The Effects of Replacing Native Forest on the Quantity and Impacts of In‐Channel Pieces of Large Wood in Chilean Streams

Abstract

Dead trees in rivers can significantly affect their morphological and ecological properties by increasing flow resistance, affecting sediment transport, and storing organic matter. Logs are usually recruited from banks or along the entire upstream basin. Although it is generally acknowledged that forested headwater streams feature higher volumes of in-channel pieces of large wood, the influence of forest type and forest management of the potential recruitment zone on the volumes and effects of wood have been less explored, especially in relation to the effects of replacing native forests with pine plantations. This paper presents a comparison of volumes of wood, and characteristics and effects on streams draining paired basins with comparable slopes, areas, and hydrologic regimes, but different in terms of land use. The five selected pairs of basins are located in the Coastal and Andean mountain Ranges in central Chile, in order to compare native forest and pine plantation basins. The results show that logs tend to be shorter and with larger diameters in streams draining native forest basins. Because of their smaller dimensions, logs and jams tend to be more mobile and oriented parallel to the flow. Volumes of in-channel wood in native forest basins are only slightly larger than in pine plantation basins, and no differences have been identified in terms of morphological effects on channel geometry. Also, fish type and biomass were comparable among pairs. Evidence highlights the importance of the width of riparian buffers in mitigating the effects of land use change, especially the substitution of native forest with plantations.

Long‐term large wood load fluctuations in two low‐order streams in Southern Chile

“…In South America, wood loads were measured in 18 catchments (17 in Chile and 1 in the Argentinean Patagonia), with areas in the range of 1.4–17.8 km 2 with an average value of 209 m 3 ha −1 (range 8–1057 m 3 ha −1 ) and mean respective loads of 269 and 87 m 3 ha −1 for catchments covered by unmanaged native forests and intensively managed plantations ( Pinus radiata , Eucalyptus spp .) (Comiti et al ., 2008; Iroumé et al ., 2010, 2014, 2015; Nizza, 2010; Alvear, 2011; Gómez, 2013; Mao et al ., 2016). In addition, wood loads measured from January to March 2015 along three reaches of the Blanco River (catchment area ~70 km 2 ) affected by the 2008 eruption of Chaitén volcano in Southern Chile ranged from 64 to 122 m 3 ha −1 .…”

Invasive Rainbow Trout (Oncorhynchus mykiss) Are Not Affected by Different Land Uses in a Multi-Use, Mediterranean Climate Landscape

“…In examining which physical features of the site were significantly different in C1-P and A1-P from the rest of the sites [50], likely factors are low slopes, long or deep pools and very low amounts of wood. The presence of N. inermis in these sites is supported by some of the scant literature about the species that describes the optimal habitat for this species.…”

“…Ten of the eleven study sites were selected to represent catchments paired along similar characteristics of slope, aspect, soils, drainage area, catchment orientation, climate, hydrologic regime and proximity (Table 2), allowing us to investigate differences caused by distinct land uses (i.e., native forest vs. pine plantations). For more information about the stream selection process and the physical characteristics of each site, see Mao et al [50].…”

“…The statistical significance and predictive strength were then compared against CPUE [43]. Catch per unit effort (CPUE) (n/500 m 2 ) was calculated by using the estimated abundances for each sampling site [58] and then standardizing them to a constant area, based on field surveys [50]. All statistical assessments were conducted in R [59].…”

The Evaluation of Color Spaces for Large Woody Debris Detection in Rivers Using XGBoost Algorithm

“…In addition, wildfires are increasingly influencing the recruitment of LWD in rivers [1,2]. In several studies [3][4][5], LWD refers to downed and dead wood pieces that are ≥10 cm in diameter and ≥1 m in length. They often alter the topography of rivers [6,7], resistance to flow, flow velocity [8], and sediment transport capacity [8,9]; influence organic matter content [10]; and enhance the biodiversity of habitat and the environment [11].…”