Perspectives in dryland restoration: approaches for climate change adaptation

Reforestation efforts in dryland ecosystems frequently encounter drought and limited soil productivity, although both factors usually interact synergistically to worsen water stress for outplanted seedlings. Land degradation in drylands (e.g. desertification) usually reduces soil productivity and, especially, soil water availability. In dry sub-humid regions, forest fires constitute a major disturbance affecting ecosystem dynamics and reforestation planning. Climate change projections indicate an increase of drought and more severe fire regime in many dryland regions of the world. In this context, the main target of plantation technology development is to overcome transplant shock and likely adverse periods, and in drylands this is mostly related to water limitations. In this paper, we discuss some selected steps that we consider critical for improving success in outplanting woody plants, both under current and projected climate change conditions including: (1) Plant species selection, (2) Improved nursery techniques, and (3) Improved planting techniques. The number of plant species used in reforestation is increasing rapidly, moving from a reduced set of well-known, easy-to-grow, widely used species, to a large variety of promising native species. Available technologies allow for reintroducing native plants and recovering critical ecosystem functions for many degraded drylands. However, climate change projections introduce large uncertainties about the sustainability of current reforestation practices. To cope with these uncertainties, adaptive restoration approaches are suggested, on the basis of improved plant quality, improved techniques for optimizing rain use efficiency in plantations, and exploring native plant species, including provenances and genotypes, for their resilience to fire and water use efficiency.     

Effects of cortisol on pregnancy rate and corpus luteum function in heifers: an in vivo study

To determine whether glucocorticoids affect the function of the bovine corpus luteum (CL) during the estrous cycle and early pregnancy, we examined the effects of exogenous cortisol or reduced endogenous cortisol on the secretion of progesterone (P4) and on pregnancy rate. In preliminary experiments, doses of cortisol and metyrapone (an inhibitor of cortisol synthesis) were established (n=33). Cortisol in effective doses of 10 mg blocked tumor necrosis factor-induced prostaglandin F(2α) secretion as measured by its metabolite (PGFM) concentrations in the blood. Metyrapone in effective doses of 500 mg increased the P4 concentration. Thus, both reagents were then intravaginally applied in the chosen doses daily from Day 15 to 18 after estrus (Day 0) in noninseminated heifers (n=18) or after artificial insemination (n=36). Pregnancy was confirmed by transrectal ultrasonography between Days 28-30 after insemination. Plasma concentrations of P4 were lower in cortisol-treated heifers than in control heifers on Days 17 and 18 of the estrous cycle (P<0.05). However, the interestrus intervals were not different between control and cortisol-treated animals (P>0.05). Moreover, metyrapone increased P4 and prolonged the CL lifespan in comparison to control animals (P<0.05). Interestingly, in inseminated heifers, cortisol increased the pregnancy rate (75%) compared with control animals (58%), whereas metyrapone reduced the pregnancy rate to 16.7% (P<0.05). The overall results suggest that cortisol, depending on the physiological status of heifers (pregnant vs. nonpregnant), modulates CL function by influencing P4 secretion. Cortisol may have a positive influence on CL function during early pregnancy, leading to support of embryo implantation and resulting in higher rates of pregnancy in heifers.     

Magnetic resonance imaging of canine mast cell tumors

Mast cell tumors (MCT) are the most common cutaneous tumors in dogs. Our purpose was to describe the magnetic resonance (MR) imaging characteristics of cutaneous MCT and to identify imaging characteristics that allow differentiation of metastatic from normal lymph nodes. Eight dogs with a total of nineMCT were imaged as were their presumed draining and associated contralateral lymph nodes. The signal intensity of tumors and lymph nodes was compared to adjacent musculature. On T2-W images, 7/9 MCT were hyperintense to muscle and 2/9 were isointense. On T1-W images, 8/9 MCT were isointense and 1/9 were mildly hypointense. All tumors were strongly contrast enhancing; 5/9 were homogeneous and 4/9 heterogeneous in their enhancement patterns. Six lymph node pairs were included in the evaluation (five sentinel lymph nodes with metastases, one without, and six contralateral lymph nodes). Metastatic lymph nodes were significantly larger than their contralateral lymph nodes (P = 0.039). All lymph nodes were isointense on T1-W images and hyperintense on T2-W images. 5/5 metastatic and 2/7 normal lymph nodes were heterogeneously T2-hyperintense. All lymph nodes were moderately to strongly contrast enhancing. 4/5 metastatic and 2/7 normal lymph nodes had heterogeneous enhancement patterns. While heterogeneity was more common in metastatic than in normal lymph nodes, this difference was not significant (P = 0.058 for T2-W images; P = 0.234 for postcontrast images). MR imaging may be useful in the presurgical evaluation and clinical staging of cutaneous MCT.     

Effect of oxytocin infusion on luteal blood flow and progesterone secretion in dairy cattle

The objective of this study was to investigate the effects of oxytocin infusion on corpus luteum (CL) function during early to mid-diestrus by measuring luteal size (LS) and luteal blood flow (LBF) along with plasma levels of progesterone (P4) and prostaglandin metabolites (13,14-dihydro-15-keto-prostaglandin F_2α, PGFM). On day (D) 7 of the estrus cycle (D1 = ovulation), seven cows received 100 IU of oxytocin (OXY) or placebo (PL) following a Latin square design. LS and LBF increased in both groups over time and no differences were observed between the groups. PGFM did not differ either within the groups over time or between the groups at any time point. P4 of the OXY group was higher compared to that of the the PL group 360 min after the infusion (p = 0.01) and tended to be higher at the time points 450 min, 48 h, and 72 h (all p = 0.08). Results from this study support the hypothesis that OXY is not directly involved in the mechanism(s) governing blood flow of the CL and has no remarkable effects either on luteal size or P4 and PGFM plasma levels. Further investigation is needed to elucidate the role of OXY in CL blood flow during early and late luteal phases.     

Evaluation of the flammability of gorse (<Emphasis Type="Italic">Ulex europaeus</Emphasis> L.) managed by prescribed burning

• Introduction  

The abandonment of rural areas has led to an increase of the fire-prone European gorse (Ulex europaeus L.) communities in some regions, where prescribed burning is a technique applied to control them. Understanding flammability changes after treatments is crucial for the sustainable use of fire.     

Thinning increases cone production of stone pine (Pinus pinea L.) stands in the Northern Plateau (Spain)

Context

Edible stone pine (Pinus pinea L.) nut is a forest product which provides the highest incomes to the owners of stone pine forests.

Aim

The objective of this work is to evaluate the effect of first thinning on growth and cone production in an artificially regenerated stand in order to determine optimum intensity.

Methods

A thinning trial was installed in 2004 to compare two thinning regimes (heavy and moderate) and a control treatment. From 2004 to 2012, six inventories of forest attributes were carried out, and the cone crop was harvested annually. We evaluated the effect of thinnings on growth using repeated measures analysis of variance with a mixed model approach. With regards to cone production, we first estimated the probability of finding cones in a tree by applying a generalized mixed model and then estimated cone production by using a mixed model, including climatic variables.

Results

We found that thinning had a positive influence on tree diameter increment. Thinning increased the probability of finding cones and cone production. However, significant differences between heavy and moderate thinnings were not found.

Conclusion

We recommend early silvicultural treatments in stone pine stands to favor the development of trees and larger edible pine nut production.     

Coupling hysteresis analysis with sediment and hydrological connectivity in three agricultural catchments in Navarre,Spain

Purpose

Rain storm events mobilise large proportions of fine sediments in catchment systems. Sediments from agricultural catchments are often adsorbed by nutrients, heavy metals and other (in)organic pollutants that may impact downstream environments. To mitigate erosion, sediment transport and associated pollutant transport, it is crucial to know the origin of the sediment that is found in the drainage system, and therefore, it is important to understand catchment sediment dynamics throughout the continuity of runoff events.

Materials and methods

To assess the impact of the state of a catchment on the transport of fine suspended sediment to catchment outlets, an algorithm has been developed which classifies rain storm events into simple (clockwise, counter-clockwise) and compound (figure-of-eight; complex) events. This algorithm is the first tool that uses all available discharge and suspended sediment data and analyses these data automatically. A total of 797 runoff events from three experimental watersheds in Navarre (Spain) were analysed with the help of long-term, high-resolution discharge and sediment data that was collected between 2000 and 2014.

Results and discussion

Morphological complexity and in-stream vegetation structures acted as disconnecting landscape features which caused storage of sediment along the transport cascade. The occurrence of sediment storage along transport paths was therefore responsible for clockwise hysteresis due to the availability of in-stream sediment which could cause the “first flush” affect. Conversely, the catchment with steeper channel gradients and a lower stream density showed much more counter-clockwise hysteresis due to better downstream and lateral surface hydrological connectivity. In this research, hydrological connectivity is defined as the actual and potential transfer paths in a catchment. The classification of event SSC-Q hysteresis provided a seasonal benchmark value to which catchment managers can compare runoff events in order to understand the origin and locations of suspended sediment in the catchment.

Conclusions

A new algorithm uses all available discharge and suspended sediment data to assess catchment sediment dynamics. From these analyses, the catchment connectivity can be assessed which is useful to develop catchment land management.

     

Multivariate statistical analysis of mass spectra as a tool for the classification of the main humic substances according to their structural and conformational features

The aim of this work is to explore the suitability of the complementary use of mass spectra and the corresponding statistical analysis (principal components-Pareto analysis (PCA) and discriminant analysis (DA)) of these spectra to differentiate diverse humic samples as a function of their structural and conformational features. To this end, the mass spectra of humic samples belonging to the main humic fraction types (gray humic acid, brown humic acid, and fulvic acid) were obtained by electrospray ionization mass spectrometry (ESI-MS). The results obtained showed that the application of PCA yielded a clear separation between blanks and humic samples. However, a clear differentiation among the humic fraction types was not achieved. The DA of PCA data, however, yielded a clear separation among the humic substances (HS) samples belonging to each HS fraction type considered: gray humic acids, brown humic acids, and fulvic acids. These results showed that the mass spectra of each humic sample include characteristic mass/charge (m/z) distribution values that can be considered as a "fingerprint" representative of its specific structural features. Our results also indicate that, although the m/z values principally corresponded to single-charged ions, we cannot identify these molecular weight distributions with those of humic samples, since sample molecular fragmentation, as well as partial molecular ionization, cannot be ruled out under our experimental and instrumental conditions.     

Diurnal and seasonal water variations of temperature,pH, redox potential and conductivity in gnammas (weathering pits): Implications for chemical weathering

A gnamma or weathering pit is a small-sized cavity sculpted into solid rock which refills with rainwater. This study describes the main hydrological processes in gnammas and the underlying chemical interactions with the environment. Four gnammas developed in a granite tor from central Spain were chosen for monitoring and studying the dynamics of the gnamma–water system. Parameters monitored were air and water temperature, pH, ORP (redox potential), and conductivity. These measurements describe the system dynamics, without the need for special sampling or other potential interferences under low water volumes. Additionally, chemical analyses were carried out to contrast the chemical properties with the chemical composition. As a consequence of water volumes less than 100 L, daily fluctuations tended to cause the largest amplitude changes. Photosynthesis and respiration/putrefaction processes in the gnamma are responsible for daily pH fluctuations up to 4 units, with pH values often greater than 9. ORP generally alternates from positive to negative values as the solution oscillates diurnally between basic and acidic conditions. Conductivity values ∼ 10 μS/cm occur most of the year, with only minor daily oscillations. During dry periods, conductivity increases significantly with maximum values > 400 μS/cm. These high conductivity values reflect atmospheric inputs by summer rainstorms after prolonged dry periods. Therefore, conductivity does not relate directly with chemical species dissolved from the host rock. Silica was the main weathering product of granite dissolution during the year, with highest concentrations (> 200 ppm) in the rainy season. Low Si values measured during the dry season are in accordance with observed precipitation of amorphous silica within the gnamma. Seasonal variations in concentration are also present in Al and Fe as a response to ORP variations and evaporative dynamics, causing mineral dissolution and new mineral precipitation during the year. Relations among the measured parameters are influenced by several factors, including biological processes, temperature effects and water level variations. Factors such as large pH oscillations, basic pH values, acids from biological activity, and alkali cations all increase silicate solubility, thus favoring granite dissolution. Overflow of water during the winter, when the water is chemically enriched, is an effective mechanism to remove weathering products.