Edge Effects in Fragmented Forests: Implications for Conservation

Article (PDF Available)inTrends in Ecology & Evolution 10(2):58-62 · February 1995with 5,558 Reads
DOI: 10.1016/S0169-5347(00)88977-6 · Source: PubMed
Abstract
Edges are presumed to have deleterious consequences for the organisms that remain in forest fragments. However, there is substantial discrepancy among recent studies about the existence and intensity of edge effects. Most studies have focused on seeking simplistic and static patterns. Very few have tested mechanistic hypotheses or explored the factors that modulate edge effects. Consequently,studies are very site-specifci and their results cannot be generalized to produce a universal theory of edges. Although estimates of the intensity and impact of edge effects in fragmented forests are urgently required, little can be done to ameliorate edge effects unless their mechanics are better understood.
  • ... al., 1998;Urbina y Reynoso, 2005) que toleran ambientes más secos y temperaturas más altas (Chen et. al., 1992;Murcia, 1995;Urbina y Reynoso, 2005). ...
    ... El efecto de borde es un fenómeno que se produce entre dos ecosistemas lindantes y cuenta con características únicas que son el resultado de la interacción de las características prevalecientes entre dos sistemas ecológicos y puede funcionar como barreras o como áreas de conexión entre las comunidades (Delcourt, 1992;Gosz, 1992;Murcia, 1995) dependiendo de cómo cada especie percibe y responde a las características ambientales resultantes de la zona (Gosz, 1992;Sekgororoane y Dilwort, 1995), determinándose así que los efectos de borde dependiendo de la respuesta de la fauna pueden ser: positivos, negativos o neutros (Ries et. al., 2004). ...
    ... al., 1997) por lo que la distancia hasta donde se observa el efecto de borde puede ser indicador de la magnitud de la modificación del hábitat. Tal efecto puede originarse de manera natural o por la intervención de las actividades antrópicas (Murcia, 1995). Este fenómeno, sea cual sea su origen, siempre creará fragmentación del hábitat y por consiguiente cambios pequeños o grandes en la biodiversidad. ...
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    Se evaluó la riqueza, abundancia y diversidad de las comunidades de anfibios y reptiles en tres fragmentos de bosque tropical amazónico en la zona de Lumbaquí influenciados por efectos de origen antrópico. Cada fragmento de bosque estuvo constituido por dos ecotonos (borde de bosque e interior de bosque) previamente pre-establecidos. Después de muestrear 18 transectos (9 en el borde y 9 en el interior en los tres fragmentos) se registraron a 390 anfibios pertenecientes a 44 especies (especies de borde: 36 y especies del interior: 31) y 96 reptiles pertenecientes a 28 especies (especies de borde: 17 y especies del interior: 17). De acuerdo a la afinidad de las especies hacia los dos ecotonos en análisis, se determinaron 13 especies de anfibios y 11 especies de reptiles con tendencias generalistas para habitar en el borde. Por el contrario, se determinó a ocho especies de anfibios y 11 especies de reptiles con tendencias especialistas para habitar en el interior del bosque del fragmento. Las similitudes en las pendientes de las curvas de rango-abundancia determinaron que la comunidad de anfibios se constituyó como equitativa entre los ecotonos de estudio, en contraste con los reptiles que según las diferencias en las pendientes de las curvas de rango-abundancia no se constituyeron como comunidades equitativas. A pesar de esto se evidenció una tendencia de especies generalistas de borde como Rhinella margaritifera, R. marina, Adenomera hylaedactyla y Pristimantis diadematus en los anfibios y Hemidactylus mabouia, Potamites ecpleopus y Leposoma parietale en los reptiles. Así mismo se registraron especies especialistas del interior de bosque siendo las más representativas entre los anfibios Noblella myrmecoides, Scinax garbei, Osteocephalus alboguttatus y O. taurinus y entre los reptiles Plica umbra, Enyalioides laticeps, Synophis lasallei y Siphlophis compressus. Finalmente, la prueba estadística SIMPER determinó que las muestras del ecotono interior de bosque fueron más similares entre sí en comparación con las muestras del borde de bosque. La prueba determinó también que las especies Pristimantis aff. librarius, P. lanthanites, P. achuar y P. altamnis fueron las que aportaron mayores porcentajes de contribución para la disimilitud de los ecotonos. Se concluye en que la mayor riqueza y abundancia de especies de anfibios se ve agrupada en el ecotono borde de bosque con 36 especies y 120 individuos a diferencia de los reptiles que registraron en ambos ecotonos 17 especies y una diferencia mínima en su abundancia con 47 y 49 individuos en el borde e interior respectivamente.
  • ... The decreasing of populations size and interruption of their connection is a direct cause of increase of inbreeding and genetic drift, which in turn favour the loss of genetic variation and limit adaptive capacities of populations, increasing their risk of extinction (Murcia 1995;Jules and Rathcke 1999;Jacquemyn et al. 2002). Habitat fragmentation is a progressive dynamic process determining small size disconnected populations (Forman 1995), strongly influencing bio- geographic and ecological changes of the resulting ecosystems ( Saunders et al. 1991), including severe effects on diversity and interactions among species and functions of biotic communities (Klapwijk and Lewis 2008). ...
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  • ... The decreasing of populations size and interruption of their connection is a direct cause of increase of inbreeding and genetic drift, which in turn favour the loss of genetic variation and limit adaptive capacities of populations, increasing their risk of extinction (Murcia 1995;Jules and Rathcke 1999;Jacquemyn et al. 2002). Habitat fragmentation is a progressive dynamic process determining small size disconnected populations (Forman 1995), strongly influencing bio- geographic and ecological changes of the resulting ecosystems ( Saunders et al. 1991), including severe effects on diversity and interactions among species and functions of biotic communities (Klapwijk and Lewis 2008). ...
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  • ... Considering the highway is a man-made structure PR was measured 100m inwards to reduce the possible interference of anthropological disturbance and edge-effects on data (Murcia, 1995). OP was measured 25m inwards as the plantations themselves are man- made structures and differences in edges are likely to be less extreme. ...
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  • ... Recent studies have shown that vegetation and soil recovery in old fields can be affected by proximity to forest edge [5,11,12]. The edge effect is defined as the difference in biotic and abiotic factors that exist at the border of a fragmented habitat relative to the interior environment [12,13]. Increased seed dispersal rates and the creation of microclimates at the natural/old field edge have been reported to favor establishment of plant communities that are different from those found in the old field interior [5,10,14]. ...
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  • ... For example, the increase in luminosity and desiccation in the forest edge leads to an increase in light-loving vegetation and ha- bitat-generalist species ( Laurance et al., 2002). In general, the edge effect is higher in small forest fragments, causing proliferation of sec- ondary vegetation (Murcia, 1995;Laurance et al., 2002) that is asso- ciated with marked increases in abundance of a few common species of insects and vertebrates that thrive by exploiting these changes (Fowler et al., 1993;Hue et al., 2017;Laurance et al., 2002). Usually edge ef- fects reduce habitat quality and causes the decline of diverse groups of animals, such as butterflies, understorey birds and large sized primates ( Laurance et al., 2002). ...
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  • ... Such data have been used to suggest greater emergence and/or survival under ecotones than in other microhabitats. Carolina (1995) noted that this is a type of "direct biological edge effect" where changes in the physical environment caused by edges can directly affect the forest structure. The characteristics of the ecotone have a large impact on both dispersal and plant establishment. ...
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  • ... Urban forest is the ideal context to observe how abiotic properties affect nutrient cycling because of the extreme swings in abiotic conditions in cities. The high edge to interior ratio inherent to small urban forest patches negatively affects an array of properties, such as altered vegetation structure, increased sunlight availability, greater fluctuations in humidity, greater soil compact- ness, and more exposure to pollution (Matlack 1993, Young and Mitchell 1994, Murcia 1995, Harper et al. 2005, Malmivaara-L€ ams€ a et al. 2008). Urban forests are therefore particularly disrupted by edge effects because of their small patch size and isolation, compounded by the altered envi- ronment of the surrounding urban matrix (e.g., asphalt causing the urban heat island; Oke et al. 1989). ...
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