Signals of tree volume and temperature in a high‐resolution record of pollen accumulation rates in northern Finland     

F. Mazier  A. B. Nielsen  A. Broström  S. Sugita  S. Hicks 《第四纪科学杂志》2012,27(6):564-574

Pollen accumulation rates (PARs) provide a potential proxy for quantitative tree volume (m³ ha^?1) reconstruction with reliable absolute pollen productivity estimates (APPEs). We obtained APPEs for pine, spruce and birch at their range limits in northern Finland under two temperature periods (‘warm’ and ‘cold’) based on long‐term pollen trap and tree volume records within a 14‐km radius of each trap. APPEs (mean ± SE; × 10⁸ grains m^?3 a^?1) tend to be higher for the ‘warm’ periods (pine 123.8 ± 24.4, birch 528.0 ± 398.4, spruce 434.3 ± 113.7) compared with the ‘cold’ periods (pine 95.5 ± 37.3, birch 317.3 ± 282.6, spruce 119.6 ± 37.6), although the difference is only significant for spruce. Using an independent temperature record and the APPEs obtained, we reconstruct a low‐frequency record of pine volume changes over the last 1000 years at Palomaa mire, where a high‐resolution record of Pinus PARs is available. Five phases are distinguished in the reconstruction: moderate pine volume, AD 1080–1170; high volume, AD 1170–1340; low volume, AD 1340–1630; very low volume, AD 1630–1810; and rising pine volume, AD 1810–1950. These phases do not coincide with periods of high or low June–July–August temperatures, and thus appear to reflect regional variations in tree volume, while high‐frequency changes within each time‐period block show variations in PARs in response to temperature. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Light Detection and Ranging for Implementing Water‐Oriented Forest Management in a Semiarid Sub‐Catchment (Valencia,Spain)          下载免费PDF全文

Angela Manrique‐Alba  Antonio D. del Campo  María Gonzalez‐Sanchis 《洁净——土壤、空气、水》2015,43(11):1488-1494

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Crown fuel characteristics and carbon emission from Japanese red pine stands burned by crown fire in Mt. Palgong, South Korea     

Byungdoo LEE  Myoung Soo WON  Yohan LEE  Myung Bo LEE 《山地科学学报》2012,9(5):656-664

Carbon emissions from forest fires are considered an important factor of ecosystem carbon balance and global climate change. Carbon emissions from Japanese red pine stands (Pinus densiflora S. et Z.) burned by crown fire were estimated at Mt. Palgong in Daegu Metropolitan City, and crown fuel characteristics, including crown bulk density, crown base height, and fuel moisture content of Japanese red pine, were analyzed. Total biomass combusted was calculated by subtracting the biomass of burned stands from that of unburned stands exhibiting similar stand structures and site environments. Ten trees in the unburned area and five trees in the burned area were cut by using direct harvesting techniques to estimate crown layer biomass. All biomass sampled was oven-dried and weighed. The dry weight ratios of stems, branches, and needles were 70%, 21%, and 9%, respectively. The available fuel load susceptible to combustion during the crown fire spread was equivalent to 55% of the crown layer biomass. The crown bulk density was 0.24 kg/ m 3 on average. The estimated amount of CO 2 was 23,454 kg CO 2 /ha for the crown layer. These results will be useful for calculating the amount of CO 2 emitted from forest fires and for developing a forest carbon model in P. densiflora forests.  相似文献   

Climate response and radial growth of Pinus tabulaeformis at different altitudes in Qilian Mountains     

Liang Jiao  ChangLiang Qi  RuHong Xue  Ke Chen  XiaoPing Liu 《寒旱区科学》2021,13(6):496-509

In order to test whether the relationship between climate and the radial growth of trees is affected by altitude, altitude variability and time stability of climate-influenced radial growth of a dominant conifer, Chinese pine (Pinus tabulaeformis), in the eastern Qilian Mountains were studied against the background of climate change using dendrochronology. Results show that 1) droughts at the end of the growing season of last year and during the early and middle growing season of the current year were the main limiting factors for the radial growth of Chinese pine at two altitude gradients; this was determined by analyzing the relationship between tree-ring width chronologies and climate factors. 2) The sensitivity of the radial growth of trees to climate change gradually decreased and was affected more by drought stress at a lower altitude. 3) An unstable divergence response was observed in the radial growth at the two altitudes, in response to controlling climatic factors; this observation was based on the moving correlation analysis of growth/climate relationships, and the aggravation of drought stress caused by increasing temperature was the main reason. 4) The growth rate of Chinese pine at the two altitudes increased at first and then decreased, as measured by basal area increment (BAI) modeling. Future temperature rises may have significant effects on mountain forest ecosystems in arid and semi-arid regions. Effective management and protection measures should be taken, according to the response patterns of trees to climate change at different altitude gradients.  相似文献   

Analyzing forest effects on runoff and sediment production using leaf area index     

WU Xiao-Xia  GU Zhu-Jun  LUO Hao  SHI Xue-Zheng  YU Dong-Sheng 《山地科学学报》2014,11(1):119-130

Quantifying the effects of forests on water and soil conservation helps further understanding of ecological functions and improving vegetation reconstruction in water-eroded areas.Studies on the effects of vegetation on water and soil conservation have generally focused on vegetation types or vegetation horizontal distribution densities.However,only a few studies have used indicators that consider the vegetation vertical distribution.This study used the leaf area index(LAI) to investigate the relationship between forests and water and soil conservation in experimental plots.From 2007 to 2010,rainfall characteristics,LAI,and water and soil loss in 144 natural erosive rainfall events were measured from five pure tree plots(Pinus massoniana).These tree plots were located in Hetian Town,Changting County,Fujian Province,which is a typical water-eroded area in Southern China.Quadratic polynomial regression models for LAI and water/soil conservation effects(RE/SE) were established for each plot.The RE and SE corresponded to the ratios of the runoff depth(RD) and the soil loss(SL) of each pure tree plot to those of the control plot under each rainfall event.The transformation LAIs of the LAI–RE and LAI–SE curves,as well as the rainfall characteristics for the different water/soil conservation effects,were computed.The increasing LAI resulted in descending,descending–ascending,ascending–descending,and ascending trends in the LAI–RE and LAI–SE curves.The rainfall frequencies corresponding to each trend of LAI–RE and LAI–SE were different,and the rainfall distributions were not uniform per year.The effects of soil conservation in the plots were superior to those of water conservation.Most of the RE and SE values presented a positive effect on water and soil conservation.The main factor that caused different effects was rainfall intensity.During heavy rains(e.g.,rainfall erosivity R = 145 MJ mm/ha h and maximum 30 min intensity I30 = 13 mm/h),the main effects were positive,whereas light rains(e.g.,R = 70 MJ mm/ha h and I30 = 8 mm/h) generally led to negative effects.When the rainfall erosivity was lower than that of the positive or the negative effects to a threshold and the tree LAI reached a transformation value,the relationships between LAI and RE or SE notably transformed.Results showed that the plottransformation LAIs for water and soil conservation during rainfall events were both approximately 1.0 in our study.These results could be used to come up with a more efficient way to alleviate water and soil loss in water-eroded areas.  相似文献   

马尾松树轮宽度与气候因子关系的地域差异--以九岭山和九连山为例     

赵业思  商志远  王建  郭海婷  周德帅  丁苗 《亚热带资源与环境学报》2014,(4)

在全球变暖背景下,树轮宽度与气候因子关系的地域差异研究,将为预测森林生产力、种群分布等变化提供重要信息。以中国东南地区马尾松为例,利用其分布中心区九岭山和分布南缘九连山两地的树轮样本,分别建立了树轮宽度差值年表,并与两地平均气温、降水量、相对湿度和日照时数4个气候因子做相关分析。结果表明：两地年表均与冬春季（1—3月）平均气温显著正相关,与上一年11月日照时数显著负相关,验证了在中国东南地区利用树轮宽度重建冬春季平均气温的可行性;九岭山年表与上一年气候因子的相关性显著高于九连山地区,表现出气候对分布中心区的马尾松生长产生更为明显的滞后效应,对该差异从两地树轮早材率角度进行了合理的解释;在不区分上一年和当年的前提下,九连山年表与生长季中晚期（7—10月）气温显著负相关,与降水和相对湿度显著正相关,而九岭山年表在该时段内与气温和日照时数显著正相关,与降水和相对湿度显著负相关,这说明生长季中晚期由高温干旱而导致的水分胁迫作用是南界马尾松径向生长的主要气候限制因子,而分布中心区的马尾松径向生长可能受到一定程度的高湿环境制约。  相似文献   

岷江上游大沟流域油松人工幼林生物量组成及其影响因素   总被引：3，自引：1，他引：2  

李武斌  包维楷  何丙辉  吴文妍  李芳兰 《山地学报》2007,25(2):236-244

为了揭示人工林不同层次的生物量组成关系及其影响因素,选择岷江上游大沟流域的油松人工林,调查分析了林分不同层次生物量组成及其关系,探讨了乔木密度、坡向、海拔对生物量的影响。发现:1)两种林龄油松人工林生物量分配基本一致,即,乔木层>灌木层>草本层;乔木各构件生物量大小顺序为:枝>干>叶>根>果/皮。同时指出,枝叶对下木层生物量的影响显著。2)乔木密度显著控制了林分生物量及其组成,在本调查范围内坡向的影响似乎不明显;海拔对22 a油松影响显著,而24 a的不显著;综合分析表明,本区域内,22 a油松保持在3 800株/hm2左右和24 a在3 500株/hm2左右时,有助于林分生物量的稳定与提高,促进生态系统功能的恢复。  相似文献