Open Plant Research Articles

Limited Differences in Insect Herbivory on Young White Spruce Growing in Small Open Plantations and under Natural Canopies in Boreal Mixed Forests.

In managed boreal forests, both plantations and natural regeneration are used to re-establish a cohort of conifer trees following harvest or disturbance. Young trees in open plantations generally grow more rapidly than under forest canopies, but more rapid growth could be compromised by greater insect damage. We compared insect damage on white spruce (Picea glauca (Moench) Voss, Pinaceae) growing in plantations with naturally regenerated trees under mature forest canopies in boreal forests (Québec, Canada). We selected ten sites in the naturally regenerated forest and in small, multispecies plantations and sampled ten young trees of 2.5-3 m (per site) in late summer 2020 and again in early and late summer 2021. We compared overall rates of herbivory, galls (adelgids), damage by the spruce budworm (Choristoneura fumiferana, Clemens), and defoliation from sawflies. Overall, insect herbivory damage remained at similarly low levels in both habitats; an average of 9.3% of expanding shoots were damaged on forest trees and 7.7% in plantation trees. Spruce budworm damage increased from 2020 to 2021 and remained higher in under-canopy trees, but damage rates were negligible at this early stage of the outbreak (1.5% in forest vs. 0.78% of buds damaged on plantation trees). While damage due to galls was higher in plantations, the overall low level of damage likely does not pose a significant impact on the growth or mortality of young trees.

Comparison of Physical and Thermal Properties of Mulching Films Made of Different Polymeric Materials

The development of polymer materials causes their huge expansion into various areas of everyday life, as well as plant and animal production. Their chemical resistance, good physical properties, and ease of processing result in an increasing use of this group of materials. Outdoor plant production both in open plantations and greenhouses requires various types of materials supporting the vegetation process as well as protecting against pests and weeds. A large group here are various types of materials used for covers of field crops, the main role of which is to prevent uncontrolled and excessive growth of weeds and thus reduce the use of herbicides as plant protection products. Cover films also have other important functions, such as reducing direct water evaporation, better moisture retention around the root system, increasing soil temperature (faster vegetation), etc. However, as always, the problem of introducing new material into agriculture production and the difficulty of its disposal arises. In recent times, farmers' interest in various forms of mulch to protect crops and increase yields has grown significantly. In the publication, the authors attempted to analyze selected commercial properties, but also mulch produced on a laboratory scale, based on biodegradable and petroleum-derived materials.

THE RELATIONSHIP BETWEEN KNOWLEDGE AND ATTITUDE WITH EFFORT OF SCHISTOSOMIASIS PREVENTION BY COMMUNITY IN THE WORK AREA PUBLIC HEALTH CARE CENTER OF WUASA

Abstract: Schistosomiasis is a disease caused by worm Schistosoma japonicum which requires an intermediate animal, namely a snail called Oncomelania Hupensis Lindoensis. In the work area Health Care Canter of Wuasa, the disease is still many cases, because most of the population are immigrants, they are open rice fields and plantations in the focus area of snail. The purpose was to determine the relationship between knowledge and attitudes with the effort of Schistosomiasis prevention by Community in the Public Health Care Center of Wuasa, North Lore District, Poso Regency. This type of research is analytic with cross sectional approach. The variables in this study are the knowledge and attitudes of the community with efforts to prevent Schistosomiasis. The types of data are primary and secondary. data collection using a questionnaire. Data analysis used univariate and bivariate analysis with Chi-square test. The population in this study were all people of North Lore District. Sampling using proportional random sampling technique with total 99 respondents. The results of the univariate analysis showed that 77.8% of respondents had good knowledge of schistosomiasis prevention efforts, 52.5% of respondents had good attitudes and 83.8% of respondents had quite good schistosomiasis prevention efforts. Bivariate analysis with Chi-square statistical test with 95% confidence level with a significance value of 0.05. The results showed that there was a relationship between knowledge and efforts to prevent Schistosomiasis with p-value = 0.000 (where p < 0.05) and there was a relationship between community attitudes and efforts to prevent Schistosomiasis disease with p-value = 0.003 (where p < 0.05). The conclusion of the study were there is a significant relationship between knowledge and attitudes of the community with efforts to prevent Schistosomiasis in the Public Health Care Center of Wuasa. Suggestions to the health workers in the work area of health care center to increase local community awareness in supporting the prevention of Schistosomiasis disease.Keywords: Knowledge; attitude; prevention; Schistosomiasis.

Oil palm cultivation critically affects sociality in a threatened Malaysian primate

Human-induced habitat alterations globally threaten animal populations, often evoking complex behavioural responses in wildlife. This may be particularly dramatic when negatively affecting social behaviour, which fundamentally determines individual fitness and offspring survival in group-living animals. Here, we provide first evidence for significant behavioural modifications in sociality of southern pig-tailed macaques visiting Malaysian oil palm plantations in search of food despite elevated predation risk. Specifically, we found critical reductions of key positive social interactions but higher rates of aggression in the plantation interior compared to the plantation edge (i.e. plantation areas bordering the forest) and the forest. At the plantation edge, affiliation even increased compared to the forest, while central positions in the macaques' social network structure shifted from high-ranking adult females and immatures to low-ranking individuals. Further, plantations also affected mother–infant relationships, with macaque mothers being more protective in the open plantation environment. We suggest that although primates can temporarily persist in human-altered habitats, their ability to permanently adapt requires the presence of close-by forest and comes with a trade-off in sociality, potentially hampering individual fitness and infant survival. Studies like ours remain critical for understanding species’ adaptability to anthropogenic landscapes, which may ultimately contribute to facilitating their coexistence with humans and preserving biodiversity.

The Effect of Low Temperature on Physiological, Biochemical and Flowering Functions of Olive Tree in Relation to Genotype

Olive tree growth and reproduction are severely affected by temperature extremes, compromising fruit yield. In that aspect, the olive varieties “Koroneiki” and “Mastoidis” were employed in a mild cold stress experiment, imitating night frost incidents to assess their biochemical, physiological and reproductive functions in relation to genotype. The physiological performance of the stressed plants was not significantly altered, suggesting that both cultivars were well adapted to mild cold night stress. The biochemical response of the plants, regarding antioxidant enzymes, H2O2 and TBARS accumulation, confirmed that both cultivars could cope with the stress applied. The mRNA levels of the PPO gene, which participates in hydroxytyrosol biosynthesis and plant defense, were elevated after 24-h stress at 0 °C, in both cultivars with “Mastoidis” plants exhibiting higher levels for a longer period. Three more genes involved in hydroxytyrosol biosynthesis upregulated their expression levels as a response to cold stress. The numerous plant phenology aspects measured reinforced the conclusion that both cultivars responded to the stress applied. The results of the present study may contribute to better understanding olive tree adaptive responses to low temperature events, an abiotic stress condition that is often present in an open plantation, thus assisting farmers on breeding and cultivar selection.

Customizing unmanned aircraft systems to reduce forest inventory costs: can oblique images substantially improve the 3D reconstruction of the canopy?

ABSTRACT Photogrammetry makes it possible to estimate forest canopy surface at lower costs than light detection and ranging (LiDAR), which is considered the best data source to evaluate forest structure. Recent studies even suggest that points of forest understories can be obtained by means of unmanned aerial photogrammetry. However, little is known about how the characteristics of image sets, processing workflows, and forest openness affect understory point surveying. For forest inventories, unmanned aircraft systems (UASs) of fixed-wing type are preferred because they can survey large areas. It has been shown that the accuracy of UAS photogrammetry tends to increase by adding oblique images but acquiring them with fixed-wing UASs is challenging. To address this challenge, we proposed a multi-camera array for acquiring oblique images with fixed-wing UASs. To test our idea, we built two customized UAS and surveyed an open pine plantation and a tall deciduous forest with variable overstory density. The open plantation was selected for optimizing the measurement of reference canopy surface points using a terrestrial laser scanner. In the deciduous forest, we obtained reference understory points from a leaf-off photogrammetry survey. We confirm that including oblique images in the image set is a good practice for forestry applications. Using the UASs to test whether a multi-camera system is better than a single-camera system for acquiring nadir-oblique image sets, we conclude that the advantages are (1) more efficient acquisition of oblique images and (2) better understory modelling in open canopies. The multi-camera acquisition of oblique images increases the understory point density, making the estimation of crown cover percentage and maximum canopy height more accurate, by 33% and 50%, respectively.

Bird community response to landscape and foliage arthropod variables in sun coffee of central Kenyan highlands

Land conversion represents a serious threat to terrestrial biodiversity and effective conservation in human-dominated landscapes requires an understanding of the relationship between spatial heterogeneity and biodiversity. Coffee is the most valuable tropical export in the world with the capacity to affect biodiversity on a large scale, and much of the world's coffee is grown in open plantations (sun coffee), where little research has documented how landscape structure or food availability affect bird diversity. We examined the effects of both landscape characteristics and foliage arthropod abundance on bird species richness, total bird abundance and the abundance of foraging guilds in sun coffee plantations of central Kenyan highlands. Variation in the local landscape appeared to have little effect on bird abundance, while the foliage arthropod community, particularly number of arthropod orders, may have a strong impact on omnivore and insectivore abundance in sun coffee. These results do not mean small scale fragments or landscape composition is unimportant to bird communities in our region for several reasons, including the high model uncertainty that may indicate an important missing variable, the habitat complexity and presence of large forest reserves around our study sites, and the single scale at which our variables were tested. Our results indicate that farm managers wanting to increase bird abundance, especially omnivores and insectivores, should consider balancing the need to eradicate coffee pests and leaving an intact arthropod community that likely increases these guilds. Further study is needed to validate these patterns, which may have strong implications for bird biodiversity in agricultural settings across other areas in eastern Africa.

Herpetological diversity across intact and modified habitats of Nosy Komba Island, Madagascar

ABSTRACTA six month herpetological survey was undertaken between March and September 2015 on Nosy Komba, an island off of the north-west coast of mainland Madagascar which has undergone considerable anthropogenic modification. A total of 14 species were found that have not been previously recorded on Nosy Komba, bringing the total island diversity to 52 (41 reptiles and 11 frogs). The species assemblage, richness and abundance of four distinct habitat types were compared: closed-canopy forest, disturbed-canopy forest, shade-grown coffee plantation and mixed open plantation. The anthropogenic habitats on Nosy Komba were found to be of high conservation value for reptile species, where species richness and abundance found during surveys was equal to or higher than closed-canopy forest. By contrast, the abundance and species richness for frogs was reduced in anthropogenic habitats, especially in sun-exposed plantations. The forested areas of Nosy Komba contain twelve IUCN threatened species (9 reptiles and 3 frogs). Of these, Uroplatus henkeli, Uroplatus ebenaui, Phelsuma seippi, Zonosaurus subuniclor, Stumpffia psologlossa and Stumpffia pygmaea were also found in shade-grown coffee plantations, demonstrating the conservation value of these anthropogenic environments. Five threatened species on Nosy Komba were found exclusively in forested areas: Brookesia minima, Brookesia ebenaui, Lygodactylus madagascariensis, Rhombophryne testudo and Thamnosophis stumpffi. Our surveys demonstrate the importance of Nosy Komba for conserving regionally endemic and threatened species, and the often under-appreciated value of anthropogenic environments in species conservation, when also coupled with the protection of primary forest.

Movement patterns of selected insect groups between natural forest, open land and rubber plantation in a tropical landscape (southern Yunnan, SW China)

In many regions of tropical Asia, the expansion of rubber monoculture plantations is conducted by replacement of natural forest areas and strongly affects biodiversity and movement patterns of wild species, including insects. Against this background, we conducted a study on selected insect groups (longhorn beetles, bark beetles, wild bees and hoverflies) along transects between rainforest patches, open uncultivated land and rubber plantation habitats in a region of Xishuangbanna (southern Yunnan, China), with the objectives to identify (a) movement directions and patterns of selected insect groups based on their abundances in modified Malaise traps in the different habitats, and (b) the role of remaining natural rainforest patches and rubber plantations, respectively, for insect diversity maintenance and conservation. The highest total numbers of species and individuals of bark beetles, longhorn beetles and wild bees were recorded from the natural forest edge compared to open land and rubber plantation edge. This result clearly indicates that the natural forest plays an important role in maintenance of these three insect groups. However, the highest number of hoverfly species and individuals was recorded from the open land sites, indicating the most relevant habitat type for this group of species. Overall, the lowest species and individual numbers were recorded from the rubber plantation edge, indicating the unsuitability of this habitat type for all insect groups considered. The distribution of species and individuals in the opposite trap sides along the transect indicates that longhorn beetles, bark beetles and wild bees show not only movements from the forest to the surrounding habitats, but also return back after encountering the unsuitable rubber plantation habitat. Bark beetle composition showed the relatively highest similarity between all trap sites and opposite trap sides among the insect groups considered, indicating a higher movement activity than the other groups. The four insect groups considered in this study show different movement modes between the forest, open land and rubber plantation, which are not the same for all taxa. Except for hoverflies, the natural forest was found to be the most important habitat for the maintenance of species diversity in the different land use types of the study area.

Influence of neighbouring woody treatments on Mediterranean oak development in an experimental plantation: Better form but weaker growth

Mixed plantations have been receiving increasing attention for their documented or supposed potential benefits over monospecific plantations. In particular, the use of neighbouring (or nurse) vegetation around target plants can enhance their performance through limitation of the competing herb layer, and can also improve their morphology.Here we examine the benefits and drawbacks of using neighbour treatments on the response of target trees in open plantations. We set up an experimental plantation in southern France, in which two co-occurring target oak species (the evergreen Quercus ilex and the deciduous Quercus pubescens) were introduced in different neighbour treatments using a tree (Pinus halepensis) and a shrub species (the nitrogen-fixing Coronilla glauca). Oaks were planted with pine neighbours at two densities, with shrub neighbours, in a mixture of pines and shrubs or without neighbours. The ground vegetation was either regularly weeded or left to grow in order to detect any indirect facilitation interactions. Target oak responses (survival, growth, and morphology) were monitored over 7years. Soil water content and light availability were also measured throughout the experiment.We found competition to be the dominant process driving interactions between neighbours and target tree species. Growth was reduced by neighbour treatments for both species, but more in weeded than in unweeded treatments, showing an alleviation of competitive interactions by neighbours through limitation of herb layer development. However, in both ground vegetation treatments, growth was severely reduced with Coronilla shrubs. Survival was only significantly impaired for the less shade-tolerant Q. pubescens oak used in combination with shrubs. The negative influence of the neighbour treatments was mainly attributable to light interception, which was particularly high by shrub canopy. Soil moisture was also slightly reduced by shrub neighbours, but it remained high with pines in the unweeded treatment owing to a limited abundance of herbs. However, stem form was improved by the neighbour treatments: oaks developed narrower crowns and greater slenderness with neighbours, whereas oaks in the open showed a bushy morphology. These findings emphasise the need to clearly identify key objectives before implementing mixed plantations (e.g. maximising growth, survival, improving morphology, etc.) and to use active management to control potential undesirable effects of the neighbouring vegetation on target plants.

Numerical taxonomy on varieties of Adansonia digitata L.

Variations in the morphological features of Adansonia digitata L. were studied, which may be used for the delimitation of varieties in the species. The wide range of uses of these naturalised trees in the world have in recent time witnessed increasing demand of their foliar, bark, root, fruit and seed products in nutritional, fibre and medical applications. The upsurge demand for these products needs to be balanced with new varieties of improved performance to meet the supply chain. To achieve this, the present study was aimed at setting the foundation of variability analysis based on morphological features to detect promising varieties for mapping out of future breeding schemes of this multi-purpose tree. The fresh specimens were collected in open vegetation, plantations, houses and bushy areas from mature plant stands in Sudan and Guinea savannah of Nigeria. Both qualitative and quantitative characters studied, coded and subjected to cluster analysis. Some morphological characters indicated close affinity amongst the varieties of A. digitata. Features of taxonomic importance amongst the varieties of A. digitata include leaf surface, pod surface, leaf stalk surface, pod surface, pod end form, pod colour, pod size, stalk size, number of seed per pod, leaf size, seed size, occurrence of leaflet number and leaflet size. Within the species, there is evidence indicating the existence of a number of local types differing in habit, vigour, size, and quality of the fruits and vitamin content. These features were considered to be taxonomically relevant in the delimitation of these varieties. Numerical analysis of the qualitative and quantitative characters data using cluster analysis – average linkage, single linkage, complete linkage and centroid methods delimit all the Operational Taxonomic Units (OTUs) into four varieties hence, infraspecific classification of A. digitata is hereby proposed.

Testing indicators of biodiversity for plantation forests

In many parts of the world, plantations make up a considerable proportion of the total forest area. In such regions, the identification of high biodiversity value stands and of management practices to enhance biodiversity is essential if the goals of Sustainable Forest Management are to be achieved. Since complete biodiversity assessments are rarely possible, efforts have been increasingly focussed on the use of indicators. Of particular interest are indicators applicable to individual stands that require no specialist taxonomic or technical knowledge to assess. Candidate biodiversity indicators had been identified in a previous study using data from Irish Sitka spruce (Picea sitchensis) and ash (Fraxinus excelsior) plantations but had yet to be tested on independent data. In the present study, the provisional indicators for vascular plant, bryophyte, spider and bird diversity were tested on data from Irish Scots pine (Pinus sylvestris), oak (Quercus petraea/Quercus robur), Sitka spruce and lodgepole pine (Pinus contorta) plantations. Conifer canopy cover was confirmed as an important biodiversity indicator, due to its influence on below-canopy microclimatic and structural conditions. Bryophyte species richness was higher in relatively high canopy cover plantations on poorly drained soils, while bird species richness was higher in more open plantations with high shrub cover. Coarse woody debris was an important substrate for forest-associated bryophytes, with higher species richness at higher volumes of deadwood. Both proximity to old woodland and stand age were confirmed as positive indicators for forest-associated vascular plants. This is related to dispersal limitation in these species, with nearby woodlands acting as important seed sources and colonisation increasing with time. Stand age was also confirmed as a positive indicator for forest-associated spiders and is related to the development of suitable habitat as the plantation matures. All of the confirmed indicators can be assessed without need for specialist knowledge, are ecologically meaningful and applicable to a range of forests managed under a clearfelling system. They can be used to assess the potential value of stands for the taxonomic groups to which they apply, as well as giving insights into management practices to enhance diversity in these groups.

Influencia de la pérdida foliar sobre la cosecha en el cv. Gruesa, Musa acuminata Colla (AAA), cultivado bajo invernadero en las Islas Canarias

El cultivo de la variedad de platanera Gruesa, selección local de Dwarf Cavendish, ha experimentado un importante aumento en los últimos años en las Islas Canarias, tanto al aire libre como bajo invernadero. La eliminación de hojas, tras la floración, es una práctica habitual en los cultivos bajo invernadero. Asimismo es frecuente la pérdida de hojas por el efecto de los vientos en los cultivos al aire libre. El objetivo de este trabajo es evaluar, mediante simulación de pérdida foliar por daños mecánicos, la influencia que tiene la disminución de superficie foliar sobre el llenado y cosecha de la fruta en dicho cultivar. Para ello, cuatro meses antes de la cosecha se efectuaron cinco niveles de defoliación: 0%, 25%, 50%, 75% y 100%. Se valoran dos métodos diferentes de defoliación, eliminación de limbo foliar y tronchado de hojas con posterior corte de éstas. Se analizan y presentan datos morfológicos, fenológicos y productivos, así como valoración de la metodología empleada en este trabajo para la simulación de daños. A partir de un 25% de defoliado, equivalente a 7.5 hojas funcionales por planta, se detectaron diferencias significativas con las plantas testigos.

Photosystem II functionality and antioxidant system changes during leaf rolling in post-stress emergingCtenanthe setosaexposed to drought

We studied the changes in antioxidant system and chlorophyll fluorescence parameters in post-stress emerging Ctenanthe setosa (Rosc.) Eichler (Marantaceae) plants (PSE plants) having reduced leaf area under drought stress causing leaf rolling and re-watering. PSE plants were compared to primary stressed plants (PS) in previous studies. The parameters were measured at different visual leaf rolling scores from 1 to 4 (1 is unrolled, 4 is tightly rolled and the others is intermediate form). Water potentials and stomatal conductance of leaves were gradually decreased during leaf rolling. Similarly, maximum quantum efficiency of open PS II center and quantum yield of PS II decreased during the rolling period. Non-photochemical quenching of chlorophyll fluorescence decreased at score 2 then increased while photochemical quenching did not change during leaf rolling. Electron transport rate decreased only at score 4 but approximately reached to score 1 level after re-watering. Superoxide dismutase activity was not constant at all leaf rolling scores. Ascorbate peroxidase, catalase and glutathione reductase activities generally tended to increase during leaf rolling. Lipid peroxidation and H 2 O 2 content increased at score 2 but decreased at the later scores. On the other hand, O 2 .- production increased during the rolling period. After re-watering of the plants having score 4 of leaf rolling, antioxidant enzyme activities were lower than those of score 1. Other physiological parameters also tended to reach the value of score 1. The results indicated that PSE plants gained drought tolerance by reducing leaf area effectively induced their antioxidant systems and protected the photosynthesis under drought stress similar to PS plants.

Predation on artificial ground nests in birch forests fragmented by spruce plantations

Spruce planting (Picea abies) in coastal birch forests (Betula pubescens) of northern Norway could influence ground-nesting species such as willow ptarmigan (Lagopus lagopus) and black grouse (Tetrao tetrix). Predator-specific predation rates on baited trackboards were therefore studied in 3 successional edge gradients: birch forest adjacent to (1) closed spruce plantations, (2) open spruce plantations, and (3) clearings. We also examined the influence of 2 types of landscapelevel variables on predation rates: the distance from sampling location to the nearest roads and buildings and the land use composition within a 1-km radius of the sample. Predation rates were dominated by 2 generalist species: red fox (Vulpes vulpes) (19.2%) and hooded crow (Corvus corone cornix) (7.5%). Predation appears dependent on the successional stage of spruce plantations, with areas near clearings (63.5%) and open spruce plantations (59.8%) experiencing higher predation pressures than closed spruce plantations (45.3%). However, predation rates were highly variable among landscape blocks. Neither landscape nor vegetation variables could explain this block-level variation. We discuss alternative mechanisms that could explain differences between landscape blocks, but further studies are needed to understand the spatial heterogeneity of predators at larger scales.

Habitat preferences and seasonal activity of the Microstigmatidae from Ngome State Forest, South Africa (Arachnida: Araneae)

As part of the South African National Survey of Arachnida (SANSA) inventories are underway to determine the arachnid biodiversity of various biomes. Asurvey of groundliving spiders was conducted over a year period (1992-1993) at Ngome State Forest, KwaZulu-Natal, South Africa. Spiders were collected with 180 pitfall traps from five different habitat types ranging from indigenous forest to a pine plantation and grassland. A total of 186 specimens of the rare Mygalomorphae family Microstigmatidae were sampled, representing 2 % of the total spider fauna collected during the study. Two species, Microstigmata longipes (Lawrence) and M. zuluensis (Lawrence), occur sympatrically. Both species were more active in the indigenous forest, and were absent or present in low numbers in the open grass and pine plantation. Microstigmata zuluensis was slightly more abundant (59 % of total) and was recorded from three of the five habitats, while M. longipes (41 %) was found in four of the habitat types. Both species were active throughout the year with the lowest numbers recorded in winter (June to August). The males of M. longipes peaked in November while those of M. zuluensis peaked in April.

Effects of pine silviculture on the ant assemblages (Hymenoptera: Formicidae) of the Patagonian steppe

In NW Patagonia, forestry with rapid growing species is an expanding practice, especially in the semi-arid steppe. To provide data for managing forests for biodiversity, we studied the impact of forestry on the native ant assemblages. We sampled ants using pitfall traps in a wide geographical area, including steppe sites and pine plantations, both dense (forest cover 87% in average) and sparse (forest cover 52% in average) designs. We measured and analyzed ant abundance, species richness and species composition as response variables. Through our results, we show that ants are highly sensitive to pine tree forests. Ant abundance within plantations is lower and species composition significantly impoverished. However, the more open plantations sustained ant assemblages which resemble those of the native steppe samples. This is probably because the open forests allow for native under-story vegetation to grow as in the natural steppe sites. We suggest that tree presence in an otherwise shrub and grass dominated area is responsible for the changes in the ant assemblages. We also note that the presence of native vegetation cover predicts ant assemblage composition in these arid zones. From an applied point of view, our findings suggest that a more open plantation design will be accompanied by higher ant abundances and species richness, which in turn may bring about consequences for sustainable forest management in the area.

Survival and growth of black and white spruce seedlings in relation to stock type, site preparation and plantation type in southeastern Manitoba

Differences in survival and growth of black and white spruce seedlings planted on boreal mixedwood sites were tested for stock types (transplant versus container), site preparation (Donaren disc trenching versus no trenching), and plantation types (open versus sheltered) in southeastern Manitoba after eight or nine growing seasons. Mortality of open plantation (32.3%) and container stock (32.5%) were significantly higher than sheltered plantation (23.7%) and transplant stock (22.8%), respectively. Donaren trenching slightly reduced the mortality of black spruce but significantly increased the mortality of white spruce. Seedlings of container stock (110 cm) were significantly shorter than transplant stock (157 cm). Significant difference in height was found between open and sheltered plantations for black spruce but not for white spruce. Root collar diameter of container stock (15.6 mm) was significantly smaller than transplant stock (23.1 mm). Root collar diameter in sheltered plantations was significantly larger than that in open plantations for black spruce but not for white spruce. Black spruce open plantation had significantly smaller volume (97 cm3) compare to black spruce sheltered (210 cm3) and white spruce open (175 cm3) and sheltered (229 cm3) plantations. White spruce open plantations also had smaller volume than white spruce sheltered plantations. Container stock had smaller volume (89 cm3) than transplant stock (267 cm3). For transplant stock, strip plantations had a significantly higher volume (329 cm3) than open plantations (204 cm3). Based on above results, we recommend that (1) transplant stock should be used, (2) sheltered plantation site preparation should be used on boreal mixedwood sites, and (3) Donaren disc-trenching is not necessary for planting white spruce. Key words: silviculture, boreal mixedwood site, plantation

Changes in Nightjar Caprimulgus europaeus populations in upland forests in Yorkshire

The Nightjar populations of Yorkshire's upland forests have grown significantly during recent years, probably as a result of a concurrent increase in the available area of suitable habitat due to forest management. In common with other populations it appears that the birds utilize younger, more open plantations. Comparison, based on discriminant analysis, of the habitat characteristics of forest plantations occupied and unoccupied by Nightjars suggests two things. First, that birds are more likely to occupy larger rather than smaller clearings and, second, that the study populations are close to their maxima. However, with continuing rotational felling, the area should continue to support a similar population.

MAPPING VEGETATION AND EROSION CHANGES ON THE NORTHERN SLOPES OF TABLE MOUNTAIN USING MULTI-TEMPORAL AERIAL PHOTOGRAPHY AND GIS, 1944–1992

ABSTRACT Eight sets of sequential aerial photographs taken between 1944 and 1992 were used to assess vegetation and erosion changes on the northern slopes of Table Mountain, Cape Town, South Africa. A vector-based Geographic Information System facilitated the generation of maps and statistical analysis of spatial data. The results show that over this 48 year period, the vegetation class shrubland without trees increased from 36% to 73% of the total area. By contrast, closed and open canopy plantations of alien trees decreased from 13% to 8%, and from 29% to 4% respectively. The time-series of erosion maps displayed a high degree of variability but revealed that certain areas of the mountain slopes are prone to accelerated soil erosion. Nonparametric statistical methods were used to ascertain whether certain erosion features have a predictive relationship with particular vegetation cover classes.