Ovulation induction in polycystic ovary syndrome Tanbo, Tom; Mellembakken, Jan; Bjercke, Sverre ...
Acta obstetricia et gynecologica Scandinavica,
October 2018, Volume:
97, Issue:
10
Journal Article
Peer reviewed
Open access
The objective of this narrative review was to suggest a rational order of treatment choices in anovulatory women with polycystic ovary syndrome (PCOS), for whom a multitude of treatment options ...exist. In obese/overweight women with PCOS the importance of weight reduction should be stressed. Inositol, a dietary supplement with a documented effect on ovulation and without adverse effects in the doses recommended, may be suggested. Additional first‐line medical alternatives include insulin sensitizers, selective estrogen receptor modulators, and aromatase inhibitors. Of these, the aromatase inhibitor letrozole and the combination of clomiphene citrate and metformin have the highest rates of ovulation and live birth. Second‐line treatments are ovarian electrocautery and low‐dose follicle‐stimulating hormone stimulation. Controlled ovarian stimulation with in vitro fertilization, should be considered the last option as it carries a significant risk of ovarian hyperstimulation syndrome in patients with PCOS.
Nitrogen (N) availability plays multiple roles in the boreal landscape, as a limiting nutrient to forest growth, determinant of terrestrial biodiversity, and agent of eutrophication in aquatic ...ecosystems. We review existing research on forest N dynamics in northern landscapes and address the effects of management and environmental change on internal cycling and export. Current research foci include resolving the nutritional importance of different N forms to trees and establishing how treemycorrhizal relationships influence N limitation. In addition, understanding how forest responses to external N inputs are mediated by above- and belowground ecosystem compartments remains an important challenge. Finally, forestry generates a mosaic of successional patches in managed forest landscapes, with differing levels of N input, biological demand, and hydrological loss. The balance among these processes influences the temporal patterns of stream water chemistry and the long-term viability of forest growth. Ultimately, managing forests to keep pace with increasing demands for biomass production, while minimizing environmental degradation, will require multi-scale and interdisciplinary perspectives on landscape N dynamics.
Forest soils in Northern Europe are generally trafficked by forest machinery on several occasions during a forest rotation. This may create ruts (wheel tracks), which could increase sediment ...transport to nearby surface water, reduce recreational value, and affect tree growth. It is therefore important to reduce soil disturbance during off-road forest transportation. In this study, rut depth was measured following forwarder traffic on study plots located along four harvested till hillslopes in Northern Sweden with drier soil conditions uphill and wet conditions downhill. The treatments included driving 1) using no ground protection, 2) on logging residue (on average, 38–50 kg m–2) and 3) on logging mats measuring 5×1×0.2 m. The hillslopes contain areas with a high content of boulders, stones, and gravel as well as areas with a significant content of silt. Six passes with a laden forwarder with four bogie tracks were performed. On the plots with ground protection, the application of logging residue and the application and removal of logging mats necessitated additional passes. Rut depth was measured using two methods: 1) as the difference in elevation between the interpolated original soil surface and the surface of the rut using GNSS positioning (Global Navigation Satellite Systems), and 2) manually with a folding rule from an aluminium profile, placed across the rut, to the bottom of the rut. The two methods generally gave similar results. Driving without ground protection in the upper part of the hillslopes generated ruts with depths <0.2 m. Here, the rut depth was probably modified by the high content of boulders and stones in the upper soil and drier soil conditions. In the lower part of the hillslopes, the mean rut depth ranged from 0.21 to 0.34 m. With a few exceptions, driving on logging residue or logging mats prevented exposure of mineral soil along the entire hillslope. Soil disturbance can thus be reduced by acknowledging the onsite variability in ground conditions and considering the need for ground protection when planning forest operations.
This study focuses on avoiding negative effects on surface waters using new techniques for identifying wet areas near surface waters. This would aid planning and designing of forest buffer zones and ...off-road forestry traffic. The temporal variability in the geographical distribution of the stream network renders this type of planning difficult. A field study was performed in the 68 km2 Krycklan Catchment to illustrate the variability of a boreal stream network. The perennial stream length was 140 km while the stream length during high-flow conditions was 630 km. Comparing the field-measured stream network to the network presented on current maps showed that 58% of the perennial and 76% of the fully expanded network was missing on current maps. Similarly, cartographic depth-to-water maps showed that associated wet soils constituted 5% of the productive forest land during baseflow and 25% during high flow. Using a new technique, maps can be generated that indicate full stream networks, as well as seasonally active streams and associated wet soils, thus, forestry planning can be performed more efficiently and impacts on surface waters can be reduced.
Nitrogen (N) fertilization and soil scarification are common measures used in commercial forestry in the boreal zone. This study was performed to investigate how previous N fertilization in two ...N-limited Scots pine (Pinus sylvestris L.) stands affected the soil-solution chemistry after final felling and also to determine the effect of subsequent soil scarification. Nitrogen had been applied to study plots at different intervals, resulting in total applications of 0, 450, 900, or 1800 kg N·haâ»Â¹. Soil-solution samples were collected before and after whole-tree harvesting of the P. sylvestris stand, from undisturbed soil and also after harvesting from soil below furrows, tilts, and areas between furrows created by disc trenching. After harvesting, the K⺠concentration was lower at higher N fertilization intensities. No overall effect on the N concentrations was detected. Electrical conductivity and the concentrations of Naâº, Kâº, Mg²âº, Ca²âº, Clâ», NOââ»âN, total N, and total C were all affected by soil scarification. The highest concentrations of these variables were found below tilts and the lowest concentrations below furrows. The experiment was repeated, at a lower monitoring intensity, at a site where the previous total N application amounted to 0 and 450 kg N·haâ»Â¹. Here the NOââ»âN concentration responded to disc trenching in a similar way to that observed in the main experiment. The study shows that previous N fertilization of N-limited forest does not necessarily affect the soil-solution chemistry significantly after whole-tree harvesting.
Adaptation to climate change in forestry has become a growing concern, in part due to the impact of storms and other events that have raised the awareness of such risks amongst forest owners. Sweden ...is one of Europe’s most densely-forested countries, with this sector playing a major role economically. However adaptation has, to a large extent, been limited to the provision of recommendations to forest managers, most of which have only been partially implemented. This paper summarizes research with direct implications for adaptation to climate change within the forestry sector in Sweden. The focus is based in particular on providing examples of adaptations that illustrate the specific Swedish orientation to adaptation, in line with its relatively intensive forest management system. The paper thus illustrates a specific Swedish orientation to adaptation through active management, which can be contrasted with approaches to adaptation in other forestry systems, in particular those with limited management or management based on maintaining natural forests in particular.
There is increasing evidence that forests and forest soil contribute to the signature of chlorine composition in water bodies. However, little is known about the potential effects of land management ...activities on chlorine biogeochemistry. This study examines the effects of previous nitrogen addition on chlorine chemistry in a Pinus sylvestris L. forest located in south-central Sweden (60°00′N, 13°43′E). Repeated addition of nitrogen to study plots over a 20-year period resulted in total additions of 0, 450 and 900 kg N ha⁻¹. Soil samples were collected before harvesting, and soil solution and biomass were sampled following final felling. Contrary to previous findings, we found no clear evidence that previous addition of nitrogen had hampered the formation of organic chlorine in the organic soil layer. We suggest that the effects of nitrogen addition on chlorination processes are not seen in the surface soil, but are instead manifested in the migration of organic matter in the mineral soil. Soil organic matter from the E-horizon had a lower chlorination degree in the nitrogen-amended plots than in the control plots. In addition, we observed lower Cl⁻ levels in the seedling needles following high nitrogen fertilization (900 N) than in 450 N or control. These results add on the importance of studying chlorine dynamics with focus on what chlorinated soil organic matter can be resistant to degradation compared to average soil organic matter and what can be leached as a result of harvesting and available for vegetation.
Additions of nutrients, faster growing tree varieties, more intense harvest practices, and a changing climate all have the potential to increase forest production in Sweden, thereby mitigating ...climate change through carbon sequestration and fossil fuel substitution. However, the effects of management strategies for increased biomass production on soil resources and water quality at landscape scales are inadequately understood. Key knowledge gaps also remain regarding the sustainability of shorter rotation periods and more intensive biomass harvests. This includes effects of fertilization on the long-term weathering and supply of base cations and the consequences of changing mineral availability for future forest production. Furthermore, because soils and surface waters are closely connected, management efforts in the terrestrial landscape will potentially have consequences for water quality and the ecology of streams, rivers, and lakes. Here, we review and discuss some of the most pertinent questions related to how increased forest biomass production in Sweden could affect soils and surface waters, and how contemporary forestry goals can be met while minimizing the loss of other ecosystem services. We suggest that the development of management plans to promote the sustainable use of soil resources and water quality, while maximizing biomass production, will require a holistic ecosystem approach that is placed within a broader landscape perspective.
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