Cold-dry Conditions Research Articles

Tree growth decline to warm-wet conditions in boreal forests is linked to stand density

Warm-wet climatic conditions are widely regarded as conducive to remarkable tree growth, alleviating climatic pressures. However, the notable decline in tree growth observed in the southern edge of boreal forests has heightened concerns over the spatial-temporal dynamics of forest decline. Currently, attaining a comprehensive grasp of the underlying patterns and their propelling factors remains a formidable challenge. We collected tree ring samples from a network of 50 sites across the Greater Xing’an Mountains. These samples were subsequently grouped into two distinct clusters, designated as Groups A and B. The percentage change of growth (GC, %) and the proportion of declining sites were utilized to assess forest decline. The decline in tree growth within Larix gmelinii forests exhibits significant regional variation, accompanied by temporal fluctuations even within a given region. Group A exhibited a pronounced increase in frequency (59.26%) of occurrences and encountered more severe declines (21.65%) in tree growth subsequent to the 1990s, contrasting sharply with Group B, which observed lower frequencies (20.00%) and relatively less severe declines (21.02%) prior to the 1980s. The primary impetus underlying the opposite radial growth increments observed in Larix gmelinii trees from the interplay between their differential response to temperatures and wetter climatic conditions, which is significantly influenced by varying stand densities. In cold-dry conditions, low-density forests may experience soil water freezing, exacerbating drought conditions and thereby inhibiting tree growth, in Group A. Trees growth in high-density stands is enhanced under warm-wet conditions, in Group B. These results provide new insights into the variability at the southern edge of the boreal forest biome with different responses to density and climate.

Derivation of seed viability constants (KE and CW) and prediction of longevity of Solanum aethiopicum seeds

The seed viability equation uses species viability constants to predict seed longevity under different storage conditions. There are already established universal values of constants that account for the effect of temperature on seed longevity (CH and CQ) which can be applied to different crop species. However, constants accounting for the effect of seed moisture (CW) and genotype (KE) are species-specific. This study aimed to derive viability constants and predict seed longevity for African eggplant (Solanum aethiopicum) under genebank conditions. The seeds were subjected to experimental storage at 40°C and different seed moisture contents (6, 8, 10 and 12%) for 120 days to derive survival curves and hence, CW and KE. CW and KE values for S. aethiopicum were 3.32 and 7.4978, respectively. The validation of the derived constants show that they can be used to predict seed longevity of other seed lots within the same species. The genebank curators and other commercial seed technologists may be able to accurately predict longevity of African eggplant seeds under cold dry storage conditions using the improved viability equation and the constants established in this research.

Determination of Paleoenvironmental Changes by Using δ13C, 14C Dating and Rb/Sr Ratio in Critical Karst Area of Yunnan-Guizhou Plateau, Southwestern China

Paleosols preserve archives of vegetation history, environmental changes, and sedimentary systems. The changes in vegetation history and environmental conditions in karst areas of the Yunnan–Guizhou plateau of southwestern China since the late Pleistocene were analyzed using δ13C, 14C and the Rb/Sr ratio. Our δ13C results reveal the coexistence of C3 and C4 plants (−10.91 to −30.45‰) in soil organic matter, something that is consistent with the present field vegetation assessment. The large vertical difference in the δ13C value (>4‰) is related to the cultivation of agricultural crops and to changes in environmental conditions. Furthermore, the variation in δ13C values was influenced by the summer monsoon climate of the Indian Ocean and east Asia. We found that total organic carbon (TOC) concentration decreased exponentially with soil depth, indicating high carbon loss. In addition, 14C apparent age of the soil profiles ranged from modern times to 20,605 (±63) years before the present (yrs. BP) and is positively correlated with soil depth. The combined results indicate that, since the late Pleistocene era, environmental conditions in the study area have changed intermittently on a scale of millennia from hot-humid to cold-dry conditions. We speculate that there may have been extreme climate events in the study area 14,750 years BP, which are marked by a drastic change in δ13C and in the Rb/Sr ratio.

Late Quaternary changes in moisture availability and weathering intensity on the central Tibetan Plateau indicated by chemical signatures of ostracod shells

High-resolution multi-proxy records from two lakes on the southern Tibetan Plateau, Nam Co and Tangra Yumco, are used to infer long-term variations in the Asian monsoon system with a novel set of ostracod shell chemistry proxies. We track the moisture evolution since the Last Glacial Maximum using the trace element, rare earth element (REE) and stable isotope composition of ostracod shells. The sediment records covering the past 18.8 cal. ka BP and 17.4 cal. ka BP, respectively, demonstrate the suitability of REEs as indicators of weathering intensity and thus hydrological changes and moisture sources in the catchment. In Nam Co, high concentrations of light REEs between 14 and 13 cal. ka BP suggest an increased drainage from the glaciated Nyainqêngtanglha Mountains in the south, pointing to meltwater input. REEs in ostracod shells therefore provide additional information on water sources critical for the interpretation of stable isotope records. Mg/Ca, Sr/Ca, and Ba/Ca ratios reflect salinity and thus changes in effective moisture. Asynchronous behavior of Mg/Ca, Sr/Ca, and Ba/Ca ratios are controlled by changes in dominance of precipitating carbonate minerals in the lake. Synchronous behavior reflects calcite precipitation, indicating low-Mg/Ca warm-wet conditions. Constantly low Sr/Ca ratios reflect aragonite precipitation, indicating high-Mg dry conditions. Increased Sr/Ca and Ba/Ca relative to Mg/Ca ratios show monohydrocalcite precipitation, indicating high-Mg/Ca cold-dry conditions. Furthermore, Fe/Ca, Mn/Ca and U/Ca ratios in ostracods reflect changes in oxygen saturation in lake bottom waters controlled by lake level and microbial activity. The paleoclimate histories reconstructed from Nam Co and Tangra Yumco show high similarity throughout the late Quaternary. We identified two major dry periods, corresponding to Heinrich 1 and the Younger Dryas, followed by strengthening in Indian summer monsoon precipitation. The early Holocene is characterized by a moisture maximum, reflecting abundant water supply by a strong ISM. A time-delayed shift to dry conditions occurred at 2.6 cal. ka BP at Tangra Yumco, and at 2 cal. ka BP at Nam Co, resulting in decreasing lake levels, caused by weakened monsoon intensity due to a southeastward migration of the ISM-Westerly boundary with an estimated velocity of approximately 600 m per year.

Global climate change drove terrestrial ecosystem evolution during the late Paleocene-middle Miocene in the Lanzhou Basin, northeast Tibetan Plateau

In this paper, we present organic carbon isotope records from continental sediments spanning the late Paleocene-middle Miocene (57.9–15.0 Ma) in the Lanzhou Basin, northeastern Tibetan Plateau to investigate terrestrial ecosystem-response to global climate change. The continuous sediment δ13CTOC values that we obtained range from −27.83‰ to −20.05‰. Combining these data with the sediment C/N ratios and n-alkane distribution, we infer that the major source of sediment organic matter was terrestrial C3 plants. Furthermore, we note that both sediment δ13CTOC and δ13Cn-alkanes values gradually become more positive from 57.9 to 26 Ma and then become relatively more negative from 26 to 15 Ma. These δ13C values vary closely with global temperature changes. We propose that global temperature controlled δ13C values with cooler conditions resulting in less rainfall in inland Asia, and vice versa. Therefore, mainly driven by the global temperature, the regional climate in the Lanzhou Basin gradually changed from warm-wet to cold-dry conditions during 57.9–26 Ma, and the climatic conditions became warmer and wetter again after 26 Ma. This long-sequence terrestrial ecologic environment study obtained from the northeast Tibetan Plateau powerfully demonstrates the first-order role of global climate in regulating the long-term evolution of regional environment.

Study of Apple Varieties in High-Density Plantation under Cold Dry Temperate Conditions of Kinnaur

The study was carried out to evaluate four apple varieties on different rootstocks under high-density plantations in the cold temperate region of Kinnaur for growth, yield and quality attributes. The experiment evaluated four apple varieties ‘Red Cap Valtod/MM 106’, ‘Red Velox/M9’, ‘Jeromine/M9’ and ‘Super Chief/MM 106’ planted at a spacing of 2.5×1.0 m2 in Randomized Block Design, with four replicates. From the evaluation of data on growth, floriculture and quality standards, it was clear that var. Jeromine/M9 followed by Red Velox/M9 has recorded better horticultural performance than other varieties studied. Among different varieties Red Velox/M9 recorded maximum shoot extension growth (22.65 cm), trunk girth (47.27 mm) and tree height (340.02 cm), tree spread (175.52 E-W and 181.68 cm N-S), number of fruit set tree-1 (41.85), fruit Breadth (78.90 mm), fruit weight (207.39 g fruit-1), TSS (10.11 °Brix), whereas, maximum fruit set (25.48%), fruit length (71.74 mm), yield (3.59 kg tree-1) and productivity (14.35 MT Hac-1) was recorded in cultivar Jeromine/M9. However, the maximum number of fruits tree-1 was observed in the variety Red Cap Vatod/MM 106. Variety, Red Velox /M9 was found to be superior for growth, flowering, yield and quality characteristics with good market potential under Kinnaur conditions.

Paleo-vegetation and environmental history of Natural Trap Cave based on pollen and carbon isotope analyses

Pollen and carbon isotope data from Natural Trap Cave provides insights into the environmental conditions of the Bighorn Basin, in north-central Wyoming, USA during the time intervals 151.1 to 132.2 cal ka BP, 51.8 to 17.4 cal ka BP, and 10.4 cal ka BP to present. Similarities between the buildup of the penultimate and last glacial maxima include abundant Artemisia, Amaranthaceae, Asteraceae, and Poaceae pollen, which, when combined with high δ13C values (>−25.0‰) and low plant discrimination values (18.0–19.0‰) from sedimentary organic matter, indicate steppe-like, cold-dry conditions. Between 151 and 142.5 cal ka BP, abundant Poaceae associated with much lower δ13C values (−28.0‰ to −26.0‰) and higher plant discrimination values (19.0‰–21.0‰) could be indicative of relatively wet summers. Similarly, after 25 cal ka BP increases in Poaceae may indicate wet conditions during the growing season. Holocene conditions differ from the earlier sections of the record, with greater arboreal pollen abundance (i.e., Pinus), consistent with woodland expansion in the region. Carbon isotope data from sedimentary organic matter show the Holocene was more humid than the glacial conditions of the late Pleistocene. This is especially clear at the start of the Holocene when a large negative carbon isotope excursion (CIE, < −28.0‰) occurred, providing a distinct chemostratigraphic marker defining the Pleistocene-Holocene boundary within these cave sediments. The association of this CIE with a pronounced spike in Pinus pollen supports an interpretation of a short-lived interval (<1000 years) of extremely warm, wet, forested conditions at this site.

Application of SWAT in Hydrological Simulation of Complex Mountainous River Basin (Part II: Climate Change Impact Assessment)

This study aims at analysing the impact of climate change (CC) on the river hydrology of a complex mountainous river basin—the Budhigandaki River Basin (BRB)—using the Soil and Water Assessment Tool (SWAT) hydrological model that was calibrated and validated in Part I of this research. A relatively new approach of selecting global climate models (GCMs) for each of the two selected RCPs, 4.5 (stabilization scenario) and 8.5 (high emission scenario), representing four extreme cases (warm-wet, cold-wet, warm-dry, and cold-dry conditions), was applied. Future climate data was bias corrected using a quantile mapping method. The bias-corrected GCM data were forced into the SWAT model one at a time to simulate the future flows of BRB for three 30-year time windows: Immediate Future (2021–2050), Mid Future (2046–2075), and Far Future (2070–2099). The projected flows were compared with the corresponding monthly, seasonal, annual, and fractional differences of extreme flows of the simulated baseline period (1983–2012). The results showed that future long-term average annual flows are expected to increase in all climatic conditions for both RCPs compared to the baseline. The range of predicted changes in future monthly, seasonal, and annual flows shows high uncertainty. The comparative frequency analysis of the annual one-day-maximum and -minimum flows shows increased high flows and decreased low flows in the future. These results imply the necessity for design modifications in hydraulic structures as well as the preference of storage over run-of-river water resources development projects in the study basin from the perspective of climate resilience.

Community Use of Face Masks against the Spread of COVID-19.

The role of face masks to prevent and control COVID-19 is critical, especially since asymptomatic or pre-symptomatic infected individuals can shed high loads of SARS-CoV-2 in the surrounding environment. In addition to being a two-way barrier to protect against virions droplets both in terms of “source control” (for the benefits of the community) and “physical protection” (for wearer), face masks also allow maintaining physiological temperatures and humidity of the nasal cavity and mouth, independently from the external environmental conditions. Beyond compromising the viral transmission speed, exposure to cold environments could have a detrimental effect on the host’s susceptibility to SARS-CoV-2. The innate human immune system becomes in fact weaker with cooler nose temperatures and thus more vulnerable to viral replication. Furthermore, there is evidence that warm, humid climates are associated with reduced spread of SARS-CoV-2, while cold dry conditions favor its stability and transmissibility. In the early stage of a viral infection, a physiological body temperature in the upper airways supports the innate immune system, endorsing the muco-ciliary clearance, inhibiting, or deactivating any first settlement of viruses. Face masks are therefore strongly recommended also outdoors, especially under cold weather conditions, not only as a physical barrier against the transmission of SARS-CoV-2, but also to prevent the rapid cooling of the nasal mucosa and the inhibition of the human innate defense of the upper airways.

Clast rind-paleosol record of the Antarctic early Alpine glaciation

The early Alpine glaciation is known from few sources detailing initial growth of ice either during the late Oligocene or early Miocene, localities limited to high summits of East Antarctica. The Ant-831 paleosol, developed in moraine emplaced during the Alpine event, has been studied with respect to its pedogenesis and to rinds recovered from its pebble pavement. This pedostratigraphic section is assigned a late Oligocene/early Miocene age on the basis of its fossil Coleoptera fauna and tundra vegetation, Fe/Al relative-age-dating parameters, and extensive pebble clast weathering. SEM, XRD and XRF analyses of rind specimens from the pebble pavement yield new information on the weathering history of the Beacon sandstone and its link to a juxtaposed paleosol. The paleosol provides a mirror image to weathering zones in pavement clasts, the salt-rich zones interpreted to have formed during the cold-dry paleoclimate of the post-Middle Miocene Climatic Optimum (MMCO ~15 Ma) following a stronger oxidizing paleoclimate of the earlier cold-wet phase of the Alpine glaciation. Essentially this database provides a 30-Myr window into the weathering progression from inception of the Alpine glaciation, through the warmer MMCO dated to ~15 Ma, to the onset of cold-dry conditions that brought on the later development of the Inland Ice Sheet.

Development of seasonal climate outlooks for agriculture in Finland

Abstract. Seasonal climate forecast products offer useful information for farmers supporting them in planning and making decisions in their management practices, such as crop choice, planting and harvesting time, and water management. Driven by the need of stakeholders for tailored seasonal forecast products, our goal was to assess the applicability of seasonal forecast outputs in agriculture and to develop and pilot with stakeholders a set of seasonal climate outlooks for this sector in Finland. Finnish end users were involved in both the design and testing of the outlooks during the first pilot season of 2019. The seasonal climate outlooks were developed using the SEAS5 seasonal forecast system provided by ECMWF. To improve the prediction skill of the seasonal forecast data, several bias adjustment approaches were evaluated. The tested methods increased the quality of temperature forecast, but no suitable approach was found for eliminating the biases from precipitation data. Besides the widely applied indices, such as mean temperature, growing degree days, cold spell duration, total precipitation and dry conditions, new sector-oriented indices (such as progress of growing season) have been implemented and issued for various lead times (up to 3 months). The first result of forecast evaluation, the development of seasonal forecast indices and the first pilot season of May–October 2019 are presented. We found that the temperature-based outlooks performed well, with better performance skills for short lead times, providing useful information for the farmers in activity management. Precipitation indices had poor skills for each forecasted month, and further research is needed for improving the quality of forecast for Finland. The farmers who have tested the seasonal climate outlooks considered those beneficial and valuable, helping them in planning their activities. Following the first pilot season, further research and implementation work took place to improve our understanding of the skill of seasonal forecasts and increase the quality of tailored seasonal climate services.

Cascading response of flora and terrestrial mollusks to last deglacial warming

The cascading impacts of climate-driven vegetation change on terrestrial invertebrates via trophic and habitat routes is a matter of outstanding concern. However, the combined responses of plant-animal associations in terrestrial ecosystems have seldom been reported on geological timescales, which raises the important questions of how frequently and to what extent such multi-trophic shifts in taxa have occurred during previous warming scenarios. Here we use a combination of mollusk, palynological, and climatic proxy evidence preserved within loess deposits in the southern Chinese Loess Plateau (CLP) to demonstrate how long-term changes in hydroclimatic dynamics during the past 26 kyr were reflected in the subsequent ecological changes. Specifically, there was a shift from a predominantly cold-tolerant mollusk fauna in a dry-steppe environment under cold-dry conditions during the last glacial, to a predominantly thermal-mesophilous fauna in a meadow-steppe environment under a warm temperate climate in the early-middle Holocene. Warmth-adapted mollusk species such as Opeas striatissimum and Punctum orphana were found to have been associated with several deciduous tree taxa (e.g., Corylus, Quercus, and Pterocarya) in both the Holocene record and in the modern ecosystem (based on surveys of 356 surface-soil plots). This suggests there is a clear ecological interdependency between specific vegetation types and mollusk assemblages. As such, the long-term vegetation-mollusk fossil records highlight the indirect impacts of climate change on terrestrial invertebrate turnover via plant-derived food structure and habitat routes, with major implications for understanding how these ecosystems are likely to respond to future climate changes.

Landscape evolution, post-LGM surface denudation and soil weathering processes from Dickinson Park mire, Wind River Range, Wyoming (USA)

At mid-latitudes, the transition from the Pleistocene to the Holocene was characterised by distinct and partially abrupt climatic changes. Also during the Holocene, climatic perturbations, with sometimes cold-dry conditions, have occurred. How land surfaces and soil development processes in high-mountains respond to these climatic oscillations is so far only poorly known. We traced the responses of surfaces in the alpine settings of the Wind River Range (Wyoming, US) by using a large mire as natural archive. This enabled us to reconstruct environmental conditions and ecosystem changes during the Holocene in this montane area. Although adjacent moraine deposits display 10Be exposure ages from the Last Glacial Maximum up to MIS16 or even older, the accessible sediment deposits covered only the Holocene (via radiocarbon dating). By applying a geoforensic approach and deriving sedimentation rates, major climatic signals were detected. A higher deposition (and consequently erosion) rate and thus a higher rate of geomorphic activity was measured for the known cold periods 9.4–10.2 ka BP, 4.2 ka BP and 2.5 ka BP. During the LIA, especially rapid aggradation of organic matter organic matter took place here. Rates of chemical weathering and soil formation seem to have been relatively low until about 5–6 ka BP but have since increased during the Late Holocene. This would fit previous observations of increasing moisture conditions after the mid-Holocene aridity period. In contrast to several other studies, no clear signs of major disturbances (erosion, weathering) during the 8.2 ka event could be observed. Together with the low levels of chemical weathering found here, we do not see any evidence that the climate was more humid during this period. Compared to previous findings, more humid conditions seemed to have returned earlier, i.e. about 5 kyr BP. In general, this landscape displayed a patchy pattern of reaction to environmental changes, as all events were not recorded in each mire profile.

Seed desiccation-tolerance is a common feature of threatened taxa in metalliferous tropical grasslands from southeastern DR Congo

In Katanga (southeastern Democratic Republic of Congo), the flora of copper and cobalt deposits is highly threatened by mining. Until mining activity ceases and restoration can take place, seed banking is one of the strategies to be considered for the conservation of these metallophytes of which 32 are strict endemics. In the tropics, however, many species have recalcitrant (desiccation-sensitive) seeds, making them unsuitable for long-term conservation. This study aimed at characterising the seed storage behaviour of 14 taxa of concern from metalliferous tropical grasslands in order to determine their storability in ex situ seed banks. Germination tests of 38 populations from 9 different sites were undertaken on fresh seeds and after 6, 12, 24 and 96 months in dry-cold conditions. The vast majority (93 %) of the sampled species exhibited high seed viability (>75 %). For each taxon studied, there was no significant decline in seed viability during storage. In general, seeds germinated faster after 8 years of storage. This study provides evidence that seed desiccation-tolerance is common among the metallicolous species of Katanga. This highlights their ability to be stored under dry-cold conditions, which opens the way for ex situ conservation programs in seed banks.

Distribution and abundance of zoeae I (Crustacea, Brachyura) on a coral reef in the southwest Gulf of Mexico

In this study we analyze both seasonal and inter-annual variations in the community parameters of Brachyura zoea I in the Parque Nacional Sistema Arrecifal Veracruzano. Planktonic samples from four transects were collected during three weather conditions: cold fronts; rainy and dry conditions in 2011 and 2012; and cold fronts and dry conditions in 2013. We measured temperature, salinity, and dissolved oxygen, in situ, to determine whether these parameters could explain the observed variations in the community patterns of brachyuran zoea I. We collected zoeae I of 18 species of brachyurans. The dominant species were Libinia dubia H. Milne Edwards, 1834; Menippe nodifrons Stimpson, 1859; and Callinectes sapidus Rathbun, 1896. The temperature and dissolved oxygen were the highest during the rainy conditions and the salinity during the dry conditions in the southern transects. The highest species richness (14) and diversity (2.97 bits individual-1) were found in central transects during cold front conditions. However, we found the highest species richness and diversity during the dry conditions, in the southern transects. Libinia dubia presented the highest density during cold fronts with 1592 ± 127 zoeae 100 m−3 in the northern transect, followed by C. sapidus in the north-central transect, this was observed for both species in the offshore zone. In conclusion, the parameters of the community of zoea I were influenced by the physical parameters measured in each sampling zone.

Quaternary sediment characteristics and paleoclimate implications of deposits in the Three Gorges and Yichang areas of the Yangtze River

The Three Gorges and Yichang areas of the Yangtze River are close to the eastern edge of the Qinghai-Tibet Plateau. Sediment proxies of paleoclimate trends in these areas are of great significance for the interpretation of the regional climatic impact of the episodic uplift of the Qinghai-Tibet Plateau. We examined the macro-sedimentary characteristics, clay mineralogy and geochemistry of sediments from the fan delta and lake deposits and the two river terraces of early and middle Quaternary age in the Yichang area and from the planation surfaces and the five main river terraces of early to late Quaternary age in the Three Gorges areas. The early and middle Quaternary had a generally warm-wet paleoclimate from 1260 to 300 ka. The regional climate changed to generally dry-cold conditions during late Quaternary (110–10 ka), that can be correlated to glacial cycles in the Tibetan Plateau. During the late Quaternary, especially after its Gonghe Movement (150 ka) uplift, the Qinghai-Tibet Plateau had a significant impact on regional climate. Comparing the formation age and source direction of the Wushan loess in the Three Gorge with loess in the western Sichuan (the Ganzi loess), in the Loess Plateau and distributing in the middle and lower reaches of the Yangtze River (the Xiashu loess), it can be found that coupling of the Kun-Huang Movement of the Qinghai-Tibet Plateau occurred at 1100–600 ka and Mid-Pleistocene Transition and global cooling resulted in the sharp increase of East Asian winter monsoon and plateau monsoon, forming the western Sichuan loess and Xiashu loess. The Gonghe movement (150 ka) of the Plateau once again enhanced the plateau monsoon and blocked the Indian summer monsoon moving north-eastward. As a result, the cold-dry climate appeared in the Sichuan Basin and the Three Gorges area, resulting in the deposition of loess from the Zoige Basin to Wushan area.

Resonance of the ‘4.2ka event’ and terminations of global civilizations during the Holocene, in the palaeoclimate records around PT Tso Lake, Eastern Himalaya

Climate driven changes have impacted various civilizations and have major influence on human population globally. Remote regions such as the Himalaya also archived these climatic events in various proxies. The Eastern Himalaya region has recorded the Holocene climate change events in numerous proxy records. A multi–proxy record of the early to late–mid Holocene climate change from the catchment of PankangTeng Tso (PT Tso) Lake at an altitude of 3935 m asl in the Tawang district of Arunachal Pradesh was studied. A 90 cm sediment profile showed a synchronous pattern of Holocene climate changes in the palynological, environmental magnetic and carbon isotope data recorded. Dominant cold-humid conditions at 4625 cal yr BP followed by a cold-dry period was documented in the proxy data. The vegetation vis–à–vis climate varied throughout the Holocene and cold–dry conditions along with sub-alpine vegetation prevailed in the region around the “4.2ka event”. Human activities and environmental changes in the Tawang district during the Holocene probably impacted the vegetation during this significant period of the development and demise of major global civilizations.

Wheat performance with subclover living mulch in different agro-environmental conditions depends on crop management

Abstract Intercropping has been proposed as a useful strategy for reducing external inputs in cereal-based cropping systems, while maintaining adequate crop yield. Intercropping of wheat and subclover, implemented as living mulch, is recommended, but there is limited experimental proof for its suitability in different environments. The main objective of this study was to provide an overview and evaluation of wheat-subclover intercropping under different agro-environmental conditions. Coordinated field experiments were conducted over a two-year period in six sites located in four agro-environmental zones [Atlantic North (Neu-Eichenberg, Germany), Continental (Freising, Germany – Tanikon, Switzerland), Mediterranean North (Viterbo, Italy), Mediterranean South (Sidi Alla Tazi and Sidi El Aidi, Morocco)]. Wheat–subclover intercropping was compared with a pure wheat. Additionally, other treatments adopted in specific sites were: soil tillage (conventional and minimum tillage); fertilization input (high and low level); cropping system (conventional and organic). The measurements recorded were: soil coverage, wheat and subclover phenological stages, wheat grain yield and yield components, subclover and weed biomass. The data of each site were analyzed separately and were also used for a meta-analysis to obtain an overview of how pedo-climatic conditions affect the interactions of subclover living mulch with wheat and weeds. Subclover biomass was the highest at Viterbo (228 g m−2 of DM) proving its adaptability to the climatic conditions of Mediterranean North characterized by mild temperature and abundant rainfall. Wheat-subclover intercropping reduced weed infestation (from 22 to 75% in Mediterranean South and North, respectively). Intercropping also resulted in grain yield losses compared to pure wheat in Mediterranean North and Continental (on average −16 and −14%, respectively), probably because of the competition between the intercropped species. In the agro-environmental zones where subclover growth was limited by cold temperatures (Atlantic North) or dry conditions (Mediterranean South), hardly any grain yield reduction of intercropped wheat was observed. Subclover biomass and wheat grain yield were also negatively correlated and yield reductions were generally due to a reduced number of fertile spikes. The yield gap between intercropped and pure wheat was reduced when: (i) there was a proper spatial arrangement of subclover and wheat; (ii) the amount of added mineral nitrogen fertilizer was reduced, while compost application did not influence the cropping systems. The use of subclover living mulch in wheat appears to be most suitable for low input systems. Future research should focus on the development of appropriate crop management practices for intercropping in order to avoid wheat yield loss.

Nasal variation in relation to high-altitude adaptations among Tibetans and Andeans.

High-altitude (>2500 m) populations face several pressures, including hypoxia and cold-dry air, resulting in greater respiratory demand to obtain more oxygen and condition inspired air. While cardiovascular and pulmonary adaptations to high-altitude hypoxia have been extensively studied, adaptations of upper-respiratory structures, e.g., nasal cavity, remain untested. This study investigates whether nasal morphology presents adaptations to hypoxic (larger noses) and/or cold-dry (tall/narrow noses) conditions among high-altitude samples. CT scans of two high- and four low-altitude samples from diverse climates were collected (n = 130): high-altitude Tibetans and Peruvians; low-altitude Peruvians, Southern Chinese (temperate), Mongolian-Buriats (cold-dry), and Southeast Asians (hot-wet). Facial and nasal distances were calculated from 3D landmarks placed on digitally-modeled crania. Temperature, precipitation, and barometric pressure data were also obtained. Principal components analysis and analyses of variance primarily indicate size-related differences among the cold-dry (Mongolian-Buriats) and hot-wet (Southeast Asians) adapted groups. Two-block partial least squares (PLS) analysis show weak relationships between size-standardized nasal dimensions and environmental variables. However, among PLS1 (85.90% of covariance), Tibetans display relatively larger nasal cavities related to lower temperatures and barometric pressure; regression analyses also indicate high-altitude Tibetans possess relatively larger internal nasal breadths and heights for their facial size. Overall, nasal differences relate to climate among the cold-dry and hot-wet groups. Specific nasal adaptations were not identified among either Peruvian group, perhaps due to their relatively recent migration history and population structure. However, high-altitude Tibetans seem to exhibit a compromise in nasal morphology, serving in increased oxygen uptake, and air-conditioning processes.

Hendra Virus Spillover is a Bimodal System Driven by Climatic Factors.

Understanding environmental factors driving spatiotemporal patterns of disease can improve risk mitigation strategies. Hendra virus (HeV), discovered in Australia in 1994, spills over from bats (Pteropus sp.) to horses and thence to humans. Below latitude -22°, almost all spillover events to horses occur during winter, and above this latitude spillover is aseasonal. We generated a statistical model of environmental drivers of HeV spillover per month. The model reproduced the spatiotemporal pattern of spillover risk between 1994 and 2015. The model was generated with an ensemble of methods for presence-absence data (boosted regression trees, random forests and logistic regression). Presences were the locations of horse cases, and absences per spatial unit (2.7×2.7km pixels without spillover) were sampled with the horse census of Queensland and New South Wales. The most influential factors indicate that spillover is associated with both cold-dry and wet conditions. Bimodal responses to several variables suggest spillover involves two systems: one above and one below a latitudinal area close to -22°. Northern spillovers are associated with cold-dry and wet conditions, and southern with cold-dry conditions. Biologically, these patterns could be driven by immune or behavioural changes in response to food shortage in bats and horse husbandry. Future research should look for differences in these traits between seasons in the two latitudinal regions. Based on the predicted risk patterns by latitude, we recommend enhanced preventive management for horses from March to November below latitude 22° south.