Quaternary plant fossils from the Jebel Marra volcanic complex and their palaeoclimatic interpretation

The fossil plants from the Malha Crater, previously referred to as Cyperus papyrus L. have been re-identified as Phragmites sp.; since determination to species is not possible, this record can have no phytogeographical or palaeoclimatic significance.Olea sp., probably O. laperrinei Batt. et Trab. from Jebel Marra, dated 3 500 B.P. raises interesting but so far speculative considerations regarding the inter-relationship of Mediterranean and tropical African species in the southern Sahara during the last pluvial period.Leaf impressions of the oil palm, Elaeis guineensis Jacq. from Jebel Marra, where it is no longer to be found, plus considerations regarding other surviving forest species in the gallery forests, suggest a minimum northwards climatic shift during the last pluvial in the order of 400 km.This fossil record is regarded as suggesting that the source of the oil palm kernel discovered at the Neolithic site of Esh Shaheinab, near Khartoum, is probably Jebel Marra.     

Cladocera from the Sudan: Red Sea Hills,Jebel Marra and valley of the main Nile

Twenty species of Cladocera are reported from the Nile, where lacustrine species dominate, and from Jebel Marra and the Red Sea Hills, where chydorids dominate. The community found in the Red Sea Hills is more typically desertic than that of Jebel Marra, which appears closely related to the fauna of the West and Central African Sahel.     

The mammals of Jebel Marra, Sudan

A small collection of mammals was made on Jebel Marra, Darfur Province, Sudan, in November 1964. Fifteen species were collected and information is given on their habitat, reproductive condition, and moulting. A general account of Jebel Marra and a list of the 36 recorded mammals from the mountain are included.     

Woody vegetation composition and diversity in woodlands inside and outside a Forest Reserve in Jos,Nigeria

Protected areas such as forest reserves are often assumed to be best ways to conserve biodiversity and maintain intact ecosystems. We examined woody plant composition and diversity in the gallery forest and savannah woodland habitats of Amurum Forest Reserve and areas immediately surrounding it in Jos, Nigeria. A total of 100 10 × 10 m sample plots were established inside and outside the reserve. All woody plants ≥1 cm diameter at breast height (dbh) were identified and measured. A total of 7,564 individual plants categorized as 134 species from 44 families were recorded. Overall species diversity was significantly higher in the Forest Reserve than outside the reserve, although more species were encountered outside the reserve. Our findings suggest that, protected areas and the areas surrounding them are important for the conservation of biodiversity as the areas outside protected areas also contain species of conservation value. The continuous degrading areas outside protected areas isolates them and poses a serious threat to the long‐term viability of wildlife populations, so it is important that biodiversity in protected areas and their surrounding areas be conserved.     

Studies on the freshwater algae of the Sudan II. The distribution of the bacillariophyceae of Wadi Galol,Jebel Marra

The diatom flora of a district in Jebel Marra, Sudan, has been qualitatively analysed. The periphyton is related to the type of substratum with which the various diatoms associated. Certain diatoms were found to be restricted to one habitat, while others were common to more than one. All species recorded belong to the Pennales. Comparison with regions in the Southern and Northern hemisphere is made.     

Restoration of Araucaria Forest: The Role of Perches, Pioneer Vegetation, and Soil Fertility

The Araucaria forest is Brazil's highly threatened subtropical forest ecosystem that has been disappearing in recent decades. Restoration programs involving this forest type are scarce, and there is a lack of scientific information on how ecological processes such as competition, facilitation, and seed dispersal influence natural forest restoration. This work aims to investigate how use of perches to attract seed dispersers and the influence of pioneer vegetation and soil fertilization could affect the colonization of woody species in a degraded area. An experiment was conducted in an abandoned field where the natural establishment of seeds and seedlings of woody species was monitored under factorial combinations of the following treatments: (1) pioneer vegetation (presence and absence); (2) soil fertility (addition of NPK and control); and (3) perches (presence and absence). Seed and seedling abundance, seed and seedling species richness, and seedling mortality were recorded monthly during 12 months. Seed abundance and species richness were significantly greater in places with perches than in control plots. These results were consistent over the year and more pronounced when the surrounding forest produced a higher amount of fruit. Species richness and abundance of seedlings were significantly greater in places with perches than in control plots, and in places with vegetation than without. Soil fertility did not influence seedling establishment. Facilitation and seed dispersal are important factors affecting the colonization of woody species in this subtropical area. Nutrient availability neither regulates the facilitation process nor influences species replacement during the early stages of Araucaria forest succession.     

Woody Species Diversity in Forest Plantations in a Mountainous Region of Beijing,China: Effects of Sampling Scale and Species Selection

The role of forest plantations in biodiversity conservation has gained more attention in recent years. However, most work on evaluating the diversity of forest plantations focuses only on one spatial scale; thus, we examined the effects of sampling scale on diversity in forest plantations. We designed a hierarchical sampling strategy to collect data on woody species diversity in planted pine (Pinus tabuliformis Carr.), planted larch (Larix principis-rupprechtii Mayr.), and natural secondary deciduous broadleaf forests in a mountainous region of Beijing, China. Additive diversity partition analysis showed that, compared to natural forests, the planted pine forests had a different woody species diversity partitioning pattern at multi-scales (except the Simpson diversity in the regeneration layer), while the larch plantations did not show multi-scale diversity partitioning patterns that were obviously different from those in the natural secondary broadleaf forest. Compare to the natural secondary broadleaf forests, the effects of planted pine forests on woody species diversity are dependent on the sampling scale and layers selected for analysis. Diversity in the planted larch forest, however, was not significantly different from that in the natural forest for all diversity components at all sampling levels. Our work demonstrated that the species selected for afforestation and the sampling scales selected for data analysis alter the conclusions on the levels of diversity supported by plantations. We suggest that a wide range of scales should be considered in the evaluation of the role of forest plantations on biodiversity conservation.     

The distribution and status of the montane juniper woodlands of Oman

Abstract. The distribution, condition and reproductive status of Juniperus excelsa M. -Bieb. subsp. polycarpos (K.Koch) Takhtajan were determined and assessed in the Hajar mountains of northern Oman, Arabia. Juniper is restricted to the highest areas, viz the central massif of Jebel Akhdar and the outlying mountains of Jebel Qubal and Jebel Kawr, where it generally forms open woodlands.
On exposed slopes juniper is distributed from an altitude of 2100 m to the highest summit at 3009 m, with no upper tree line, while on well-shaded north-facing slopes juniper trees grow as low as 1375 m. Above 2300 m, juniper is the dominant woody species, while below this altitude it is often co-dominant with Olea europea L. The woodlands are generally in poor condition on exposed slopes below 2400 m, with high proportions of dead or dying trees and low proportions of reproductively active trees. Above 2400 m and in shaded sites, woodland condition is better, with markedly higher proportions of reproductively active trees on exposed slopes at these altitudes. A predictive model of woodland condition based on topographic variables is presented. Altitude, shade and habitat account for 30.8% of the variation in a tree condition index, with slope being unimportant.
The absence of juniper from lower and more outlying mountains is likely to have resulted from the alternation of pluvial and arid periods over the last 40,000 years. We speculate that the current dieback of juniper at lower altitudes is due to continuing climatic change. Anthropogenic factors do not appear to be seriously affecting the juniper woodlands at present.     

Effects of large herbivores on wood pasture dynamics in a European wetland system

Whether self-regulating large herbivores play a key role in the development of wood-pasture landscapes remains a crucial unanswered question for both ecological theory and nature conservation. We describe and analyse how a ‘partly self-regulating’ population of cattle, horses and red deer affected the development of the woody vegetation in the Oostvaardersplassen nature reserve (Netherlands). Using aerial photographs from 1980 to 2011, we analysed the development of shrubs and trees. Before the large herbivores were introduced in the Oostvaardersplassen in 1983, the woody vegetation increased and vegetation type significantly affected the number of establishments. Cover of woody species increased further from 1983 to 1996, not only by canopy expansion but also by new establishments. After 1996, cover of the woody vegetation decreased from 30% to <1% in 2011 and no new establishments were seen on the photographs. Survival of Sambucus nigra and Salix spp. increased with increasing distance to grassland, which is the preferred foraging habitat of the herbivores. These results support the hypothesis of Associational Palatability. In addition, our results show that the relative decline in cover of S. nigra and Salix spp. over a certain period was negatively correlated with the cover of S. nigra in the beginning of this period, presenting some evidence for the Associational Resistance and Aggregational Resistance hypothesis. Our research shows aspects necessary for the woodland–grassland cycle, such as a strong decline of woody vegetation at high numbers of large herbivores and regeneration of shrubs and trees at low densities. Thorny shrubs, which are important for the cycle, have not yet established in the grasslands. It seems that a temporary decline in herbivore numbers is necessary to create a window of opportunity for the establishment of these woody species.     

A review of the rotifer fauna of the Sudan

A collection of rotifers contained in samples from the Blue, White and joint Niles in the Sudan, the Red Sea Hills, and Jebel Marra mountains is studied, and the previous literature on the rotifera of Sudan is reviewed. A total of 145 rotifer taxa are now known from this country. Ecological and distributional notes on selected species are added. Besides cosmopolitan, pantropical, and tropical species, a small but significant fraction of the fauna is of northern origin, possibly reflecting climatic conditions of the late-Pleistocene.     

Role of nurse plants in Araucaria Forest expansion over grassland in south Brazil

Abstract Araucaria Forest expansion over grassland takes place under wet climate conditions and low disturbance and it is hypothesized that isolated trees established on grassland facilitate the establishment of forest woody species beneath their canopies. Forest with Araucaria angustifolia is a particular type of Brazilian Atlantic Forest and the main forest type on the highland plateau in south Brazil, often forming mosaics with natural Campos grassland. The objectives of this paper were to evaluate the role of isolated shrubs and trees as colonization sites for seedlings of Araucaria Forest woody species on grassland, to determine which species function as preferential nurse plants in the process and the importance of vertebrate diaspore dispersal on the structure of seedling communities beneath nurse plants. The study was conducted in São Francisco de Paula, Rio Grande do Sul State, where we sampled isolated shrubs and trees in natural grassland near Araucaria Forest edges. Seedlings were counted and identified, and seedling diaspore dispersal syndromes, size and colour were registered. We detected 11 woody species with a potential role in nucleating grassland colonization by forest species. Beneath the canopies of nurse plants more forest species seedlings were found compared with open field grassland and the seedlings had diaspores mostly dispersed by vertebrates. Also, more seedlings were found under the canopy of A. angustifolia than beneath other nurse plant species. We conclude that A. angustifolia trees established on grassland act as nurse plants, by attracting disperser birds that promote colonization of the site by other forest species seedlings, and that under low level of grassland disturbance, conservation of frugivorous vertebrate assemblages may increase forest expansion over natural grassland and also facilitate the regeneration of degraded forest areas.     

Are protected areas maintaining bird diversity?

Evaluating the effectiveness of protected areas for sustaining biodiversity is crucial to achieving conservation outcomes. While studies of effectiveness have improved our understanding of protected‐area design and management, few investigations (< 5%) have quantified the ecological performance of reserves for conserving species. Here, we present an empirical evaluation of protected‐area effectiveness using long‐term measures of a vulnerable assemblage of species. We compare forest and woodland bird diversity in the Australian Capital Territory over 11 yr on protected and unprotected areas located in temperate eucalypt woodland and matched by key habitat attributes. We examine separately the response of birds to protected areas established prior to 1995 and after 1995 when fundamental changes were made to regional conservation policy. Bird diversity was measured in richness, occurrence of vulnerable species, individual species trajectories and functional trait groups. We found that protected areas were effective in maintaining woody vegetation cover in the study region, but were less effective in the protection of the target bird species assemblage. Protected areas were less species rich than unprotected areas, with significant declines in richness across sites protected prior to 1995. Small, specialised and vulnerable species showed stronger associations with unprotected areas than protected areas. Our findings indicate that recently established reserves (post‐1995) are performing similarly to unprotected woodland areas in terms of maintaining woodland bird diversity, and that both of these areas are more effective in the conservation of woodland bird populations than reserves established prior to 1995. We demonstrate that the conservation value of protected areas is strongly influenced by the physical characteristics, as well as the landscape context, of a given reserve and can diminish with changes in surrounding land use over time. Both protected areas and off‐reserve conservation schemes have important roles to play in securing species populations.     

Convergence Between Dung Beetle Assemblages of a Post-Mining Vegetational Chronosequence and Unmined Dune Forest

Abstract In Maputaland, South Africa vegetative and microclimatic changes on mined dunes drive the composition of the dung beetle fauna toward convergence with that in natural dune forest on unmined dunes. We assessed the pattern of these changes using a 23‐year vegetational chronosequence on mined dunes, which passes from grassland (approximately 1 year) to open Acacia shrubland thicket to Acacia karroo‐dominated woodland (approximately 9 years). Across this sequence, which represents successional stages in the restoration of dune forest, there was a sequential trend toward convergence in dung beetle species composition in both the entire species complement and, particularly, in shade specialist species. However, species abundance patterns showed a trend toward convergence only in early chronosequence Acacia woodland, followed by a decline in similarity between dung beetle assemblages of older Acacia woodland and unmined natural forest. This trend toward divergence was common both to the entire species complement, which includes widespread taxa, and to species endemic to Maputaland or the east coast. These trends in similarity and dissimilarity between dung beetle assemblages closely parallel the greater physiognomic and microclimatic similarity between early Acacia woodland and natural forest and the relative dissimilarity of older Acacia woodland. In conclusion, although percentage similarities between dung beetle assemblages of approximately 12‐year woodland and natural forests were comparable with those between each natural forest stand, decline in similarity in older woodland stands suggests that lasting convergence in dung beetle species abundance will only be attained once the Acacia woodland is replaced by secondary natural forest.     

Variation in woody plant mortality and dieback from severe drought among soils, plant groups, and species within a northern Arizona ecotone

Vegetation change from drought-induced mortality can alter ecosystem community structure, biodiversity, and services. Although drought-induced mortality of woody plants has increased globally with recent warming, influences of soil type, tree and shrub groups, and species are poorly understood. Following the severe 2002 drought in northern Arizona, we surveyed woody plant mortality and canopy dieback of live trees and shrubs at the forest–woodland ecotone on soils derived from three soil parent materials (cinder, flow basalt, sedimentary) that differed in texture and rockiness. Our first of three major findings was that soil parent material had little effect on mortality of both trees and shrubs, yet canopy dieback of trees was influenced by parent material; dieback was highest on the cinder for pinyon pine (Pinus edulis) and one-seed juniper (Juniperus monosperma). Ponderosa pine (Pinus ponderosa) dieback was not sensitive to parent material. Second, shrubs had similar mortality, but greater canopy dieback, than trees. Third, pinyon and ponderosa pines had greater mortality than juniper, yet juniper had greater dieback, reflecting different hydraulic characteristics among these tree species. Our results show that impacts of severe drought on woody plants differed among tree species and tree and shrub groups, and such impacts were widespread over different soils in the southwestern U.S. Increasing frequency of severe drought with climate warming will likely cause similar mortality to trees and shrubs over major soil types at the forest–woodland ecotone in this region, but due to greater mortality of other tree species, tree cover will shift from a mixture of species to dominance by junipers and shrubs. Surviving junipers and shrubs will also likely have diminished leaf area due to canopy dieback.     

基于森林碳库动态评估神农架国家级自然保护区的保护成效

保护区是维持生物多样性和生态系统功能的最有效方式, 但其保护成效有待提升, 土地利用变化是重要影响因素之一。本研究以神农架国家级自然保护区为对象, 基于神农架地区近20年的调查研究和数据积累, 通过异速生长模型、生物量方程、抽样加权等方法, 对比分析了土地利用方式转变格局下神农架国家级自然保护区森林生态系统地上、地下、凋落物、粗木质残体、土壤有机碳5个碳库动态, 分析论证了20年间(1990-2010)神农架保护区对森林生态系统碳库的保护成效。研究发现, 林地占神农架保护区总面积的92.76%, 其中针叶林(51.85%)、落叶阔叶林(35.11%)及常绿阔叶林(4.47%)3种森林类型合计占林地面积的98.56%。20年间神农架保护区林地面积增加了0.11%, 灌木林地和耕地面积分别减少了8.85%和6.06%。神农架保护区2010年碳储量为24.24 Tg C (22.57-26.62 Tg C), 土壤有机碳和地上碳合计占全部碳储量的90.68%。常绿阔叶林、落叶阔叶林和针叶林3种森林类型碳储量占神农架保护区碳储量的95%。20年间神农架保护区5个碳库碳储量均有所增加, 共固碳25.04 kt C (21.83-29.57 kt C), 固碳率为1.21 kt C/年(1.09-1.48 kt C/年), 其中地上生物量碳库和土壤有机碳库分别增加14.50 kt C (11.81-18.31 kt C)和6.84 kt C。保护区内总碳库碳密度高于保护区外22.37 t C/ha。研究结果表明, 神农架国家级自然保护区在保护森林固碳能力方面取得了一定的成效。     

Ecology of Lantana camara: An invasive plant species in Amurum Forest Reserve,Jos Plateau,Central Nigeria

Lantana camara (Lantana) is an invasive species of South American origin, and it is visibly widespread in Amurum Forest Reserve (AFR) Jos-Plateau, central Nigeria. Presently, there is no baseline study on Lantana and its spread despite its conspicuous presence within AFR. This is the first study to investigate its abundance and interactions with native fauna and flora in AFR. Established study plots were used to estimate its relative abundance in three habitat types (gallery forest, savannah woodland and rocky outcrops) and to investigate its effect on plants. An experiment using cowpea-tested allelopathic effects of Lantana and focal observation/beating tray method was used to collect data on vertebrate and invertebrate species utilising/interacting with Lantana. Lantana is widespread within AFR occupying 77% of plots with the gallery forest habitat having the highest abundance compared with the savannah woodland and rocky outcrop. Plots with Lantana had fewer woody plant species than plots without Lantana. Tests on soil samples from the reserve for basic properties revealed that Lantana-infested sites had relatively poor soils compared with non-Lantana-infested sites. Birds and insects in AFR utilise Lantana and are probably responsible for its spread. Control measures are necessary to limit its spread and mitigate its likely negative effect on plant species.     

Spatial variation and biogeography of sand forest avian assemblages in South Africa

Aim To examine biogeographical affiliations, habitat‐associated heterogeneity and endemism of avian assemblages in sand forest patches and the savanna‐like mixed woodland matrix. Location Two reserves in the Maputaland Centre of Endemism (MC) on the southern Mozambique Coastal Plain of northern KwaZulu‐Natal, South Africa. Methods Replicated surveys were undertaken in each of the two habitat types in each reserve, providing species abundance data over a full year. Vegetation structure at each of the survey sites was also quantified. Differences between the bird assemblages and the extent to which vegetation structure explained these differences were assessed using multi‐variate techniques. Biogeographical comparisons were based on species presence/absence data and clustering techniques. Results Bird assemblages differed significantly between habitats both within a given reserve and between reserves, and also between reserves for a given habitat. Differences in vegetation structure contributed substantially to differences between the avian assemblages. Of the four species endemic to the MC, three (Neergaard’s sunbird, Rudd’s apalis, and Woodward’s batis) were consistently present in sand forest. The fourth (pink‐throated twinspot) preferred mixed woodland. None of these endemic species was classed as rare. In the biogeographical analysis, both the sand forest and the mixed woodland bird assemblages were most similar to bird assemblages found in the forest biome or the Afromontane forest biome, depending on the biome classification used. Main conclusions The close affinities of sand forest and mixed woodland assemblages to those of the forest biome are most likely due to similarities in vegetation structure of these forests. Bird assemblages differ between the sand forest and mixed woodland habitats both within a given reserve and between reserves, and also between reserves for a given habitat. These differences extend to species endemic to the MC. Thus, conservation of sand forest habitat in a variety of areas is necessary to ensure the long‐term persistence of the biota.     

Bamboo dominance reduces tree regeneration in a disturbed tropical forest

Human disturbance may change dominance hierarchies of plant communities, and may cause substantial changes in biotic environmental conditions if the new dominant species have properties that differ from the previous dominant species. We examined the effects of bamboos (Bambusa tulda and Cephalostachyum pergracile) and their litter on the overall woody seedling abundance, species richness and diversity in a mixed deciduous forest in northeastern Thailand. These bamboo species are gaining dominance after human disturbance. Our results show that seedling abundance and species richness were reduced by bamboo canopies. Seedling abundance and species diversity under bamboo canopies were affected by bamboo litter, whereas seedling abundance and species diversity outside bamboo canopies did not respond to the mixed-tree litter manipulation. Removal of bamboo litter increased seedling abundance and species diversity. However, bamboo litter addition did not affect seedling abundance or species diversity compared to either control or litter removal. This may indicate that the effect of natural amount of bamboo litter is as high as for litter addition in preventing seedling establishment by woody species and hence in minimizing resource competition. We conclude that undergrowth bamboos and their litter affect tree seedling regeneration differently from mixed-tree litter, causing changes in plant community composition and species diversity. Increased human disturbance, causing a shift in dominance structure of these forests, may result in a concomitant reduction in their overall woody species abundance, richness and diversity. Thus, management of bamboos by controlling their distribution in areas of high bamboo density can be an important forest restoration method.     

Patterns of vegetation along the Omo River in southwest Ethiopia

This study investigates the riverine vegetation along the perennial Omo River, which flows from the Ethiopian highlands to its terminus, in the southwestern lowlands, at Lake Turkana (formerly Lake Rudolf). Broadly defined to include the levee backslopes and adjacent mudflats (or ancient floodplains), the riverine zone in the lower Omo basin supports a relatively luxuriant vegetation compared with the dry grasslands in the surrounding plains environments. Habitat conditions along the lower Omo have changed significantly during the past century, primarily due to a period of reduced rainfall and river flow, a drop in lake level (L. Turkana) at the river's terminus and increased exposure of natural levees near the Omo's terminus. The floristic and physiognomic character of riverine vegetation were studied at selected sites, ranging from the relatively straight channel section in the modern delta to a strongly meandering (upstream) section of the river. A combination of open canopy woodland, shrub thicket and grassland (with scattered tree emergents) prevailed on the more recently exposed levees, in and near the modern delta; closed canopy woodland and forest predominated on fore levees in the meandering segment. Floristic diversity was relatively low at all study sites. Ficus sycomorus, Tapura fischeri, Melanodiscus oblongus, Celtis integrifolia and Trichilia roka were most significant in upstream forest sites, whereas Cordia sinensis, Acacia mellifera, Ziziphus mauritiana and Ficus sycomorus were more common in communities nearer the lake. Older forests generally contained greater diversity of more woody species, greater tree height and truck diameter than downstream levee vegetation, but they did not exhibit clear stratification. Species patchiness was broadly characteristic of the riverine zone, particularly the mudflats (ancient floodplains) extending away from the fore levees. Fires are frequently set by local inhabitants throughout the grasslands of the lower Omo Basin; within the riverine zone, they are particularly common in the mudflats but have only limited impact on woodland and forest vegetation. It is suggested that fire is a highly significant factor in the establishment of sharp boundaries between the closed canopy woodland/forest along the river and the more xerophytic vegetation of the mudflats.