The impact of grazing on seedling patterns in degraded sparse‐elm grassland

Over‐grazing by livestock in semi‐arid ecosystems is one of the main causes of desertification. Although over‐grazing presents a global environmental challenge, only a few studies have investigated grazing impacts on the composition of species and functional groups of seedling bank. In this study, we determined whether the composition of seedling species and functional groups, as well as the correlations between the seedlings of sparse‐elm (Ulmus pumila var. sabulosa or U. pumila) and other species changed under three grazing intensities in the degraded sparse‐elm grassland in the Horqin Sandy Land, China. Species composition and abundance of established seedlings were surveyed and the relationships between seedlings of U. pumila and other species were analyzed. The results showed that plant communities under moderate grazing were more stable than the other two grazing intensities due to higher seedling density, higher species richness and higher number of perennial herbs. Seedlings of U. pumila could even prevent noxious seedlings growth under moderate grazing. We concluded that moderate grazing could benefit the recovery of this sparse‐elm grassland in the Horqin Sandy Land

Sand dune stabilization changes the vegetation characteristics and soil seed bank and their correlations with environmental factors

Currently the amount of data available on the effect of sand dune stabilization on species conservation in inter-dune lowland is very limited, especially for the sand dune systems in semi-arid regions. In this study, we determined whether the characteristics of above-ground vegetation, soil seed bank and their relationships with environmental factors changed with sand dune stabilization in the inter-dune lowlands in Horqin Sandy Land, China. Species composition, abundance and coverage of aboveground vegetation as well as soil seed bank composition and density were surveyed and their correlations with environmental factors (pH, organic matter content, total nitrogen and total phosphorus) were determined. The results showed that changes in the relationship between aboveground vegetation, soil seed bank and soil quality followed the changes in aboveground vegetation and soil seed banks. Aboveground vegetation species richness increased with sand dune stabilization, but soil seed bank species richness declined. The inter-dune lowland of active sand dunes could provide specific habitats for some endemic species and pioneer psammophyte species as indicated by data on aboveground vegetation and soil seed bank. Our results suggested that both active and stabilized sand dunes should be maintained since active sand dunes are essential for the survival of endemic or pioneer species and stabilized sand dunes are important for sustaining species richness

Somaclonal tolerance of sugarcane to salinity on different concentrations of sea water

In vitro somaclonal variation becomes one most promising breeding method to bear new\ud variety tolerant to environmental stress, while other in vitro method is still in initial stage,\ud such as protoplasm fusion or DNA recombinant. This research was carried out at\ud Experimental Farm of Faculty of Agriculture, Hasanuddin University from March to\ud September 2007. Field experiment was set up in a 2-factor randomized complete block\ud design. First factor was sugarcane clone, consisted of 12 clones, second one was sea water\ud concentration, i.e. 0% (EC=0.11 mmhos cm-1), 35% (EC=15.13 mmhos cm-1) and 70%\ud (EC=24.50 mmhos cm-1) of sea water. Experiment???s results revealed that there was\ud interaction between sugarcane clone and sea water concentration, as shown on stem\ud diameter, photosynthesis rate, transpiration rate, stomatal conductance and relative content\ud of leaf water. Clonal difference appeared on 35% sea water. Higher concentration caused\ud clonal salinity tolerance to decrease. R579 clone derived from callus was able to grow at\ud NaCl concentrations of 0 and 8 g L-1, Q81 at 4 g L-1, PS91 at 0, 4 and 8 g L-1. These three\ud clones were clone tolerant to salinity. Limit of salinity tolerance of sugarcane was reached at\ud 70% sea water, which was recommended as tolerance limit of sugarcane clone to salinity

Comparative Study on Soil Infiltration Characteristics of Different Land Use Types in Horqin Sandy Land

[Objective] The differences in water infiltration characteristics between different land use types in Horqin sandy land were determined in order to provide a scientific reference for the study of water and material transport in the vadose zone in arid and semi-arid regions. [Methods] Soil infiltration and its influencing factors for eight typical land use types (Pinus sylvestris plantation, Caragana korshinsk plantation, Caragana microphylla plantation, abandoned grassland, meadow grassland, sparse forest grassland, corn field, and bare sandy land) in Horqin sandy land were measured in the field using a double ring infiltration apparatus and a laboratory analysis of soil physical properties. At the same time, the Kastiakov model, the Horton model, the Philip model, and the G-P comprehensive model were used to simulate the water infiltration process, and goodness of fit values for the models were compared. [Results] ① There were significant differences in soil infiltration characteristics among different land use types. The initial infiltration rates ranged from 1.595 mm/min to 12.020 mm/min, and followed the order of bare sandy land>Caragana korshinskii plantation>corn field > Pinus sylvestris plantation>Caragana microphylla plantation>meadow grassland>abandoned grassland>sparse forest grassland. The infiltration rate at 15 min varied from 0.617 mm/min to 3.690 mm/min, and followed the order of bare sandy land>Caragana korshinskii plantation>Pinus sylvestris plantation>Caragana microphylla plantation>corn field>abandoned grassland>meadow grassland>sparse forest grassland. The saturated infiltration rate varied from 0.576 mm/min to 3.495 mm/min, and followed the order of bare sandy land>Caragana korshinskii plantation>corn field>Caragana microphylla plantation>Pinus sylvestris plantation>abandoned grassland>meadow grassland>sparse forest grassland. ② The infiltration rate of different land use types was negatively correlated with soil bulk density and fine sand content, and positively correlated with medium sand content. Stable infiltration rate was positively correlated with non-capillary porosity. ③ The goodness of fit values for the models to estimate soil infiltration in Horqin sandy land followed the order of Horton model>G-P comprehensive model>Kastiakov model>Philip model. The Horton model had the highest coefficient of determination and the smallest relative error, and could accurately reflect the actual situation of soil infiltration in Horqin sandy land. [Conclusion] The characteristics of soil infiltration were different among different land use types in Horqin sandy land. The Horton model had high fitting ability in Horqin sandy land, and can, therefore, be used to estimate water infiltration

The feasibility of using soil seed bank for natural regeneration of degraded sandy grasslands

Desertification in degraded grasslands is manifested through the development of bare sandy patches, which eventually lead to habitat fragmentation. The ability of these bare sandy patches to regenerate naturally through in-situ soil seed banks is not well understood. To fill this knowledge gap, we randomly selected 24 bare sandy patches with areas ranging from 19 to 898 m2 in a desertified grassland of the Horqin sandy land, Northern China to determine whether soil seed bank can be used for natural regeneration of bare sandy patches. Species composition and density of soil seed bank as well as aboveground vegetation composition, abundance and coverage were investigated. We then determined their relationships with in-situ habitat characteristics. Our observations showed that the studied area had low soil seed bank density and species richness, as well as depauperate soil seed bank communities. Consequently, local soil seed bank was not able to provide sufficient seed source for natural regeneration. This was indicated by the relationships between aboveground vegetation, soil seed bank and the in-situ habitat characteristics. For bare patches with an area between 300 m2 and 900 m2, increase the soil seed bank density and species richness should be the main restoration measures. For bare patches with a small area of less than 50 m2, restoration of vegetation density should be the main measure. Our data highlighted that different extents of desertification, indicated by different bare patches, are requiring distinct restoration measures

Synthesis, crystal structure and Hirshfeld surface analysis of 5,5-di­phenyl-2-[2-(propan-2-yl­­idene)hydrazin-1-yl]-4,5-di­hydro-1H-imidazol-4-one N,N-di­methyl­formamide hemisolvate

The asymmetric unit of the title structure, 2C18H18N4O2·C3H7NO, consists of two independent mol-ecules of the substituted imidazolone having different conformations, and one mol-ecule of solvent DMF. The two imidazolone mol-ecules are linked by N-H⋯N and C-H⋯O hydrogen bonds and the DMF is joined to one of these by an N-H⋯O hydrogen bond. Additional N-H⋯N and C-H⋯O hydrogen bonds link these groups into corrugated layers parallel to the (101) plane with the layers joined by C-H⋯π (ring) inter-actions. A Hirshfeld surface analysis indicated that H⋯H inter-actions account for over half of the inter-molecular contacts

Geographical distribution and determining factors of different invasive ranks of alien species across China

Determination of the geographical distribution and life-form spectra of alien species with different invasive abilities are essential to understand the process of invasion and to develop measures to manage alien species. Based on six classifications of Chinese alien species, environmental and social data, we determined species density, life-form spectrum of alien species, and the relationship between species density of alien species and climatic or social factors. The species density of alien species increased from the northwest to the southeast regions of China for all the six ranks. The boundary line between low and high species density of alien species was consistent with the dividing line of population density (the “Hu Line”). Mean annual precipitation was the most important factor for species density in malignant invaders, serious invaders, local invaders, and species requiring further observation (Ranks I, II, III, and V, respectively). Gross domestic product per square kilometer and annual minimum temperature were the most important factors in mild invaders and cultivated aliens (Ranks IV and VI, respectively). Annual and biennial herbs made up 52.9% to 71.2% of total species in Ranks I to IV; shrubs and trees 3.7% to 14.7%. The annual and biennial herbs were 35.5% and 32.6%, and the shrubs and trees were 25.3% and 31.6% in Ranks IV and VI. Results implied that precipitation was the most important factor on species density for the invasive alien species. However, social factors and temperature were the most important factors for the non-invasive alien species. The invasive alien species had a high proportion of annual and biennial herbs and non-invasive alien had a high proportion of shrubs and trees. It is important to understand the geographical distribution and life-form spectra of various invasive alien species for alien species controls

2-Chloro-N-(4-hydroxyphenyl)acetamide

The title compound, C8H8ClNO2, is significantly distorted from planarity, with a twist angle between the planes through the hy­droxy­benzene and acetamide groups being 23.5 (2)°. This conformation is supported by intra­molecular C—H⋯O and N—H⋯Cl contacts. In the crystal, N—H⋯O hydrogen-bonding contacts between acetamide groups and O—H⋯O contacts between hydroxyl groups form tapes propagating parallel to [103]