[Objective] This study aimed to explore the impact of climate change on wheat cropping by using province-specific historical data during 1996-2007. [Method] We established a panel data econometric model with lagged wh...[Objective] This study aimed to explore the impact of climate change on wheat cropping by using province-specific historical data during 1996-2007. [Method] We established a panel data econometric model with lagged wheat cropping area and province-specific fixed-effects model to control the unobserved factors. [Result] The results showed that the temperature positively affects wheat cropping area, while precipitation does not have such impact. [Conclusion] The study provided empirical evidence for analysis of the determinants of wheat cropping area in China.展开更多
Timberland investment opportunities in Colombia are expected to increase as a result of the peace agreement recently signed between the Colombian government and the Revolutionary Armed Forces of Colombia. This new soc...Timberland investment opportunities in Colombia are expected to increase as a result of the peace agreement recently signed between the Colombian government and the Revolutionary Armed Forces of Colombia. This new socio-political environment may facilitate the expansion of commercial forest plantations on a wider range of site conditions that are currently considered in existing biometric tools. Data from 1119 temporary plots of unthinned, unmanaged, and genetically unimproved Pinus patula plantations in the Antioquia region were combined with a large set of biophysical attributes to identify spatial variation in yield. A wide array of biophysical covariates was explored to characterize the most favorable environmental conditions for the species, and to identify potential explanatory variables to be included in forest yield models. The mathematical form of the model is the von Bertalanffy-Chapman-Richards type, with parameters: asymptote, intrinsic growth rate and allometric constant. The parameters were expressed as linear functions of soil pH, terrain slope, the mean annual temperature to mean annual precipitation ratio, and stand density. The statistical contribution of selected covariates was evaluated using the likelihood ratio test. The model was validated using an independent set of 133 observations. The spatial representation of the model depicts the timber production potential and allows for the identification of the most suitable geographical areas to establish Pinus patula plantations in Antioquia, Colombia. The estimated yield model provides a reliable baseline for timber production, and insight into timberland investments in Colombia.展开更多
China has launched six Priority Forestry Programs (PFPs) since 1998, i.e. the Natural Forest Protection Program, the Cropland Conversion to Forest and Grassland Program, Sandification Control Program for the Vicinity ...China has launched six Priority Forestry Programs (PFPs) since 1998, i.e. the Natural Forest Protection Program, the Cropland Conversion to Forest and Grassland Program, Sandification Control Program for the Vicinity of Beijing & Tianjin , Wildlife Conservation and Nature Reserve Development Program, Forest Industrial Base Development Program and Shelterbelt Development Programs for regions such as Three North and the Yangtze River Catchments. The Government of China has made different policies for these PFPs, such as subsidies, low-interest loans and revenue offsets. Using a fixed-effect model and panel data from 2 353 households in 9 counties of Sichuan, Hebei, Shaanxi, and Jiangxi provinces, this paper studies effects of PFPs on farmers’ incomes. The empirical results indicate that the effects of PFPs on farmers’ incomes are mixed. Overall, the impact of Conversion of Cropland to Forestland and Grassland Program is significantly positive, whereas that of the Natural Forest Protection Program and the Sandification Control Program around Beijing & Tianjin is negative. To a lesser extent, the Shelterbelt Development Programs have a positive impact. In the meantime, different effects of PFPs on farmers’ incomes are also mixed for different provinces and different households are also mixed.展开更多
基金Supported by the National Natural Science Foundation of China (41101165)~~
文摘[Objective] This study aimed to explore the impact of climate change on wheat cropping by using province-specific historical data during 1996-2007. [Method] We established a panel data econometric model with lagged wheat cropping area and province-specific fixed-effects model to control the unobserved factors. [Result] The results showed that the temperature positively affects wheat cropping area, while precipitation does not have such impact. [Conclusion] The study provided empirical evidence for analysis of the determinants of wheat cropping area in China.
文摘Timberland investment opportunities in Colombia are expected to increase as a result of the peace agreement recently signed between the Colombian government and the Revolutionary Armed Forces of Colombia. This new socio-political environment may facilitate the expansion of commercial forest plantations on a wider range of site conditions that are currently considered in existing biometric tools. Data from 1119 temporary plots of unthinned, unmanaged, and genetically unimproved Pinus patula plantations in the Antioquia region were combined with a large set of biophysical attributes to identify spatial variation in yield. A wide array of biophysical covariates was explored to characterize the most favorable environmental conditions for the species, and to identify potential explanatory variables to be included in forest yield models. The mathematical form of the model is the von Bertalanffy-Chapman-Richards type, with parameters: asymptote, intrinsic growth rate and allometric constant. The parameters were expressed as linear functions of soil pH, terrain slope, the mean annual temperature to mean annual precipitation ratio, and stand density. The statistical contribution of selected covariates was evaluated using the likelihood ratio test. The model was validated using an independent set of 133 observations. The spatial representation of the model depicts the timber production potential and allows for the identification of the most suitable geographical areas to establish Pinus patula plantations in Antioquia, Colombia. The estimated yield model provides a reliable baseline for timber production, and insight into timberland investments in Colombia.
文摘China has launched six Priority Forestry Programs (PFPs) since 1998, i.e. the Natural Forest Protection Program, the Cropland Conversion to Forest and Grassland Program, Sandification Control Program for the Vicinity of Beijing & Tianjin , Wildlife Conservation and Nature Reserve Development Program, Forest Industrial Base Development Program and Shelterbelt Development Programs for regions such as Three North and the Yangtze River Catchments. The Government of China has made different policies for these PFPs, such as subsidies, low-interest loans and revenue offsets. Using a fixed-effect model and panel data from 2 353 households in 9 counties of Sichuan, Hebei, Shaanxi, and Jiangxi provinces, this paper studies effects of PFPs on farmers’ incomes. The empirical results indicate that the effects of PFPs on farmers’ incomes are mixed. Overall, the impact of Conversion of Cropland to Forestland and Grassland Program is significantly positive, whereas that of the Natural Forest Protection Program and the Sandification Control Program around Beijing & Tianjin is negative. To a lesser extent, the Shelterbelt Development Programs have a positive impact. In the meantime, different effects of PFPs on farmers’ incomes are also mixed for different provinces and different households are also mixed.
