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Understanding how climate change-induced alterations in rainfall patterns impact the composition and structure of plant diversity is crucial. Examining variations in plant life forms is vital for comprehending ecosystem dynamics. This study analyzes plant life form diversity, rainfall variability, and the impact of different rainfall patterns on plant diversity over 15 years in the Gurbantünggüt Desert, a temperate desert in Central Asia. The study identified 96 plant species in the area, comprising 27 winter annuals and 33 perennial herbs. Over the past 15 years, species diversity has remained stable, while diversity among plant life forms has varied significantly. Winter annuals consistently dominated, showing a significant linear increase in importance values (slope=1.135). Conversely, perennial shrubs like Haloxylon ammodendron and Haloxylon persicum exhibited a marked declining trend. Over the past 15 years, the occurrence of minor (

Questions: Annual species have evolved sets of germination cues that are thought to be predictive of the post‐germination environment. In naturally patchy environments, germination microsites often vary considerably in the amount of light they receive and in the diurnal temperature fluctuations they experience. However, whether species' differential germination responses to light and temperature are associated with their spatial patterns of occurrence remains largely untested. Location: Mediterranean‐climate woodlands in Southwest Western Australia. Methods: We surveyed species' occurrences in annual plant communities in 150 quadrats across gradients of canopy cover and litter cover. Nineteen species recorded in this survey were then included in a germination experiment that manipulated (1) Light vs Dark (12 h light or continuous dark) approximating seeds near the soil surface vs those covered by litter and (2) Cold vs Warm temperature regimes (7/18°C and 7/24°C) approximating diurnal fluctuations experienced in shaded vs sun‐exposed microsites, respectively. Results: In the germination experiment, six species had highest germination probabilities in the Light treatment (regardless of temperature), five in Cold + Light, one in Warm + Light, two were indifferent to the treatments, and four did not germinate at all. Binomial linear mixed‐effects models showed that species' maximum responses to light and temperature did not explain their spatial distributions along canopy cover and litter cover gradients, contrary to theoretical expectations of germination being a strong driver of species' occurrences. Conclusions: Despite variation in species' responses to experimental treatments, no association was found with their field microsite associations. Germination strategies in our system were wider than expected for Mediterranean systems. Our results support that germination cues are not strong drivers of microhabitat associations in this system. [ABSTRACT FROM AUTHOR]

Premise: The lateral membranous expansions of fruits, commonly referred to as wings, have long been theorized to serve only dispersal functions. Alternatively, because winged fruits typically have earlier seed germination than unwinged fruits, we hypothesized that wings could increase the contact surface with water, ultimately triggering earlier germination. Methods: We investigated this alternative hypothesis by exploring the potential role of fruit wings on germination in the heterocarpic species Anacyclus clavatus (Desf.) Pers. (Asteraceae), which produces both winged and unwinged fruits. First, we measured the speed and degree of water absorption in winged and unwinged fruits. Second, we investigated the effects of wings on germination performance, by either reducing wing size or by preventing water absorption by sealing wings with wax. Next, we tested the influence of water availability on the germination performance of winged and unwinged fruits by reducing the water potential. Results: Winged fruits absorbed more water at a faster rate than unwinged fruits. The sealing of wings delayed germination, whereas germination time was not significantly altered by wing cutting. The restriction of water availability by decreasing water potential significantly delayed seed germination of unwinged fruits, whereas winged fruits remained unaffected. Conclusions: Altogether, our results support the effect of wings on germination and cast doubt on the unique role of wings in dispersal. Whether or not wings contribute to dispersal, we propose that they also improve seed germination and seedling establishment by facilitating water absorption after the release from their mother plants. [ABSTRACT FROM AUTHOR]

This document is a compilation of various scientific articles and reports related to sustainable agriculture and soil health. It covers topics such as Continuous Living Cover (CLC) in agriculture, the impact of different agricultural practices on soil quality and water retention, the role of biodiversity in ecosystem functioning, and the relevance of indigenous traditional ecological knowledge. The articles emphasize the benefits of CLC systems, including improved soil and water quality, diversified agricultural landscapes, and economic and environmental goals. However, the adoption of CLC practices has been slow due to challenges such as climate limitations and lack of policy support. The document provides a comprehensive overview of current research and knowledge in the field of sustainable agriculture and soil health. [Extracted from the article]

Winter annual plants play an important role in arid and semiarid ecosystems because of their rapid response to resource pulses, which drive primary production that provides resources for herbivores and pollinators. Understanding the factors that control annual plant growth is key to predicting how arid and semiarid ecosystems will respond to changes in climate and resource availability from anthropogenic activities. We used a long-term nutrient enrichment experiment that spanned precipitation and urbanization gradients in central Arizona, USA, to examine the effects of climate, surface soil properties, soil nutrient availability and shrub cover on winter annual plant growth. At a landscape scale, aboveground net primary production (ANPP) of winter annual plants had a positive, nonlinear relationship to the amount of precipitation received from October through March of the current growing season. We found evidence for sequential resource limitation of ANPP initially from water then nitrogen and phosphorus. The resource limitation cascade was modified by surface soil properties and location relative to shrubs (under or between shrubs), highlighting the effect of small-scale factors on large-scale processes. Specifically, gravel cover had a negative effect on ANPP, and the effect of shrub cover on ANPP depended on nitrogen and current season rainfall. Our study emphasizes how small-scale factors, such as gravel cover, nutrient availability and presence of shrubs, can interact with large-scale drivers, such as seasonal precipitation, to affect interannual variation in winter annual plant production in the northern Sonoran Desert. Sonoran Desert landscape showing production of winter annuals 363 x 241mm (300 x 300 DPI) [ABSTRACT FROM AUTHOR]

To persist (without immigration) in habitats with unpredictable environmental conditions, annuals must produce seeds each year or have a seed bank. Thus, we predicted that compared to perennials, annuals have a wider germination temperature range (GTR, the difference in temperature between the week with the highest and the week with the lowest germination during the natural germination season). We determined the GTR via germination phenology data for 350 herbaceous species in 59 families from the eastern USA: summer annuals (SA), 63; winter annuals (WA), 83; monocarpic perennials (MP), 28; and polycarpic perennials (PP), 176. There was no significant phylogenetic signal for the GTR. The width of the GTR during the first spring germination season was 9.6, 8.7 and 8.8°C for MP, PP and SA, respectively, and during the first autumn germination season 12.8, 11.8 and 12.4°C for MP, PP and WA, respectively. Annuals did not have a wider GTR than perennials in either the spring or the autumn germination season. Our data suggest that selection for early germination in either spring or autumn has resulted in only small differences in the GTR. We predict that global warming will have little or no effect on reshaping the germination phenology of herbaceous species of temperate eastern North America. [ABSTRACT FROM AUTHOR]

Native and exotic species richness is expected to be negatively related at small spatial scales where individuals interact, and positive at larger spatial scales as a greater variety of habitats are sampled. However, a range of native- exotic richness relationships (NERRs) have been reported, including positive at small scales and negative at larger scales. We present a hierarchical metacommunity framework to explain how contrasting NERRs may emerge across scales and study systems, and then apply this framework to NERRs in an invaded winter annual plant system in southwest Western Australia. We analysed NERRs at increasing spatial scales from neighbourhoods (0.09 m2) to communities (225 m2) to metacommunities (greater than 10 ha) within a multilevel structural equation model. In contrast to many previous studies, native and exotic richness were positively related at the neighbourhood scale and were not significantly associated at larger scales. Heterogeneity in soil surface propertieswasweakly, but positively, associated with native and exotic richness at the community scale. Metacommunity exotic richness increased strongly with regional temperature and moisture availability, but relationships for native richness were negative and much weaker. Thus, we show that neutral NERRs can emerge at larger scales owing to differential climatic filtering of native and exotic species pools. [ABSTRACT FROM AUTHOR]

Climate can influence plant demographic processes and life stages in different ways, but such details are often ignored in analyses that focus on adult life stages and annual climate averages. In particular, the effects of climate on seeds may be hugely important under climate change. Climate is known to influence seed survival and germination, which in turn can strongly affect population persistence and community dynamics. We investigated climate and other environmental effects on seed viability and germination probabilities of six winter annual plant species persisting in small, isolated habitat fragments in the Mediterranean- climate region of southwestern Australia. Seeds were collected from southern (cool) and northern (warm) bushland remnants and factorially placed into each location to assess the effects of natural dormancy alleviation via after- ripening. Seeds were then exposed to cool and warm germination treatments (representing average germination conditions in the two remnants). For five of the six species, seeds from warm maternal populations had higher germination probabilities (or germinated more seeds sooner). Regardless of maternal population, germination probabilities were higher (or germination was more rapid) for seeds that were after- ripened in the warm remnant for almost all species. For all species, germination was higher (or more rapid) under the warmer germination temperatures. We also found strong microsite effects on seed viability for some species. In the absence of adaptation in dormancy regulation and germination physiology, our results indicate that most of the winter annual species studied will germinate higher fractions of seeds under future climate conditions due to the cumulative effects of warmer maternal, after- ripening, and germination environments. The fate of isolated populations under climate change may therefore depend strongly on postgermination survival and reproduction to prevent seed bank depletion. [ABSTRACT FROM AUTHOR]

Community reassembly is an important concept in community ecology, but in most circumstances cannot be observed and is hypothetical. Reassembly of communities is an observable process that can be examined effectively following species invasions. Our study system in southeastern Arizona has declined in diversity and abundance of native winter annual plants coincident with a sustained irruption of a nonnative invasive Eurasian species, Erodium cicutarium, and a major reassembly of the winter annual plant community. To understand the role of E. cicutarium in the reassembly process, we initiated a multiyear E. cicutarium removal experiment that varied the timing of removal. Species richness was higher as a result of removal, although this effect was variable over time. Surprisingly, the abundance of native species collectively was decreased by E. cicutarium removal. However, previously rare Astragalus nuttallianus appears to be facilitated by E. cicutarium, as demonstrated by higher density and relative abundance in the presence of E. cicutarium, and is now codominant. Excluding A. nuttallianus abundance, the remaining native species are collectively increased by removal of E. cicutarium. Although our results showed strong effects of removal, the timing of removal never significantly affected any plant variables. Our experiment implicates a major role for E. cicutarium in the reassembly of the native plant community. Our work suggests a broadening of perspective on processes structuring annual plant communities in arid regions, and calls for an integrated approach beyond the recent popular focus on the interaction between competition and the physical environment. [ABSTRACT FROM AUTHOR]

Abstract: Field studies were conducted at three Missouri locations in 2004 and 2005 to evaluate the effects of fall and early spring herbicide applications on soil temperature, soil moisture content, and insect populations in no-till soybean production systems. All three experiments received herbicide applications in the fall, 60 days prior to planting, 30 days prior to planting, and seven days prior to planting. During a period from April 1 to May 31, chlorimuron plus sulfentrazone plus 2,4-D applied 60 days prior to planting did increase soil temperatures at a 2.5cm depth compared to the untreated when soil temperatures were above 20°C. However, differences in soil temperature were inconsistent when temperatures fell below 20°C. Significant treatment differences in the percent volumetric soil moisture content were present at two weeks before (WBP) and two weeks after planting (WAP). Two WBP, soil moisture in the untreated averaged 46.0% volumetric soil moisture content, while the herbicide treated plots ranged from 48.8% to 50.8%. Two WAP, the untreated averaged approximately 5.0% less soil moisture than any of the herbicide treatments. Shake-cloth samples taken at five and seven WAP revealed significantly higher numbers of total insects per 0.8m2 in the untreated compared to the herbicide treated plots. At five WAP the untreated averaged 12.5 total insects per 0.8m2, while the herbicide treated plots ranged from 0.8 to 1.5 total insects per 0.8m2. Seven WAP the untreated averaged almost 19 total insects per 0.8m2 while the herbicide treated plots averaged only 2.1 to three total insects per 0.8m2. [Copyright &y& Elsevier]

Long-term studies of seasonal changes in temperature and light : dark requirements for germination were conducted on seeds of Plantago virginica (87 months), Silene antirrhina (32.5 months) and Triodanis perfoliata (36.5 months), buried under natural temperature regimes in central Kentucky, USA. Seeds of P. virginica exhibited an annual conditional dormancy/non-dormancy cycle; thus, the species has the potential to behave as a facultative winter annual. Seeds of T. perfoliata and S. antirrhina had an annual dormancy/non-dormancy cycle, but dormancy induction was not completed until April or May. Thus, depending on the year, 3–21% and 1–97% of the S. antirrhina and T. perfoliata seeds, respectively, germinated in March and these species also have the potential to behave as facultative winter annuals. Data from long-term buried seeds studies in central Kentucky are now available for 16 native (including the three species reported in this paper) and nine non-native winter annuals of eastern North America. Buried seeds of non-natives, as well as those of natives whose geographic range extends beyond eastern North America, tend to have a conditional dormancy/non-dormancy cycle, while those of natives with a range restricted to eastern North America tend to have a dormancy/non-dormancy cycle. However, testing of this hypothesis will have to await data for more winter annuals so that a phylogenetically independent analysis can be conducted. [ABSTRACT FROM AUTHOR]

Many studies have investigated the density-dependent regulation ofannual-plant populations on coastal sand dunes, but few have explored theconsequences of competition for the coexistence of plants in these simplecommunities. We used neighbourhood techniques to parameterize competition anddispersal functions from field data collected for two species of dune annual( Aira praecox and Erodium cicutarium)over three successive years, and then combined these functions into spatiallyexplicit simulation models. The population size of Airavaried enormously between years, while Erodium remainedsteady. Competition with neighbours reduced the spike length of Aira plants only in one of the three years (when itspopulation density was highest), while competition with neighbouring Erodium plants appeared to result in the local death of Aira plants. However, these density-dependent effects werefar too weak to generate the observed changes in the population size of Aira among years, or to maintain populations below theupper limits observed. The large-seeded Erodium wasaffected by intraspecific competition but was unaffected by small-seeded Aira plants. Therefore, the larger-seeded species wascompetitively superior to the smaller-seeded species, an affect that couldpromote coexistence (albeit weakly) by a competition-colonisation trade-off.Modal dispersion distances of Aira and Erodium were 45 and 60 mm respectively,greater than the radius within which competitive interactions occurred (40mm). Theoretical studies suggest that under these conditions thespatial arrangement of plants should be nearly random. In fact Aira was spatially aggregated, especially when rare,suggesting that patchy mortality across the dunes was important in generatingspatial structure. The study suggests that density dependence only weaklyregulates dune annual communities, while year-to-year environmental variationexert major influences on population sizes and spatial structures. [ABSTRACT FROM AUTHOR]

Cattle producers typically feed hay and supplement for a 90- to 120-d window to maintain cows during the winter in Alabama. Relying on stored feeds can increase management system costs and labor needs. The objective of this demonstration project was to compare alternative, reduced labor management systems commonly used by producers in the region for diet quality and animal performance responses. A 75-day trial evaluated the use of three systems (n = 3 replications per system): 1) rotationally grazed-winter annuals (GWA) on a 14-day rotation, 2) free-choice whole cottonseed (WCS) and bermudagrass hay, or 3) 50% soybean hulls and 50% corn gluten feed (SH:CGF) fed on alternate days at up to 1% BW daily and free-choice bermudagrass hay. GWA had the greatest diet digestibility (P < 0.0001), and SH:CGF and WCS were not different from one another (88.7%, 64.3%, and 64.6%, respectively). Diet CP values differed (P < 0.0001) for WGA (21.5%), SH:CGF (13.1%), and WCS (11.2%), respectively. Initial and final cow BCS was not different among treatments (P = 0.1558). Cow ADG was greater (P = 0.0370) on GWA than SH:CGF and WCS (0.9, 0.2, and 0.2 kg, respectively), and calf ADG followed a similar pattern (1.5, 1.2, and 1.1 kg/day for GWA, WCS, and SH:CGF, respectively). This project demonstrates that winter annuals provided 75 days of high-quality winter grazing and resulted in greater animal performance than the other diets. However, all diets provided reduced labor options to maintain cows throughout the winter. [ABSTRACT FROM AUTHOR]