冰雪灾害对中亚热带人工针叶林净初级生产力的影响

结合中亚热带江西千烟洲人工针叶林2005、2008和2011年3次树木清查数据以及树木相对生长方程,比较了2008年1月南方冰雪灾害前后的NPP,评价了森林生态系统灾后的恢复能力。结果表明:乡土树种马尾松(Pinus massoniana)与杉木(Cunninghamia lanceolata)比外来树种湿地松(Pinus elliottii)抗灾害能力强;在个体水平上,胸径(D)较大的树木抗灾害能力较差。灾后马尾松与杉木的D增长率降低,而湿地松增大。冰雪灾害导致大量碳(10.44 t C/hm2)从乔木层碳库转移到死生物量碳库,占乔木层碳储量的18.28%。灾前NPP和碳利用效率(CUE)分别为736.23 g C m-2a-1和0.41;灾后经过近4年的恢复,NPP和CUE分别为683.08 g C m-2a-1和0.38。     

中亚热带湿地松(Pinus elliottii)人工林生长过程

基于树干解析和树轮分析,结合野外调查,揭示了我国主要外来树种--湿地松(Pinus elliottii)的生长规律,从而为人工林经营管理和生态系统服务功能评估提供了依据。2005年调查了1948年江西吉安青原山引种后存留的564株湿地松(1954 1958年生)。胸径(DBH, diameter at breast height)平均值为34.2 cm(18.4-58cm),树高平均值为19.5 m(9-33m)。青原山湿地松树轮分析结果显示:52年间,年树轮宽度增长量平均值为0.32 cm,最大年增长量不超过1.14 cm。胸径年生长量总体上呈下降趋势,直径生长高峰出现在10a左右;林龄达到20a左右时,直径年生长量开始下降;林龄40a后,生长变得极为缓慢。距青原山西南100km的千烟洲湿地松林(20年生)胸径和树高平均值分别为15.9 cm和11.0 m;20a的胸径生长量平均值为0.86 cm;材积方程为V= 0.0000213 D^2.9870924(V为带皮材积,D为胸径)。千烟洲湿地松林生物量低于同期营造的马尾松(Pinus massoniana)林生物量,也明显低于中亚热带地带性植被樟树(Cinnamomum camphora)林的生物量。经比较发现,引种营造的湿地松林,其生长量远不如原产地美国佛罗里达州湿地松林。     

千烟洲针叶林的比叶面积及叶面积指数

 根据实测数据计算了湿地松（Pinus elliotii）、马尾松(P. massoniana) 和杉木 (Cunninghamia lanceolata)不同年龄、不同类型叶片的生 物量和比叶面积，并结合样地调查数据和相对生长方程计算了中国科学院千烟洲试验站20年生湿地松林、马尾松林、杉木林和针叶混交林的叶 面积指数。根据拟合结果，选择如下方程计算3个树种的叶生物量：湿地松W=12.0741D^2.1515、马尾松W=6.9727D^2.1973和杉木W=5.2619D^2.3027 。湿地松林的叶生物量（0.822 kg•m^-2）最大，其次为针叶混交林（0.679 kg•m^-2），马尾松林和杉木林相差不大（分别为林0.5 28和0.572 kg•m^-2）。不同树种、不同年龄、不同类型叶片的比叶面积比较发现，新叶的比叶面积大于老叶，三针一束叶的比叶面积略大于两针一束叶， 马尾松的平均半比表面积（8.62 m²•kg^-1）大于湿地松（6.04 m²•kg^-1） 和杉木（7.91 m²•kg^-1）。胸径与单木叶片半表面积之间的经验方程 为：湿地松 LA=0.073D^2.1515、马尾松LA=0.060D^2.1973和杉木LA=0.042D^2.3027。据此计算湿地松林的叶面积指数为5.03，马尾松林和杉木 林为4.31，针叶混交林为4.77，该结果比利用CI_110植被冠层数字图像仪测得的结果偏大。     

高寒湿地土壤微生物区系组成对氮添加的响应

土壤微生物是土壤养分循环的关键驱动者,对土壤环境变化感应明显,氮是陆地生态系统的限制元素之一,其改变可能会给生态系统物种多样性造成一定影响.为了解高寒湿地土壤微生物组成对氮添加的响应,以青海湖流域高寒湿地为研究对象,通过(0 g·m-2、0.5 g·m-2、1 g·m-2、1.5 g·m-2、2 g·m-2、2.5 g...     

长江口九段沙盐沼湿地芦苇和互花米草生物量及碳储量

2010-2012年,采用野外采样和实验室测定相结合的方法,研究了长江口九段沙芦苇、互花米草植被带生物量的季节动态和碳储存能力.结果表明:两种植物生物部分(地上、地下、枯立物生物量之和)的有机碳储量均为秋季最高、春季最低.地上活体互花米草单位面积的平均碳储量(445.81 g·m-2)高于芦苇(285.52 g·m-2),芦苇枯立物的平均碳储量(203.15 g·m-2)低于互花米草(315.28 g· m-2),但芦苇区土壤表层(0 ～30 cm)有机碳储量(1048.62 g·m-2)约为互花米草区(583.33 g· m-2)的2倍.芦苇区的碳储存能力(3212.96g· m-2)总体上高于互花米草区(2730.42 g·m-2).表明保护芦苇群落对于维护盐沼湿地的碳汇功能具有重要意义.     

崇明东滩湿地不同盐沼植物群落土壤碳储量分布

海岸带盐沼植被的高生产力对湿地土壤碳库的形成具有重要意义.本文研究了长江口崇明东滩湿地3种主要盐沼植物(芦苇、互花米草和海三棱草)群落生物量差异、土壤碳储量时空动态和垂向分布特征.结果表明:湿地盐沼植被总生物量表现为互花米草群落(5750.7 g·m-2)芦苇群落(4655.1 g·m-2)海三棱草群落(812.7 g·m-2),且地上生物量在夏、秋季最高,地下生物量在冬季最高.湿地土壤碳储量(0~50 cm)在春季最低,随后逐渐增加,至冬季达到最大值.土壤碳储量年增量从高潮滩向低潮滩递减,表现为芦苇群落(711.8 g·m-2)互花米草群落(646.2 g·m-2)海三棱草群落(185.3 g·m-2)光滩(65.6 g·m-2).光滩土壤碳储量在25~30 cm处最高,海三棱草、互花米草和芦苇群落土壤碳储量分别在10~15、30~35和30~40 cm处达到最大值,且不同群落土壤碳储量与植被地下生物量具有显著的线性关系.     

滇西北高原纳帕海湿地湖滨带优势植物生物量及其凋落物分解

选取滇西北高原湿地纳帕海湖滨带优势植物茭草(Zizania caducifolia)、水葱(Scirpus tabernaemontani)和刘氏荸荠(Heleocharis liouana),研究其生物量及其凋落物分解特征,结果表明:水葱、茭草、刘氏荸荠为纳帕海湿地湖滨带单优植物群落,均具有较高的地上生物量,不同植物群落地上生物量不同,其中,茭草地上生物量(853.6±58.2)g·m-2·a-1显著高于水葱(730.7±7.8)g·m-2·a-1与刘氏荸荠(338.9±32.6) g·m-2·a-1的地上生物量.3种植物群落凋落物分解速率不同、并随月平均气温升高均呈增加的趋势,其中,刘氏荸荠分解速率k值最大(0.067±0.0026)、茭草(0.062±0.0072)其次、水葱最小(0.039±0.0062).凋落物经过1年的分解,水葱、茭草和刘氏荸荠凋落物存留率分别为(62.0±8.8)％、(47.5±9.0)％和(44.5±7.9)％.综合3种湖滨带植物地上生物量与凋落物年分解,水葱地上生物量年存留量(453.1±4.9)g·m-2·a-1显著高于茭草(405.4±27.7)g·m-2·a-1和刘氏荸荠(150.9±14.5) g·m-2·a-1.研究进一步表明滇西北高原湿地湖滨带植物具有极高的生物量存留率,成为该类型湿地生态系统碳汇功能的基础,其碳汇过程及其贡献率需要进一步深入研究.     

湿地松林分结构调整对土壤活性有机碳的影响

以21 a湿地松纯林为对照,研究了间伐后补植阔叶树(间伐补阔,补植枫香)对不同年限(3、6、9 a)湿地松林分和21 a湿地松×枫香混交林土壤活性有机碳的影响.结果表明:间伐补阔后,6和9 a湿地松林分的土壤可溶性有机碳(DOC)、易氧化有机碳(ROC)和微生物生物量碳(MBC)含量均比21 a湿地松纯林显著增高;21 a湿地松×枫香混交林的土壤各活性碳组分含量显著高于3、6、9 a湿地松林分,其DOC、ROC和MBC含量分别比21 a湿地松纯林增加113.1%、53.3%和54.6%.说明间伐补阔结构调整是改善人工湿地松纯林土壤生态功能的有效措施.     

森林类型对土壤有机质、微生物生物量及酶活性的影响

以澳大利亚南昆士兰州典型森林类型——湿地松、南洋杉和贝壳杉林为对象,开展土壤可溶性有机碳和氮(SOC和SON)、微生物生物量碳和氮(MBC和MBN),以及土壤酶活性的研究,剖析森林类型对土壤质量的影响.结果表明:不同林型土壤SOC、SON含量分别在552 ～1154 mg·kg-1和20.11～57.32mg·kg-1;MBC、MBN分别在42～149 mg·kg-1和7～35 mg·kg-1.MBC、MBN之间呈显著相关.土壤几丁质酶、酸性磷酸酶、碱性磷酸酶和β-葡萄糖苷酶的活性分别为2.96 ～7.63、16.5 ～29.6、0.79 ～ 3.42和3.71 ～9.93 μg ·g-1·h-1,亮氨酸氨肽酶活性为0.18～0.46 μg·g-1·d-1.不同林型土壤SOC含量,以及土壤几丁质酶和亮氨酸氨肽酶活性为湿地松林、南洋杉林、贝壳杉林依次降低;而SON含量为南洋杉林＞贝壳杉林＞湿地松林,且南洋杉林的SON含量显著(P＜0.05)高于湿地松林;MBC和MBN以及碱性磷酸酶活性为贝壳杉林＞湿地松林＞南洋杉林;酸性磷酸酶和β-葡萄糖苷酶活性为湿地松林＞贝壳杉林＞南洋杉林.在土壤生物代谢因子中,MBC、MBN、SON和亮氨酸氨肽酶对不同森林类型土壤影响较大.     

土地利用类型对千烟洲森林土壤碳矿化及其温度敏感性的影响

土壤有机质分解是陆地生态系统碳循环的重要环节,它不仅受温度和水分的影响,还对土地利用变化十分敏感.以中国科学院千烟洲生态试验站的柑橘园和湿地松人工林为对象,研究不同土地利用类型、温度(5、10、15、20和25 ℃)和水分(30%、60%和90%饱和含水量)对土壤碳矿化及其温度敏感性的影响.结果表明： 土地利用类型、温度和水分对土壤碳矿化都具有显著影响,且各因素间存在显著的交互效应.柑橘园和湿地松人工林土壤碳矿化速率均与温度呈正相关,60%饱和含水量处理下土壤碳矿化速率最高.在相同的温度和水分处理下,柑橘园土壤碳矿化量显著高于湿地松林.土地利用类型和水分对土壤碳矿化温度敏感性(Q₁₀)具有显著影响.培养7和42 d,土壤碳矿化的温度敏感性随水分升高而上升;柑橘园温度敏感性高于湿地松林,且水分越高差异越明显.包含温度和水分的双因素模型可以很好地模拟土壤碳矿化对温度和水分的响应,温度和水分共同解释土壤碳矿化变异的79.9%～91.9%.     

多样化松林中昆虫群落多样性特征

马尾松和湿地松是我国南方的2种主要松树。通过对6种不同林分结构下的马尾松林和湿地松林内昆虫群落调查与多样性指数分析,表明2种松树内的昆虫种类和数量无显著差异,混交林中的昆虫群落的种类和数量比纯林多,尤其以捕食天敌类群的种类和数量更为明显。整个昆虫群落和植食类群多样性指数以湿地松林内较大,而天敌(捕食类群和寄生类群)多样性指数则以马尾松林较高。从不同林分结构下昆虫多样性的比较来看,混交林内昆虫群落多样性指数波动较小,明显地高于纯林。但不同林分结构下昆虫多样性随水平分布和垂直分层格局而变化,松树北面和东面各样地之间的昆虫群落多样性指数差异显著,而南、西面之间差异较小;树冠层各样地之间的差异达极显著水平,而枯枝落叶层和树干层之间差异不显著。由此,还进一步讨论了混交林中昆虫群落稳定性问题。     

Ice‐storm disturbance and long‐term forest dynamics in the Adirondack Mountains

Ice storms cause periodic disturbance to temperate forests of eastern North America. They are the primary agents of disturbance in some eastern forests. In this paper, a forest gap model is employed to explore consequences of ice storms for the long‐term dynamics of Tsuga canadensis‐northem hardwoods forests. The gap model LINKAGES was modified to simulate periodic ice storm disturbance in the Adirondack Mountains of New York. To adapt the gap model for this purpose, field data on ice storm disturbance are used to develop a polytomous logistic regression model of tree damage. The logistic regression model was then incorporated into the modified forest gap model, LINK ADIR, to determine the type of damage sustained by each simulated tree. The logistic regression model predicts high probabilities of bent boles or severe bole damage (leaning, snapping, or uprooting) in small‐diameter trees, and increasing probability of canopy damage as tree size increases. Canopy damage is most likely on gentle slopes; the probability of severe bole damage increases with increasing slope angle. In the LINKADIR simulations, tree damage type determines the probability of mortality; trees with severe bole damage are assigned the highest mortality rate. LINKADIR predicts Tsuga canadensis dominance in mesophytic old‐growth forests not disturbed by ice storms. When ice storms are simulated, the model predicts Acer saccharum‐dominated forests with higher species richness. These results suggest that ice storms may function as intermediate disturbances that enhance species richness in forested Adirondack landscapes.     

Spatial distribution and temporal dynamics of high‐elevation forest stands in southern Siberia

Aim To evaluate the hypothesis that topographic features of high‐elevation mountain environments govern spatial distribution and climate‐driven dynamics of the forest. Location Upper mountain forest stands (elevation range 1800–2600 m) in the mountains of southern Siberia. Methods Archive maps, satellite and on‐ground data from1960 to 2002 were used. Data were normalized to avoid bias caused by uneven distribution of topographic features (elevation, azimuth and slope steepness) within the analysed area. Spatial distribution of forest stands was analysed with respect to topography based on a digital elevation model (DEM). Results Spatial patterns in mountain forests are anisotropic with respect to azimuth, slope steepness and elevation. At a given elevation, the majority of forests occupied slopes with greater than mean slope values. As the elevation increased, forests shifted to steeper slopes. The orientation of forest azimuth distribution changed clockwise with increase in elevation (the total shift was 120°), indicating a combined effect of wind and water stress on the observed forest patterns. Warming caused changes in the forest distribution patterns during the last four decades. The area of closed forests increased 1.5 times, which was attributed to increased stand density and tree migration. The migration rate was 1.5 ± 0.9 m year^–1, causing a mean forest line shift of 63 ± 37 m. Along with upward migration, downward tree migration onto hill slopes was observed. Changes in tree morphology were also noted as widespread transformation of the prostrate forms of Siberian pine and larch into erect forms. Main conclusions The spatial pattern of upper mountain forests as well as the response of forests to warming strongly depends on topographic relief features (elevation, azimuth and slope steepness). With elevation increase (and thus a harsher environment) forests shifted to steep wind‐protected slopes. A considerable increase in the stand area and increased elevation of the upper forest line was observed coincident with the climate warming that was observed. Warming promotes migration of trees to areas that are less protected from winter desiccation and snow abrasion (i.e. areas with lower values of slope steepness). Climate‐induced forest response has significantly modified the spatial patterns of high‐elevation forests in southern Siberia during the last four decades, as well as tree morphology.     

Tropical montane forest ecotones: climate gradients, natural disturbance, and vegetation zonation in the Cordillera Central, Dominican Republic

Aim We examined relationships between climate–disturbance gradients and patterns of vegetation zonation and ecotones on a subtropical mountain range. Location The study was conducted on the windward slopes of the Cordillera Central, Dominican Republic, where cloud forest appears to shift in a narrow ecotone to monodominant forest of Pinus occidentalis. Methods Climate, disturbance and vegetation data were collected over the elevation range 1100–3100 m and in 50 paired plots along the ecotone. Aerial photographs were georeferenced to a high‐resolution digital elevation model in order to enable the analysis of landscape‐scale patterns of the ecotone. Results A Shipley–Keddy test detected discrete compositional ecotones at 2200 and 2500 m; the distributions of tree species at lower elevations were continuous. The elevation of the ecotone determined with aerial photographs was fairly consistent, namely ± 164 m (SD) over its 124‐km length, but it exhibited significant landscape variation, occurring at a lower elevation in a partially leeward, western zone. The ecotone also occurred significantly lower on ridges than it did in drainage gullies. Ecotone forest structure and composition differed markedly between paired plots. In pine paired plots, the canopy height was 1.7 times higher and the basal area of non‐pine species was 6 times lower than in the cloud forest directly below. Fire evidence was ubiquitous in the pine forest but rare in the abutting cloud forest. Mesoclimate changed discontinuously around the elevation of the ecotone: humidity and cloud formation decreased markedly, and frost frequency increased exponentially. Main conclusions The discreteness of the ecotone was produced primarily by fire. The elevational consistency of the ecotone, however, resulted from the overarching influence of mesoclimate on the elevational patterns of fire occurrence. Declining temperature and precipitation combine with the trade‐wind inversion to create a narrow zone where high‐elevation fires extinguish, enabling fire‐sensitive and fire‐tolerant taxa to abut. Once established, mesotopography and contrasting vegetation physiognomy probably reinforce this boundary through feedbacks on microenvironment and fire likelihood. The prominence of the pine in this study – and of temperate and fire‐tolerant taxa in subtropical montane forests in general – highlights the importance of climate‐disturbance–biogeography interactions in ecotone formation, particularly where fire mediates a dynamic between climate and vegetation.     

南方红壤区3种典型森林恢复方式对植物群落多样性的影响

合理的森林恢复方式能提高植物多样性,进而提高生态系统服务功能.在我国南方红壤区研究了3种典型森林恢复方式(引进种恢复的湿地松(Pinus elliottii)人工林本地种恢复的马尾松(Pinus massoniana)人工林和自然恢复的天然次生林)的植物区系构成和植物群落多样性.结果表明:(1)湿地松人工林有155种植物,隶属66科118属,马尾松人工林有137种植物,隶属59科97属;天然次生林有226种植物,隶属86科160属,3种森林恢复方式的乔木层、灌木层和草本层的优势科属明显不同,马尾松人工林的优势物种和天然次生林更相似;(2)天然次生林的植物区系基本构成、植物区系类型种类高于马尾松人工林和湿地松人工林,并且天然次生林的温带成分比例高于湿地松人工林;(3)恢复方式对植物群落的多样性指数有显著影响,天然次生林的物种丰富度、辛普森指数明显高于马尾松人工林和湿地松人工林,两种人工林之间差异不显著;(4)3种森林恢复方式的植物群落结构存在显著差异,相比湿地松人工林,马尾松人工林的植物群落组成与天然次生林更相似.总之,自然恢复的天然次生林植物群落多样性高于人工恢复的马尾松人工林和湿地松人工林,本地种马尾松人工林在维持区域植物群落结构功能上优于引进种湿地松人工林.     

陕西省栎黄枯叶蛾蛹的空间分布

栎黄枯叶蛾(Trabala vishnou gigantina Yang)是近年来在陕西吴起沙棘林中大面积暴发的一种食叶害虫,为了解其种群空间结构,有效控制危害,利用地统计学等方法,对不同坡向和疏密度沙棘纯林中的栎黄枯叶蛾蛹的空间分布进行了研究。结果表明:栎黄枯叶蛾化蛹的高峰期为8月中旬,雄性幼虫较雌性幼虫平均早3.7 d化蛹;蛹在阴坡的东南向和阳坡的西、北两方向分布比例最大;在距沙棘树基部30.00—75.00 cm范围处分布密集。由全方向的变异函数曲线分析得知:阴坡密林、阴坡疏林、阳坡密林、阳坡疏林中,栎黄枯叶蛾蛹的空间依赖范围分别为95.609、47.379、79.238、42.415 m,空间变异值分别为0.760、0.561、0.649、0.407;且在阴阳两坡向的密林中均呈聚集分布,疏林中均呈随机分布。用Kriging插值方法生成的空间分布图显示蛹在空间分布上存在一定的边缘效应,且方向性较明显。     

车八岭山地常绿阔叶林冰灾后林木受损的生态学评估

从植物生态学的角度对2008年初南方冻雨冰雪灾害对典型的亚热带山地常绿阔叶林造成的损害情况做了研究。对12个优势种和亚优势种的受灾情况做了对比分析,对不同径级和不同地形因子下林木抵抗冻雨灾害的差异做了对比。统计检验结果显示林木受损程度存在显著的种间差异、径级差异和地形级差异。优势种米槠(Castanopsis carlesii)比多数亚优势种受害更严重;各树种抗冻雨灾害能力以山茶科和樟科的种较强,而壳斗科的多个种,如米槠、栲(C.fargesii)受灾较为严重;林木的受损比例随着胸径(diameter at breast height,DBH)增加而增大;在未受灾的各级林木中,超过70%的个体集中在最小一级径阶(1-5cm)。χ2检验显示坡度、坡向、坡位等地形因子对林木受损状况有显著的影响,随着坡位上升,林木受损程度逐渐加重,上坡位的林木受损比例最大,下坡位最小,这可能与随着坡位升高,迎风面降温效果更迅速有关。对于坡向和坡度而言,位于半阳坡的林木受灾比例显著高于半阴坡,位于坡度级III(15°-25°)、IV(25°-35°)、V(35°-45°)上的林木受灾最严重。该研究结果对于亚热带常绿阔叶林的保育和应对未来可能再次发生的冰雪灾害有重要意义;同时对于森林恢复和演替、乡土阔叶树种的选育及森林经营等方面的研究和应用也有重要的参考价值。     

Analysis of topography and vegetation distribution using a digital elevation model: case study of a snowy mountain basin in northeastern Japan

This study examines the relations between the local variations in vegetation and topography using logistic regression (LR) and GIS in a snowy basin in the Ohu Mountains of northeastern Japan. The spatial distribution of seven vegetation classes interpreted from aerial photographs—(a) large-sparse crown beech forest, (b) middle-dense crown beech forest, (c) dwarf beech scrub, (d) dwarf bamboo thicket, (e) Japanese white pine forest, (f) snow-avalanche scrub or meadow, and (g) riparian forest—was analyzed with terrain parameters derived from a 10 m digital elevation model (10 m DEM) and parameters of landslide distribution and surface geology. While large-sparse crown beech forests dominate the slopes, smaller crown beech forests or scrubs are often found on the west-facing (i.e., windward side) upper parts of slopes and crests. On the contrary, snow-avalanche scrubs or meadows are found on the leeward side of steep slopes and concave plan curvatures. Dwarf bamboo thickets are often found on east-facing (i.e., leeward side) gently sloping crests, where the snow remains until summer. Japanese white pine forests respond positively to sharp ridges, whereas riparian forests show a positive response to the gently sloping lower parts of slopes and bottomlands at low elevation. The heterogeneous vegetation distribution in the basin indicates differences in site conditions (e.g., soil–water conditions), and the existence of various disturbance regimes induced by the strong winter monsoon with heavy snowfall, snow movements (e.g., avalanches), and temporal differences in snowmelt on different topographies. The estimated vegetation maps could be used for forest management and restoration.