BUGS in the Analysis of Biodiversity Experiments: Species Richness and Composition Are of Similar Importance for Grassland Productivity

The idea that species diversity can influence ecosystem functioning has been controversial and its importance relative to compositional effects hotly debated. Unfortunately, assessing the relative importance of different explanatory variables in complex linear models is not simple. In this paper we assess the relative importance of species richness and species composition in a multilevel model analysis of net aboveground biomass production in grassland biodiversity experiments by estimating variance components for all explanatory variables. We compare the variance components using a recently introduced graphical Bayesian ANOVA. We show that while the use of test statistics and the R2 gives contradictory assessments, the variance components analysis reveals that species richness and composition are of roughly similar importance for primary productivity in grassland biodiversity experiments

Global change effects on plant communities are magnified by time and the number of global change factors imposed

Global change drivers (GCDs) are expected to alter community structure and consequently, the services that ecosystems provide. Yet, few experimental investigations have examined effects of GCDs on plant community structure across multiple ecosystem types, and those that do exist present conflicting patterns. In an unprecedented global synthesis of over 100 experiments that manipulated factors linked to GCDs, we show that herbaceous plant community responses depend on experimental manipulation length and number of factors manipulated. We found that plant communities are fairly resistant to experimentally manipulated GCDs in the short term (<10 y). In contrast, long-term (≥10 y) experiments show increasing community divergence of treatments from control conditions. Surprisingly, these community responses occurred with similar frequency across the GCD types manipulated in our database. However, community responses were more common when 3 or more GCDs were simultaneously manipulated, suggesting the emergence of additive or synergistic effects of multiple drivers, particularly over long time periods. In half of the cases, GCD manipulations caused a difference in community composition without a corresponding species richness difference, indicating that species reordering or replacement is an important mechanism of community responses to GCDs and should be given greater consideration when examining consequences of GCDs for the biodiversity–ecosystem function relationship. Human activities are currently driving unparalleled global changes worldwide. Our analyses provide the most comprehensive evidence to date that these human activities may have widespread impacts on plant community composition globally, which will increase in frequency over time and be greater in areas where communities face multiple GCDs simultaneously

Impacts of biodiversity loss escalate through time as redundancy fades

Plant diversity generally promotes biomass production, but how the shape of the response curve changes with time remains unclear. This is a critical knowledge gap because the shape of this relationship indicates the extent to which loss of the first few species will influence biomass production. Using two long-term (≥13 years) biodiversity experiments, we show that the effects of diversity on biomass productivity increased and became less saturating over time. Our analyses suggest that effects of diversity-dependent ecosystem feedbacks and interspecific complementarity accumulate over time, causing high-diversity species combinations that appeared functionally redundant during early years to become more functionally unique through time. Consequently, simplification of diverse ecosystems will likely have greater negative impacts on ecosystem functioning than has been suggested by short-term experiments

Carbon sequestration potential of spotted gum (Corymbia citriodora subspecies Variegata) in south east Queensland, Australia

The objectives of this study were to determine the carbon sequestration potential of spotted gum forest plantation in the South East Queensland region and to determine the suitability of the whole area to carbon sequestration endeavour. This information is indispensable to stakeholders when considering land use options particularly carbon sequestration. A process-based model and geographic information system were employed in the process. The site has a potential biomass production of 1422–2329 ton/ha with the carbon dioxide equivalent range from 2539 to 4157 ton/ ha in 100 year of rotation period. The maximum mean annual growth of 19.98m3 ha1 was estimated in the Great Sandy sub-region while the lowest value of 11.46m3 ha1 was predicted in South Burnett sub-region. The findings indicated that the whole region has a high potential carbon sequestration capability but requires further spatial suitability and economic analysis

Asynchrony among local communities stabilises ecosystem function of metacommunities

Temporal stability of ecosystem functioning increases the predictability and reliability of ecosystem services, and understanding the drivers of stability across spatial scales is important for land management and policy decisions. We used species-level abundance data from 62 plant communities across five continents to assess mechanisms of temporal stability across spatial scales. We assessed how asynchrony (i.e. different units responding dissimilarly through time) of species and local communities stabilised metacommunity ecosystem function. Asynchrony of species increased stability of local communities, and asynchrony among local communities enhanced metacommunity stability by a wide range of magnitudes (1–315%); this range was positively correlated with the size of the metacommunity. Additionally, asynchronous responses among local communities were linked with species’ populations fluctuating asynchronously across space, perhaps stemming from physical and/or competitive differences among local communities. Accordingly, we suggest spatial heterogeneity should be a major focus for maintaining the stability of ecosystem services at larger spatial scales

Extreme drought impacts have been underestimated in grasslands and shrublands globally.

Climate change is increasing the frequency and severity of short-term (~1 y) drought events-the most common duration of drought-globally. Yet the impact of this intensification of drought on ecosystem functioning remains poorly resolved. This is due in part to the widely disparate approaches ecologists have employed to study drought, variation in the severity and duration of drought studied, and differences among ecosystems in vegetation, edaphic and climatic attributes that can mediate drought impacts. To overcome these problems and better identify the factors that modulate drought responses, we used a coordinated distributed experiment to quantify the impact of short-term drought on grassland and shrubland ecosystems. With a standardized approach, we imposed ~a single year of drought at 100 sites on six continents. Here we show that loss of a foundational ecosystem function-aboveground net primary production (ANPP)-was 60% greater at sites that experienced statistically extreme drought (1-in-100-y event) vs. those sites where drought was nominal (historically more common) in magnitude (35% vs. 21%, respectively). This reduction in a key carbon cycle process with a single year of extreme drought greatly exceeds previously reported losses for grasslands and shrublands. Our global experiment also revealed high variability in drought response but that relative reductions in ANPP were greater in drier ecosystems and those with fewer plant species. Overall, our results demonstrate with unprecedented rigor that the global impacts of projected increases in drought severity have been significantly underestimated and that drier and less diverse sites are likely to be most vulnerable to extreme drought

Asynchrony among local communities stabilises ecosystem function of metacommunities

Temporal stability of ecosystem functioning increases the predictability and reliability of ecosystem services, and understanding the drivers of stability across spatial scales is important for land management and policy decisions. We used species-level abundance data from 62 plant communities across five continents to assess mechanisms of temporal stability across spatial scales. We assessed how asynchrony (i.e. different units responding dissimilarly through time) of species and local communities stabilised metacommunity ecosystem function. Asynchrony of species increased stability of local communities, and asynchrony among local communities enhanced metacommunity stability by a wide range of magnitudes (1-315%); this range was positively correlated with the size of the metacommunity. Additionally, asynchronous responses among local communities were linked with species' populations fluctuating asynchronously across space, perhaps stemming from physical and/or competitive differences among local communities. Accordingly, we suggest spatial heterogeneity should be a major focus for maintaining the stability of ecosystem services at larger spatial scales

Asynchrony among local communities stabilises ecosystem function of metacommunities

Temporal stability of ecosystem functioning increases the predictability and reliability of ecosystem services, and understanding the drivers of stability across spatial scales is important for land management and policy decisions. We used species-level abundance data from 62 plant communities across five continents to assess mechanisms of temporal stability across spatial scales. We assessed how asynchrony (i.e. different units responding dissimilarly through time) of species and local communities stabilised metacommunity ecosystem function. Asynchrony of species increased stability of local communities, and asynchrony among local communities enhanced metacommunity stability by a wide range of magnitudes (1–315%); this range was positively correlated with the size of the metacommunity. Additionally, asynchronous responses among local communities were linked with species’ populations fluctuating asynchronously across space, perhaps stemming from physical and/or competitive differences among local communities. Accordingly, we suggest spatial heterogeneity should be a major focus for maintaining the stability of ecosystem services at larger spatial scales.Fil: Wilcox, Kevin R.. Oklahoma State University; Estados UnidosFil: Tredennick, Andrew T.. State University of Utah; Estados UnidosFil: Koerner, Sally E.. University of North Carolina; Estados UnidosFil: Grman, Emily. Eastern Michigan University; Estados UnidosFil: Hallett, Lauren M.. University of Oregon; Estados UnidosFil: Avolio, Meghan L.. University Johns Hopkins; Estados UnidosFil: La Pierre, Kimberly J.. Smithsonian Environmental Research Center; Estados UnidosFil: Houseman, Gregory R.. Wichita State University; Estados UnidosFil: Forest, Isbell. University of Minnesota; Estados UnidosFil: Johnson, David Samuel. Virginia Institute of Marine Science; Estados UnidosFil: Alatalo, Juha M.. Qatar University; QatarFil: Baldwin, Andrew H.. University of Maryland; Estados UnidosFil: Bork, Edward W.. University of Alberta; CanadáFil: Boughton, Elizabeth H.. MacArthur Agroecology Research Center; Estados UnidosFil: Bowman, William D.. University of Colorado; Estados UnidosFil: Britton, Andrea J.. James Hutton Institute; Estados UnidosFil: Cahill, James F.. University of Alberta; CanadáFil: Collins, Scott L.. University of New Mexico; Estados UnidosFil: Du, Guozhen. Lanzhou University; ChinaFil: Eskelinen, Anu. Helmholtz Centre for Environmental Research; Alemania. German Centre for Integrative Biodiversity Research; Alemania. University of Oulu; FinlandiaFil: Gough, Laura. Towson University; Estados UnidosFil: Jentsch, Anke. University of Bayreuth; AlemaniaFil: Kern, Christel. United States Forest Service; Estados UnidosFil: Klanderud, Kari. Norwegian University of Life Sciences; NoruegaFil: Knapp, Alan K.. Colorado State University; Estados UnidosFil: Kreyling, Juergen. Greifswald University; AlemaniaFil: Luo, Yiqi. Oklahoma State University; Estados Unidos. Northern Arizona University; Estados Unidos. Tsinghua University; ChinaFil: McLaren, James E.. University of Texas at El Paso; Estados UnidosFil: Megonigal, Patrick. Smithsonian Environmental Research Center; Estados UnidosFil: Onipchenko, Vladimir. Moscow State Lomonosov University; RusiaFil: Prevéy, Janet. Pacific Northwest Research Station; Estados UnidosFil: Price, Jodi N.. Charles Sturt University; AustraliaFil: Robinson, Clare H.. University of Manchester; Reino UnidoFil: Sala, Osvaldo Esteban. Arizona State University; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía; ArgentinaFil: Smith, Melinda D.. Colorado State University; Estados UnidosFil: Soudzilovskaia, Nadejda A.. Leiden University; Países BajosFil: Souza, Lara. Oklahoma State University; Estados UnidosFil: Tilman, David. University of Minnesota; Estados UnidosFil: White, Shannon R.. Government of Alberta; CanadáFil: Xu, Zhuwen. Chinese Academy of Sciences; República de ChinaFil: Yahdjian, María Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía; ArgentinaFil: Yu, Qiang. Chinese Academy of Agricultural Sciences; ChinaFil: Zhang, Pengfei. Lanzhou University; ChinaFil: Zhang, Yunhai. Chinese Academy of Sciences; República de China. University Aarhus; Dinamarc