Spatiotemporal variability of reference evapotranspiration and its contributing climatic factors in Yunnan Province, SW China, 1961–2004

Abstract

Questions: Density-dependent processes may promote species diversity in plant communities. Here, we tested whether seedling survival was density-dependent and varied by seedling size, species and climatic factors. Location: Tropical rain forest, Xishuangbanna, southwest China. Methods: Generalized linear mixed-effects models were used to examine seedling survival (232 tree species) across 9 years of seedling census data from a 20-ha tropical forest dynamics plot. Our predictor variables were conspecific and heterospecific neighbour density, size of the seedling and annual variation in climatic factors. Results: We found significant negative effects of conspecific tree density, but positive effects of heterospecific seedling density on the survival of tree seedlings in this plot. In general, conspecific negative density dependence (CNDD) was observed most frequently for large size classes of seedlings (≥20-cm high), while heterospecific positive density dependence (HPDD) was similar at all size classes. CNDD for large seedlings was stronger during warm years, and HPDD for large seedlings was stronger during dry years. Conclusions: Our study suggests that the strength of density dependence varied through time, and this strength was influenced by water availability and temperature. Our results highlight the potential for changes in species composition and species coexistence that could result from increasing temperature-strengthening CNDD effects and decreasing precipitation strengthening HPDD effects.

Changes of Reference Evapotranspiration and Its Relationship to Dry/Wet Conditions Based on the Aridity Index in the Songnen Grassland, Northeast China

“…During the study period, the observed variations in Max T, Min T, and Ave T were similar to the global pattern of increasing minimum, mean, and maximum temperature [12]; and the results of the analysis of other climatic factors were consistent with the findings reported from Yunnan Province in southwest China during 1961-2004 [5]. There, the sensitivity analyses for changes in the annual ET 0 showed that Ave RH and Max T were the most sensitive climate variables over the whole Songnen Grassland, which was in agreement with Yin et al [44], who studied all of China during 1961-2008.…”

“…They are all distributed inside or adjacent to the study area in order to cover the entire region. All selected stations have good-quality data and meet the QA (Quality assurance)/QC (Quality control) requirements, which means that the spatial distribution of the stations had to cover the entire region, the time series had to be long enough to obtain statistically significant results in trend analyses, and the climate data was The FAO-56 Penman-Monteith (FAO-PM) equation was recommended as the sole and global standard method for ET 0 calculation [5,20]. The method has been widely verified for its accuracy and reliability in various climatologic zones around the world [21,22].…”

“…ET 0 is one of the vital components of the hydrological cycle and controls the energy and mass exchange between terrestrial ecosystems and the atmosphere [3,4]. It is influenced by many factors including climate factors (e.g., temperature, solar radiation), crop factors (e.g., crop pattern, cropping system), environmental conditions, and water resource management [5]. Changes in ET 0 affect agricultural production, water resource programming, and irrigation systems.…”

Climatic controls on watershed reference evapotranspiration vary dramatically during the past 50 years in southern China

“…The most influential factor in the changes of ETo was decreased R s in summer and growing season (Fig. 6b, e), the same as studies in Yunnan province of southwestern China (Fan and Thomas, 2012), subtropical and tropical regions in…”

Modeling the changes in water balance components of the highly irrigated western part of Bangladesh

“…Although the annual rainfall and temperature of the Satkhira station exhibited positive trends (Kamruzzaman et al, 2016a), its P ET exhibited a significant decreasing trend. Increasing temperature and decreasing P ET trends were observed in the Yunnan Province of South China (Fan and Thomas, 2012). McVicar et al (2012) also found decreasing P ET trends in different parts of the world.…”