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G erber et al, studying 41 chronic anterior cruciate ligament (ACL) deficient knees, reported a 2.2% decrease in thigh circumference measurements and a 10% quadriceps femoris and 4% hamstring (combined 8%) decrease in muscle cross-sectional area by computed tomography (1 1). Kariya et al, studying 21 chronic ACMeficient knees, reported an 11.2% decrease in quadriceps muscle cross-sectional area by magnetic resonance imaging (MRI) (19). Kannus et al, studying 21 chronic ACMeficient knees without surgery, reported an 88% hamstring-tquadriceps ratio of the involved leg compared with a 78% hamstring-tquadriceps ratio in the uninvolved leg (3,l i',l8). Other authors have reported residual weakness of the quadriceps after various anterior cruciate ligament reconstructions and rehabilitation (12,20,23,25, 26,28,31,33).Variables including preoperative quadriceps weakness and atrophy, timing of surgery, postoperative laxity, morbidity of graft harvest sites, use of tourniquet, and postoperative immobilization and arthrotomy vs. arthroscopically assisted surgery have been implicated to explain postoperative failure to regain normal quadriceps size and strength (2,12,25,32,33

China is several decades into large-scale afforestation programs to help address significant ecological and environmental degradation, with further afforestation planned for the future. However, the biophysical impact of afforestation on local surface temperature remains poorly understood, particularly in midlatitude regions where the importance of the radiative effect driven by albedo and the nonradiative effect driven by energy partitioning is uncertain. To examine this issue, we investigated the local impact of afforestation by comparing adjacent forest and open land pixels using satellite observations between 2001 and 2012. We attributed local surface temperature change between adjacent forest and open land to radiative and nonradiative effects over China based on the Intrinsic Biophysical Mechanism (IBM) method. Our results reveal that forest causes warming of 0.23°C (±0.21°C) through the radiative effect and cooling of −0.74°C (±0.50°C) through the nonradiative effect on local surface temperature compared with open land. The nonradiative effect explains about 79% (±16%) of local surface temperature change between adjacent forest and open land. The contribution of the nonradiative effect varies with forest and open land types. The largest cooling is achieved by replacing grasslands or rain-fed croplands with evergreen tree types. Conversely, converting irrigated croplands to deciduous broadleaf forest leads to warming. This provides new guidance on afforestation strategies, including how these should be informed by local conditions to avoid amplifying climate-related warming.

Abstract. To resolve a series of ecological and environmental problems over the Loess Plateau, the “Grain for Green Program” (GFGP) was initiated at the end of 1990s. Following the conversion of croplands and bare land on hillslopes to forests, the Loess Plateau has displayed a significant greening trend, which has resulted in soil erosion being reduced. However, the GFGP has also affected the hydrology of the Loess Plateau, which has raised questions regarding whether the GFGP should be continued in the future. We investigated the impact of revegetation on the hydrology of the Loess Plateau using relatively high-resolution simulations and multiple realizations with the Weather Research and Forecasting (WRF) model. Results suggest that revegetation since the launch of the GFGP has reduced runoff and soil moisture due to enhanced evapotranspiration. Further revegetation associated with the GFGP policy is likely to further increase evapotranspiration, and thereby reduce runoff and soil moisture. The increase in evapotranspiration is associated with biophysical changes, including deeper roots that deplete deep soil moisture stores. However, despite the increase in evapotranspiration, our results show no impact on rainfall. Our study cautions against further revegetation over the Loess Plateau given the reduction in water available for agriculture and human settlements and the lack of any significant compensation from rainfall.