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1.
The cultivation of fast growing trees on agricultural sites is an area undergoing a growth in interest due to the rising demand for woody biomass as a source of bioenergy. Short rotation alley cropping systems (SRACS) represent a promising possibility to combine annual crops for food, fodder or bioenergy with woody plants for biomass production, doing so through an integration of hedgerows of fast growing trees into conventional agricultural sites. Against such developments, the question has arisen as to what extent hedgerows in SRACS can act as an effective windbreak despite their management-related low height of only a few meters. On the basis of multiannual recorded wind velocity data in high resolution at two sites in Germany, it could be shown that the wind speed on crop alleys was reduced significantly by such hedgerows. At the central point of 24 m wide crop alleys, the wind speed decreased on an annual average basis by more than 50 % when compared to the wind speeds of open field. The overall amount of reduction was strongly dependent on the location within the crop alleys, the height of trees, the distance between two hedgerows, and their orientation. In reflection upon these results, it was concluded that the establishment of SRACS could lead to enhanced soil protection against wind erosion and thus to ecological and economic benefits for agricultural sites. 相似文献
2.
Penka Tsonkova Christian B?hm Ansgar Quinkenstein Dirk Freese 《Agroforestry Systems》2012,85(1):133-152
In temperate Europe alley cropping systems which integrate strips of short rotation coppices into conventional agricultural fields (ACS) are receiving increasing attention. These systems can be used for crops and woody biomass production at the same time, enabling farmers to diversify the provision of market goods. Adding trees into the agricultural land creates various additional benefits for the farmer and society, also known as ecosystem services. However, tree-crop interactions in the temperate region have not been adequately substantiated which is identified as a drawback to the practical implementation of such systems. In order to bridge this gap, the current paper aims to present a comprehensive overview of selected ecosystem services provided by agroforestry with focus on ACS in the temperate region. The literature indicates that compared with conventional agriculture ACS have the potential to increase carbon sequestration, improve soil fertility and generally optimize the utilization of resources. Furthermore, due to their structural flexibility, ACS may help to regulate water quality, enhance biodiversity, and increase the overall productivity. ACS are shown as suitable land use systems especially for marginal sites. Based on the available data collected, we conclude that ACS are advantageous compared to conventional agriculture in many aspects, and therefore suggest that they should be implemented at a larger scale in temperate regions. 相似文献
3.
Before European settlement the plains bison (Bison bison bison) numbered in the tens of millions across most of the temperate region of North America. Within the span of a few decades during the mid- to late-1800s its numbers were reduced by hunting and other factors to a few hundred. The plight of the plains bison led to one of the first major movements in North America to save an endangered species. A few individuals and the American Bison Society rescued the remaining animals. Attempts to hybridize cattle and bison when bison numbers were low resulted in extensive cattle gene introgression in bison. Today, though approximately 500,000 plains bison exist in North America, few are free of cattle gene introgression, 96% are subject to anthropogenic selection for commodity production, and only 4% are in herds managed primarily for conservation purposes. Small herd size, artificial selection, cattle-gene introgression, and other factors threaten the diversity and integrity of the bison genome. In addition, the bison is for all practical purposes ecologically extinct across its former range, with multiple consequences for grassland biodiversity. Urgent measures are needed to conserve the wild bison genome and to restore the ecological role of bison in grassland ecosystems. Socioeconomic trends in the Great Plains, combined with new information about bison conservation needs and new conservation initiatives by both the public and public sectors, have set the stage for significant progress in bison conservation over the next few years. 相似文献
4.
Seth Nii-Annang Holger Grünewald Dirk Freese Reinhard F. Hüttl Oliver Dilly 《Biology and Fertility of Soils》2009,45(5):531-538
The impact of alley cropping on post-lignite mine soils developing from quaternary deposits after 9 years of recultivation
was evaluated on the basis of microbial indicators, organic C and total N contents, and the isotope characteristics of soil
C. Soils were sampled at the 0 to 3, 3 to 10, and 10 to 30 cm depths under black locust (Robinia pseudoacacia L.), poplar (Populus spp.), the transition zone and in the middle of alley under rye (Secale cereale). There was no significant effect of vegetation on microbial properties presumably, due to the high variability, whereas organic
C and total N contents at the 0- to 3-cm layer were significantly higher under black locust and poplar than in the transition
zone and rye field. Organic C total N contents, and basal respiration, microbial biomass, and microbial quotient decreased
with soil depth. Soil organic C and total N contents were more than doubled after 9 years of recultivation, with annual C
and N accretion rate of 162 g C
org m−2 year−1 and 6 g N
t m−2 year−1. Microbial properties indicated that the soils are in early stages of development; the C isotope characteristics confirmed
that the sequestered C was predominantly from C3 plants of the alley cropping. 相似文献
5.
Freese L Scholdberg TA Burton DD Norden TD Shokere LA Jenkins GR 《Journal of agricultural and food chemistry》2007,55(15):6060-6066
Homogeneity analysis was performed on four distinctive commercial lots, derived from the 2006 rice harvest in the United States. Lots that had previously been tested and suspected to have some level of LL601 were selected to determine lot homogeneity. LL601 infiltration in the lots was low and estimated to contain <0.01% (sigma = 0.026), 0.014% (sigma = 0.020), 0.054% (sigma = 0.043), and 0.074% (sigma = 0.031) LL601. Lots were analyzed statistically as a one-way classification, or one-factor experiment, to assess the presence of strata within the lot. A p value of 0.05 or lower is needed to declare statistical significance and would suggest significant differences among the samples. The data revealed p values ranging between 0.105 and 0.607. The calculated p values for all lots were greater than the critical value of 0.05. Samples taken from different locations throughout these four commercial lots did not show statistically significant stratifications within the lot. 相似文献
6.
The aim of this study was to evaluate the potential of short rotation alley cropping systems (SRACS) to improve the soil fertility of marginal post-mining sites in Brandenburg, Germany. Therefore, we annually investigated the crop alleys (AC) and black locust hedgerows (ABL) of a SRACS field trail under initial soil conditions to identify the short-term effects of tree planting on the storage of soil organic carbon (SOC) and its degree of stabilization by density fractionation. We detected a significant increase in SOC and hot-water-extractable organic C (HWEOC) at ABL, which was mainly restricted to the uppermost soil layer (0–10 cm). After 6 years, the SOC and HWEOC accumulation rates at ABL were 0.6 Mg and 46 kg ha?1 year?1, which were higher than those in the AC. In addition, comparatively high stocks of approximately 4.6 Mg OC and 182 kg HWEOC ha?1 were stored in the ABL litter layer. Density fractionation of the 0–3 cm soil layer at ABL revealed that the majority of the total SOC (47%) was stored in the free particulate organic matter fraction, which was more than twice that of the AC. At the same time, a higher and steadily increasing amount of SOC was stored in the occluded particulate organic matter fraction at ABL, which indicated a high efficiency for SOC stabilization. Overall, our findings support the suitability of black locust trees for increasing the soil fertility of the reclaimed mining substrate and, consequently, the high potential for SRACS to serve as an effective recultivation measure at marginal sites.
相似文献7.
8.
Comparison of jugular and transverse facial venous sinus blood analytes in healthy and critically ill adult horses 
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Eduardo S. Matos Dirk Freese Anna Śla̧zak Ute Bachmann Maik Veste Reinhard F. Hüttl 《植物养料与土壤学杂志》2010,173(5):654-661
The objective of this work was to evaluate the C and N stocks and organic‐C fractions in soil under mixed forest stands of Scots pine (Pinus sylvestris L.) and Sessile oak (Quercus petraea [Matt.] Liebl.) of different ages in NE Germany. Treatments consisted of pure pine (age 102 y), and pine (age 90–102 y) mixed with 10‐, 35‐, 106‐, and 124‐y‐old oak trees. After sampling O layers, soils in the mineral layer were taken at two different depths (0–10 and 10–20 cm). Oak admixture did not affect total organic‐C (TOC) and N stocks considering the different layers separately. However, when the sum of TOC stocks in the organic and mineral layers was considered, TOC stocks decreased with increasing in oak age (r2 = 0.58, p < 0.10). The microbial C (CMB) was not directly correlated with increase of oak age, however, it was positively related with presence of oak species. There was an increase in the percentage of the CMB‐to‐TOC ratio with increase of oak‐tree ages. On average, light‐fraction C (CLF) comprised 68% of the soil TOC in upper layer corresponding to the highest C pool in the upper layer. CLF and heavy‐fraction C (CHF) were not directly affected by the admixture of oak trees in both layers. The CHF accounted on average for 30% and 59% of the TOC at 0–10 and 10–20 cm depths, respectively. Despite low clay contents in the studied soils, the differences in the DCB‐extractable Fe and Al affected the concentrations of the CHF and TOC in the 10–20 cm layers (p < 0.05). Admixture of oak in pine stands contributed to reduce topsoil C stocks, probably due to higher soil organic matter turnover promoted by higher quality of oak litter. 相似文献
10.
Holden MJ Blasic JR Bussjaeger L Kao C Shokere LA Kendall DC Freese L Jenkins GR 《Journal of agricultural and food chemistry》2003,51(9):2468-2474
Sensitive and accurate testing for trace amounts of biotechnology-derived DNA from plant material requires pure, high-quality genomic DNA as template for subsequent amplification using the polymerase chain reaction (PCR). Six methodologies were evaluated for extracting DNA from ground corn kernels spiked with 0.1% (m/m) CBH351 (StarLink) corn. DNA preparations were evaluated for purity and fragment size. Extraction efficiency was determined. The alcohol dehydrogenase gene (adh1) and the CBH351 (cry9C, 35S promoter) genes in the genomic DNA were detected using PCR. DNA isolated by two of the methods proved unsuitable for performing PCR amplification. All other methods produced some DNA preparations that gave false negative PCR results. We observed that cornstarch, a primary component of corn kernels, was not an inhibitor of PCR, while acidic polysaccharides were. Our data suggest that amplification of an endogenous positive control gene, as an indicator for the absence of PCR inhibitors, is not always valid. This study points out aspects of DNA isolation that need to be considered when choosing a method for a particular plant/tissue type. 相似文献