Tourism, transport energy consumption, and the carbon dioxide emission nexus for the USA: Evidence from wavelet coherence and spectral causality approaches

The aim of this study is to analyze the dynamic relationship between tourism, transport energy consumption, and carbon dioxide emissions in the United States from the 1st quarter of 1995 to the 4th quarter of 2019. To this end, we utilize the autoregressive distributed lag (ARDL), the Wavelet Coherence Approach (WCA), and the Breitung-Candelon spectral granger causality approaches. The empirical outcomes confirm that the variables included in the model exhibit cointegration. The estimations of the wavelet coherence approach confirm that tourism stimulates transport energy consumption, whereas both tourism and energy consumption bolster carbon emissions in the United States. The outcomes for the Breitung-Candelon spectral granger causality approach suggest that our variables exhibit causal associations at various frequencies. These are findings are also robust to alternative econometrics specifications. These empirical outcomes underscore the fact that tourism propel both transport energy consumption and carbon emissions. Our study helps policymakers in regards to revisiting the role of tourism and transport energy consumption concerning emissions in order to cope with environmental challenges in the United States.</p

DataSheet_1_Photosynthetic and yield responses of rotating planting strips and reducing nitrogen fertilizer application in maize–peanut intercropping in dry farming areas.docx

Improving cropping systems together with suitable agronomic management practices can maintain dry farming productivity and reduce water competition with low N inputs. The objective of the study was to determine the photosynthetic and yield responses of maize and peanut under six treatments: sole maize, sole peanut, maize–peanut intercropping, maize–peanut rotation–intercropping, 20% and 40% N reductions for maize in the maize–peanut rotation–intercropping. Maize–peanut intercropping had no land-use advantage. Intercropped peanut is limited in carboxylation rates and electron transport rate (ETR), leading to a decrease in hundred-grain weight (HGW) and an increase in blighted pods number per plant (NBP). Intercropped peanut adapts to light stress by decreasing light saturation point (Isat) and light compensation point (Icomp) and increasing the electron transport efficiency. Intercropped maize showed an increase in maximum photosynthetic rate (Pnmax) and Icomp due to a combination of improved intercellular CO2 concentration, carboxylation rates, PSII photochemical quantum efficiency, and ETR. Compare to maize–peanut intercropping, maize–peanut rotation–intercropping alleviated the continuous crop barriers of intercropped border row peanut by improving carboxylation rates, electron transport efficiency and decreasing Isat, thereby increasing its HGW and NBP. More importantly, the land equivalent ratio of maize–peanut rotation–intercropping in the second and third planting years were 1.05 and 1.07, respectively, showing obvious land use advantages. A 20% N reduction for maize in maize–peanut rotation–intercropping does not affect photosynthetic character and yield for intercropped crops. However, a 40% N reduction decreased significantly the carboxylation rates, ETR, Icomp and Pnmax of intercropped maize, thereby reducing in a 14.83% HGW and 5.75% lower grain number per spike, and making land-use efficiency negative.</p