Growing Season Precipitation Research Articles

The role of climate in the trend and variability of Ethiopia's cereal crop yields

Food security has been and will continue to be a major challenge in Ethiopia. The country's smallholder, rainfed agriculture renders its food production system extremely vulnerable to climate variability and extremes. In this study, we investigate the impact of past climate variability and change on the yields of five major cereal crops in Ethiopia—barley, maize, millet, sorghum, and wheat—during the period 1979–2014 using the Decision Support System for Agrotechnology Transfer (DSSAT) crop model. The model is calibrated at both the site and agroecological-zone scales. At the sites studied, the model results suggest that climate in the past four decades may have contributed to an increasing trend in maize yield, a decreasing trend in wheat yield, and no clear trend in the yields of barley and millet; cereal crop yield is positively correlated with growing season solar radiation and temperature, but negatively correlated with growing season precipitation. For modeled cereal crops across the nation during the study period, yield in western Ethiopia is positively correlated with solar radiation and day time temperature; in the eastern and southeastern Ethiopia where water is a limiting factor for growth, yield is positively correlated with precipitation but negatively correlated with solar radiation and both day time and night time temperature. The national average of simulated yields of most crops (except maize) showed an overall decreasing (although not statistically significant) trend induced by past climate variability and changes. Over a large portion of the highly productive areas where there is a negative correlation between yield and temperature, yield is simulated to have significantly decreased over the past four decades, an indication of adverse climate impact in the past and potential food security concern in the future.

Assessment of the relationship between ACL/CPI values of long chain n-alkanes and climate for the application of paleoclimate over the Tibetan Plateau

Leaf wax n-alkanes are one of the most abundant molecular biomarkers, and they have tremendous potential for climate study. To understand the relationship between distribution characteristics of terrestrial higher plant long chain n-alkanes and climate, we assessed the correlation between average chain length (ACL25-33)/carbon preference index (CPI25-33) and mean annual temperature (MAT), growing season temperature (GST), and mean annual precipitation (MAP) and growing season precipitation (GSP) over the Tibetan Plateau (TP). It is important to note that the distribution characteristics of these long chain n-alkanes must be determined in surface soils and surface lake sediments. Statistical analysis and multi-proxy approaches (CPI and Paq) were applied to deal with this problem. The answer was that the long-chain n-alkanes corresponding to the conditions (CPI25-33≥5, aquatic macrophyte versus aquatic macrophyte and terrestrial plant ratio Paq≤0.20) were basically derived from terrestrial higher plants. Using these long chain n-alkanes to assess the correlation between ACL25-33/CPI25-33 and MAT, GST, MAP and GSP, we concluded that (i) weak positive correlations between ACL25-33 and MAT/GST were observed on the TP. Under high temperatures, the ACL values of terrestrial higher plants will increase to reduce cuticular transpiration. (ii) there are negative relationships between CPI25-33 and MAP/GSP. (iii) based on the studies of two proxies (ACL and CPI) for paleoclimate application, the long-chain n-alkane ACL25-33 may become a useful qualitative indicator of temperature change in paleoclimate studies from Xining Basin, Ximen Co, Glacially eroded lake, and Lake Dangxiong Co on the TP. CPI25-33 values might serve as a qualitative indicator of precipitation in paleoclimate studies when the plant species do not vary on the TP.

An Assessment of Production Trends on the Great Plains from 1984 to 2017

Throughout the Great Plains, aboveground annual net primary productivity (ANPP) is a critical ecosystem service supporting billions of dollars of commerce and countless stakeholders. Managers and producers struggle with high interannual change in ANPP, which often varies 40% between years due to fluctuating precipitation and drought. To quantify ANPP trends and evaluate interannual and spatial variation, we created the Rangeland Production Monitoring Service (RPMS), a spatially explicit database with automatic annual updates of ANPP for all rangelands in the conterminous United States. The RPMS establishes relationships between normalized difference vegetation index (NDVI) from remote sensing data and ANPP from soil ecological site descriptions. These relationships were applied to NDVI data in each year from 1984 to present, although the present assessment focuses on the period from 1984 to 2017. Validation metrics include an r2 of 89% between predicted and observed ANPP at three locations in the Great Plains. For this special issue, we assess data from the RPMS to quantify trends and variation of ANPP in the Great Plains region for four major grassland types, smaller-scale ecological subsections, and national grassland units. Significant (α ≤ 0.05) increases in ANPP since 1984 were observed across all major grassland types in the Great Plains, particularly the northern mixed-grass prairie, which also had the greatest interannual variation (21%) from 1984 to 2017. Corresponding significant increases (P < 0.1) in growing season precipitation were found in all grassland types except the shortgrass steppe. Spatial variation decreases from west to east and tallgrass prairie exhibited the lowest temporal and spatial variation of 8% and 21%, respectively, from 1984 to 2017. Grazing allotments in the National Grasslands exhibit differential recovery after drought ranging from about 15% to 350%.

Qaidam Basin leaf fossils show northeastern Tibet was high, wet and cool in the early Oligocene

The Paleogene environment of today's semi-arid and arid Central Asia is poorly quantified and knowledge of the paleoelevation of northern Tibet remains elusive, yet both are crucially important for understanding inter-relationships between growth of the Tibetan Plateau and Asian monsoon development. Here, we apply the Climate-Leaf Analysis Multivariate Program (CLAMP) and moist enthalpy method to the newly discovered early Oligocene (30.8 Ma) fossil leaves from the Qaidam Basin, to reconstruct quantitatively the paleoclimate and paleoelevation of this critical part of northern Tibet. We find the Qaidam Basin floor vegetation was likely at ∼3.3 ± 1.4 km in the early Oligocene, similar to that of the present basin floor but higher than the rising Himalaya at that time, and experienced a temperate, moderately wet climate. Near-freezing (1.4 ± 3.5°C) winters accompanied cool summers (∼23 ± 2.9°C). Annual precipitation likely exceeded 1000 mm (growing season precipitation of 1229 ± 643 mm) with subdued (non-monsoonal) seasonality in which summers were drier than winters. This finding challenges geodynamic models that envisage a Miocene or later uplift of northern Tibet and progressive uplift from the south.

Nutrient addition increases grassland sensitivity to droughts.

Grasslands worldwide are expected to experience an increase in extreme events such as drought, along with simultaneous increases in mineral nutrient inputs as a result of human industrial activities. These changes are likely to interact because elevated nutrient inputs may alter plant diversity and increase the sensitivity to droughts. Dividing a system's sensitivity to drought into resistance to change during the drought and rate of recovery after the drought generates insights into different dimensions of the system's resilience in the face of drought. Here, we examine the effects of experimental nutrient fertilization and the resulting diversity loss on the resistance to and recovery from severe regional droughts. We do this at 13 North American sites spanning gradients of aridity, five annual grasslands in California, and eight perennial grasslands in the Great Plains. We measured rate of resistance as the change in annual aboveground biomass (ANPP) per unit change in growing season precipitation as conditions declined from normal to drought. We measured recovery as the change in ANPP during the postdrought period and the return to normal precipitation. Resistance and recovery did not vary across the 400-mm range of mean growing season precipitation spanned by our sites in the Great Plains. However, chronic nutrient fertilization in the Great Plains reduced drought resistance and increased drought recovery. In the California annual grasslands, arid sites had a greater recovery postdrought than mesic sites, and nutrient addition had no consistent effects on resistance or recovery. Across all study sites, we found that predrought species richness in natural grasslands was not consistently associated with rates of resistance to or recovery from the drought, in contrast to earlier findings from experimentally assembled grassland communities. Taken together, these results suggest that human-induced eutrophication may destabilize grassland primary production, but the effects of this may vary across regions and flora, especially between perennial and annual-dominated grasslands.

Soil moisture variations in response to precipitation in different vegetation types: A multi‐year study in the loess hilly region in China

AbstractVegetation restoration has been widely implemented as an effective approach to the control of soil erosion. However, severe soil desiccation is likely to occur if vegetation types and local precipitation conditions are not accounted for. In this study, an abandoned farmland and three typical vegetation types, including a natural shrubland, a plantation of black locust, and a natural oak secondary forest, were investigated to determine the characteristics of soil moisture in different hydrological years. The responses of soil moisture to precipitation were analysed at different timescales. Higher soil water contents were observed either in wet years or for natural vegetation types. The temporal response of soil moisture to precipitation was largely dependent on the timescale. At monthly scale, shallow soil moisture (0–100 cm) varied consistently with precipitation, whereas on interannual scale, precipitation is positively related to soil moisture along the whole profiles. Black locust and oak lands consumed more soil moisture than the shrubland, and severe soil desiccation developed in deep soil layers in the black locust plantation. The shrubland showed steeper regression slopes than other types for both the changes in soil water storage over time (ΔSWSt) versus the growing season precipitation and the difference in soil water storage with the abandoned farmland (ΔSWSv) versus the growing season precipitation, suggesting its higher adaptability to precipitation changes in this region. The results indicate that the shrubland develops optimal water use strategies through coevolution with local conditions and should be given precedence in vegetation restoration initiatives in this region.

Growing Season Precipitation Rather than Growing Season Length Predominates Maximum Normalized Difference Vegetation Index in Alpine Grasslands on the Tibetan Plateau

Precipitation and growing season length (GSL) are vital abiotic and biotic variables in controlling vegetation productivity in alpine regions. However, their relative effects on vegetation productivity have not been fully understood. In this study, we examined the responses of the maximum normalized difference vegetation index (NDVImax) to growing season precipitation (GSP) and GSL from 2000 to 2013 in 36 alpine grassland sites on the Tibetan Plateau. Our results indicated that NDVImax showed a positive relationship with prolonged GSL (R2 = 0.12) and GSP (R2 = 0.39). The linear slope of NDVImax increased with that of GSP rather than GSL. Therefore, GSP had a stronger effect on NDVImax than did GSL in alpine grasslands on the Tibetan Plateau.

Determining the impact of key climatic factors on geographic distribution of wild Akebia trifoliate

Abstract Based on the first-hand data of field investigation, existing literature, books and plant specimens database resources, the complete and available spatial database of wild Akebia trifoliate in China was established firstly. After analyzing the geographical distribution of Akebia trifoliate and its ecological factors, such as climate, soil and topographic characteristics, based on the existing literature, we selected 16 climatic indicators and used statistical analysis to study key climatic variables affecting its growth from a macro perspective. The results show that: (1) According to the characteristic roots and contribution rate obtained by principal component method, three principal factors are determined. Their corresponding value of three principal factors were 6.0538 and 37.84%, 4.7487 and 29.68%, 3.3822 and 21.14% respectively. All the characteristic roots indicate that the three principal factors are playing a dominant role in climate variables of influencing the distribution of Akebia trifoliate. (2) The first principal factor is called “heat factor”, the most important role determining geographical distribution of Akebia trifoliate, including the variables with larger factor load such as active accumulated temperature (≥10℃), warm index, biological temperature and annual average temperature. It shows that Akebia trifoliate tends to grow in areas with higher heat conditions. The second principal factor is called “humidity factor”, the second role for Akebia trifoliate, including the variables with larger factor load such as evapotranspiration rate, humidity index, annual precipitation, growing season precipitation and relative humidity. So it shows that Akebia trifoliate tends to be in areas with sufficient precipitation and high humidity. The third principal factor is called “illumination factor”, including the variables with larger load such as annual sunshine hours, growing season sunshine hours and extreme low temperature. So Akebia trifoliate likes the areas with relatively short sunshine hours. (3) Heat factor and humidity factor are the main limiting factors for its growth. The significant climatic variables offer a basis for the selection of ecological factors and the determination of weight in the suitability analysis of Akebia trifoliate. These results could provide a theoretical basis for the artificial cultivation of Akebia trifoliate. The ideas and methods for wild Akebia trifoliate in this paper could give a reference for the study of other valuable wild plants.

Multivariate Climate Field Reconstructions Using Tree Rings for the Northeastern United States

AbstractHigh‐resolution paleoclimate records are essential for improving our understanding of internal variability and the detection and attribution of forced climate system responses. The densely populated northeastern United States is at risk from increasing temperatures, severe droughts, and extreme precipitation, but the region has limited annual and seasonal‐resolution paleoclimate records beyond the instrumental record. Chamaecyparis thyoides, L. (B.S.P.), Atlantic white cedar, a wetland conifer found within 200 km of the Atlantic coastline of the United States, is a promising tree‐ring proxy that can fill in these data gaps. Here, we develop and analyze a new network of Atlantic white cedar tree‐ring chronologies across the northeastern United States and demonstrate that site selection is important for regional paleoclimate reconstructions. Ring width variability reflects winter through summer temperatures at inland and hydrologically stable sites in the northernmost section of the species' range. Ombrotrophic sites along the coast record hydrological signals and correlate with growing season precipitation. We demonstrate skillful regional climate field reconstructions for the last several centuries and show the increased skill from incorporating our moisture sensitive sites into broad‐scale products like the North American Drought Atlas. This comprehensive understanding of the species' climate responses leads to a tree‐ring network that provides the long‐term multivariate climate context at multidecadal and centennial time scales for the large‐scale ocean‐atmospheric processes that influence the climate of the region. We use this network to examine the covariance of temperature and drought across the New England area over the past two centuries.

Large-scale and local climatic controls on large herbivore productivity: implications for adaptive rangeland management.

Rangeland ecosystems worldwide are characterized by a high degree of uncertainty in precipitation, both within and across years. Such uncertainty creates challenges for livestock managers seeking to match herbivore numbers with forage availability to prevent vegetation degradation and optimize livestock production. Here, we assess variation in annual large herbivore production (LHP, kg/ha) across multiple herbivore densities over a 78-yr period (1940-2018) in a semiarid rangeland ecosystem (shortgrass steppe of eastern Colorado, USA) that has experienced several phase changes in global-level sea surface temperature (SST) anomalies, as measured by the Pacific Decadal Oscillation (PDO) and the El Niño-Southern Oscillation (ENSO). We examined the influence of prevailing PDO phase, magnitude of late winter (February-April) ENSO, prior growing-season precipitation (prior April to prior September) and precipitation during the six months (prior October to current April) preceding the growing season on LHP. All of these are known prior to the start of the growing season in the shortgrass steppe and could potentially be used by livestock managers to adjust herbivore densities. Annual LHP was greater during warm PDO irrespective of herbivore density, while variance in LHP increased by 69% (moderate density) and 91% (high density) under cold-phase compared to warm-phase PDO. No differences in LHP attributed to PDO phase were observed with low herbivore density. ENSO effects on LHP, specifically La Niña, were more pronounced during cold-phase PDO years. High herbivore density increased LHP at a greater rate than at moderate and low densities with increasing fall and winter precipitation. Differential gain, a weighted measure of LHP under higher relative to lower herbivore densities, was sensitive to prevailing PDO phase, ENSO magnitude, and precipitation amounts from the prior growing season and current fall-winter season. Temporal hierarchical approaches using PDO, ENSO, and local-scale precipitation can enhance decision-making for flexible herbivore densities. Herbivore densities could be increased above recommended levels with lowered risk of negative returns for managers during warm-phase PDO to result in greater LHP and less variability. Conversely, during cold-phase PDO, managers should be cognizant of the additional influences of ENSO and prior fall-winter precipitation, which can help predict when to reduce herbivore densities and minimize risk of forage shortages.

基于树木年轮定量重建过去50年贵州典型森林优势树种的地上生物量与生产力变化

PDF HTML阅读 XML下载 导出引用 引用提醒 基于树木年轮定量重建过去50年贵州典型森林优势树种的地上生物量与生产力变化 DOI: 10.5846/stxb201903250558 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金面上项目（31870462）；国家重点研发计划项目（2018YFC0507203，2016YFC0502101，2016YFC0502304） Reconstruction of above-ground biomass and net primary productivity of dominant tree species in Guizhou forests over past five decades based on tree-ring data Author: Affiliation: Fund Project: National Science Foundation of China (31870462) and National Basic Research Program of China (2018YFC0507203, 2016YFC0502101, 2016YFC0502304) 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:利用树木年轮宽度结合树木生物量方程，重建了贵州3个地区典型森林（2个常绿与落叶阔叶混交林和1个典型常绿阔叶林）6个优势树种（天龙山：化香树Platycarya strobilacea、安顺润楠Machilus cavaleriei；茂兰：化香树、马尾松Pinus massoniana；雷公山：华山松Pinus armandii、白梓树Pterostyrax psilophyllus）以树木个体为单元的地上生物量（AGB）与地上净初级生产力（ANPP）；比较了喀斯特与非喀斯特地区树木AGB与ANPP的差异；并研究了近50年气候变化对ANPP的影响。结果显示，针叶树的平均年轮宽度大于阔叶树，喀斯特地区针叶树和阔叶树的平均树木年轮宽度，分别小于非喀斯特地区针叶树和阔叶树的平均树木年轮宽度。喀斯特地区树木的AGB及其变异幅度均小于非喀斯特地区树木。近50年来，喀斯特地区阔叶树与针叶树的ANPP平均分别为（2.4±1.2）kg a-1 株-1和（4.6±4.1）kg a-1 株-1，显著低于非喀斯特地区阔叶树与针叶树的（5.6±4.8）kg a-1 株-1和（12.4±7.7）kg a-1 株-1。喀斯特地区树木ANPP的增长趋势与年均温的相关性高于生长季降水，非喀斯特地区树木ANPP与年均温和生长季降水均显著相关，且不管是在喀斯特还是在非喀斯特地区，针叶树ANPP对气候指标的变化比阔叶树更敏感。 Abstract:Tree-ring widths and allometric functions were used to reconstruct above-ground biomass (AGB) and net primary productivity (ANPP) of six dominant tree species (Tianlongshan Mt.: Platycarya strobilacea, Machilus cavaleriei; Maolan: Platycarya strobilacea, Pinus massoniana; Leigongshan Mt.: Pinus armandii, Pterostyrax psilophyllus) in three typical forests of Guizhou Province (karst evergreen and deciduous broadleaved mixed forests in two sites and another site of typical evergreen broadleaved forest). Similarity and dissimilarity of AGB and ANPP of different tree species, as well as the effects of climate change in the past five decades on ANPP were compared between karst and non-karst regions. The results showed that coniferous trees presented wider mean tree-ring widths than broadleaved trees. The mean ring-widths of coniferous trees and broadleaved trees in karst regions were narrower than those in non-karst region. The trees in karst regions indicated higher AGB and larger variation ranges than those in non-karst region. The ANPP of broadleaved trees and coniferous trees in karst regions were 2.4 ±1.2 kg a-1 individual-1 and 4.6 ±4.1 kg a-1 individual-1, respectively in the past five decades, which were significantly lower than those in non-karst region (5.6 ±4.8 kg a-1 individual-1 and 12.4±7.7 kg a-1 individual-1, respectively). Tree ANPP increase in karst regions was more related to mean annual temperature than growing season precipitation, and tree ANPP increase in non-karst region showed significant relationships with both mean annual temperature and growing season precipitation. ANPP of coniferous trees was more sensitive to climate change than that of broadleaved trees in both karst and non-karst regions. 参考文献 相似文献 引证文献

Estimating Annual Forage Yields with Plant Available Water and Growing Season Precipitation

Estimating Annual Forage Yields with Plant Available Water and Growing Season Precipitation

Growing-season temperature and precipitation are independent drivers of global variation in xylem hydraulic conductivity.

Stem xylem-specific hydraulic conductivity (KS ) represents the potential for plant water transport normalized by xylem cross section, length, and driving force. Variation in KS has implications for plant transpiration and photosynthesis, growth and survival, and also the geographic distribution of species. Clarifying the global-scale patterns of KS and its major drivers is needed to achieve a better understanding of how plants adapt to different environmental conditions, particularly under climate change scenarios. Here, we compiled a xylem hydraulics dataset with 1,186 species-at-site combinations (975 woody species representing 146 families, from 199 sites worldwide), and investigated how KS varied with climatic variables, plant functional types, and biomes. Growing-season temperature and growing-season precipitation drove global variation in KS independently. Both the mean and the variation in KS were highest in the warm and wet tropical regions, and lower in cold and dry regions, such as tundra and desert biomes. Our results suggest that future warming and redistribution of seasonal precipitation may have a significant impact on species functional diversity, and is likely to be particularly important in regions becoming warmer or drier, such as high latitudes. This highlights an important role for KS in predicting shifts in community composition in the face of climate change.

Assessing the impact of projected climate change on the future of grape growth and wine production in the Niagara Peninsula (Canada)

ABSTRACTThe impacts of projected climate change on several key climatic indicators for grape growth and wine production are assessed for the Niagara Peninsula (Canada). Global Climate Model outputs are evaluated and ranked for the study region to create selective ensembles of seasonal climate change projections. Statistical downscaling is performed to create local, daily, climate change scenarios. Average growing season temperature and the number of growing degree days have been increasing over time (1981–2010) and are projected to increase further under climate change (2011–2100). There were trends in total accumulated growing season precipitation or in the number of days with total precipitation greater than 10 mm, but slight increases were still projected under climate change. Minimum winter temperatures were warming over time and the number of days with temperatures below −20°C were decreasing, with both these trends projected to continue. There were no statistically significant trends associated with maximum summer temperatures or the number of days with temperatures above 30°C, but both were projected to increase considerably in the future. A warmer, wetter climate in the region is expected to lengthen growing seasons, increase growth potential, diminish risk of winter freeze damage, while increasing summer heat stress.

Integrating climate prediction and regionalization into an agro-economic model to guide agricultural planning

Advanced skill in seasonal climate prediction coupled with sectoral decision models can provide decision makers with opportunities to benefit or reduce unnecessary losses. Such approaches are particularly beneficial to rainfed agriculture, the livelihood choice for the majority of the world’s poor population, for which yields are highly sensitive to climate conditions. However, a notable gap still exists between scientific communities producing predictions and the end users who may actually realize the benefits. In this study, an interdisciplinary approach connecting climate prediction to agricultural planning is adopted to address this gap. An ex ante evaluation of seasonal precipitation prediction is assessed using an agro-economic equilibrium model to simulate Ethiopia’s national economy, accounting for interannual climate variability and prediction-guided agricultural responses. Given the high spatial variability in Ethiopian precipitation, delineation of homogeneous climatic regions (i.e., regionalization) is also considered in addition to growing season precipitation prediction. The model provides perspectives across various economic indices (e.g., gross domestic product, calorie consumption, and poverty rate) at aggregated (national) and disaggregated (zonal) scales. Model results illustrate the key influence of climate on the Ethiopian economy, and prospects for positive net benefits under a prediction-guided agricultural planning (e.g., reallocation of crop types) strategy, as compared with static business-as-usual agricultural practices.

Patterns of foliar and soil nitrogen isotope composition of Caragana microphylla, a leguminous shrub species in the semi-arid regions of northern China

Variation in foliar and soil nitrogen (N) isotope composition (δ15N) across environmental gradients has been widely studied at various scales. However, much less is known about the patterns of N2-fixing species that are presumed to be independent of climatic factors due to their capacity to fix atmospheric N2. In this study, the foliar and soil δ15N in Caragana microphylla, a leguminous shrub important for its role in controlling soil erosion and land desertification in northern China, were determined from 23 sites along an east–west transect across the species distribution range. The soil δ15N tended to be significantly higher than the foliar δ15N and there was a positive correlation between them (r2 = 0.58, p < 0.0001), though substantial variability was found in foliar and soil δ15N across all sites. Both soil and foliar δ15N were negatively correlated with precipitation, temperature, dry N deposition (DND) and longitude, but positively correlated with foliar N, soil N and altitude. The structural equation modeling further suggested growing season precipitation indirectly influenced foliar δ15N by its direct impact on soil δ15N and by its indirect impact on soil δ15N via DND and total N deposition (TND), whereas growing season temperature affected foliar δ15N indirectly both by its effect on foliar N and by its effect on soil δ15N via WND, TND and foliar N. Altogether, our results indicated that foliar δ15N also shifted along environmental gradients in leguminous plant species and showed primary dependence on soil δ15N, confirming previous findings in non-leguminous plants. These results augment our common understanding of foliar and soil δ15N patterns across climatic gradients in plants.

Clumped and stable isotopes of land snail shells on the Chinese Loess Plateau and their climatic implications

We report stable (δ13Cshell, δ18Oshell) and clumped isotope (Δ47) compositions of modern and last glacial fossil snail shell carbonates from the Luochuan and Weinan sections on the central and southern Chinese Loess Plateau (CLP). Our study reveals that the average Δ47 temperature (T47) of modern snails is consistent with monitored temperatures during the snail growing season at the studied locations and is ~10 °C higher than that of fossil snails from glacial time. Moreover, the average δ13Cshell of modern snails is more depleted than that of fossils. We argue that the δ13Cshell cannot record changes in plant communities (i.e., the C3/C4 ratio) on the CLP and may mainly indicate arid conditions with depleted values reflecting reduced aridity. Additionally, the reconstructed snail body water δ18O (δ18Owater) of modern snails is more enriched than δ18O in modern growing season precipitation and δ18Owater of fossils. This contrast may be related to the high degree of evaporative enrichment of environmental water 18O in the body/ingested by modern snails under warm conditions. Therefore, we suggest that using δ18Oshell to directly reconstruct the oxygen isotopes of precipitation is difficult and that higher δ18Oshell and δ18Owater values probably indicate higher environmental temperature/stronger evaporative enrichment on glacial-interglacial timescales on the CLP.

Impact of Climate Change on the Growth of Typical Crops in Karst Areas: A Case Study of Guizhou Province

Climate change has emerged as a significant man-made global environmental challenge marked by rising temperature. The global rising temperature is supposed to alter climatic patterns like floods and droughts, thereby affecting human life supporting system and global food production. In order to clarify the impact of weather events on agricultural production in karst landforms, this study selected the indices of the growth period of crops (start time and duration), growing season precipitation, intense precipitation, number of consecutive rainless days, and number of drought-flood abrupt alternation events to evaluate the variation trend of future weather events and their impact on crop growth in Guizhou Province, China. The results show that (1) the climate is generally getting warmer. From 2019 to 2050, the sowing period of winter wheat and rice tends to be postponed. The duration of maize and rice’s growth period will be shortened, and the life cycle of wheat also emerges as having a decreasing tendency except for those from the southern region. Comparing with the mean value during 1961 to 2018, the average crop cycle length of winter wheat, summer maize, and rice was shortened. The rate of shortening of crop cycle length is faster than the value during 1961 to 2018. (2) In the next 30 years, extreme precipitation concentrates in June and mainly falls in the central and southeast parts of Guizhou Province. In addition, summer is the outbreak period of drought events and drought-flood abrupt alternation events, which has a great impact on crop’s growth. This study can provide references for the planting system, structure, layout, and management of crops in the karst region.

Comparing independent climate-sensitive models of aboveground biomass and diameter growth with their compatible simultaneous model system for three larch species in China

Accurate estimate of tree biomass is essential for forest management. In recent years, several climate-sensitive allometric biomass models with diameter at breast height [Formula: see text] as a predictor have been proposed for various tree species and climate zones to estimate tree aboveground biomass (AGB). But the allometric models only account for the potential effects of climate on tree biomass and do not simultaneously explain the influence of climate on [Formula: see text] growth. In this study, based on the AGB data from 256 destructively sampled trees of three larch species randomly distributed across the five secondary climate zones in northeastern and northern China, we first developed a climate-sensitive AGB base model and a climate-sensitive [Formula: see text] growth base model using a nonlinear least square regression separately. A compatible simultaneous model system was then developed with the climate-sensitive AGB and [Formula: see text] growth models using a nonlinear seemingly unrelated regression. The potential effects of several temperature and precipitation variables on AGB and [Formula: see text] growth were evaluated. The fitting results of climatic sensitive base models were compared against those of their compatible simultaneous model system. It was found that a decreased isothermality ([mean of monthly (maximum temperature-minimum temperature)]/(Maximum temperature of the warmest month-Minimum temperature of the coldest month)) and total growing season precipitation, and increased annual precipitation significantly increased the values of AGB; an increase of temperature seasonality (a standard deviation of the mean monthly temperature) and precipitation seasonality (a standard deviation of the mean monthly precipitation) could lead to the increase of [Formula: see text]. The differences of the model fitting results between the compatible simultaneous system with the consideration of climate effects on both AGB and [Formula: see text] growth and its corresponding climate-sensitive AGB and [Formula: see text] growth base models were very small and insignificant [Formula: see text]. Compared to the base models, the inherent correlation of AGB with [Formula: see text] was taken into account effectively by the proposed compatible model system developed with the climate-sensitive AGB and [Formula: see text] growth models. In addition, the compatible properties of the estimated AGB and [Formula: see text] were also addressed substantially in the proposed model system.

Asymmetric responses of plant community structure and composition to precipitation variabilities in a semi-arid steppe.

Changing precipitation regimes can profoundly affect plant growth in terrestrial ecosystems, especially in arid and semi-arid regions. However, how changing precipitation, especially extreme precipitation events, alters plant diversity and community composition is still poorly understood. A 3-year field manipulative experiment with seven precipitation treatments, including - 60%, - 40%, - 20%, 0% (as a control), + 20%, + 40%, and + 60% of ambient growing-season precipitation, was conducted in a semi-arid steppe in the Mongolian Plateau. Results showed total plant community cover and forb cover were enhanced with increased precipitation and reduced under decreased precipitation, whereas grass cover was suppressed under the - 60% treatment only. Plant community and grass species richness were reduced by the - 60% treatment only. Moreover, our results demonstrated that total plant community cover was more sensitive to decreased than increased precipitation under normal and extreme precipitation change, and species richness was more sensitive to decreased than increased precipitation under extreme precipitation change. The community composition and low field water holding capacity may drive this asymmetric response. Accumulated changes in community cover may eventually lead to changes in species richness. However, compared to control, Shannon-Weiner index (H) did not respond to any precipitation treatment, and Pielou's evenness index (E) was reduced under the + 60% treatment across the 3year, but not in each year. Thus, the findings suggest that plant biodiversity in the semi-arid steppe may have a strong resistance to precipitation pattern changes through adjusting its composition in a short term.