Effect Of Thinning And Mulching Application On Photosynthesis And Water-use Efficiency In Ligustrum Lucidum Ait

In this study, we discussed the influences on the short-term effects of photosyntheticcharacteristics and water use efficiency of the thinning and mulching in the6-year-old Ligustrumlucidum Ait. plantation. The study was in order to find a reasonable operating measure to increasenet photosynthetic rate and water-use efficiency, to provide a scientific basis for the constructionand management of resource-saving urban greenland. The main results were as follows:(1) Overall, mulching increased the soil water content and raised the soil temperature. Andthe straw mulching influenced on the regulation of soil heat and water most significantly.Soiltemperature increased after thinning, and straw mulching played an important role in adjustingthe temperature and humidity.Litter mulching and gravel mulching is less than the strawmulching in adjusting the temperature and humidity.(2)Thinning and mulching changed the forest canopy microclimate.Mulching significantlyreduced the air temperature, and increased the air relative humidity. The effect of the strawmulching on Ta and RH was obvious. Thinning increased photosynthetic active radiation, whichincreased air temperature, reduced air relative humidity.(3) In peak of growing season,the diurnal variation of Pn of Ligustrum lucidum Aitundershowed a typical double peak curve. The photosynthetic characteristics under different mulchingtreatment were significant differences (P <0.05). compared with CK, straw mulching and littermulching added the daily mean value of Pn, and gravel mulching reduced the daily mean valueof Pn. Plants’ maximum Pn reached earlier after thinning, moderate thinning and high thinningsignificantly increased the Pn of the daily average (P <0.05). The Pn day average was the largestin moderate thinning and straw mulching.(4) In general, mulching improved water use efficiency of plant leaves: straw mulching>gravel mulching> CK> litter mulching, the significant difference exsited between the groups (P<0.05). Thinning with straw mulching and thinning with gravel mulching increased water useefficiency in Ligustrum lucidum Ait.In order to improve urban green photosynthetic rate and water use efficiency, the densityregulation and biological cover should be implemented.