First-year growth of planted Douglas-fir and white fir seedling under different shelterwood regimes in California
First-year growth of planted Douglas-fir and white fir seedling under different shelterwood regimes in California
复制标题
加利福尼亚州不同防护林制度下种植的花旗松和白冷杉幼苗的第一年生长情况
DOI：
10.1016/0378-1127(83)90031-2
复制
发表时间：
1983
影响因子：
3.7
通讯作者：
J. Helms
中科院分区：
文献类型：
--
作者：
J. Dunlap;J. Helms
1979年在加利福尼亚州中部的塞拉山脉采伐了一片17公顷的林地，提供了三片防护林，剩余面积分别为10、15和20平方米/公顷。以相邻的75m2/hm2未砍伐林为对照。在1980年夏天，对苗木的表现和五个微环境特征进行了评估。不同防护林的最高气温相似；最低气温相差约3°C。所有防护林的日潜在蒸发量相似，从6月到7月增加了一倍，并在整个9月保持不变。对照的蒸发量是防护林的一半。次生土壤温度在8月份达到最高值，密度最低的防护林为24℃，对照为16℃。在5月份，所有处理的地下土壤水分为35%，但在9月份，密度最小的防护林和对照的地下土壤水分分别为18%和12%。6月日入射光在密度最小和密度最大的防护林中分别为最大值的76%~54%，在对照林中为最大值的12%，所有处理的道格拉斯冷杉存活率均在93%以上。白冷杉的存活率随覆被密度的增加在63%~85%之间，差异不显著。白冷杉迅速死亡的时期出现在夏季后期，随着郁闭度的增加。在密度最低的防护林下，两种树种的树高生长量分别为2.3 cm和3.1 cm，但处理间差异显著，处理10和处理15的树干直径生长量为1.3 mm左右，显著大于处理20和对照的0.3 mm生长量。针阔混交林地上部：根比和生物量随林分减少呈增加趋势。在白冷杉中，地上部与根部之比则相反，但生物量在各防护林中相似。未采伐林分苗木生长最差，水分胁迫为-19bar(-1.9 Mpa)，白冷杉为-22bar(-2.2 Mpa)。结果表明，10m2/ha的防护林为容器育苗提供了1年成功存活和生长的条件，但15m2/ha的密度更适合裸根白冷杉。在高达20m2/hm2的防护林下，新梢生长的启动似乎没有延迟。
A 17-ha area in the central California Sierra was harvested in 1979 to provide three shelterwoods with residual basal areas of 10, 15 and 20 m2/ha. An adjacent uncut stand of 75 m2/ha was used as a control. During the summer of 1980, seedling performance was assessed along with five microenvironmental characteristics. Maximum air temperature was similar among shelterwoods; minimum air temperature varied by about 3°C. Daily potential evaporation in all shelterwoods was similar and doubledfrom June to July and remained constant through September. Evaporation in the control was half of the shelterwoods. Subsurface soil temperature reached a maximum in August of 24°C in the least-dense shelterwood and 16°C in the control. Subsurface soil moisture was 35% for all treatments in May, but in September was 18% in the least-dense shelterwood and 12% in the control. Daily incident light in June ranged from 76% to 54% of maximum in the least-dense and most-dense shelterwood respectively, and 12% of maximum in the control.Survival of Douglas-fir was greater than 93% in all treatments. However, survival of white fir ranged from 63% to 85% as the overstory density increased; these differences were not significant. The period of rapid white fir mortality occurred later in the summer with increasing canopy cover. Height growth of both species was about 2.3 cm in the control to 3.1 cm under the least-dense shelterwood; however, treatment differences were significant only for white fir, Stem diameter growth of about 1.3 mm in treatments 10 and 15 was significantly greater than the growth of 0.3 mm in treatments 20 and the control. In Douglas-fir shoot: root ratios and biomass tended to increase with decreasing shelterwood. In white fir, the reverse trend was observed for shoot:root ratio but biomass production was similar in each shelterwood. Seedling sshowed the least overall growth in the uncut stand where plant moisture stress reached -19 bar (-1.9 MPa) in Douglas-fir and -22 bar (-2.2 MPa) in white fir.Results indicate that a 10 m2/ha shelterwood provides conditions for successful 1st-year survival and growth of container-grown Douglas-fir, but a 15 m2/ha density is preferable for bare-root white fir. Shoot growth initiation does not seem to be delayed under shelterwoods of up to 20 m2/ha.