长白山阔叶红松林径级结构动态模拟和优化经营

以原始阔叶红松林为研究对象,采用密度依赖矩阵模型,模拟了自然生长预案下林分径级结构的动态变化,分析了一种择伐预案对林分径级结构的影响,计算了7种不同择伐强度下森林的恢复期。结果表明:原始阔叶红松林比较稳定,但也有比较缓慢的自然生长,林分株数密度呈下降趋势,符合森林的自然稀疏规律,随着时间的推移,各径阶株数的变化速度逐渐减弱,趋于稳定,验证了演替顶极理论。以生长量、收获量、保留林分结构和采伐费用为森林经营效果的评价指标,则20%的采伐强度、35年采伐周期和25%的采伐强度、45年的采伐周期的2种方案较优。     

气候变化、林火和采伐对大兴安岭森林碳储量的影响

大兴安岭林区林火发生的频率受气候变化的影响将会增加,可能会增加该地区森林生态系统碳损失.本研究通过耦合森林生态系统模型和森林景观模型以模拟未来百年大兴安岭森林碳储量动态变化,量化气候变化、林火和采伐对森林碳储量的影响.结果表明: 虽然采伐和林火会抵消相当一部分由气候变化增加的碳储量,但气候变化仍然能够增加大兴安岭森林碳储量.未来100年该地区森林地上和土壤有机碳储量将会分别增加9%～22%和6%～9%.短期(0～20年)气候变化对大兴安岭森林碳储量的影响大于同期林火的影响,中期(30～50年)和长期(60～100年)气候变化对森林碳储量的影响小于林火和采伐的影响.由于未来大兴安岭地区气候变化及其林火干扰存在不确定性,导致未来该地区森林碳储量存在较大的不确定性.未来100年大兴安岭森林地上碳储量和土壤有机碳储量不确定性分别为12.4%～16.2%和6.6%～10.4%.为准确估算我国北方森林生态系统碳储量,需要考虑种子传播、林火和采伐的影响.     

1896年和1986年黑龙江省几种森林景观的特征变化

通过用地理信息系统软件对 1896和 1986年的黑龙江省的森林分布图中提取的 5种森林景观进行处理和计算得到 :在 90年中 ,云杉 (Picea)、冷杉 (Abies)林、樟子松 (Pinussylvestrisvar.mongolicaLitvin)林和阔叶红松 (PinuskoraieusisSieb .etZucc .)林斑块总面积分别减少 87%、40 %和 84%。北纬 5 1°以北地区阔叶林斑块面积增加 5 0 0 % ,北界向西北扩展约 2 90km。云杉、冷杉林和针阔混交林斑块在 1986年的斑块的分维数小于 1896年的斑块的分维数 ,而樟子松林、阔叶红松林和阔叶林的 1986年斑块分维数都分别大于 1896年的分维数。云杉、冷杉林、樟子松林、阔叶红松林和阔叶林景观破碎化增加。云杉、冷杉林 ,樟子松林和阔叶红松林转化为针阔混交林的比率大于各自保留的比率。     

自然与人工恢复对川西高山采伐迹地植物群落特征的影响

以天然林为对照,选取自然恢复(40年)与人工恢复(30、40和50年)下川西高山采伐迹地,研究不同恢复途径下川西高山采伐迹地的植物群落特征。结果表明: 采伐迹地经过40年的自然恢复演替成为高山绣线菊次生灌丛,人工恢复后成为川西云杉林,与天然林群落相似性分别为极不相似(0.19)和中等不相似(0.28~0.49)。自然与人工恢复采伐迹地的灌木层物种多样性均低于天然林,而草本层高于天然林。随着恢复年限的增加,人工林胸高断面积、蓄积量、径级幅度、物种多样性指数及与天然林群落的相似性均呈现增加的趋势,而林分密度逐渐减小。人工林面临林分密度较高、结构不合理、同龄纯林和林下更新差等问题。     

长白山阔叶红松林采伐迹地土壤养分含量动态研究

采用对比实验,对不同采伐年限的长白山阔叶红松林采伐迹地土壤养分含量变化进行了分析与研究．结果表明,不同采伐年限的采伐迹地土壤养分含量差异很大．林地土壤pH值随着伐后时间的推移而出现一个先下降后上升的过程,表层土壤在伐后5年的酸性最强,10～20cm层土壤在伐后10年酸性最强;土壤有机质含量、全量养分含量和速效养分含量均在采伐初期2～5年增加,随后又迅速减少,尤其是表层土壤变化更为明显;土壤阳离子交换量(CEC)及交换性Ca、Mg也都表现出相同的变化趋势．因此,森林采伐后应及时人工造林、更新进行植被恢复,可将养分固定而减少和防止土壤养分的流失．     

矩阵模型在森林择伐经营中的应用

采用矩阵模型预测未干扰下长白山阔叶红松林不同初期密度和直径分布林分300年的动态生长过程,比较12种不同采伐方案(最小采伐直径分别为70、60、50、40cm,采伐周期分别为10、20、30年)经过300年采伐保留林分的密度、断面积和林分收获量。结果表明,无论初始状态如何,未干扰林分经过约200多年后变化趋于平稳,径阶结构、断面积均能达到近似相等的稳定状态;采伐以最小采伐直径60cm、采伐周期20年较适宜。得出了不同采伐方案的收获量及保留林分各因子变化规律。     

大兴安岭呼中林业局森林景观格局变化及其驱动力

以大兴安岭呼中林业局为研究区,利用TM数据、森林资源清查数据和采伐统计资料,结合野外调查,以GIS为技术手段,剖析研究区1989～2000年景观变化,结果表明该区主要景观类型为针叶林、针阔混交林和阔叶林,这3种类型面积总比例达90%以上,其他景观类型面积比例小于10%,主要有荒草地、火烧迹地、采伐迹地、沼泽、居民点和道路.10a间景观由原有的大面积连续的针叶林为基质、小面积的阔叶林和针阔混交林斑块散布其中的格局,转变成大面积针阔混交林为基质的格局.研究区1989年是成过熟林、高公顷蓄积量、高郁闭度占优势的景观,2000年中幼龄林、低公顷蓄积量和低郁闭度森林面积增大,并趋于连续,形成低质量的相对均质化的景观.最后,结合历史资料,通过比较分析火烧、人工更新、土地利用和人为采伐活动这几种主要驱动力的特征,论证了采伐活动在该地区景观变化中所发挥的主导作用.     

气候变化和不同强度造林对大兴安岭主要树种林分信息和地上生物量的长期影响

气候变化及相应火干扰在不同尺度上影响着我国大兴安岭地区森林动态,且在未来的影响可能继续加剧。为了提高森林生态功能和应对气候变暖,国家在分类经营基础上全面实施抚育采伐和补植造林,效果较好,但抚育采伐对森林主要树种的长期影响知之甚少,其在未来气候下的可持续性也有待进一步评估,同时,探讨造林措施对未来森林的影响也显得尤为重要。本文运用森林景观模型LANDIS PRO,模拟气候变化及火干扰、采伐和造林对大兴安岭地区主要树种的长期影响。结果表明:1)模型初始化、短期和长期模拟结果均得到了有效验证,模拟结果与森林调查数据之间无显著性差异(P0.05),基于火烧迹地数据的林火干扰验证亦能够反映当前火干扰的效果,模型模拟结果的可信度较高;2)与当前气候相比,气候变暖及火干扰明显改变了树种组成、年龄结构和地上生物量,B1气候下研究区森林基本上以针叶树种为主要树种,A2气候下优势树种向阔叶树转变;3)与无采伐预案相比,当前气候下,抚育采伐使落叶松的林分密度和地上生物量分别降低了(165±94.9)株/hm~2和(8.5±5.1) Mg/hm~2,增加了樟子松、白桦和云杉等树木株数和地上生物量(3.3—753.4株/hm~2和0.2—4.0 Mg/hm~2),而对山杨的影响较小;B1和A2气候下抚育采伐显著改变林分密度,降低景观尺度地上生物量,进而表现为不可持续;4)B1气候下,推荐实施中低强度造林预案(10%和20%强度),在A2气候下,各强度造林均可在模拟后期增加树种地上生物量。     

气候变化、林火和营林措施对寒温带典型森林生态弹性的影响

生态弹性是森林生态系统在遭受外在扰动后恢复到稳定状态的能力,是森林资源可持续发展的重要目标之一,且森林生态弹性对诸如气候变化、林火和营林措施等外部因子的影响较为敏感.探究这些外部因子对森林生态弹性的影响在未来森林生态系统管理方面有重要意义.本研究首先从森林组成、结构和功能等方面选取指标因子并估算了森林生态弹性值,然后运用LANDIS PRO模型,模拟气候变化、林火干扰和营林措施等对寒温带典型森林生态弹性的影响,并探讨了当前抚育采伐方案在未来气候下的可持续性.结果表明: 模型初始化的2000年林分密度和胸高断面积与2000年真实景观较为吻合,模拟的2010年森林景观与野外调查数据无明显差异,基于当前林火干扰状况的模拟结果与火烧迹地调查数据基本匹配,说明林火模块能很好地模拟当前研究区林火发生状况.林火干扰增加30%将会使该区模拟期内景观水平上森林生态弹性提高15.7%～40.8%,而林火干扰增加200%则会降低该区4.4%～24.6%的森林生态弹性.短期和中期林火干扰增加对森林生态弹性的影响大于气候变化的影响.与当前预案相比,B1气候(林火增加30%预案)和A2气候(林火增加200%预案)对整个模拟阶段景观尺度森林生态弹性的影响分别处于-15.9%～38.9%和-60.4%～34.8%范围内.与无采伐预案相比,B1和A2气候下在整个模拟时期内若继续实施当前抚育采伐方案,将不利于景观水平森林生态弹性的提高.在B1气候(林火增加30%预案)下,在各模拟时期内无需实施任何营林措施;而在A2气候(林火增加200%预案)下,建议实施中、高强度种植的营林措施以提升景观水平森林生态弹性.     

气候变化条件下小兴安岭林区森林采伐面积模拟

运用空间直观景观模型LANDIS6.0PRO,以采伐面积代替蓄积量作为采伐量,模拟了气候变化条件下,不同采伐强度交替采伐(交替时间分别为10、20、30年)情况下小兴安岭地区2000—2400年间当前采伐方案和11组模拟采伐预案下的森林采伐面积比.结果表明:不同采伐强度的交替进行,一定程度上可以增加研究区采伐面积;与当前采伐方案相比,短期内(10～30年),研究区模拟预案下每10年的采伐面积将增加3%～5%,中期(40～60年)内,研究区模拟预案下每10年的采伐面积将增加2.5%～7%,长期(70～100年)内,研究区模拟预案下每10年的采伐面积将增加3.5%～8%.总体上,研究区当前总采伐面积仍然过高,改变采伐模式虽然可以在一段时间内增加采伐面积,但不具有可持续性.若使研究区森林可持续发展,还需降低采伐强度、转变森林经营管理理念,变可持续林业产出为森林生态系统可持续管理.     

林窗模型BKPF模拟红松针阔叶混交林群落对气候变化的潜在反应

用森林动态模型ＢＫ荭松针阔叶混交林群落在气候变化和ＣＯ２倍增后的反应得出,在气候变化５０ａ后现存的天然红松林林木总株数减少２０％以上,地上部分生物量将减少９０％以上,蒙古栎的生物量占锯林分的５７％以上,林分生产力与现在气候条件下比较接近,略高４％,但主要以蒙古栎、山杨、白桦为主,林分叶面积指数大幅度减少。     

季节增温方式对小兴安岭红松针阔混交林演替的潜在影响

应用林窗模型LINKAGES对小兴安岭红松针阔混交林在不同季节增温方式下的未来演替过程进行了模拟预测.以温度增加5℃、降水无明显变化作为未来变暖气候的模拟假设,共设计3种气候变暖方式预案,分别为冬季增温幅度大于夏季、冬季与夏季增温幅度相同以及冬季增温幅度小于夏季.模拟结果表明,当冬季增温幅度大于夏季时,小兴安岭现存林分的演替受气候变暖的影响相对最小,树种组成仍然能够保持较为稳定的针阔混交林状态;当冬季增温幅度小于夏季时,现存林分的演替受气候变暖的影响最显著,树种衰退最迅速.可见,小兴安岭针阔混交林的演替与未来的增温方式关系密切,上限温度是现存树种能否继续存活的重要决定因子.     

Secondary succession and effects of clear-logging on diversity in the subtropical forests on Okinawa Island,southern Japan

In order to clarify the recovery process of the subtropical forest on Okinawa Island, southern Japan, biomass accumulation and the successional trend of species diversity with time were investigated by comparing plots of old-growth and clear logged secondary forests. Self-thinning was an important factor in the development of young secondary forests, and the small variance in tree size within a stand was related to the stand not being fully stratified after clear-cutting. A large variance of size structure in old secondary and old-growth forests implies re-initiation of the understorey. Additionally, the trajectory of stand development indicated that the subtropical forest quickly recovered aboveground biomass, which reached its upper limit at about 50 years after disturbance. However, there was a large distinction in species diversity between the secondary forests and old-growth forests. The diversity of forest floor plants did not recover well after being clear-cut. This indicates that management of the subtropical forest should not only take timber-oriented tree species into account, but also the biodiversity in ground flora. The secondary forests were characterized by Castanopsis sieboldii and Schima wallichii, and the monopolization of C. sieboldii through secondary succession had a negative influence on species diversity. Distylium racemosum dominated at the late development stage and was considered a long-lived competing species that reduced the dominance of C. sieboldii and facilitated the co-occurrence of understorey species. Light-demanding pioneer tree species such as S. wallichii that regenerated after logging should be replaced by competitive effects of climax species, and thus relayed floristic change might increase species diversity along secondary succession.Nomenclature: Hatushima and Amano (1994).     

Loss of biodiversity and shifts in aboveground biomass drivers in tropical rainforests with different disturbance histories

Tropical forests account for more than half of the global carbon forest stock and much of the biological diversity on Earth. However, disturbances such as deforestation and forest degradation threaten the maintenance of these ecosystem services. This study aimed to understand how different disturbance histories affect the forest stand biomass, as well as species and functional diversity, and to what extent these differences can change the relationships between biomass and their drivers. We used data from forests with clear-cut and selectively logged disturbance histories, and from old-growth forests, situated in the Brazilian Atlantic forest. Forests with logging disturbances showed significant losses in their aboveground biomass compared to those of old-growth forests (50% loss in selectively logged forests and 80% loss in clear-cut forests). Interestingly, only clear-cut secondary forests showed differences in species and functional diversity, and were dominated by species with acquisitive trait values, commonly found early in succession. Shifts in stand biomass drivers were observed in selectively logged forests. The mass-ratio hypothesis (mainly through the functional trait of maximum height) was the most important biomass driver in clear-cut secondary and old-growth forests, whereas the importance of the niche complementarity hypothesis (through functional richness and dispersion) was higher in selectively logged forests. Our study highlights that disturbance histories can affect forest aboveground biomass and its drivers. Moreover, our results reinforce the need for conservation of intact forests but highlight the importance of including degraded forests in conservation mechanisms based in carbon stocks, as these forests retain high values of species and functional diversities that are crucial to biomass and consequently carbon stock acquisition.     

长白山落叶松和白桦-沼泽生态交错带群落演替规律研究

研究了长白山落叶松、白桦沼泽生态交错带群落演替规律,通过野外观测和建立斑块状态、林木蒸腾量与林木年龄的相关模型,利用相关模型定量地分析斑块和林木蒸腾量随林木年龄增长的动态变化过程,并分析了区域气候变化和群落演替的关系。探讨森林沼泽交错群落对湿地生境改造作用、湿地生境的中生化过程以及区域气候变暖对森林湿地演替的影响机制,揭示森林沼泽生态交错带群落的演替规律。结果表明,斑块宽度、高度、面积、体积随林木年龄增长均呈现三次式相关关系,林木蒸腾量随林木年龄增长呈现幂函数相关关系。落叶松、白桦沼泽交错群落经过60年左右时间发育,斑块将不断扩大,使地势平均升高0．405～0,590m;林木蒸腾量也不断增大,平均降低水位1．050～1．442m。森林湿地生境将演变为中生化的森林生境,同时,区域气候变暖与森林树种向湿地侵入存在密切关系,区域气候变暖将加快森林向湿地侵入进程,进而森林沼泽交错群落在相对较短的时间内(50～60年)将演替为森林群落。     

Persistent and pervasive compositional shifts of western boreal forest plots in Canada

Species compositional shifts have important consequences to biodiversity and ecosystem function and services to humanity. In boreal forests, compositional shifts from late‐successional conifers to early‐successional conifers and deciduous broadleaves have been postulated based on increased fire frequency associated with climate change truncating stand age‐dependent succession. However, little is known about how climate change has affected forest composition in the background between successive catastrophic fires in boreal forests. Using 1797 permanent sample plots from western boreal forests of Canada measured from 1958 to 2013, we show that after accounting for stand age‐dependent succession, the relative abundances of early‐successional deciduous broadleaves and early‐successional conifers have increased at the expense of late‐successional conifers with climate change. These background compositional shifts are persistent temporally, consistent across all forest stand ages and pervasive spatially across the region. Rising atmospheric CO₂ promoted early‐successional conifers and deciduous broadleaves, and warming increased early‐successional conifers at the expense of late‐successional conifers, but compositional shifts were not associated with climate moisture index. Our results emphasize the importance of climate change on background compositional shifts in the boreal forest and suggest further compositional shifts as rising CO₂ and warming will continue in the 21st century.     

中国东北森林生长演替模拟模型及其在全球变化研究中的应用

 NEWCOP模型是一个新的适于模拟东北森林的种类组成动态的林窗类计算机模拟模型,它通过模拟在每一个林分斑块上的每株树木的更新、生长和死亡的全过程来反映森林群落的中长期生长和演替动态。由于 NEWCOP模型是一个由气候变量驱动的生态系统模型,故可用于评价气候变化对东北森林生长和演替的影响。在东北大兴安岭、小兴安岭和长白山地区对NEWCOP模型进行了验证和校准。沿环境梯度对NEWCOP模型的数字模拟实验表明：它能准确地再现顶极森林中树种组成及其在东北地区的垂直分布规律和水平分布规律;能准确地再现大兴安岭、小兴安岭和长白山的主要类型森林的生长和演替规律;在一定的场合NEWCOP还可反映林分的径级结构;NEWCOP模型还具有对现有森林的跟踪模拟能力。应用NEWCOP模型评估了东北森林生态系统对可能气候变化的敏感性。在GFDL 2×CO2和GISS 2×CO2气候变化情景下,东北森林的种类组成将发生很大变化,落叶阔叶树将取代目前长白山、小兴安岭的红松(Pinus koraiensis)和大兴安岭的兴安落叶松(Larix gmelinii)成为东北森林主要树种,而针叶树将在地带性森林中占很小的比重,阔叶树中蒙古栎(Quercus mongolica)将是最重要的树种,它将成为小兴安岭和大兴安岭最主要树种;东北地区适于森林生长的区域将大幅度减少,这些变化主要发生在气候变化过渡期。东北森林对不同的气候变化情景有不同响应。但是,总的趋势是未来东北森林中落叶阔叶树的比重将大幅度增加。这些结论对在全球气候变化背景下,我国东北合理地选择造林树种和制定现有森林的保护经营策略具有一定参考价值。     

A role-type model (rope) and its application in assessing climate change impacts on forest landscapes

Gap-phase replacement is a general phenomenon found in forest ecosystems, worldwide. Different tree species can be expected to produce different sizes of gaps when they die. Species also vary in their regeneration success in gaps of different sizes. In this paper, the gap-phase interactions among tree species in a forest stand are simulated by a role-type stand model called ROPE. By incorporation of environmental effects on tree height, ROPE can simulate forest composition and stand leaf area under different climate conditions. The model was developed for forest ecosystems in northeastern China and was used to simulate the forest landscape structures under current climate conditions and under four climate change scenarios for greenhouse gas related warming. These scenarios were obtained from general circulation models developed by different atmospheric research centers. Korean pinebroadleaf mixed forest and larch forest are the major stand types in the study area under present conditions. Under the four climate change scenarios, Korean pine-broadleaf mixed forest would be expected to occur only on the higher parts of large mountains. Larch forest only would be found north of the study area. Broadleaf forest would become the dominant vegetation over the study area. Use of the Kappa statistic to test for similarity in spatial maps, indicates that each climate change scenario would result in a significant change of forest distributions.Supported by The United States National Science Foundation Grant BSR-8702333 to University of Virginia.     

Carbon dynamics in the future forest: the importance of long‐term successional legacy and climate–fire interactions

Understanding how climate change may influence forest carbon (C) budgets requires knowledge of forest growth relationships with regional climate, long‐term forest succession, and past and future disturbances, such as wildfires and timber harvesting events. We used a landscape‐scale model of forest succession, wildfire, and C dynamics (LANDIS‐II) to evaluate the effects of a changing climate (A2 and B1 IPCC emissions; Geophysical Fluid Dynamics Laboratory General Circulation Models) on total forest C, tree species composition, and wildfire dynamics in the Lake Tahoe Basin, California, and Nevada. The independent effects of temperature and precipitation were assessed within and among climate models. Results highlight the importance of modeling forest succession and stand development processes at the landscape scale for understanding the C cycle. Due primarily to landscape legacy effects of historic logging of the Comstock Era in the late 1880s, C sequestration may continue throughout the current century, and the forest will remain a C sink (Net Ecosystem Carbon Balance > 0), regardless of climate regime. Climate change caused increases in temperatures limited simulated C sequestration potential because of augmented fire activity and reduced establishment ability of subalpine and upper montane trees. Higher temperatures influenced forest response more than reduced precipitation. As the forest reached its potential steady state, the forest could become C neutral or a C source, and climate change could accelerate this transition. The future of forest ecosystem C cycling in many forested systems worldwide may depend more on major disturbances and landscape legacies related to land use than on projected climate change alone.