Effect Of Tending On Whole Tree Water Consumption And Stand Growth Of Beijing Platycladus Orientalis Plantation

The Platycladus orientalis plantation, is an important afforestation species in mountainous areas of Beijing, which covers an area of59816.8hm2, count for20%of the total non-commercial forests, and improving quality of the stand is the key stone of ecological construction in Beijing. The scientific forest tending can improve stand health conditions, improve the quality of trees, enhance forest protection to better play the economic, ecological and social benefits of forests though forests cultivation. Exploring the impact of forest tending for water consumption and growth of the Platycladus orientalis plantation can provide a reference value for tending technology decision-making, so that orientalis give a better play to the comprehensive benefits.In this study, on the basis of previous research, selecting Platycladus orientalis plantation plots of Long mountain and Hanbao mountain in Chang ping District (2004for cultivation), to study the effect of tending on whole tree water consumption and stand growth of beijing oriental arborvitae. The results as follows:1. Platycladus orientalis in Chang ping Long mountain include four treatments, L1(weak tending stand), L2(control stand), L3(moderate tending stand) and L4(high intensity tending stand), diurnal variation of slap flow characterized as follows:In certain site conditions, the more intensive tending, the earlier the slap flow start time. When it is sunny, the sap flow of L4, L3and L1start up around30,20and10minutes earlier than L2;The time when stem sap flow reach the peak is around11:00,11:20and11:50, which is130,110and80minutes earlier than L2separately; L3has the biggest peak values and average daily flow rates, about0.00971cm/s and0.00251cm/s, while peak values is about1.10times of L4,1.41times of L1and1.65times of L2, peak values is about1.03times of L4,1.27times of L1and1.42times of L2. When it is cloudy, the sap flow of L4start time is30minutes earlier than L2and L3,and20minutes earlier to reach the peak; L3has the biggest peak values and average daily flow rates as well, about0.00710cm/s and0.00166cm/s, while peak values is about1.03times of L4,1.69times of L1and1.46times of L2, peak values is about i.07times of L4,1.61times of L1and1.37times of L2.2. The density relationship of Platycladus orientalis in Chang ping Han bao mountain, h1(control),h4(weak),h3(weak)and h2(weak degree), Start time of sap flow in sunny days is basically the same as in cloudy days, when it rains, sap flow of tending stand starts earlier than the control stand; sap flow peak and the average daily flow rate increase while stand density decreases. When it is sunny, the stands with h2have the biggest peak values of sap flow and average daily flow rates,0.00683cm/s and0.00190cm/s separately, h3and h4follows by, they are1.60and1.31times,1.45and1.22times and1.39and1.14times of h1. When it is cloudy, the control stand has the biggest peak values of sap flow and average daily flow rates, which is0.00211cm/s and0.00049cm/s, they are1.64and1.73times of h2,1.40and1.53times of h3,1.48and1.66times of h4. In raining days, the sap flow of h2-h4starts up at05:20, it is30minutes earlier than hi, and reach peak at7:10; h2has the biggest peak values of sap flow and average daily flow rates, which is0.0.0167cm/s and0.00049cm/s, h4and h3follows by, separately they are1.11and1.86times,1.05and1.71times and1.01and1.59times of h1.3. Correlation between stem sap flow rate and meteorological factors vary with the tending intensity, the correlation of moderate tending stands is closer than the control stands. The moderate tending stands have the highest correlation with the air water vapor pressure deficit and air temperature; the high intensity tending stands have the highest correlation with the relative humidity of the air; while the weak tending stands have the highest correlation with the effective solar radiation.4. Tending can significantly promote Platycladus orientalis stand average diameter and diameter at breast height of Long mountain plots, but no obvious influences on tree height growth, single timber product and accumulation of per unit area. After seven years from tending, Average DBH of L4,L3and LI have increased2.51cm,2.08cm and1.78cm, which is52%.26%and8%higher than L2; The average crown width have increased0.92m、0.97m and0.80m, which is31%、39%and14%more than L2.Tending can significantly promote Platycladus orientalis average diameter, diameter at breast height and single timber product of Han bao mountain plots, but no obvious influences on tree height growth and accumulation of per unit area. After seven years from tending, Average DBH of h2,h3and h4have increased2.04cm、1.75cm and1.79cm, which is49%.28%and31%higher than h1; average diameter of h2,h3and h4have increased0.58m.0.57m and0.41m, which is132%.128%and64%higher than h1; single timber product of h2,h3and h4have increased0.0015m3.0.0019m3and0.0013m3, which is72.7、36.4%and18.2%higher than h1.5. In summary, the density of Platycladus orientalis stand in Beijing after30years’afforestation should be controlled in the2000strains/hm2～3000strains/hm2; orientalis stand with a density of3400strains/hm2～4600strains/hm2of20to30years old need a rearing cycle of5to6years.