Assessing water use and soil water balance of planted native tree species under strong water limitations in Northern Chile

Some forest plantations with native species are established in semiarid central Chile to compensate for industrial activities such as those of mining. Two of those operational forest plantations were monitored from age 1 to 3 years-old (2014–2016). Some plant attributes and soil volumetric water content (VWC) were monitored for eight native tree species (Acacia caven, Schinus polygamus, Porlieria chilensis, Lithraea caustica, Quillaja saponaria, Cryptocarya alba, Drimys winteri and Maytenus boaria), and a water balance model fitted to assess plant water use. Site preparation comprised planting holes of 40 cm?×?40 cm by 50 cm in depth dug with a backhoe. Substrate was removed and mixed with compost in proportion 70:30 before mixing it in the planting hole. Planting holes acted as water reservoirs over the study period with soil VWC generally increasing with soil depth being also less variable deeper than in the upper soil layers. The ratio of adaxial (upper leaf side) to abaxial (lower leaf side) stomatal conductance approximately followed a species gradient from xeric to mesic. Irrigation represented about 26% and 53% of the total water input for the sclerophyll and the D. winteri plantation, respectively. At the plant level (0.4?×?0.4 m), soil evaporation and transpiration of D. winteri (273 and 232 mm year^?1, equivalent to 43.7 and 37.1 L plant^?1, respectively) were about twofold the values for the sclerophyllous/malacophyllous plantation (138 and 128 mm year^?1, 22.1 and 20.5 L plant^?1, respectively). We suggest the water budget for the sclerophyll/malacophyllous plantation was tight but feasible to be adjusted while for D. winteri irrigation was excessive, could be drastically reduced, and suppressed altogether if planted in gullies. We believe water balance models and soil moisture content sensors could be used to better plan and manage irrigation frequency and amounts in compensation forest plantations in semiarid central Chile.     

Deposition of litter and nutrients in leaves and twigs in different plant communities of northeastern Mexico

Studies on litterfall and decomposition provide estimations of decomposition rates of different ecosystems.This is key information to understanding ecosystem dynamics and changes in a scenario of global warming.The objective of this research was to assess litterfall production,the potential deposition of macro and micronutrients through leaf and twig fall as well as macronutrient—use efficiency in three forest ecosystems at different altitudes: a pine forest mixed with deciduous species(S1); a Quercus spp.forest(S2); and,a Tamaulipan thornscrub forest(S3).Total annual litterfall deposition was 594,742 and 533 g m~(-2) for S1,S2 and S3.Leaf litter was higher (68%) than twigs(18%),reproductive structures(8%) or miscellaneous material(6%).Micronutrient leaf deposition was higher for Fe followed by Mn,Zn and Cu.Macronutrient leaf deposition was higher for Ca followed by K,Mg and P.Even though P deposition in leaves and twigs was lower than other macronutrients,its nutrient use efficiency was higher than Ca,Mg or K.Altitude and species composition determine litter and nutrient deposition,with higher values at mid-altitudes(550 m).Altitude is an important factor to consider when analyzing litter production as well as nutrient deposition as shown in this study.Litter production and nutrient deposition are expected to change in a scenario of global warming.     

Below-ground hydraulic constraints during drought-induced decline in Scots pine

Key message

Below-crown hydraulic resistance, a proxy for below-ground hydraulic resistance, increased during drought in Scots pine, but larger increases were not associated to drought-induced defoliation. Accounting for variable below-ground hydraulic conductance in response to drought may be needed for accurate predictions of forest water fluxes and drought responses in xeric forests.

Context

Hydraulic deterioration is an important trigger of drought-induced tree mortality. However, the role of below-ground hydraulic constraints remains largely unknown.

Aims

We investigated the association between drought-induced defoliation and seasonal dynamics of below-crown hydraulic resistance (a proxy for below-ground hydraulic resistance), associated to variations in water supply and demand in a field population of Scots pine (Pinus sylvestris L.)

Methods

Below-crown hydraulic resistance (r_bc) of defoliated and non-defoliated pines was obtained from the relationship between maximum leaf-specific sap flow rates and maximum stem pressure difference estimated from xylem radius variations. The percent contribution of r_bc to whole-tree hydraulic resistance (%r_bc) was calculated by comparing stem water potential variations with the water potential difference between the leaves and the soil.

Results

r_bc and %r_bc increased with drought in both defoliated and non-defoliated pines. However, non-defoliated trees showed larger increases in r_bc between spring and summer. The difference between defoliation classes is unexplained by differences in root embolism, and it is possibly related to seasonal changes in other properties of the roots and the soil-root interface.

Conclusion

Our results highlight the importance of increasing below-ground hydraulic constraints during summer drought but do not clearly link drought-induced defoliation with severe below-ground hydraulic impairment in Scots pine.

     

Host plant use by two distinct lineages of the tomato red spider mite, <Emphasis Type="Italic">Tetranychus evansi</Emphasis>, differing in their distribution range

The tomato red spider mite, Tetranychus evansi, is an emerging pest of solanaceous crops. Two distinct genetic lineages (I and II) have been identified, lineage I having a much wider geographic distribution than lineage II. This has been attributed to differences in cold hardiness that make lineage I better adapted to colonize the coldest parts of the invaded area. However, other factors such as the ability to exploit different hosts may also be involved. In this work, we compared the performance of the Nice (lineage I) and Perpignan (lineage II) strains of T. evansi on two frequent host plants for this species: black nightshade, Solanum nigrum, and cultivated tomato, S. lycopersicum. In general, Nice strain mites performed better (higher fecundity, lower offspring mortality, bigger egg size and lower percentage of males) than Perpignan strain mites when both: (1) they were reared and tested on the same host plant (S. lycopersicum or S. nigrum); and (2) when shifted from S. nigrum to S. lycopersicum and vice versa. Digestive proteases showed also higher expression in Nice strain mites than in Perpignan strain mites, independently of their plant host, potentially reflecting a more efficient proteolytic digestion of plant proteins. However, no differences in detoxification enzyme (P450, esterases and glutathione S-transferases) activities were found when the two strains were compared. In conclusion, our results demonstrate that Nice strain mites exhibited life history traits leading to higher fitness on two different hosts, which may be related with the higher invasive potential and outbreak risks of mites from lineage I.     

A cost-effective canopy temperature measurement system for precision agriculture: a case study on sugar beet

Increasing agricultural efficiency in a sustainable manner will contribute to feed a growing population under limited land, nutrient and water resources. Water scarcity and the increasing social concern for this resource are already requiring more sophisticated irrigation and decision-support systems. To address the heterogeneity in crop water status in a commercial field, precision irrigation requires accurate information about crops (e.g., crop water status), soil (e.g., moisture content) and weather (e.g., wind speed and vapor pressure deficit). Numerous studies have shown that plant canopy temperature can be used to derive reliable plant water stress indicators, thus making it a promising tool for irrigation water management. However, efficient and cost-effective measurement techniques are still lacking. This paper assesses the potential of infrared thermometry and thermal imaging for monitoring plant water stress in a commercial sugar beet field by comparing canopy temperature data acquired from a conventional thermal camera with an inexpensive infrared sensor, both mounted on a rotary-wing unmanned aerial vehicle (UAV). Measurements were taken at various phenological stages of the sugar beet growing season. Laboratory tests were performed to determine the key features for accurate temperature measurements and flight altitude. Experiments were conducted in 2014 and 2015 in experimental and commercial sugar beet fields in Southwestern Spain to (i) develop an affordable infrared temperature system suitable for mounting on a UAV to obtain thermal information, (ii) compare sugar beet canopy temperature measurements collected with the low-cost platform with those obtained from a conventional thermal camera, both mounted on a rotary-wing UAV, (iii) identify the factors that will limit the use of the low-cost system to derive temperature-based water stress indices. To accomplish these objectives, well-watered and deficit irrigated plots were established. Results indicated that the lightweight canopy temperature system was robust and reliable, although there were some constraints related to weather conditions and delimitation of the area covered by the infrared sensor.     

Prognostic impact of neoadjuvant aglepristone treatment in clinicopathological parameters of progesterone receptor‐positive canine mammary carcinomas

Neoadjuvant treatment of canine mammary carcinomas with the progesterone receptor (PR) antagonist aglepristone has a PR expression‐related inhibiting effect on proliferation index (PI). The aim of this study was to evaluate the effect of the treatment in the disease‐free period (DFP) and overall survival (OS) of canine mammary carcinomas. Fifty female dogs with mammary carcinomas were treated with aglepristone (n = 34) or oil vehicle (n = 16) before surgery (day 15). PR expression and PI were analysed by immunohistochemistry in samples taken at days 1 and 15. Epidemiological and clinicopathological data were assessed. DFP and OS data were retrieved every 4–6 months for at least 24 months after surgery. Aglepristone treatment increased DFP of animals bearing PR+ tumours with size smaller than 3 cm, complex and mixed tumours, with histologic grades I and II, and with PI ≤ 10%. Although further studies are necessary, current evidence points to treatment with aglepristone as useful for the management of canine mammary tumours.     

Bioavailability of Metals at a Southeastern Brazilian Coastal Area of High Environmental Concern Under Anthropic Influence: Evaluation Using Transplanted Bivalves (<Emphasis Type="Italic">Nodipecten nodosus</Emphasis>) and the DGT Technique

Metals are commonly determined in aquatic organisms, primarily using bivalves to provide important data on their bioavailability. The technique of diffusive gradients in thin films (DGTs) has also been employed to assess the concentration of metals in freshwater and marine environments, determining their lability. The present work evaluated and compared the labile and bioavailable concentrations of Cd, Co, Cu, Mn, Ni and Pb in seawater from Ilha Grande Bay, RJ, using DGT and transplanted bivalves (Nodipecten nodosus), respectively. The scallops and DGTs were immersed in water at three sampling locations within the bay from July to September 2012 (winter campaign) and from December 2012 to February 2013 (summer campaign). The metals were determined by inductively coupled plasma-mass spectrometry (ICP-MS) and optical emission spectrometry (ICP-OES). DGT technique was successfully used to determine the concentrations of metals in waters, except for Pb when short deployment times were used. All metals were determined using transplanted bivalves (N. nodosus), but pre-exposure to Cd was evident, which made the interpretation of the data for this analyte difficult. The data on metal lability in Ilha Grande Bay waters obtained from the DGT technique were correlated with the metal bioavailability determined in the soft tissues of the transplanted N. nodosus for Co, Cu, Mn, Ni and Pb. This is the first evaluation of this type for this area of high environmental concern. Both techniques revealed that Náutico was the location with the highest concentration of metals in the study area.     

Viability of Introducing Payments for the Collection of Wild Forest Mushrooms in Catalonia (North-East Spain)

Wild mushrooms are among the most valuable non-wood forest products in the world, and mushroom picking activities are well developed in many countries. Recent studies have demonstrated important links between forest management options and the productivity of mushrooms. Furthermore, there is evidence that the optimal forest management oriented at maximizing joint revenues from timber and mushrooms can lead to higher profits than the traditional timber-oriented management. The precondition for such management, however, is that forest owners derive benefits from mushrooms produced in their forests. In this paper, we discuss the feasibility of implementing payments for mushroom harvesting in Catalonia, North East Spain. As in many other European regions, mushroom picking in Catalonia is a long-standing tradition, which has been practiced with negligible limitations for centuries. The rising popularity of this activity in the last decades, however, has caused forest owners to voice concerns about the sustainability of this activity and about the impact it has on the private forest property. We document the results of a public opinion survey and contrast them with the issues emergent from forest owners’ interviews about the regulation of mushroom picking activities. Our results show that mushroom pickers support the idea of introducing payments for mushroom harvesting. Based on the survey and interview results, we also discuss the design aspects of payments for mushroom picking and articulate the key issues in their implementation.