Semi-natural Vegetation Research Articles

Strong restrictions on the trait range of co-occurring species in the newly created riparian zone of the Three Gorges Reservoir Area, China

Abstract Aims Community assembly links plant traits to particular environmental conditions. Numerous studies have adopted a trait-based approach to understand both community assembly processes and changes in plant functional traits along environmental gradients. In most cases these are long-established, natural or semi-natural environments. However, increasingly human activity has created, and continues to create, a range of new environmental conditions, and understanding community assembly in these ‘novel environments’ will be increasingly important. Methods Built in 2006, the Three Gorges Dam, largest hydraulic project in China, created a new riparian area of 384 km2, with massively altered hydrology. This large, newly created ecosystem is an ideal platform for understanding community assembly in a novel environment. We sampled environment variables and plant communities within 103 plots located in both the reservoir riparian zone (RRZ) and adjacent non-flooded and semi-natural upland (Upland) at the Three Gorges Reservoir Area. We measured six traits from 168 plant species in order to calculate community-level distribution of trait values. We expected that the altered hydrology in RRZ would have a profound effect on the community assembly process for the local plants. Important Findings Consistent with previous work on community assembly, the distribution of trait values (range, variance, kurtosis and the standard deviation of the distribution neighbor distances) within all plots was significantly lower than those from random distributions, indicating that both habitat filtering and limiting similarity simultaneously shaped the distributions of traits and the assembly of plant communities. Considering the newly created RRZ relative to nearby sites, community assembly was different in two main ways. First, there was a large shift in the mean trait values. Compared to Upland communities, plant communities in the RRZ had higher mean specific leaf area (SLA), higher nitrogen per unit leaf mass (Nmass), and lower maximum height (MH). Second, in the RRZ compared to the Upland, for the percentage of individual plots whose characteristic of trait values was lower than null distributions, the reductions in the community-level range for SLA, Nmass, nitrogen per unit leaf area (Narea) and phosphorus per unit leaf area (Parea) were much larger, suggesting that the habitat filter in this newly created riparian zone was much stronger compared to longer established semi-natural upland vegetation. This stronger filter, and the restriction to a subset of plants with very similar trait values, has implications for predicting riparian ecosystems’ responses to the hydrological alterations and further understanding for human’s effect on plant diversity and plant floras.

Invasion impact is conditioned by initial vegetation states

Biological invasion is a crucial problem in the world because of its negative consequences for protected areas. The degradation stage of vegetation might affect the success of invasion. One of the most abundant and threatening invasive species is the common milkweed (Asclepias syriaca L.) which has invaded already 23 countries of Europe and in several habitat types its further spreading is promoted by climate change. Pannonian sand grassland is one of the most threatened habitat by common milkweed invasion. Therefore, invasion in sand grassland vegetation is an important issue. However, the effects of the invasive plant in the open sand grassland are rather controversial. In order to clarify the existing contradictory results, the study was carried out in a strictly protected area, near Fülöpháza (Hungary) in a reserve core area in a UNESCO biosphere reserve. Microcoenological study was applied to determinate the fine-scale community characteristics of non-invaded and invaded stands in natural and seminatural vegetation and data were processed by Juhász-Nagy’s information theory models. Shannon diversity of species combinations (compositional diversity) which describes the ways of the coexistence of species, and the number of realized species combinations were used for measuring beta diversity. Differences between stands were analyzed by two-way ANOVA. The maximum compositional diversity of species and main life-forms (annuals, perennials and cryptogams) did not differ significantly between the non-invaded and invaded stands. In contrast, significantly larger characteristic areas of compositional diversity were detected in the invaded stands. Based on these results, it could be concluded that diversity of species combinations did not change but those values have shifted to coarser scales in case of invaded stands. The direction of this change suggests a kind of impoverishment in the presence of Asclepias. Thus, it is worth mentioning from the invasion management point of view that protection of the habitats against disturbance is a more cost-effective and successful way than protection against the establishment or extirpation of invasive species, since disturbance facilitates the invasions throughout the impoverishment of the community.

Non-crop habitats promote the abundance of predatory ladybeetles in maize fields in the agricultural landscape of northern China

Ladybeetles are promising contributors of biological control services in agricultural landscapes, potentially providing significant economic gains in agricultural production. In northern China, ladybeetles are the most common predators in the annual double-crop rotation system, where the dominant crops are wheat in the spring and maize and cotton in the summer. Land-use features at the landscape level affect ladybeetle populations in a number of ways, and our previous studies have estimated the effects of landscape composition on ladybeetles abundance in wheat and cotton fields in northern China. However, these landscape effects on ladybeetle abundance in maize remain insufficiently documented in this specific agro-ecosystem. We assessed the relationships between ladybeetle abundance and landscape composition at four spatial scales (0.5, 1.0, 1.5, and 2.0 km) in a summer maize system at the whorl stage (the main period for ladybeetle colonization). We found that both semi-natural habitats (woodlots and grasslands) and vegetation around water bodies increased the abundance of ladybeetles in maize fields, and maize area played a dilution effect on ladybeetle abundance in this crop. These non-crop habitats might serve as source of emigrants that disperse to maize fields. The smallest scale (0.5 km) studied was the most predictive spatial scale in this colonization period for ladybeetles. Propylaea japonica, the dominant ladybeetle, showed response to landscape variables in a similar way as the whole ladybeetle population did. These findings suggest that leaving some non-crop habitats and reducing human disturbance to this vegetation within a landscape will enhance ladybeetle abundance in maize fields. Consistent with our previous studies in wheat and cotton fields in the same system, maintaining the continuity in time and space of functional habitats was essential for the persistence of ladybeetle populations within the landscape. In the future, habitat management and landscape design to ensure resource continuity should be encouraged to maximize the conservation of ladybeetles in agricultural ecosystems in northern China.

Landscape restoration in a mixed agricultural-forest catchment: Planning a buffer strip and hedgerow network in a Chilean biodiversity hotspot.

Guidance for large-scale restoration of natural or semi-natural linear vegetation elements that takes into account the need to maintain human livelihoods such as farming is often lacking. Focusing on a Chilean biodiversity hotspot, we assessed the landscape in terms of existing woody vegetation elements and proposed a buffer strip and hedgerow network. We used spatial analysis based on Google Earth imagery and QGIS, field surveys, seven guidelines linked to prioritization criteria and seedling availability in the region's nurseries, and estimated the budget for implementing the proposed network. The target landscapes require restoring 0.89hakm-2 of woody buffer strips to meet Chilean law; 1.4hakm-2 of new hedgerows is also proposed. The cost of restoration in this landscape is estimated in ca. USD 6900 per planted ha of buffer strips and hedgerows. Financial incentives, education, and professional training of farmers are identified as key issues to implement the suggested restoration actions.

Agricultural Expansion-Induced Infiltration Rate Change in a West African Tropical Catchment

Land use and land cover in the Dano catchment is characterized by a rapid conversion from seminatural vegetation (fallow) to agriculture (cropland). The study compares both the saturated (Ks) and the unsaturated (Kh) hydraulic conductivities under cropland and fallow in the catchment to gain insights into the effect of the current land use on soil water dynamics. Hydraulic conductivity was measured under forty-two (42) pairs of adjacent cropland-fallow plots using a Hood infiltrometer. Ks, Kh, bulk density, and soil texture were further compared using a paired two-tailed Student’s t-test (p=0.05). The results showed that both Ks and Kh are highly variable irrespective of the land use type (coefficient of variation > 100%). The results also showed that Ks was significantly higher (1.16-fold on average) under fallow compared to cropland. As for Kh, the results showed that, from −2 cm to zero tension heads (h), Kh under cropland and fallow is not significantly different; however, as the supplied tension decreases up to the saturation state, Kh under fallow becomes statistically higher compared to cropland. No significant difference was found between soil textures and bulk density under cropland and fallow meaning that the observed differences of Ks and Kh under cropland and fallow were caused by land use and not preexisting difference in texture. These results suggest an increasing risk of erosion, soil fertility reduction, and flood in the catchment because of agricultural land expansion.

Environmental Sensitivity Index Mapping: A Case Study of PPMC Pipeline along Ugbomro Community and Environ, Delta State, Nigeria

Environmental Sensitivity Index (ESI) mapping provide a concise summary of coastal/inland resources that are at risk if an oil spill occurs nearby. Environmental sensitivity index (ESI) maps can be used for oil spill contingency planning, environment management planning and emergency response. To this end, the study attempts to establish the inland habitats and their sensitivity to oil spill along the 4.95km of the pipeline passing through Ugbomro community and as it relates to its environs. Ikonos image of the area obtained from Google Earth, were digitized manually and the land use/land cover map of the areas were derived using ArcGIS 10.1. The ESI classification and ranking was done for the inland habitat by considering the importance of indigenous flora/fauna species to rural livelihood, oil ecosystem interaction, and ease of clean up. The result suggests that built up area, water body and wetland having ESI ranking to be Very High and ESI classification of 5A, 5B and 5C respectively. Farmland ESI ranks High with ESI classification of 4, Semi natural vegetation has ESI ranking of Medium with ESI classification of 2 and bare surfaces had ESI ranking to be Low and ESI classified as 1. An emergency response zone and priority booming were proposed along the pipeline route as a means of curtailing the spread of oils to sensitive resources.

Exploring relationships between land use intensity, habitat heterogeneity and biodiversity to identify and monitor areas of High Nature Value farming

Understanding how species richness is distributed across landscapes and which variables may be used as predictors is important for spatially targeting management interventions. This study uses finely resolved data over a large geographical area to explore relationships between land-use intensity, habitat heterogeneity and species richness of multiple taxa. It aims to identify surrogate landscape metrics, valid for a range of taxa, which can be used to map and monitor High Nature Value farmland (HNV).Results show that variation in species richness is distributed along two axes: land-use intensity and habitat heterogeneity. At low intensity land-use, species rich groups include wetland plants, plant habitat indicators, upland birds and rare invertebrates, whilst richness of other species groups (farmland birds, butterflies, bees) was associated with higher land-use intensity. Habitat heterogeneity (broadleaved woodland connectivity, hedgerows, habitat diversity) was positively related to species richness of many taxa, both generalists (plants, butterflies, bees) and specialists (rare birds, woodland birds, plants, butterflies).The results were used to create maps of HNV farmland. The proportion of semi-natural vegetation is a useful metric for identifying HNV type 1. HNV type 2 (defined as a mosaic of low-intensity habitats and structural elements) is more difficult to predict from surrogate variables, due to complex relationships between biodiversity and habitat heterogeneity and inadequacies of current remotely sensed data.This approach, using fine-scaled field survey data collected at regular intervals, in conjunction with remotely sensed data offers potential for extrapolating modelled results nationally, and importantly, can be used to assess change over time.

Different agricultural practices affect soil carbon, nitrogen and phosphorous in Kilombero -Tanzania

Converting natural and semi-natural vegetation to agriculture is currently the most significant land use change at global scale. This conversion leads to changes in soil nutrients and increased CO2 emissions. However, knowledge of how soil organic carbon and nutrients change under various farming management is still limited, especially for small scale farming systems. This study evaluated the effects of different farming systems on soil organic carbon (SOC), total nitrogen (TN) and total phosphorous (TP) in subsistence farming at Kilombero, Tanzania. We applied an in-situ experimental setup, comparing maize and rice farming with and without irrigation and difference in fertilizers, with replicated soil sampling at five soil depths to a depth of 60 cm. The results show that irrigation had a positive effect on profile-averaged concentrations of SOC and TN, while fertilization had a positive effect on TN. Higher concentrations and stocks of TN were found in maize field soils compered to rice fields. In the vertical profile, irrigation and fertilization had positive effects on concentrations of SOC and TN of top soil layers, and the interaction between irrigation and fertilization extended the effect to deeper soil layers. Our results indicate that moderate irrigation and fertilization can help to improve carbon storage and nutrient availability (TN) in small-scale farming soils in Africa.

Increasing local biodiversity in urban environments: Community development in semi-natural species-rich forb vegetation

There is much interest in supporting biodiversity through eye-catching low maintenance requiring herbaceous vegetation types in urban environments. Community development of forb vegetation is not well understood, and experimental studies investigating the potentials and limitations of establishing such vegetation are needed. We performed a field experiment including three mixtures of 19 forb species (three annuals, three biennials, 13 perennials) and analysed the development of the community over 3 years. In spring 2010 a total of 3630 seedling plug plants were transplanted in a randomized block experiment with 30 plots; non-planted control plots were monitored as reference. Management was limited to removal of dead plant material in February. We documented transplant survivorship, gap colonisation and soil seed bank composition. Standing biomass was harvested in a subset of plots in August 2012, and in all plots in July 2013. After four growing seasons, 1592 transplants were still alive. Fifteen experimental species had spread to gaps, but grasses, Achillea millefolium and Trifolium pratense var. sativum were the most frequent gap-colonizers. On average, biomass of non-experimental species contributed only 11% to the total aboveground biomass in treatment mixtures after four growing seasons. The initial proportions of species (annuals vs perennials) had no significant effect on the community's resistance to colonisation by non-experimental species. Biomass of non-experimental species was negatively correlated to transplant survival. Thus, high plant density increases resistance to invasion, but long-term persistence of forb vegetation is species-specific. In practice some disturbance is necessary to facilitate regeneration of desirable forbs.

Anthropisation Et Dynamique Des Paysages En Pays Agonlin Au Bénin

The temporal dynamics of landscapes in pays Agonlin zone of south Benin (West Africa) were studied through a diachronic analysis of three Landsat images (TM 1986, ETM 2000 et OLI TIR, 2015), supported by field visits. The results indicate that the forest cover was reduced from 35.46 % in 1986 to 9.97 % in 2016. This decrease of forest area went together with a loss of savannah area. On the other hand, agricultural areas increased up to 23.21% over the same period. Landscape pattern analysis by means of configuration metrics revealed a fragmentation of natural and seminatural vegetation by agricultural activities, leading to an aggregation of agricultural patches. As general trend, human activities and demographic growth have caused significant changes to the landscapes of the study region.

Invasive plants of the Kampinos National Park outskirts – the current state and threats to the protected area

Studies aimed at the identification of the range and the ways of spread of invasive alien plants in the Kampinos National Park (KNP) outskirts were carried out between 2012 and mid 2018. Special emphasis was placed on surveying the sites of the invasive species and diagnosing potential threats posed to the natural and semi-natural vegetation of the national park by them in rural areas. A floristic survey was carried out on the majority (93 localities) of settlement areas in the vicinity of KNP, in its buffer zone, frequently near the border of the park. Thirty-nine invasive taxa were found which may potentially pose a threat to the ecosystems of KNP. The most frequently identified species included trees and shrubs: Acer negundo, Rhus typhina, Robinia pseudoacacia, Partenocissuss inserta, and herbaceous plants: Conyza canadensis, Erigeron annuus, Solidago serotinoides, S. canadensis. Species encroaching from the settlement areas to semi-natural and natural communities include Bidens frondosa, Echinocystis lobata, Impatiens glandulifera, I. parviflora, Juncus tenuis, Lupinus polyphyllus, Reynoutria japonica, R. xbohemica and Solidago serotinoides. Most of them are species from the highest (III and IV) classes of invasiveness in Poland. The close distance to the Warsaw conurbation, and the road network developed around KNP has certainly affected the number of alien species recorded in the analysed area. Urbanized lands neighbouring the Park are still probably a source from where alien plants disperse to the protected area.

Semi-natural grassland vegetation in landslides after the 4 and 26 years in Aso, Kumamoto Prefecture

Semi-natural grassland vegetation in landslides after the 4 and 26 years in Aso, Kumamoto Prefecture

Coincidence of High Nature Value farmlands with bird and butterfly diversity

The amount of High Nature Value farmland (HNVf) is a commonly used environmental indicator for assessing the performance of the Common Agricultural Policy, to support sustainable agriculture and monitor changes in agricultural land use in Europe. HNVf comprises agricultural areas of semi-natural state, low-intensity farming and fine-scale landscape mosaics of different habitat types. For a successful implementation, the identification of HNVf should correctly reflect the variation in biodiversity values between different agricultural landscapes. We examined how well the Finnish HNVf indicator and the sub-indicators constituting it – recalculated for the purposes of this study for five study regions – reflect the variation in bird and butterfly species richness and diversity patterns at different spatial scales. We found that butterfly diversity index was positively associated with the HNVf indicator at the finest scale of 0.5 km × 0.5 km squares. Among the HNVf sub-indicators, extensive cultivation of grasslands was most strongly related to the farmland bird diversity and the density of edge to the butterfly diversity. Thus, the HNVf concept reflects well the distribution of butterflies in the Finnish agricultural landscapes but insufficiently the diversity patterns of farmland birds. Importantly, semi-natural vegetation and long-term pastures – the backbone of the concept – presently occur in small and highly fragmented patches in agricultural landscapes in Finland. The Pan-European concept of HNVf has restricted application to farmland birds of this boreal country and the national HNVf concept may need to be revised.

The enhancing effect of afforestation over secondary succession on soil quality under semiarid climate conditions

Semiarid climate conditions hamper natural re-vegetation, leaving the soil vulnerable to erosion after the cessation of agriculture. Therefore, soil and landscape protective measures, especially afforestations, have been implemented in the Mediterranean region since the early 20th century. This study aims to determine the long term impact of afforestation on soil functioning, in comparison with natural re-vegetation (secondary succession) on abandoned fields and semi-natural vegetation.A comparison of secondary succession and afforestation with the present traditional rain fed cereal fields and semi-natural (open) forest, including natural resource islands, was made as well. Composite soil samples were taken to study the physical (i.e. texture, aggregate stability) and chemical (i.e. carbon content, nutrient availability) soil characteristics after 20 and 40 years of afforestation and secondary natural succession. To take into account the resource island effect, the spatial heterogeneity induced by differences in plant cover, samples were taken both below and in between the tree canopy of the semi-natural and afforested Pinus halepensis trees.Our results indicate that under secondary succession on abandoned fields, soil quality improves non-linearly and only marginally over a time of 40 years. The afforestation showed a much more pronounced linear increase for most soil quality indicators, resulting in soil conditions comparable to what can be found under the semi-natural forest vegetation. Site preparation might have been a crucial factor for the success of ecosystem restoration in the studied dry land area as it improved water availability for the afforestation.

Effect of landscape diversity and crop management on the control of the millet head miner, Heliocheilus albipunctella (Lepidoptera: Noctuidae) by natural enemies

The pearl millet head miner, Heliocheilus albipunctella, is a major constraint to increasing crop productivity in sub-Saharan Africa. In the absence of any insecticide application by farmers, its control mostly relies on the action of natural enemies.The objective of the present study is to identify crop management and landscape features affecting biocontrol services by natural enemies. A set of 45 millet fields were selected in a 20 ∗ 20 km area in Senegal, from the analysis of high resolution satellite images (Pleiades), and hypotheses on relative abundance of millet fields and semi-natural habitats (mainly trees) in the agricultural landscape. A biocontrol service index (BSI) was computed for each field over two cropping seasons by experimentally excluding natural enemies from naturally egg-infested millet panicles. Information on crop management was collected through farmer’s interviews. An information theoretical approach and model averaging were performed to rank the effect of landscape metrics on BSI at eight spatial scales (from 250 to 2000 m).The BSI was generally high (77%) but highly variable among fields (0–100%), and was greater in compound fields compared to bush fields. The BSI also increased with the abundance of tree patches and the diversity of vegetation in a 1750 m-buffer around millet fields.Results support previous studies stressing the importance of semi-natural areas and vegetation diversity to support pest regulation by natural enemies. Further research is needed to better understand relationships between agroforestry systems and biological control, to promote ecologically-intensive solutions for reducing crop losses.

Land surface greening suggests vigorous woody regrowth throughout European semi-natural vegetation.

The satellite record has revealed substantial land surface "greening" in the northern hemisphere over recent decades. Process-based Earth system models (ESMs) attribute enhanced vegetation productivity (greening) to CO2 fertilisation. However, the models poorly reproduce observed spatial patterns of greening, suggesting that they ignore crucial processes. Here, we explore whether fine-scale land cover dynamics, as modified by ecological and land-use processes, can explain the discrepancy between models and satellite-based estimates of greening. We used 500m satellite-derived Leaf Area Index (LAI) to quantify greening. We focus on semi-natural vegetation in Europe, and distinguish between conservation areas and unprotected land. Within these ecological and land-use categories, we then explored the relationships between vegetation change and major climatic gradients. Despite the relatively short time-series (15years), we found a strong overall increase in LAI (i.e., greening) across all European semi-natural vegetation types. The spatial pattern of vegetation change identifies land-use change, particularly land abandonment, as a major initiator of vegetation change both in- and outside of protected areas. The strongest LAI increases were observed in mild climates, consistent with more vigorous woody regrowth after cessation of intensive management in these environments. Surprisingly, rates of vegetation change within protected areas did not differ significantly from unprotected semi-natural vegetation. Overall, the detected LAI increases are consistent with previous, coarser-scale, studies. The evidence indicates that woody regrowth following land abandonment is an important driver of land surface greening throughout Europe. The results offer an explanation for the large discrepancies between ESM-derived and satellite-derived greening estimates and thus generate new avenues for improving the ESMs on which we rely for crucial climate forecasts.

Effects of land use on infestation and parasitism rates of cabbage seed weevil in oilseed rape.

This study investigated how infestation rates of an important oilseed rape pest, the cabbage seed weevil (Ceutorhynchus obstrictus) and rates of parasitization by its parasitoids are affected by land use, up to 1000 m from 18 focal fields. The mean proportion of C. obstrictus-infested pods per plant was 8% (2-19.5%). Infestation rates were higher if the adjacent habitat was a herbaceous semi-natural habitat than if it was either another crop or a woody habitat. Infestation rates were positively related to the area of herbaceous semi-natural vegetation, permanent grassland and wheat (which followed oilseed rape in the crop rotation) at a spatial scale of at least 1 km. The mean parasitism rate of C. obstrictus larvae was 55% (8.3-87%), sufficient to provide efficient biocontrol. Parasitism rates were unrelated to adjacent habitats, however, they were positively related to the presence of herbaceous linear elements in the landscape and negatively related to permanent grasslands at a spatial scale of 200 m. Proximity of herbaceous elements increased both infestation rates and parasitism, while infestation was also related to landscape factors at larger distances. The findings provide an empirical basis for designing landscapes that suppress C. obstrictus, at both field and landscape scales. © 2018 Society of Chemical Industry.

Natural vegetation and bug abundance promote insectivorous bat activity in macadamia orchards, South Africa

Accelerating land use change is associated with the loss of species and their ecosystem services. South Africa is the world's largest producer of macadamias and the industry continues to grow. Insectivorous bat species are important for pest control, but bat populations are declining. Therefore, proactive management of bat communities in agricultural landscapes is essential. We acoustically monitored bats and used light traps to catch arthropods during one annual cycle, sampling five macadamia orchards monthly in Limpopo, South Africa. We used GIS and R to analyse both the general bat and foraging bat activity of the two main foraging guilds (open-air/clutter edge guild) in different land use types and total activity with respect to arthropod abundances. Overall clutter edge guild activity (number of passes) decreased with macadamia and orchard (all other fruit) cover in the high season and increased with bush cover and distance to settlements (potential roosts) in the low season. Open-air guild activity increased with fallow cover in the high season. Foraging activity (feeding buzzes) of the clutter edge guild increased with bush cover over the whole year. Total activity (both guilds) increased with abundance of true bugs, including the main macadamia pests, and bush cover.In conclusion, natural and semi-natural vegetation promote bat activity in macadamia orchards, and potentially bats' provision of the ecosystem service of pest control. In times of accelerating land use change, remnants of natural vegetation are important refuges and need to be maintained or restored. The installation of bathouses might further improve bat activity.

Climate change could threaten cocoa production: Effects of 2015-16 El Niño-related drought on cocoa agroforests in Bahia, Brazil

Climate models predict a possible increase in the frequency of strong climate events such as El Niño-Southern Oscillation (ENSO), which in parts of the tropics are the cause of exceptional droughts, these threaten global food production. Agroforestry systems are often suggested as promising diversification options to increase farmers' resilience to extreme climatic events. In the Northeastern state of Bahia, where most Brazilian cocoa is grown in wildlife-friendly agroforests, ENSOs cause severe droughts which negatively affect forest and agriculture. Cocoa (Theobroma cacao) is described as being sensitive to drought but there are no field-studies of the effect of ENSO-related drought on adult cocoa trees in the America's; there is one study of an experimentally-imposed drought in Indonesia which resulted in 10 to 46% yield loss. In our study, in randomly chosen farms in Bahia, Brazil, we measured the effect of the 2015–16 severe ENSO, which caused an unprecedented drought in cocoa agroforests. We show that drought caused high cocoa tree mortality (15%) and severely decreased cocoa yield (89%); the drought also increased infection rate of the chronic fungal disease witches' broom (Moniliophthora perniciosa). Ours findings showed that Brazilian cocoa agroforests are at risk and that increasing frequency of strong droughts are likely to cause decreased cocoa yields in the coming decades. Furthermore, because cocoa, like many crops, is grown somewhat beyond its climatic limits, it and other crops could be the 'canaries in the coalmine' warning of forthcoming major drought effects on semi-natural and natural vegetation.

Species composition and distribution of Coleosporium species on the needles of Pinus densiflora at a semi-natural vegetation succession site in central Japan

Coleosporium species cause pine needle rust. Most species have heteromacrocyclic life cycles, and 12 species use Pinus densiflora as aecial hosts. To understand the biology of rust fungi and develop better methods for controlling rust diseases, it is necessary to clarify that which Coleosporium species affect pine trees. However, Coleosporium on pine trees have rarely been identified at the species level because of their morphological similarities. We used polymerase chain reaction - restriction fragment length polymorphism (PCR-RFLP) to clarify the species composition, abundance, and distribution of Coleosporium in a P. densiflora forest. We surveyed a site where several Coleosporium species might complete their life cycles. PCR-RFLP revealed four species on the pines: C. asterum, C. clematidis-apiifoliae, C. lycopodis, and C. phellodendri. Coleosporium phellodendri was distributed throughout the forest and was the most abundant. Aecia of C. phellodendri formed mainly on 2-y-old needles. The abundance and distribution of C. phellodendri appeared to be affected by the longer effective dispersal range of basidiospores and the existence of abundant inoculum sources. The age of leaves where C. phellodendri form aecia mainly was thought to be influenced by the characteristic life cycle, with aecial formation requiring 2 y after basidiospore infection.