Formation mechanisms and remediation techniques for low-efficiency artificial shelter forests on the Chinese Loess Plateau

The construction of artificial shelter forests(ASFs)has resulted in substantial ecological,economic,and societal benefits to the Chinese Loess Plateau(CLP).However,the health and benefits of ASFs are being increasingly threatened by the formation of low-efficiency artificial shelter forests(LEASFs).In this study,LEASFs are systematically analyzed in terms of their status,formation mechanisms,and developmental obstacles.The key restoration techniques and schemes were summarized to improve the quality and efficiency of LEASFs.LEASFs are formed by relatively complex mechanisms,but they arise mainly due to poor habitat conditions,improper tree species selections,mismatch between stands and habitat,extensive forest management measures,and human interferences.The restoration and improvement of LEASFs are hindered by water deficits,mismatch between stands and habitat,single management purpose,and low efficiency.LEASFs are becoming more complex due to their wide range,the challenges associated with their restoration,and insufficient technological measures for their restoration.The key techniques of the quality and efficiency improvement of LEASFs include basic forest tending methods,near-natural restoration,multifunction-oriented improvement,and systematic restoration.An understanding on the formation mechanisms of LEASFs and a scientific approach toward their restoration are urgently needed and critical for the ecological protection and high-quality development of LEASFs on the CLP.Based on these analyses,we recommend strengthening the monitoring and supervision of LEASFs,considering the bearing capacity of regional water resources,implementing multiple restoration techniques,promoting multifunction-oriented ecological development,and exploring new management concepts to achieve the sustainable development of ASFs on the CLP.

Precipitation Controls on Carbon Sinks in an Artificial Green Space in the Taklimakan Desert

Control of desertification can not only ameliorate the natural environment of arid regions but also convert desertified land into significant terrestrial carbon sinks,thereby bolstering the carbon sequestration capacity of arid ecosystems.However,longstanding neglect of the potential carbon sink benefits of desertification management,and its relationship with environmental factors,has limited the exploration of carbon sequestration potential.Based on CO_(2) flux and environmental factors of artificial protective forest in the Taklamakan Desert from 2018 to 2019,we found that the carbon storage capacity of the desert ecosystem increased approximately 140-fold after the establishment of an artificial shelter forest in the desert,due to plant photosynthesis.Precipitation levels less than 2 mm had no impact on carbon exchange in the artificial shelter forest,whereas a precipitation level of approximately 4 mm stimulated a decrease in the vapor pressure deficit over a short period of about three days,promoting photosynthesis and enhancing the carbon absorption of the artificial shelter forest.Precipitation events greater than 8 mm stimulated soil respiration to release CO_(2) and promoted plant photosynthesis.In the dynamic equilibrium where precipitation stimulates both soil respiration and photosynthesis,there is a significant threshold value of soil moisture at 5 cm(0.12 m^(3) m^(-3)),which can serve as a good indicator of the strength of the stimulatory effect of precipitation on both.These results provide important data support for quantifying the contribution of artificial afforestation to carbon sequestration in arid areas,and provide guidance for the development and implementation of artificial forest management measures.

Nest-cavity characteristics of the Great Spotted Woodpecker Dendrocopos major in shelter plantations of west Inner Mongolia

The Great Spotted Woodpecker Dendrocopos major （L.）, one of the natural predators of Anoplophora glabripennis （Motsch.） （Coleoptera： Cerambycidae）, is resident to Wulate Qianqi County of the Inner Mongolia and widely found in shelter plantations. In August 2005 and 2006, 174 and 153 nest-cavities of Great Spotted Woodpeckers were found respectively in Wulate Qianqi County and 22 breeding nest-cavities were investigated in 2007. The results showed that mostly willow species were selected for nesting by the Great Spotted Woodpecker, but mature poplar trees also could be chosen. Nest cavities were often found with a protuberance above the cavity entrance or with a downward sloping gradient, or both. The selection of the height of the nest-cavity height was not significant. The vertical diameter of the nest-cavity entrance （VDE） and the horizontal diameter of the nest-cavity entrance （HDE） ranged from 5.0 to 5.8 cm. The results also indicated that the compass orientation of more than 60% of nest-cavities were towards the north, northeast and east. This study suggests a convergence of some nest-cavity characteristics of the Great Spotted Woodpecker in shelter plantations and will help us to make artificial nest for conserving the woodpecker and, as well, use the bird for controlling pests.