Ecosystem Services Evaluation of Karst New Urban Areas Based on Net Primary Productivity of Guanshanhu District, Guiyang, Guizhou Province, China

Net Primary Productivity (NPP) is the basis of the material and energy transport calculation in ecosystem studies. NPP directly reflects the production capacity of plant communities under natural conditions. Ecosystem services are hot topics in the field of ecology. Many studies calculate ecosystem service value based on NPP. Taking Guanshanhu District of Guiyang City, Guizhou Province as the research object, using TM, ETM+, Gaofen2 and MOD17A3HGF.006 as data sources, this paper analyzed the change of ecosystem service value based on NPP in 2000, 2010 and 2020. The results showed that the area of forest ecosystem increased during 2000-2010 and decreased during 2010-2020. The artificial surface grew rapidly from 1146.82 hm2 to 7544.29 hm2 during 2000-2020. The farmland ecosystem decreased from 13308.29 hm2 to 6342.33 hm2 during 2000-2020. With the dynamic changes in ecosystem spatial distribution and component structure, the total NPP in 2000, 2010 and 2020 was 12.58 × 104 t, 11.90 × 104 t and 11.78 × 104 t, respectively, showing a decreasing trend. The total value of natural and semi-natural ecosystems services based on NPP showed an increasing trend, which was ￥ 6.938 × 108 in 2000, ￥ 8.052 × 108 in 2010 and ￥ 10.306 × 108 in 2020 respectively. The ecosystem contributed the most to the ecological service value in 2000 was farmland, but in 2010 and 2020, it was the forest ecosystem. The ecological service value of grassland and wetland was relatively small, while the ratio of the wetland ecological service value displayed a decreasing trend. In the future, it is necessary to establish a strict pretrial system for land use, so as to effectively protect the natural and semi-natural ecosystems and fulfill the growing ecological demands of residents.

Cold storage alters the fat-trehalose trade-off,decreases the flight ability,and maintains the high survival rate and flight speed of Osmia excavata(Hymenoptera:Megachilidae)

Osmia solitary bees are important pollinators of various crops worldwide.Refrigeration has been widely used to synchronize the emergence time of Osmia species from cocoons with the blooming time of different crops,but the fitness of Osmia after refrigeration remains unknown.Here,the effects of long-term refrigeration at 0℃on the vitality,flight ability,and metabolism of Osmia excavata,which is known as the"king of pollination"in China,were studied.The survival rate(>90%before 120 d),weight loss rate(<15%after 170 d),and mean flight speed of 0.excavata were not greatly affected after long-term refrigeration.The content of fats,which have antifreeze and energy storage properties,was not significantly altered in O.excavata before 130 d of refrigeration,which might explain why the survival rates and flight speed of O.excavata remained high after long-term refrigeration.However,the flight duration and distance decreased significantly(P<0.05),and both were positively correlated with the reduced trehalose levels in 0.excavata(r=[+0.69]-[+0.71];P<0.05).Overall,these findings indicate that the pollination potential of O.excavata for various crops with different flowering periods is high after long-term refrigeration;however,long-term refrigeration may decrease pollination efficiency.Our findings highlight new research directions that could improve the ecological service function of refrigerated O.excavata.