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.

The conservation importance of luxuriant tree plantations for lower storey forest birds in south-west Ghana.

Abstract: Summary The exceptionally rapid degradation and fragmentation of the Upper Guinea Forest, caused by slash-and-burn farming and selective logging, oblige bird conservationists to examine critically the conservation value of unprotected areas, which may provide buffer zones or connecting corridors to protected forests. This paper assesses the utilisation of various tree-crop plantations by mainly lower storey forest birds in south-west Ghana, through avifaunal comparisons of shaded cash crops (rustic cocoa; neglected coconut) and exotic tree plantations (Cedrela, Gmelina) with nearby closed forest. Plantations adjacent to, or within, large (.200 km 2 ), biodiverse forests are superior bird habitats compared to similar plantations within small (,50 km 2 ) and species-poor forests. A relatively high forest tree density in cash crop (15–20 ha 1 ) and exotic (15–35 ha 1 ) tree plantations, combined with a luxuriant woody undergrowth (not slashed for .5–10 years), may additionally explain the presence of many forest specialists, including regionally ‘Vulnerable’ and locally ‘Endangered’ species. Overall, 50% of species of conservation importance found in forests were represented in plantations. These findings highlight the importance of shaded plantations with long periods between understorey weeding, as appropriate land-use systems that enhance the area under effective conservation and improve the connectivity of protected forest fragments. Results are compared to similar studies in the Old and New World tropics, and implications for off-reserve land-use management are compared and discussed in regional and global contexts.

Assessment of Errors Caused by Forest Vegetation Structure in Airborne LiDAR-Derived DTMs

Abstract: Airborne Light Detection and Ranging (LiDAR) is a survey tool with many applications in forestry and forest research. It can capture the 3D structure of vegetation and topography quickly and accurately over thousands of hectares of forest. However, very few studies have assessed how accurately LiDAR can measure surface topography under forest canopies, which may be important, for example, in relation to analysis of pre- and post-burn surface height maps used to quantify the combustion of organic soils. Here, we use ground survey equipment to assess digital terrain model (DTM) accuracy in a deciduous broadleaf forest, during both leaf-on and leaf-off conditions. Using the leaf-on LiDAR dataset we quantitatively assess vertical vegetation structure, and use this as a categorical explanatory variable for DTM accuracy. In the presence of leaf-on vegetation, DTM accuracy is severely reduced, with low-stature undergrowth vegetation (such as ferns) causing the greatest errors (RMSE > 1 m). Errors are lower under leaf-off conditions (RMSE = 0.22 m), but still of a magnitude similar to that reported for mean depths of burn in fires involving organic soils. We highlight the need for adequate ground control schemes to accompany any forest-based airborne LiDAR survey which require highly accurate DTMs.

Genetic diversity and microgeographic differentiation of Yushan cane (Yushania niitakayamensis; Poaceae) in Taiwan

Abstract: Yushan cane (Yushania niitakayamensis) is distributed in southeast Asia. In Taiwan, the species occurs in mountains 1000–3600 m above sea level. The species appears to spread mainly by rhizomes and flowers only rarely. Nine locations across its distribution range in Taiwan were sampled. Locations at higher altitudes generally consist of grassland and forest undergrowth habitats while those of lower altitudes generally consist of forest undergrowth only. Thus two sampling sites (montane grassland and forest undergrowth) were selected from each location at higher altitudes while only one sampling site was selected from each location at lower altitudes, resulting in a total of 13 sampling sites. Within each sampling site, 20 individual plants were sampled. The results of the cluster analysis and the principal coordinate analysis based on random amplified polymorphic DNA (RAPD) indicated that the populations are generally differentiated according to geographical separation and altitudinal differences that interrupt gene flow. The populations at higher altitudes, where the species is distributed somewhat contiguously, were found to be more similar genetically. Analysis of molecular variance (AMOVA) revealed that the among-location, between sampling sites within location, and among individuals within sampling site components accounted for 15.27%, 4.80% and 79.93% of the total variance, respectively. For locations with two sampling sites, two-level AMOVA revealed that the diversities between sampling sites (sun and shade habitats) within locations ranged from 2.91% to 7.99% of the total diversity. Random permutation tests revealed that these diversities were significant, implying that there is microgeographic differentiation due to habitat differences.

Early Succession Following Clearcutting of Aspen Communities in Northern Utah.

Abstract: Changes in aspen reproduction and undergrowth production and composition were recorded over a 3-year period following clearcutting. Aspen suckers increased from 2,300 per hectare prior to cutting to a maximum of 44,000 per hectare the second post-cut year, and dropped to approximately 25,000 per hectare by the third year. Undergrowth production on the cut units increased from 1,013 kg/ha prior to cutting to 3,000 kg/ha after three growing seasons; production on the uncut control areas increased from 1,199 kg/ha to 1,539 kg/ha during this period. The significant increase in undergrowth is attributed to the reduction in competition from the removal of the aspen overstory. Clearcutting appeared to increase the proportion of shrubs in the undergrowth and decrease the proportion of forbs. A similarity index comparing the cut and uncut areas suggested that the greatest change in species composition occurred the first year after cutting, with a gradual return towards the precut conditions. The extensive aspen (Populus tremuloides) forests found at intermediate elevations in the intermountain Rocky Mountain West are highly valued multiple-use lands. They are noted for production of livestock forage, wildlife habitat, and scenic beauty, and they are a potentially valuable source of wood products. Through the process of natural plant succession many of these forests are becoming dominated by conifers, frequently within a single aspen generation. Such conversion concerns resource managers because it is usually accompanied by substantial reductions in forage and wildlife habitat. As a consequence, considerable interest has developed in periodically setting back the process of succession in order to maintain communities that are dominated by aspen. Prescribed burning and clearcutting are the 2 main management alternatives for halting succession to conifers and regenerating the aspen forest. Both of these methods involve drastic disturbance of the plant community. Intelligent use of either requires that we understand not only the effect of such disturbance upon the trees, but upon other components of the community as well. Burning is a viable alternative for rejuvenating an aspen forest where fuel conditions are amenable to fire and where the trees have little or no commercial value. Recently we published descriptions of early succession following prescribed burning of aspen communities (Bartos and Mueggler 1981). Clearcutting may be desirable either where burning is not feasible or where the value of the wood is sufficient to finance the cutting operation. Although the ability of western aspen to reproduce prolifically following clearcutting is well documented (Jones 1975, Schier 1976, Schier and Smith 1979), very little information is available regarding the changes in undergrowth likely to occur when the tree overstory is removed by clearcutting. This report describes aspen reproduction and changes in undergrowth composition and production over a 3-year period following Authors are range scientist and plant ecologist with the Intermountain Forest and Range Experiment Station, USDA Forest Service, located at the Forestry Sciences Laboratory, 860 N. 12 E. Logan, Utah, 84321. The authors wish to thank Dr. William A. Laycock for his help in the initial design of the study and in sampling in 1973. clearcutting aspen communities on the Wasatch National Forest in northern Utah.

Birds Lost from a Giant Sequoia Forest during Fifty Years

Abstract: Not all forest bird species breeding on Redwood Mountain, Tulare County, California in the 1930s are still there in the 1980s. Over the 50 Years virgin aiant seauoia forest of the saddle and east slope (within Rings Canyon NationalPark) remains unchanged but has lost the Olive-sided Flycatcher (Contopus borealis). The mixture of old and secondgrowth sequoias of Whitaker’s Forest, where pines and undergrowth were removed and snags eliminated, is missing the Mountain Quail (Oreortyx pictus), Flammulated Owl (Otus flammeolus), Northern Pygmy-Owl (Glaucidium gnoma), Spotted Owl (Strix occidentalis), Hairv Woodnecker (Picoides villosus). and Olive-sided Flvcatcher. Thouah unchanaed todav. the Xparian alders of Eshom Creek on the west slope have lost Swainso& Thrush~Catha& ustulatus). Drastic logging by Sequoia National Forest has driven all of the above from the west slope ponderosa pine forest that surrounds Whitaker’s Forest. New birds established at Whitaker’s Forest by 1986 are the Common Raven (Corvus corax), House Wren (Troglodytes aedon), and Lincoln’s Sparrow (Melospiza lincolnii). Intrusion of Brown-headed Cowbirds (Molothrus ater) has begun without yet affecting two abundant species of vireos. The Pileated Woodpecker (Dryocopus pileatus) is reduced; the Winter Wren (Troglodytes troglodytes) has greatly increased. I attempt to explain avifaunal changes by comparing habitats over the 50-year interval. Disappearance of the flycatcher and thrush from unchanged, prime habitat must be caused by destruction of corresponding forests in Central America, where these birds maintain their winter territories.