E.T.F. Witkowski

POST-FIRE LITTER MICROSITES: SAFE FOR SEEDS, UNSAFE FOR SEEDLINGS'

We explore the effect of post—fire microsites on seed and seedling distribution and hence their potential role in community restoration. A summer wildfire and control burn in a sclerophyll shrubland in mediterranean Australia produced mosaics of physically and chemically contrasting microsites of litter and sand. Most seeds (>75%) of all species released from the burnt canopies fell, or were redispersed by wind, into the litter patches after both fires. Data on microsite characteristics and wind exposure (fire intensity), height of fruits, time of release, and seed properties were required to interpret relative distribution between the litter and sand patches. Seeds remained equally viable (up to 100%) over summer—autumn in the litter and sand and had equally high rates and levels (up to 100%) of subsequent winter germination. However, seedlings were 2—3 times less likely to survive in the litter and survivors were 35% smaller than those in the sand by the end of the first summer. Banksia hookeriana was particularly vulnerable to microsite properties, whereas the needle—leaved Hakea polyathema showed only minor responses. Pre—summer thinning of seedlings in the litter increased survival of the remainder by 2 times and size of the survivors by 31%. The fire—sensitive, small—seeded B. hookeriana had 17 times more seeds in the backburn litter than the resprouting, larger—seeded B. attenuata, which more than compensated for its 3 times greater seedling mortality levels over the dry summer. Recruitment of species prone to density—dependent mortality in the litter was enhanced by the retention of some seeds in the sand where competition for water was minimal, as indicated by the 2.2 times greater stomal conductance of their seedlings in early summer.

Effects of invasive alien acacias on nutrient cycling in the coastal lowlands of the Cape fynbos.

(1) Production, nitrogen and phosphorus return, and decomposition of leaf litter of the invasive alien, Acacia saligna, was compared with that of the indigenous sclerophyllous shrub, Leucospermum parile, in sand-plain lowland fynbos with acid soils low in P during the early stages of alien invasion. The same was done for A. cyclops and Pterocelastrus tricuspidatus in strandveld with alkaline soils high in P. (2) The Acacia spp. had twice the leaf N concentrations of the indigenous species, whereas P concentrations were highest in the strandveld species. (3) The Acacia spp. tended to produce more litter, with three times the N content of that of the indigenous species. No significant differences in P return were found, between the acacias and indigenous species in either vegetation. (4) Decomposition turnover times were longer in the fynbos species than those of the strandveld. Nitrogen was immobilized in the leaf litter of the indigenous species, while the N contents of the acacias varied little. Phosphorus was immobilized in the fynbos species compared with a release of about 50% from P. tricuspidatus after 2 years. (5) Soil N concentrations and litter-layer N contents were elevated under acacia canopies. (6) The N status of the fynbos and strandveld ecosystems is elevated by the invasion of alien acacias. The results for P cycling are equivocal and P availability does not appear to limit plant growth in the strandveld.

Unraveling the commercial market for medicinal plants and plant parts on the Witwatersrand, South Africa.

To unravel the market for commercial medicinal plants on the Witwatersrand in South Africa, a semiquantitative approach was taken. A stratified random sample of 50 herb-traders was surveyed, and an inventory of all plants and parts sold was compiled. Research participants were questioned on the scarcity and popularity of the plants traded, as well as suppliers and origins. The rarefaction method established that the sample size was adequate. The diversity of the sample was determined using ecological indices of diversity, and found to be comparatively high. In addition, Spearman rank correlations, chi-squared and Fisher’s exact probability tests were used to assess the probability of certain taxa being used. At least 46% of the taxa traded showed a higher than expected probability of being utilized, and taxa tended to be harvested from the largest families proximate to the markets. About 511 species are traded in the region, and there is a low dominance in the use of species. Ethnic and floristic diversity are influential in deciding the trading patterns that have emerged.RésuméPour découvrir le marché commercial des plantes médicinales et des parties de plantes, nous avons utilisé une approche semiquantitative. Un échantillon pris au hasard, de 50 commerces basé sur une connaissance corporative de ce monde spécifique, et un inventaire de toutes les variétes de plantes offertes à la vente dans ces échopes a été effectuée. Les participants, furent questionnés sur la rareté et la popularité des plantes à l’étalage, ainsi que sur l’origine et les fournisseurs de ces mêmes plantes. La méthode basée sur la raréfaction indiqua que la taille de l’échantillonage était adéquat. La diversité des échantillons fut déterminé en utilisant les indices écologiques, de diversité et se révéla, en comparaison, important. De plus, la corrélation linéaire de Spearman, le test x2, et les tests de probabilité éxacte de Fisher furent utilisés pout évaluer la probabilité de certaine taxa utilisée. Au moins 46% de la taxa vendue, montre une probabilité supérieure à la moyenne d’être utilisée, et la taxa tend a être récoltée parmi les familles de plantes situées dans la vicinité des lieux de vente. 511 espéces sont à la vente dans la région, et il n’y a pas de dominance particulière sur certaines especes. La présence de plusieurs groupes ethniques et la diversité végétale influence les habitudes commerciales qui constituent la base de l’étude.

Differential utilization and ethnobotany of trees in Kitulanghalo Forest Reserve and surrounding communal lands, eastern Tanzania.

This study documents the utilization aspects and distribution of ethnobotanical knowledge of the local people of Morogoro, Tanzania, as a first step towards sustainable utilization and conservation of tropical woodlands. A total of 133 arborescent species in 31 families was identified of which 69% had a variety of uses. These uses were classified into 12 categories and major uses were charcoal, firewood, medicine, and poles. Most tree species have occasional uses, but a few are exceptionally useful and thus their levels of utilization may far exceed their regeneration and production. The questionnaire survey indicated that 62% of the respondents agreed that traditional medical services were more available than modern services. Utilization surveys indicated that wooden poles are the building material used in 98% of the dwellings and storage structures, wild foods were useful for food security especially during drought years, and high quality timber trees have been depleted in the forest because of earlier exploitation by pit-sawing. The distribution of ethnobotanical knowledge indicated that much of the relevant ethnobotanical and utilization information was held by more aged members of the society and hence there is a clear need to capture this knowledge before it is lost. This study has shown that resources are defined by use and culture, and some components of ethnobotanical knowledge have potential for the sustainable management of miombo woodlands.RésuméL’étude porte sur les différentes utilisations, distributions ainsi que la connaissance ethnobotanique de l’ethnie locale du Morogoro en Tanzanie, comme première étape vers une meilleure utilisation et conservation des régions forestières tropicales. Un total de 133 espèces arborescentes ont été identifiée, 69% des 31 familles font l’objet de diverses utilisations. Ces utilisations sont classées en 12 catégories. Les principales utilisations sont le charbon, le bois de chauffe, la médecine. La majorité des espèces d’arbre sont utilisées occasionellement mais certaine sont très utiles et ainsi leur niveau d’utilisation dépasse de loin de taux de production et de régénération. Le questionnaire indique que 62% des personnes interrogées préfèrent la médecine traditionnelle plus accessible que celle moderne. Le bois est surtout utilisé comme matériaux de construction dont 98% pour maison et le stockage. La nourriture sauvage a été très utile pour l’hygiène alimentaire, spécialement durant les années de sécheresse et de forte exploitation forestière. La distribution de la connaissance ethnobotanique indique que la majorité des informations sont tenues par les personnes agées de la société et il est impératif de conserver cette connaissance avant qu’elle ne soit définitivement perdue. Cette étude a montré que les ressources sont définies par l’utilisation et la culture. Certaines parties de la connaissance ethnobotanique sont alors nécessaire pour une bonne exploitation des régions boisées du miombo.

Harvested and standing wood stocks in protected and communal miombo woodlands of eastern Tanzania

Miombo (Zambezian savanna) woodlands in protected and public (communal) lands of eastern Tanzania were examined to compare standing and harvested wood stocks and investigate different human disturbance gradients between the two utilization/management regimes. The standing volume in the forest reserve was 47±3.38(S.E.)m3ha−1 and the total removal volume (calculated from stumps) was 7.1±1.18m3ha−1. In the public lands, the standing volume was only 16.7±2.26m3ha−1 and the total removal volume was 19.62±2.58m3ha−1. Harvesting intensity decreased with increasing distance from village settlements and reserve boundaries but the pattern had no significant overall impact on standing stocks of wood. The Dar-es-Salaam–Morogoro highway, which bisects the study area is the major axis of disturbance. Multivariate analysis indicated that the linear combinations of physiographic variables significantly influence the pattern of tree harvesting. Commercial harvesting for charcoal overrides patterns from other harvesting purposes because of economic incentive and the wide range of species and size classes harvested. The estimated annual wood removal for all uses of 6.38±2.39m3ha−1 in public lands exceeds the reported mean annual increment (MAI) in the study area of 4.35 m3 ha−1 yr−1. Thus present patterns of harvesting are changing the structure and composition of the vegetation, especially in the communal areas and are not sustainable. This will increase pressure for harvesting in reserves.

Economics of charcoal production in miombo woodlands of eastern Tanzania: some hidden costs associated with commercialization of the resources

This paper assigns monetary values to commercial production of charcoal (using traditional earth kilns) in the miombo woodlands surrounding Kitulanghalo Forest Reserve in eastern Tanzania, through cost‐benefit analysis (CBA). Charcoal is the most commercialised resource in the study area and the net present value (NPV) for the charcoal business over a 15-year period was US

Direct-use values of woodland resources consumed and traded in a South African village

511 ha 1 . The profit from charcoal production is attributable to very low capital outlays, ‘free’ own labour, ‘free’ raw materials, lack of concern about associated external costs and high demand for charcoal. When the cost of labour, raw materials and opportunity costs were considered, the NPV value was negative (US

The impact of commercial harvesting on Warburgia salutaris (‘pepper-bark tree’) in Mpumalanga, South Africa

868 ha 1 ), indicating that profit realization is accomplished at the expense of other potential uses of the woodlands. The estimated local wood consumption for charcoal of 6.01 m 3 capita 1 year 1 is very high compared to subsistence firewood consumption of 1.5 m 3 capita 1 year 1 . The estimated area cleared for charcoal production locally was 1671 ha year 1 , which was about 13% of surrounding easily accessible communal woodlands in the area (B5 km from settlements and B 10 km from the Dar-es-Salaam‐Morogoro highway), which were estimated to cover 13 350 ha. This shows that although commercialisation of wood resources provides tangible monetary benefits to rural communities, it also contributes to the resource depletion that will ultimately threaten their long-term survival. We recommend some policy interventions in order to safeguard the resources.

Market profiles and trade in medicinal plants in the Lowveld, South Africa

SUMMARY This paper examines the contribution of secondary resources harvested from a savanna ecosystem to household income in Thorndale village, South Africa. The valuation of these resources provides a key tool for adopting sustainable development practices. The study shows the relevance of the dependence of rural people on secondary resources and implications for social and economic equity. Fuelwood, edible herbs and thatch grass contributed 80.6% (

Topo-edaphic, floristic and physiognomic gradients of woody plants in a semi-arid African savanna woodland

492.53) of the total gross direct-use value (