Reconstruction of June–September precipitation based on tree-ring data of teak (Tectona grandis L.) from Hoshangabad, Madhya Pradesh, India

An attempt has been made to explore dendroclimatological potentiality of teak (Tectona grandis L.) towards the reconstruction of climate from a new geographical region. Growth of this tree has been found to be limited by the low monsoon precipitation. Based on ring-width data of teak, mean monsoon precipitation of June–September has been reconstructed back to AD 1835. The reconstructed climate records show several alternating periods of high and low monsoon episodes. Many of these low monsoon years have been recorded to coincide with most of the known principal drought years of India.     

The diet and feeding behavior of the silver leaf monkey (Trachypithecus auratus sondaicus) in Indonesia

I describe the diet and feeding behavior of silver leaf monkeys (Trachypithecus auratus sondaicus) in the Pangandaran Nature Reserve, West Java, Indonesia, and compare a group living in old secondary rain forest with a group living in mixed plantation/secondary forest to determine intraspecific variation in feeding behavior and the importance of the plantation species in the diet of the monkeys. Young leaves and leaf buds made up slightly less than half of their diets, with both groups showing a preference for a few species when seasonally available. Fruits and flowers of a few species were also preferentially selected when available. These included sweet, fleshy fruits, which most other colobines tend to avoid. Young leaf intake was greatest in months when fruit intake was low. Mature leaves were rarely eaten. Both groups spent approximately 20% of feeding time foraging on Moraceae species. Differences in the diet of the two groups were related largely to differences in vegetational composition and the availability and abundance of food items for the species common to both sites. Teak (Tectona grandis) was the top food species of the group living in mixed plantation/secondary forest, with the midribs of young leaves preferentially selected. Young leaves ofT. grandis, available throughout the study, provided a staple food and were eaten when preferred foods were scarce. More favored food items were available to the group living in old secondary forest, though none was a staple food.     

Development and characterization of microsatellite markers in Tectona grandis (Linn. f)

Teak (Tectona grandis Linn. f) is a hardwood species of worldwide reputation. It occurs naturally in India, Thailand, Myanmar and Laos. Fifteen highly polymorphic microsatellite loci were developed from a genomic library enriched for AG/TC repeats. Primers to amplify these loci were tested on 265 individual trees from different teak populations. An average of 14.7 alleles per locus were detected and expected heterozygosity ranged from 0.223 to 0.879. These loci constitute a powerful tool in investigating the mating system, gene flow, parentage analysis and population dynamics for use in sustainable management of teak forests and for in situ conservation purposes.     

羊草与大针茅根系构型对水分梯度响应的比较研究

羊草(Leymus chinensis)与大针茅(Stipa grandis)是内蒙古锡林郭勒典型草原的两大建群种,也是内蒙古草原的重要优良牧草。选取锡林郭勒草原以大针茅和羊草为优势种的围封草场为研究样地,通过原状土柱移栽,进行了两年的水分梯度控制实验(150、300、450、600 mm),分别模拟当地年降雨量由干旱年到是湿润年的变化情况,分析比较羊草种群和大针茅种群地上高度和根系构型对水分梯度的响应情况。结果表明:相比大针茅种群,羊草种群对水分梯度的响应更敏感,随着水分梯度的增加,羊草地上高度和根系直径显著增加,根系长度和根系深度显著减少;而大针茅的地上高度和根系特征各项指标均没有显出与水分梯度的相关性,显然大针茅比羊草更能适应干旱生境。在干旱条件(模拟年降雨量150 mm处理)下,大针茅种群地上高度达到峰值,生长状况良好;羊草种群则采用地上个体小型化,地下主根变细,分叉,向土壤深层扩展的生长策略。因此,在气候变化背景下,干旱化的气候将导致大针茅种群在群落中的优势地位逐渐增加,反之羊草种群则会随着气候湿润化而占据更大的优势。     

Quantifying tree carbon stock in historically conserved Seminary Hills urban forest of Nagpur,India

Urban forests help regulating flow of ecosystem services and are efficient to sequester atmospheric carbon. Tree carbon stock in urban forests and green spaces can help improving human well-being. Nagpur being one of the fastest growing urban agglomerate in India that has faced rapid loss of green spaces in last three decades. Present study assessed tree biomass carbon storage potential of a historically conserved large (67.41 ha) Seminary Hills Reserve forest of Nagpur. A total of 150 quadrats of 100 m² were laid to understand the vegetation structure and tree biomass storage. Overall structure and composition of the forest was assessed while, non-destructive biomass estimation was carried out using tree volume eqs. A total of 27 tree species belonging to 12 plant families were observed from the forest with only 6 tree species being dominant and remaining 21 being rare in occurrence. The maximum tree carbon storage was observed in dominant tree species of Hardwickia binata (76.30 t C ha^?1) followed by 17.04 t C ha^?1 in Tectona grandis and 1.19 t C ha^?1 in Boswellia serrata. Carbon stock in other co-dominant species was reported in Terminalia bellirica (76.57 kg C ha^?1), Gardenia resinifera (1118.6 g C ha^?1) and Terminalia arjuna (84.8 g C ha^?1). Total carbon stock of dominant tree species present in Seminary Hills urban forest was 94.53 ± 39.6 t C ha^?1. The study intends to bring focus ecosystem benefits from Urban Forests in growing urban sprawls of India and the need to include their vital role in urban planning.     

Changes in structure of over‐ and midstory tree species in a Mediterranean‐type forest after an extreme drought‐associated heatwave

Worldwide, extreme climatic events such as drought and heatwaves are associated with forest mortality. However, the precise drivers of tree mortality at individual and stand levels vary considerably, with substantial gaps in knowledge across studies in biomes and continents. In 2010–2011, a drought‐associated heatwave occurred in south‐western Australia and drove sudden and rapid forest canopy collapse. Working in the Northern Jarrah (Eucalyptus marginata) Forest, we quantified the response of key overstory (E. marginata, Corymbia calophylla) and midstory (Banksia grandis, Allocasuarina fraseriana) tree species to the extreme climate event. Using transects spanning a gradient of drought impacts (minimal (50–100 m), transitional (100–150 m) and severe (30–60 m)), tree species mortality in relation to stand characteristics (stand basal area and stem density) and edaphic factors (soil depth) was determined. We show differential mortality between the two overstory species and the two midstory species corresponding to the drought‐associated heatwave. The dominant overstory species, E. marginata, had significantly higher mortality (~19%) than C. calophylla (~7%) in the severe zone. The midstory species, B. grandis, demonstrated substantially higher mortality (~59%) than A. fraseriana (~4%) in the transitional zone. Banksia grandis exhibited a substantial shift in structure in response to the drought‐associated heatwave in relation to tree size, basal area and soil depth. This study illustrates the role of climate extremes in driving ecosystem change and highlights the critical need to identify and quantify the resulting impact to help predict future forest die‐off events and to underpin forest management and conservation.     

Diversity and conservation of forest-floor arthropods on a small Seychelles island

Cousine Island, Seychelles, is of major conservation significance as it is in a biodiversity hotspot. Furthermore, it is relatively pristine, and is apparently the only tropical island over 20 ha with no alien invasive mammals. This study focuses on the island's log and litter arthropods, which were sampled by extraction methods from the dominant species, Pisonia grandis, Ficus spp. and Cocos nucifera. Stage of decomposition, and forest type in which the logs occurred, both significantly influenced the composition and structure of the arthropod assemblages. Young logs were significantly richer in species than older logs, possibly because they had the most resources and microhabitats. There were some significant changes in arthropod species richness, composition and abundance between species of young logs, but not old ones, because as logs decomposed, arthropod assemblages converged. Nevertheless, each old log species had some arthropod species not present in other log species, which has important implications for conservation. Arthropod assemblages in woody litter varied according to the forest type in which they occurred, and were different from those in logs in the same forest type. Cousine Island arthropod species richness, both in logs and litter, was comparable to figures from other tropical areas. As the logs, especially P. grandis, are home to many Seychelles endemic species, their conservation is essential. Furthermore, as the arthropods are also the main food of certain threatened Seychelles vertebrates, their conservation also underpins a food chain on this unique tropical island.     

不同干扰下阿拉善荒漠啮齿动物优势种对气候变化的响应

气候变化已对物种分布范围和丰富度产生了极大的影响。荒漠生态系统对气候变化的反应可能更加敏感。作为荒漠生态系统的重要组成者,了解荒漠啮齿动物特别是优势鼠种将对气候变化如何响应,对于荒漠地区生物多样性的维持将具有重要意义。2002—2010年,采用标志重捕法对阿拉善荒漠4种不同生境下啮齿动物优势种群进行了研究,分别利用Spearman相关分析以及典范对应分析(Canonical Correspondence analysis,CCA)对啮齿动物优势种群动态与年平均温度和年降水量的相关性进行了分析。结果表明,不同啮齿动物优势种对温度和降雨的响应不同,尤其以子午沙鼠表现最为显著。跳鼠对温度的适宜性要高于仓鼠科的子午沙鼠和黑线仓鼠,而仓鼠科啮齿动物对降雨的适宜性高于跳鼠。较小尺度上的人为干扰更可能从改变食性和生境的途径上加剧或缓冲降雨对荒漠啮齿动物优势种的影响,而不是改变温度对啮齿动物的作用。     

Effects of grazing on photosynthetic characteristics of major steppe species in the Xilin River Basin,Inner Mongolia,China

Species composition and photosynthetic characteristics of dominant species of ungrazed plot (UG), overgrazed plot (OG), and restored grazed plot (RG) were determined in the Xilin River Basin, Inner Mongolia, China. Both heavily grazing and restoration significantly affected the composition of different species and life forms. Leymus chinensis, Stipa grandis, and Cleistogenes polyphylla, three dominant perennial grasses in UG plot, contributed 58.9 % aboveground biomass to that of whole community, and showed higher net photosynthetic rate (P _N), transpiration rate (E), and intrinsic water-use efficiency (WUE). In OG plot, relative biomass of L. chinensis and S. grandis significantly decreased, while relative biomass of three shrubs/sub-shrubs, Caragana microphylla, Artemisia frigida, and Kochia prostrata, obviously increased. Heavy grazing significantly decreased P _N, E, and WUE of L. chinensis and S. grandis, while shrubs/sub-shrubs showed significantly higher photosynthetic activity and WUE than the grasses. After 18-year restoration, photosynthetic activities of L. chinensis and S. grandis were significantly higher than those in the OG plot. The proportion of L. chinensis, S. grandis, and C. microphylla significantly increased, and relative biomass of C. polyphylla, A. frigida, and K. prostrata markedly declined in RG plot. We found close relationships between physiological properties of species and their competitive advantage in different land use types. Higher photosynthetic capability means more contribution to total biomass. The variations in physiological characteristics of plants could partly explain the changes in species composition during degrading and restoring processes of Inner Mongolia typical steppes.     

Density‐dependence in common tree species in a tropical dry forest in Mudumalai,southern India

Abstract. Density‐dependence in tree population dynamics has seldom been examined in dry tropical forests. Using long‐term data from a large permanent plot, this study examined 16 common species in a dry tropical forest in southern India for density‐dependence. Employing quadrat‐based analyses, correlations of mortality, recruitment and population change with tree densities were examined. Mortality in 1–10 cm diameter trees was largely negatively correlated with conspecific density, whereas mortality in > 10 cm diameter trees was positively correlated. Mortality was, however, largely unaffected by the basal area and abundance of heterospecific trees. Recruitment was poor in most species, but in Lagerstroemia microcarpa (Lythraceae), Tectona grandis (Verbenaceae) and Cassia fistula (Fabaceae), species that recruited well, strong negative correlations of recruitment with conspecific basal area and abundance were found. In a few other species that could be tested, recruitment was again negatively correlated with conspecific density. In Lagerstroemia, recruitment was positively correlated with the basal area and abundance of heterospecific trees, but these correlations were non‐significant in other species. Similarly, although the rates of population change were negatively correlated with conspecific density they were positive when dry‐season ground fires occurred in the plot. Thus, the observed positive density‐dependence in large‐tree mortality and the negative density‐dependence in recruitment in many species were such that could potentially regulate tree populations. However, repeated fires influenced density‐dependence in the rates of population change in a way that could promote a few common species in the tree community.     

Chloroplast DNA variation and population structure in the widespread forest tree, Eucalyptus grandis

Recognition of genetic structure of populations and the ability to identify vulnerable populations is useful for the formation of conservation management strategies for plants. Eucalyptus grandis is a tall forest tree that has a major area of occurrence in subtropical eastern Australia, with smaller populations located in the east coast tropics. Many widespread forest species exhibit population differentiation that corresponds to geographic regions. However, Eucalyptus grandis appears to be an exception based on isozyme and morphological data. This is intriguing given a large discontinuity between northern populations and those in the southern part of the species range. In this study, the distribution of a maternally inherited chloroplast locus was examined because it was more likely to reveal genetic structure due to the slower evolution of the chloroplast genome and limited dispersal of seed in eucalypts. As expected, the G _ST for chloroplast DNA was higher than that for nuclear DNA but indicated low population differentiation for a forest tree species. Phylogeographic analysis indicated that the 15 populations grouped into three broad geographical regions; however, overall population structure was weak suggesting that the large geographical disjunction in the distribution of E. grandis may be relatively recent. A paradigm for conservation management of E. grandis based on chloroplast DNA haplotype distribution would take into account the low differentiation among populations.     

Incidence and management of white grub, Schizonycha ruficollis on seedlings of teak （Tectona grandis Linn, f,）

In investigation was conducted annually from 2002 to 2005 between the second week of May and the end of September on the incidence of scarab beetle, Schizonycha ruficollis （Fabricius） in a teak （Tectona grandis L.f.） nursery at Ramdongari, Nagpur, India. The immature stages, that is white grubs of the scarab beetle damaged 14%-52% of teak seedlings in the nursery beds, whereas the adult of the species, that is scarab beetles, were recorded on three new host trees （ Ziziphus xylopyra, Acacia catechu and A. leucophloea） in addition to the reported hosts such as ziziphus （Z. jujuba and Z. mauritiana）. Beetles of the S. ruficollis started emerging from the nursery beds just after the pre-monsoon showers and continued for 10-18 days. While beetle of S. ruficollis defoliated tree hosts available in the surroundings, the immature stages of the beetle caused major damage by feeding on root systerfls of teak seedlings with symptoms of wilting and mortality in forest nursery beds. The result of chemical and biological treatments for the management of grubs of S. ruficollis in nursery beds indicated phorate 10% granular at the rate of 20 g/m^2 and chlorpyriphos 20% emulsifiable concentrate at the rate of 5.0 mL/m^2 to be effective. Grubs of S. ruficollis have not been recorded previously as a major pest of teak （T. grandis）. This is also the first report on occurrence of S. ruficollis adults on tree hosts such as Z. xylopyra, A. catechu and A. leucophloea. White grubs being pests of economic importance and the toughest insects to manage, information given in this paper on incidence, pest status and management of Schizonycha ruficollis is of importance to researchers and forest nursery managers.     

Arthropod Diversity in Lama Forest Reserve (South Benin), a Mosaic of Natural, Degraded and Plantation Forests

Arthropod assemblages were examined in Lama forest reserve, a protected area situated in the Dahomey gap, southern Benin, composed of plantations, degraded forest and remnants of natural forest. The objectives were to compare assemblages in relation to forest type and use, to elucidate the value of forest plantations for biodiversity conservation and to identify indicator species for specific forest habitats. Arthropods were collected over an 11-month period, using standardized sets of traps (pitfall, emergence, Malaise and flight intercept traps). Nine different habitats were studied, including natural and degraded forest, forest plantations (Tectona grandis and Senna siamea) of different age, and isolated forest fragments. Our analysis focused on detritivorous and xylophagous arthropods but also included ground beetles and heteropterans, totalling 393 species. We found no differences in species richness among natural and degraded forest habitats in the centre of the reserve (Noyau central). Outside of the Noyau central, species richness was highest in old teak plantations and isolated forest fragments and lowest in young teak and fuelwood plantations. Detrended correspondence analysis (DCA) separated three main groups: (1) natural forest, (2) degraded forest and young plantations, and (3) old plantations and isolated forest fragments. Multiple regression of DCA scores of the first two axes on environmental variables identified one natural and three disturbance-related predictors of arthropod assemblages in Lama forest: soil type (texture), canopy height, naturalness (proportion of Guineo-Congolian plant species) and understorey vegetation cover. We identified 15 indicator species for six different forest habitats. The highest numbers were found in abandoned settlements and old teak plantations. β-diversity was similar among the three DCA ordination groups (degraded forest excluded). Values for β-diversity were relatively high, suggesting that all major forest habitats contribute significantly to regional species pools and should therefore be protected. To enhance arthropod diversity, we propose that management practices in Lama forest should aim to encourage the development of species-rich understorey vegetation of the Guineo-Congolian phytogeographical region.     

A 7000‐year history of changing plant trait composition in an Amazonian landscape; the role of humans and climate

Tropical forests are shifting in species and trait composition, but the main underlying causes remain unclear because of the short temporal scales of most studies. Here, we develop a novel approach by linking functional trait data with 7000 years of forest dynamics from a fossil pollen record of Lake Sauce in the Peruvian Amazon. We evaluate how climate and human disturbances affect community trait composition. We found weak relationships between environmental conditions and traits at the taxon level, but strong effects for community‐mean traits. Overall, community‐mean traits were more responsive to human disturbances than to climate change; human‐induced erosion increased the dominance of dense‐wooded, non‐zoochorous species with compound leaves, and human‐induced fire increased the dominance of tall, zoochorous taxa with large seeds and simple leaves. This information can help to enhance our understanding of forest responses to past environmental changes, and improve predictions of future changes in tropical forest composition.     

What is the role of disturbance in catalyzing spatial shifts in forest composition and tree species biomass under climate change?

Mounting evidence suggests that climate change will cause shifts of tree species range and abundance (biomass). Abundance changes under climate change are likely to occur prior to a detectable range shift. Disturbances are expected to directly affect tree species abundance and composition, and could profoundly influence tree species spatial distribution within a geographical region. However, how multiple disturbance regimes will interact with changing climate to alter the spatial distribution of species abundance remains unclear. We simulated such forest demographic processes using a forest landscape succession and disturbance model (LANDIS-II) parameterized with forest inventory data in the northeastern United States. Our study incorporated climate change under a high-emission future and disturbance regimes varying with gradients of intensities and spatial extents. The results suggest that disturbances catalyze changes in tree species abundance and composition under a changing climate, but the effects of disturbances differ by intensity and extent. Moderate disturbances and large extent disturbances have limited effects, while high-intensity disturbances accelerate changes by removing cohorts of mid- and late-successional species, creating opportunities for early-successional species. High-intensity disturbances result in the northern movement of early-successional species and the southern movement of late-successional species abundances. Our study is among the first to systematically investigate how disturbance extent and intensity interact to determine the spatial distribution of changes in species abundance and forest composition.     

Survival, growth and gall formation by Phytolyma lata on Milicia excelsa established in mixed-species tropical plantations in Ghana

1 Milicia excelsa (Moraceae) is an important timber tree in much of Africa and when grown in monocultural plantations has been subject to nearly complete destruction by gall-forming psyllids in the genus Phytolyma. 2 We tested the impact on susceptibility to Phytolyma spp. of planting Milicia excelsa in various densities and species mixtures. Replicated plantings consisting of 11, 25, 50 and 100% Milicia in mixtures with Terminalia superba (Combretaceae) were established at a site surrounded by natural forest and in an agricultural area. 3 In addition at the agricultural site, 50–50 mixtures of Milicia excelsa with Albizia adianthifolia (Mimosaceae), Tectona grandis (Verbenaceae), Khaya ivorensis. (Meliaceae), Ceiba pentandra (Bombacaceae) and a mixture combining all species were planted. 4 Two months after planting, gall numbers were significantly lower in the 11% Milicia mixtures at the forest site. Gall numbers were also significantly lower at the forest site than at the agricultural site, for all densities of Milicia. At 6 months, dieback of Milicia resulting from gall formation had taken place equally on all seedlings, but survival of seedlings at the forest site was 40% higher than at the agricultural site.     

El Niño and related monsoon drought signals in 523-year-long ring width records of teak (Tectona grandis L.F.) trees from south India

We present a 523-year (A.D. 1481–2003) tree-ring width index chronology of Teak (Tectona grandis L.F.) from Kerala, Southern India, prepared from three forest sites. Dendroclimatological investigations indicate a significant positive relationship between the tree-ring index series and Indian summer monsoon rainfall (ISMR) and related global parameters like the Southern Oscillation Index (SOI). A higher frequency of occurrence of low tree growth is observed in years of deficient Indian monsoon rainfall (droughts) associated with El Niño since the late 18th century. Prior to that time, many low tree growth years are detected during known El Niño events, probably related to deficient Indian monsoon rainfall. The general relationship between ISMR and El Niño is known to be negative and the spatial correlations between our Kerala tree-ring chronology and sea surface temperatures (SSTs) over the Niño regions follow similar patterns as those for ISMR. This relationship indicates strong ENSO-related monsoon signals in the tree-ring records. These tree-ring chronologies with a high degree of sensitivity to monsoon climate are useful tools to understand the vagaries of monsoon rainfall prior to the period of recorded data.     

阿尔泰山萨彦岭4种优势树种径向生长对气候因子的响应

气候变化深刻地影响森林树木的生长,而树种对气候变化敏感度的差异可能影响了气候变化下的森林生态系统响应。因此,研究优势树种间生长对气候变化的敏感度差异,对正确认识气候变化下林分生长动态及分布格局十分重要。基于树木年代学的方法,研究了阿尔泰山萨彦岭西伯利亚落叶松（Larix sibirica）、西伯利亚红松（Pinus sibirica）、西伯利亚冷杉（Abies sibirica）以及西伯利亚云杉（Picea obovata）4种优势树种的径向生长-气候关系。结果显示：（1）西伯利亚冷杉径向生长与上一年10-11月、当年1-9月的干旱指数、2-4月的降水显著正相关,与1月的平均温和最高温呈显著负相关关系,与当年4、6月份的水汽压正相关;（2）西伯利亚落叶松径向生长与上一年8月和当年8月的平均温、最高温以及当年8月的最低温显著负相关,而与当年6月的最低温则正相关,与8月份的水汽压显著负相关;（3）西伯利亚红松径向生长与3月降水、7月最低温、上一年10月的水汽压显著正相关;（4）西伯利亚云杉径向生长与6月平均温、最高温、水汽压正相关,与上一年10-11月、当年2-4月和9月的干旱指数正相关,同时与3、4月的降水量显著正相关。西伯利亚冷杉和西伯利亚云杉、西伯利亚云杉和西伯利亚落叶松、西伯利亚云杉和西伯利亚红松对于特定气候因子表现出相似的响应结果,与年表间相关性的结果一致。但差异也是明显的,西伯利亚冷杉和西伯利亚云杉对区域水分变化敏感,而西伯利亚落叶松和西伯利亚红松主要对区域温度变化敏感。综上所述,气候变化下,该区域优势树种对气候变化响应的差异可能导致区域林分动态和格局的改变,因此,多树种径向生长-气候关系研究有助于正确反映森林动态。研究结果可以为区域森林管理与生态保护工作提供理论依据。