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Annual screenings of forage grasses and legumes for shade tolerance were conducted from 1996 to 2001 in the outdoor Shade Tolerance Screening Laboratory at the Horticulture and Agroforestry Research Center, University of Missouri. Forty-three forages were grown under non-shade (100% of full sunlight), moderate shade (45%), and dense shade (20%) without competition for water and nutrients. Annual forage yield (g pot−1) was equal to or higher under moderate shade for all 43 forages and under dense shade for 31 forages than the non-shade control. Relative distance plasticity index (RDPI), a measure of a species’ adaptability to different environments, ranged from 0.104 to 0.567. Cool season grasses had the lowest RDPI (0.183), followed by warm season grasses (0.252), warm season legumes (0.274), and cool season legumes (0.314), indicating grasses tend to be more shade tolerant than legumes in terms of forage yield. Overall, most grass and legume forages have the potential to produce equivalent or higher yields in agroforestry practices featuring light to moderate shade than forages in open pastures when competition from tree roots is minimized.

1.Recent studies unravelled the effect of climate changes on populations through their impact on functional traits and demographic rates in terrestrial and freshwater ecosystems, but such understanding in marine ecosystems remains incomplete.2.Here, we evaluate the impact of the combined effects of climate and functional traits on population dynamics of a long-l ived migratory seabird breeding in the southern ocean: the black- browed albatross (Thalassarche melanophris, BBA). We address the following prospective question: “Of all the changes in the climate and functional traits, which would produce the biggest impact on the BBA population growth rate?”3.We develop a structured matrix population model that includes the effect of cli-mate and functional traits on the complete BBA life cycle. A detailed sensitivity analysis is conducted to understand the main pathway by which climate and func-tional trait changes affect the population growth rate.4.The population growth rate of BBA is driven by the combined effects of climate over various seasons and multiple functional traits with carry- over effects across seasons on demographic processes. Changes in sea surface temperature (SST) during late winter cause the biggest changes in the population growth rate, through their effect on juvenile survival. Adults appeared to respond to changes in winter climate conditions by adapting their migratory schedule rather than by modifying their at- sea foraging activity. However, the sensitivity of the population growth rate to SST affecting BBA migratory schedule is small. BBA foraging activ-ity during the pre- breeding period has the biggest impact on population growth rate among functional traits. Finally, changes in SST during the breeding season have little effect on the population growth rate.5.These results highlight the importance of early life histories and carry- over ef-fects of climate and functional traits on demographic rates across multiple sea-sons in population response to climate change. Robust conclusions about the roles of various phases of the life cycle and functional traits in population response to climate change rely on an understanding of the relationships of traits to demo-graphic rates across the complete life cycle.

To develop a finescale dataset for the purpose of analyzing historical climatic change over the Tibet Plateau (TP), a high-resolution regional climate simulation for 1979–2011 was conducted using the Weather Research and Forecasting (WRF) Model driven by the ERA-Interim (ERA-Int). This work evaluates the high-resolution (30 km) WRF simulation in terms of annual variation, spatial structure, and 33-yr temporal trends of surface air temperature (Tair) and precipitation (Prec) over the TP, with reference to station observations. Another focus is on the examination of the height–temperature relationship. Inheriting from its forcing, the WRF simulation presents an apparent cold bias in the TP. The cold bias is largely reduced by a lapse rate correction of the simulated surface air temperature with help of the station and model elevations. ERA-Int presents the same sign of Tair and Prec trends as the observations, but with smaller magnitude, especially in the dry season. Compared to its forcing, the WRF simulation improves the simulation of the annual cycles and temporal trends of Tair and Prec in the wet season. In the dry season, however, there is hardly any improvement. The observed Tair presents a downward linear trend in the lapse rate. This feature is examined in the WRF simulation in comparison to ERA-Int. The WRF simulation captures the observed lapse rate and its temporal trend better than ERA-Int. The decreasing lapse rate over time confirms that Tair change in the TP is elevation dependent.

We provide an assessment of future daily characteristics of African precipitation by explicitly comparing the results of large ensembles of global (CMIP5, CMIP6) and regional (CORDEX, CORE) climate models, specifically highlighting the similarities and inconsistencies between them. Results for seasonal mean precipitation are not always consistent amongst ensembles: in particular, global models tend to project a wetter future compared to regional models, especially over the Eastern Sahel, Central and East Africa. However, results for other precipitation characteristics are more consistent. In general, all ensembles project an increase in maximum precipitation intensity during the wet season over all regions and emission scenarios (except the West Sahel for CORE) and a decrease in precipitation frequency (under the Representative Concentration Pathways RCP8.5) especially over the West Sahel, the Atlas region, southern central Africa, East Africa and southern Africa. Depending on the season, the length of dry spells is projected to increase consistently by all ensembles and for most (if not all) models over southern Africa, the Ethiopian highlands and the Atlas region. Discrepancies exist between global and regional models on the projected change in precipitation characteristics over specific regions and seasons. For instance, over the Eastern Sahel in July–August most global models show an increase in precipitation frequency but regional models project a robust decrease. Global and regional models also project an opposite sign in the change of the length of dry spells. CORE results show a marked drying over the regions affected by the West Africa monsoon throughout the year, accompanied by a decrease in mean precipitation intensity between May and July that is not present in the other ensembles. This enhanced drying may be related to specific physical mechanisms that are better resolved by the higher resolution models and highlights the importance of a process-based evaluation of the mechanisms controlling precipitation over the region.

Most ecosystems have multiple predator species that not only compete for shared prey, but also pose direct threats to each other. These intraguild interactions are key drivers of carnivore community structure, with ecosystem‐wide cascading effects. Yet, behavioral mechanisms for coexistence of multiple carnivore species remain poorly understood. The challenges of studying large, free‐ranging carnivores have resulted in mainly coarse‐scale examination of behavioral strategies without information about all interacting competitors. We overcame some of these challenges by examining the concurrent fine‐scale movement decisions of almost all individuals of four large mammalian carnivore species in a closed terrestrial system. We found that the intensity of intraguild interactions did not follow a simple hierarchical allometric pattern, because spatial and behavioral tactics of subordinate species changed with threat and resource levels across seasons. Lions (Panthera leo) were generally unrestricted and anchored themselves in areas rich in not only their principal prey, but also, during periods of resource limitation (dry season), rich in the main prey for other carnivores. Because of this, the greatest cost (potential intraguild predation) for subordinate carnivores was spatially coupled with the highest potential benefit of resource acquisition (prey‐rich areas), especially in the dry season. Leopard (P. pardus) and cheetah (Acinonyx jubatus) overlapped with the home range of lions but minimized their risk using fine‐scaled avoidance behaviors and restricted resource acquisition tactics. The cost of intraguild competition was most apparent for cheetahs, especially during the wet season, as areas with energetically rewarding large prey (wildebeest) were avoided when they overlapped highly with the activity areas of lions. Contrary to expectation, the smallest species (African wild dog, Lycaon pictus) did not avoid only lions, but also used multiple tactics to minimize encountering all other competitors. Intraguild competition thus forced wild dogs into areas with the lowest resource availability year round. Coexistence of multiple carnivore species has typically been explained by dietary niche separation, but our multi‐scaled movement results suggest that differences in resource acquisition may instead be a consequence of avoiding intraguild competition. We generate a more realistic representation of hierarchical behavioral interactions that may ultimately drive spatially explicit trophic structures of multi‐predator communities.

Lianas exhibit peak abundance in tropical forests with strong seasonal droughts, the eco‐physiological mechanisms associated with lianas coping with water deficits are poorly understood. We examined soil water partitioning, sap flow, and canopy eco‐physiological properties for 99 individuals of 15 liana and 34 co‐occurring tree species in three tropical forests that differed in soil water availability. In the dry season, lianas used a higher proportion of deep soil water in the karst forest (KF; an area with severe seasonal soil water deficit (SSWD)) and in the tropical seasonal forest (TSF, moderate SSWD), permitting them to maintain a comparable leaf water status than trees in the TSF or a better status than trees in the KF. Lianas exhibited strong stomatal control to maximize carbon fixation while minimizing dry season water loss. During the dry period, lianas significantly decreased water consumption in the TSF and the KF. Additionally, lianas had a much higher maximum photosynthetic rates and sap flux density in the wet season and a lower proportional decline in photosynthesis in the dry season compared with those of trees. Our results indicated that access to deep soil water and strong physiological adjustments in the dry season together with active wet‐season photosynthesis may explain the high abundance of lianas in seasonally dry forests.

Despite growing interest in trait-based approaches to community assembly, little attention has been given to seasonal variation in trait distribution patterns. Mobile animals can rapidly mediate influences of environmental factors and species interactions through dispersal, suggesting that the relative importance of different assembly mechanisms can vary over short time scales. This study analyzes seasonal changes in functional trait distributions of tropical fishes in the Xingu River, a major tributary of the Amazon with large predictable temporal variation in hydrologie conditions and species density. Comparison of observed functional diversity revealed that species within wet-season assemblages were more functionally similar than those in dry-season assemblages. Further, species within wet-season assemblages were more similar than random expectations based on null model predictions. Higher functional richness within dry season communities is consistent with increased niche complementarity during the period when fish densities are highest and biotic interactions should be stronger; however, null model tests suggest that stochastic factors or a combination of assembly mechanisms influence dry-season assemblages. These results demonstrate that the relative influence of community assembly mechanisms can vary seasonally in response to changing abiotic conditions, and suggest that studies attempting to infer a single dominant mechanism from functional patterns may overlook important aspects of the assembly process. During the prolonged flood pulse of the wet season, expanded habitat and lower densities of aquatic organisms likely reduce the influence of competition and prédation. This temporal shift in the influence of different assembly mechanisms, rather than any single mechanism, may play a large role in maintaining the structure and diversity of tropical rivers and perhaps other dynamic and biodiverse systems.

The monsoon transitional zone (MTZ) is the interactional belt between humid and arid regions. This study examines the interannual variation of the MTZ rainy season withdrawal over China. A withdrawal index is firstly defined according to pentad mean precipitation data. The index shows pronounced interannual variations, with a significant dominant period around 2–4 years. When the withdrawal of the MTZ rainy season is later than normal, pronounced precipitation increase appears over the MTZ in August. Meanwhile, a significant anticyclonic anomaly appears over the tropical western North Pacific (WNP) and a marked atmospheric wave train is seen originating from the North Atlantic and flowing across Eurasia to East Asia. Both the anomalous anticyclone over the WNP and the negative geopotential height anomalies related to the Eurasian wave train around the MTZ contribute to the precipitation increase over the MTZ in August, and lead to the late withdrawal of the MTZ rainy season in China. It is showed that preceding winter El Niño-like events have a contribution to the generation of anticyclonic anomalies over the WNP. In addition, the northern tropical Atlantic (NTA) sea surface temperature (SST) warming, which is independent of the preceding winter El Niño, is found to play a crucial role in the formation of the WNP anticyclone and the Eurasian atmospheric wave train. The importance of the NTA SST anomalies on the MTZ rainy season withdrawal is also confirmed by a set of atmospheric general circulation model experiments.

The spatiotemporal variability and three-dimensional structures of mesoscale convective systems (MCSs) east of the U.S. Rocky Mountains and their large-scale environments are characterized across all seasons using 13 years of high-resolution radar and satellite observations. Long-lived and intense MCSs account for over 50% of warm season precipitation in the Great Plains and over 40% of cold season precipitation in the southeast. The Great Plains has the strongest MCS seasonal cycle peaking in May–June, whereas in the U.S. southeast MCSs occur year-round. Distinctly different large-scale environments across the seasons have significant impacts on the structure of MCSs. Spring and fall MCSs commonly initiate under strong baroclinic forcing and favorable thermodynamic environments. MCS genesis frequently occurs in the Great Plains near sunset, although convection is not always surface based. Spring MCSs feature both large and deep convection, with a large stratiform rain area and high volume of rainfall. In contrast, summer MCSs often initiate under weak baroclinic forcing, featuring a high pressure ridge with weak low-level convergence acting on the warm, humid air associated with the low-level jet. MCS genesis concentrates east of the Rocky Mountain Front Range and near the southeast coast in the afternoon. The strongest MCS diurnal cycle amplitude extends from the foothills of the Rocky Mountains to the Great Plains. Summer MCSs have the largest and deepest convective features, the smallest stratiform rain area, and the lowest rainfall volume. Last, winter MCSs are characterized by the strongest baroclinic forcing and the largest MCS precipitation features over the southeast. Implications of the findings for climate modeling are discussed.

Although it has long been recognized that many tropical birds do not share the same narrow breeding periods as temperate birds, conventional thinking considers tropical breeding seasons to be discrete periods generally governed by rainfall seasonality. We used a database of >31,000 captures of 104 species collected over 17 years in rainforest near Manaus, Brazil (2.5'S), to examine timing of breeding. The proportion of individuals with active incubation patches peaked at 7% in the dry season, from October through December. The peak was about twice as high as the lowest rate, in the late wet season (April—June). From 9 to 15 families and >20 species bred in every month. Many taxa did not conform to the general pattern, instead peaking in the wet season (e.g., Galbulidae, Sclerurinae, Grallariidae, and Formicariidae). Most well-sampled species, even those with strong seasonal peaks, bred at almost any time of year, a pattern also shown by some individual birds that were captured multiple times in breeding condition. Among the 10 species with >50 incubation patches, all bred in at least 9 months, and 7 bred in 11–12 months. Earlier results from the same data set showed extremely protracted molts that regularly overlapped breeding. Collectively, molt and breeding data suggest that the annual cycle of some equatorial birds, particularly suboscines, differs fundamentally from that of temperate species, with much less fixed timing of breeding.