Predispersal seed predation in Acacia macrostachya,its impact on seed viability,and germination responses to scarification and dry heat treatments

Predispersal seed predation among individual Acacia macrostachya trees over two sites in Burkina Faso was assessed. In addition, the effects of seed predation on seed viability; germination responses to scarification (mechanical, hot water at 60, 70 and 80°C, and sulphuric acid for 10, 20 and 30 min) and dry heat (at 60, 70 and 80°C for 15, 30 and 60 min each) treatments were investigated under laboratory conditions. The results indicated a large difference in predation intensity among individual trees, as well as between sites. Predispersal predation significantly decreased seed germination, particularly when the number of insect larvae per seed increased. Scarified and unscarified seeds germinated equally well, except for hot water treatments of high temperature. This indicates lack of physical dormancy and dispersed seeds can readily germinate provided that conditions for germination are conducive. Seeds exposed to dry heat treatments also germinated close to 97% under low intensity and short exposure times. This suggests that fire, under natural condition, plays a key role in triggering germination of A. macrostachya seeds.     

Effects of historical and present fragmentation on plant species diversity in semi-natural grasslands in Swedish rural landscapes

Habitat loss and fragmentation of natural and semi-natural habitats are considered as major threats to plant species richness. Recently several studies have pinpointed the need to analyse past landscape patterns to understand effects of fragmentation, as the response to landscape change may be slow in many organisms, plants in particular. We compared species richness in continuously grazed and abandoned grasslands in different commonplace rural landscapes in Sweden, and analysed effects of isolation and area in three time-steps (100 and 50 years ago and today). Old cadastral maps and aerial photographs were used to analyse past and present landscape patterns in 25 sites. Two plant diversity measures were investigated; total species richness and species density. During the last 100 years grassland area and connectivity have been reduced by about 90%. Present-day habitat area was positively related to total species richness in both habitats. There was also a relationship to habitat area 50 years ago for continuously grazed grasslands. Only present management was related to species density: continuously grazed grasslands had the highest species density. There were no relationships between grassland connectivity, present or past, and any diversity measure. We conclude that landscape history is not directly important for present-day plant diversity patterns in ordinary landscapes, although past grassland management is a prerequisite for the grassland habitats that can be found there today. It is important that studies are conducted, not only in very diverse landscapes, but also in managed landscapes in order to assess the effects of fragmentation on species.     

Comparison of multiplicative heterogeneous variance adjustment models for genetic evaluations

Two heterogeneous variance adjustment methods and two variance models were compared in a simulation study. The method used for heterogeneous variance adjustment in the Nordic test‐day model, which is a multiplicative method based on Meuwissen (J. Dairy Sci., 79, 1996, 310), was compared with a restricted multiplicative method where the fixed effects were not scaled. Both methods were tested with two different variance models, one with a herd‐year and the other with a herd‐year‐month random effect. The simulation study was built on two field data sets from Swedish Red dairy cattle herds. For both data sets, 200 herds with test‐day observations over a 12‐year period were sampled. For one data set, herds were sampled randomly, while for the other, each herd was required to have at least 10 first‐calving cows per year. The simulations supported the applicability of both methods and models, but the multiplicative mixed model was more sensitive in the case of small strata sizes. Estimation of variance components for the variance models resulted in different parameter estimates, depending on the applied heterogeneous variance adjustment method and variance model combination. Our analyses showed that the assumption of a first‐order autoregressive correlation structure between random‐effect levels is reasonable when within‐herd heterogeneity is modelled by year classes, but less appropriate for within‐herd heterogeneity by month classes. Of the studied alternatives, the multiplicative method and a variance model with a random herd‐year effect were found most suitable for the Nordic test‐day model for dairy cattle evaluation.     

Lipophilic extractives in different tree fractions and forestry assortments of Pinus sylvestris due for thinning or final cutting

The objectives were to determine the content and composition of lipophilic extractives, particularly fatty and resin acids, in three Scots pine trees from each of two stands in northern Sweden, one that was due for thinning and one due for final cutting. Extractives content of branches, needles, barks, stem discs from branch whorls, and sapwood and heartwood samples from various heights was measured. Fractions had very different concentrations and distributions of extractives due to differences in the composition of tissues. The needles had the highest total extractive concentration (around 150?kg/ton d.w.), followed by the branches, bark, timber from the final cut stand, and then the pulpwood and timber from the thinning stand. The final cut stand generally provided higher yields of extractives in assortments per hectare than the thinning stand; the difference was five-fold for timber, three-fold for whole trees, two-fold for branches, needles and bark and similar for pulpwood. This information on the content and composition of extractives in different tissues, and the dependence of these quantities on tree age could be used together with information on conventional stand data such as tree numbers and dimensions to guide the selection and management of feedstocks for biorefineries.     

Histology of uterine leiomyoma and occurrence in relation to reproductive activity in the Baltic gray seal (Halichoerus grypus)

A high prevalence of uterine leiomyoma has been reported in Baltic gray seals aged 15 years and above. Studies on Baltic seals during the 1970s revealed high tissue concentrations of the organochlorines bis(chlorophenyl)-1,1,1-trichloroethane (DDT) and polychlorinated biphenyls (PCBs), lowered reproduction rate, and pathologic changes. In the second half of the 1970s, decreases of PCB and DDT in Baltic biota occurred, and the prevalence of pregnancies in Baltic seals increased. Between 1975 and 1997, 53 Baltic gray seal females of age 15-40 years were found dead and sent to the Swedish Museum of Natural History. Seals were autopsied and 34/53 (64%) had uterine leiomyomas. Samples from 15 were sufficiently well preserved for histologic examination. Uterine leiomyomas were found most commonly in the uterine corpus but also were observed in the uterine horns, cervix, and vagina. Cut surfaces of the leiomyomas appeared as whorled white fibrous tissue. Histologically, spindle cells were arranged in a whorl-like pattern. The nuclei were rod-like and strikingly uniform in shape and size. Mitotic figures were rare. Immunohistochemical staining of the tumors showed a positive reaction to antibodies recognizing smooth muscle actin. Reproductively active gray seals have an ovarian corpus luteum or albicans for most of the year. In 22/34 (65%) gray seals with uterine leiomyomas, ovaries did not contain corpora. In gray seals without macroscopically detected uterine leiomyoma, ovaries from 6/19 (32%) seals had no corpora. It is possible that the development of leiomyoma in the seals is associated with organochlorines and the previous low reproductive activity.     

Detecting dominant landscape objects through multiple scales: An integration of object-specific methods and watershed segmentation

Complex systems, such as landscapes, are composed of different critical levels of organization where interactions are stronger within levels than among levels, and where each level operates at relatively distinct time and spatial scales. To detect significant features occurring at specific levels of organization in a landscape, two steps are required. First, a multiscale dataset must be generated from which these features can emerge. Second, a procedure must be developed to delineate individual image-objects and identify them as they change through scale. In this paper, we introduce a framework for the automatic definition of multiscale landscape features using object-specific techniques and marker-controlled watershed segmentation. By applying this framework to a high-resolution satellite scene, image-objects of varying size and shape can be delineated and studied individually at their characteristic scale of expression. This framework involves three main steps: 1) multiscale dataset generation using an object-specific analysis and upscaling technique, 2) marker-controlled watershed transformation to automatically delineate individual image-objects as they evolve through scale, and 3) landscape feature identification to assess the significance of these image-objects in terms of meaningful landscape features. This study was conducted on an agro-forested region in southwest Quebec, Canada, using IKONOS satellite data. Results show that image-objects tend to persist within one or two scale domains, and then suddenly disappear at the next, while new image-objects emerge at coarser scale domains. We suggest that these patterns are associated to sudden shifts in the entire image structure at certain scale domains, which may correspond to critical landscape thresholds.This revised version was published online in May 2005 with corrections to the Cover Date.     

Production of high yielding red raspberry long canes in a Northern climate

Techniques for the production of raspberry long canes with high yield potential were studied on a research station and in two commercial nurseries in South Norway. Potted ‘Glen Ample’ plants were grown in the open and in polyethylene greenhouses during two seasons in order to optimize cultural practices. Dates of propagation and transfer to the production sites were varied. Following cold storage from December to early June, the canes were tipped (cut) at 160 cm height and grown in open plastic tunnels in the fruiting season for the evaluation of growth and yield performance. Remarkable berry yields of 1.5–3.8 kg per plant (cane) were regularly achieved. When grown in the open, later starts than June 1 (June 15 and July 1) successively reduced yields. On the other hand, an earlier start involves risks of growth cessation due to low spring temperature. When grown in greenhouses, high yields were still possible when plants were transferred from propagation conditions as late as July 1, although optimal yields of nearly 4 kg per plant were obtained with transfer on June 15. In a year with unusually high summer temperatures, the yields of canes produced in the open and in greenhouses did not vary significantly, whereas in the second year with normal summer temperatures, canes produced in greenhouses consistently out-yielded those produced in the open by about 1 kg per cane. Regression analyses revealed that high yields were associated with fruiting cane architecture traits such as cane height, number and length of laterals, and a low proportion of dormant buds. The single most important component was lateral length which alone accounted for 82% of the yield variation. Since lateral lengths increased from the shoot tip towards the base, cane heights in excess of 2 m are required for the attainment of top yields as the uppermost nodes with short and low-yielding laterals then can be eliminated by tipping.     

Geography limits island small‐scale fishery production

Interacting social and ecological processes shape productivity and sustainability of island small‐scale fisheries (SSF). Understanding limits to productivity through historical catches help frame future expectations and management strategies, but SSF are dispersed and unaccounted, so long‐term standardized data are largely absent for such analyses. We analysed 40 years of trade statistics of a SSF product that enter international markets (sea cucumber) from 14 Pacific Island Countries and Territories (PICT) against response variables to test predictors of fishery production: (i) scale, (ii) productivity and (iii) socio‐economics. Combined production in PICT peaked over 20 years ago, driven by exploitation trends in Melanesia that accounted for 90% of all production since 1971. The size of island fisheries (as measured by total exports), and the duration and magnitude of fishery booms were most influenced by ungovernable environmental variables, in particular land area. The large and high islands of Melanesia sustained larger booms over longer periods than atoll nations. We hypothesize that land area is a proxy for land‐based nutrient availability and habitat diversity, and therefore the productivity of the shallow water areas where SSF are operating. PICT need to tailor management based on the intrinsic productivity of shallow inshore habitats: harvests from atoll nations will need to be smaller per unit area than at the high islands. Particularly countries with low productivity fisheries must consider the crucial economic “safety nets” that export SSF make up for dispersed island populations and incorporate them into broader development and island resilience strategies.     

Inheritance of multiple births in cattleHéridité des naissances gemellaires chez les bovinsVererbung von mehrlingsgeburten beim rindvieh

Records on approximately one million calvings were examined for presence of a gene with major effect on the frequency of multiple births. The records were summarized by parity of the cow and registration number of the cow's sire, and an overall age-corrected frequency of multiple births computed for daughters of each sire.The distribution of 876 progeny groups with more than 100 calvings showed no sign of discontinuity, and the same was true for 120 progeny groups with more than 1000 calvings. The daughters of one particular bull had 9.95% multiple births in about 6000 calvings. This bull left more than 80 sons which were used for artificial insemination. The sons ranged from less than one to more than 10% multiple births among their daughters, but no segregation was observed.Heritability estimates (on the binomial scale) ranged from 0.006 in parity 1 to about 0.04 in parities 3–5.Genetic correlations between incidence of multiple births in first and subsequent parities were estimated at 0.52–0.64, while those among parities 2–5 were from 0.70 to 0.84.     

Impacts of hypersaline water on the biotransformation and toxicity of fenthion on rainbow trout (Oncorhynchus mykiss), striped bass (Morone saxatilis X Morone chrysops) and tilapia (Oreochromis mossambicus)

Hypersaline water derived from agricultural practices primarily in arid landscapes can impact fisheries in streams receiving run-off from fields. Previous studies have indicated significant elevation in the toxicity of thio-ether pesticides by hypersaline water in certain species of euryhaline fish due to enhanced formation of sulfoxide metabolites which may be more toxic than the parent compounds. The objectives of this study were to evaluate the effects of salinity on the toxicity of the thio-ether organophosphate pesticide, fenthion in three species of euryhaline fish: rainbow trout (Oncorhynchus mykiss), striped bass (Morone saxatilis X Morone chrysops), tilapia (Oreochromis mossambicus) and determine whether a relationship was observed between toxicity and enantioselective sulfoxidation. Stereochemical formation and total sulfoxide formation did not mirror acute toxicity in the three species exposed in fresh or hypersaline conditions. Mortality of striped bass and rainbow trout due to fenthion exposure was enhanced by hypersaline treatments and a trend towards increased toxicity was observed in tilapia. In liver microsomes of rainbow trout, inhibition of cytochrome P450 (CYP) caused a respective 7- and 3-fold increase in sulfoxide formation in liver microsomes fresh and saltwater fish, and a significant increase in the formation of the (+)R-sulfoxide. CYP inhibition also caused a significant elevation of the (+)R-sulfoxide in freshwater striped bass, but not in hypersaline-treated bass. The results indicated contribution by CYP in the sulfoxidation of fenthion as well as the formation of other metabolites in all three species. In summary, hypersaline conditions impacted fenthion toxicity under conditions that appeared to be independent of fenthion sulfoxide formation indicating a much more complex mechanism of action for compounds with phosphorothioate and thio-ether structural features potentially involving multiple oxidative pathways.