Showing papers on "Undergrowth published in 2001"

An interactive effect of simultaneous death of dwarf bamboo, canopy gap, and predatory rodents on beech regeneration

Abstract: To clarify the interactive effect of the simultaneous death of dwarf bamboo (Sasa kurilensis), forest canopy gap formation, and seed predators on beech (Fagus crenata) regeneration, we analyzed beech demography from seed fall until the end of the first growing season of seedlings in an old-growth forest near Lake Towada, northern Japan. The simultaneous death of S. kurilensis took place in 1995. We established four types of sampling site differing in forest canopy conditions (closed or gap) and Sasa status (dead or alive). Beech seed survival and emergence ratio were both highest in gaps with dead Sasa (gap-dead), because rate of predation was lowest. Seedling survival during the first growing season was also highest in the gap-dead treatment, because of less predation and less damping off. As a result, even though density of seed fall was lowest in the gap-dead treatment, the living seedling density there was highest at the end of the first growing season. Predation, which caused the greatest mortality during the seed and seedling stages, was significantly lower at both sites in gaps and sites with dead Sasa. This was probably due to changes in the behavior of rodents in response to the structure of the forest canopy and undergrowth. Both the death of Sasa and canopy gap formation allowed seedlings to avoid damping off because of the high light availability. The indirect effect of the simultaneous death of Sasa and canopy gap formation in reducing predation contributed more to beech regeneration than their direct effect in increasing light for the seedlings.

Effect of exotic tree plantations on plant diversity and biological soil fertility in the Congo savanna: with special reference to eucalypts

Abstract: In the southern coastal region of Congo near Pointe-Noire, savanna covers large areas on very poor sandy soils. These savannas have been used since 1978 for plantations of fast growing trees, mainly eucalypts, which are grown commercially. A particular feature of the Congolese plantations was their establishment on savanna with poor soil and vegetation. This document reports a study on the importance of the biological factors in fertility. The report is divided in three parts: (i) The effect of both savanna and forest on undergrowth colonisation, and the trends of understorey vegetation changes with age. (ii) The relationships between vegetation and fertility are closely linked to litter and soil organic matter quality and quantity these were studied in an age series of eucalypt hybrids and clones. (iii) The density of the main taxa of macrofauna and nematodes was assessed according to the age of plantation and logging. Nitrogen fixation ability related to the dramatic N shortage expected to occur in aging plantations was also studied. In the harsh environment like the Congolese savanna, silviculture is a land use that has numerous positive effects although there are many problems still to be addresed. The increase in soil organic matter accounts for many positive changes is a fragile process. All management practices likely to decrease inputs, such as the burning of harvest residues, the harvest of twigs and leaves for fuel, and the harvest of logs with the bark, are expected to counteract environmental improvements resulting from eucalyptus growth. The choice of species and hybrids beside their growth and wood qualities should take into account litter quality and decomposition rate. Further research is needed on the cumulative effect of silvicultural practices involved in short-rotation forestry and its relation with soil organic matter. (YS)

Difference in microhabitat-related regeneration patterns between two subalpine conifers, Tsuga diversifolia and Abies mariesii, on Mount Hayachine, northern Honshu, Japan

Abstract: Seedling and tree-establishment microhabitats of Tsuga diversifolia and Abies mariesii were examined on the herb- and dwarf bamboo-dominated forest floor on Mount Hayachine, a mountain under intermediate snow conditions in northern Honshu, Japan. The four microsite types were fallen logs, buttresses, rocks and ground. The ground substratum was further divided into four subtypes by dominant undergrowth species: Lycopodium, Pteridophyllum, Carex and dwarf bamboo. The establishment of T. diversifolia seedlings on the ground was scarce, and depended mostly on non-ground microsites (i.e. fallen logs, buttresses and rocks). The seedling establishment of A. mariesii was not dependent on specific substrata, although on the ground, establishment sites were limited to the Lycopodium subtype situated on convex sites. Among the microhabitats for seedling establishment, larger trees of A. mariesii rarely occurred on higher portions of the non-ground microsites. In contrast, T. diversifolia could grow up to the height of canopy-layer trees in such microsites. Thus, non-ground microsites seem to be unsuitable for tree establishment in A. mariesii, and are probably useful microhabitats for regenerating T. diversifolia to avoid competition with A. mariesii. We also compared seedling-establishment microhabitats for the two conifers between Mount Hayachine and two other mountain regions under different undergrowth conditions (moss-dominated and dense dwarf bamboo-dominated). Our findings suggested that seedling recruitment in non-ground microsites was primarily determined by undergrowth conditions; T. diversifolia preferred such microsites where the moss-covered area was low, and A. mariesii preferred where dwarf bamboo-covered area was high.

Succession and regeneration patterns of East African mountain forests A review

Abstract: Regeneration and succession processes in montane forests of Kenya and parts of Ethiopia were investigated. The slowly growing camphor tree, Ocotea usambarensis, regenerates mainly by suckers from old root systems. Undamaged seeds were very rarely seen, and, apparently are viable only for a few days. After natural breakdown of an old tree, the gap is filled by fast growing species, mainly Macaranga kilimandscharica and Neoboutonia macrocalyx, in the shade of which the young Ocotea suckers can establish. After the death of the secondary species, whose germination requires full sunlight and is inhibited in the shade, the Ocotea forest recovers. Large scale logging of Camphor trees predominantly destroys the regeneration of Ocotea and leads to secondary forest types, which regenerate in own cycles. The high number of big game was found to be without impact on the natural regeneration of Ocotea. The Cassipourea malosana dominated forest regenerates as a mosaic-climax without a single species becoming dominant. Cedar forests dominated by Juniperus procera regenerate most efficiently after fire. Without recurrent burning, the forests of the lower and middle part of the montane zone, regenerate to climax associations dominated by broad-leaved trees as Olea capensis ssp. hochstetteri, Olea europaea ssp. cuspidata and Podocarpus latifolius. On higher altitudes Juniperus procera always remains dominant even if fire does not occur for a longer time period. The high population density especially of buffaloes seems to inhibit successful regeneration in many parts of the Juniperion, due to intensive browsing and in particular trampling. The African Bamboo, Sinarun- dinaria alpina, shows a distinct growth cycle and can grow for extremely long periods in the vegetative state before flowering, especially so at the borders of its area. After flowering and dying of the bamboo, in most areas a dense Sambucus africana shrub is formed into which bamboo is invading from old rhizomes again. In Ethiopia, regeneration occurs directly, without an interspersed Sambucus stage. The uniform age of the Hagenia stands suggests that regeneration in these forests occurs suddenly after a disturbing event. Germination tests yielded, that Hagenia seeds are not germinating unless the competing undergrowth is removed. As fire is the only natural factor able to clear the grass layer of larger areas, it is assumed, that the reproduction of the subalpine forests depends on occasional burning.

Morphology and growth of deciduous and evergreen broad‐leaved saplings under different light conditions in a Chinese beech forest with dense bamboo undergrowth

Abstract: This study compared the morphological and growth adjustment of saplings from three shade- tolerant canopy species (Castanopsis lamontii, Lithocarpus hancei and Fagus lucida; Fagaceae) under different light conditions in a Chinese beech forest with dense bamboo undergrowth. Only F. lucida is deciduous, and it had the most flexible morphology. In shade, F. lucida had flat or bent topshoots and horizontal branches to maximize light interception, while in conditions of high light intensity, it formed vertical topshoots to promote growth in terms of height, and upright branches to mitigate excessive sun exposure on the leaves. In contrast to F. lucida (beech), the evergreen species always had vertical topshoots regardless of light conditions. In shady conditions, the evergreens had greater annual growth rates in terms of both height and diameter than the beech, and between the evergreens, the species bearing plagiotropic branches grew faster in diameter than the species bearing orthotropic branches. The evergreen trees had thicker leaves and thicker stems compared to the beech. It was concluded that the evergreen saplings have advantages over beech saplings in terms of current growth in the forest understorey; whereas, morphological and growth flexibility in the beech aids in its persistence in the understorey.

Habitat-structural and meteorological parameters influencing the activity and local distribution of the golden-striped salamander, chioglossa lusitanica

Abstract: , in a forest plot in northwestern Portugal. A large proportionof the local population inhabited an underground watercourse and foraged in the woodland, leavingand entering the underground shelter through three holes. Surface activity – measured as thenumber of salamanders out in the open and their distance from the inferred shelter – was positivelyassociated with relative humidity and precipitation. A negative relationship between dispersiondistance and temperature was found in females. Distances moved were higher for adult salamandersthan for juveniles. Spatial models indicated that males, females and juveniles differed in habitatutilization. The frequency of occurrence of salamanders at the surface was highest in the area ofthe stream (adults and juveniles, near dry-stone walls (males and juveniles), in areas with a higherthan average density of trees (adults) and in areas of dense undergrowth (females ). The resultssuggested that (1) the underground watercourse served as a retreat from which the salamanderswould visit the surface, (2) dry stone walls functioned as retreats rather than as foraging grounds,and (3) trees and dense vegetation served as shelter for foraging salamanders. The results arecompared with those for phylogenetically related and morphologically similar species.

Rehabilitation of tropical rainforests based on indigenous species for degraded areas in Sarawak, Malaysia

Abstract: A study was conducted on forest rehabilitation based on indigenous species at the Universiti Putra Malaysia, Bintulu, Sarawak. Areas of open abandoned shifting cultivation, man-made mounds, Macaranga secondary forest and shrubby undergrowth were used for trial planting with different types of planting techniques. The research showed that selected species from the natural vegetation community easily adapt to the site conditions similar to their native habitat. The planted seedlings were classified as light demanding, shade tolerant and late growth species on the basis of their height growth performance in the trials. The indigenous tree species recommended for checkerboard plantations are: Shorea ovata, S. mecistopteryx, S. macrophylla, Dryobalanops aromatica, Parashorea parvifolia, Hopea beccariana, Durio carinatus and Eusideroxylon zwageri.

Paleoenvironmental study of the Carquefou site (Massif Armoricain, France) from the end of the Sub-boreal

Abstract: The town of Carquefou, some 10 km northeast of Nantes on the left bank of the river Erdre, occupies a site long associated with human activity. During road construction east of the town, ditches, enclosures and post holes characteristic of the late la Tene were discovered at the locality of “Le Clouet”, which led us to obtain core samples from a nearby peat bog. These investigations indicated the changes in vegetation since 3915±95 uncal B.P., [2828 (2459) 2074 cal B.C.]. The slopes in the surroundings of the bog have been relatively treeless since the Bronze Age, but a very open woodland vegetation composed of Tilia, Corylus and Quercus has been maintained until the present day. In the area around the bog, and Alnus wood with an undergrowth of Cyperaceae was the dominant vegetation, despite some changes probably related to human occupation since the Bronze Age. Beginning at 955±35 uncal B.P. [1004 (1036, 1144, 1146) 1181 cal A.D.], in the Middle Ages, the alders disappeared almost totally, apparently because of clearance or an increase in water level. Human presence led to intensified cultivation of different crops including Cannabis and especially Cerealia. Finally, the presence of a variety of anthropogenic indicator plants (Cichorioideae, Asteraceae, Plantago lanceolata, etc.) suggests that cattle were reared in the vicinity of the site.

Dynamical characteristics of undergrowth plant diversity in chinese fir plantations

Abstract: The dynamic characterristics of succession process of undergrowth plants in different aged Chinese fir plantations were studied.The results showed that in accompanying stage of accidental species,undergrowth plant species and quantities flourished first,and the structure was very simple. In sparse stage of undergrowth plants, species and quantities were few,and structure was simple. In relatively stable stage of undergrowth plants,species and quantities increased, and Chinese fir community formed stable 3-layer structure including Chinese fir layer,shrub layer and herb layer. In invading succession stage of undergrowth plants, species composition and quantities flourshed again,some broad-leaved tree species started to grow into tree layer,and the multi-species and multi-layer community structure was formed. The α diversity indexes of undergrowth plants were obviously different and fluctuated. The richness index, diversity index and evenness index of total undergrowth plants of shrub layer were higher in young Chinese fir plantation. In the stage of closed forest stand, all indexes obviously decreased, then increased again, reaching maximal value in old-growth plantation. Vertical structure of species diversity showed shrub layerherb layerliana plant in 3,9 and 31 year-old plantations, in 20 year-old plantation, herb layershrub layerliana plant, and in old-growth Chinese fir plantation, shrub layertree layerliana plantherb layer. Tab 3, Ref 6

Occurrence and activity budget of the leopard tortoise, Geochelone pardalis, in northern Tanzania

Abstract: Occurrence and activity budget of the leopard tortoise, Geochelone pardalis were studied in northern Tanzania between October 1993 and June 1996. Tortoises occurred most frequently in short grass (51.5%) and along roads and track verges (33.9%), but only occasionally in the bush undergrowth (6.7%) and shambas (3.6%). Walking (46.3%) and feeding (37.2%) were the most frequent activities. Resting was observed only occasionally (13.6%) while courtship (1.9%) and drinking (0.9%) were rarely recorded. Activity budget differed significantly between the age classes and habitats, but not between the sexes. Juveniles walked more frequently (59.3%) than other age classes. Walking was most frequent along roads and tracks (68.8%). Adult tortoises rested more frequently (18.7%) than other age classes but the difference was not significant. The proportions of individuals resting in the various habitats differed significantly, with resting being most frequent in the shrub undergrowth (93.3%). Juveniles were observed feeding less frequently than other age classes but the difference was not significant. Feeding was recorded in all habitats, but it was least frequent in the shrub undergrowth. Tanzania Journal of Science Volume 27 (2001), pp. 87-99

Ecophysiological Responses of Larix sibiricaLedeb. and Pinus sibiricaDu Tour Undergrowth to Climate Change

Abstract: The effects of probable climate change—an increase in atmospheric CO2(by two times), air temperature, precipitation—on CO2exchange and temperature dependence of net photosynthesis in the larch and Siberian stone pine undergrowth formed in the light larch forests of West Siberia were studied in chambers with an artificial climate. The change of the aforementioned ecological factors caused an increase in the temperature optima of photosynthesis and the range of optimum temperatures (in the case of Siberian stone pine, to a slightly greater degree). Therefore, the ranges of both species may broaden, and the Siberian stone pine can expand to the north, displacing larch tree stands.

A Long-term Study on Development and Succession of Undergrowth Vegetations in Chinese Fir (Cunninghamia lanceolata) Plantations with Different Density

Abstract: In 1986,a study was initiated on the 8 or 9 year old Cunninghamia lanceolata plantations with different retained density after thinning at the Shangcun Forest Farm of the Experimental Center for Subtropical Forestry under the Chinese Academy of Forestry (CAF), which is located in Fenyi County of Jiangxi Province. Six sample plots were set up in the Chinese fir plantations with stand density of 3 000 trees·hm -2 , 2 400 trees·hm -2 and 1 500 trees·hm -2 and with the canopy density of 0 9,0 7 and 0 6 respectively. The annual investigation has been made for 13 years on the development of undergrowth vegetation in the sample plots. The results showed that the undergrowth vegetation developed rapidly and flourished in the plantations with canopy density ≤0 7 the coverage of undergrowth vegetation had reached 80%～90%,with the total amount of undergrowth biomass of 4 or 5 t·hm -2 and three storey stand structure was formed in these plantations 8 to 10 years after thinning. But,in the plantations with high density,the undergrowth vegetation started developing only when the plantation grew up to 20 years old. Therefore,reasonable thinning of the plantation can be an effective way for well development of undergrowth vegetation Generally,when the plantation with initial planting density of 2 500～3 000 trees·hm -2 grows up to 10 years old,the reasonable retained stand density should be 1 500～2 000 trees·hm -2 and the canopy density should be 0 6～0 7 after thinning. The results also showed that the main undergrowth plant species are fernery in Cunninghamia lanceolata plantations

Studies on β-diversity index of undergrowth plant in Chinese fir plantation

Abstract: Undergrowth of plants in a Chinese fir plantation in different growth stages and site indices has been quantitatively analysed by using β diversity index formulas. The results showed that the values of β diversity index of undergrowth plant in different growth stages and site indices are obviously different, in which the difference between 56 year old and 3 year old forests is greatest, and the closer to 56 year old in growth stages, the smaller in β diversity index values, in each Chinese fir community, the difference of β diversity index values of undergrowth plant between 14 and 18 site indices is also great.

Soil biological fertility undergoes fundamental changes when fast-growing exotic trees are planted on a poor savanna soil.

Abstract: Plantations Improve Biodiversity An original vegetation, rich in pioneer species, developed under plantations. Although secondary forest patches occurred among the plantations and could act as a seed source, the floristic composition of the undergrowth was very different from that observed in a nearby forest: most species present in the forest were not found in the plantations, and most species in the plantation undergrowth were absent from the forest plot. The plantations studied were grown on savannas which are not colonised by forest species because annual fires destroy the forest tree seedlings, and where natural evolution from grassland to forest seems not to be possible, unlike the situation described in unburnt Congolese savannas (de Foresta 1990). Commercial tree plantations in a very poor savanna environment bring drastic changes in environmental conditions, due to the reduction of fire occurrence and to the change toward forest microclimate and forest soil. These changes allow plant diversity increase in understorey vegetation, as observed elsewhere in afforested degraded lands such as mined sites or abandoned pastures (Lugo 1997; Parrotta et al. J997; Powers et al. 1997), although Parrotta and Knowles (1999) showed that changes were faster when native species were planted instead of exotic species. In unlogged eucalypt plantations, the general trends with plantation age were an increase ofspecies number, forest species percentage, woody cover density, height and basal area. In managed commercial plantations, the species richness was higher, mainly due to the abundance of savanna and ruderal species, and height and basal area were lower. Further studies should examine the role of the natural forest and the conditions for seed dissemination, germination and seedling growth in plantations' undergrowth. Some results, especially the relationships between soil C, soil pH, and either the number ofundergrowth species or the percentage of forest species, suggested that the changing soil environment through organic matter accumulation could promote the establishment of the undergrowth. This biodiversity, unwanted by foresters, could improve soil functioning by increasing the diversity of organic sources for soil biota and by decreasing the negative effect of eucalypt litter

A discussion on the application of plant physiological model to the hydro climatic effects of forest

Abstract:  The role which plant physiological simulation can play in the assessment of the effects of forests(and their undergrowth) on hydrology and climates is analyzed．This is an essential practice because of the complexity of forest structure function and the landscape． Forests are parti cularly important in soil conservation on steep slopes but it is at the expense of water supply to downstream areas． Plant physiological models should be used in combination with models of soil and meteorological processes．

Dynamics of nitrogen and phosphorus concentrations of fine roots in a mixed forest of Cunninghamia lanceolata and Tsoongiodendron odorum

Abstract: From September 1999 to July 2000, N and P concentrations of fine roots were measured with the method of sequential soil core at bimonthly intervals in a mixed forest of Tsoong's tree (Tsoongiodendron odorum Chun) and Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) in Sanming, Fujian. The results showed that N, P concentration of Chinese fir and Tsoong's tree in fine roots were negatively related to root diameter size. The concentrations of N and P in living roots and dead roots were compared. The order of N concentration in fine roots in different samples was Tsoong's tree>undergrowth>Chinese fir, while that of P was undergrowth>Tsoong's tree>Chinese fir. For Chinese fir, the seasonal change of N, P concentrations in fine roots with various diameter classes showed a single-apex curve with a maximum in September. For Tsoong's tree, maximized concentration of N in fine roots appeared in July or September and maximized P concentration in May.

The carbon-pooling ability of the forest in Wuling mountain natural reserve

Abstract: By using the report of the third forest resource inve stigation of Wuli ng Mountain Natural Reserve and the data from the researching panel of plant an d synecology of Wuling Mountain Natural Reserve,this paper makes an estimate ab out the carbon-pooling ability of the forest of Wuling Mountain Natural Reserve The results showed that the total amount of carbon pooled by the forest in Wuli ng Mountain Natural Reserve is 1676×104t The total amount of carbon pooled by each hectare, in softwood forest, is more than that in broadleaf forest And in the same forest with the change of the type of the resource the amount of poo led carbon is changed with the forest tree at the top, the undergrowth at the bo ttom and the litter in the middle The net amount of carbon pooled by the forest in Wuling Mountain Natural Reserve is 43×104t per year And with the change of the type of forest the net amount of pooled carbon is also changed with the softwood forest at the top, broadleaf forest at the bottom and the theropencedry mion in the middle The economic benefit of the total amount of the pooled carbo n of the forest in Wuling Mountain Natural Reserve is 550 000 000 Yuan RMB