Contribution Of Climatic Factors Research Articles

Distinct Contributions of Climate Change and Anthropogenic Activities to Evapotranspiration and Gross Primary Production Variations over Mainland China

In recent decades, China has experienced substantial climate change and significant vegetation greenness due to the extensive implementation of artificial ecological restoration programs. However, the quantitative contributions of climatic and anthropogenic drivers to the national variations in associated evapotranspiration (ET) and gross primary productivity (GPP) over China at different climate zoning sub-regions remain unclear. Based on the analysis of climate factor and vegetation disturbance trends created by anthropogenic activities, this study constructed a remote sensing-based ecological model consisting of Penman–Monteith–Leuning (PML) and light use efficiency (LUE) components. The proposed model simulated the spatiotemporal changes in ET and GPP between 1999 and 2018 over China. The contributions of climatic factors and anthropogenic activities to ET and GPP variations were quantitatively calculated by ridge regression. The results show that (1) both interannual ET and GPP markedly increased, by 1.32 mm yr−1 and 8.01 g C m−2 yr−1, respectively; (2) vegetation changes due to anthropogenic disturbance made the dominant contribution to GPP variations over China, while the dominant factor influencing ET changes differed by sub-region due to the joint effects of vegetation and climate; (3) temperature and precipitation positively affected ET, while wind speed, humidity, and solar radiation negatively contributed to ET in most parts of Mainland China. These findings may provide a workable, scientific reference for further ecological restoration decision-making processes in China.

Contribution of Climatic Factors and Human Activities to Vegetation Changes in Arid Grassland

Clarifying the changing trend in vegetation and its affecting variables is extremely valuable for natural resource management. Vegetation changes in the Yinshanbeilu grassland region, which is situated in the centre of Inner Mongolia in northern China and is part of the arid steppe region, are extremely sensitive to climatic factors. In this study, we investigated the changes in vegetation in the Yinshanbeilu grassland zone from the year 2000 to 2020 using the Normalized Difference Vegetation Index (NDVI) data. The contribution of climatic conditions and human activities to the annual and growing season vegetation changes was quantified. The findings revealed that vegetation cover in the Yinshanbeilu grassland zone increased at a rate of 0.00267/a between 2000 and 2020. Throughout the year and during the growing season, precipitation had a greater influence on the growth of vegetation than other climatological factors. In most places, there was a significant positive correlation between the NDVI and precipitation, which negatively correlated with other climatic factors. The average rates at which precipitation, temperature, cumulative sunshine hours, and potential evapotranspiration contributed to changes in NDVI were 0.00173/a, −0.00027/a, 0.00006/a, and 0.00074/a, respectively, for the entire year, and 0.00180/a, −0.00001/a, 0.00021/a, and 0.00059/a for the growing season. The impact of climate change on vegetation activities was more pronounced, accounting for 84.76% of annual NDVI change and 97.36% of growing season NDVI change. Humans contributed 15.24% of total annual NDVI change and 2.64% of growing season NDVI change. This research’s findings serve as scientific support for preserving the environment in the Yinshanbeilu grassland region, as well as an essential reference for government decision making.

Quantifying the relative impacts of climate and human activities on vegetation change in Hunan Province between 2000 and 2015

Since1999, Hunan Province has embarked on a series of ecological projects to return farmland to forests across the province to explore the impacts of anthropogenic policies and actions on changes in vegetation cover between 2000 and 2015.It is important to understand the impacts of anthropogenic and climatic changes on regional vegetation cover change is an important guide for formulating reasonable environmental protection and restoration strategies in the region .this paper analysed the influence of climate and anthropogenic activities on the change of vegetation cover of Hunan Province during 2000-2015, which combined with an improved vegetation-climate residual regression model at the meta-scale. During 2000-2015, the contribution of anthropogenic activities to the increase of vegetation cover was 49%, 53%, 62% and 66% for unconverted forest land, grassland, unused land and water area respectively, while the contribution of climatic factors was 51%, 47%, 38% and 44% respectively. At the same time, all the land use types of contributions to vegetation cover change in Hunan Province is positive, and the land type without forest land change has the largest contribution to vegetation cover change in Hunan Province at 66.28%, while the land type where other land is converted to unused land has a lower contribution to vegetation cover change.

Assessment of the spatiotemporal evolution and driving forces of meteorological drought in the North China Plain

AbstractWith the changing trend of global temperature increase, the occurrence of drought events can no longer be ignored. An investigation of the spatiotemporal evolution characteristics of meteorological droughts and their responses to climatic variables can elucidate the mechanisms of the water cycle evolution in changing environments. In the present study, the standardized precipitation evapotranspiration index was used to characterize meteorological drought in the North China Plain (NCP) from 1970 to 2020. The spatiotemporal patterns of meteorological drought were analysed, and the contributions of climatic factors on annual and seasonal time scale drought evolution were determined. The results revealed that meteorological drought showed a decreasing trend (−0.07/10a) in the NCP from 1970 to 2020 and the most severe meteorological drought occurred in winter, with 56.56% of the region experiencing an increased drought trend in this season. Significant trends were identified for mean temperature (Tmean), temperature difference, and wind speed in the drought trend evolution. Precipitation (P) and Tmean were the primary controlling factors of the drought evolution. The strongest effect on drought change were exerted by P in spring (contribution [Con]: 1.57%), summer (Con: 1.79%) and autumn (Con: 2.43%), and the negative contribution of Tmean in winter (Con: −3.64%) was greater than the positive contribution of P (Con: 2.69%). The contribution of climatic variables to drought were increased by regional altitude difference. The results reveal a novel explanatory mechanism of climate change's effects on drought.

Quantification of Climate Factors Contributing to Variation of Oil Palm Yield

The yield of oil palm is heavily influenced by various climatic conditions, including rainfall (RF), radiation (Qs), temperature, and humidity. To quantify the impact of these factors, a study was conducted on a 15-year-old palm located in an oil palm estate in Pangkalan Lima Puluh Kota, West Sumatra, Indonesia. The study used climate data from 2011-2019 and yield data from 2015 and 2019. To determine the contribution of RF, Qs, and VPD / vapour pressure deficit, which was estimated from temperature and humidity, a computer-intensive importance metric developed by Lindemann, Merenda, and Gold (LMG metric) was utilized. The results showed that RF, Qs, and VPD collectively accounted for 50.16% of yield fluctuations at the study site. Furthermore, the contribution of climate factors on yield followed the order of VPD > Qs > RF.

Changes in the reference evapotranspiration and contributions of climate factors over the Indo–China Peninsula during 1961–2017

AbstractGiven the key roles of the Indo–China Peninsula (ICP) in weather and climate systems, hydrometeorology, and ecology, the annual and monthly changes in the Food and Agriculture Organization‐56 Penman–Monteith reference evapotranspiration (ET0), which was calculated based on the Climatic Research Unit datasets, were investigated in ICP during 1961–2017. The annual ICP ET0 significantly (p < .05) increased, with different increasing tendencies in most months. In particular, larger and more significant (p < .05) ET0 values were found during October–December. The annual and monthly ET0 changes showed evident spatial differences, characterized by increases in more than 50% of the ICP area except for decreases in around 70% of that area during March–May. A sensitivity experiment‐based separation method was utilized to evaluate the contribution of each influential factor, and the corresponding determinants were identified by comparing the contributions. Results showed that the annual ICP ET0 increase was attributed to the increased vapour pressure deficit (Vpd). However, the annual determinants varied spatially, with net solar radiation (Rn) in the southern region of ICP, wind speed (Wnd) in the northeast, and Vpd in the remaining regions. The monthly ICP determinant was Wnd in January, March–May and December, and Vpd for the remaining months. Despite different spatial patterns of monthly dominants, Vpd and Wnd were the determinants with the most extensive distributions over ICP (>75% of ICP in total). The results of this study can significantly fulfil the research gap regarding the ICP ET0 changes and the underlying mechanisms. Meanwhile, this study provides fundamental and necessary information for protecting biodiversity and understanding hydrometeorological extreme events, thus promoting specific measures to sustain the ICP development.

Human impact, climate and dispersal strategies determine plant invasion on islands

AbstractAimBiological invasions are likely determined by species dispersal strategies as well as environmental characteristics of a recipient region, especially climate and human impact. However, the contribution of climatic factors, human impact, and dispersal strategies in driving invasion processes is still controversial and not well embedded in the existing theoretical considerations. Here, we study how climate, species dispersal strategies, and human impact determine plant invasion processes on islands distributed in all major oceans in the context of directional ecological filtering.LocationSix mountainous, tropical, and subtropical islands in three major oceans: Island of Hawai'i and Maui (Pacific), Tenerife and La Palma (Atlantic), and La Réunion and Socotra (Indian Ocean).TaxonVascular Plants.MethodsWe recorded 360 non‐native species in 218 plots along roadside elevational transects covering the major temperature, precipitation and human impact (i.e., road density) gradients of the islands. We collected dispersal strategies for a majority of the recorded species and calculated the environmental niche per species using a hypervolume approach.ResultsNon‐native species’ generalism (i.e., mean community niche width) increased with precipitation, elevation and human impact but showed no relationship with temperature. Increasing precipitation led to environmental filtering of non‐native species resulting in more generalist species under high precipitation conditions. We found no directional filtering for temperature but an optimum range of most species between 10 and 20°C. Niche widths of non‐native species increased with the prevalence of certain dispersal strategies, particularly anemochory and anthropochory.Main conclusionsPlant invasion on tropical and subtropical islands seems to be mainly driven by precipitation and human impact, while temperature seems to be of little importance. Furthermore, anemochory and anthropochory are dispersal strategies associated with large niche widths of non‐native species. Our study allows a more detailed look at the mechanisms behind directional ecological filtering of non‐native plant species in non‐temperature‐limited ecosystems.

Vegetation dynamics and its response to driving factors in typical karst regions, Guizhou Province, China

Analyzing the vegetation dynamics and its response to driving factors provides a vital reference for understanding regional ecological processes and ecosystem services. However, this issue has been poorly understood in karst areas. Taking Guizhou Province as a case study, based on the Normalized-Difference Vegetation Index of the Global Inventory Modeling and Mapping Studies and on meteorological data sets during 1982–2015, we evaluated vegetation dynamics and its response to climatic factors and human activities. We used several methods: the Mann-Kendall test, rescaled range analysis, partial correlation analysis, and residual analysis. The results are as follows: 1) the mean annual Normalized-Difference Vegetation Index was 0.46 and exhibited a significant increasing trend with a variation rate of 0.01/10a during 1982–2015 in Guizhou Province. The vegetation cover showed was spatially heterogeneous: High vegetation cover was distributed mainly in the center and western margin of the study area, while the other parts of the study area mainly distributed with low vegetation cover, although the vegetation cover was higher in the nonkarst areas than in the karst areas; 2) in general, the climate was getting warmer and drier in Guizhou Province during 1982–2015. Vegetation cover was positively correlated with temperature and negatively correlated with precipitation. Compared to precipitation, temperature was the dominant climatic factor impacting vegetation dynamics; 3) large-scale ecological restoration projects have obviously increased vegetation cover in Guizhou Province in recent years. The contribution of human activities to vegetation changes was 76%, while the contribution of climatic factors was 24%. In summary, compared to natural forces such as climatic factors and geographic parameters, human activities were the main factor driving the vegetation dynamics in Guizhou Province.

Spatiotemporal Evolution of Fractional Vegetation Cover and Its Response to Climate Change Based on MODIS Data in the Subtropical Region of China

The subtropical vegetation plays an important role in maintaining the structure and function of global ecosystems, and its contribution to the global carbon balance are receiving increasing attention. The fractional vegetation cover (FVC) as an important indicator for monitoring environment change, is widely used to analyze the spatiotemporal pattern of regional and even global vegetation. China is an important distribution area of subtropical vegetation. Therefore, we first used the dimidiate pixel model to extract the subtropical FVC of China during 2001–2018 based on MODIS land surface reflectance data, and then used the linear regression analysis and the variation coefficient to explore its spatiotemporal variations characteristics. Finally, the partial correlation analysis and the partial derivative model were used to analyze the influences and contributions of climate factors on FVC, respectively. The results showed that (1) the subtropical FVC had obvious spatiotemporal heterogeneity; the FVC high-coverage and medium-coverage zones were concentratedly and their combined area accounted for more than 70% of the total study area. (2) The interannual variation in the average subtropical FVC from 2001 to 2018 showed a significant growth trend. (3) In 76.28% of the study area, the regional FVC showed an increasing trend, and the remaining regional FVC showed a decreasing trend. However, the overall fluctuations in the FVC (increasing or decreasing) in the region were relatively stable. (4) The influences of climate factors to the FVC exhibited obvious spatial differences. More than half of all pixels exhibited the influence of the average annual minimum temperature and the annual precipitation had positive on FVC, while the average annual maximum temperature had negative on FVC. (5) The contributions of climate changes to FVC had obvious heterogeneity, and the average annual minimum temperature was the main contribution factor affecting the dynamic variations of FVC.

Anthropogenic impacts on the decreasing sediment loads of nine major rivers in China, 1954–2015

Over the past 60 years, because of the combined impacts of human activities and climate change, the sediment load of the nine major rivers (the Yellow, Yangtze, Pearl, Songhuajiang, Liaohe, Haihe, Huaihe, Qiantangjiang, and Minjiang rivers) in China has dropped by 85%, which had caused serious environmental problems such as reservoir siltation and estuary erosion. However, quantitatively evaluating the impact of different human activities on this decline is still an unsolved and complex problem. Based on a big new data set from 27 gauge stations and 469 meteorological stations, we established five methods to assess sediment loss of China's nine major rivers. During 1954–2015, the sediment load into the marginal seas via these nine rivers was characterized by a marked decline, from 1.95 Gt/yr (1954–1968) to 1.40 Gt/yr (1969–1985), 890 Mt/yr (1986–1998), 450 Mt/yr (1999–2003), and 310 Mt/yr (2004–2015), reflecting an 85% decrease between 1954–1968 and 2004–2015. The cumulative sediment load into the marginal seas was ~71.0 Gt, constituting ~7% of the global sediment load. The Yellow River, Yangtze River, Pearl River, and other six major rivers contributed 40.9 (58%), 22.9 (32%), 4.1 (6%), and 2.96 Gt (4%), respectively. We estimate that ~53.0 Gt of terrestrial sediment has been retained on the mainland China because of human activities, with reservoir trapping, water resource utilization, and water–soil conservation measures accounting for 45.5%, 29%, and 25.5% of the total, respectively. The contribution of climatic factors was assessed to be secondary. This drastic reduction in river sediment load could lead to a series of negative effects on deltas: decreased sediment delivery, coastal erosion, aggravated reaction to storm disasters, and most importantly, loss of new land for human use. In addition, the large amounts of sediment trapping by reservoirs over long periods will cause siltation that could reduce reservoir water storage capacity.

Understanding Terrestrial Water Storage Declining Trends in the Yellow River Basin

AbstractUnder dual impacts from climate change and human activities, the Yellow River Basin (YRB) of China suffers from droughts and water scarcity. Understanding variations of terrestrial water storage (TWS) over the YRB is significant and beneficial to regional water resources management and sustainable development. This study investigates TWS variations in the YRB using data sets from two solutions (RL05 and RL06) of the Gravity Recovery and Climate Experiment (GRACE) satellites, as well as from global land surface models (the NOAH model and Catchment Land Surface Model [CLSM]) and hydrology and water resources model (PCR‐GLOBWB). Annual terrestrial water storage anomalies (TWSA) variation patterns were tracked by introducing a weighed centroid analysis concept. Human water use was analyzed, and its importance to TWS changes was evaluated by using the random forest algorithm. Conclusions can be briefly summarized as follows: (1) The declining trend of TWS in the YRB from the RL06 solution is more negative than that from RL05; the TWS trend from the PCR‐GLOBWB model is more consistent with GRACE than with the NOAH model and CLSM at the basin level, and the three models all underestimate the declining trend of TWS in the midstream relative to the GRACE solutions. (2) Spatial weighed centroids of annual GRACE TWSA moved toward the headwater of the YRB during the 2003–2015 period, suggesting a wide gap of TWS between the upstream and downstream YRB; the TWSA time series well correlate with the long‐term accumulation of climatic water balance, but the connections became weak in the 2010–2015 period. (3) Groundwater withdrawals have been controlled according to the Water Resources Bulletin, but the stress may be partly shifted to surface water; the increasing trend of ecological and industrial surface water use is significant, following the agriculture water use. (4) For the entire YRB, groundwater use accounts for the majority of feature importance in modeling TWSA time series, and the contribution of climate factors is the least. Agricultural water use ranks first relative to other sectors for the YRB, followed by the ecological and industrial use. This study provides a first comparison of TWSA between the latest Center for Space Research (CSR) GRACE RL06 solution and the previous RL05 solution in the YRB. The results are expected to present a comprehensive picture of TWS variations in the YRB and the impacts from climate and human factors.

Carbon, nitrogen and phosphorus stoichiometry of five common herbaceous species across islands in the Yellow Sea and the East China Sea.

Understanding variation of carbon (C), nitrogen (N) and phosphorus (P) stoichiometry in common plant species across islands along a latitude gradient is insightful to reveal the adaptation strategies of plant species to environmental changes. Five common herbaceous species including Artemisia argyi, Setaira viridis, Humulus japonicus, Ophiopog onjaponicus, and Oxalis corniculata were sampled in 125 plots across nine islands in Eastern China. C, N and P contents in leaves, stems, and roots of five plant species were measured, and their relationships with soil C, N and P contents as well as mean annual air temperature (MAT) and mean annual precipitation (MAP) were investigated. The results showed that the range of C, N and P contents in aboveground parts of five species across nine islands was 352.16-518.16, 10.81-34.43, 0.58-2.38 mg·g-1, while the range of C:N, N:P and C:P was 11.98-38.99, 4.67-27.47, 133.39-748.54, respectively. In terms of roots, the range of C, N and P contents of five species was 312.28-493.34, 9.26-23.27, 0.40-2.10 mg·g-1, while the range of C:N, N:P and C:P was 18.18-46.79, 8.53-37.38, 174.45-1120.40, respectively. With the increases of latitude, contents of N and P in aboveground parts increased, but N:P decreased. Relative to N content, P content showed higher variation and was largely dependent on environment. Climate factors explained 60% of the variation of N and P contents and N:P across nine islands. In contrast, N and P contents and N:P of roots were independent of latitude, with climatic factors only explained 6%-10% of their variations. The contribution of climatic factors and soil nutrients contributed to the variations of N and P contents differed between above ground parts and roots of five species. Soil N and P had significant effects on P content in roots. Soil P content was positively correlated to aboveground P content. Soil properties explained 37% of the variation in N and P contents of plant roots. Our results suggested that latitude-associated environment shifts were the main drivers of variation in N and P contents and N:P in aboveground parts, and soil nutrients especially affected variation in P in roots of five common plant species, when the effects of plant phylogeny was controlled.

Climatic changes and vulnerability of household food accessibility

PurposeSustainable food security at the household level is one of the emerging issues for all nations. Several factors such as social, economic, political, demographic, natural and livelihood strategies cause vulnerability in the status of household food security. This study aims to examine the vulnerability of the factors of household food accessibility and its linkage with the climatic changes in Malaysia.Design/methodology/approachThe study is based on primary data collected in the months of July-October, 2012, through a questionnaire survey on 460 low-income households from the East Coast Economic Region (ECER) in Malaysia. The samples were selected from E-Kasih poor household database, based on the cluster random sampling technique. The questionnaire uses a five-point Likert scale, and the data were analyzed using descriptive statistics and ANOVA F statistics for chi-square two-sample test.FindingsThe study finds that the vulnerability of the factors of household food accessibility has increased statistically and significantly over the past five years in Malaysia, whereas the contributions of climatic factors are low on these changes. This study suggests that the food security programs in Malaysia need to be integrated with the climatic change adaptation programs to ensure more effective and sustainable household food security in the future.Originality/valueThis study is an original work based on primary data that empirically measures the vulnerability of the factors of household food accessibility, one of the important dimensions of household food security, and its linkage with climatic changes.

Agricultural Policy, Climate Factors and Grain Output: Evidence From Household Survey Data in Rural China

This paper estimates a stochastic frontier function using a panel data set that includes 4 961 farmer households for the period of 2005–2009 to decompose the growth of grain production and the total factor productivity (TFP) growth at the farmer level. The empirical results show that the major contributor to the grain output growth for farmers is input growth and that its average contribution accounts for 60.92% of farmer's grain production growth in the period of 2006–2009, whereas the average contributions sourced from TFP growth and residuals are only 17.30 and 21.78%, respectively. The growth of intermediate inputs is a top contributor with an average contribution of 44.46%, followed by the planted area (18.16%), investment in fixed assets (1.05%), and labor input (−l2.75%), indicating that the contribution from the farmer's input growth is mainly due to the growth of intermediate inputs and that the decline in labor inputs has become an obstacle for farmers in seeking grain output growth. Among the elements consisting of TFP growth, the contribution of technical progress is the largest (32.04%), followed by grain subsidies (8.55%), the average monthly temperature (4.26%), the average monthly precipitation (−0.88%), the adjusted scale effect (−5.66%), and growth in technical efficiency (−21.01%). In general, the contribution of climate factors and agricultural policy factor are positive and significant.

Environmental factors and community dynamics at the southernmost part of the North American Graminetum – I. On the contribution of climatic factors to temporal variation in species composition

Compositional patterns of vegetation and their relationship to temporal and spatial environmental variation, with emphasis on climatic factors, were investigated in plant communities located in the southernmost portion of the North American Graminetum, in central Mexico. Data from 353 samples, obtained in four ecologically contrasting plant communities during 11 years, were analyzed by partial canonical correspondence analysis. Eight climatic variables and eighteen covariables (seventeen edaphic and one resource management) were included in the ordination. A relationship between floristic change and weather variation, once covariables effects were fitted, was examined. Despite a strong contrast in ecological conditions among study sites, a set of four climatic variables was finally found in which each variable contributed independently and statistically (P < 0.01) to the total variance in the vegetation data. Thus, environmental variables other than climatic could not conceal the important role of weather as a mediator of floristic change through time. Summer precipitation and summer maximum temperature showed the highest correlations with the first two species axes, 0.77 and –0.39, respectively. Contribution of these two climatic variables to variance in the vegetation data explained by environmental variables was approximately 81%. Annual species were abundant during rainy years, while abundance of perennial grasses and shrubs showed no clear relationship to weather variation. This study explicitly probes the important role of rain patterns in shaping structure and composition of semiarid communities and considers how other environmental factors can affect plant communities at the southernmost part of the North American Graminetum.