Endangered plant life

This paper discusses ways and means of more effective action, on an international scale, for the protection of endangered plant life, and shows how, in places where people have become aware of possessing spectacular or unique examples of plant life, they have often added to amenities around sacred places and created inviolate parts of the world's heritage. Good results for conservation of representative areas have been reached locally through improved attitudes towards rational land-use planning, great caution in the employment of herbicides and pesticides, recognition in forestry of the need for a systems planning for natural areas, and awareness that the great diversity of the green plant cover, of flowers and trees, is among the most delightful features helping to keep the Earth as a livable and beautiful environment. Plant protection can be a very good and profitable way to promote local tourism.     

Diversity and plant growth promoting evaluation abilities of bacteria isolated from sugarcane cultivated in the South of Brazil

Plant growth promoting (PGP) bacteria associated with sugarcane are a promising alternative for the expansion of this crop in Southern Brazil. In this study bacterial strains from different sugarcane fields were isolated to estimate their diversity, to evaluate some of their PGP activities and to use them as inoculant strains in field experiment. Samples of rhizospheric soil, roots, and stems of sugarcane were collected in six Rio Grande do Sul localities. The isolation of bacteria was made in three different N-free media. DNA from each isolate was subjected to nifH or 16S rDNA PCR-RFLP, and to the 16S rDNA partial sequencing. Five hundred and sixteen strains were isolated and several PGP characteristics were analyzed. Shannon index was used to evaluate the bacterial diversity. Indexes varying from 0.94 to 2.46 were obtained. Soil pH and clay were the characteristics most closely related to bacterial diversity. Achromobacter, Agrobacterium, Burkholderia, Gluconacetobacter, and Stenotrophomonas were the most abundant genera. Concerning the PGP activities, indolic compounds production was detected in 368 isolates; 138 isolates were able to solubilize phosphate; and 390 were siderophores producers. The inoculation of sugarcane with Gluconacetobacter diazotrophicus VI27 strain showed a significant increase in the number of sets germinated, in the amount of soluble solids, and in the yield of sugarcane juice compared with the control. As a conclusion, a diverse population of PGP bacteria was found in the sugarcane samples. These bacteria, especially G. diazotrophicus strain VI27, could be used as biofertilizers of sugarcane as well as other cereal crops under controlled conditions to avoid or reduce the use of standard N fertilizers.     

Endangered economic species of Indian desert

The economically important, naturally occurring species of the Indian desert was surveyed on the basis of the perception of local plant scientists. About one-fourth of the total 84 taxa were seen to be facing varying stages of risk. Of these, 17 species and 8 botanical varieties are endemic to Indian desert. Eighteen species in Bikaner, 21 in Jaisalmer and 19 in Jodhpur divisions were reported to be at risk. Factors responsible for the loss of species diversity have been discussed and appropriate strategies have been suggested for their conservation.     

Evaluation of genetic diversity and plant growth promoting activities of nitrogen-fixing bacilli isolated from rice fields in South Brazil

Several strains of bacilli, mainly species of the genera Bacillus and Paenibacillus, displaying important plant growth promoting (PGP) characteristics were isolated from seven distinct rice production zones of the Rio Grande do Sul State, Brazil. Of 296 isolates, 155 were from rhizospheric soil and 141 from bulk soil. In order to evaluate the diversity among the isolates of each bacterial population the Shannon index was used on a 70% similarity basis. Diversity indices varying from 2.27 to 5.51 were obtained. Using principal coordinate analysis (PCA) to correlate bacterial diversity with soil parameters, it was found that soil pH was the characteristic most closely related to bacilli diversity. The bacilli isolated were also analyzed for some PGP activities. Of those 296 isolates, 94 and 148 produced between 0.1 and 30 μg of indole-3-acetic acid (IAA) ml⁻¹ in vitro after 72 and 144 h of incubation, respectively. Twenty-two isolates were able to solubilize phosphate and 32 isolates produced siderophores. Paenibacillus and Bacillus genera were the most prominent groups in the rhizosphere and soil populations analyzed. Paenibacillus borealis was the most frequent species in both locations. The isolate SVPR30, identified by 16S rRNA gene sequence analysis as a strain of Bacillus sp., was chosen for in vivo greenhouse experiments and proved to be very efficient in promoting a significant increase in the roots and shoot parts of rice plants. The identification and isolation of PGP bacilli from temperate and subtropical soils, which combine the ability to fix nitrogen with the production of substances capable to promote the plant growth, could significantly increase productivity of grain crops in Brazil.     

Accumulation of metals in macrophytes from water reservoirs of a power supply plant, Rio de Janeiro State, Brazil

Aquatic macrophytes are well known accumulators for heavy metals, the reason why they are used as bioindicators for water quality and in phytoremediaton strategies. This study reports on the elemental concentrations in four free-floating aquatic macrophytes (S. auriculata; P. stratiotes; E. crassipes and E. azurea) growing in two water reservoirs (Santana e Vigário, Rio de Janeiro State, Brazil) of an electric power plant that receive input from the polluted Paraíba do Sul River. Filtered water samples and water suspended solids from these environments were also analysed. Inductively coupled plasma mass spectrometry was used as the principal method, allowing the determination of up to 41 elements, including the rare-earth elements (REEs) and other trace metals not assayed before in these macrophytes. The results show that all elements studied are accumulated by the macrophytes with concentration ratios (CR = [plant]: [water]) varying from about 1,000 to 200,000, based on the dry weight of the plant species. With a few exceptions, highest accumulations were observed in E. crassipes in which CRs increase in the sequence: Cu < Mo < Cr < Pb < Tl < Fe < La < Zn < Ce< Mn. Surprisingly high CRs (e.g. Ce: 74,000) and corresponding mass concentrations were observed for the rare-earth elements (e.g. ∑REE: 112 mg kg^?1), also measured in the water suspended particle fraction. The results show that this fraction acts as an effective sink for trace metals in the aquatic system studied and seems to play also an important role in the transfer of metals from water to the plant species.     

Exposure to metallic mercury in workers in a tropical chloralkali plant evaluated through urine analysis,Rio de Janeiro,Brazil.

Occupational exposure to Hg vapour was investigated in 78 workers during three periods with different temperatures: August 1991, December 1991, and February 1992. Each individual was sampled twice in each period; before and after a six working days period (with a two free days interval). As an attempt to normalise Hg excretion urine was sampled always after a normal 8 hours night sleeping and immediately frozen. Mineralisation was done with acid and oxidant mixture and determination by cold vapour Atomic Absorption Spectrophotometry (Varian VGA-76 and AA-1475). Analytical accuracy was controlled by routine analysis of certified reference material (Seronorm TM trace elements, Nycome As diagnostics Olso - Norway) and all samples were analysed in triplicates. Of a total of 355 samples analysed 13% were over the maximum limit for occupational exposure (50 µg.l-1 or ppb). From the 78 individuals investigated 13% presented average value smaller than 10 ppb; just 8% had the average over 50 ppb; 64% showed averages smaller than 30 ppb; and 28% were between 30 and 50 ppb. Seasonal variation was observed with the highest values in the hottest periods. High variability was observed in the same individual even within an interval of just few days (seven days). No increase of Hg in urine after the six days of exposure was observed when compared with the values after the two free days interval.     

Endangered mammals of Chile: Status and conservation

The native mammalian fauna of Chile has suffered reductions in distribution and abundance. Of the 78 species of native mammals, 22 species plus 15 races of 5 additional species are of conservation concern. The status of each of these threatened taxons is given, using IUCN criteria, along with a discussion of the reasons for their status of concern. Exploitation for meat or pelts combined with habitat deterioration are the most prevalent reasons for the endangering of wildlife in Chile. Central Chile, the most developed and populated region, has the highest proportion of mammalian fauna of conservational concern, followed closely by arid northern Chile. Chilean authorities, with international assistance, have made progress in addressing these problems but much remains to be done that will require continued international assistance if many unique forms are to be preserved.     

Mountain lion depredation in southern Brazil

Mountain lion (Puma concolor) depredation incidents on livestock herds were recorded at 15 ranches in southern Brazil from 1993 to 1995. Maximum losses to mountain lions were 78% for goats, 84% for sheep, and 16% for cattle. Cattle mortality arising from causes other than depredation assumed a greater importance in herd productivity. In contrast, attacks on sheep and goats were more frequent than losses to other causes, but could be reduced to acceptable levels when flocks were corralled at night. Most depredation incidents occurred when weather and light conditions were unfavorable to human activity. We explain these patterns and inter-ranch variation in depredation rates on the basis of a risk-avoidance strategy by the mountain lions. Stock losses can be minimized by understanding these patterns and by applying appropriate herd husbandry, thus reducing the urge to persecute this protected species.     

Evolution of Mercury Contamination in Brazil

This paper reviews the history of Hg contamination in Brazil by characterizing and quantifying two major sources of Hg emissions to the environment: industrial sources and gold mining, industry was responsible for nearly 100% of total Hg emissions from the late 1940's to the early 1970's, when efficient control policies were enforced, leading to a decrease in emissions. Gold mining, on the other hand was nearly insignificant as a Hg source up to the late 1970's, but is presently responsible for over 80% of total emissions. Presently, over 210 t of Hg are released into the environment in Brazil annually. Nearly 170 t come from gold mining operations. 17 t come from chlor-alkali industry and 10 t come from all other industrial uses. Emissions to the atmosphere are the major pathway of Hg releases to the environment and reach over 160 t.yr-1 with approximately 136 t.yr-1 from gold mining.     

Trends on Soil Science in Brazil

Journal of Soils and Sediments -     

Impact of atmospheric CO2 and plant life forms on soil microbial activities

From the global change perspective, increase of atmospheric CO₂ and land cover transformation are among the major impacts caused by human activities. In this study, we are addressing the combined issues of the effect of CO₂ concentration increase and plant type on soil microbial activities by asking how annual and perennial plant groups affect soil microbial processes under elevated CO₂. The experimental design used a mix of species of different growth forms for both annuals and perennials. Our objective was: (1) to determine how two years of annual or perennial plant cover and CO₂ enrichment could affect Mediterranean soil microbial processes; (2) to test the resistance and the resilience of these soil functional processes after a natural perturbation. We determined the effects of 2 years atmospheric CO₂ enrichment on soil potential respiration (SIR), denitrification (DEA) and nitrification (NEA) activities. We could not find any significant effect of CO₂ increase on SIR, DEA and NEA. However, we found a strong effect of the plant cover type, i.e. annuals versus perennials, on the potential microbial activity related to N cycling. DEA and NEA were significantly higher in soil under annual plants while SIR was not significantly different. To determine whether these changes would survive a natural perturbation, we carried out a rain event experiment once the experimental treatments (i.e. different plant cover and atmospheric CO₂ concentration) were stopped. The soil potential respiration, as expressed by the SIR, was not affected and remained stable. DEA rates converged rapidly under annuals and perennials after the rain event. Under both annuals and perennials NEA increased significantly after the rain event but remained significantly higher in the soil with annual plants. The relative change of the soil microbial processes induced by annual and perennial plants was inversely related to the density and the diversity of the corresponding microbial functional groups.     

Responses of cycads with different life histories to the impact of plant collecting: simulation models to determine important life history stages and population recovery times

Collection of plants and seeds from wild populations threatens a large number of cycad species. We investigated to what extent individual life history stages contribute to population growth (λ) and compared two species with major differences in life histories in the African genus Encephalartos: Encephalartos cycadifolius, a highly persistent grassland species that resprouts after fire, and Encephalartos villosus, a relatively fast growing, non-sprouting forest species. Several harvesting scenarios impacting different sized individuals were simulated to determine the sensitivity of the two functional types to harvesting. In both species λ was most sensitive to changes in abundance of adult plants. The harvesting of seeds had minimal impact on population growth rates, whereas harvesting of adult plants led to rapid population decline. This response from two very different functional types suggests that the conservation of adult plants is critical for all cycad species. Despite similar responses to adult mortality, the two species had substantially different population growth rates. This determined recovery time after harvesting of adult individuals. Encephalartos cycadifolius is typical of highly persistent plant species associated with low levels of recruitment and unable to recover from even small losses of adults within a reasonable conservation time frame (<100 years). Our results suggest that the ability to recover from loss of individuals is an important factor that should be considered when assessing the vulnerability of wild populations to threats.     

濒危植物急尖长苞冷杉种群生命表分析

急尖长苞冷杉是我国二级保护植物,处于易危状态.在西藏色季拉山,对急尖长苞冷杉种群全面调查的基础上,以种群生命表及生存理论为基础,编制色季拉山阳坡、阴坡及总体急尖长苞冷杉种群特定时间生命表,分别绘制存活曲线、死亡率曲线、亏损率曲线,以及积累死亡率函数、死亡密度甬数和危险率函数曲线,并分析种群动态变化.结果表明:生长在阳坡、阴坡及总体的急尖长苞冷杉种群各龄级个体数量均随年龄增长呈直线下降趋势,生境对种群的结构和动态有较大影响,幼苗死亡率阴坡大于阳坡,老龄个体死亡率阳坡大于阴坡;生长在阳坡种群的存活曲线属Deevey-Ⅱ型中的B3亚型,生长在阴坡种群的存活曲线属Deevey-Ⅲ型,总体种群的存活曲线也属Deevey-Ⅲ型;三个生命表中引入的几个函数都能较好地说明了种群的结构和动态变化.研究结果可为该资源的管理及持续利用提供理论依据.     

濒危植物艾比湖桦生存的水文地质及土壤条件

初步研究发现,艾比湖桦仅见于古尔图河古老三角洲西缘泉水溢出地带.虽地处温带漠境,但土壤却系既无盐化又无碱化且碳酸钙含量很低的草甸沼泽土,地下水矿化度小于1g/L,pH值6.9～7.4.     

Enzyme activities in Cerrado soils of Brazil

Abstract

Enzymes play an important role in cycling of organically bound nutrients in soils. Pyrophosphatase (PPi), acid phosphatase (AP), arylsulfatase (AS), urease (UR), and dehydrogenase (DH) activities were measured in air‐dry samples from the top 15 cm of two dark red Latosols and four red‐yellow Latosols from Cerrado regions of Minas Gerais (MG) and Goias (GO) Brazil. Relationships between enzyme activities and soil properties were examined. Among the six soils, the dark red Latosol from Sete Lagoas, MG, had the highest activities for AP, AS, and UR enzymes. The lowest activities for these enzymes were observed in a dark red Latosol from Uberaba, MG, and this soil also recorded the lowest DH activity. The red‐yellow Latosol from Sete Lagoas, MG, had the highest PPi and DH. The activities, whereas a red‐yellow Latosol from Felixlandia, MG, gave the lowest PPi activity. Activities of all enzymes were negatively correlated with sand and silt content and positively correlated with clay content. Overall, the enzyme activities were positively correlated with pH, organic carbon (C), Bray‐P, and exchangeable potassium (K), calcium (Ca), and magnesium (Mg). Soil organic C appears to have the greatest effect on the level of enzyme activities in acid soils. Each soil type has its own inherent levels of enzyme activities. Knowledge of relationships between enzyme activities and soil properties could be useful in development of sound fertilizer practices for Cerrado soils.     

Nutrient Elements in Leaves of Rare and Endangered Species in Wuhan Botanical Garden,China

Characteristics of mineral elements in plants are often strongly influenced by species' abundance and heterogeneous habitats. Therefore, nutrient analysis, after excluding interference of habitat heterogeneity, would directly reflect genetic traits of species in the community. From another aspect, knowledge of responses of species to environmental variation would be helpful in the management of natural and man-made ecosystems, especially those containing rare and endangered plants conserved in gardens. We studied the characteristics of twelve nutrient elements in 90 species in Wuhan Botanical Garden (WBG) and provided explanations of their survival status.

Concentrations of the 12 nutrients in the artificial garden were consistent with those in other natural communities in the subtropical zone of China. Features of nutrient-limited at the community level were also consistent with the regional characteristics (N:P ratio being 9.79 ± 3.22, as exhibiting N-limited). The Ca + Mg concentrations differed between evergreen and deciduous species. The 90 species were clustered into various functional nutrition groups.

The artificial community of the garden was a “sick” one relative to natural ones with wholesome ecological functions. The proportion of element-pairs with significant correlations (P < 0.01 or P < 0.05) to total element-pairs was only 24.2%, being lower than that of species in the natural community, This suggests that the harmonious relationship among nutrient elements in these species was yet to be achieved. Correlation analysis between survival status of the 90 species and their foliar nutrient ratios were positive for nitrogen (N), phosphorus (P), potassium (K), iron (Fe), zinc (Zn), copper (Cu), and sodium (Na), but negative for calcium (Ca), magnesium (Mg), manganese (Mn), and aluminum (Al). Cluster analysis suggested that, among 23 species with the poorest survival status, 21 species had higher Ca and Mg, but lower N and P concentrations.     

秸秆直燃发电供应链气体及颗粒污染物排放的生命周期评价

秸秆发电以其极好的环保效用和可再生能源利用引起各界关注,但是由于秸秆轻、薄、散的特性,导致在秸秆收集和运输的效率十分低下,从而会消耗大量石化燃料,排放出大量的气体及颗粒污染物,加之秸秆发电供应链的终端直燃发电也会排放一定污染物,必然会对其环保效用带来影响。该文依据生命周期评价方法,通过建立4个秸秆发电供应链场景,包含秸秆收集、打捆、运输存储、解包破碎以及最终发电等阶段,对其中机械及车辆石化燃料的消耗以及污染物的排放进行定量计算,发现4个秸秆发电供应链的污染物排放有较大差距,其中CO2相差1.2～2倍,CO相差1.4～5.4倍,NOX相差1.5～4.2倍,PM相差1.4～6.5倍。秸秆发电供应链环保效果与秸秆发电供应链中收集、预处理及运输存储模式有较大关系,预处理压缩环节、短距离农用车运输及压缩后道路运输距离是关键,这些因素的合理配置直接关系到秸秆发电供应链环保效用的高低。对秸秆发电供应链的整体排放以处理单位质量秸秆排放的污染气体和可吸入颗粒排放指数为标准,通过与秸秆露天燃烧和燃煤发电供应链对比分析,发现相对秸秆露天燃烧PM排放指数12.95 g/kg,秸秆发电供应链的PM排放指数为0.12 g/kg;相对燃煤发电供应链CO2排放指数1 010.1 g/kg,秸秆发电供应链的CO2排放指数为43.44 g/kg,在减少由露天焚烧秸秆造成的应急性雾霾天气和减少碳排放方面有积极作用。