Postfire Regeneration in <Emphasis Type="Italic">Pinus pinea</Emphasis> L. and <Emphasis Type="Italic">Pinus pinaster</Emphasis> Aiton in Andalucia (Spain)

The objective of this study was to examine postfire regeneration of tree, shrub, and dwarf shrub species, in relation to levels of damage in four planted pine forests (Pinus pinea, Pinus pinaster) in Andalusia. A prefire vegetation map was used for detailing species composition, vertical structure, and density and another for detailing the extent and intensity of fire damage. Between 3 and 7 years after the fires, an inventory was made of the vegetation in each area, using the step-point method. The information thus obtained was used to determine the amount of cover in the dwarf/shrub and tree layers, the frequency of species in each of the layers, floristic richness, and diversity (Shannon index). The botanical composition of the dwarf and shrub layer was analyzed using TWINSPAN. Variables were poorly correlated with level of fire damage, which suggests that the forests in this study followed the autosuccession model. Because of the artificial origin or seminatural condition, regeneration of the dominant tree species is poor, and it seems unlikely that forests will recover to their prefire state. Therefore action is recommended to restore these ecosystems.     

Air Pollution Effects on Annual Ring Widths of Forest Trees in Mountainous Land of Izmir (Turkey)

Annual ring widths of forest trees are affected from different ecologicalfactors (e.g. climate, soil, etc.) and also from air pollution. In the areas with intensive air pollution annual ring width reductions are observed. For this reason, some methods which detect the annual ring widths, in other words, the increase or decrease in diameter increments, are used to examine air pollution. Industrial establishments found in the northern part of Izmir city (Aliaga region) affect air quality of this area negatively. In this investigation, annual ring widths of 13 Pinus brutia Ten. (Calabrian pine) and 20 Pinus nigra Arnold. (Austrian pine) from 4 mountains (Karabelen, Manisa, Kemalpasa, and Yamanlar) with different altitudes and exposures around Izmir city were detected and the effects of air pollution on these trees were determined. Intensive effects of air pollution have started in 1985, for that reason, annual ring widths were examined through a reference period before this year and a study period (1985–1998) after this year and results are statistically evaluated. Annual ring widths of tree samples in the northern exposure were affected from air pollution, and some reductions were observed. These reductions increased when there is a long drought period.     

Ecophysiological Responses of Larix sibiricaLedeb. and Pinus sibiricaDu Tour Undergrowth to Climate Change

The effects of probable climate change—an increase in atmospheric CO₂(by two times), air temperature, precipitation—on CO₂exchange and temperature dependence of net photosynthesis in the larch and Siberian stone pine undergrowth formed in the light larch forests of West Siberia were studied in chambers with an artificial climate. The change of the aforementioned ecological factors caused an increase in the temperature optima of photosynthesis and the range of optimum temperatures (in the case of Siberian stone pine, to a slightly greater degree). Therefore, the ranges of both species may broaden, and the Siberian stone pine can expand to the north, displacing larch tree stands.     

油松过氧化物酶季节变化动态

采用聚丙烯酰胺凝胶电泳技术,对华北地区14个油松种源的过氧化物酶(POD)季节变化动态进行了分析.电泳共分离出8条谱带,其中一条为油松的特征谱带.其余7条在不同生长季节均有较明显的变化,且不同种源间POD酶谱变化具有一定的差异,表明油松植物过氧化物酶具有季节性生长阶段的特异性和种源特异性.     

鸡粪热裂解对重金属Mn、Cu、Zn和Cr生物有效性的影响

畜禽粪便直接农用引起的重金属污染是社会普遍关注的问题,探索如何有效降低畜禽粪便重金属生物有效性的技术是急需解决的难题.本文通过分析鸡粪(CM)裂解前后Mn、Cu、Zn和Cr等4种重金属形态分布变化,并采用林地大型盆栽试验研究添加CM和鸡粪炭(CMB)处理对湿地松地上部分重金属吸收状况的影响.结果表明,与CM直接还田相比,添加CMB(400℃)处理降低Mn、Cu和Zn在湿地松地上部分的吸收量和富集系数,而处理之间植株Cr元素的吸收量和富集系数差异不显著. Tessier连续提取结果表明, Mn、Cu和Zn的交换态含量分别由CM的94.8、10.0和34.9 mg·kg~(-1)显著降为CMB的16.6 mg·kg~(-1)、未检测出和1.8 mg·kg~(-1). CM裂解成CMB后, Cr元素残渣态含量显著提高.从元素质量守恒来看, CM制成CMB后Mn、Cu、Zn和Cr损失率分别为29.3%、35.6%、33.5%和3.3%.裂解油中Mn、Cu、Zn和Cr的金属总量分别占CM金属损失量的51.7%、53.0%、32.9%和13.1%. CM裂解成CMB后,91.7%的交换态Mn、几乎100%交换态Cu和97.5%的交换态Zn会随裂解转化为铁锰氧化态、有机结合态和残渣态形式或挥发而降低有效性. 1年盆栽试验结果表明,在CMB处理中,土壤Mn、Cu和Zn交换态含量显著低于CM处理.相关性分析发现,植物体内重金属吸收量与土壤金属有效态含量显著相关,而与总量相关性不明显.由此可见,将鸡粪制成鸡粪炭是一种有效降低Mn、Cu和Zn生物有效性的途径.     

不同母岩区马尾松人工林土壤酶活性及微生物学性质研究

红壤丘陵区马尾松人工林对土壤性质有重要影响。研究马尾松长期种植对该区主要母岩（花岗岩、第四纪红黏土和红砂岩）发育土壤酶活性及微生物学性质的影响。微生物性质结果显示,土壤微生物生物量碳氮在花岗岩区较高,但有机碳在第四纪红黏土区矿化相对强烈;0～20 cm土层,花岗岩区和红砂岩区土壤有机碳相对趋向累积,而20～40 cm土层,第四纪红黏土区土壤有机碳相对累积;花岗岩区林地土壤微生物群落相对稳定,且0～20 cm层土壤微生物群落真菌较多。转化酶活性和脲酶活性在花岗岩和第四纪红黏土区较高;酸性磷酸酶活性在第四纪红黏土区显著较高;各母岩区土壤多酚氧化酶活性无显著性差异;过氧化氢酶活性在花岗岩区显著较高;因此,在马尾松与土壤长期作用下,花岗岩区土壤微生物群落稳定性,生化强度较高,相对适宜马尾松林种植。     

Tree vegetation of the forest-tundra ecotone in the Western Sayan mountains and climatic trends

Parameters of reproduction of the Siberian stone pine (Pinus sibirica), including radial and apical tree increments, the age structure of stands, the amount of young growth, and its distribution along an altitudinal gradient, have been studied in the forest-tundra ecotone of the Western Sayan. The results show that, over the past 30 years, P. sibirica undergrowth has expanded to the mountain tundra belt, the apical and radial tree increments and stand density have increased, and the life form of many P. sibirica plants has changed from prostrate to erect (single-or multistemmed). These changes correlate with the dynamics of summer temperatures and monthly (in May and June) and annual precipitation. The rise of summer temperatures by 1°C promotes the expansion of P. sibirica undergrowth for approximately 150 m up the altitudinal gradient.     

O3浓度升高对银杏及油松BVOCs排放的影响

以生长在沈阳市区内的银杏及油松为试材,开顶式熏气室模拟升高O₃浓度（80 nmol·mol^-1）和正常大气O₃浓度（≈30 nmol·mol^-1）条件,采用GC-FID技术对银杏及油松的异戊二烯和7种单萜类物质的排放速率进行测定,探讨高浓度O₃对单株银杏及油松挥发性有机物排放规律的影响.结果表明,O₃浓度增高可以显著提高银杏和油松的异戊二烯排放速率（p＜0.05）,及银杏Δ3-蒈烯的排放速率（p＜0.05）,其分别达到1.96、 9.71和0.09 μg·(g·h)^-1,而对于其他单萜物质的排放速率,2种树木对高浓度的O₃熏蒸均没有表现出显著的变化;树种不同,排放的BVOCs组成也不同,自然条件下银杏排放的BVOCs以异戊二烯为主,而油松以α-蒎烯为主;高浓度O₃熏蒸下油松释放的异戊二烯达到其BVOCs组成的64.73%,增加大气O₃浓度改变了树木挥发性有机物的组成比例.因此,O₃浓度升高对银杏及油松BVOCs排放规律具有显著影响.     

CO_2和O_3浓度升高及其复合作用对华山松生长及光合日变化的影响

以生长在沈阳市区内的5年生华山松幼树为实验材料,采用开顶箱法,研究高浓度CO2和高浓度O3下华山松生长变化、光合速率的日变化动态以及日光合总量季节变化,进而了解大气CO2浓度升高、O3浓度升高及其复合作用对华山松光合作用及生长的影响.结果表明,①高浓度O3处理后,华山松20～90 d针叶鲜重、干重增长量以及90 d针叶叶长较对照分别降低45.8%、38.9%和15.3%.主侧枝生长与对照相比无显著差异.高浓度O3降低了华山松日光合总量,处理30 d后,针叶净光合速率均显著低于对照,光合速率日变化曲线表现为双峰型,光合"午休"程度强于对照.②高浓度CO2处理后,华山松针叶鲜重、干重20～90 d增长量分别高于对照41.7%和22.2%,而针叶叶长以及主侧枝长未受显著影响.华山松日光合总量高于对照处理,处理30 d、60 d时,净光合速率普遍高于对照.CO2处理90 d时,日变化曲线由双峰变为单峰曲线,极大缓解了光合"午休"现象.③高浓度O3和CO2复合处理后,针叶干重、鲜重增量均低于对照,表明了复合处理后O3伤害的发生,但针叶干重高于O3单因子处理,这表明高浓度CO2可以一定程度上缓解高浓度O3对华山松针叶生长的抑制作用.针叶叶长,主侧枝生长未见明显效应.复合处理后,针叶净光合速率普遍低于对照,华山松日光合总量低于对照而高于O3单独处理,说明高浓度CO2可以通过减缓O3对植物光合的抑制而减少O3伤害.光合速率日变化曲线表现为双峰型.     

维管束植物樟树和马尾松叶组织氮、硫含量指示贵阳地区大气氮、硫沉降的空间变化

同时测定了从贵阳市区到农村3个方向采集的樟树叶、马尾松叶、根际土以及苔藓共计296个样品的氮、硫含量,结合苔藓氮、硫含量估算了相应区域大气氮沉降量和SO_2浓度.结果表明樟树叶氮含量(1.01%~2.37%)和马尾松叶氮含量(0.99%~2.42%)在市区最高,往外明显降低,而在较远农村区域(24 km)又出现回升,反映了农村地区大气输入的氮有所增加;叶硫含量变化范围分别为0.16%~0.43%和0.18%~0.32%,均呈现在市区最高,向外逐渐降低的趋势,在距市区最远处(30~36 km)达到最低值,表明市区的生产生活向大气输入了较高的硫.各区域土壤氮、硫含量均无显著差异,将樟树、松树叶氮、硫含量分别与大气氮沉降量和SO_2浓度(由苔藓氮、硫值计算)进行线性回归分析,发现樟树、松树叶氮含量与大气氮沉降量以及樟树、松树叶硫含量与大气SO_2浓度均呈显著正相关(P0.05).研究表明维管束植物樟树与马尾松叶组织氮、硫含量的变化特征能同时很好地指示贵阳区域大气氮、硫沉降的空间变化.