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Undergrowth

About: Undergrowth is a research topic. Over the lifetime, 795 publications have been published within this topic receiving 11911 citations. The topic is also known as: understorey & underbrush.


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Journal ArticleDOI
TL;DR: In this paper, the authors used three techniques: visual interpretation (VI), object oriented image segmentation (OOIS) and biophysical modeling (BM) to estimate the forest canopy density.
Abstract: Forest canopy density is an important parameter to assess the ecological conditionsviz, light penetration through canopy, undergrowth, surface reflectance, rainfall interception, etc. in a forest landscape. The rate of change in the cover and density has increased due to human need for fuel and fodder. Hence, quick, repetitive and accurate information about forest density is required at the local, regional, state and national levels for sustainable forest management. Satellite remote sensing has the potential to provide information on the forest canopy closure. The present study aims at forest canopy density mapping using satellite remote sensing data using three techniques: visual interpretation (VI), object oriented image segmentation (OOIS) and biophysical modeling (BM). On comparing the techniques, the BM has been found to be the better density mapping technique than other two in terms of accuracy, efficiency and high correlation with ground estimates.

31 citations

Journal Article
TL;DR: Ten girls, mature at birth, who suffered severe fetal growth retardation, but were without evidence of congenital disease, have been followed serially in growth and development for at least seven years, indicating that severe undergrowth in single-born infants, uncomplicated by acute asphyxia or congenitals disease, may not prejudice later mental development.
Abstract: Ten girls, mature at birth, who suffered severe fetal growth retardation (< third percentile), but were without evidence of congenital disease, have been followed serially in growth and development for at least seven years. The five infants whose head circumferences at 1 year of age were found to be at or below the tenth percentile had, on the average, an IQ of ten points below the five whose head growth had reached the 25th percentile or better. No neurologic handicaps or significant school deficits were encountered in either group. The mean IQ of 103 for the whole group in this small sample indicated that severe undergrowth in single-born infants, uncomplicated by acute asphyxia or congenital disease, may not prejudice later mental development.

30 citations

01 Jan 1987
TL;DR: The increased population subdivision and response to riverine barriers in understory terra firme forest birds suggests that the genetic continuity of these birds will be disrupted severely by the fragmentation of formerly contiguous forest through the building of roads and associated agricultural clearing currently underway in the Amazon basin.
Abstract: The high frequency with which rivers delimit phenotypically differentiated bird taxa is unique to Amazonia, where major rivers often form the boundaries between allospecies and subspecies pairs of understory terra flrme forest birds. In contrast, many such forest species with life history traits similar to these differentiated forms show no variation in plumage across even the largest rivers. To determine whether such species are nonetheless genetically differentiated, I.obtained tissue samples from populations of forest understory birds from opposite banks of the Napo and Amazon rivers of northeastern Peru. These included three species that are not phenotypically differentiated across the Amazon and three species that are not phenotypically differentiated across the Napo, as well as two species that are phenotypically differentiated across the Amazon. Protein electrophoretic analysis of allozymes revealed substantial genetic differences among river-separated birds that do and do not show plumage differences. The prevailing historical hypothesis to explain the high number of species of Amazonian birds states that isolation in Pleistocene forest fragments was the important vicariant event that permitted speciation. An alternative is that Isolation on opposite banks of rivers after the formation of the Amazonian ix river system was the Important vicariant event. The pattern of genetic variation reported in this study supports the latter hypothesis. Wright's coefficient F _ was used as an Indirect index of the ol extent of gene flow among populations in contiguous forest. For some Amazonian species, F ^ values are high compared to' most temperate zone birds, especially considering the geographic proximity (<90 km) among the compared Amazonian populations. Increased population subdivision due to reduced effective population size or reduced effective dispersal distance, coupled with an aversion to crossing habitat discontinuities exposed to full sunlight, could explain the effect of riverine barriers on genetic differentiation within such species. The increased population subdivision and response to riverine barriers in understory terra firme forest birds suggests that the genetic continuity of these birds will be disrupted severely by the fragmentation of formerly contiguous forest through the building of roads and associated agricultural clearing currently underway in the Amazon basin.

30 citations

Journal ArticleDOI
01 Jan 2001
TL;DR: The uniform age of the Hagenia stands suggests that regeneration in these forests occurs suddenly after a disturbing event, and it is assumed, that the reproduction of the subalpine forests depends on occasional burning.
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.

29 citations

Journal ArticleDOI
TL;DR: It is concluded that the stumps play a more important role (relative to their covered area, 21–28 m2ha–1) in terms of suitable microsites for regeneration, than the logs do.
Abstract: Decaying logs and stumps provide an important seedling substrate in natural subalpine forests. However, only stumps present such a role in managed forests. The aim of this study was to assess the differences in the process of seedling colonization between logs and stumps. The study was carried out in the Czech Republic, in two old-growth subalpine spruce forests located in the Bohemian Forest and Ash Mts., dominated by Athyrium distentifolium Opiz and Vaccinium myrtillus L. undergrowth, respectively. Norway spruce (Picea abies (L.) Karst.) regeneration growing on logs, stumps and non-coarse woody debris (CWD) microsites was surveyed. Regeneration (height 0–2.0 m) densities exceeded 5000 individuals per ha on both sites. The average density of P. abies regeneration per square meter of substrate was 0.3-5.719.6 and 0.5-3.8-11.0 on non-CWD microsites, logs and stumps, located in A. distentifolium and V. myrtillus undergrowth, respectively. Stumps and non-CWD microsites dominated by V. myrtillus, supported a higher proportion of taller seedlings per plot compared to the small seedlings growing on logs and non-CWD dominated by A. distentifolium ground-cover. The disproportion in regeneration densities between the stumps and the original logs decreased with increasing stages of decay. The tallest regeneration growing on stumps (root-soil plates) was significantly older than that growing on the logs (stems). Based on these two latter findings, the stumps appeared to provide suitable seedling substrates several years earlier than the logs did. Therefore, we conclude that the stumps play a more important role (relative to their covered area, 21–28 m2ha–1) in terms of suitable microsites for regeneration, than the logs do.

29 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202337
202293
202133
202030
201934
201836