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As a fundamental element of global carbon storage, the storage carbon in terrestrial ecosystem is significant for climate change mitigation. Land use/cover change (LUCC) is a main impact element of ecosystems' carbon storage. Evaluating the relation between land use change and carbon storage is vital for lowering global carbon emissions. Taking Hainan Island as an example, this paper employs the InVEST as well as the CA-Markov models to assess and predict how different land use affects carbon storage in various situations from 2000 to 2020 and from 2030 to 2050 on Hainan Island. The influence factors, together with driving mechanisms of carbon storage spatial distribution are quantitatively analyzed as well in this paper. The results demonstrate that, from 2000 to 2020, Hainan Island's net increase in built land was 605.49 km2, representing a growth rate of 77.05%. Over the last 20 years, Hainan Island's carbon storage and density have decreased by 5.90 Tg and 1.75 Mg/hm2, respectively. The sharp rise in built land mainly makes the carbon storage decline. From 2030 to 2050, land use changes on Hainan Island are expected to result in differing degrees of carbon storage loss in various scenarios. In 2050, Hainan Island's carbon storage will decline by 17.36 Tg in the Natural Development Scenario (NDS), 13.61 Tg in the Farmland Protection Scenario (FPS), and 8.06 Tg in the Ecological Protection Scenario (EPS) compared to 2020. The EPS can efficiently maintain carbon sequestration capability, but it cannot effectively prevent cropland area loss. Regarding the carbon storage's spatial distribution, Hainan Island generally exhibits a pattern of high carbon storages in the low and middle carbon storages in the surrounding areas. Areas with high value are primarily located in Hainan Island's central and southern mountainous areas, whereas areas with low value are primarily located in surrounding areas with lower elevations, primarily encompassing built land and cropland. Geographic detection presented the spatial differentiation of carbon storage in Hainan Island is mainly influenced by factors like slope, land use intensity, and DEM, as well as its interaction with other factors is significantly strengthened (p < 0.05). Under the strategic framework of the "carbon peaking and carbon neutrality" goal and the national ecological civilization pilot zone, it is imperative to carefully consider scenarios for ecological protection and farmland protection, adopt ecological regulation models with spatial differentiation, and implement land use policies to improve ecosystem stability, which will contribute to carbon storage loss reduction and ensure food and ecological security. [ABSTRACT FROM AUTHOR]

After Bakun proposed his hypothesis in 1990 regarding upwelling under climate change, researchers conducted intensive studies to obtain the trends, current status, and future predictions of upwelling. Numerous studies have mainly focused on four major upwelling areas, which are part of the Eastern Boundary Upwelling System (EBUS). However, despite its importance, little attention has been given to the marginal seas upwelling areas such as the South China Sea (SCS), Arabian Sea, Baltic Sea, and other small-scale upwelling locations. Here, we combined several published studies to develop a new synthesis describing climate change impacts on these areas. There had been uncertainty regarding the intensification of upwelling, depending on the locations, data type, and method used. For the SCS, Vietnam and the northern SCS showed intensifying upwelling trends, while the Taiwan Strait showed a decreasing trend. Separate studies in eastern Hainan and the Arabian Sea (Somali and Oman) showed contrasting results, where both increasing and decreasing trends of upwelling had been recorded. Like the SCS, the Baltic Sea showed different results for different areas as they found negative trends along the Polish, Latvian and Estonian, and positive trends along the Swedish coast of the Baltic Sea and the Finnish coast of the Gulf of Finland. While small scales upwelling in La Guajira and southern Java showed increasing and decreasing trends, respectively. All of these limited studies suggest that researchers need to conduct a lot more studies, including the future projection of upwelling, by using climate models to develop a new understanding of how the upwelling in the SCS responds to climate change. [ABSTRACT FROM AUTHOR]

Understanding the water use efficiency (WUE) and adaptation strategies of plants in high-temperature and rainy areas is essential under global climate change. The leaf carbon content (LCC) and intrinsic WUE of 424 plant samples (from 312 plant species) on Hainan Island were measured to examine their relationship with geographical and climatic factors in herbs, trees, vines and ferns. The LCC ranged from 306.30 to 559.20 mg g−1, with an average of 418.85 mg g−1, and decreased with increasing mean annual temperature (MAT). The range of intrinsic WUE was 8.61 to 123.39 μmol mol−1 with an average value of 60.66 μmol mol−1. The intrinsic WUE decreased with increasing altitude and relative humidity (RH) and wind speed (WS), but increased with increasing latitude, MAT and rainy season temperature (RST), indicating that geographical and climatic factors affect the intrinsic WUE. Stepwise regression suggested that in tropical regions with high temperature and humidity, the change in plant intrinsic WUE was mainly driven by WS. In addition, the main factors affecting the intrinsic WUE of different plant functional types of plants are unique, implying that plants of different plant functional types have distinctive adaptive strategies to environmental change. The present study may provide an insight in water management in tropical rainforest. [ABSTRACT FROM AUTHOR]

As the world's largest reactive carbon reservoir, the ocean plays a critical role in global climate change. Among coastal plant ecosystems, mangroves have the highest carbon storage efficiency and are prone to the impact of anthropogenic activities. In this study, taking the mangrove wetland of Qinglan Bay as an example, we extracted information on mangrove coastal surface change from 1988 to 2020 based on multi-temporal Landsat remote sensing data through field ground surveys and laboratory analysis and used the InVEST model to calculate the spatial and temporal structure of blue carbon in the mangrove area to investigate the effects of mangrove change in an ecological restoration context. The result shows that the overall area of mangrove forests exhibited a decreasing trend from 1988 to 2020, and the area of mangroves decreased from 1559.34 ha to 737.37 ha of which 52.71% was transformed into aquiculture, construction, and farm land. Accordingly, the mangrove carbon sinks from 1988 to 2020 were significantly reduced and the carbon stock decreased at an annual tendency from 1,025,901.71 tons to 712,118.69 tons. With the implementation of mangrove restoration, the decline of mangrove forests has decreased since 2003, promoting the stabilization and enhancement of carbon sinks in the mangrove wetlands of Qinglan Bay. The results of this study provide a technical method to evaluate the carbon sink contribution of mangrove wetland restoration in Hainan Province, a scientific basis and methodological innovation to monitor the carbon sink of mangrove cover change in larger regions of China, a theoretical basis to select criteria for mangrove restoration, and a scientific and systematic management strategy for ecological and mangrove restoration on Hainan Island. [ABSTRACT FROM AUTHOR]

Aim: Mangrove forests are important coastal wetlands for the blue carbon budget and play a significant role in mitigating global climate change. However, spatial patterns of carbon stocks in mangrove forests on an island scale have not been quantified owing to methodological limitations and lack of understanding of controlling factors. We took the entire Hainan Island as a case study and aimed to carry out a comprehensive investigation of the spatial patterns and driving factors of carbon stocks in mangrove forests. Location: Southern China. Time period: 2017–2020. Major taxa studied: Mangrove forest. Methods: The upscaling method combined with field surveys and Sentinel‐2 imagery analysis were used to compare different models for optimization of mangrove ecosystem carbon stock estimations. We also used structural equation modelling (SEM) to evaluate the factors driving the distributional patterns of mangrove carbon stocks on an island scale. Results: The current total mangrove carbon stock of the entire Hainan Island was estimated to be 703,181 Mg C (with a mean density of 192 Mg C/ha), with the above‐ and below‐ground carbon stocks averaging at 44.7 and 147.3 Mg C/ha, respectively. The mangrove carbon storage in the north‐eastern region of the island was the highest and in the west region the lowest. Sediment nitrogen content and plant species diversity had the most positive driving effects on the distribution of total carbon stock for Hainan Island mangroves. Main conclusions: The combination of field surveys and Sentinel‐2 imagery analysis can be applied to regional‐scale estimations of carbon stocks for mangrove forests. Spatial pattens of mangrove carbon stocks vary among locations on Hainan Island, and soil nutrient (especially nitrogen) availability is the dominant factor regulating carbon stock variations along the land‐to‐sea gradient. Our findings have significant implications for better understanding the distribution of mangrove carbon stocks and quantification of the global blue carbon budget. [ABSTRACT FROM AUTHOR]

Abstract: Hainan province is the only tropical and island province in China, with the unique climatic and geographical features. It has a different energy performance in public buildings from those in the inland areas. This paper investigated the current situation of energy consumption of the sampled public buildings, including 26 hotels, 24 office buildings and 7 department stores, through analyzing utility billing data, on-site survey and measurement, and site operational records. The breakdowns of energy consumption found out that the electricity dominated the energy consumption for all the sampled buildings and the air conditioning system played a key role in the energy consumption of major building services. By analyzing the main factors for building energy consumption, the annual average energy use indexes were calculated to be 141.63kWh/m2, 87.70kWh/m2, and 166.95kWh/m2 for hotels, office buildings and department stores, respectively. Besides, the comparison between Hainan province and other areas revealed that the building energy consumption of this tropical province was at a low level. Because indoor environment quality can influence the health and work efficiency of humans in buildings, field tests on the indoor environment quality were also carried out, and the performance of indoor environment quality was rated. [Copyright &y& Elsevier]

Satellite observations reveal that China has been leading the global greening trend in the past 2 decades. We assessed the impact of land cover change as well as climate variability on total biogenic volatile organic compound (BVOC) emission in China from 2001–2016. We found the greening trend in China is leading a national-scale increase in BVOC emission. The BVOC emission level in 2016 could be 11.7 % higher than that in 2001 because of higher tree cover fraction and vegetation biomass. On the regional scale, the BVOC emission level from 2013–2016 could be 8.6 %–19.3 % higher than that from 2001–2004 in hotspots including (1) northeastern China, (2) Beijing and its surrounding areas, (3) the Qin Mountains, (4) Yunnan Province, (5) Guangxi–Guangdong provinces, and (6) Hainan island because of the land cover change without considering the impact of climate variability. The comparison among different scenarios showed that vegetation changes resulting from land cover management are the main driver of BVOC emission change in China. Climate variability contributed significantly to interannual variations but not much to the changing trend during the study period. In the standard scenario, which considers both land cover change and climate variability, a statistically significant increasing trend can still be found in regions including Beijing and its surroundings, Yunnan Province, and Hainan island, and BVOC emission total amount in these regions from 2013–2016 is 11.0 %–17.2 % higher that from 2001–2004. We compared the long-term HCHO vertical columns (VC) from the satellite-based Ozone Monitoring Instrument (OMI) with the estimation of isoprene emission in summer. The results showed statistically significant positive correlation coefficients over the regions with high vegetation cover fractions. In addition, the isoprene emission and HCHO VC both showed statistically significant increasing trends in the south of China where these two variables have high positive correlation coefficients. This result may support our estimation of the variability and trends of BVOC emission in this region; however, the comparison still has large uncertainties since the chemical and physical processes, including transportation, diffusion and chemical reactions, were not considered. Our results suggest that the continued increase in BVOC will enhance the importance of considering BVOC when making policies for controlling ozone pollution in China along with ongoing efforts to increase the forest cover fraction. [ABSTRACT FROM AUTHOR]

Zhao, Y.; Zou, X.; Liu, Q., and Chen, Y., 2019. Impacts of climate variability and human activities on streamflow in the Wanquan River Basin along the east coast of Hainan Island, southern China. Journal of Coastal Research, 35(2), 410–419. Coconut Creek (Florida), ISSN 0749-0208. The influences of climate change and human activities on streamflow change have received significant attention recently. In this study, daily data from seven precipitation gauges and one hydrological station are analyzed to assess the impacts of climate variability and human activities on streamflow over the past 54 years in the Wanquan River Basin (WRB). The Mann-Kendall test and Morlet wavelet method were employed to analyze the streamflow series, and the relative effects of climate change and human activities were empirically determined based on a coupled water and energy budget analysis. The results show that annual streamflow exhibited a statistically insignificant decreasing trend throughout the entire basin at an annual rate of –0.015 × 108 m3/y. Meteorological factors, such as temperature, exhibited significant increases throughout the entire basin. A decreasing trend in precipitation and an increasing trend in potential evapotranspiration were identified in the upstream region, whereas the opposite trends were observed in the downstream region. Moreover, an abrupt change in streamflow at Jiaji station occurred in 1974, exhibiting periodicities of 2 to 4 and 8 to 11 years at a 95% confidence level during the periods of 1965–80 and 1970–75, respectively. Regarding the catchment-averaged water balance, a quantitative analysis revealed that climate change resulted in an increase in streamflow from the 1970s to the 2000s throughout the entire basin, and streamflow increased by 146%, 259%, 473%, and 128% in the 1970s, the 1980s, the 1990s, and 2000–13 relative to streamflow in the 1960s. However, human activities may have decreased streamflow (–46%, –159%, –373%, and –28% in the 1970s, the 1980s, the 1990s, and 2000–13, respectively). Therefore, the relative effect of climate change was greater than that of human activities. Further research is needed to clarify the mechanisms associated with the anthropogenic effects on runoff changes. [ABSTRACT FROM AUTHOR]

Hainan Island is endowed with unique climatic and geographical conditions in China. Green orange is a characteristic fruit and plays an important role in local agricultural production of the island. However, few studies have been available regarding the climatic suitability index of green orange planting suitable regions in the island. Based on 30 years (1980 to 2019) of climatic data from 19 meteorological stations in the island, this study established spatial analysis models with topographical data, land use and GIS spatial analysis. Based on climate suitability function, this study established the climate suitability models of temperature, sunshine, precipitation, accumulated temperature and comprehensive suitability model for green orange planting. The Climate suitability index model for green orange planting suitable zoning areas was developed using a natural point segmentation method, and future climate change scenarios were adopted for evaluating the trends of climate suitable areas. The results revealed that the most suitable areas for planting green orange are mainly located at the eastern central region in the island. The climate suitability index ranged from 0.9 to 1.0 in the most suitable regions. The suitable area is mainly distributed in the eastern part, most of the central and western parts of the island, with the climate suitability index ranging from 0.7–0.9. However, the population density in the area is large, and the planting land is limited. The sub-suitable area is mainly located in the coastal areas of the western island, and the high-altitude areas in the central and western regions of the island, with the climate suitability index varying from 0.4 to 0.7. The unsuitable area is mainly distributed in the central mountainous area, with the climate suitability index being 0.0–0.4. The suitability of temperature showed decreasing trend, and the suitability of precipitation gradually moved from the east to the central region under future climate change scenarios. This study is helpful in promoting the development and utilization of agricultural resources and the fine zoning of green orange planting climate suitability in the island. [ABSTRACT FROM AUTHOR]

How mating system impacts the genetic diversity of plants has long fascinated and puzzled evolutionary biologists. Numerous studies have shown that self-fertilising plants have less genetic diversity at both the population and species levels than outcrossers. However, the phylogenetic relationships between species and correlated ecological traits have not been accounted for in these previous studies. Here, we conduct a comparative population genetic study of two closely related selfing and outcrossing Zingiber species, with sympatric distribution in Hainan Island, and obtain a result contrary to previous studies. The results indicate that selfing Z. corallinum can maintain high genetic diversity through differentiation intensified by local adaptation in populations across the species' range. In contrast, outcrossing Z. nudicarpum preserves high genetic diversity through gene exchange by frequent export of pollen within or among populations. Contrary to expectations, the major portion of genetic variation of outcrossing Z. nudicarpum may exist among populations, depending on the dispersal ability of pollen and seed. Our results also reveal that the main factor affecting population structure of selfing Z. corallinum is mountain ranges, followed by a moist climate, while that of outcrossing Z. nudicarpum is likely moisture, but not mountain ranges, due to gene flow via pollen. [ABSTRACT FROM AUTHOR]