An inter-continental comparison between the environmental histories of two lake catchment systems in montane environments of France and South West China

Abstract

Inter-continental comparisons of environmental histories can improve understanding of environmental problems and hazards, and suggest possible actions to promote adaptive capacity and resilience in communities. This article presents evidence from two discrete studies incorporating the same integrated interdisciplinary methodology that look at montane foothill environments in France and South West China. The focus of research is on reconstructing the environmental histories of two lake catchment systems, Annecy in Haute-Savoie, France, and Erhai in Yunnan province, China. The initial findings from the comparison point to very similar sequences of an emergent flood problem in the late 17th to early 18th centuries related to upland land-use transformations of different origins that act upon longer-term sequences of environmental change. Flood problems in both catchments have been met by major engineering solutions that, whilst similar to some extent, differ in technical ingenuity. What this comparison makes clear is the importance of microvariation in environments within these catchments leading to similar, though not the same, adaptive responses to the environment. While it is clear that cultural nuances can be important causes of differences in environmental decision making, particularly in respect to choice and management options, but often the responses tend to be fairly consistent in their approaches to both environmental opportunities and problems.

Detecting climatic signals in an anthropogenically disturbed catchment: The late-Holocene record from the Petit Lac d’Annecy, French Alps

“…Here we attempt to discern a climate signal from lake sediment proxies of geomorphic processes in the Petit Lac d'Annecy catchment, which has been subject to varying land use over the late Holocene, in order to explore whether non-linear geomorphic processes are as pervasive a signal-shredding mechanism as recently claimed. The impact of land-use change on geomorphic processes is already well established for this area (Crook et al, 2002(Crook et al, , 2004(Crook et al, , 2011Dearing, 1979Dearing, , 2001Dearing et al, 2001;Debret et al, 2010;Foster et al, 2003;Giguet-Covex et al, 2011;Higgitt et al, 1991;Noel et al, 2001;Thorndycraft et al, 1998) but previous studies of the Petit Lac d'Annecy catchment have been unable to discern the impact of climate change in the lake sediment record. Here we analyze a new high-resolution data set and apply a novel statistical approach to identify the impact of precipitation change in driving catchment dynamics during the late Holocene.…”

“…Environmental pressures peaked again in the 18th century, when arable farming fell into decline, with reduced soil fertility, increased flood damage and further land abandonment. Historical records point to widespread evidence for increased flooding and soil degradation across over the next 200 years (Crook et al, 2002(Crook et al, , 2004(Crook et al, , 2011Mougin, 1914). The impact of flooding across the catchment was exacerbated by continued clear-felling, a practice that peaked in ad 1840 when forest cover declined to < 3500 ha from a high of 6157 ha in ad 1730 (Crook et al, 2002(Crook et al, , 2004.…”

“…By the start of the 20th century, successive flood remediation schemes had modified all three river systems and many of the upland torrent systems, which had either been straightened, deepened and where necessary dyked (e.g. Crook et al, 2002Crook et al, , 2011. The main river systems are now confined in their lower reaches; with reduced storage capacity across the floodplain and overbank deposition minimal.…”

“…When the monthly precipitation data are summed to give total annual precipitation, significant cross-correlation remains at a 36 yr lag . Data from two periods 1700 bc to ad 2000 (panels a-g) and the last three centuries, ad 1700-2000 (panels h-n) are presented, subdivided into seven historical periods following Crook et al (2002Crook et al ( , 2004Crook et al ( , 2011. Selected pollen profiles are used to reconstruct past land-cover change including forest cover (total arboreal pollen excluding Alnus (AP%)) and agricultural activity (e.g.…”

“…The initial phase of agricultural development spans the Bronze, Iron and Roman periods and is characterised by lowland crop production and forest clearance at both low and high altitude (Crook et al, 2004, 2011). The onset of upland forest clearance is linked to the development of high-altitude alpages for grazing starting in the Bronze/Iron Age (Crook et al, 2011). A similar pattern of upland clearance is recorded at upland sites across the European Alps at this time (e.g.…”