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Wool production in arid and semiarid rangelands is strongly affected by environmental variability. Seasonal fluctuations of the environmental conditions drive variations in the nutritional status of the sheep, wool growth and quality. The variation of fibre diameter during the annual growth period can be observed through the Fibre Diameter Profiles (FDP). The FDP provide a retrospective description of animal responses to varying environmental and management conditions during the wool growth period. Certain characteristics of FDP influence wool quality because this is associated with the performance during processing. The aim of this paper was to assess the variation of the FDP during the 2014–2015 wool growth period on farms located in a longitudinal environmental gradient of Northern Patagonia, Argentina. Some features of the FDPs were found to be associated to the geographical location of the farms. For example, the minimal fibre diameter occurred at different times on the farms during the annual wool growth. The results of this paper support the relevance of the environment in generating seasonal variations in fibre diameter, which might be associated to animal stressful circumstances. However, future research is needed to better understand the influence of climatic conditions and other stressful circumstances for animals. • The biophysical conditions produced variability in fibre diameter profiles. • The farms located at the longitudinal extremes recorded the greatest variability. • The minimum and maximum fibre diameters occurred at different times among farms. [ABSTRACT FROM AUTHOR]

Native desert plants have structural adaptations that maximize photosynthesis rates and minimize water loss. They can be successfully utilized as soil cover crops in drip-irrigated vineyards where water availability is low. The objective of this paper is to study seed germination conditions and to recommend which best species is most apt as soil cover crop in drip-irrigated vineyards. Seed weight (the higher the seed weight, the greater the success of mechanical seeding) and germination tests (at 15, 20, 25, 30, and 35 °C in light and dark conditions) were carried out for six species native to Mendoza, Argentina. Germination percentage (GP) and mean time germination (MTG) were calculated. Digitaria californica (C 4 ) had the highest GP (97% in light condition), which is recommended as a cover crop because of its seed germination potential. Pappophorum phillippianum (C 4 ) had a 70% GP in light conditions (regardless of temperature) and a high seed weight. Leptochloa dubia (C 4 ) and Sporobolus cryptandrus (C 4 ) reached the highest GP at the highest temperature, although S. cryptandrus had the lowest seed weight. Nassella tenuis (C 3 ) averaged 54% GP at 25 °C in light conditions. The GP of Setaria leucopila (C 4 ) was not affected by temperature (26% in light, and 16% in darkness). Based on the GP results, S. leucopila was the worst choice of the six species. Hence, during seeding, soil temperature should be high (>20 °C) to ensure a rapid plant establishment of all species. [ABSTRACT FROM AUTHOR]

Abstract: In recent years, there has been an increasing interest in the study of climate change effects on plant phenology. However, the effects of other more localized components of global change such as land degradation have been almost completely ignored. In this paper we evaluate the phenological patterns of 10 plant species at three sites with contrasting levels of land degradation due to overgrazing in the Patagonian Monte, Argentina, and their relationship with plant morphology, browsing intensity, and plant competition. Plant phenology differed among sites in eight species, but plant responses were species-specific. In six species the dormancy and senescence periods were shorter indicating longer growing cycles at high degradation than at low degradation site. Generally, plants growing at high degradation site present longer and frequently incomplete vegetative periods and shorter and less dominant reproductive periods than those at low degradation site. However, in some species the duration of reproductive periods was greater in the high degradation site. Plant size (i.e. height, area, and/or internal cover) affected plant phenology in seven species. In contrast, browsing and neighbor''s cover were rarely related to plant phenology. Our results suggest that other global change components such as land degradation may affect plant phenology. [Copyright &y& Elsevier]

Abstract: Cacti are a plant group of special conservation interest because of their economic value and the threats they face. In this paper, we studied cactus diversity in the Saltenian Calchaquíes Valleys, the most diverse region in Argentina. Our goals were: 1) to analyze diversity patterns, 2) to evaluate the effectiveness of the extant reserve network, 3) to select the complementary areas for cactus conservation, and 4) to evaluate the effectiveness of endemic cactus diversity as surrogate for all cactus diversity in this region. In our study, we recorded 41 cactus species, 22 of which were endemic. The most diverse cells of the survey grid were located in the High Monte ecoregion and in transition zones between this ecoregion and the Dry Chaco and Central Andean Puna ecoregions. Spatial congruence between species richness and endemism was high. The extant Saltenian Calchaquíes Valleys reserve network was effective for the cactus conservation because only three cells were necessary to maximize their protection with minimum representation. Endemic species had a good performance as surrogates of all cactus diversity. The present study is the first to define cactus diversity and to establish conservation strategies in this singular region. [Copyright &y& Elsevier]

Abstract: Grazing by domestic exotic herbivores on native vegetation in Patagonian steppes has led to the deterioration of forage resources, where grasses are replaced by shrubs, and preferred grasses by non-preferred ones. Therefore, attempts at breeding and regeneration should start by identifying species with potential forage capability. Two perennial high-preferred species are the focus of this paper: Hordeum comosum and Koeleria vurilochensis. For the first time, we studied their morphological traits, dormancy level, and their temperature and water germination requirements, through thermal- and hydrotime models. H. comosum seeds were solid, large and heavy, while K. vurilochensis seeds were soft, small and light. Neither light-quality nor alternating temperature affected the dormancy level in seeds of both species. Seeds of H. comosum and K. vurilochensis required, respectively, 768.74 °Ch and 2217.89 °Ch to germinate; alternatively, base temperature was higher for H. comosum than for K. vurilochensis. The hydrotime required by H. comosum was 26 MPah and 110 Mpah for K. vurilochensis but, base water potential was −0.99 MPa and −1.45 MPa, respectively. For all the conditions, H. comosum displayed a higher germination rate compared to K. vurilochensis seeds. Deeper knowledge on the morphological and germination traits of seeds is a key step toward breeding and restoration of forage potential species. [Copyright &y& Elsevier]

Abstract: In arid and semiarid regions of Central West Argentina, paleoenvironmental conditions and history of the Holocene vegetation is still scanty. This paper presents the analysis of palynological records of two Mid- to Late Holocene alluvial sequences (La Escala -LES- and Brazo Abandonado -BA-) in the fluvial basin of the Arroyo La Estacada (33°27′S and 69°03′W), placed in the Cordillera Frontal central piedmont of Mendoza province. Variations in pollen assemblages of the two sequences related to the environments developed in the floodplains of the arroyo allowed us to infer the evolution of local plant communities. Between the ca. 4000 and 3000 14C years BP and between ca. 500 and 400 14C years BP, a larger representation of hydrophytic communities related to environments with local water availability was inferred; and between ca. 3000 and 500 14C years BP an increase in shrubby xerophytic communities related to environments with lower water availability was detected. These results led us to propose that the Holocene pollen spectra fluctuations observed in the alluvial sedimentary sequences prove mainly changes in plant communities of the floodplain environment in response to the fluvial dynamics of the arroyo. [Copyright &y& Elsevier]

Abstract: In grazed semiarid ecosystems, considerable spatial variability in soil infiltration exists as a result of vegetation and soil patchiness. Despite widespread recognition that important interactions and feedbacks occur between vegetation, runoff and erosion, currently there is only limited quantitative information on the control mechanisms that lead to differences in infiltration from different vegetation types. In this paper, we determine (i) the relationship between vegetation and soil surface characteristics and (ii) the soil infiltration rate by using rainfall simulations on runoff plots (0.60 × 1.67 m) in three plant communities of northeastern Patagonia: grass (GS), degraded grass with scattered shrubs (DGS), and degraded shrub steppes (DSS). Our results clearly indicate that vegetation and soil infiltration are closely coupled. Total infiltration was significantly higher in the GS (69.6 mm) compared with the DGS and DSS (42.9 and 28.5 mm, respectively). In the GS, soil infiltration rate declined more slowly than the others communities, reaching a terminal infiltration rate significantly greater (57.7 mm) than those of DGS and DSS (25.7 and 12.9 mm, respectively). The high rate of water losses via overland-flow may limit the possibilities for grass seedling emergence and establishment and favor the persistent dominance of shrubs. [Copyright &y& Elsevier]

Abstract: In extra-Andean Patagonia, wet meadows contrast with the prevailing arid steppes, and present a gradient of water availability from the periphery to the center. The objectives of this paper are to describe the spatial and temporal variation of aerial net primary production (ANPP) of Patagonian meadows, and to obtain a model for the relationship between the normalized difference vegetation index (NDVI) and ANPP. We determined ANPP in four regionally scattered meadows during 3–5 years and in three positions of the gradient of water availability. In one meadow, we correlated ANPP with NDVI during 2 years. Annual ANPP was 2–3 times larger in the center than in the periphery, and also varied 2–3 fold among the four meadows. The interannual variation of ANPP was high and similar across meadows and zones. ANPP was closely correlated with NDVI through a linear model. Within the growing season, the central zone had a more extended period of high NDVI into the summer than the peripheral and the intermediate zones. We conclude that (1) the local variation of ANPP across the gradient of water availability is strong and must be taken into account for management, and (2) the highly variable ANPP may be monitored by remote sensing. [Copyright &y& Elsevier]

Abstract: Annual growth rings are well-defined in some shrubby species distributed along the Patagonian steppe and provide useful information to identify the environmental factors that influence the radial growth of shrubs in the region. However, little is known about variations in ring width from these species and their relationships with local environment. In this paper we present 18 growth ring width chronologies covering the last 2–3 decades from the shrub Anarthrophyllum rigidum (Fabaceae) encompassing most of its natural range of distribution in Argentina. Interannual variations in growth were first analyzed collectively to identify common regional patterns. In addition, shrub growth at each site was compared with local climate records and site-specific characteristics. Based on a principal component analysis (PCA), sites were joined in four major groups related to the site proximity to the Andes (foothills versus Patagonian plateau) and latitude (north versus south Patagonia). The relatively similar percentage of PCA variance associated with each group reflects environmental differences among sites. Consistent with this observation, we noted large variability in the responses of the A. rigidum woody growth to regional climatic fluctuations. At most sites, this species is favored by abundant winter precipitation, warmer spring and autumn temperatures (controlling the duration of the growing season), cool summers, or a combination of these factors. However, deviations from these patterns are also recorded. Our study represents the first large-scale dendroclimatological analysis of a shrubby species in southern South America. The results presented here provide information on the main patterns and factors affecting the growth of A. rigidum in Patagonia, and may be useful for determining well-suited practices for management and conservation of this ubiquitous species. [Copyright &y& Elsevier]

Abstract: In arid and semiarid ecosystems, primary productivity and nutrient cycling are directly related to the amount and seasonal distribution of precipitation. However, depending on morphological, phenological, physiological, and biochemical traits, plants may influence the quality and quantity of organic matter inputs to the soil and thus the biomass and activity of the soil biota responsible for carbon and nitrogen dynamics. In this paper, we review the available knowledge on plant functional traits and their impacts on ecosystem processes such as N and C cycling throughout the Monte Phytogeographical Province. We address the mechanisms of N conservation, the quantity and quality of leaf litterfall and root traits of the dominant plant life forms and their effects on decomposition processes, soil organic matter accretion, and soil-N immobilization and mineralization. We conclude that plant functional traits affect ecosystem processes in the Monte Phytogeographical Province since the chemistry of senesced leaves and root biomass exerts an important control on organic matter decomposition and N availability in soil. [Copyright &y& Elsevier]

Abstract: This paper documents the main features of climate and climate variability across the Monte Desert for the Last Glacial Maximum, the Glacial–Interglacial transition, and the Holocene on the basis of proxy records and for the 20th century using instrumental observations. The climate in the Monte is determined by interactions between regional physiography and atmospheric circulation in the 25–45°S sectors of South America. Although arid and semi-arid conditions prevail across the Monte, its large latitudinal extent and complex topography introduce many particularities at local scales. Paleoclimatic records and model simulations of past climates suggest significant variations in the atmospheric circulation, temperature and rainfall patterns since the Last Glacial Maximum. High-resolution proxy records east of the Andes support the existence of complex climatic patterns with similar temperature changes across the whole region but opposite precipitation variations between subtropical and mid-latitude sectors in the Monte during the past millennium. The present-day climate is depicted in terms of the space and time variability of the near-surface temperature, rainfall and tropospheric wind patterns. Uneven temperature trends over the Monte were recorded for two separate (1920–44 and 1977–2001) global warming periods in the 20th century. Additional warming evidence in the region is provided by extreme temperature records. The non-homogeneous regional pattern of precipitation shows a positive long-term increase between 30 and 40°S during the interval 1985–2001. Ensemble of climate experiments accomplished with general circulation models provide the most likely changes in temperature and rainfall to occur by the end of this century in relation to present climate. Temperature increases, larger in summer than in winter, will be concurrent with more abundant precipitations in summer, but almost no changes or even small reductions in winter across the Monte. [Copyright &y& Elsevier]

Abstract: The current paper analyses various environmental parameters in relation to wheat yields in Bordenave, Province of Buenos Aires, Argentina. The variables used are: precipitation (ppt), maximum (Tx) and minimum temperature (Tmi) as well as those obtained by applying the Palmer model. Decadic and phenological scales are used for data corresponding to the period 1977–2000. The stepwise method is used to obtain a multi-variate equation to calculate yield taking into account environmental variables only. For a five variates model the coefficient of determination, equals 95.79% and the standard error of estimation is 129.0kgha−1. In the sample yields, the incidence of total variability for thermal variables is 42.7% and for hydrological variables, 53%. The value and sign of the correlation coefficients were analysed throughout the cultivation cycle. The coefficient is mainly responsible for yield variance during tillering and stem elongation. There is good correlation with the values of Palmer''s Drought Severity Index (PDSI) for the flowering and grain filling stages. [Copyright &y& Elsevier]