Background
Currently, only limited research has been performed on the hydrological controls of pond hydrochemistry across the Western Boreal Forest, and even less so on how all these controls combine into a single hydrological system. Most research produced in the Western Boreal Forest tends to focus on only one or two main factors within a specific area, never leaving the local scale of research. A major reason for this being that the drier climate, deeper surficial glacial deposits and larger groundwater flow systems of the Western Boreal Forest make generalisations on hydrologic functioning difficult (Devito et al., 2000). This makes it challenging to produce effective management policies on hydrochemistry controls across the region. Yet despite the large variability of the landscape, the Western Boreal Forest is still often viewed as a single Canadian biome.
It has long been recognised that terrestrial processes influence the chemical state of the ponds that reside in it (Summer et al., 1990; Wetzel, 1983). A large amount of knowledge on hydrochemistry and the influence of landscape controls already exists for the Western Boreal Forest, but most of this data is either buried in grey literature (e.g. provincial reports, personal knowledge, unpublished data), or only focuses on the effects of a single control (i.e. climate, bedrock geology, topography, etc.). But in order to allow for proper watershed management and protection, a better understanding of hydrochemical variability and the landscape drivers influencing it is required.
It has long been recognised that terrestrial processes influence the chemical state of the ponds that reside in it (Summer et al., 1990; Wetzel, 1983). A large amount of knowledge on hydrochemistry and the influence of landscape controls already exists for the Western Boreal Forest, but most of this data is either buried in grey literature (e.g. provincial reports, personal knowledge, unpublished data), or only focuses on the effects of a single control (i.e. climate, bedrock geology, topography, etc.). But in order to allow for proper watershed management and protection, a better understanding of hydrochemical variability and the landscape drivers influencing it is required.
Research Objective
The goal of this research is therefore to assess the variability in pond hydrochemistry and determine whether a sufficient amount of this variability can be explained when investigated at the regional scale. More specifically, my main questions are as followed: 1) Is the gathering of such an extensive region under a single biome valid when concerning hydrochemistry, or do distinct regions with unique chemistry exist in the Western Boreal Forest? 2) Is there a single landscape control dominating the variability we see in hydrochemistry at this regional level, are there combined effects, or can no real effects from the landscape be assessed when working at this level in the landscape?
These answers can guide future management, as it proves whether or not highly detailed, intensive analyses at the local landscape scale are required to properly guide watershed and pond management across the Western Boreal Forest. Furthermore, the potential identification of distinct regions of hydrochemistry further guides management, as it provides a baseline in pond chemistry variability and informs which regions allow extrapolation of potential landscape effects.
Using Devito et al.’s (2005) broad scale classification of catchments, I have generalised the dominant hydrologic processes of the landscape to develop a conceptual framework and assessed their influences on hydrochemistry. This framework determines the dominant components of the hydrologic cycle and identifies the scale of interaction that should be considered. My framework consists of a hierarchy of factors nested within each other to characterise the relative importance of different scales and types of hydrologic interactions ranging from local to regional interactions. The orders in which these factors influence hydrologic flow paths are presented as climate, bedrock geology, surficial geology, wetland connectivity, and topography. These different hydrologic flow paths will consequently influence the dominant mechanisms that determine pond hydrochemistry.
These answers can guide future management, as it proves whether or not highly detailed, intensive analyses at the local landscape scale are required to properly guide watershed and pond management across the Western Boreal Forest. Furthermore, the potential identification of distinct regions of hydrochemistry further guides management, as it provides a baseline in pond chemistry variability and informs which regions allow extrapolation of potential landscape effects.
Using Devito et al.’s (2005) broad scale classification of catchments, I have generalised the dominant hydrologic processes of the landscape to develop a conceptual framework and assessed their influences on hydrochemistry. This framework determines the dominant components of the hydrologic cycle and identifies the scale of interaction that should be considered. My framework consists of a hierarchy of factors nested within each other to characterise the relative importance of different scales and types of hydrologic interactions ranging from local to regional interactions. The orders in which these factors influence hydrologic flow paths are presented as climate, bedrock geology, surficial geology, wetland connectivity, and topography. These different hydrologic flow paths will consequently influence the dominant mechanisms that determine pond hydrochemistry.
Expected results
I expected to find only a limited amount of the variability in hydrochemistry to be explained at the level of the Western Boreal Forest. Our sampled ponds are experiencing very different controls from the landscape, due to the Western Boreal Forest being so variable (e.g. permafrost absence/presence, depth to bedrock, etc.) (Fig.2). I expected to find more of my variability to be explained when moving from all of the ponds sampled across the Western Boreal Forest into only those located in the Plains (Boreal and Taiga), thus excluding the effects of topography found in the mountainous region (Boreal Cordillera), and continental groundwater movement experienced by the Plain/Shield transition zone. But even within the Plains, I expected only a limited amount of variability to be explained by my landscape controls, due to strong variability in the landscape at the local scale.
Fig. 2: Map of the Western Boreal Forest with all sampled ponds and the ecozones (TC=Taiga Cordillera, TP=Taiga Plains, TS=Taiga Shield, BC= Boreal Cordillera, BP=Boreal Plain & BS=Boreal Shield). The four panels illustrate the Western Boreal Forest’s variability in A) Permafrost, B) Moisture, C) Bedrock geology and D) Peatland Area across the landscape.