Hydrological classification in mangrove areas: A case study in Can Gio,Vietnam

The common hydrological classification for mangroves developed by Watson [Watson, J.G., 1928. Mangrove forests of the Malay Peninsula. Malayan Forest Records No. 6. Forest Department, Federated Malay States, Kuala Lumpur] is not sufficient in mangrove areas with an irregular tidal regime and elevation, such as Can Gio in Vietnam. Incorporating more detailed hydrological information in the Watson classification gave promising results for the measuring sites in Can Gio, but should be tested in other mangrove areas.     

Local Mangrove Planting in the Philippines: Are Fisherfolk and Fishpond Owners Effective Restorationists?

Local fisherfolk and fishpond owners have been practicing “restoration” of mangrove forests in some parts of the Philippines for decades, well before governments and non‐government organizations began to promote the activity as a conservation tool. This paper examines ecological characteristics of these mangrove plantations and compares them to natural mangroves in the same areas. Mangrove planters were interviewed and plantation and natural mangrove forests were surveyed to measure forest structure, composition and regeneration. Compared with natural forests, mangrove plantations were characterized by high densities of small stems, shorter and narrower canopies, and fewer species. For both economic and ecological reasons, the vast majority of people dispersed and planted only Rhizophora mucronata/stylosa and, furthermore, they often thinned other species out of planted areas. There was remarkably little subsequent recruitment of other, nonplanted mangrove species into plantations up to 50 and 60 years of age. This pattern held across a diversity of sites, including plantations that had not been selectively cut or weeded. Important ecological and economic benefits result from local mangrove planting, but catalyzing diverse forest regeneration—at least in the short to medium term—is not one of them. The lesson: if you want to restore diverse mangrove forests, you have to plant diverse mangrove forests.     

Forest Transition in Xishuangbanna,Yunnan

Forest transition is a process of overall forest cover from net loss to net gain over time. Forest transition especially the process after turning point from deforestation to reforestation has inspired lots of researches for its potential to improve environmental services. China has undergone forest transition since the 1980s. However, in tropical China, deforestation was still existed, while the overall forest cover increased greatly. To investigate this issue, we conducted this research by classifying overall forest into natural forest and plantation in Xishuangbanna, which has undergone forest transition and deforestation and overall forest cover increasing. We found that natural forest continues decreasing while overall forest cover increasing and plantation expansion in forest transition. The forest transition in Xishuangbanna was found to be a tree cover transition, which was mainly contributed by large plantation expansion. In Xishuangbanna, deforestation is still undergoing after its overall forest cover transition occurred in 1988. The general overall forest definition used by forest transition will not be able to recognize deforestation when natural forests are displaced by plantations because the overall forest cover remains unchanged or even increasing. We therefore recommended to classify forest types in forest transition researches.     

Gap creation and regenerative processes driving diversity and structure of mangrove ecosystems

Turnover within both mangrove and terrestrial forests is driven by standdevelopment in conjunction with factors influencing tree death andreplacement at various temporal and spatial scales. Development interrestrial forests appears comparable with that in mangroves but turnoverseems to differ considerably between these broad forest types. The mostimportant difference is in the character of small forest gaps. Gaps arecommon in terrestrial forests but those in mangroves rarely involve falls oflarge older trees in the first instance. Instead, mangrove trees usually diestanding in small clusters of mixed age cohorts. Identifying a common causefor gap creation in mangroves might be important towards understandingwhat drives forest turnover but there is a greater need to quantify thisprocess. Small-scale disturbance in mangrove forests is poorly quantified butpreliminary evidence implies that its' importance may have been greatlyunder-estimated. Based on available observations, a conceptual model ofmangrove forest development and gap regeneration is proposed. The modelhelps explain the peculiar characteristics and structure of mangrove forestsand how these forests might respond to changing environmental conditionsand disturbance at various landscape scales.     

云南西双版纳地区森林转型特征(英文)

森林转型是指森林覆盖率由净减少到净增加的过程。中国森林早在20世纪80年代就进入了转型期,然而,中国热带地区的总森林覆盖率虽呈增长趋势,但依旧存在着天然林大量被毁的现象。鉴于天然林对森林生态系统功能的重要作用,本研究通过加入森林类型分类的内容,以西双版纳为例探讨其森林转型的真实特征。结果表明:森林转型理论单纯以"总森林"覆盖率为研究对象,忽视了其他森林类型的动态变化,甚至掩盖了"天然林"的真实动态变化。西双版纳的森林转型主要是人工种植林的扩张所致,只是树木数量统计上的转型。事实上,自1988年以来,西双版纳的天然林一直在锐减。所以建议未来关于森林转型的研究应将"森林"区分成不同的森林类型加以研究。     

人工林与天然林破碎化过程差异对比——以美国华盛顿州和密西西比州为例

森林损失和破碎化一直是国际社会普遍关注的重大环境问题之一。根据Forman景观变化包括穿孔、分割、破碎化、收缩和消失5种空间过程的理论,利用ArcGIS Modeler建立森林破碎化过程模型用以明确描述森林景观破碎化的空间过程和生态进程。基于NLCD2001、2006、2011 3期数据,以美国华盛顿州和密西西比州为研究区,利用森林破碎化过程模型,将森林损失斑块分为4种破碎化过程(分割类型因其线状特征被归入破碎化类型),对比分析天然林和人工林的破碎化过程在时空上的差异性。研究表明天然林破碎化斑块多分布于城市/森林、耕地/森林、以及灌木/森林的交界处,而人工林破碎化斑块分布格局较为零散;天然林中破碎化斑块和收缩斑块大多发生在上阶段收缩、破碎化以及穿孔斑块的边缘,而人工林中4种空间过程的承接关系不像天然林那么明显,但两者整体上都呈现相似的"收缩-消失-穿孔/破碎化"变化规律,主要表现为收缩类型占主导然后慢慢消退,穿孔和破碎化逐渐增多占据新的主导。     

Local Management of Mangrove Forests in the Philippines: Successful Conservation or Efficient Resource Exploitation?

Recent environmental narratives suggest that local people are effective stewards of forest resources. Local restoration and management of mangrove forests, in particular, are now widely advocated as a solution to achieve both economic and environmental conservation goals. This paper presents findings from a study of 2 coastal sites in the Philippines that are renowned and often showcased as success stories in community-based, mangrove reforestation and management. These cases are especially intriguing because local tree planting and management emerged in both areas long before governments and nongovernment organizations began to promote such activities. These management systems are a successful economic innovation in that planted mangroves protect homes and fish pond dykes from wave and wind damage, and the production of high-value construction wood is dramatically enhanced through intensive plantation management. Mangrove plantations are an efficient alternative to harvesting from unplanted, natural mangroves and their spread may reduce harvesting pressures on existing forests. However, mangrove plantations are structurally and compositionaly very different from unplanted forests, a finding of particular concern given that such plantations are increasingly encroaching into and replacing natural forests. Furthermore, planted forests are not typically viewed by planters in terms of their environmental conservation values and are frequently cut and cleared to make space for alternative uses, especially fish farming and residential settlement. The suggestion that these local mangrove management systems are successful for conservation thus needs to be qualified.     

Interactive effects of flooding and forest gap formation on tree composition and abundance in the Peruvian Amazon

In order to better understand how flooding and gap formation affect Amazonian rainforests, I set up plots both in three major forest types that differed by flooding duration (referred to here as dry, wet, very wet) and in their respective gaps. Sampling of those plots after 4 years of regeneration showed: (1) common species exist between wet forests and their gaps and between wet and very wet gaps, (2) tree richness is maximum in dry forest and minimum in very wet gaps except in the wet gaps that show the second highest number of species, (3) there were less stems in gaps compared to forests and less stems in forests as flooding increased, except again in the wet gaps, and (4) dominance-diversity curves have more dominance by single species in the dry gap plots compared to other gaps and in dry forest compared to other forests. In general while some aspects of structure such as tree stem density is largely determined by tree-fall gap dynamics, tree composition is determined by flooding regime. Finally a jump in tree richness in wet forests and wet gaps compared to other plots suggests a “mass effects” hypothesis where species from dry and very wet forest and gaps have overlapping ranges in the wet forest and gap. This effect may help explain the high species diversity seen in this part of the Amazon.     

Phenomenological models of the forest plantations growth

Phenomenological models of the forest plantations growth are analyzed. Those derived from the Verhulst's model are shown to fail describing qualitative effects reflecting tree growth, phytomass withdrawals, and plantation restoration. The method of phase portraits is used for exploration of the forest ecosystem dynamics, which allows to describe regulatory mechanisms of the growth processes, regulation delay, and feedback types. A bistable phenomenological model is suggested herewith to characterize dynamic processes in the forest ecosystems. Principal patterns of formation of the forest plantations at different stages of the forest generation processes are considered on the basis of that model, and ecological effects responsible for the plantation dynamics are revealed.     

Simulation of moss and tree dynamics in the boreal forests of interior Alaska

We used a simulation model of forest dynamics to examine the ecological significance of the complex interactions among site conditions, tree growth, and the development of a thick forest floor moss layer found in many boreal forests. To examine the effect of site conditions on moss growth and forest dynamics, we simulated the dynamics of several different forest sites in the uplands of interior Alaska. Then we used a cold, wet permafrost site to examine the ecological consequences of direct moss and tree interactions. Our analyses revealed a tightly coupled system in which forest succession was highly sensitive to the interactions among site conditions, mosses, and trees. The effect of mosses on the soil thermal regime was a particularly important feedback. Direct interactions between mosses and trees that affected the development of a thick forest floor layer were also important. In particular, shading of moss by trees, reduced tree regeneration on moss-covered soils, and reduced moss growth with open forest canopies were also important determinants of forest succession. These complex feedbacks ensure that an ecosystem approach is needed to understand the ecology of boreal forests.     

Simulating harvesting scenarios towards the sustainable use of mangrove forest plantations

Mangrove forests appear among the most productive ecosystems on earth and provide important goods and services to tropical coastal populations. Thirty-five percent of mangrove forest areas have been lost worldwide in the last two decades. Management measures could be an option to combine human use and conservation of mangroves. These measures can be improved if their impacts are assessed before they are performed. By doing so, the best management option out of a set of all potential options can be selected in advance. The mangrove model—KiWi—has been proven to be suitable for analyzing mangrove forest dynamics in the neotropics. Here, the model was applied to mangrove management scenarios. For this, the model was parameterized to Rhizophora apiculata, one of the most common mangrove species planted in Asia for timber production. It is thus the first simulation model describing Asian mangrove plantations. The recently developed Pattern Oriented Modelling approach was used to find those parameters fitting best density patterns and dbh (diameter at breast height) size classes reported in literature. The results demonstrated that the KiWi model was able to: (1) reproduce the growth patterns of a mono-specific plantation of R. apiculata in terms of forest density and size class distribution and (2) can provide criteria for the selection of a thinning strategy within a harvesting cycle.     

粤东沿海红树林物种组成与群落特征

南海地区是全球红树林分布的中心区域之一。粤东沿海位于南海地区的北界,红树林物种组成和群落结构具有边缘性。利用卫星影像解译辅助技术,对筛选的23处红树林群落进行样地调查,记录了真红树植物12种,半红树植物6种,伴生植物7种。各群落平均高度为1.50—8.60 m,林相以灌丛、小乔木林为主。红树林群落Shannon-Wiener多样性指数为0.533—1.239,均匀度指数为0.662—0.957,天然林和人工林之间数值差异不显著。等级聚类分析将粤东沿海的红树林划分为演替早期人工林、演替早期天然林、演替中期天然林和演替后期天然林4个类别,各群落立地条件差异较大,沉积物总有机碳、盐度、总氮含量与群落分布状况的相关性较高。与1985年的报道相比,尽管该地区记录的红树林植物种类从20种增加至24种,但个别伴生植物消失以及半红树植物种群萎缩说明该地区红树林面临较大的环境压力。在物种多样性和均匀度均方面,粤东沿海红树林群落低于成熟红树林。过去数十年的围垦导致天然红树植物种群萎缩、生境破碎化是主要因素。基于该地区红树林群落的现状,未来人工林和残次天然林的优化改造是红树林恢复重建的重点,红树林恢复和保育的重点区域包括深圳湾的福田、范和港的蟹洲和韩江口的六合围。     

Influence of Forest Types and Effects of Forestry Activities on Species Richness and Composition of Chrysomelidae in the Central Mountainous Region of Japan

Species richness and composition of the Chrysomelidae (Coleoptera) were studied in larch (Larix kaempheri [Lamb.] Carrière) plantations, secondary forests, and primary forests. In addition, the effects of forest management practices, such as thinning and long rotation, were examined in the larch plantation. The species richness of Chrysomelidae was higher in the larch plantation than in the secondary forest or in the primary forest. Among the larch plantations, the species richness in old-aged plantations was higher than that in middle-aged plantations. The composition of the beetle assemblages in the larch plantation differed from that in the secondary forest or in the primary forest. Exosoma akkoae (Chujo), Batophila acutangula Heikertinger, and Calomicrus nobyi Chujo were caught with a bias toward the larch plantation. Longitarsus succineus (Foudras) and Sphaeroderma tarsatum Baly were caught more in the secondary forest and the primary forest, respectively. More B. acutangula and S. tarsatum were caught in stands where their host plants occurred at higher rates. Species richness of understory plants was an important factor for chrysomlid species richness, and frequency of host occurrence affected the number of individuals of leaf beetles examined. It seems that forest types and forest management practices affect host plants as well as Chrysomelidae, and that these effects on the host plants also influence chrysomelid assemblages.     

Can we predict carbon stocks in tropical ecosystems from tree diversity? Comparing species and functional diversity in a plantation and a natural forest

? Linking tree diversity to carbon storage can provide further motivation to conserve tropical forests and to design carbon-enriched plantations. Here, we examine the role of tree diversity and functional traits in determining carbon storage in a mixed-species plantation and in a natural tropical forest in Panama. ? We used species richness, functional trait diversity, species dominance and functional trait dominance to predict tree carbon storage across these two forests. Then we compared the species ranking based on wood density, maximum diameter, maximum height, and leaf mass per area (LMA) between sites to reveal how these values changed between different forests. ? Increased species richness, a higher proportion of nitrogen fixers and species with low LMA increased carbon storage in the mixed-species plantation, while a higher proportion of large trees and species with high LMA increased tree carbon storage in the natural forest. Furthermore, we found that tree species varied greatly in their absolute and relative values between study sites. ? Different results in different forests mean that we cannot easily predict carbon storage capacity in natural forests using data from experimental plantations. Managers should be cautious when applying functional traits measured in natural populations in the design of carbon-enriched plantations.     

油樟幼苗对马尾松林窗面积的光合响应特征

为了解马尾松人工林窗对伴生树种的影响,为马尾松人工纯林的团块状混交提供科学依据,研究了10 m×10 m(T1)、15 m×15 m(T2)、20 m×20 m(T3)、25 m×25 m(T4)、30 m×30 m(T5)、35 m×35 m(T6)和40 m×40 m(T7)马尾松人工林窗中油樟(Cinnamomum longepaniculatum)幼苗叶片形态和光合生理特征的变化,探讨马尾松林窗斑块对混生树种生长的影响。结果表明:1)林窗面积低于20 m×20 m时,油樟幼苗叶片最大净光合速率显著低于旷地对照;2)叶片比叶重随着林窗面积的增大显著升高;林窗内油樟幼苗叶氮含量在小林窗中(10 m×10 m)显著低于旷地对照,但在大林窗中(如20 m×20 m)显著高于对照;林窗内幼苗叶磷含量则与旷地无显著性差异;3)叶氮在光合组分中的总分配系数随着林窗面积的增加而增大,其中叶氮在羧化组分中的分配系数升高尤为明显,而捕光组分的分配系数在林窗面积10 m×10 m—20 m×20 m范围内随林窗面积的增加而显著降低。可见,当马尾松林窗面积低于20 m×20 m时,林窗环境会显著影响油樟幼苗的光合能力,油樟幼苗可以通过调节比叶面积、叶氮含量以及叶氮在光合组分中的分配等形态、生理适应特征来适应林窗环境的变化。     

浑善达克沙地榆树疏林和小叶杨人工林碳密度特征及其与林龄的关系

榆树(Ulmus pumila)疏林是浑善达克沙地的地带性隐域植被, 小叶杨(Populus simonii)是该区域主要的防风固沙造林树种。该文通过测定两种森林生态系统乔木层(叶、枝、干、根)、草本层(地上植被和地下根系)和土壤层(0-100 cm)的碳含量, 比较了两种森林生态系统的碳密度及其分配特征, 并运用空间代替时间的方法, 阐明了乔木层、土壤层和总碳密度随林龄增加的变化特征, 估算了两种森林生态系统的固碳速率。结果表明, 榆树疏林乔木层和土壤层平均碳含量都低于小叶杨人工林, 榆树疏林生态系统总碳密度是小叶杨人工林的1/2。两种森林生态系统的总碳密度中, 乔木层碳密度和土壤层碳密度总占比98%以上; 土壤层与植被层碳密度的比值随林龄的增加而降低, 过熟林时该比值分别为1.66 (榆树疏林)和1.87 (小叶杨人工林); 榆树疏林和小叶杨人工林的乔木层、土壤层和生态系统的总碳密度随林龄的增加而增加, 其中乔木层碳密度及榆树疏林总碳密度与林龄均呈现出显著的线性正相关关系。小叶杨人工林乔木层的固碳速率约为榆树疏林的5倍, 榆树疏林生态系统和小叶杨人工林生态系统的总固碳速率分别为0.81 Mg C·hm^-2·a^-1和5.35 Mg C·hm^-2·a^-1。这一研究结果有利于估算沙地森林生态系统的碳储量, 为区域生态环境恢复和增加碳汇的政策制定提供依据。     

Recovery of species diversity and composition of braconid parasitic wasps after reforestation of degraded grasslands in lowland East Kalimantan

Human-induced disturbances and wildfires can transform areas of tropical rainforest into Imperata-dominated grassland, but it may be possible that recovery of biodiversity is facilitated by reforestation with fast-growing trees. We compared the assemblages of braconid wasps as parasitoids of taxonomically diverse groups of insects among Imperata grasslands, young and mature plantations of Acacia mangium, young secondary forests after wildfires, and old secondary forests in the lowland of East Kalimantan. The abundance and species richness of braconids, which had declined in Imperata grasslands, somewhat increased in Acacia plantations, and also the species composition of braconids in Acacia plantations was transitional between Imperata grasslands and old secondary forests. Parasitoids of detritivores and wood borers increased markedly after plantation, while those of herbivores showed a distinct turnover of species all over the range from grasslands to old secondary forests. The plantation of A. mangium had most likely facilitated the recovery of the diversity of host forest and their parasitoids, but the recovery was just at the rudimentary stage even in mature plantations. Monitoring of parasitic wasps would be useful to test the continuous recovery of forest biodiversity in plantation stands.     

Cultivation of Non‐timber Forest Products Alters Understory Light Availability in a Humid Tropical Forest in Mexico1

The planting of non‐timber forest products (NTFPs) in the understory of tropical forests is promoted in many regions as a strategy to conserve forested lands and meet the economic needs of rural communities. While the forest canopy is left intact in most understory plantations, much of the midstory and understory vegetation is removed in order to increase light availability for cultivated species. We assessed the extent to which the removal of vegetation in understory plantations of Chamaedorea hooperiana Hodel (Arecaceae) alters understory light conditions. We also examined how any changes in light availability may be reflected by changes in the composition of canopy tree seedlings regenerating in understory plantations. We employed a blocked design consisting of four C. hooperiana plantation sites; each site was paired with an adjacent, unmanaged forest site. Hemispherical canopy photographs were taken and canopy tree seedlings were identified and measured within 12 3 × 2 m randomly placed plots in each site for a total of 96 plots (4 blocks × 2 sites × 12 plots). Plantation management did not affect canopy openness or direct light availability but understory plantations had a higher frequency of plots with greater total and diffuse light availability than unmanaged forest. Comparisons of canopy tree seedling composition between understory plantations and unmanaged forest sites were less conclusive but suggest that management practices have the potential to increase the proportion of shade‐intolerant species of tree seedlings establishing in plantations. Given the importance of advanced regeneration in gap‐phase forest dynamics, these changes may have implications for future patterns of succession in the areas of forest where NTFPs are cultivated.     

马尾松人工林不同大小林窗植物多样性及其季节动态

人工林目前存在结构单一、土壤退化、生物多样性降低等人类普遍关注的生态问题。马尾松(Pinus massoniana)是长江上游低山丘陵区退耕还林的主要人工林树种。研究采伐林窗对植物物种组成和更新的影响, 对马尾松低效人工林的改造, 提升其生态服务功能具有重要的意义。该文以采伐39年生的马尾松人工林形成的7种不同大小的林窗为研究对象, 分析了不同季节林窗内的植物生活型组成及多样性变化。结果表明: 1)马尾松人工林林下植物以高位芽植物居多, 其次是地面、地下芽植物, 一年生植物较少而缺少地上芽植物。在林窗形成初期, 林窗的高位芽植物比例明显低于林下, 大林窗的高位芽植物比例稍高于小林窗, 地下芽和一年生植物的比例低于小林窗。2)林下的物种丰富度和物种多样性指数显著低于大林窗。不同林窗下植物的丰富度指数、优势度指数、多样性指数也存在显著差异。3)夏季林窗下植物多样性最高, 其次是秋季, 春季多样性最低。1225-1600 m²的大林窗能够促进马尾松人工林植物多样性恢复和植被更新。     

Plant diversity and seasonal dynamics in forest gaps of varying sizes in Pinus massoniana plantations

人工林目前存在结构单一、土壤退化、生物多样性降低等人类普遍关注的生态问题。马尾松(Pinus massoniana)是长江上游低山丘陵区退耕还林的主要人工林树种。研究采伐林窗对植物物种组成和更新的影响, 对马尾松低效人工林的改造, 提升其生态服务功能具有重要的意义。该文以采伐39年生的马尾松人工林形成的7种不同大小的林窗为研究对象, 分析了不同季节林窗内的植物生活型组成及多样性变化。结果表明: 1)马尾松人工林林下植物以高位芽植物居多, 其次是地面、地下芽植物, 一年生植物较少而缺少地上芽植物。在林窗形成初期, 林窗的高位芽植物比例明显低于林下, 大林窗的高位芽植物比例稍高于小林窗, 地下芽和一年生植物的比例低于小林窗。2)林下的物种丰富度和物种多样性指数显著低于大林窗。不同林窗下植物的丰富度指数、优势度指数、多样性指数也存在显著差异。3)夏季林窗下植物多样性最高, 其次是秋季, 春季多样性最低。1225-1600 m²的大林窗能够促进马尾松人工林植物多样性恢复和植被更新。