Eucalyptus Short-Rotation Management Effects on Nutrient and Sediments in Subtropical Streams

Abstract

Forested catchments generally present conserved aquatic ecosystems without anthropogenic disturbances; however, forest management operations can degrade these environments, including their water quality. Despite the potential degradation, few studies have analyzed the effects of forest management in subtropical regions, especially in forest plantations with intensive management, such as Eucalyptus plantations in Brazil. The intensive management of those plantations is characterized by fast-growing, short rotation cycles, and high productivity. This study aimed to assess the effects of Eucalyptus plantations harvesting on the concentration and exportation of nutrients and suspended solids in subtropical streams. Results showed that clear-cut harvesting and subsequent forest management operations do not alter most of the concentration of nitrate, potassium, calcium, and magnesium. The concentration of suspended solids increased during the first year after timber harvesting in all studied catchments, however, the increases were statistically significant in only two catchments. In the first year after harvest, it was observed an increment of water yield/precipitation ratio at three catchments, which also increased export of nutrients and suspended solids. Our results showed that harvesting of fast-growing Eucalyptus forest plantations partially affected sediment exports and did not compromise water quality in the studied catchments. However, the catchment land-use design, especially related to road density and land-use composition, showed significant relationship with sediment exportation.

Native forest cover safeguards stream water quality under a changing climate

“…A recent review of studies conducted in Brazil suggests that the lower impact of plantation forestry on water quality compared to other crops could mostly be attributed to improved management practices (Mello et al 2020). Furthermore, eucalyptus plantations only accounted for a modest percentage of the total watershed area in our study region (Appendix S1: Table S2) and the management of these plantations have little effect on water quality, especially if these are not located within or near riparian areas (Binkley et al 1999, Rodrigues et al 2019.…”

“…Nonnative tree cover, namely eucalyptus plantations, did not have significant negative impacts on water quality. This is not surprising since sediment export from planted forests is common only during harvesting periods (Van Dijk and Keenan 2007) or in landscapes where roads are built to facilitate timber extraction (Rodrigues et al 2019). A recent review of studies conducted in Brazil suggests that the lower impact of plantation forestry on water quality compared to other crops could mostly be attributed to improved management practices (Mello et al 2020).…”

Managing Forests and Water for People under a Changing Environment

“…These studies cover a large physiographic gradient across major continents and climatic zones including the temperate rainforests in Chile [1][2][3] and the subtropical forests in Brazil [4] and South America; temperate rainforests [5] and boreal forests [6] in North America; and the large tropical Mekong River Basin in Vietnam [7], the Nenjian River in the boreal northeastern China [8], and the arid Loess Plateau in northern China [9], in east Asia. Five papers addressed issues of the effects of water quantity and quality of native forest buffers on dissolved organic matter in forested and agricultural watersheds in northwestern Patagonia [1]; effects of eucalyptus management on nutrient and sediments in small watersheds in Brazil [4]; effects of pine and eucalyptus plantation forests on water supply for large watersheds (>200 km 2 ) in south central Chile [3]; effects of forests and wetlands on water yield, surface runoff and baseflow in northeastern China [8], and the combined effects of climate and afforestation on soil moisture in Loess Plateau of China [9]. Five papers addressed management issues: Managing headwater streams under climate change [5]; local communities' participation in watershed management [2]; the nexus of forests, water, and policy [10]; ecosystem services in the Mekong River Basin [7] and; risk assessment of wildland fires in Alberta, Canada [6].…”

Managing Forests and Water for People under a Changing Environment

“…The Forest-Water Network: Planning tools This book represents a collection of some of the peer-reviewed papers presented at the Conference that are published in a special issue in Forests (https://www.mdpi.com/journal/forests/special_issues/ Forests_Water). These studies cover a large physiographic gradient across major continents and climatic zones including the temperate rainforests in Chile [1][2][3] and the subtropical forests in Brazil [4] and South America; temperate rainforests [5] and boreal forests [6] in North America; and the large tropical Mekong River Basin in Vietnam [7], the Nenjian River in the boreal northeastern China [8], and the arid Loess Plateau in northern China [9], in east Asia. Five papers addressed issues of the effects of water quantity and quality of native forest buffers on dissolved organic matter in forested and agricultural watersheds in northwestern Patagonia [1]; effects of eucalyptus management on nutrient and sediments in small watersheds in Brazil [4]; effects of pine and eucalyptus plantation forests on water supply for large watersheds (>200 km 2 ) in south central Chile [3]; effects of forests and wetlands on water yield, surface runoff and baseflow in northeastern China [8], and the combined effects of climate and afforestation on soil moisture in Loess Plateau of China [9].…”