In order to examine the causes of degradation of Pinus sylvestris var. mongolica plantations on sandy land, the foliar concentrations of N, P, K and C were analyzed and compared between the field grown P. sylvestris v...In order to examine the causes of degradation of Pinus sylvestris var. mongolica plantations on sandy land, the foliar concentrations of N, P, K and C were analyzed and compared between the field grown P. sylvestris var. mongolica trees from two provenances （natural forests and plantations）. The results indicated that natural tree needles had lower N, P and C concentrations, and higher K concentrations than those of plantation tree needles. For plantation tree needles, ratios of N： P, P. K and N： K increased with tree age before 45 years old; but they were not clear for the natural tree needles. Compared with the conclusions reported on Pinus spp., we found that the foliar N and P concentrations were in the optimal range for both natural and plantation tree needles. This result suggested that N or P might not be the absolute limit factors in plant nutrient for P sylvestris var. mongolica on sandy land. However, foliar K concentrations in both natural and plantation tree needles were much lower than those reported on Pinus spp. （〉4.80 g kg-1）.The N： P ratio of natural needles was in the adequate ranges, but N： P ratio of plantation needles was out of the adequate ranges. These results indicated that there was a better balanced nutrition status in the natural forest than in the plantations. If only considering the foliar nutrient concentrations of P sylvestris var. mongolica from different provenances, it might be concluded that the degradation phenomenon of P. sylvestris var. mongolica plantations was not induced by nutrition deficiency of absolute nutrients of N and P, but might be induced by other mineral nutrients or by the effectiveness of N and P nutrients. The unbalanced nutrition status and relatively quick decomposition of needles in the plantations might also contribute to the degradation.展开更多
The runoff and runoff process of Eucalyptus plantations natural watershed were studied to provide guidance for scientific evaluation of water conservation capacities of Eucalyptus plantations,compared with the Pinus m...The runoff and runoff process of Eucalyptus plantations natural watershed were studied to provide guidance for scientific evaluation of water conservation capacities of Eucalyptus plantations,compared with the Pinus massoniana forest natural watershed. The runoff volumes of Eucalyptus plantations and P. massoniana forest natural watersheds were continuously monitored using the small watershed runoff monitoring method and the automatic data collection devices from August,2013 to December,2016,and effects of heavy rainfall and continuous rainfall on the runoff process were studied. Results showed that the annual runoff coefficient of Eucalyptus plantations natural watershed was 0. 050,and 55. 4% lower than P. massoniana forest（ 0. 112）,with the difference being significant（ P 〈 0. 01）. Total runoff duration,time of maximum runoff lagging behind rainfall peak,and runoff duration caused by a heavy rainfall process（ amounting to 147. 5 mm） between the two kinds of forest watersheds were significant different,those of Eucalyptus plantations were 35. 6 mm,0. 2 h and 13. 8 h,respectively,while those of P. massoniana forest were28. 5 mm,0. 7 h and 35. 5 h,respectively. Eucalyptus plantations natural watershed produced only 4-days runoff,and runoff depth amounted to3. 8 mm with a 7-days continuous precipitation process of rainfall with 125. 0 mm,while P. massoniana forest natural watershed produced continuously 13-days runoff,and the runoff depth was 10. 1 mm. In conclusion,water conservation capacity of Eucalyptus plantations is obviously lower than P. massoniana forest.展开更多
An investigation method with sample plots was used to study insect communities in four different growth phases of natural Populus euphratica forests, which are juvenile, middle aged, over-mature and degraded forests, ...An investigation method with sample plots was used to study insect communities in four different growth phases of natural Populus euphratica forests, which are juvenile, middle aged, over-mature and degraded forests, in Tarim, Xinjiang in July, 2005 and April, 2006. In our studies, 5,116 insect specimens, belonging to 12 orders, 61 families and 141 species, were collected. Lepidoptera and Coleoptera were the dominant orders. In middle-aged forests, species, individual numbers and diversity indices of insect com-munities were higher than those in other woodlands. The species richness and diversity indices were lowest in degraded forests be-cause of extremely scarce vegetation.展开更多
Natural resources represent the base of our living and the entire economic activity.Their depletion is a major challenge for the economic development of both developed and developing economies.Their effi-cient use is ...Natural resources represent the base of our living and the entire economic activity.Their depletion is a major challenge for the economic development of both developed and developing economies.Their effi-cient use is an indispensable requirement and must be the aim of the public policies designed by the authorities worldwide.In this research,we have investigated the impact of the natural resources rent on the economic growth in some major wealthy economies of the world(P5+1 countries namely:US,UK,France,China,Russia,and Germany).We have applied a quantile-on-quantile regression to analyse this impact on different quantiles and a cross-sectional autoregressive distributed lag(CS-ARDL)approach for the panel of these six countries.The Dumitrescu-Hurlin panel causality test was also used to check the causality between natural resource rents and economic growth in these countries.Results show a negative relationship between natural resources rent and economic growth for the panel but a different impact on quantiles in each country.Only for China and the US,a positive effect can be noticed for both lower and higher quantiles of natural resources and economic growth.The Dumitrescu-Hurlin causality test shows that natural resources can predict economic growth only in China,the U.S.,and the panel.In contrast,no causality was found for the other four countries included in the panel.We suggest that nations invest in wind and solar projects,use biofuels and nuclear energy,introduce a temporary profit tax to protect consumers from escalating energy prices,and increase energy efficiency in buildings and industry.Businesses would benefit from a regulatory framework that is uniform and exhaustive,as well as easier to traverse and more receptive to innovation and creativity.Public-private partnership investments in innovation,innovation incentives,and environmental sector opportunities may foster long-term economic growth。展开更多
基金The research was supported by Innovation Research Project of Chinese Academy of Sciences (KZCX3-SW-418), and the 100 Young Researcher Project of Chinese Academy of Sciences.
文摘In order to examine the causes of degradation of Pinus sylvestris var. mongolica plantations on sandy land, the foliar concentrations of N, P, K and C were analyzed and compared between the field grown P. sylvestris var. mongolica trees from two provenances （natural forests and plantations）. The results indicated that natural tree needles had lower N, P and C concentrations, and higher K concentrations than those of plantation tree needles. For plantation tree needles, ratios of N： P, P. K and N： K increased with tree age before 45 years old; but they were not clear for the natural tree needles. Compared with the conclusions reported on Pinus spp., we found that the foliar N and P concentrations were in the optimal range for both natural and plantation tree needles. This result suggested that N or P might not be the absolute limit factors in plant nutrient for P sylvestris var. mongolica on sandy land. However, foliar K concentrations in both natural and plantation tree needles were much lower than those reported on Pinus spp. （〉4.80 g kg-1）.The N： P ratio of natural needles was in the adequate ranges, but N： P ratio of plantation needles was out of the adequate ranges. These results indicated that there was a better balanced nutrition status in the natural forest than in the plantations. If only considering the foliar nutrient concentrations of P sylvestris var. mongolica from different provenances, it might be concluded that the degradation phenomenon of P. sylvestris var. mongolica plantations was not induced by nutrition deficiency of absolute nutrients of N and P, but might be induced by other mineral nutrients or by the effectiveness of N and P nutrients. The unbalanced nutrition status and relatively quick decomposition of needles in the plantations might also contribute to the degradation.
基金Supported by Special Project for Scientific Research of Public Welfare Industry of Ministry of Water Resources(201301044)
文摘The runoff and runoff process of Eucalyptus plantations natural watershed were studied to provide guidance for scientific evaluation of water conservation capacities of Eucalyptus plantations,compared with the Pinus massoniana forest natural watershed. The runoff volumes of Eucalyptus plantations and P. massoniana forest natural watersheds were continuously monitored using the small watershed runoff monitoring method and the automatic data collection devices from August,2013 to December,2016,and effects of heavy rainfall and continuous rainfall on the runoff process were studied. Results showed that the annual runoff coefficient of Eucalyptus plantations natural watershed was 0. 050,and 55. 4% lower than P. massoniana forest（ 0. 112）,with the difference being significant（ P 〈 0. 01）. Total runoff duration,time of maximum runoff lagging behind rainfall peak,and runoff duration caused by a heavy rainfall process（ amounting to 147. 5 mm） between the two kinds of forest watersheds were significant different,those of Eucalyptus plantations were 35. 6 mm,0. 2 h and 13. 8 h,respectively,while those of P. massoniana forest were28. 5 mm,0. 7 h and 35. 5 h,respectively. Eucalyptus plantations natural watershed produced only 4-days runoff,and runoff depth amounted to3. 8 mm with a 7-days continuous precipitation process of rainfall with 125. 0 mm,while P. massoniana forest natural watershed produced continuously 13-days runoff,and the runoff depth was 10. 1 mm. In conclusion,water conservation capacity of Eucalyptus plantations is obviously lower than P. massoniana forest.
文摘An investigation method with sample plots was used to study insect communities in four different growth phases of natural Populus euphratica forests, which are juvenile, middle aged, over-mature and degraded forests, in Tarim, Xinjiang in July, 2005 and April, 2006. In our studies, 5,116 insect specimens, belonging to 12 orders, 61 families and 141 species, were collected. Lepidoptera and Coleoptera were the dominant orders. In middle-aged forests, species, individual numbers and diversity indices of insect com-munities were higher than those in other woodlands. The species richness and diversity indices were lowest in degraded forests be-cause of extremely scarce vegetation.
文摘Natural resources represent the base of our living and the entire economic activity.Their depletion is a major challenge for the economic development of both developed and developing economies.Their effi-cient use is an indispensable requirement and must be the aim of the public policies designed by the authorities worldwide.In this research,we have investigated the impact of the natural resources rent on the economic growth in some major wealthy economies of the world(P5+1 countries namely:US,UK,France,China,Russia,and Germany).We have applied a quantile-on-quantile regression to analyse this impact on different quantiles and a cross-sectional autoregressive distributed lag(CS-ARDL)approach for the panel of these six countries.The Dumitrescu-Hurlin panel causality test was also used to check the causality between natural resource rents and economic growth in these countries.Results show a negative relationship between natural resources rent and economic growth for the panel but a different impact on quantiles in each country.Only for China and the US,a positive effect can be noticed for both lower and higher quantiles of natural resources and economic growth.The Dumitrescu-Hurlin causality test shows that natural resources can predict economic growth only in China,the U.S.,and the panel.In contrast,no causality was found for the other four countries included in the panel.We suggest that nations invest in wind and solar projects,use biofuels and nuclear energy,introduce a temporary profit tax to protect consumers from escalating energy prices,and increase energy efficiency in buildings and industry.Businesses would benefit from a regulatory framework that is uniform and exhaustive,as well as easier to traverse and more receptive to innovation and creativity.Public-private partnership investments in innovation,innovation incentives,and environmental sector opportunities may foster long-term economic growth。
