Defining functional biomes and monitoring their change globally

Abstract

Biomes are important constructs for organizing understanding of how the worlds' major terrestrial ecosystems differ from one another and for monitoring change in these ecosystems. Yet existing biome classification schemes have been criticized for being overly subjective and for explicitly or implicitly invoking climate. We propose a new biome map and classification scheme that uses information on (i) an index of vegetation productivity, (ii) whether the minimum of vegetation activity is in the driest or coldest part of the year, and (iii) vegetation height. Although biomes produced on the basis of this classification show a strong spatial coherence, they show little congruence with existing biome classification schemes. Our biome map provides an alternative classification scheme for comparing the biogeochemical rates of terrestrial ecosystems. We use this new biome classification scheme to analyse the patterns of biome change observed over recent decades. Overall, 13% to 14% of analysed pixels shifted in biome state over the 30-year study period. A wide range of biome transitions were observed. For example, biomes with tall vegetation and minimum vegetation activity in the cold season shifted to higher productivity biome states. Biomes with short vegetation and low seasonality shifted to seasonally moisture-limited biome states. Our findings and method provide a new source of data for rigorously monitoring global vegetation change, analysing drivers of vegetation change and for benchmarking models of terrestrial ecosystem function.

Assessing earth system model predictions of C4 grass cover in North America: From the glacial era to the end of this century

“…At regional scales, such as those observed in the present study, the representation of C 4 cover and grass‐dominated vegetation often contrasts with observations. This contrast may be because the distribution of grassy vegetation is often modified by ecosystem ecology and disturbance (Griffith et al, ; Moncrieff et al, ), and biome patterns may not be deterministic but instead contingent on biogeographical and evolutionary history (Higgins, Buitenwerf, & Moncrieff, ; Lehmann et al, ; Moncrieff et al, ).…”

Solar radiation and functional traits explain the decline of forest primary productivity along a tropical elevation gradient

“…However, in order to specifically test for the importance of direct temperature effects on photosynthesis, we used a generic temperature sensitivity model (Higgins et al . ) and compared simulations with and without temperature dependence.…”

Diversification is decoupled from biome fidelity: Acacia – a case study

“…We have shortened the WWF Biome names for brevity, with the original WWF names indicated within brackets: Tropical forest (Tropical and Subtropical Moist Broadleaf Forests), Temperate forest (Temperate Broadleaf and Mixed Forests), Mediterranean (Mediterranean Forests, Woodlands and Scrub), Tropical grassland (Tropical and Subtropical Grasslands, Savannas & Shrublands), Temperate grassland (Temperate Grasslands, Savannas and Shrublands), Montane grassland (Montane Grasslands and Shrublands), and Desert (Deserts and Xeric Shrublands). Functional Biomes (Figure b, Higgins et al, ; Higgins, Buitenwerf, & Moncrieff, ) are also global and based on vegetation attributes quantifiable from satellite imagery: vegetation height (Short or Tall), vegetation productivity index (High, Medium or Low) and seasonality of growth (moisture limited, Dry; cold limited, Cold; moisture and cold limited, Both; or non‐seasonal, Non‐seasonal). Each of the 24 different Functional Biomes represents a different combination of these three vegetation attributes, and 13 of these Functional Biomes occur in Australia: SLD (Short Low Dry), SMD (Short Medium Dry), SHD, (Short High Dry), TMD (Tall Medium Dry), THD (Tall High Dry), SLB (Short Low Both), SMB (Short Medium Both), SLN (Short Low Non‐seasonal), SMN (Short Medium Non‐seasonal), SHN (Short High Non‐seasonal), TLN (Tall Low Non‐seasonal), TMN (Tall Medium Non‐seasonal) and THN (Tall High Non‐seasonal).…”

“…Biomes of Australia showing (a) WWF Biomes (Olson et al, ), (b) Functional Biomes (Higgins et al, ), (c) Crisp Biomes (Crisp et al, ), and (d) González‐Orozco Biomes (González‐Orozco et al, ). The names of the Functional Biomes are a combination of vegetation height (S ‐ Short or T ‐ Tall); vegetation productivity index (L ‐ Low, M ‐ Medium or H ‐ High); and how temperature and soil moisture limit growth seasonally (D ‐ Dry, B ‐ both cold and dry or N ‐ non‐seasonal).…”