川西亚高山不同森林类型土壤酶活性对短期凋落物输入量变化的响应

凋落物输入是生态系统物质循环和能量流动的重要环节,在维持亚高山森林的"自肥"机制及生态系统结构和功能等方面具有不可替代的作用.为进一步了解川西亚高山森林土壤物质循环过程,以该地区典型森林为对象,通过进行凋落物输入控制试验,研究3种森林类型(阔叶林、针阔混交林和针叶林)不同时期(添加时间)凋落物输入变化对土壤碳(C)、氮(N)和磷(P)分解相关的酶活性及其化学计量比的影响.结果显示:3种森林类型中凋落物输入对土壤酶活性的影响不显著,而不同林型和凋落物输入时间则显著影响了土壤酶活性.凋落物处理1.5年时期,在凋落物输入处理中,阔叶林的β-葡萄糖苷酶和纤维二糖水解酶的酶活性显著高于针阔混交林(2.69和2.73倍)和针叶林(1.87和1.47倍);而在凋落物去除处理中,针叶林中的酸性磷酸酶活性则显著大于阔叶林(1.72倍)与针阔混交林(1.66倍).相关性分析表明,土壤含水量以及C、N含量是影响酸性磷酸酶、β-葡萄糖苷酶和纤维二糖水解酶变化的主要因素,而多酚氧化酶和过氧化物酶主要受到土壤pH以及土壤硝态氮含量的影响.根据生态酶化学计量理论,本研究的土壤酶化学计量碳氮比(C:NEEA)均低于全球平均值,而土壤酶化学计量碳磷比(C:PEEA)和土壤酶化学计量氮磷比(N:PEEA)均高于全球平均值,表明该区域N转化酶活性较高,处于相对N限制的区域.本研究表明在养分循环较慢的川西亚高山地区,短期凋落物的输入对土壤酶活性的影响较为缓慢,但不同凋落物组成(林型)对土壤酶活性的影响不同,关于土壤酶活性对于凋落物输入的响应还有待长期研究.(图4表3参49)     

亚热带森林凋落物层土壤酶活性的季节动态

凋落物分解是森林生态系统养分循环中至关重要的过程。凋落物的分解与凋落物中的分解酶的活性直接相关。本研究调查了亚热带常绿阔叶林与针叶林中与土壤碳氮元素循环有关的β-糖苷酶(β-glucosidase)、内切纤维素酶(endocellulase)和几丁质酶(chitobiase)活性的季节变化规律。结果表明:在两个群落中,3种土壤酶活性与温度之间都有一定相关性,最高值均出现在温度较高的七月份;阔叶林中三种酶的活性在各个季节中大小顺序都为未分解凋落物层(L)>半分解层(F)>腐殖质层(H),而针叶林中则是半分解层(F)>未分解凋落物层(L)>腐殖质层(H);在每个取样时间点β-糖苷酶和几丁质酶的活性最高值都在阔叶林L层,显著高于针叶林L层,而内切纤维素酶的活性最高值是在针叶林H层。两林型下酶活性动态的差异,可能是导致两林型下凋落物层残存量差别的一个重要原因。     

凋落物处理对森林地表CO2通量的影响及其调控机理

全球变化和森林演替可以导致森林地表凋落物数量和质量的变化,从而对森林地表 CO2通量产生影响。本实验对亚热带不同演替阶段的3种,即马尾松林（前期）、混交林（中期）和季风林（后期）进行地表凋落物去除、加倍与置换处理,利用静态箱气相色谱法测定地表CO2通量,并同步测定气温、土壤温度和湿度,分析凋落物质量和数量变化对森林地表CO2通量的影响及其调控机理。结果表明,（1）去除凋落物处理显著降低了不同演替阶段的3种森林地表CO2通量,而加倍凋落物处理可以增加森林地表CO2通量,但不同演替阶段增加的幅度不同,依次为：季风林＞马尾松林＞混交林。（2）置换凋落物对不同演替阶段的森林地表 CO2通量的影响不同,在演替后期的季风林中,置换混交林和马尾松林凋落物处理均增加地表CO2通量;在演替中期的混交林中,置换季风林和马尾松林凋落物均降低地表CO2通量。在演替前期的马尾松林中,置换季风林凋落物增加地表CO2通量,而置换混交林凋落物降低了地表CO2通量（3）结合测定的土壤温度和水分数据分析得出,凋落物处理引起森林地表 CO2通量的变化是通过处理凋落物质量和数量后改变森林地表水热条件来实现的。（4）3个林型的各种处理,地表 CO2通量与土壤温度均呈显著的指数相关关系,但不同处理不同地改变了森林地表土壤 CO2通量对温度的敏感性,即Q10值。     

珠江三角洲四种森林类型土壤CO2通量特征研究

采用开路式土壤CO2通量测量系统Li-8100&Li-8150对珠江三角洲地区尾叶桉(Eucalyptus urophylla)人工林、乡土树种恢复林、针阔叶混交林和常绿阔叶林4种林型的土壤CO2通量进行了观测。结果表明:4种森林类型年均土壤CO2通量为尾叶桉人工林(3.35μmol.m-2.s-1)>针阔叶混交林(2.66μmol.m-2.s-1)>乡土树种恢复林(2.09μmol.m-2.s-1)>常绿阔叶林(1.86μmol.m-2.s-1);旱季土壤CO2通量明显小于雨季。前3种森林类型凋落物呼吸处理表明,旱季对照组土壤CO2通量均小于相应的去除凋落物组、雨季则相反,全年的对比结果显示,3种森林类型的凋落物呼吸贡献分别达到1.3%、7.1%和10.8%。土壤CO2通量与10 cm土壤温度呈显著指数相关,且土壤CO2通量温度敏感指数表现为针阔叶混交林Q10最大(3.49),尾叶桉人工林Q10最小(1.95)。     

洪涝灾害干扰下受损自然恢复林地土壤基本性状及分形维数特征

选取重大洪涝灾害干扰下受损自然恢复3种不同林地(毛竹林、杉木林、次生阔叶林)为研究对象,以未受损林地为对照,测定不同林型土壤基本性状指标(包括土壤颗粒组成在内的物理性质、主要养分含量),并运用分形理论计算了分形维数D值,探讨分形维数与土壤基本性状的相关关系.结果表明:(1)3种不同林型土壤均以粉粒含量占比最大,分形维数在2.58-2.70之间,0-10 cm土层分形维数表现为毛竹林杉木林次生阔叶林,受损自然恢复林地未受损林地,其中次生阔叶林的受损自然恢复林地与未受损林地差异显著.(2)毛竹林与次生阔叶林土壤容重表现为受损自然恢复林地显著大于未受损林地,土壤含水量、毛管持水量、非毛管孔隙度与总孔隙度则相反,受损自然恢复与未受损杉木林间土壤物理性质的差异较小;各林型土壤养分含量随土层深度的增加而降低,且受损自然恢复林地显著低于未受损林地,总体恢复状况表现为杉木林次生阔叶林毛竹林.(3)土壤分形维数与土壤黏粒含量、土壤容重存在显著正相关关系,与有机质、全氮、土壤含水量、毛管持水量、非毛管孔隙度及总毛管孔隙度存在显著负相关关系.因此,分形维数能够客观地表征土壤的结构特征以及土壤养分肥力特征;受损恢复林地土壤条件还未达到未受损林地的水平,对恢复状况较差的毛竹林,可以适当地进行人工植树造林,优化群落结构,进而改善土壤条件,促进灾害干扰下受损植被的恢复进程.     

“非正常”凋落物对冰雪灾后南岭森林土壤有机碳的影响

2008年初,一场百年罕见的冰雪灾害袭击了我国南方地区,对南方19个省（区）的林区,相当中国森林面积的13%（1.86×107 hm2）的森林植被遭受整体性、毁灭性破坏,导致的大量“非正常”凋落物必将对森林土壤碳循环产生深远影响。本研究以广东乐昌杨东山十二度水省级自然保护区不同海拔梯度上受灾的常绿阔叶混交林3种森林群落为研究对象,采用去除冰雪灾害导致的“非正常”凋落物与受损林地进行对照试验,对冰雪灾害所导致“非正常”凋落物对土壤碳的影响进行了研究。研究结果表明：灾后3种森林群落中不同深度土壤的有机碳质量分数和储量持续增加,同一深度土壤有机碳质量分数和碳储量在不同年份之间差异显著。直至2011年“非正常”凋落物分解完毕时,10~50 cm的土壤有机碳质量分数与上一年相比有减少趋势;0~10 cm的土壤有机碳质量分数稍比2010年高,但变化差异不显著(p=0.36),说明在“非正常”凋落物分解结束后土壤有机碳质量分数有减小的趋势,致使土壤碳储量下降。去除“非正常”凋落物样地与对照样地相比,各土壤深度的土壤有机碳质量分数明显下降,年平均下降百分比例变化范围为12.14%~55.34%,0~10 cm和10~30 cm土壤的有机碳质量分数下降变化波动幅度要比30~50 cm大;不同深度土壤有机碳质量分数与凋落物有机碳失质量间具有显著的线性相关性。可见,冰雪灾害导致的“非正常”凋落物对土壤有机碳质量分数和储量都有十分显著的影响,“非正常”凋落物的分解输入能显著提高土壤有机碳质量分数和储量。     

氮沉降下鼎湖山森林凋落物分解及与土壤动物的关系

研究了南亚热带3种森林生态系统凋落物在N沉降下的分解动态及其与土壤动物群落的关系。选取季风常绿阔叶林、针阔混交林和马尾松林建立野外模拟N沉降样地,实施四个处理组,对照(Control)、低氮(50kg·hm-2·a-1,LowN)、中氮(100kg·hm-2·a-1,MediujmN)和高氮处理(150kg·hm-2·a-1,HighN),利用凋落物网袋法,在18个月的时间内调查分析了凋落物分解过程及其中的土壤动物密度特征。研究结果表明,植被演替阶段对凋落物的分解速度存在影响,季风林凋落物降解速度显著性快于混交林和针叶林(P<0.05);18个月后,季风林各处理地凋落物残留率为0.05、0.14、0.13和0.17,混交林为0.64、0.56和0.62,针叶林为0.66、0.63和0.62。N沉降增加对凋落物分解存在一定影响。且这种影响与植被类型之间存在明显的交互作用。N沉降处理对季风林凋落物分解表现出了一定的抑制作用,而且这种差异随时间推移愈益明显,但在混交林和针叶林内,试验后期凋落物分解受到了N沉降处理的促进作用。在试验后期,尤其是12个月后,凋落物网袋土壤动物密度在不同林地和不同水平N处理下体现了差异化发展趋势。在季风林内,N处理地土壤动物密度受到了明显的抑制;在混交林和针叶林内,低N样地动物密度显示了相比对照样地的明显优势,但在较高强度的中N处理地无论在凋落物的降解速率还是在动物密度上都与对照样地没有明显差别。文章认为,N沉降处理所产生的影响可能受环境N饱和程度的调控。文章还提出,在凋落物分解进程中,土壤动物群落具有“后期进入”特征,这对于进一步准确分析森林凋落物分解进程及土壤动物的贡献有重要意义。     

四川盆地西缘峨眉含笑-喜树混交林凋落物量及碳氮磷动态特征

为认识四川盆地西缘亚热带典型阔叶混交林的凋落物产量模式与养分动态特征,通过直接收集法收集凋落物,对四川盆地西缘乡土珍贵树种峨眉含笑-喜树混交林凋落物产量、碳氮磷含量及归还量月动态进行了为期1年(2016)的观测和分析.结果显示:混交林中叶的年凋落物总量为2 853.36 kg/hm~2,其中含笑1 644.82 kg/hm~2,喜树1208.54 kg/hm~2.两种林木凋落叶产量季节动态明显,含笑凋落叶量最大值在出现4月(476.03 kg/hm~2),最小值出现在9月(43.73 kg/hm~2);而喜树最大值和最小值分别出现在11月(534.41 kg/hm~2)和6月(21.58 kg/hm~2).含笑和喜树凋落叶中碳氮磷含量在夏季相对较高.含笑凋落叶碳氮磷归还量高峰均在4月和11月;喜树凋落叶碳氮磷归还高峰均在11月.混交林凋落叶的碳氮磷年总归还量分别为1 186.11、38.78、1.76 kg/hm~2.总之,该区域混交林凋落物产量月动态模式主要受控于林木生物学特性,且凋落物碳氮磷含量和归还量存在明显季节性变化;结果可为区域生态系统相似混交林的保护和恢复提供理论依据.(图5表1参29)     

豫南山区不同群落类型近地表层持水特性

为了分析不同植物群落在不同生长阶段近地表层的持水能力及其差异特征,该文通过选择豫南山区不同群落不同生长阶段的50个典型样地,对近地表层的地上草和枯落物的有关持水能力指标进行测定分析。结果表明：地上草生物量呈随林龄的增大而减少的趋势,与其持水量之间呈极显著正相关关系（P〈0.01）,其拦蓄能力变化趋势为：草丛〉灌丛〉针叶林（20 a）〉针叶林（45 a）〉针阔混交林（20 a）〉针阔混交林（30 a）〉阔叶林（10 a）〉针阔混交林（50 a）〉阔叶林（20 a）〉阔叶林（30 a）;枯落物最大持水量、有效拦蓄量与现存量间呈正相关关系,其中最大持水量变化趋势为：灌丛〉阔叶林（20 a）〉阔叶林（30 a）〉针阔混交林（30 a）〉针阔混交林（20 a）〉针阔混交林（50 a）〉针叶林（20 a）〉阔叶林（10 a）〉针叶林（45 a）〉草丛。该地区不同群落类型近地表层总持水能力变化趋势为：灌丛〉针叶林〉阔叶林〉针阔混交林〉草丛,这说明应当加大对乔木林分林下植被的保护,以利更好的水土保持效果。     

震区典型受损区生态恢复过程中的土壤恢复率与空间异质性

在我国西南强地震影响区生态恢复重建的背景下,探明不同气候区不同恢复条件下的土壤有机碳(SOC)、全氮(TN)和全磷(TP)的恢复率以及空间异质性及其演变规律,对准确认识生态恢复作用下灾害干扰区的土壤恢复动态变化具有重要意义.选取汶川地震灾区干旱河谷气候区和亚热带季风气候区的受损治理区为研究样地,以邻近的未受损区为对照,分析地震后恢复期受损治理区土壤SOC、TN、TP的恢复率以及空间异质性的分布规律.结果表明,两种气候区内受损治理区SOC、TN、TP的含量整体上显著低于未受损区,说明地震后受损治理区的养分状况尚未恢复至震前水平.养分恢复率表现为亚热带季风气候区TN(53%-58%)、TP(51%-58%)高于干旱河谷季风气候区TN(32%-36%)、TP(41%-49%),SOC的平均恢复率在两个气候区表现基本一致,亚热带季风气候区具有更高的养分恢复率.干旱河谷气候区受损治理区和未受损区的养分变异系数均高于亚热带季风气候区,说明干旱河谷气候区土壤结构稳定性较差,受灾害破坏更为严重,土壤养分的空间异质性较大,发生水土流失及次生灾害的可能性更大.干旱河谷气候区受损治理区的C:N值大于未受损区,而亚热带季风气候区则相反.上述研究表明灾区土壤养分结构受到严重破坏,而气候可能是影响土壤恢复的主导因子,结果可为灾区生态恢复进程提供理论依据.(图2表4参38)     

The distribution of lianas and their change in abundance in temperate forests over the past 45 years

Lianas (woody vines) are an important and dynamic component of many forests throughout the world, and increases in CO2, mean winter temperature, and forest fragmentation may promote their growth and proliferation in temperate forests. In this study, we used a 45-year data set to test the hypothesis that lianas have increased in abundance and basal area in the interiors of 14 deciduous temperate forests in Wisconsin (USA) since 1959. We also censused woody plants along a gradient from the forest edge to the interior in seven of these forests to test the hypothesis that the abundance of lianas declines significantly with increasing distance from the forest edge. We found that lianas did not increase in abundance within the interiors of temperate forests in Wisconsin over the last 45 years. However, relative and absolute liana abundance decreased sharply with increasing distance from forest edges. Our findings suggest that forest fragmentation, not climate change, may be increasing the abundance of lianas in northern deciduous temperate forests, and that lianas may further increase in abundance if the severity of forest fragmentation intensifies.     

Biogeochemical model (BGC-ES) and its basin-level application for evaluating ecosystem services under forest management practices

It is important for humans to live in harmony with ecosystems. Evaluation of ecosystem services (ES) may be helpful in achieving this objective. In Japan, forest ecosystems need to be re-evaluated to prevent their degradation due to lack of forest management.In order to evaluate the effects of forest management on forest ES, we developed a process-based biogeochemical model to estimate water, carbon, and nitrogen cycles in forest ecosystems (BGC-ES). This model consists of four submodels: biomass, water cycle, carbon-nitrogen (CN) cycles, and forest management. The biomass submodel can calculate growth of forest biomass under forest managements.Several parameters of the model were calibrated using data from observations of evapotranspiration flux and quality of stream flow in forests. The model results were compared with observations of runoff water from a dam catchment site and with carbon flux observations.Our model was coupled with a basin-level GIS database of forests. Evaluations under various forest management scenarios were carried out for forests in a basin contained in the Ise Bay basin (Chubu region, Japan), where plantations (artificial forests) seemed to have degraded from poor forest management.Comparing our simulation results with those of forests without management in the basin, we found that the amounts of absorbed carbon and runoff were larger in managed forests. In addition, the volume of harvested timber was larger and its quality (diameter) was better in managed forests. Changes of ES within the various scenarios were estimated for their economic value and were compared with the cost of forest management.     

Rethinking Tropical Forest Conservation: Perils in Parks

Abstract: According to some conservationists, large, pristine, uninhabited parks are the defining criterion of success in conserving tropical forests. They argue that human residents in tropical forests inevitably deplete populations of large animals through hunting, which triggers a chain reaction of ecological events that greatly diminish the conservation value of these forests. Hence, they believe that removal of people from tropical forests is an essential step in the creation of successful parks and in the conservation of nature in the tropics. This approach can lead to undesirable consequences, however. Forest residents—and rural people generally—are potent political actors in tropical forest regions and an essential component of the environmental political constituencies that are necessary for the long-term conservation of tropical forests. In Amazonia and elsewhere, rural people are defending far bigger areas of tropical forest from unfettered deforestation and logging than are parks, thereby conserving the ecological services provided by these forests and the majority of their component plant and animal species. Moreover, the data are too sparse to judge the effects of forest peoples on populations of large forest animals. The establishment of pristine, tropical forest parks is an important conservation goal, but the exclusive pursuit of this goal undermines the broader objectives of conservation when it identifies forest residents and other rural people as the enemies of nature.     

The Potential for Species Conservation in Tropical Secondary Forests

Abstract: In the wake of widespread loss of old‐growth forests throughout the tropics, secondary forests will likely play a growing role in the conservation of forest biodiversity. We considered a complex hierarchy of factors that interact in space and time to determine the conservation potential of tropical secondary forests. Beyond the characteristics of local forest patches, spatial and temporal landscape dynamics influence the establishment, species composition, and persistence of secondary forests. Prospects for conservation of old‐growth species in secondary forests are maximized in regions where the ratio of secondary to old‐growth forest area is relatively low, older secondary forests have persisted, anthropogenic disturbance after abandonment is relatively low, seed‐dispersing fauna are present, and old‐growth forests are close to abandoned sites. The conservation value of a secondary forest is expected to increase over time, as species arriving from remaining old‐growth forest patches accumulate. Many studies are poorly replicated, which limits robust assessments of the number and abundance of old‐growth species present in secondary forests. Older secondary forests are not often studied and few long‐term studies are conducted in secondary forests. Available data indicate that both old‐growth and second‐growth forests are important to the persistence of forest species in tropical, human‐modified landscapes.     

北京西山地区不同林分健康状况比较研究

以不同树种林分健康状况比较研究为切入点,以北京西山地区同一时期的油松×侧柏混交林、油松（Pinus tabulaeformis）林、侧柏（Platycladus orientalis）林和栓皮栎（Quercus variabis）林为研究对象。通过构建林分健康评价指标体系,计算林分综合健康指数,分别对不同林分的健康状况进行了分析和比较,探讨不同林分开展森林健康经营的关键环节,同时也从森林健康的角度说明造林树种选择的重要性。研究结果表明：各林分综合健康指数都为正值但数值都不高,这表明目前各林分都处于健康状态,但对外界扰动反应较为敏感,按健康状况排序：油松×侧柏林0．234〉栓皮栎林0．186〉油松林0．145〉侧柏林0．128;从单个指标看,各林分中都有负值指标出现,由此揭示,对负值指标的调整和增加正向指标的指标值是森林健康经营的关键。     

Biodiversity Differences between Managed and Unmanaged Forests: Meta-Analysis of Species Richness in Europe

Abstract: Past and present pressures on forest resources have led to a drastic decrease in the surface area of unmanaged forests in Europe. Changes in forest structure, composition, and dynamics inevitably lead to changes in the biodiversity of forest‐dwelling species. The possible biodiversity gains and losses due to forest management (i.e., anthropogenic pressures related to direct forest resource use), however, have never been assessed at a pan‐European scale. We used meta‐analysis to review 49 published papers containing 120 individual comparisons of species richness between unmanaged and managed forests throughout Europe. We explored the response of different taxonomic groups and the variability of their response with respect to time since abandonment and intensity of forest management. Species richness was slightly higher in unmanaged than in managed forests. Species dependent on forest cover continuity, deadwood, and large trees (bryophytes, lichens, fungi, saproxylic beetles) and carabids were negatively affected by forest management. In contrast, vascular plant species were favored. The response for birds was heterogeneous and probably depended more on factors such as landscape patterns. The global difference in species richness between unmanaged and managed forests increased with time since abandonment and indicated a gradual recovery of biodiversity. Clearcut forests in which the composition of tree species changed had the strongest effect on species richness, but the effects of different types of management on taxa could not be assessed in a robust way because of low numbers of replications in the management‐intensity classes. Our results show that some taxa are more affected by forestry than others, but there is a need for research into poorly studied species groups in Europe and in particular locations. Our meta‐analysis supports the need for a coordinated European research network to study and monitor the biodiversity of different taxa in managed and unmanaged forests.     

珠江三角洲森林的生物量和生产力研究

利用森林资源清查资料和经过实地校正的相关森林生物量和生产力估算方程,对珠江三角洲森林植被的生物量和生产力进行了研究。结果表明,珠江三角洲森林的生物量为132 404 963 t,总净生产量为26 273 769 t.a-1。区域森林生物量主要分布在珠江三角洲的外围,其中,马尾松林和常绿阔叶林的生物量占区域森林总生物量的52.18%;生态公益林的生物量只到达用材林的48.68%;中幼龄林生物量所占比例很大,总体质量不高,但如果现有森林得到更好地保护和管理,珠江三角洲地区的森林会有较大的发展潜力,并在维护区域生态环境上起着主导作用。     

Ecological consequences of forest elephant declines for Afrotropical forests

Poaching is rapidly extirpating African forest elephants (Loxodonta cyclotis) from most of their historical range, leaving vast areas of elephant‐free tropical forest. Elephants are ecological engineers that create and maintain forest habitat; thus, their loss will have large consequences for the composition and structure of Afrotropical forests. Through a comprehensive literature review, we evaluated the roles of forest elephants in seed dispersal, nutrient recycling, and herbivory and physical damage to predict the cascading ecological effects of their population declines. Loss of seed dispersal by elephants will favor tree species dispersed abiotically and by smaller dispersal agents, and tree species composition will depend on the downstream effects of changes in elephant nutrient cycling and browsing. Loss of trampling and herbivory of seedlings and saplings will result in high tree density with release from browsing pressures. Diminished seed dispersal by elephants and high stem density are likely to reduce the recruitment of large trees and thus increase homogeneity of forest structure and decrease carbon stocks. The loss of ecological services by forest elephants likely means Central African forests will be more like Neotropical forests, from which megafauna were extirpated thousands of years ago. Without intervention, as much as 96% of Central African forests will have modified species composition and structure as elephants are compressed into remaining protected areas. Stopping elephant poaching is an urgent first step to mitigating these effects, but long‐term conservation will require land‐use planning that incorporates elephant habitat into forested landscapes that are being rapidly transformed by industrial agriculture and logging.     

Two‐Stage Recovery of Amphibian Assemblages Following Selective Logging of Tropical Forests

There is a lack of quantitative information on the effectiveness of selective‐logging practices in ameliorating effects of logging on faunal communities. We conducted a large‐scale replicated field study in 3 selectively logged moist semideciduous forests in West Africa at varying times after timber extraction to assess post logging effects on amphibian assemblages. Specifically, we assessed whether the diversity, abundance, and assemblage composition of amphibians changed over time for forest‐dependent species and those tolerant of forest disturbance. In 2009, we sampled amphibians in 3 forests (total of 48 study plots, each 2 ha) in southwestern Ghana. In each forest, we established plots in undisturbed forest, recently logged forest, and forest logged 10 and 20 years previously. Logging intensity was constant across sites with 3 trees/ha removed. Recently logged forests supported substantially more species than unlogged forests. This was due to an influx of disturbance‐tolerant species after logging. Simultaneously Simpson's index decreased, with increased in dominance of a few species. As time since logging increased richness of disturbance‐tolerant species decreased until 10 years after logging when their composition was indistinguishable from unlogged forests. Simpson's index increased with time since logging and was indistinguishable from unlogged forest 20 years after logging. Forest specialists decreased after logging and recovered slowly. However, after 20 years amphibian assemblages had returned to a state indistinguishable from that of undisturbed forest in both abundance and composition. These results demonstrate that even with low‐intensity logging (≤3 trees/ha) a minimum 20‐year rotation of logging is required for effective conservation of amphibian assemblages in moist semideciduous forests. Furthermore, remnant patches of intact forests retained in the landscape and the presence of permanent brooks may aid in the effective recovery of amphibian assemblages. Recuperación de Ensambles de Anfibios en Dos Etapas Después de la Tala Selectiva de Bosques Tropicales     

The progress and challenges in sustainable forestry development in China

Forestry development in China has undergone a series of reforms over the past six decades. This article examines temporal changes in forest resources and policies, the current status of forestry, and future challenges toward sustainable forest management in China. Excessive logging in the 1950s to 1980s badly damaged the nation’s forests, but the adoption of enlightened forest policies in the late 1990s has led to increases in China’s total forest area and growing stock. Forest degradation was ecologically and economically costly, and rehabilitation processes have become increasingly more expensive. The low quality and young age of forest resources, loss of natural forests, and more difficulties in afforestation and reforestation pose severe challenges for China’s sustainable forestry. It is critically important for China to enhance forest productivity through intensive management, strengthen enforcement, and educational programs for protecting and restoring natural forests, narrow the gap between domestic timber supply and rapidly expanding consumption, improve coordinating networks for management, finance, and technology transfer, and accelerate efforts to clarify and stabilize tenure arrangements for non-state forests. China’s experience and lessons in forestry may be helpful for other developing countries that are seeking to achieve the goal of sustainable forest management.