China's urban forests: Growing carbon pool

Science China Press

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(a) Carbon stocks (Tg C) in different components of urban forests. Veg, vegetation; Eco, ecosystem. (b) Carbon stocks (Tg C) in existing (area of urban forest remaining unchanged) and new urban forests (urban forests converted from other land types). (c) Carbon sequestration rates (Tg C a−1) in China’s urban forests. (d) Carbon sink (Tg C) in China’s urban forests from 1995 to 2060 and the relative contributions of different components. The error bar represents the standard deviation

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Credit: ©Science China Press

This study is led by Weixiang Cai (College of Soil and Water Conservation Science and Engineering (Institute of Soil and Water Conservation), Northwest A&F University), Li Xu (Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences), and Prof. Nianpeng He (Key Laboratory of Sustainable Forest Ecosystem Management-Ministry of Education, Northeast Forestry University).

The researchers applied a forest carbon sequestration (FCS) model based on a classical logistic equation between forest age and biomass to estimate carbon sequestration rates (CSR) of urban forests in China from 2010 to 2060 under future climate scenarios. The results show that the urban area in China increased by 16.07 × 104 km2, with an average growth rate of 0.64 × 104 km2 a−1, The carbon sequestration rate (CSR) of China’s urban forests exhibited a pattern of initial increase followed by a decline, reaching its peak in 2015–2020. In total, China’s urban forests stored 522.7 ± 9.6 Tg C during 1995–2060, with 222.5 ± 6.6 Tg C and 300.2 ± 3.9 Tg C in vegetation and soil, respectively. The CSR of urban forests in China between 1995 and 2060 varied between 1.92 and 22.8 Tg C a−1, averaging 8.04 ± 0.15 Tg C a−1. Carbon sink increment efficiency index showed negative correlation with the levels of provincial development and was highest in the northwestern provinces.

Their findings present a comprehensive assessment of the carbon sink dynamics in China urban forests and provide new insights into the formulation of coordinated urban planning and carbon management policies with the development of socio-economic levels in China.

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Journal

Science Bulletin

DOI

10.1016/j.scib.2025.06.015 

Method of Research

Case study

In this study, China is divided into four regions according to the development level of the province: (Ⅰ) Northwest, including Heilongjiang, Liaoning, and Jilin; (Ⅱ) West, including Xinjiang, Gansu, Xizang, Sichuan, Chongqing, Yunnan, Guizhou, Guangxi, Shaanxi, and Inner Mongolia; (Ⅲ) Central, including Shanxi, Henan, Anhui, Hubei, Hunan, and Jiangxi; and (Ⅳ) East, including Hebei, Beijing, Tianjin, Shandong, Jiangsu, Shanghai, Zhejiang, Fujian, Guangdong, and Hainan. (b) Different letters indicate significant differences at the P = 0.05 level

Credit

©Science China Press

New technology reveals migratory birds’ stunning precision in flight

Lund University

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A red-backed shrike is released after being fitted with a data logger at the hatching site in Gribskov, a forest in the north of the Danish island of Zealand. (Photo: Sissel Sjöberg)

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Credit: Sissel Sjöberg

Red-backed shrikes fly thousands of kilometres to reach Africa – and they do so with astonishing precision. Aided by new technology, researchers at Lund University in Sweden have been able to track the birds’ journeys in detail. It turns out that they may have a more complex genetic migration programme than researchers have previously been able to show.

“We can now follow a bird’s location throughout the year. How it got there and exactly how long it took. Each bird seems to follow a precise schedule with distinct stages – and the variation between individuals is surprisingly small,” says Sissel Sjöberg, evolutionary ecologist at Lund University.

Bird migration has long fascinated researchers around the world, but the details of how small migratory birds find their way across continents have been difficult to map out. Researchers already knew that birds’ migratory behaviour was partly down to inherited programmes that guide direction and distance on the route. Thanks to the new technology developed in Lund, researchers have been able to follow small birds’ flight in detail for the first time.

The measuring instruments, known as data loggers, weigh only one gram and can log the birds’ activity around the clock throughout the entire migration. This new data provides researchers with a previously unparallelled insight into exactly how the bird carries out the flight, something that has not previously been possible for small birds.

During the spring migration, total flying time differs by only six per cent between different individuals – despite them having flown around 270 hours over the course of 43 nightly flights and covering over 11,000 kilometres.

“The results provide us with new insights into how genetics may influence small birds’ long journeys across continents, and we may need to reconsider which components of migration birds inherit from their parents and how that works. Their genetic migration programme may be considerably more advanced than we previously thought,” says Sissel Sjöberg.

The study provides a new dimension to the way in which genetic programmes control animals’ behaviour and increase our understanding of how birds move across continents. Red-backed shrikes have turned out to be not so much adventurers as carefully prepared travellers – with a built-in flight plan that extends all the way from Skåne to southern Africa.

“It is an impressive achievement for a little bird that only weighs between 25 and 30 grams,” concludes Sissel Sjöberg.

 

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Journal

Proceedings of the Royal Society B Biological Sciences

DOI

10.1098/rspb.2025.0958 

Article Title

The structure of the annual migratory flight activity in a songbird

 

Risk to Amazon rainforest from land use and climate change

Ludwig-Maximilians-Universität München

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A new LMU study estimates that land use changes in conjunction with climate change could lead to the loss of up to 38 percent of the Amazon rainforest by the end of the 21st century.

The Amazon is the largest rainforest in the world. Its 5.5 million square kilometers are a hotspot of species diversity, a home for indigenous communities, and a lever for climate action. In biomass and soil, the rainforest stores a tenth of the entire carbon of terrestrial ecosystems. Through its enormous evaporative power, the Amazon forest draws moisture from the ocean into the interior of the country, where precipitation is constantly evaporating and raining down again. In this way, the forest keeps itself alive.

However, this also puts the Amazon rainforest at risk when arable land and livestock farming expand at the expense of forested areas, and when global warming causes droughts and heatwaves in the Amazon basin. Although both these factors – land use change and climate change – have already caused progressive damage, we have lacked clear knowledge of how they interacted and, above all, how the forested areas would develop in the future. Most concerning here are abrupt transitions from dense forest coverage to a savannah-like open landscape. If this happens on a large scale, it could create a tipping point at which the ecosystem would be irrevocably lost.

A team led by LMU geographer Selma Bultan has conducted the first analysis to systematically consider the effects of land use change and climate change in conjunction. Its results have just been published in the Proceedings of the National Academy of Sciences of the United States of America (PNAS). Using Earth system models with dynamic vegetation, the researchers analyzed deforestation in the Amazon basin from 1950 to 2014 and forecast future decline under two different climate scenarios. “Our analysis shows that up to 38 percent of the forest area which existed in 1950 could be lost by the end of the century, with 25 percent attributable to land use changes and 13 percent to rising temperatures,” explains Selma Bultan. “This would take us past the threshold of 20 to 25 percent, which earlier studies warned was the tipping point for the Amazon rainforest.”

Moreover, the team’s analyses show that the risk of an abrupt loss of forest area, as opposed to gradual decline, significantly increases when warming surpasses 2.3°C. “Based on current policies and definite commitments to climate action, we’re heading toward global warming of at least 2.5°C,” explains co-author Julia Pongratz, Professor of Physical Geography and Land Use Systems at LMU. “Positive developments such as the enhanced rainforest protections agreed at the climate conference in Belém need to be expanded, while we step up the pace of our fight against global warming. The value of the Amazon rainforest is much too great to put its existence on the line.”

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Journal

Proceedings of the National Academy of Sciences

DOI

10.1073/pnas.2418813122 

Article Title

Amazon forest faces severe decline under the dual pressures of anthropogenic climate change and land-use change

Article Publication Date

8-Dec-2025

A UCO study confirms the nutritional properties of acorns

University of Córdoba

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The researchers Marta Tienda Parrilla and María Dolores Rey

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Credit: University of Cordoba

The study also identifies the chemical compounds present in acorns, which could help determine which are best for consumption, thus boosting the consumption of an underutilized and undervalued food.

The holm oak is one of the most representative trees of Mediterranean forests and of the dehesa wooded pastureland system. Its fruit, the acorn, is used mainly to feed Iberian pigs. However, acorns continue to be an underused and often undervalued food, despite boasting nutritional properties making them highly valuable for human consumption. They stand out for their high starch content, a fatty acid profile similar to that of olive oil, an absence of gluten, and significant amounts of fiber and iron. They also contain a wide variety of phenolic compounds and other secondary metabolites with recognized antioxidant, anti-inflammatory, and antimicrobial activity, which underscores their potential as a healthy and functional food. This has been verified—consistent with previous studies—by the AGR-164 research group at the University of Cordoba, in collaboration with the Agroindustry and Food Quality group at the IFAPA Alameda del Obispo center, after analyzing the nutritional and nutraceutical profile of acorns of 14 specimens of holm oak.

Despite the favorable properties that acorns feature, they also present high variability, as the holm oak is a species that has not been domesticated. This is why there are as many types of acorns (bitter, sweet, large, small) as there are holm oaks. Because it is difficult—based on size or flavor alone—to identify the acorns most suitable for consumption, the team used various holistic and targeted techniques for the phytochemical characterization and identification of bioactive compounds in holm oak acorns.

Using several techniques—such as near-infrared spectroscopy (NIRS), colorimetric reactions, high-performance liquid chromatography (HPLC), and mass spectrometry (LC-MS/MS)—and despite having worked with a limited number of specimens, the team identified two main groups of acorns: large ones lacking bitterness, and medium-sized ones that are highly bitter. Among their most noteworthy characteristics are their high starch content, a predominance of unsaturated fatty acids, and elevated levels of calcium and sodium. Their metabolomic profiles proved to be highly specific to each tree, and several recently reported compounds with potential bioactive properties were detected.

A considerable number of metabolites of microbial origin were also identified, demonstrating the presence of a diverse microbiome associated with the seeds, which could even influence the acorns’ bitterness levels.

The study, published in the journal Future Foods and forming part of the doctoral dissertation by Marta Tienda Parrilla, marks a step toward facilitating the consumption of acorns as a human food source. Several lines of inquiry remain open, however. For example, researchers could evaluate which compounds found in acorns are beneficial to human health by determining their biological activity, or develop a catalogue of holm oaks with notable characteristics. Based on these selections, it would be possible to design domestication programs to produce trees with favorable genetic profiles, capable of yielding acorns suitable for human consumption in the future. This domestication would not entail selecting certain species at the expense of others, or eliminating genetic variability, but rather creating a catalogue of varieties accepted for consumption or for industrial use.

Reference

Marta Tienda-Parrilla, Cristina López-Hidalgo, Mónica Sánchez-Parra, José Luis Ordóñez-Díaz, José Manuel Moreno-Rojas, María-Ángeles Castillejo, Jesús V. Jorrín-Novo, María-Dolores Rey, “Phytochemical and metabolomics analysis of Quercus ilex acorns reveals substantial intraspecific variation, high nutritional and nutraceutical potential and rich associated microbiome,” Future Foods, Volume 12, 2025, 100754.

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Journal

Future Foods

DOI

10.1016/j.fufo.2025.100754 

Article Title

Phytochemical and metabolomics analysis of Quercus ilex acorns reveals substantial intraspecific variation, high nutritional and nutraceutical potential and rich associated microbiome