# Sugar Maple and Red Maple Face-Off: Which Produces More and Sweeter Sap?
## 1 Introduction  
In Canada, and particularly in Quebec, maple hold an emblematic place and play a major economic and cultural role. The country has built a special industry around this species, namely, the production of maple syrup and its derived products, supporting local economies through job creation and sustainable agricultural practices, fostering economic stability and growth in maple-producing regions [1, 2]. Quebec is the world's largest maple producer, accounting for 89.9% of the syrup production in Canada [3]. Maple syrup is an international industry, with production and consumption extending far beyond its North American origin [4]. Nowadays, maple syrup is consumed in more than 50 countries worldwide [5]. Over time, the maple industry in North America has shown robust growth, with >60 M trees tapped in 2022 [6]. This expansion is driven by the rising market, but is challenged by the uncertainties of a changing climate. Fluctuating weather patterns and altered seasons impact sap flow and production schedules, necessitating adaptive strategies to sustain yields and quality to face environmental changes. There are about 150 species of mangles on Earth, but only a dozen are native to North America [7]. Among these, the most commonly tapped species for syrup production are sugar maple (_Acer saccharum_ Marsh. ), its close genetic relative black maple (_Acer nigrum_ F. Michx. ), red maple (_Acer rubrum_ L.), and, to a lesser extent, silver maple (_Acer saccharum_ L.) [6, 8]. The primary factor driving the wide use of these species in the maple industry isthe high sugar content of their sap, which is an essential trait for a sustainable production of high-quality syrup [9; 10; 11]. Among species, the sugar maple is favored by producers as an iconic species for the industry [12; 13; 14]. This preference is mainly due to some expected differences in sap yield and sugar content between species, particularly between sugar maple and red maple [6]. However, these differences between species could be due to the effects of microsite conditions and still remain to be quantified and confirmed experimentally. Yet, a deeper understanding of these differences is essential for providing clear guidance to producers on managing their sugarbushes effectively, as well as for developing strategies to adapt the industry to the future climate scenarios. The distinctions between sugar maple and red maple extend beyond sap yield and chemical composition. These differences also include significant ecological variations that are crucial for their current and future roles in the maple syrup industry. Both species are primarily found in the northeastern United States and southeastern Canada, the core of maple syrup production. Particularly at higher latitudes, these species frequently coexist within the same stands. However, their pronounced ecological differences have important implications for their management. Sugar maple can form stands pure or mixed with other hardwoods and conifers [15]. This species grows in rich and fertile soils and is affected by adverse conditions such as pollution and soil compaction [16; 17]. Red maple is widespread throughout the deciduous forests of eastern North America, extending into the boreal forest borders [18; 19]. Unlike sugar maple, red maple rarely forms pure stands, and adapts to a wide range of environmental conditions. Indeed, red maple is commonly considered more versatile than sugar maple, as it can thrive on a broader spectrum of soil types, textures, moisture, and pH [17; 20; 21]. While optimal growth conditions occur in moist, fertile, loamy soils, it also manages well in dry, rocky, upland sites [20; 21]. This high versatility of red maple could potentially enhance its competitive success compared to sugar maple and contribute to its expansion in response to climate change. Sugar maple is the most abundant species of the maple syrup industry, but other maple species, notably red maple, represent potential alternative syrup sources.