turpan Basin, China
No full textKarez is originated from two thousands years ago in Turpan Basin and has played a decisive role in locally socio-economic development Surface water and electric pumped well, change of karez and its causes in Turpan Basin are analyzed in this paper Results indicated that (1) change of karezes could be divided into two stages in this basin over the last 55 years, the dramatic increase stage (1949-1966) when the karez's number, output, flow and irrigating farmland area all dramatically increased due to the rapid increase of population and farmland area, and the abandonment stage (1966-2003) when karez's flow and output gradually declined, and many karezes dried up and dis-used (2) karezes were abandoned due to irrational exploitation and utilization of surface water lead to declining of supply water of karez, unlimitedly bind increasing electric pumped wells and its irrational layout lead to decreasing of groundwater level, and some disadvantages of karez also should be responsible for its abandonment (3) The abandonment of karez systems causes migration of residents in some villages, decrease of irrigated areas and natural vegetation areas, and increase of drought and wind disaster
The karez of the Sauran region of Central Asia
No full textA large number of lines of water collection wells were identified by aerial surveys in the arid region near the ancient city of Sauran on the Middle Syr Darya (South Kazakhstan, Central Asia). They are locally called karez, which in Persian means water uplift. Initially these were assumed to be qanat, a water collection and distribution system that is widespread in the Middle East, North Africa and Central Asia. Recent surveys discovered more than 100 km of such lines in the Sauran area. The most surprising discovery was that there was no evidence of galleries that might have collapsed due to poor construction or maintenance. The excavations of a series of these wells are described and a new model for water transport and delivery is proposed that takes advantage of the local hydrogeology. The study has historical significance for the reconstruction of water and land use in the Turkestan oasis during the last 2000 years; and the rediscovery of this forgotten technique could have economic significance for modern land reclamation in desert zones
Time series of environmental parameters of habitats along the Schleswig-Holstein Baltic Sea (2018 et seq)
No full textThe here presented data time-series are connected to the publication "Environmental parameters of shallow water habitats in the SW Baltic Sea" (Franz, M. et al. 2019b). Since 2019 a number of stations were added, and, hence, new time-series started. Every year a new dataset will be published including both, old and new stations. The following abstract is revised from Franz, M. et al. (2019b): The coastal areas of the Baltic Sea represent highly variable environments. In order to record the environmental conditions in shallow water habitats of the SW Baltic Sea, a monitoring program was established. The monitoring sites are located along the Baltic Sea coast of Schleswig-Holstein, Germany. Along the coast, 23 stations were established, where samplings for dissolved inorganic nutrient concentrations are conducted. Here, twice per month, water samples are collected in a water depth of 0.5 m. The samples are analysed for the concentration of dissolved inorganic nutrients (total oxidized nitrogen, nitrite, ammonia, phosphate and silicate) by UV/VIS spectroscopy using a continuous flow analyser (type QuAAtro 30; comp. SEAL Analytical, Hamburg, Germany. The system is equipped with a SEAL XY-2 autosampler). Quality control for nutrient measurements is ensured by certified reference material (CRM) by KANSO TECHNOS CO, LTD, Osaka, Japan. Additionally, at four shallow water stations (Booknis Eck, Bülk, Behrensdorf and Katharinenhof) temperature, salinity and dissolved oxygen are continuously logged at 2-3 m depth by self-contained data loggers. These are: (I) MiniDOT loggers (Precision Measurement Engineering; http://pme.com; ±10 µmol L-1 or ±5 % saturation) including antifouling copper option (copper plate and mesh) to measure dissolved oxygen concentration and (II) DST CT salinity & temperature loggers (Star-Oddi; http://star-oddi.com; ±1.5 mS cm-1) to record the conductivity. Both sensor types additionally record water temperature with an accuracy of ± 0.1 °C. The sampling interval was set to 30 minutes for all parameters. Another seven stations for continuous recordings of environmental parameters (again: temperature, salinity, dissolved oxygen) with the same two types of sensors were installed at 4-6 m depth in the context to the long-term monitoring project RegLocDiv (Regional-Local-Diversity) by M. Wahl (Franz, M. et al. 2019a) and included into this data set. These stations are at: Falshoeft, Booknis Eck, Schoenberg, Westermakesdorf, Staberhuk, Kellenhusen and Salzhaff (abandoned in 2023). Since 2021, in the context of implementing a reef monitoring to fulfil obligations by the EU Habitats Directive, step-by-step, eleven further stations were installed at reefs in the Schleswig-Holstein Baltic Sea. These are at: Platengrund (14 m depth) and Mittelgrund (8 m) (both since 2021), at Walkyriengrund (9 m), Brodtener Ufer (8 m), Außenschlei (11 m), Kalkgrund (8 m), Stollergrund (7.5 m) and Flueggesand (10 m) (all since 2022), as well as at Gabelsflach (10 m), Sagasbank (8.5 m) and Stabehuk (11.5 m) (all since 2023). Again, at all of these 11 stations, temperature, salinity and dissolved oxygen are continuously logged by self-contained data loggers: Conductivity (and temperature) is logged by HOBO® Salt Water Conductivity/Salinity Data Logger (Onset Computer Corporation, Bourne, MA, USA; https://www.onsetcomp.com) using the U2X protective housing to prevent fouling on the sensors. The same MiniDOT loggers (Precision Measurement Engineering) as at the above mentioned more shallow stations (including antifouling copper plate and mesh) are used to measure dissolved oxygen concentration. Dissolved oxygen concentration data measured by the MiniDOT loggers are corrected for a depth of 5 m (or 2,5 m on the shallow stations) using the software provided by the manufacturer. Additionally, a manual compensation for salinity was calculated (see details in Franz, M. et al. 2019b). Quality control was carried out by spike and gradient tests, following recommendations of SeaDataNet quality control procedures (see https://seadatanet.org/Standards/Data-Quality-Control). All data values were flagged according to applied quality checks using the following flags: 1 = Pass, 2 = Suspect, 3 = Fail, 4 = Visually suspect, 5 = Salinity compensation fail (further explanations can be found in Franz, M. et al. 2019b). The project is funded by the LfU (Landesamt für Umwelt, Schleswig-Holstein, Germany). Main responsible persons are C. Hiebenthal, C. Lieberum, F. Weinberger and R. Karez. Responsible for the nutrient analysis: N. Stärck; Responsible for taking the water samples: C. Lieberum and D. Bürger
Locally managed irrigation systems: Essential tasks and implications for assistance, management transfer and turnover programs
No full textIrrigation managementIrrigation systemsIrrigation schedulingPrivatizationFarmer participationWater managementWater rightsWater allocationResource managementOrganizational dynamicsConflictCommunicationTraining
Competition, coexistence and diversity on rocky shores
No full textThe question "Why are there so many species?" has puzzled ecologist for a long time. Initially, an academic question, it has gained practical interest by the recent awareness of global biodiversity loss. Species diversity in local ecosystems has always been discussed in relation to the problem of competi tive exclusion and the apparent contradiction between the competitive exclu sion principle and the overwhelming richness of species found in nature. Competition as a mechanism structuring ecological communities has never been uncontroversial. Not only its importance but even its existence have been debated. On the one extreme, some ecologists have taken competi tion for granted and have used it as an explanation by default if the distribu tion of a species was more restricted than could be explained by physiology and dispersal history. For decades, competition has been a core mechanism behind popular concepts like ecological niche, succession, limiting similarity, and character displacement, among others. For some, competition has almost become synonymous with the Darwinian "struggle for existence", although simple plausibility should tell us that organisms have to struggle against much more than competitors, e.g. predators, parasites, pathogens, and envi ronmental harshness
Allium caroli-henrici Wendelbo 1968
No full textAllium caroli-henrici Wendelbo (Bot. Not. 121: 274, 1968) Figs. 7-11, 17 Bulbs 3 cm long, 1.5-2.2 cm in diameter, globose, with coriaceous, blackish to dark brown, longitudinally split outer tunics; inner tunics thin, pale to light brown. Scape purplish, 8-12 cm erect to slightly flexuose, (subterranean scape 4-4.5 cm). Leaves 1-3, opposite, as long as scape or longer, 3.5-9 mm wide, linear, margin minutely scabrid. Spathe 0.5-1.5 cm long, four-lobed, membranous with purple nerves. Umbel hemispherical, dense; with unequal, 1.5-3 cm long, cylindrical, thin pedicels. Perigonum campanulate; tepals mauve with dark to brownish flush paler at base (purple at tip and yellowish at base when dry), nerve purplish, unequal 7- 10 mm long, obtuse, margins entire, outer tepals elliptic, inner tepals ovate. Filaments nearly half the length of tepals (inner filament slightly longer), 3.5-5.5 mm long, inner filaments subulate broader at base, outer filaments suboblong, filaments connate at base and adnate to tepals. Anthers 2 mm, oblong, dorsifixed, yellow. Ovary ovoid to cylindrical, angular, green, style 2- 3 mm, stigma lobed, mature capsule brownish, triangular obcordate. Seeds black, irregularly shaped, rough, up to 2.5 mm. Vernacular name: Sur Khatol Distribution: Previously only reported as endemic from SW and C. Afghanistan in the provinces Farah, Daykundi and Urozgan (Wendelbo, 1971; Breckle et al., 2013). Newly found in Pakistan in Qamardin Karez west of Zhob district along the border with Afghanistan. A very rare species in our area. Ecology: Found in red clay loam soils. Ethnobotany: The bulb is edible. Specimens examined: Balochistan, Zhob district, Qamardin Karez, Tahir Khan, 16 May, 2019 (RAW100808). This species also belongs to A. subg. Melanocrommyum sect. Thaumasioprason.Published as part of Khan, Nazar, Fritsch, R. M., Sultan, Amir & Khan, Tahir, 2021, ALLIUM (AMARYLLIDACEAE) SPECIES IN PAKISTAN: TWO NEW RECORDS AND A NEW SPECIES FROM ZHOB (BALOCHISTAN), pp. 1-7 in Pakistan Journal of Botany 53 (5) on page 2, DOI: 10.30848/PJB2021-5(1), http://zenodo.org/record/467987
Sediment patch selectivity in tropical sea cucumbers (Holothurioidea: Aspidochirotida) analysed with multiple choice experiments
No full textTo investigate patch selectivity in aspidochirotide holothurians, individuals of five species (Holothuria (Halodeima) atra Jäger, H. (H.) edulis Lesson, H. (Microthele) nobilis Selenka, Stichopus chloronotus Brandt and S. variegatus Semper) were subjected to multiple choice experiments. As a food source, sediments were pre-cultivated in petri dishes under different light and nutrient regimes. This resulted in four sediment treatments with different levels of microalgal biomass (measured as chlorophyll a and phaeophytin concentrations). Only two sediment treatments were used for experiments with H. nobilis and S. variegatus. The sediments were offered simultaneously to individual holothurians (six per experiment), and the weights of the sediment in each petri dish at the start and after 48 h were used to calculate a selection index together with confidence intervals for each food type. In experiments with H. atra and H. edulis, the animals exhibited no preference for any food type. In contrast, S. chloronotus significantly selected sediments with the highest contents of microalgae and avoided the sediment with the lowest pigment concentrations. These results were supported by field collections of sediments found directly underneath holothurians. Sediment underneath H. edulis did not differ from the average sediment of the habitat, while H. atra was found on sediments only slightly higher in chlorophyll a. Chlorophyll a concentrations underneath S. chloronotus were distinctly higher than in the adjacent sediment and that underneath H. atra. H. nobilis showed only a weak preference for sediments with higher pigment concentrations in aquarium experiments, and no patch selectivity in this species was found in the field. Stichopus variegatus exhibited a very distinct patch selectivity towards sediments with more nutritional value in both aquaria experiments and field measurements. Thus members of the genus Holothuria had no, or only a weak, tendency to select their food source, whereas both Stichopus species appeared to carefully select the sediment patch to feed on
Allium zhobicum Nazar Khan, Amir Sultan & R. M. Fritsch 2021, species nova
No full textAllium zhobicum Nazar Khan, Amir Sultan & R.M. Fritsch, species nova. Figs. 1-6, 17 Type: Balochistan, Zhob district, Qamardin Karez, Khutkandai, 31°31’31”N 68°14’38”E, Nazar Khan Mandokhel, 24 April, 2020 (RAW101342). Diagnosis: The shape of ovary is most similar to A. mirum Wendelbo, but this species has papery outer bulb tunics and up to 8cm broad, elliptical leaves, a campanulate perigonium, up to 3 cm long pedicels, and longer obovate tepals of brown purple colour. The violet upper parts of filaments are similar to those of A. hindukuschense Kamelin & Seisums, but A. zhobicum differs from A. hindukuschense by much broader and scarcely recurved tepals of lilac colour and with rounded apices, and spherical ovaries. Description: Bulbs 1.5-2.5 cm in diameter, globose; outer tunics initially light brown, delicate and fragile but coriaceous and brown when dry; inner tunics membranous, white. Scape 10-30 cm long, cylindrical, glabrous, green to yellowish green. Leaves 1-3, longer than scape, linear, 5-10 (18) mm broad, margins entire towards apex and papillate towards base. Spathe membranous, up to 1 cm with brownish nerves, splitting into 3 lobes longitudinally to obliquely. Umbel hemispherical, dense. Pedicels unequal, 10-20 mm long, green to purple. Perigonium stellate, tepals whitish lilac to lilac with violet to purple nerve, 6-7 mm long and 1.5-1.8 mm broad, elliptical-linear to oblong, recurved, obtuse to acute, outer tepals broader at base than inner ones. Filaments narrow triangular, at base connate and adnate to tepals, shorter to slightly longer than tepals, violet at apex becoming creamy toward base; inner filaments slightly broader at base than outer ones. Anthers 1-2 mm, violet to brownish, dorsifixed. Ovary green, six lobed depressed-globose; style 3-6 mm, filiform, exserted; stigma violet. Capsule triangular, greenish white, olive green at angle; seeds black, 2-3 mm long, irregularly shaped to ovate and D-shaped. Plants growing on sandy clay to sandy loamy soil near Chukhan have longer scapes, larger leaves, and lax flowers with pinkish-lilac tepals. Vernacular name: Khatol. Etymology: The species is named after the Zhob district. Distribution: Found in several localities in Zhob district (Chukhan, Larai, Khutkandai, Qamardin Karez) along the border to Afghanistan. Ecology: Usually found growing in sandy loam. Ethnobotany: The whole plant is edible. Especially the bulbs are collected in large amounts by the local population and are eaten raw. The species might become threatened by over-collecting in the future. The flowers are also eaten by goats and sheep. Additional specimens examined: Balochistan, Zhob district, Chukan, 31°15’39”N 68°52’40”E, 2017 m asl, Nazar Khan Mandokhel, 23 April, 2020 (RAW 101348). The new species belongs to A. subg. Melanocrommyum (Webb & Berthel.) Rouy sect. Thaumasioprason Wendelbo.Published as part of Khan, Nazar, Fritsch, R. M., Sultan, Amir & Khan, Tahir, 2021, ALLIUM (AMARYLLIDACEAE) SPECIES IN PAKISTAN: TWO NEW RECORDS AND A NEW SPECIES FROM ZHOB (BALOCHISTAN), pp. 1-7 in Pakistan Journal of Botany 53 (5) on pages 1-2, DOI: 10.30848/PJB2021-5(1), http://zenodo.org/record/467987
- …
