Historic landscape change and habitat loss: the case of black grouse in Lower Saxony,Germany

The declines of many specialist bird species in the agricultural landscapes of Central Europe have resulted in small and isolated populations. In the case of the black grouse, a ground-nesting bird species with large spatial requirements, empiric evidence about underlying landscape changes is scarce. In this study, we examined land cover and land cover changes in a farmland-forest mosaic in eastern Lower Saxony, Germany and how they affect occurrence and persistence of black grouse. Spatial information came from historic topographic maps from 1958 to 1975. The results show profound conversions of habitat to forest and farmland but also an increase in settlement area. Habitat conversions and suburbanization were negative correlates of black grouse persistence. Habitat models from before and after a decline period differed in some of the predictors and suggest black grouse habitat to be more diverse before the land cover changes. Our study confirms that land use factors at a landscape scale extent contribute to explain black grouse occurrence and thus can complement important small scale factors like the quality and size of individual habitat patches. Results also show that landscape factors affect black grouse distribution predominantly from an area much greater than an individual black grouse home range. Our models may be further evaluated on present-day landscapes and might be used to evaluate large-scale habitat availability for black grouse.     

Precision farming for weed management: techniques

Site-specific weed control techniques have gained interest in the precision farming community over the last years. Managing weeds on a subfield level requires measuring the varying density of weeds within a field. Decision models aid in the selection and adjustment of the treatments, depending on the weed infestation. The weed control can be done either with herbicides or mechanically. A site-specific herbicide application technology can save large amounts of herbicides. Mechanical weed control techniques adapting to the weed situation in the field are applicable to a wide spectrum of crops. Site-specific techniques for the detection and management of weeds are presented. A system for the discrimination of different weed species and crops from images is described, which generates weed maps automatically. Models for the yield effect of weeds are developed and applied in on-farm-research experimental setups. Economic weed thresholds are derived and used for a herbicide application with a patch sprayer.     

Construction and evaluation of a delta cya delta crp Salmonella typhimurium strain expressing avian pathogenic Escherichia coli O78 LPS as a vaccine to prevent airsacculitis in chickens.

Avian pathogenic strains of Escherichia coli cause a number of extraintestinal diseases in poultry, including airsacculitis and colisepticemia. Expression of O78 lipopolysaccharide (LPS) is frequently associated with pathogenic isolates. Salmonella, a common poultry contaminant, is a major public health concern. The purpose of this work was to develop an E. coli vaccine for poultry with the use of an attenuated Salmonella typhimurium carrier that would benefit both the bird and the consumer. Orally administered attenuated S. typhimurium delta cya delta crp strains have been shown to provide excellent protection against wild-type Salmonella challenge in chickens. This work describes the construction of a delta cya delta crp derivative of an avian pathogenic S. typhimurium that expresses both the homologous group B determinants (O1,4,5,12) and the heterologous E. coli O78 LPS O antigens. This was accomplished by inserting the E. coli rfb region, which encodes the genes required for O78 expression, into the chromosomal cya gene of S. typhimurium, creating a defined deletion/insertion mutation. A delta crp mutation was introduced in a subsequent step. Expression of both O antigens was stable in vitro and in vivo. Vaccination of white leghorn chicks at day of hatch and 14 days with the recombinant vaccine strain induced serum immune responses against both S. typhimurium and E. coli LPS and protected the birds against subsequent challenge with an avian pathogenic E. coli O78 strain. Introduction of a mutation in rfc, which encodes the O antigen polymerase, reduced the chain length of the S. typhimurium LPS without affecting the expression of O78. The rfc mutation further enhanced the ability of the vaccine strain to protect chickens against E. coli challenge.     

不同时期施氮对华南双季杂交稻产量及氮素吸收和氮肥利用率的影响

以两系法杂交水稻粤杂122为材料，在广州进行2a4季田间试验，研究了氮素作基肥、蘖肥和穗粒肥施用对水稻氮素吸收、稻谷产量和氮肥利用率的影响。结果表明：施用穗粒肥具有显著的增产作用，其增产效果比基肥和蘖肥好；施用穗粒肥显著提高水稻总吸氮量，基肥和蘖肥对吸氮量影响较小；在总施氮量相同的情况下，氮肥作穗粒肥施用的吸收利用率和农学利用率比基肥和蘖肥高；水稻最适吸氮量随结实期日照时数的增加而提高。控制氮肥总量，适当减少基肥和蘖肥用量，增加穗粒肥用量，实行氮肥后移，有利于提高华南双季杂交稻的产量和氮肥利用率。     

Suitability of dehydrogenase activity assay as an index of soil biological activity

Summary Dehydrogenase activity was studied in typical soils of the Northwest German Lower Plains in order to test some criticisms raised by nannipieri et al. (1990) about methodology. We found that in the same soils with the sampe crop, dehydrogenase activity varies significantly. In the field dehydrogenase activity was dependent on the soil type and not on the cropping system. There is no adequate explanation of these findings. Dehydrogenase activity is a parameter of soil microbiological activity and is influenced by many factors. Either purely accidental the results are or dehydrogenase activity is affected by unknown ecological interactions and by the composition of soil microflora. We conclude that without simultaneous investigations of other microbiological parameters (microbial biomass, ATP levels, enzyme activities, etc.) the measurement of dehydrogenase activity creates confusion and may impede valid ecological comparisons of soils.Dedicated to Prof. H.-P. Blume, Kiel, on the occasion of his 60th birthday     

Optimization of yield and water-use of different cropping systems for sustainable groundwater use in North China Plain

A groundwater crisis is going on in the North China Plain (NCP), due to the excessive water consumption of the traditional winter wheat (WW)/summer maize (SM) double cropping system (two harvests in one year). In order to improve the water use efficiency in this particular cropping system and to evaluate the sustainability of water usage in Chinese agroecosystems, two field experiments were conducted from October 2004 to September 2006 at two sites of the North China Plain. The field experiments included four treatments: (1) farmers’ practice (FP) with two harvests in one year (WW/SM rotation), (2) FP with reduced input (RI) of water and nitrogen (WW/SM rotation), (3) three harvests in two years (TW, 1st year: WW/SM; 2nd year: spring maize), and (4) continuous spring-maize monoculture (CS) with one harvest per year (spring maize). In the treatments RI, TW and CS, the amount and timing of irrigation and nitrogen fertilization was optimized using TDR based soil moisture measurements and the N_min-method, respectively. Data showed that the utilization efficiency of irrigation water can be improved by optimizing soil water management compared to the traditional water management (FP). However, the groundwater net consumption required for RI still surpassed 300 mm yr⁻¹. Both FP and RI, still overused groundwater resources. The groundwater consumption in the continuous spring maize (CS) was on average 139 mm yr⁻¹. Therefore, the CS system can show the potential to use groundwater sustainably in the long term. Water usage of the TW treatment was in between the water usage of the other treatments. The grain yields in the double cropping systems (FP and RI) were higher than that in the two other systems (TW and CS). But the CS treatment showed the higher W_UE than others.     

<Emphasis Type="Italic">Dactylonectria torresensis</Emphasis> as the Main Component of the Black Root Rot Complex of Strawberries and Raspberries in Northern Germany

In a long-term survey of black root rot of strawberries and raspberries in Northern Germany in 2007–2014, fungi with and without Cylindrocarpon-like anamorphs were isolated as potential pathogens. Dactylonectria torresensis was the most common species, being isolated from 18% of strawberry roots obtained from nursery plants and 37% of roots from production fields, as well as 21% and 29% (respectively) of raspberry roots. Less frequently isolated fungi with Cylindrocarpon-like anamorphs included Ilyonectria crassa, Ilyonectria sp. 2, I. pseudodestructans, I. robusta, C. obtusisporium and Ilyonectria sp. 1. Severe disease symptoms were reproduced by artificial inoculation of strawberries with D. torresensis, I. crassa and Ilyonectria sp. 2, milder symptoms with C. obtusisporium. A wide range of other root-pathogenic fungi such as Fusarium oxysporum, Verticillium dahliae, Ceratobasidium fragariae, Gnomoniopsis fructicola, Hainesia lythri, and species of Cadophora, Leptodontidium, Pythium, Phytophthora, Plectosporella, Pestalotiopsis and Truncatella were either isolated only sporadically or were not associated with black root rot symptoms, suggesting that they did not play any major role in this disease in Northern Germany. Visible disease symptoms and high frequencies of D. torresensis isolations in many batches of nursery plants indicated that these may comprise a major source of contamination of production fields. The previously unrecognised prominence of D. torresensis resolves a long-standing puzzle concerning the cause of the ongoing black root rot epidemic in Northern German strawberry and raspberry production.     

Joint Temporal Point Pattern Models for Proximate Species Occurrence in a Fixed Area Using Camera Trap Data

The distinction between an overlap in species daily activity patterns and proximate co-occurrence of species for a location and time due to behavioral attraction or avoidance is critical when addressing the question of species co-occurrence. We use data from a dense grid of camera traps in a forest in central North Carolina to inform about proximate co-occurrence. Camera trigger times are recorded when animals pass in front of the camera’s field of vision. We view the data as a point pattern over time for each species and model the intensities driving these patterns. These species-specific intensities are modeled jointly in linear time to preserve the notion of co-occurrence. We show that a multivariate log-Gaussian Cox process incorporating both circular and linear time provides a preferred choice for modeling occurrence of forest mammals based on daily activity rhythms. Model inference is obtained under a hierarchical Bayesian framework with an efficient Markov chain Monte Carlo sampling algorithm. After model fitting, we account for imperfect detection of individuals by the camera traps by incorporating species-specific detection probabilities that adjust estimates of occurrence and co-occurrence. We obtain rich inference including assessment of the probability of presence of one species in a particular time interval given presence of another species in the same or adjacent interval, enabling probabilities of proximate co-occurrence. Our results describe the ecology and interactions of four common mammals within this suburban forest including their daily rhythms, responses to temperature and rainfall, and effects of the presence of predator species. Supplementary materials accompanying this paper appear online.     

Choosing best practices for managing impacts of trawl fishing on seabed habitats and biota

Bottom trawling accounts for almost one quarter of global fish landings but may also have significant and unwanted impacts on seabed habitats and biota. Management measures and voluntary industry actions can reduce these impacts, helping to meet sustainability objectives for fisheries, conservation and environmental management. These include changes in gear design and operation of trawls, spatial controls, impact quotas and effort controls. We review nine different measures and actions and use published studies and a simple conceptual model to evaluate and compare their performance. The risks and benefits of these management measures depend on the extent to which the fishery is already achieving management objectives for target stocks and the characteristics of the management system that is already in place. We offer guidance on identifying best practices for trawl‐fisheries management and show that best practices and their likelihood of reducing trawling impacts depend on local, national and regional management objectives and priorities, societal values and resources for implementation. There is no universal best practice, and multiple management measures and industry actions are required to meet sustainability objectives and improve trade‐offs between food production and environmental protection.