177
from forested biomes in their allocation patterns of NPP (Litton et al. 2007). There
are also large differences in above- and belowground linkages according to site
fertility. In fertile sites the majority of NPP returned to the soil as labile fecal matter,
whereas in infertile systems most NPP returned as recalcitrant plant litter (Wardle
et al. 2004).
8.3.2 Chemical Composition of Vegetation
Beyond variation in total organic inputs to soil, variation in plant chemical composition is critical to belowground ecosystem processes. The physiological traits that
comprise the plant economic spectrum developed by Wright et al. (2004) have
important afterlife affects for belowground systems (Cornwell et al. 2008; Freschet
et al. 2012; see review by Bardgett 2017). Variation in litter chemical quality can
produce marked, long-term effects on litter decomposition rates and nutrient cycling
in underlying soils, and litter quality has long been identified as key factor in determining decomposition rates (Tenney and Waksman 1929). Litter chemistry generally mirrors canopy chemistry (Hättenschwiler et al. 2008), making canopy
chemistry a viable metric to estimate litter chemistry and subsequent belowground
decomposition and nutrient cycling patterns. Aside from aboveground biomass, leaf
nitrogen (N) and lignin content are often the dominant plant traits that drive variation in belowground process, particularly leaf litter decomposition (Aber and
Mellilo 1982; Cadisch and Giller 1997), and both of these traits are readily derived
from spectroscopy at multiple scales (Wessman et al. 1988; Serbin et al. 2014;
Schweiger et al. 2018; Wang et al. 2019). RS of additional leaf traits important to
belowground processes, such as plant secondary chemistry, is also increasingly
measured via RS techniques (Kokaly et al. 2009; Asner et al. 2014; Serbin et al.,
this issue).
Nitrogen Foliar N is often the most important leaf trait driving variation in decomposition across biomes (Diaz et al. 2004; Cornwell et al. 2008; Handa et al. 2014).
In some biomes leaf N is the only known leaf trait associated with leaf decomposition among wide ranges of species (Jo et al. 2016). Because canopy N has a tight
correlation with plant carbon capture through photosynthesis, aboveground biomass,
and belowground processes such as decomposition and N cycling rates, it is among
the most common canopy traits measured via RS platforms (Martin and Aber 1997;
Wessmen et al. 1998; Kokaly and Clark 1999; Martin et al. 1998, 2008; Ollinger
et al. 2002; Townsend et al. 2003; Kokaly et al. 2009; Vitousek et al. 2009; Ollinger
et al. 2013).
Leaf N is directly linked to plant productivity because most plant N is associated with metabolically active proteins, including RuBisCo. Leaf N content is
driven by a trade-off between the benefits of increased photosynthetic potential and
the costs associated with acquiring N along with the increased risk of herbivory
(Diaz et al. 2016). In addition, leaf N can be indicative of plant growth strategies
8 Linking Foliar Traits to Belowground Processes
from forested biomes in their allocation patterns of NPP (Litton et al. 2007). There
are also large differences in above- and belowground linkages according to site
fertility. In fertile sites the majority of NPP returned to the soil as labile fecal matter,
whereas in infertile systems most NPP returned as recalcitrant plant litter (Wardle
et al. 2004).
8.3.2 Chemical Composition of Vegetation
Beyond variation in total organic inputs to soil, variation in plant chemical composition is critical to belowground ecosystem processes. The physiological traits that
comprise the plant economic spectrum developed by Wright et al. (2004) have
important afterlife affects for belowground systems (Cornwell et al. 2008; Freschet
et al. 2012; see review by Bardgett 2017). Variation in litter chemical quality can
produce marked, long-term effects on litter decomposition rates and nutrient cycling
in underlying soils, and litter quality has long been identified as key factor in determining decomposition rates (Tenney and Waksman 1929). Litter chemistry generally mirrors canopy chemistry (Hättenschwiler et al. 2008), making canopy
chemistry a viable metric to estimate litter chemistry and subsequent belowground
decomposition and nutrient cycling patterns. Aside from aboveground biomass, leaf
nitrogen (N) and lignin content are often the dominant plant traits that drive variation in belowground process, particularly leaf litter decomposition (Aber and
Mellilo 1982; Cadisch and Giller 1997), and both of these traits are readily derived
from spectroscopy at multiple scales (Wessman et al. 1988; Serbin et al. 2014;
Schweiger et al. 2018; Wang et al. 2019). RS of additional leaf traits important to
belowground processes, such as plant secondary chemistry, is also increasingly
measured via RS techniques (Kokaly et al. 2009; Asner et al. 2014; Serbin et al.,
this issue).
Nitrogen Foliar N is often the most important leaf trait driving variation in decomposition across biomes (Diaz et al. 2004; Cornwell et al. 2008; Handa et al. 2014).
In some biomes leaf N is the only known leaf trait associated with leaf decomposition among wide ranges of species (Jo et al. 2016). Because canopy N has a tight
correlation with plant carbon capture through photosynthesis, aboveground biomass,
and belowground processes such as decomposition and N cycling rates, it is among
the most common canopy traits measured via RS platforms (Martin and Aber 1997;
Wessmen et al. 1998; Kokaly and Clark 1999; Martin et al. 1998, 2008; Ollinger
et al. 2002; Townsend et al. 2003; Kokaly et al. 2009; Vitousek et al. 2009; Ollinger
et al. 2013).
Leaf N is directly linked to plant productivity because most plant N is associated with metabolically active proteins, including RuBisCo. Leaf N content is
driven by a trade-off between the benefits of increased photosynthetic potential and
the costs associated with acquiring N along with the increased risk of herbivory
(Diaz et al. 2016). In addition, leaf N can be indicative of plant growth strategies
8 Linking Foliar Traits to Belowground Processes