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Surrounding Forest (surrounding + forest)
Selected AbstractsSingle host trees in a closed forest canopy matrix: a highly fragmented landscape?JOURNAL OF APPLIED ENTOMOLOGY, Issue 9-10 2007J. Müller Abstract:, Whether trees represent habitat islands and therefore are influenced by similar biogeographic processes as ,real' islands is controversial. For trees in highly fragmented landscapes the impacts of spatial isolation on arthropod communities have already been demonstrated. However, we have almost no evidence that in large forests the arthropod communities on single trees in a closed canopy matrix are influenced by similar processes. In the present study the influence of spatial isolation on the specialized oak crown fauna was analysed in a large broadleaved forest area in northern Bavaria, Germany. The dependence of specialists on the proportion of oaks in the surrounding forest was investigated by using flight interception traps (67 on oak, 19 on beech). As target species, saproxylic and herbivorous Coleoptera and Heteroptera were sampled. The following two hypotheses were tested: (1) The proportion of oak specialists differs for oaks in beech forests and oaks in oak forests. (2) The proportion of oak specialists increases with the proportion of oaks in the surrounding forest. For all species groups, the proportion of oak specialists was higher in oak crowns than in beech crowns. Herbivorous beetles and true bugs showed a higher proportion of specialists in oak forests than on single oaks in beech forests. The proportion of herbivorous oak specialists increased significantly with increasing numbers of adjacent oak trees, while saproxylic Coleoptera showed no relationship to oak density. For herbivorous Coleoptera a threshold of higher proportion occurred where >30% oak was present, and for Heteroptera a first threshold was identified at values >70% and a second at >30%. This indicates that larger habitat patches within a closed forest canopy matrix support larger populations of herbivorous oak specialists. Hence, similar effects of spatial isolation might occur in a closed forest as have already been shown for highly fragmented open landscapes. [source] Avifauna associated with ephemeral ponds on the Cumberland Plateau, TennesseeJOURNAL OF FIELD ORNITHOLOGY, Issue 2 2006Brett R. Scheffers ABSTRACT Although ephemeral ponds act as small hotspots of plant, invertebrate, and salamander diversity, the importance of such ponds for birds has been little studied. We hypothesized that ephemeral ponds on the Cumberland Plateau in Tennessee would support a greater abundance, richness, and diversity of birds than the surrounding hardwood forests. In 2004, we recorded all birds seen or heard in 10 min within 50-m radius circles at 25 ephemeral ponds. We repeated the counts at control sites located 150 m from each pond in the surrounding forest. To quantify potential food availability, we captured aerial invertebrates using sweep nets at four points around a subsample of eight ephemeral ponds and at an equal number of control sites. We found significantly greater bird abundance, richness, and species diversity at ephemeral ponds than at control sites, and that pond area was not associated with either bird abundance or richness. Bird community composition at pond and control sites was similar. Aerial invertebrates were significantly more abundant at ephemeral ponds than at adjacent forest sites, providing one possible explanation for greater bird abundance at ephemeral ponds. SINOPSIS Aunque las charcas efímeras actúan como lugares claves para plantas, invertebrados y vertebrados como salamandras, la importancia de estas no ha sido objeto de estudio para aves. Pusimos a prueba la hipótesis de que charcas efímeras, sostendrían una mayor abundancia, riqueza y diversidad de aves que unos bosques secundarios encontrados en Cumberland Plateau, Tennessee. Durante el 2004 contabilizamos las aves observadas o escuchadas, durante un periodo de 10 minutos en círculos con radio de 50 m en 18 charcas efímeras. Como control, repetimos los conteos en los alrededores del bosque a distancias de 150 m de las charcas. Para cuantificar la disponibilidad potencial de alimentos, capturamos invertebrados aéreos utilizando redes de barrido en cuatro lugares como sub-muestras en ocho de las charcas y en un número similar de áreas con bosques. Encontramos un número significativo mayor de abundancia de aves, riqueza y diversidad de especies en las charcas efímeras que en los bosques. El área ocupada por las charcas no estuvo asociada ni a la riqueza o abundancia de aves. La composición de la comunidad de aves en las charcas y en los bosques resultó similar. La cantidad de invertebrados aéreos fue significativamente más abundante en las charcas que en los bosques adyacentes, lo que provee una explicación posible para la mayor abundancia de aves en las charcas. [source] Colonization of storm gaps by the spruce bark beetle: influence of gap and landscape characteristicsAGRICULTURAL AND FOREST ENTOMOLOGY, Issue 1 2010Leif Martin Schroeder 1After storm disturbances, there is a risk for degradation of the quality of fallen trees, and for subsequent tree mortality caused by the spruce bark beetle Ips typographus (L.) (Coleoptera: Curculionidae). Models assessing the risk for bark beetle colonization of different kinds of storm gaps would be a valuable tool for management decisions. 2The present study aimed to determine which gap and landscape characteristics are correlated with the probability of colonization of wind-felled Norway spruce trees by I. typographus. 3The study included 36 storm gaps, varying in size from three to 1168 wind-felled spruces, created by the storm Gudrun in southern Sweden in January 2005. 4In the first summer, on average, 5% of the wind-felled spruces were colonized by I. typographus. The percentage of colonized wind-felled trees per gap was negatively correlated with the total area of storm gaps within 2000 m in the surrounding forest landscape. 5In the second summer, the proportion of colonized trees increased to 50%. Both gap (mean diameter of wind-felled trees and basal area of living spruce trees) and landscape variables (amount of spruce forest) were significantly correlated with colonization percentage and explained almost 50% of the variation between gaps. 6There was no relationship between gap area and colonization percentage. This implies that landscapes with many large storm gaps, where logging resources will be most effectively used, should be salvaged first. [source] Vertebrate Fauna Recolonization of Restored Bauxite Mines,Key Findings from Almost 30 Years of Monitoring and ResearchRESTORATION ECOLOGY, Issue 2007Owen G. Nichols Abstract Studies into the processes of vertebrate fauna colonization of Alcoa's restored bauxite mines began around 1975. This recognized the key role of vertebrate fauna in jarrah forest ecosystem processes, and also the fact that some species were rare, so priority was given to determining their status in unmined forest, and promoting their return to restored areas following mining. Long-term studies have since taken place on mammals, birds, and reptiles both in unmined forest and in restored areas of varying ages and techniques. Mammal recolonization varies between species depending on species' food and shelter requirements and their distribution and abundance in the surrounding forest. Birds rapidly recolonize and 95% of species have been recorded in restoration. Bird community structure changes with restoration type and age, and in current restoration, it is similar to that of unmined forest by the age of 10 years. Studies on reptiles have shown that 21 of 24 species have recolonized. The remaining three include one legless lizard and two snakes, all of which feed on small vertebrates (e.g., skinks) and require shelter in the form of logs, stumps, and coarse woody debris. Some other reptile species consistently occur in restoration in lower densities than in unmined forest, and current studies are investigating the causes of this. Together, studies on these three vertebrate fauna groups have provided valuable, complementary information on their habitat requirements, and the extent to which Alcoa's restoration program has been successful in reestablishing this important component of the jarrah forest's biodiversity. [source] | ||||||||||