174
airborne RS. Using two case studies, one in a clonal aspen (Populus tremuloides)
forest system and one in a manipulated grassland biodiversity experiment, we demonstrate that plant foliar traits and vegetation cover, as measured via plant spectra
(Wang et al. 2019), can provide critical information predictive of belowground
processes.
8.2 How Are Belowground Processes and Microbial
Communities Influenced by Aboveground Properties?
Belowground processes—including decomposition and nutrient cycling, which are
mediated by microbial biomass, composition, and diversity—are heavily influenced
by both the amount and chemistry of aboveground inputs. Quantifying the amount
and quality of foliar components is a major aspect of trait-based ecology, which
seeks to use functional traits, rather than taxonomic classification, to determine
organisms’ contributions to communities and ecosystems. Trait-based ecology has
inherent strengths, including the ability to consider biological variation across both
phylogenetic and spatial scales (Funk et al. 2017). While there is a range of accepted
trait-based approaches in plant sciences (Funk et al. 2017), the emergence of the
leaf economic spectrum (Wright et al. 2004) and the whole plant economic spectrum (Reich 2014) has clearly demonstrated that plant traits are important to ecosystem processes across multiple biological and spatial scales. Further, employing a
trait-based approach to explore the relationships among plant function, biodiversity,
and belowground processes allows us to take advantage of recent advances in RS to
accurately measure plant traits across large spatial scales.
A. Decomposition and Nutrient Cycling—The productivity, composition, and
diversity of aboveground communities influence belowground processes, in part
through decomposition of leaf litter (Gartner and Cardon 2004; Hättenschwiler
et al. 2005), root litter (Bardgett et al. 2014; Laliberté 2017), and root exudates
(Hobbie 2015; Cline et al. 2018) and also through effects on soil organic matter
(SOM) properties (Mueller et al. 2015) and soil physical structure (Gould et al.
2016). Several seminal reviews outlining the importance of biodiversity to ecosystem function (BEF) have focused specifically on the afterlife effects of litter
diversity on decomposition (Hättenschwiler et al. 2005; Gessner et al. 2010).
B. Microbial Community Composition—Variation in the quantity and quality of
organic inputs into belowground systems drives variation in belowground
microbial communities and functioning (de Vries et al. 2012). Differences in
aboveground communities are mirrored by those in belowground communities
(Wardle et al. 2004; De Deyn and van der Putten 2005; Kardol and Wardle
2010). Across multiple spatial and taxonomic scales, variation in belowground
microbial communities is driven by variation in plant traits associated with the
leaf economic spectrum (de Vries et al. 2012). In general, fungi dominate
decomposition of complex, low-quality substrates, while bacteria favor labile,
high-quality substrates (Fig. 8.1, Bossuyt et al. 2001; Lauber et al. 2008).
M. Madritch et al.
airborne RS. Using two case studies, one in a clonal aspen (Populus tremuloides)
forest system and one in a manipulated grassland biodiversity experiment, we demonstrate that plant foliar traits and vegetation cover, as measured via plant spectra
(Wang et al. 2019), can provide critical information predictive of belowground
processes.
8.2 How Are Belowground Processes and Microbial
Communities Influenced by Aboveground Properties?
Belowground processes—including decomposition and nutrient cycling, which are
mediated by microbial biomass, composition, and diversity—are heavily influenced
by both the amount and chemistry of aboveground inputs. Quantifying the amount
and quality of foliar components is a major aspect of trait-based ecology, which
seeks to use functional traits, rather than taxonomic classification, to determine
organisms’ contributions to communities and ecosystems. Trait-based ecology has
inherent strengths, including the ability to consider biological variation across both
phylogenetic and spatial scales (Funk et al. 2017). While there is a range of accepted
trait-based approaches in plant sciences (Funk et al. 2017), the emergence of the
leaf economic spectrum (Wright et al. 2004) and the whole plant economic spectrum (Reich 2014) has clearly demonstrated that plant traits are important to ecosystem processes across multiple biological and spatial scales. Further, employing a
trait-based approach to explore the relationships among plant function, biodiversity,
and belowground processes allows us to take advantage of recent advances in RS to
accurately measure plant traits across large spatial scales.
A. Decomposition and Nutrient Cycling—The productivity, composition, and
diversity of aboveground communities influence belowground processes, in part
through decomposition of leaf litter (Gartner and Cardon 2004; Hättenschwiler
et al. 2005), root litter (Bardgett et al. 2014; Laliberté 2017), and root exudates
(Hobbie 2015; Cline et al. 2018) and also through effects on soil organic matter
(SOM) properties (Mueller et al. 2015) and soil physical structure (Gould et al.
2016). Several seminal reviews outlining the importance of biodiversity to ecosystem function (BEF) have focused specifically on the afterlife effects of litter
diversity on decomposition (Hättenschwiler et al. 2005; Gessner et al. 2010).
B. Microbial Community Composition—Variation in the quantity and quality of
organic inputs into belowground systems drives variation in belowground
microbial communities and functioning (de Vries et al. 2012). Differences in
aboveground communities are mirrored by those in belowground communities
(Wardle et al. 2004; De Deyn and van der Putten 2005; Kardol and Wardle
2010). Across multiple spatial and taxonomic scales, variation in belowground
microbial communities is driven by variation in plant traits associated with the
leaf economic spectrum (de Vries et al. 2012). In general, fungi dominate
decomposition of complex, low-quality substrates, while bacteria favor labile,
high-quality substrates (Fig. 8.1, Bossuyt et al. 2001; Lauber et al. 2008).
M. Madritch et al.