Khaya Anthotheca Research Articles

Impacts of Selective Logging and Agricultural Clearing on Forest Structure, Floristic Composition and Diversity, and Timber Tree Regeneration in the Ituri Forest, Democratic Republic of Congo

Mature tropical forests at agricultural frontiers are of global conservation concern as the leading edge of global deforestation. In the Ituri Forest of DRC, as in other tropical forest areas, road creation associated with selective logging results in spontaneous human colonization, leading to the clearing of mature forest for agricultural purposes. Following 1–3 years of cultivation, farmlands are left fallow for periods that may exceed 20 years, resulting in extensive secondary forest areas impacted by both selective logging and swidden agriculture. In this study, we assessed forest structure, tree species composition and diversity and the regeneration of timber trees in secondary forest stands (5–10 and ∼40 years old), selectively logged forest stands, and undisturbed forests at two sites in the Ituri region. Stem density was lower in old secondary forests (∼40 years old) than in either young secondary or mature forests. Overall tree diversity did not significantly differ between forest types, but the diversity of trees ≥10 cm dbh was substantially lower in young secondary forest stands than in old secondary or mature forests. The species composition of secondary forests differed from that of mature forests, with the dominant Caesalpinoid legume species of mature forests poorly represented in secondary forests. However, in spite of prior logging, the regeneration of high value timber trees such as African mahoganies (Khaya anthotheca and Entandrophragma spp.) was at least 10 times greater in young secondary forests than in mature forests. We argue that, if properly managed and protected, secondary forests, even those impacted by both selective logging and small-scale shifting agriculture, may have high potential conservation and economic value.

First report of Conchaspis cordiae (Hemiptera: Conchaspididae) in Florida and the united states

We report for the first time the presence in Florida and the continental United States of Conchaspis cordiae Mamet (Hemiptera: Sternorrhyncha: Conchaspididae) (Fig. 1), an adventive scale insect species from the West Indies. Conchaspis cordiae was described by Mamet (1954) from specimens collected in 1919 on black sage (Cordia sp.), and in 1917 from on St. Croix, U.S. Virgin Islands. It was reported also from West Indies mahogany (Swietenia mahagoni Jacquin) and seagrape (Coccoloba uvifera L.) in the Dominican Republic (Panis and Martin 1976), and has been collected in Puerto Rico and Haiti (Douglass R. Miller, personal communication). It has not been reported as a pest, and nothing is known about its biology. Florida Department of Agriculture and Consumer Services inspector Ms. Lynda Davis made the first U.S. collection of C. cordiae on West Indies mahogany on November 26,2003, in Hialeah (Miami-Dade County, FL). On February 8, 2005, Ms. Jeanette Wofford, Arborist, Department of Public Works, Cooper City, FL, called the attention of the senior author to extensive infestations of scale insects on West Indies mahoganies in Cooper City. Specimens collected from both these cities were identified as C. cordiae by the second author. Having determined that it was possibly a serious pest, we conducted a preliminary survey in urban areas from Miami-Dade County to a site about 70 km north of this in southern Palm Beach County, examining West Indies mahoganies from the ground at 16 sites where at least 10 of these trees were in close proximity. Infested branches as high as 8 m from the ground were pruned with a pruning pole for obtaining specimens. Trees with infestations that we could not see or collect specimens from, i.e., restricted to branches higher than 8 m, were thus excluded from the survey. Specimens of C. cordiae from each locality were mounted on microscope slides and their identifications confirmed by the second author. Based on these observations, at least one West Indies mahogany was infested with C cordiae at 62.5% of the 16 sites examined, including the northernmost (26?22'N) and southernmost (25?45'N) and the easternmost and westernmost sites (80?07'W and 80?25'W, respectively) (Table 1). To compare West Indies mahogany and several closely related species as potential hosts of this scale insect, we examined mature trees of species in the family Meliaceae at the Fort Lauderdale Research and Education Center in Davie, FL. These included 196 West Indies mahoganies, and trees interspersed with them including 14 Honduras mahoganies (S. macrophylla King), 29 mahogany hybrids (S. macrophylla x S. mahagoni), four African mahoganies (Khaya nyasica [Stapfl ex Baker f.), two tropical-cedars (Cedrela odorata L.), and two neem trees (Azadirachta indica A. Jussieu). These observations provided two indications that West Indies mahoganies and the S. macrophylla x mahagoni hybrid are preferred hosts: (1) Infestations were found on 40.8% of the West Indies mahoganies, and 41.3% of the S. macrophylla x mahagoni hybrids, compared with 14.2% of the Honduras mahoganies, and (2) Large patches of dense populations of up to 30 mature female C. cordiae per cm2 along with numerous first and second instars were visible on branches of most of the infested West Indies mahoganies and the macrophylla x mahagoni hybrids. In contrast, infestations on Honduras mahoganies were sparse and consisted of relatively few individuals per tree. One of the African mahoganies was lightly infested. No scale insects were found on Spanishcedar or neem trees. Conchaspis cordiae was observed on bark and not on other plant parts such as leaves or fruit capsules. Infestations were concentrated on twigs and branches up to about 6 cm in dia. Only occasional scale insects were observed on larger branches and main trunks, where they occurred in bark fissures. Conchaspididae with about 30 described species is a small tropical family related to Diaspididae. Previously, two species have been reported in Florida: (1) Conchaspis angraeci Cockerell, native to the Caribbean and found on orchids and other ornamental plants (Merrill & Chaffin 1923), and (2) Asceloconchaspis milleri Williams,

Effects of Light Gaps and Litter Removal on the Seedling Performance of Six African Timber Species1

ABSTRACTValuable timber tree species frequently show poor regeneration after selective logging in tropical forests. Small size of logging gaps, lack of soil disturbance, and limited seed availability have each been blamed for observed regeneration failures. We investigated seed germination and seedling performance using a split‐plot factorial design involving light availability and litter removal for six Central African timber tree species, hypothesizing that canopy gaps and litter removal would improve seedling establishment, and that less shade‐tolerant species would show stronger responses to both factors. Contrary to our expectations, significantly more germinants established on intact litter than on exposed mineral soil 3 mo after seeding. After 18 mo, seedling survival, height and diameter growth, leaf area, and rooting depth were all much higher in gap plots than in the understory for all species, with the exception of Gilbertiodendron dewevrei, a highly shade‐tolerant species whose survival was higher in the understory. Leaf production was negatively influenced by litter removal in the least shade‐tolerant species, Nauclea diderrichii, with weak or positive effects in other species. G. dewevrei, while displaying a low‐light threshold for growth, exhibited a surprisingly high growth response to increasing light comparable to more shade‐intolerant species, a response that may help explain its local competitive dominance in the region. Due to the rapid closure of small gaps, we suggest that shade‐intolerant species such as N. diderrichii, Khaya anthotheca, and Entandrophragma utile might benefit from more intensive silvicultural practices that create larger canopy gaps.

Four tetranortriterpenoids from the stem bark of Khaya anthotheca

Eight limonoids, anthothecanolide ( 1), 3- O-acetylanthothecanolide ( 2), 2,3-di- O-acetylanthothecanolide ( 3), 6 R,8α-dihydroxycarapin ( 4), 3β-acetoxy-3-deoxo-6 R-hydroxycarapin ( 5), methyl angolensate, methyl 6-hydroxyangolensate and khayalactone together with sitosterol glucoside, have been isolated from the extracts of the stem bark of Khaya anthotheca. Compounds 1– 4 are described for the first time. Their structures were established by analysis of the high-field NMR and MS data. The structure of compound 4 was confirmed by a single crystal X-ray structure analysis.

Growth performance and management of a mixed rainforest tree plantation

Monoculture plantations of Pinus, Eucalyptus and Acacia have been established oil rainforest lands throughout the world. However, this type of reforestation generally supplies low quality timber and contributes to landscape simplification. Alternatives to exotic monoculture plantations are now beginning to gain momentum with farmers and landholders attempting to establish a variety of rainforest trees in small plantations. When compared to the well studied commercial species, knowledge concerning the growth and management of many of these rainforest species is in its infancy. To help expand this limited knowledge base an experimental plantation of 16 rainforest tree species in a randomised design was established near Mt. Mee, in south-eastern Queensland, Australia. Changes in growth, form (based on stem straightness, branch size and branchiness), crown diameters and leaf area of each species were examined over 5 years. Patterns of height growth were also measured monthly for 31 months. Species in this trial could be separated into three groups based on their overall growth after 5 years and their growth patterns. Early successional status, low timber density, high maximum photosynthetic rates and large total leaf areas were generally correlated to rapid height growth. Several species (including Araucaria cunninghamii, Elaeocarpus grandis, Flindersia brayleyana, Grevillea robusta and Khaya nyasica) had above average form and growth, while all species in the trial had considerable potential to have increased productivity through tree selection. As canopy closure occurred at the site between years four and five, growth increments declined. To reduce stand competition a number of different thinning techniques could be employed. However, simple geometric or productivity based thinnings appear to be inappropriate management techniques for this mixed species stand as they would either remove many of the best performing trees or nearly half the species in the trial. Alternatively, a form based thinning would maintain the site's diversity, increase the average form of the plantation and provide some productivity benefits.

Acylperoxylated and seco-Mexicanolides from Stems of Khaya anthotheca

The stems of Khaya anthotheca yielded two new limonoids, which were identified on the basis of spectroscopic analysis as 1alpha,8alpha-oxido-3beta-acetoxy-2alpha-acylperoxy-1alpha,14alpha-dihydroxy-[3.3.1(10,2)]-bicyclomeliac-7,19-olide (3) and 3-acetoxy-8,14-dien-8,30-seco-khayalactone (4). Methyl 1alpha,2beta,3alpha,6,8alpha,14beta-hexahydroxy-[4.2.1(10,30).1(1,4)]-tricyclomeliac-7-oate, scopoletin, and 3-O-beta-D-glucopyranosylsitosterol were also isolated. The limonoids were of little value to clarify the basis of the nonresistance against Hypsipyla grandella.

Dispersal limits natural recruitment of African mahoganies

The abundance of forest tree species may be locally limited by the inability of species to disperse to all sites suitable for germination and establishment. This phenomenon of “dispersal limitation” has been suggested to promote the maintenance of high species diversity in tropical forests by slowing down competitive exclusion. We present the first direct experimental evaluation of dispersal limitation in tropical forests, and of its importance relative to other factors affecting recruitment. Seed addition, litter removal and light availability effects on seedling establishment were evaluated in a full factorial experiment on two African mahogany species, Entandrophragma utile and Khaya anthotheca. Seedling recruitment after 18 months, was ∼22 times greater in seed addition treatments (with addition rates corresponding to the tail of seed shadows of large reproductive trees) compared to controls. This seed addition effect was an order of magnitude greater than either gap or litter removal effects, with similar results observed in both logged and primary forest locations. We conclude that dispersal limitation strongly limits seedling establishment for the two species studied. An important “applied corollary” of this result is that seed supplementation may substantially increase local abundance of valuable or rare species in disturbed or managed tropical forests.

L'efficacité anthelminthique de quelques plantes indigènes dans la province du Nord-Ouest au Cameroun

Des expériences ont été faites sur neuf groupes de huit veaux pour déterminer l’efficacité anthelminthique de quatre plantes indigènes : Terminalia glaucescens, Vernonia amygladina, Solanum aculeastrum et Khaya anthotheca. Des échantillons de fèces de veau ont été récoltés aux jours 0, 7, 14, 21, 28, 35 et 42 pour effectuer la numération des œufs par la technique sur lame de McMaster. Les résultats ont montré que Solanum aculeastrum, Khaya anthotheca and Vernonia amygladina étaient efficaces avec des réductions de I’excrétion des œufs respectivement de 34,4, 55,8, et 52,4 % à doses complètes, 21 jours après le traitement.

Biodiversity and Human Activities in the Udzungwa Mountain Forests, Tanzania. 1. Ethnobotanical Survey in the Uzungwa Scarp Forest Reserve

ABSTRACT An ethnobotanical survey was conducted between March and September 1997 in the northwestern and southern parts of the Uzungwa Scarp Forest Reserve using strip transects. Altogether 489 plant species from 107 families were recorded, most of them trees (37 %) and shrubs (27 %). Others were lianas, herbs, ferns and parasites. Endemic plants restricted to the Udzungwa Mountains and Eastern Arc endemic plants not restricted to the Udzungwas were present. It was established that local communities around the forest highly depend on the natural forests for forest products. Most human uses were for traditional medicine, fuelwood and building materials. Quality hardwoods Khaya anthotheca, Afzelia quanzensis, Milicia excelsa and Ocotea usambarensis were noted. To reduce the pressure on the natural forest, agroforestry is recommended in the area to meet some of the people's needs for forest products, thereby contributing to the conservation of biodiversity. It is also important to do more intensive surveys i...

Seasonal Fluctuations and Diversity of Bark and Wood-boring Beetles in Lowland Forest: Implications for management Practices

SYNOPSIS The phenology and diversity of wood-living beetles attacking Cedrela mexicana, Khaya nyasica and Milicia excelsa were observed for one year with weekly window-flight-trap collections. A total of 150 species (10 known to be common pests of timber) were collected, most of them occurring yearround and a few indicating seasonal fluctuations in abundance. The flight patterns and low catches depicted by some primary attackers could have some management implications in Kimboza or similar areas.

Nutrients and mass in litter and top soil of ten tropical tree plantations

The importance of litter to nutrient and organic matter storage and the possible influence of species selection on soil fertility in ten stands each consisting of a separate tree species were examined in this study. The plantations had been grown under similar conditions in an arboretum in the Luquillo Experimental Forest, Puerto Rico. The species involved were: Anthocephalus chinensis, Eucalyptus × patentinervis, E. saligna, Hernandia sonora, Hibiscus elatus, Khaya nyasica, Pinus caribaea var. hondurensis, P. elliottii var. densa, Swietenia macrophylla, and Terminalia ivorensis. After 26 yr, litter mass ranged from 5 mg ha-1 in the H. sonora stand to 27.2 Mg ha-1 in the P. caribaea stand. Nutrients in the litter (N, P, K, Ca, and Mg) also varied widely, but stands were ranked in different order when ranked by nutrients in the litter than then ranked according to accumulation of mass. Only E. saligna and A. chinensis stands were ranked similarly in accumulation of both nutrients and mass, and the stand of H. elatus was ranked higher with respect to nutrient accumulation than to accumulation of mass. The nutrient concentration in standing leaf litter generally increased in the order of recently fallen <old intact< fragmented. Nutrient concentration of standing leaf litter appears to increase with age and depth in the litter layer. The amount of nutrients stored in the litter compartment of these plantations was in the same order of magnitude as the quantity of available nutrients in the top 10-cm of mineral soil. Total litter mass was negatively correlated with the mass-weighted concentration of N, K, and Mg. The same relationship was found for Ca in the leaf litter and N in the fine wood litter compartments. In some stands (notably P. caribaea, P. elliottii, and E. saligna), leaf litter derived from species other than the species planted in that particular stand had higher nutrient concentration than leaf litter from the planted species. Soils of the 10 stands were classified in the same soil series and had similar texture (clay soils). However, significantly different chemical characteristics were found. Results obtained by analysis of covariance and by limiting comparisons to adjacent stands with similar soil texture, indicate that different species have had different influences on the concentration of available nutrients in soil.

Bioecological Aspects of the Mahogany Defoliator Heteronygmia dissimilis in Morogoro, Tanzania

Various aspects of the morphology, life cycle and several natural enemies of Heteronygmia dissimilis, a lymantriid defoliator of African mahogany, Khaya nyasica, were studied in Morogoro, Tanzania. This insect is a multivoltine species with at least four overlapping generations a year, all stages of which can be found from March to October. November to February are apparently spent in pupal aestivation. The September/October generation completed its life cycle from egg to adult in an average of 41 and 45 days for males (five moults) and females (six moults), respectively. On the average females produced 200 eggs. Larvae occurred in two colour variations. They are generally nocturnal feeders, skeletonizing leaflets while in the early instars and resting on foliage or bark during the day. Adults exhibit sexual dimorphism in terms of size, colour and shape. The sex factor was close to 0.5. Four species of hymenopterous parasites belonging to four families (Chalcidae, Encyrtidae, Eurytomidae and Ichneu-monidae), as well as two species of dipterous parasites (Tachinidae) were obtained from eggs, prepupae and pupae of H. dissimilis. During the rainy season, the entomopathogenic fungus Paecilomyces farinosus was epidemic among pupae.

4. Establishment ofKhaya nyasicaPlantations

(1987). 4. Establishment of Khaya nyasica Plantations. South African Forestry Journal: Vol. 141, No. 1, pp. 4-4.

The Silviculture of Indigenous and Exotic Forest Trees other than Pines and Eucalypts in Malawi

SYNOPSIS Most of the work of the Department of Forestry for at least the first 30 years since its foundation in 1902 concentrated mainly on indigenous trees such as Widdringtonia nodiflora (Syn. W. whyteii), Pterocarpus angolensis and Khaya nyasica, just to mention a few examples. The emphasis started to change in the early 1930s when it was realised that the faster growing exotic species, mainly pines, could be grown under the local conditions and produce high returns of construction timber in a relatively shorter time than the indigenous species. Gradually the work on the indigenous trees was reduced to almost ad hoc silvicultural trials, mainly on the culturing methods of a few selected species. These were done in the form of unreplicated arboretum plots, although some replicated trials started to be established in the early 1960s. However, by this time, the exotic trees Pinus patula, P. elliottii, P. taeda and the Eucalyptus spp. had by far passed the experimental stage and had become the major plantation species in the country. Consequently attention was almost totally paid to these species and a number of the old indigenous trial plots were neglected or simply forgotten. This paper, therefore, merely lists some of the important indigenous trees of which the plots are still maintained and from which information, although sparse and broken, is available. Information on establishment and management techniques has also been given for each species wherever available.

The structures of three new meliacins isolated from Khaya anthotheca heartwood

Further examination of the light petroleum extract of the heartwood of Khaya anthotheca has led to the isolation of 24-methylenecycloartanol, a new compound C30H52O, azadirone (9), and three new meliacins in addition to the already reported anthothecol (1). The new meliacins have been shown to be 11β-acetoxyazadirone (10), 11α-acetoxyazadirone (11), and 1α,11:14β,15β-diepoxy-6-hydroxymeliaca-5,9,20,22-tetraene-3,7-dione (20) with a novel dihydrofuran ring. The 13C n.m.r. spectra of compound (20) and of related meliacins have been analysed.

The meliacins (limonoids): minor constituents of Khaya anthotheca: reduction of the meliacins with zinc–copper couple

The residues collected after isolation of anthothecol from Khaya anthotheca have afforded a new meliacin for which the structure (2b)(11β-acetoxyazadirone) is proposed. In addition, deacetylanthothecol and a sterol mixture shown by g.l.c. to consist of stigmasterol, β-sitosterol, campesterol, cycloeucalenol, and 24-methylenecycloartanol, were isolated. In the course of model experiments with anthothecol aimed at structural correlation with the new compound, zinc–copper couple was found to be a convenient and superior reagent for reduction of epoxides to olefins, αβ-unsaturated ketones to saturated ketones, and ketols and their acetates to ketones, in the meliacin series. By using this reagent new reduction products of anthothecol have been prepared and characterised.

Tetranortriterpenoids. Part XIV. The structure of nyasin, a limonoid from Khaya nyasica; a correction

Nyasin has been shown to be 11β-hydroxykhivorin (4) rather than an isomer of khivorin. This was confirmed by its preparation by partial hydrolysis of 11β-acetoxykhivorin (2).

Limonoids from Khaya anthotheca(Welw.) C.DC.

Khaya anthotheca occurs in two distinct chemical varieties. The timber of one, indigenous to East Africa, yields khivorin and a new compound identified as methyl 3β-isobutyryloxy-1-oxomeliacate, while the seeds yield khivorin, 3-deacetylkhivorin, and a new compound identified as 14β,15β-epoxy-16-oxo-1α,3α,7α-triacetoxy-meliacan. The second, indigenous to West Africa, lacks the characteristic lactones of other Khaya species. The timber contains anthothecol, while the seeds contain havanensin, deoxyhavanensin, and their acetates. An investigation has been made of the influence of the C-7 substituent on the course of the known acid catalysed isomerisation of havenensin.

Limonoids from Khaya nyasica Stapf. ex Bak.

Extraction of the timber of Khaya nyasica has given variable results. One sample has give nyasin, a new limonoid isomeric with khivorin, to which a stucture is assigned. Another sample has given mainly khivorin, 11β-acetoxy-khivorin and a number of minor constituents. Extraction of the seed has given the known limonoids khivorin, 3-deacetylkhivorin, and fissinolide, together with a new compond which appears to be the acetate of 3β-dihydro-carapin.

Dermatitis due to the wood dusts of Khaya anthotheca and Machaerium scleroxylon.

The causes of several cases of dermatitis at three furniture factories have been investigated. At two factories the trouble was traced to the wood of <i>Khaya anthotheca,</i> one of the species which comprise African mahogany. At the other factory the wood of <i>Machaerium scleroxylon,</i> a timber of similar appearance to Rio rosewood, was implicated. The relationship was established in each case by patch tests. Workers allergic to <i>K. anthotheca</i> reacted strongly to the constituent anthothecol whilst those allergic to <i>M. scleroxylon</i> were strongly sensitized by (R)-3, 4-dimethoxydalbergione and its related quinol.