Placing the pieces: Reconstructing the original property mosaic in a warrant and patent watershed

Recent research shows that land use history is an important determinant of current ecosystem function. In the United States, characterization of land use change following European settlement requires reconstruction of the original property mosaic. However, this task is difficult in unsystematically surveyed areas east of the Appalachian Mountains. The Gwynns Falls watershed (Baltimore, MD) was originally surveyed in the 1600-1700s under a system of warrants and patents (commonly known as ‘metes and bounds’). A method for the reconstruction and mapping of warrant and patent properties is presented and used to map the original property mosaic in the Gwynns Falls watershed. Using the mapped mosaic, the persistence of properties and property lines in the current Gwynns Falls landscape is considered. The results of this research indicate that as in agricultural areas, the original property lines in the Gwynns Falls watershed are persistent. At the same time, the results suggest that the property mosaic in heavily urbanized/suburbanized areas is generally ‘reset.’ Further, trends in surveying technique, parcel size, and settlement patterns cause property line density and property shape complexity to increase in the less urbanized upper watershed. The persistence of original patterns may be damping expression of heterogeneity gradients in this urban landscape. This spatial pattern of complexity in the original mosaic is directly opposite of hypothesized patterns of landscape heterogeneity arising from urbanization. The technique reported here and the resulting observations are important for landscape pattern studies in areas settled under unsystematic survey systems, especially the heavily urbanized areas of the eastern United States. This revised version was published online in July 2006 with corrections to the Cover Date.     

Plant species traits regulate methane production in freshwater wetland soils

Ecosystem and biogeochemical responses to anthropogenic stressors are the result of complex interactions between plants and microbes. A mechanistic understanding of how plant traits influence microbial processes is needed in order to predict the ecosystem-level effects of natural or anthropogenic change. This is particularly true in wetland ecosystems, where plants alter the availability of both electron donors (e.g., organic carbon) and electron acceptors (e.g., oxygen and ferric iron), thereby regulating the total amount of anaerobic respiration and the production of methane, a highly potent greenhouse gas. In this study, we examined how plant traits associated with plant inputs of carbon (photosynthesis and biomass) and oxygen (root porosity and ferric iron on roots) to mineral soils relate to microbial competition for organic carbon and, ultimately, methane production. Plant productivity was positively correlated with microbial respiration and negatively correlated to methane production. Root porosity was relatively constant across plant species, but belowground biomass, total biomass, and the concentration of oxidized (ferric) iron on roots varied significantly between species. As a result the size of the total root oxidized iron pool varied considerably across plant species, scaling with plant productivity. Large pools of oxidized iron were related to high CO₂:CH₄ ratios during microbial respiration, indicating that as plant productivity and biomass increased, microbes used non-methanogenic respiration pathways, most likely including the reduction of iron oxides. Taken together these results suggest that increased oxygen input from plants with greater biomass can offset any potential stimulation of methanogenic microbes from additional carbon inputs. Because the species composition of plant communities influences both electron donor and acceptor availability in wetland soils, changes in plant species as a consequence of anthropogenic disturbance have the potential to trigger profound effects on microbial processes, including changes in anaerobic decomposition rates and the proportion of mineralized carbon emitted as the greenhouse gas methane.     

不同收晾方式对马里兰烟品质的影响

为提高马里兰烟的品质,采用3种不同的收晾方式(全剥叶划筋晾制,全剥叶不划筋晾制,半整株晾制)处理马里兰烟后测定其理化性质和感官品质。结果表明:马里兰烟中上部叶的质量受收晾方式影响较大;产值表现为全剥叶不划筋晾制全剥叶划筋晾制半整株晾制;全剥叶不划筋晾制烟叶的内在化学成分较协调、评吸质量较好;半整株晾制烟叶的化学成分及评吸质量次之,但其TSNAs总量及其NNK含量低;全剥叶划筋最差。因此,采用全剥叶不划筋和半整株砍收相结合的收晾方式,提高马里兰烟的品质。     

晾烟房温湿度调节装置对马里兰烟晾制的影响

将专利"晾烟房温湿度调节装置"(专利号:ZL200820066396.X)应用到马里兰烟调制中,形成保温晾房,可明显提升平均温度,较标准晾房日平均温度提高1～2℃,相对湿度降低5%～10%,且保温保湿时间较长,有利于马里兰烟凋萎变色,烟叶晾制质量较好,降低烟叶含青程度和减少霉烂烟叶,提高有效产量7.6%左右,上等烟比率提高11.4%左右,上中等烟率提高5.0%左右.试验表明,保温晾房和标准晾房晾制的烟叶化学成分均较协调,保温晾房使烟碱含量提高0.13%～0.81%,总氮含量提高0.77%～1.03%.烟叶钾含量提高0.20%左右,总糖含量降低0.08%～0.34%,烟叶氟离子含量差异较小,均在0.50%左右.     

马里兰大学图书馆印象

马里兰大学图书馆由1 个主馆、7 个分馆组成,实行分工联合服务。馆舍条件优越,馆藏资源丰富。服务内容呈现出专业服务、空间服务、技术服务、馆藏服务并举的多元化格局。注重用户的信息素养教育,成效显著。多途径与其他机构合作,使资源共享梦想成真。面向校外社区开放,使图书馆真正成为没有围墙的学习场所。     

马里兰烟不同晾制方式的比较

[目的]探讨马里兰烟晾制方式的最佳组合。[方法]采用双因素单重复设计研究了不同晾制处理对马里兰烟晾制质量的影响。f结果]处理⑩的马里兰烟产量最高。麦庄村和万里村保温晾房晾制的马里兰烟产量分别比标准晾房晾制提高了7．7％和7．5％。处理⑧的马里兰烟产值最高。麦庄村和万里村保温晾房晾制的马里兰烟产值分别比标准晾房晾制提高了10．8％和12．5％。保温晾屠晾制的中、上部烟叶的质量高于标准晾房晾制的烟叶。标准晾房晾制的上部二级烟叶的烟碱含量低于4％,保温晾房晾制的上部二级烟叶的烟碱含量为4％～5％。保温晾房晾制烟叶的总氮含量和钾含量略高于标准晾房晾制的烟叶。[结论]前期保温晾房晾制＋后期两段式干筋棚晾制的晾制组合的马里兰烟产质量最佳,     

Effects of immunocontraception on a suburban population of white-tailed deer Odocoileus virginianus

Abundant populations of white-tailed deer (Odocoileus virginianus) in North America have altered the structure of some forest communities and caused serious conflicts with farmers, gardeners, and motorists, encouraging the search for novel techniques to control populations of deer and other wildlife. We administered the porcine zona pellucida (PZP) immunocontraceptive vaccine to female white-tailed deer living on the 233-ha campus of the National Institute of Standards and Technology (NIST) in Gaithersburg, Maryland, USA. Although some tested PZP preparations proved more effective than others, the number of fawns produced per female was significantly lower in treated than untreated females. Following the onset of contraceptive treatments, the population declined by an average of 7.9% per year, and population declines were larger following years when a higher proportion of females was treated. High mortality due largely to deer-vehicle collisions and low population fertility associated with high deer densities facilitated the observed population decline.     

马里兰烟品种比较试验研究初报

653100 云南省玉溪市聂耳路47号云南省烟草科学研究所     

不同调制方法对烟草烟碱转化及TSNA的影响

为进一步明确调制方式对不同品种(系)烟草烟碱转化和特有亚硝胺(TSNA)的影响,采用裂区试验设计,以白肋烟[B37LC(低烟碱转化)品系、B37HC(高烟碱转化)品系]、马里兰烟[Md609LC(低烟碱转化)品系、Md609HC(高烟碱转化)品系]、烤烟(‘云烟87’、‘K326’)和晒烟(‘深色公会晒黄烟’、‘浅色公会晒黄烟’)等4种烟草类型的8份材料为主处理,烤制、晾制和晒制3种调制方法为副处理,进行了生物碱和4种TSNA含量检测与研究。结果表明:品种(系)是影响生物碱含量、烟碱转化率和4种TSNA含量的主要因素,N?亚硝基降烟碱(NNN)是4种烟草类型的主要TNSA,所占比例在54.35%~97.36%。不同烟草类型中以白肋烟、马里兰的HC品系与LC品系间差异最大,其中LC品系的NNN含量比HC品系下降90.93%和91.54%。3种调制方法中,烟碱含量为烤制晒制晾制,降烟碱及烟碱转化率则为晾制晒制烤制;除N-亚硝基假木贼碱(NAB)含量烤制显著高于晾制外,NNN、4-(N-甲基亚硝胺基)-1-(3-吡啶基)-1-丁酮(NNK)、N-亚硝基新烟碱(NAT)及TSNA总量均为晾制晒制烤制,差异达显著或极显著水平;调制方法对白肋烟、马里兰烟的HC品系影响最大,对LC品系影响最小。综合认为:在烟叶特别是白肋烟、马里兰烟生产上积极推广烟碱转化率低的品种,同时努力改善调制条件、改进调制工艺是降低烟叶TSNA含量、提高烟叶安全性的关键措施。     

酶法制备马里兰烟浸膏的工艺优化及其香味成分分析

为获得优质马里兰烟浸膏,采用酶法制备浸膏,并对制备工艺进行优化得到最佳提取条件,最后对最优条件下制备的浸膏进行香味成分分析,并与非酶解浸膏进行对比。结果表明:马里兰烟浸膏的最优制备工艺为果胶酶∶纤维素酶=1∶1,pH为5,温度为48℃,液料比为9∶1,该条件下,浸膏得率为31.03%。与非酶方法相比,采用酶解的方法浸膏得率提高13.53%;酶解方法与非酶方法相比,马里兰烟浸膏的挥发性香味物质种类从16种增加到23种;香味成分中如苯甲醇、苯乙酸、β-大马烯酮含量增加,分别提高27.64%,69.68%和97.35%;且浸膏中不再检出烟碱。