Measuring woody debris in the small streams of New Zealand's pine plantations

Abstract

To assess the impact of harvesting on woody debris volumes in streams, a method was required with sufficient precision to provide meaningful evaluation and comparison of pre-and postharvest levels of woody debris. Before harvest, woody debris volumes were measured in 24 first-to third-order stream sites in New Zealand's mature pine plantations (22-34 years of age). An adaptation of the Van Wagner line intersect method was used to measure the small woody debris 1-9 cm in diameter (SWD). All large woody debris 10 cm in diameter (LWD) was measured for diameter and length. Woody debris volumes in the stream channel ranged from 2 to 345 m 3 ha -1 , averaging 112 m 3 ha -1 (±34, 95% confidence interval (CI)). Woody debris surface areas averaged 2883 m 2 ha -1 (±688), range 220-6769 m 2 ha -1 . Most of the woody debris volume (87%) was composed of LWD. Sixty-seven percent of the woody debris volume was located above the stream, the remainder was lying in-stream or on the floodplain. Woody debris volumes in streams of mature pine plantations in New Zealand were similar to woody debris volumes in streams of temperate native forests in New Zealand and North America. These sites will be remeasured after harvest to identify any changes in woody debris characteristics. M98014

Spatial variability of biotic and abiotic factors of the aquatic habitat in French Guiana

“…However, channel width can be locally altered by the presence of large woody debris. This biotic component increases channel width because of accumulation that causes localized flooding, erosion or diverts the river path (Baillie and Cummins, 1999;Bragg and Kershner, 1999). Nevertheless, in our study, narrow channels such as those of the rivers in cluster 1, 3 and 7 are more likely to be influenced by large woody debris than are large channels such as those of the rivers in cluster 5.…”

Spatial distribution and influence of large woody debris in an old-growth forest river system, New Zealand

“…In New Zealand, reach-scale studies to date have examined LWD loadings and influence on stream channel morphology in a number of stream systems, focusing on smaller sized streams in both indigenous and exotic pine plantation forests (Mosley, 1981;Evans et al, 1993;Baillie et al, 1999;Baillie and Davies, 2002;Meleason et al, 2005), but distribution patterns of LWD and morphological influence have not been studied at the catchment level. The objectives of this study were to (a) describe and quantify the amount and spatial distribution of LWD in a large catchment of old-growth forest and (b) determine the influence of LWD on channel morphology and habitat complexity.…”

Material leñoso de gran tamaño en dos cuencas de la Cordillera de la Costa de Chile con diferente historia de uso del suelo

“…La medición de la abundancia de este material en Pichún ocurrió entre tres y cuatro años luego de la cosecha del bosque de P. radiata que cubría la cuenca desde aproximadamente el año 1987, plantación precedida a su vez por una anterior rotación forestal también de esta especie, por lo que el volumen en esta cuenca puede compararse con los registrados en cauces bajo plantaciones de esta conífera. Baillie et al (1999) reportan en 24 cauces de primer a tercer orden bajo plantaciones maduras (22-34 años) de P. radiata en Nueva Zelandia, una abundancia en un rango entre dos y 345 m 3 ha -1 y una media de 112 m 3 ha -1 , pero con siete de las 24 cuencas con valores menores que los 56 m 3 ha -1 medidos en Pichún. En el mismo país y bajo el mismo tipo de plantaciones, Baillie y Davies (2002) entregan la información de otras cinco cuencas donde midieron entre 77 y 200 m 3 ha -1 (media de 127 m 3 ha -1 ).…”