基于"三生"空间优化的城乡交错区土地整治功能单元划定

为提升城乡交错区土地整治精细化管理水平,统筹发挥空间生产、生活、生态功能,开展土地整治功能单元划定研究。该文明确了土地整治功能单元内涵,以北京市海淀区为例,根据"明确功能区—确定评价单元—评价单元功能—确定功能单元"的划定思路,综合运用图层叠置法、区位商法、特尔斐法、多指标综合评价法和距离法,确定了5类整治功能,共计54个土地整治功能单元:1个农业生产提质增效类、3个产业园区节地类、28个乡村人居环境提升类单元集中分布在北部,17个城镇更新类单元集中分布在南部,5个山水林田湖综合整治类单元分散在中部和北部。通过单元划定指导整治工程有序推进,土地综合整治的空间优化功能可得到充分发挥:空间结构有效优化,农业生产空间将增加975 hm~2,3 061 hm~2乡村生活空间和308 hm~2城镇生活空间将得到改善,617 hm~2的集体产业园区将完成改造升级;空间发展质量得以保障,农田提高1.4个等级,农业规模化和产业化水平约提高3.7%,单位国内生产总值建设用地面积将年均降低8%。结果充分体现了海淀区"三生"空间优化的差异化需求,可为基于功能导向的土地综合整治差异化设计提供方法借鉴。     

The structure of urban and peri-urban gardens in Khartoum,Sudan

A verdant strip of urban and peri-urban agriculture (UPA) lines the banks of the River Nile at Khartoum (Sudan), but little is known about its physical structure and species composition. This study was conducted in 120 gardens, covering 160 ha at the urban locations of Tuti Island and Shambat and the peri-urban location of El Halfaya to determine the extent and plant composition of UPA gardens in Greater Khartoum, which includes the cities of Khartoum, Khartoum North and Omdurman. The survey identified 84 plant species from 35 plant families, of which 47 were utilised as crops predominantly for commercial production of fruits, vegetables, spices and condiments, grains, and fodder. The gardens of Tuti Island, where production of lime (Citrus aurantiifolia (L.) Swingle) was widespread, had a mean species richness of 1.7 and a Shannon index of 0.4. The gardens of Shambat, where leafy vegetables were common, had higher crop diversity levels with a mean species richness of 4.4 and a Shannon index of 1.2. The gardens of El Halfaya, which was the only location where the production of some spices and condiments was recorded, had a mean species richness of 3.7 and a Shannon index of 1.0. All three study locations were largely dominated by monocultural commercial production relying heavily on external inputs. The four groups of gardens distinguished by cluster analysis were cultivated by 21 ethnic groups, 46% of the surveyed households relied on additional off-farm income and gardens supplied 12% of household food. Economic and ecological benefits of the studied UPA gardens might be enhanced if crop diversity and structural complexity of these gardens were increased.     

Conservation of the dark-rumped petrel Pterodroma phaeopygia in the Galapagos Islands,Ecuador

The effects of predation and habitat deterioration produced by rats, cats, dogs, pigs, goats, burros and cattle, which have been introduced over the last two centuries to the Galapagos archipelago, have reduced the dark-rumped petrel Pterodroma phaeopygia population so that it is now in danger of extinction. By controlling rat numbers through poisoning, and by protecting the nesting colony from other predator and pest species through hunting, petrel breeding success in the Cerro Pajas colony, Floreana Island, has been increased. Preliminary studies indicate that immediate conservation efforts are also needed and are being initiated for at least two other petrel populations. Continued predator control is essential to halt further petrel population declines and to allow their numbers to recuperate.     

Surface water quality of factory-based and vegetable-based peri-urban areas in the Yangtze River Delta region,China

Detailed surveys of surface water in two contrasting peri-urban areas in the Yangtze River Delta region of China were conducted to determine the distribution of heavy metals, nitrogen (N) and phosphorus (P) as well as the speciation of N and P. A factory-based (FB) area was compared with a vegetable-based (VB) area during the dry season. The concentrations of heavy metals in the surface water in the FB area were higher than those in the VB area, suggesting modest contamination of surface water with Zn, Cu, Cr and Pb but not Cd, from discharge of factory effluent in the FB area but not the VB area. Although total N (TN) and total P (TP) levels in the surface water were high in both areas, the surface water in the VB area had significantly higher levels of nitrate N (NO₃–N), organic N (ON) and TN than those in the FB area. In both areas, the levels of water-soluble P (WP), organic P (OP) and TP were high in the river water that received municipal wastewater. The distribution of N and P species throughout the surface water system indicated that the NO₃–N and ON mainly came from vegetable fields, while ammonium N (NH₄–N), WP and OP were mainly from municipal wastewater. Treatment of municipal wastewater prior to discharge to reduce N and P by purification is recommended together with research and extension to develop more efficient use of N and P fertilizer by vegetable farmers.     

Assessment of the living and total biomass of microbial communities in the background chestnut soil and in the paleosols under burial mounds

The contents of phospholipids and carbon of the total microbial biomass were determined in the modern chestnut soil and in the paleosols buried under mounds of the Bronze and Early Iron Ages (5000–1800 years ago) in the dry steppe of the Lower Volga River basin. Judging from data on the ratio between the contents of phospholipids and organic carbon in the microbial cells, the carbon content of the living microbial biomass was calculated and compared with the total microbial biomass and total organic carbon in the studied soils. In the background chestnut soil, the content of phospholipids in the A1, B1, and B2 horizons amounted to 452, 205, and 189 nmol/g, respectively; in the paleosols, it was 28–130% of the present-day level. The maximum content was measured in the paleosols buried 5000 and 2000 years ago, in the periods with an increased humidity of the climate. In the background chestnut soil, the total microbial biomass was estimated at 5680 (the A1 horizon), 3380 (B1), and 4250 (B2) μg C/g; in the paleosols, it was by 2.5–7.0 times lower. In the upper horizons of the background soil, the portion of the living microbial biomass in the total biomass was much less than that in the paleosols under the burial mounds; it varied within 8.5–15.3% and 15–81%, respectively. The portion of living microbial biomass in the total organic carbon content of the background chestnut soil was about 4–8%. In the paleosols buried in the Early Iron Age (2000 and 1800 years ago), this value did not exceed 3–8%; in the paleosols of the Bronze Age (5000–4000 years ago), it reached 40% of the total organic carbon.     

工业型城乡交错区土壤重金属含量及其空间分异的特征-以无锡典型城乡交错区为例

Phosphorus （P） is necessary for growth and nitrogen fixation, and thus its deficiency is a major factor limiting legume production in most agricultural soils. The effect of phosphorus supply on nodule development and its role in soybeans （Glycine max L.） was studied in a nutrient solution. Plants were inoculated with Bradyrhizobium japonicum and grown for 35 days in a glasshouse at a day and night temperature of 25℃ and 15℃, respectively. Although increasing P supply increased the concentrations of P and N in the shoots and roots, the external P supply did not significantly affect the P concentration in the nodules, and the N fixed per unit nodule biomass decreased with increasing P supply. The nitrogen content in the shoots correlated well with the P content （r=0.92＊＊）. At an inoculation level of 10^2 cells mL^-1, the P supply did not affect the number of nodules; however, at inoculation levels of 10^3.5 and 10^5 cells mL^-1, increasing P supply increased both the number and size of nodules. Irrespective of the inoculation level, increasing P supply increased the nodule biomass relative to the biomass of the host plant. It is suggested that the P deficiency specifically inhibited the nodule development and thereby the total N2 fixation.     

Metabolic characteristics of microbial communities of Aeolian sandy soils induced by saline water drip irrigation in shelter forests

The microbial metabolic activities of soils sampled at eight depths (0–5, 5–15, 15–30, 30–50, 50–70, 70–100, 100–150 and 150–200 cm) in shelter forests (comprising the tree species, Haloxylon sp.) along the Tarim Desert Highway under drip irrigation with different saline waters were investigated by using Biolog technology. Variance analysis and principal component analysis were conducted. The average well colour development (AWCD) values for single carbon source use by microorganisms increased with the incubation time. The microorganisms reached a lag phase within 24 hours of incubation and entered exponential and stationary phases after 48 and 216 hours of incubation, respectively; however, the death phase was not obvious. As the salinity of drip irrigation water increased, the AWCD values significantly decreased; the AWCD value in the land drip‐irrigated with lowest saline water (S8) was roughly 20% larger than that of the land drip‐irrigated with highest saline water (S1), which was mainly caused by the differences in the use of carboxylic acids, amino acids and phenolic compounds by soil microorganisms. The vertical differences in carbon source utilization by soil microbial communities were obvious: these may be caused by the vertical differences in soil organism abundance associated with distribution of roots in the shelter forest. The largest and smallest AWCD values were noted in the 70–100‐cm soil layer and 0–5‐cm topsoil layer, respectively. The correlation coefficients between the AWCD values and soil organic matter, total nitrogen, total phosphorus, total potassium, available potassium, available phosphorus, pH, cation exchange capacity and bulk density were > 0.85. Thus, the differences in carbon source metabolism activities of soil microorganisms were caused mainly by the soil chemical properties, with total nutrients being the main driving factor. Furthermore, the amounts of carboxylic acids, amino acids and polymers provided sensitive markers for distinguishing the ability of soil microorganisms to use carbon sources under drip irrigation with different saline waters. Saline water irrigation affected the soil microbial community in shelter forest and produced obvious differences among the shelter forests irrigated with different saline waters.     

Fluvial Contamination Associated with Artisanal Gold Mining in the Ponce Enríquez,Portovelo-Zaruma and Nambija Areas,Ecuador

Artisanal gold mining in the Ponce Enríquez, Portovelo-Zaruma and Nambija areas of Ecuador has resulted in extensive contamination of the fluvial environment by mercury (Hg) andpotentially toxic ore-related elements including arsenic (As),cadmium (Cd), copper (Cu), lead (Pb) and zinc (Zn). Thisoccurs principally through the fluvial dispersion ofcontaminated mineral processing wastes and recycling of Hgsublimated during the burning of amalgam. Mercuryconcentrations in filtered (<0.45 μm) surface waters do notexceed the WHO Drinking Water Guideline value and the USEPAWater Quality Criteria for the Protection of Aquatic Life.Criteria for other potentially harmful elements are, however,exceeded by a wide margin in the Ponce Enríquez (As, Cu,Zn) and Portovelo-Zaruma (Cd, Cu, Zn) districts, but not inthe Nambija area. The Environment Canada sediment quality HgToxic Effect Threshold for the Protection of Aquatic Life isexceeded in all three mining areas. As, Cd and Cu in manysediment samples from the Ponce Enríquez and Portovelo-Zaruma districts exceed Sediment Toxic Effects Thresholds byfactors of 10 to >1000. The results highlight the need toensure that contaminated sediment and water do not entercommercial banana plantations and shrimp ponds downstream ofthe Ponce Enríquez mining district.     

餐厨垃圾堆肥对城郊菜田产量及氮利用的影响

为探讨餐厨垃圾堆肥对南方城郊菜田土壤氮素供应水平、叶菜类蔬菜产量及土壤残留和氮肥利用率的影响。以不施氮肥为对照(CK),在等氮量条件下,设置了传统化肥(NPK)、传统化肥+鸡粪(NPK+M)、餐厨好氧堆肥+化肥(NPK+FWA)、餐厨厌氧沼渣+化肥(NPK+FWD)4个处理,测定叶菜类蔬菜整个生育周期的土壤无机氮动态、产量、收获后剖面土壤氮素残留及表观氮素损失的变化。多茬试验结果表明:底肥施用后一周左右,NPK处理整体土壤无机氮供应水平高于NPK+M、NPK+FWA和NPK+FWD处理;追施氮肥后NPK+FWA处理土壤无机氮供应水平处于NPK和NPK+M两个处理之间,而NPK+FWD处理土壤无机氮略低于NPK和NPK+M处理;从总产量来看,NPK、NPK+M、NPK+FWA和NPK+FWD处理间无显著差异;而随着试验进行,与NPK+FWA和NPK+FWD处理相比,NPK和NPK+M处理产量明显增产20.1%～36.7%和17.8%～26.4%。从剖面土壤无机氮含量来看,餐厨垃圾堆肥部分替代化肥处理相比传统单施化肥和化肥配施鸡粪处理能够明显降低收获后表层土壤无机氮残留;从前四茬蔬菜总表观氮素损失来看,较高的氮肥投入带来了895.8～1041.2 kg/hm²的表观氮素损失量,各处理间无显著性差异;较高的氮肥投入及表观氮素损失导致小白菜季和空心菜季各处理当季氮肥利用效率分别仅有9.9%～16.7%和27.6%～37.6%。综上分析,在等氮量条件下,相比传统单施化肥和传统化肥配施鸡粪,餐厨垃圾堆肥氮替代30%化肥氮具有更好地协调土壤氮素供应和蔬菜作物吸收的作用,随着试验进行,餐厨垃圾堆肥部分替代化肥处理表现出增产趋势。但南方多雨地区餐厨垃圾堆肥还田具有较大的氮素损失风险,当季氮肥利用率偏低,今后需加强餐厨垃圾堆肥还田对土壤氮素综合损失的影响机制研究,并探索针对性的减排措施,为餐厨垃圾堆肥安全高效利用提供科学指导。     

Assessing the impacts of roads in peri-urban reserves: Road-based fatalities and road usage by wildlife in the Royal National Park, New South Wales, Australia

For protected reserves set aside for conservation, the impact of roads and traffic on wildlife can be severe, particularly for those in the peri-urban environment. Often reserves possess many sealed roads that have regular traffic from tourists and local residents. As managerial bodies struggle to control the wide variety of threats to the fauna within these reserves, the loss of life on roads only compounds the precarious nature of wildlife survival in these disturbed environments. As a first step to addressing this concern in Australia, this study quantifies the fatalities of wildlife killed on roads within the Royal National Park in New South Wales, and estimates those wildlife species using roadside habitat in order to identify species susceptible to collisions. Modelling of fatality data indicated that mammals were most likely to be killed where forage was abundant on the roadside verge and where there was plenty of protective cover, while birds were most likely to be killed when the height of roadside vegetation was low. A number of collision hotspots were identified along the surveyed road that should be the target of mitigation efforts. The average speed of vehicles travelling within the park peaked at night. This is of particular concern as activity by Australian mammals tends to be greatest at night. The findings indicate that roads in peri-urban reserves have the potential to alter the movement of animals and impact on their populations through loss of life.     

基于模糊逻辑的北京城市边缘区土壤重金属污染空间预测

Fuzzy classification combined with spatial prediction was used to assess the state of soil pollution in the peri-urban Beijing area. Total concentrations of As, Cr, Cd, Hg, and Pb were determined in 220 topsoil samples （0-20 cm） collected using a grid design in a study area of 2 600 kin2. Heavy metal concentrations were grouped into three classes according to the optimum number of classes and fuzziness exponent using the fuzzy comean （FCM） algorithm. Membership values were interpolated using ordinary kriging. The polluted soils of the study area induced by the measured heavy metals were concentrated in the northwest corner and eastern part, especially the southeastern part close to the urban zone, whereas the soils free of pollution were mainly distributed in the southwestern part. The soils with potential risk of heavy metal pollution were located in isolated spots mainly in the northern part and southeastern corner of the study region. The FCM algorithm combined with geostatistical techniques, as compared to conventional single geostatistical kriging methods, could produce a prediction with a quantitative uncertainty evaluation and higher reliability. Successful prediction of soil pollution achieved with FCM algorithm in this study indicated that fuzzy set theory had great potential for use in other areas of soil science.     

DRIS norms and limiting nutrients in banana cultivation in the South of Ecuador

Abstract

Foliar analysis is an effective method to diagnose the nutritional status of plants. However, the mineral concentration in foliar tissue has traditionally been evaluated by assessing the activity of each element, without considering the interactions between them. To address this, dual interactions were calculated using the Diagnosis and Recommendation Integrated System (DRIS) to identify which crop nutrients are most influential in nutrient imbalances and which are the most limiting nutrients for the nutritional status of banana crops in Ecuador. To achieve this, a regional survey of the nutritional status and its productivity levels was conducted for 188 different sites during the crop season in 2017–2018, involving banana cultivars ‘Vallery’ and ‘Williams’, from the Cavendish subgroup. The DRIS calculation method was combined with Beaufils and Jones functions. From the initial 188 foliar samples, 83 samples (representing 44% of the population) were considered to represent the high-yield reference population, with yields of 38–60 t ha^?1. The DRIS method defined the mean nutritional balance index, which was not found to be statistically correlated (p?>?0.05) with productivity, revealing that there was no significant association with the nutritional status of the plants. Specific DRIS norms were obtained and indicated that deficiencies in K, N, Ca, and Fe, and excesses in Mn, B, Cl, Zn, S, Cu, and Mg were the most limiting nutrients for banana cultivars in the south of Ecuador.     

Earthworm communities of flooded grasslands in Matsalu,Estonia

Earthworm communities in the soil of flooded (coastal and floodplain grasslands) and non-flooded (boreo-nemoral) meadows were studied. The average number of species in coastal and floodplain meadows was low, earthworm communities of boreo-nemoral meadows were diverse and the average number of species was high. Specific composition of earthworm communities varied between the three types of meadows. Earthworm communities of flooded meadows possess specific characteristics being low in both numbers and species due to periodical anaerobic conditions during over flooding and negative effect of sea water in coastal meadows.     

中国腾格里沙漠生物土壤结皮中的可培养微真菌群落

Biological soil crusts are essential components of arid ecosystems. We examined the variations in microfungal communities inhabiting different biological crust types in the vicinity of the Shapotou Research Station in the Tengger Desert, China. A total of 134 species from 66 genera were isolated using the soil dilution plate method. The mycobiota of the crusts from the Tengger Desert, similar to that of the Negev Desert in Israel, was dominated by melanin-containing species with large multicellular spores. Abundance of these xeric species increased spatially with increasing xeric conditions from moss-dominated to cyanobacterial crusts. Density of microfungal isolates displayed the opposite trend and was positively correlated with chlorophyll content, indicating the possible significant influence of organic matter content and wetness duration on fungal biomass. Within a chronosequence of the localities of different periods after sand stabilization with revegetation, little variations were revealed in species composition and isolate density of the crust microfungal communities, while a tendency towards a decrease in the community diversity level with the crust age was noted. Microfungal communities from stabilized localities differed from those of the natural localities in abundance of the dominant and some frequent species, and in the fluctuations of diversity characteristics between the cyanobacterial and moss-dominated crusts. The variations in mycobiotic parameters in the soil crusts of the Tengger Desert were apparently associated with the topographically induced variations in abiotic conditions, while the differences in microfungal community of soil crusts between the Tengger and Negev deserts, such as the significantly higher abundance of thermotolerant species in the crusts of the Tengger Deserts, were caused by the principal differences in their precipitation regimes, associated with different rainy seasons, winter and summer in the Negev and Tengger deserts, respectively.     

Archaeal communities in the sediments of different mangrove stands at Dongzhaigang,China

Purpose

Knowledge of archaeal communities is essential for understanding of the mechanism of carbon and nitrogen cycle in the mangrove sediment ecosystem. Presently, little is known about archaeal communities in the Dongzhaigang mangrove sediments. This study aimed to characterize the archaeal communities in sediments of different mangrove stands and to find out the correlations between archaeal communities and the environmental factors of sediments.

Materials and methods

Sediment samples were collected from the Dongzhaigang mangrove forest for analysis of soil properties and archaeal communities, by national standard methods and Illumina Miseq archaeal 16S ribosomal RNA (rRNA) gene sequencing, respectively.

Results and discussion

The archaeal community in the Dongzhaigang mangrove forest was constituted by some phyla from “TACK” and “DPANN” supergroups, and dominated by Euryarchaeota. Among sediments of the four mangroves in Dongzhaigang, principal coordinates analysis (PCoA) scatter plot showed a trend of difference in the archaeal community structure in the Bruguiera gymnoihiza and Kandelia candel stands from that in the Laguncularia racemosa and Sonneratia apetala stands. The abundance of the order Methanosarcinales was the highest in the sediments of K. candel mangroves, whereas the order of Methanobacteriales dominated in B. gymnoihiza sediments. The highest richness and diversity values of Archaea occurred in K. candel sediments, while the lowest in B. gymnoihiza. Pearson correlation showed the significant relationships between sediment properties and some dominant genera, with a positive and significant correlation between sediment properties and genus Methanobacterium, coinciding with the maximum values of sediment properties and abundance of Methanobacterium in the sediment of B. gymnoihiza. Such results indicated that the difference of archaeal community structure among mangrove sediments may be caused by the different sediment characteristics. Methanogenic communities in the Dongzhaigang mangrove forest sediments were, at the order level, constituted by Methanobacteriales, Methanomicrobiales, Methanosarcinales, and Methanomassiliicoccales.

Conclusions

The investigation indicated that the Dongzhaigang mangrove sediment ecosystems support diverse archaeal communities and methanogenic communities, and that there was a general trend of difference in the archaeal community structure in the B. gymnoihiza and K. candel mangrove sediments from that in the L. racemosa and S. apetala sediments. Such difference may be caused by the difference in sediment characteristics.

     

Nitrogen,a major limitation in the productivity of natural communities,crops and pastures in the pacific area

Various aspects of the nitrogen cycle are reviewed as a background for discussion of nitrogen balance and economy in plant communities. Even though fixation of atmospheric nitrogen generally exceeds losses of nitrogen from the biosphere it is pointed out that plants extract nitrogen from the soil faster than it can be mineralized from organic forms. This difference in rates leads to a nitrogen deficiency in plants, particularly in high yielding crop plants, and subsequently a protein deficiency in animals.Some facets of legume bacteriology are discussed also. In particular the introduction of legumes to new areas and the need for inoculation of seed with specific Rhizobium strains, importance of strain selection, testing and supply, legume inoculant quality and seed inoculation and pelleting.     

Bacterial communities are more dependent on soil type than fertilizer type, but the reverse is true for fungal communities

The soil microbial community is strongly influenced by a wide variety of factors, such as soil characteristics and field management systems. In order to use biological indicators based on microbial community structure, it is very important to know whether or not these factors can be controlled. The present study aimed to determine whether soil type or fertilization has a greater influence on the soil microbial community based on denaturing gradient gel electrophoresis (DGGE) analysis of 12 experimental field plots containing four different soil types, Cumulic Andosol, Low-humic Andosol, Yellow Soil and Gray Lowland Soil, kept under three different fertilizer management systems since 2001 (the application of chemical fertilizer, the application of rice husk and cow manure, and the application of pig manure). Bacterial DGGE analysis using 16S rRNA genes and fungal DGGE analysis using 18S rRNA genes revealed that the bacterial community was related to the soil type more than the fertilization; however, the fungal community was related to the fertilization more than the soil type. These results might suggest that the fungal community is easier to control by fertilization than the bacterial community. Thus, we propose that indicators based on the fungal community might be more suitable as microbial indicators for soil quality.