Dry Forest Areas Research Articles

Coppice regrowth in a disturbed tropical dry limestone forest in Jamaica

The Hellshire Hills are an extensive area of tropical dry forest over limestone, located on the south coast of Jamaica. Despite being a protected area, they are subject to encroachment and clearance by charcoal burners, leaving a relatively pristine core within more disturbed areas of forest. Future management requires a consideration of the forest’s resilience to such disturbance, and this study reports on coppice regrowth following clearance. The number of coppice shoots and the length and diameter at breast height (DBH) of the leading shoots were measured on tree stumps 14 months after they were cut in an experiment. Coppice regrowth after cutting was measured on a total of 476 stumps, representing 51 species. Coppice production and growth was vigorous as there was an extremely high incidence of coppice regrowth among and within the species in this forest after it had been cut. Initial regrowth was high with the diameter recovered by the leading shoots after 14 months approximating to 29% per year. Of the 51 species sampled three did not coppice at all and the average percent of individuals found with shoots within each species was 81%. The height and diameter of the leading shoots was significantly different among the species and the average height recorded of the leading shoots was 114 cm while the average diameter recorded was 10 mm. Larger sized stems (>10 cm DBH) on average produced more coppice shoots and larger sized shoots than smaller sized stems (<10 cm DBH) while smaller sized stems recovered more biomass than larger sized stems irrespective of species. The average diameter of the leading shoots decreased significantly with increasing shoot densities. At the species level there was a significant relationship between stem diameter and the number of shoots produced in seven of the 27 species analysed and three species returned significant relationships between stem diameter and average height of leading shoots. Coppice regrowth clearly offers considerable resilience to disturbance in this dry forest where successful regeneration by seed is highly susceptible to rainfall seasonality. However, the different abilities of species to produce coppice shoots will likely affect long-term species diversity if the present rate of clearance continues.

Nesting Sites of the Carpenter Ant,Camponotus vicinus(Mayr) (Hymenoptera: Formicidae) in Northern Idaho

Camponotus vicinus (Mayr) is a common ant species found in the PaciÞc Northwest. It is an important predator of many forest insect pests, a potential biological control agent, and is also a serious structural pest. However, little knowledge is currently available about its nest location and distribution. The study is designed to examine the biotic and abiotic factors in affecting the distribution of carpenter ants. Investigations during 1993 and 1994 showed that in conifer forests in northern Idaho, C. vicinus was found nesting mostly in fallen logs and tree stumps. The diameter of logs used as nest sites was 5Ð55 cm, but most nests were found in logs with diameters between 15 and 35 cm. Tree bark, duff, and wood beneath stones were also used as nest sites. Most nests were found in dry areas associated with an opening in the forest canopy. This kind of site can be called a C. vicinus carpenter ant zone. To study the effect of biotic and abiotic factors on nest aggregations of C. vicinus, Þve factors were tested in conifer forests of northern Idaho: habitat availability, food abundance, competition, moisture, and temperature. Competition is not a main factor in restricting the distribution of C. vicinus because food and habitat are relatively abundant throughout the forests. The main factors that restrict the distribution of the carpenter ant, causing colonies to aggregate in open and dry forest areas are an interaction between temperature and moisture during the daylight hours.

Late‐glacial and Holocene history of the dry forest area in the south Colombian Cauca Valley

AbstractTwo sedimentary cores with pollen, charcoal and radiocarbon data are presented. These records document the Late‐glacial and Holocene dry forest vegetation, fire and environmental history of the southern Cauca Valley in Colombia (1020 m). Core Quilichao‐1 (640 cm; 3° 6′N, 76° 31′W) represents the periods of 13 150–7720 14C yr BP and, following a hiatus, from 2880 14C yr BP to modern. Core La Teta‐2 (250 cm; 3° 5′N, 76° 32′W) provides a continuous record from 8700 14C yr BP to modern.Around 13 150 14C yr BP core Quilichao‐1 shows an active Late‐glacial drainage system and presence of dry forest. From 11 465 to 10 520 14C yr BP dry forest consists mainly of Crotalaria, Moraceae/Urticaceae, Melastomataceae/Combretaceae, Piper and low stature trees, such as Acalypha, Alchornea, Cecropia and Celtis. At higher elevation Andean forest comprising Alnus, Hedyosmum, Quercus and Myrica was common. After 10 520 14C yr BP the floral composition of dry forest changed, with extensive open grass vegetation indicative of dry climatic conditions. This event may coincide with the change to cool and dry conditions in the second part of the El Abra stadial, an equivalent to the Younger Dryas. From 8850 14C yr BP the record from La Teta indicates dry climatic conditions relative to the present, these prevailing up to 2880 14C yr BP at Quilichao and to 2720 14C yr BP at La Teta. Severe dryness reached maxima at 7500 14C yr BP and 4300 14C yr BP, when dry forest reached maximum expansion. Dry forest was gradually replaced by grassy vegetation, reaching maximum expansion around 2300 14C yr BP. After 2300 14C yr BP grassy vegetation remains abundant. Presence of crop taxa (a.o. Zea mays), disturbance indicators (Cecropia) and an increase in charcoal point to the presence of pre‐Columbian people since 2300 14C yr BP. After 950 14C yr BP, expansion of secondary forest taxa may indicate depopulation and abandonment of previously cultivated land. After 400 14C yr BP, possibly related to the Spanish conquest, secondary forest expanded and charcoal concentrations increased, possibly indicating further reduction of cultivated land. During the past century, Heliotropium and Didymopanax became abundant in an increasingly degraded landscape. Copyright © 2002 John Wiley &amp; Sons, Ltd.

Land cover change in two protected areas of Guinea-Bissau (1956-1998)

The objective of this work was to quantify and spatially characterize land cover change in the regions of the Cacheu and Orango protected areas (Guinea-Bissau). Land cover maps from 1956 and 1998 were co-registered and rasterized to the same spatial resolution in a geographic information system (GIS) and the land cover classes of both maps aggregated to a new common legend. Classification of Landsat Thematic Mapper images and field checking were used to generate the 1998 map. Comparisons between the two dates indicate that major changes have occurred in the Cacheu area, both in the extent and the spatial distribution of some vegetation classes, with decreases in areas of mangrove, dry forest and palm grove, and large increases in mudflats and savanna. In Orango, changes are less extensive, but the onset of some of the trends verified in Cacheu can be identified. The results are interpreted, taking into account land use practices in the two study regions, and will hopefully become a management and conservation tool for the local park authorities.

Egg-Laying Activities and Reproductive Traits in Females of Oplurus cuvieri cuvieri

Egg-Laying Activities and Reproductive Traits in Females of Oplurus cuvieri cuvieri

NO x emissions from biomass burning of shifting cultivation areas from tropical deciduous forests of India – estimates from ground-based measurements

Biomass burning in the tropics is an important source of trace gases. Shifting cultivation in India is one of the major sources of biomass burning activities, during which due to combustion, several trace gases are emitted into the atmosphere. NO x emissions are relatively important as they affect the tropospheric photochemistry. In the present study, an attempt has been made to quantify the NO x emissions from shifting cultivation areas of tropical dry deciduous forests of India, at two sites. Fuel load, fuel characteristics, and nutrients with respect to carbon and nitrogen have been analyzed. Emission ratios have been calculated relative to CO 2. Results of the study suggested that fuel load ranged from 12–15.3 t ha −1. Fire intensity at the first site was 3207 kcal s −1 m −1 and 2882 kcal s −1 m −1 at the second site. The differences in the fuel moisture were found to be less than 10% at both of the sites. The CO/CO 2 ratio at the two sites did not vary much due to the low variation in moisture content. The carbon and nitrogen loads for the two sites ranged from 5603 t C ha −1 to 286 t N ha −1 and 6364 t C ha −1 and 239 N ha −1, respectively. Using the relation of estimating the emission factor (EF) for estimating the NO x emissions (EF (NO x )=−1.5+3.9 nf, where, (r=0.95) EF(NO x ) is the emission factor for NO x in grams of nitrogen per kilogram of dry matter (g N kg −1 dm) burned and `nf’ is the percent of nitrogen bound within the plant matter, for tropical deciduous forests, suggests an emission rate of 7.0 (g N kg −1 dm) for the first site, and 4.7 (g N kg −1 dm) for the second site when compared to actual measured emission rates of 4.8 (g N kg −1 dm) for the first site and 3.5 (g N kg −1 dm) for the second site, indicating a higher estimate for the global regression relation used by Dignon and Penner. The emission factors computed from nitrogen content of the fuel material for tropical dry deciduous forests are nearer to the relation obtained for African Savanna fires. Comparison of the measured emission factors for the tropical deciduous forests with other ecosystems has been made in the paper.

Effects of Canopy Gaps, Topography, and Soils on the Distribution of Woody Species in a Central Brazilian Deciduous Dry Forest1

ABSTRACTThe interrelationships between the distribution of woody species and environmental variables were investigated in an area of deciduous dry forest in Santa Vitöria, central Brazil. This is the first study of a vanishing type of dry forest which grows on base‐rich soils originating from the basalt bedrocks of southern Goiás and western Minas Gerais. A survey of topography, soil properties, canopy gaps and woody plants (≥5 cm diameter at the base of the stem) was conducted in 50–15 × 15 m quadrats. The soils were classified into the following soil series: Hapludolls → Haplustolls → Haplustolls → Ustropepts → Rhodustalfs. This series corresponded to a gradient of increasing elevation and effective soil depth and decreasing slope gradient, soil organic matter and total exchangeable bases. A canonical correspondence analysis and a detrended correspondence analysis indicated that plant species’abundance distribution was significantly correlated with both the relative area of canopy gaps in the quadrats and the soil‐topography gradient. Presumably, the critical factors involved in these two gradients are, respectively, light and ground water regimes. The influence of canopy gaps (i.e., light) was surprising and has not been documented previously for tropical deciduous dry forests.

Changes in small mammal assemblage structure across a rain forest/open forest ecotone

The effect of the change in vegetation structure from closed rain forest to tall open forest on the small mammal assemblage was studied by live trapping at three sites where the ecotone was very narrow (&gt; 20 m) near the southern end of the Wet Tropics World Heritage Area of Australia. Habitat heterogeneity was significantly higher in the mixed open forest/ecotone area than in the adjacent rain forest. There was a large change in the struture of the small mammal assemblage coincident with the vegetation discontinuity. Although the species richness of small mammals was relatively constant across the gradient, the evenness and diversity of the assemblage declined across the transition from open forest into rain forest and biomass increased, largely due to the high abundance of Rattus fuscipes in the rain forest. The results suggest that the species richness of the small mammal assemblage was not determined by the spatial heterogeneity of the vegetation struture. The species composition of the rain forest is probably related to the historical biogeography of the area whereas the species richness of the wet sclerophyll forest is probably due to a mass-area effect from the adjcant large areas of rain forest and dry sclerophyll forest. However, the evenness, and therefore the diversity of the assemblage, was strongly affected by habitat heterogeneity.

The impact of clearing and conversion of dry Afromontane forests into arable land on the composition and density of soil seed banks

The soil seed bank was sampled in forest, recent gaps and arable land at a site within the dry Afromontane forest belt in eastern Ethiopia. The regeneration in the gaps was also followed for three years. At least 132 species of flowering plants were identified in the 0–3 cm soil layer with total densities ranging between 9400 and 20740 seeds/m 2. The highest number of species was recorded from the forest while the highest seed density was found in the arable land. Herbs were represented by the largest numbers of species and seeds in the seed bank in all three sampling areas. In all cases, the seed bank was dominated by a few species, reflecting differences in seed longevity and movement of seeds in the soil. Contribution of woody species to the soil seed bank was 15% in the forest while it was less than 1% in gaps and arable land. Seed density and number of species decreased with increasing depth, although species differed in the depth distribution of their seeds. The gaps were colonized by dense vegetation within three years by herbaceous species originating from the soil seed bank and newly dispersed seeds as well as by woody species sprouting from stumps and/or from pre-existing seedlings. However, if clearing of forests is followed by permanent cultivation which is typically the case, almost all of the woody and a part of the herbaceous components of the forest soil seed bank diminish through time and are largely replaced by a new set of herbaceous species. Regeneration of woody species by sprouting is also prevented by the complete removal of stumps from the arable land. This implies that natural regeneration of dry Afromontane forest areas converted into permanent arable land will be very difficult if the adjcent patches of forests are completely removed.

Distribution and abundance of fungal sporocarps and diggings of the Tasmanian bettong, Bettongia gaimardi

Abstract The distribution and abundance of diggings of the Tasmanian bettong Bettongia gaimardi and sporocarps of hypogean fungi (the major dietary item of bettongs) were studied in an area of dry sclerophyll forest in northern Tasmania. Digging activity was greatest during August. Sporocarp production was expected to be greatest at this time due to high soil moisture levels. The distribution of both hypogean sporocarps and the diggings of bettongs was highly clumped. Degree of clumping of diggings varied seasonally being greatest in summer and lowest in winter. Digging activity was greatest in sandy soils and least in dolerite soils. This was thought to result from the lower fertility sandy soils having greater densities of sporocarps. Lateritic soils, although the most infertile, had fewer diggings than sandy soils. This is probably due to the difficulty of digging in these gravelly, often cemented soils. The depth of diggings was greatest in winter when soil moisture was high. Mesophellia was the most frequently occurring sporocarp and spores of this genus were the most abundant in the faecal pellets of bettongs.

Regeneration of tropical dry forests in Central America, with examples from Nicaragua

. This paper focuses on the management potential of natural forests in the tropical dry zones of Central America, particularly Nicaragua. Distribution and status of dry forest formations are reviewed. Two case studies from the Pacific coast of Nicaragua are presented to illustrate the disturbance created by traditional utilization, and to show the relatively high potential for natural forest management, with many of the tree species having economic value. Natural forest management, together with conservation and reforestation, is viewed as the main management option for the tropical dry forest areas. In spite of its importance, this option has received little attention or promotion from the governmental forestry sector. Four complementary options which can be devised for silvicultural work in production forests are: encouragement of advanced growth of desirable tree species, inducement of natural regeneration, coppice management, and compensatory planting. These options form different strategies for rehabilitation of the production and conservation functions of the forest and may well be combined in the same area. Research applied to better utilization of the forest resources should form an intrinsic part of rural development programs. Research work in tropical dry forest areas should focus on ecological, as well as socio-cultural and economical aspects related to the management options. Experimental sites are important enabling and securing long-term basic and applied biological research. They may also serve as units for demonstration, training and extension.

The ecology of Hypogeomys antimena, an endemic Madagascan rodent

The subfamily Nesomyinae comprises 11 species of rodents endemic to the island of Madagascar. They show considerable ecological and anatomical diversity but little is known of their biology and they have not been studied to any extent in the wild. We present here the results of a nine‐week field study of Hypogeomys antimena, the largest of the Nesomyinae, found only in a restricted area of dry deciduous forest in western Madagascar. Radiotracking data gave a mean home range estimate of 3.5+0.71 ha for 10 animals (five males, five females). Individuals from the same burrow had highly overlapping ranges but ranges of animals from neighbouring burrows showed minimal overlap. We suggest that H. antimena lives in social units, probably consisting of a pair plus their offspring, which occupy exclusive territories. A mark/recapture study gave a minimum population estimate of 48 animals/km2 in the study site. The conservation of the species is discussed with reference to its limited distribution and current habitat degradation in the area.

The carnivore community in a dry tropical forest mosaic in Huai Kha Khaeng Wildlife Sanctuary, Thailand

ABSTRACTAn assessment of carnivore species richness and food habits was carried out in a 100 km2 area of dry tropical forest in Huai Kha Khaeng Wildlife Sanctuary, Thailand. Twenty-one carnivore species of five families were found to be feeding on at least 34 mammal species, as well as birds, lizards, snakes, crabs, fish, insects, and fruits. Forty-four percent of the prey identified in faeces of larger carnivores, primarily leopards, consisted of barking deer, Muntiacus muntjak. Sambar deer, macaques, wild boar, porcupine, and hog badger were important secondary prey items. In faeces from small carnivores (&lt; 10kg), murid rodents accounted for 33% of identified food items. The two most frequently encountered mammalian prey species were the yellow rajah rat, Maxomys surifer, and the bay bamboo rat, Cannomys badius. Non-mammal prey accounted for 21.3%, and fruit seeds for 12.4%, of all food items found in small carnivore faeces.

Bothrops ophryomegas Bocourt (Serpentes: Viperidae) in Costa Rica: distribution, lepidosis, sexual variation and karyotype

The distribution, karyotype and morphological characteristics of Bothrops ophryomegas from Costa Rica are described. This species presents a conspicuous sexual dimorphism and dichromatism. It is distributed in the dry forest areas of Guanacaste and Puntarenas. Its karyotype is indistinguisable from those described for other crotaline species.

The impact of grazing pressure in clearfelled, burned and undisturbed eucalypt forest

An area of dry eucalypt forest on dolerite in southeastern Tasmania with comparable sites that were a) unlogged, b) clearfelled, c) clearfelled and slash-burned, was monitored over a 24 month period. Detailed records were made of plant species composition and cover on floristically similar fenced and unfenced permanent plots in two major vegetation types. Mammal faecal pellets were cleared from each of the unfenced plots and subsequently counted and attributed to species of origin. For the six combinations of treatment and vegetation type pellet deposition rate was highly correlated with differences in the rate of change of species cover between fenced and unfenced plots and the lifeform composition of the vegetation. The greatest changes were observed in the clearfelled, burned area, while there was relatively little change in the undisturbed forest. Grass and herb species were generally disadvantaged by mammal exclusion while shrubs and graminoids generally grew faster in the fenced plots.

Birds in a partly clearfelled dry eucalypt forest on dolerite in southeastern Tasmania

An area of dry eucalypt forest on dolerite in southeastern Tasmania was clearfelled in 1981. A portion of this area was subsequently slash-burnt and aerially sown in 1982, whilst the rest of the area was left unburnt and unsown. A monthly bird census was conducted during 1983-1984 in surrounding uncut, mature forest and also on the clearfelled area. Species were recorded together with the habitat in which they occurred and the particular plant species being utilised. A total of 46 avian species were recorded during the monthly censuses, with most species and individuals being observed in the spring months. The numbers of species and individuals recorded on the burnt and unburnt clearfelled areas were low in comparison with those observed in the uncut forest. In general, those species able to utilise open-ground habitats tended to be the least affected by dearfelling followed by slash-burning. However, the unburnt clearfelled area provided foraging sites for certain species, in preference to the nearby slash-burnt area. Many individuaH~'recordedin the clearfelled areas made use of trees left standing after logging. The use of fire in dry forest management practice and the importance of cull trees are discussed.

Micetomas de Localizacion Podal de Etiologia Doble

A patient coming from an area of dry tropical forest was studied. This patient had in his right foot two tumor-like growths localized, one in the anterior and superior part of the foot, the other near the malleoli. From the first tumor, light-colored grains were obtained, and Actinomadura madurae was cultured. From the tumor near the malleoli only black grains were isolated from which a Pyrenochaeta sp. was cultured.

Characteristic temperature spectra in a tropical dry evergreen forest area

Temperature spectra for time series spanning 23 days in June–July 1970 were computed at different levels of two 50 m high instrumented towers. One tower was located in a 450 m diameter clearing and the other in a forest, 500 m away. The spectra for both cases exhibit significant diurnal and semidiurnal peaks. An attempt is made to explain the semidiurnal peak in terms of the topographical features of the surrounding environment.

Phytophthora cinnamomi in the Brisbane Ranges: Patterns of Disease Extension

Three patterns of disease extension were observed in areas of uncultivated shrubby dry sclerophyll forest invaded by the pathogen Phytophthora cinnamomi. Environmental factors were found to determine which pattern developed. Where inoculum was spread downhill with drainage water, diseased areas were separated by clearly defined boundaries from unaffected vegetation. Where disease extension occurred uphill through soil or from root to root, a wavy boundary marked the active disease front. Investigations showed that absence of disease extension for 4 years in highly susceptible vegetation may be associated with differences in soil characteristics.

Annually recurrent epidemic polyarthritis and Ross River virus activity in a coastal area of New South Wales. II. Mosquitoes, viruses, and wildlife.

During field investigations of recurrent small outbreaks of epidemic polyarthritis on Port Stephens Peninsula, New South Wales, 12 strains of Ross River virus (RRV) were recovered from pools of mosquitoes collected in a small area of dry sclerophyll forest on stable sand dunes in the vicinity of the township of Nelson Bay. The viruses were recovered during April of 3 successive years. The Nelson Bay strains of RRV are antigenically indistinguishable from Queensland strains by routine serological methods, but consistent biological differences are apparent in laboratory mice. It is unlikely that the virus is annually reintroduced from northern foci. Pseudomys novaehollalldiae, the New Holland mouse, is the only vertebrate so far found in the area which fulfills the criteria for a reservoir vertebrate host, but it is not suggested that this is the only host involved. Most RRV strains were recovered from Aedes vigilax, but the highest infection rates were obtained in pools of Culex and Mansonia species. One recovery was made from Mansonia linealis, which has not previously been recorded as a vector of this virus. In addition to RRV, 9 strains of Edge Hill virus, 4 strains of a previously undescribed Mapputta group virus, 1 orbivirus related to Eubenangee, and 1 uncharacterized probable arbovirus were recovered from mosquitoes collected in the same area.