Exploring the relationship between land use/land cover and apparent temperature in China (1996-2020): implications for urban planning.

In recent decades, rising air temperatures (AT) and apparent temperatures (AP) have posed growing health risks. In the context of China's rapid urbanization and global climate change, it is crucial to understand the impact of urban land use/land cover (LULC) changes on AP. This study investigates the spatial distribution and long-term variation patterns of AT and AP, using data from 834 meteorological stations across China from 1996 to 2020. It also explores the relationship between AT, AP, and LULC in the urban core areas of 30 major cities. Study reveals that AT and AP exhibit overall high spatial similarity, albeit with greater spatial variance in AP. Notably, regions with significant disparities between the two have been identified. Furthermore, it's observed that the spatial range of high AP change rates is wider than that of AT. Moreover, the study suggests a potential bivariate quadratic function relationship between ΔT (the difference between AT and AP) and Wa_ratio and Ar_ratio, indicating the presence of a Least Suitable Curve (LSC), [Formula: see text]. Urban LULC planning should carefully avoid intersecting with this curve. These findings can provide valuable insights for urban LULC planning, ultimately enhancing the thermal comfort of urban residents.

Phylogeography of cultivated and wild ophiopogon japonicus based on chloroplast DNA: exploration of the origin and sustainable cultivation.

BACKGROUND: Ophiopogon japonicus, mainly planted in Sichuan (CMD) and Zhejiang (ZMD) province in China, has a lengthy cultivation history. During the long period of domestication, the genetic diversity of cultivated O. japonicus has substantially declined, which will affect the population continuity and evolutionary potential of this species. Therefore, it is necessary to clarify the phylogeography of cultivated O. japonicus to establish a theoretical basis for the utilization and conservation of the genetic resources of O. japonicus. RESULT: The genetic diversity and population structure of 266 O. japonicus individual plants from 23 sampling sites were analyzed based on 4 chloroplast DNA sequences (atpB-rbcL, rpl16, psbA-trnH and rpl20-5'rps12) to identify the effects of domestication on genetic diversity of cultivars and determine their geographic origins. The results showed that cultivated O. japonicus and wild O. japonicus had 4 and 15 haplotypes respectively. The genetic diversity of two cultivars (Hd = 0.35700, π = 0.06667) was much lower than that of the wild populations (Hd = 0.76200, π = 0.20378), and the level of genetic diversity in CMD (Hd = 0.01900, π = 0.00125) was lower than that in ZMD (Hd = 0.06900, π = 0.01096). There was significant difference in genetic differentiation between the cultivated and the wild (FST = 0.82044), especially between the two cultivars (FST = 0.98254). This species showed a pronounced phylogeographical structure (NST > GST, P < 0.05). The phylogenetic tree showed that the genetic difference between CMD and ZMD was not enough to distinguish the cultivars between the two producing areas by using O. amblyphyllus Wang et Dai as an outgroup. In addition, both CMD and ZMD have a closer relationship with wild populations in Sichuan than that in Zhejiang. The results of the TCS network and species distribution model suggested that the wild population TQ located in Sichuan province could serve as the ancestor of cultivated O. japonicus, which was supported by RASP analysis. CONCLUSION: These results suggest that cultivated O. japonicus has experienced dramatic loss of genetic diversity under anthropogenic influence. The genetic differentiation between CMD and ZMD is likely to be influenced by founder effect and strong artificial selection for plant traits. It appears that wild populations in Sichuan area are involved in the origin of not only CMD but also ZMD. In addition, we also raise some suggestions for planning scientific strategies for resource conservation of O. japonicus based on its genetic diversity and population structure.

The evaluation of N/P fate using the SPARROW model: a case study in an arid and semi-arid region, northern China.

The assessment of nutrients' fate from source to sink is critical to water quality control. As an important ecological reserve in the arid and semi-arid regions of China, the Luanhe River Basin (LRB) has suffered from the deterioration of water quality, thus leading to the urgent management and control. However, few studies have devoted to exploring the fate of N/P contaminations for the entire watershed, due possibly to the large drainage area and heterogeneous watershed composition. Here, we attempt to illustrate N/P contaminations delivery and retention processes using the SPAtially Referenced Regression On Watershed attributes (SPARROW) model. The model reveals 97% of the spatial variability in the TN load and 81% in the TP load, verifying its availability and credibility. The results indicate that anthropogenic sources are dominating the N/P load, which account for 68.5% of N and 74.6% of P inputs. The results highlight the significant retention effects of streams and reservoirs, with 16.4% of N and 13.4% of P removals by streams and 24.3% of N and 10.7% of P removals by reservoirs, respectively. Ultimately, only 49,045.2 t yr-1 (or 16.9%) of N and 1668.7 t yr-1 (or 17.1%) of P being transported to the Bohai Sea. In addition, the analysis of influencing factors showed that regional characteristics (e.g., topography, rainfall), stream size, and delivery distance are potential factors affecting the riverine transport, whereas flow rate and surface area are primarily affecting the reservoirs attenuation. In the future, the watershed water quality management should pay more attention to source management and pollution legacy risks to achieve sustainable and healthy watershed development.