title: Unimodal relationship between biomass and species richness of deep-sea nematodes: implications for the link between productivity and diversity

authors: Leduc, Daniel

subjects: Biomass

abstract: Describing large-scale patterns of biological diversity is a first step towards understanding the mechanisms that generate and maintain diversity. The highly diverse deep-sea floor is the largest ecosystem on Earth, but the productivity-diversity relationship in this biome is not well characterized. We investigated this relationship by using biomass of nematodes as a proxy for productivity (particulate organic carbon flux to the seabed). We used sample data collected from the New Zealand and Antarctic regions and combined these with published data from around the globe for broader analyses. There was a significant unimodal relationship between nematode biomass and diversity, i.e. expected number of species, ES(51) both within the New Zealand region and across ocean basins. This relationship remained significant after accounting for the effects of both water depth and nematode abundance. These findings support earlier suggestions of a unimodal productivity-diversity relationship in the deep sea that were based on other proxies (e.g. water depth, modelled particulate organic carbon flux). We argue that the 'productivity context' is of primary importance when determining the strength and nature of the relationship between other environmental factors and diversity. Studies that include either or both extremes of the productivity scale are likely to find that productivity is the main factor limiting deep-sea diversity, whereas those focusing on the intermediate productivity range are more likely to find that other factors (e.g. disturbance, habitat heterogeneity) play a role

text: Unimodal relationship between biomass and species richness of deep-sea nematodes: implications for the link between productivity and diversity Describing large-scale patterns of biological diversity is a first step towards understanding the mechanisms that generate and maintain diversity. The highly diverse deep-sea floor is the largest ecosystem on Earth, but the productivity-diversity relationship in this biome is not well characterized. We investigated this relationship by using biomass of nematodes as a proxy for productivity (particulate organic carbon flux to the seabed). We used sample data collected from the New Zealand and Antarctic regions and combined these with published data from around the globe for broader analyses. There was a significant unimodal relationship between nematode biomass and diversity, i.e. expected number of species, ES(51) both within the New Zealand region and across ocean basins. This relationship remained significant after accounting for the effects of both water depth and nematode abundance. These findings support earlier suggestions of a unimodal productivity-diversity relationship in the deep sea that were based on other proxies (e.g. water depth, modelled particulate organic carbon flux). We argue that the 'productivity context' is of primary importance when determining the strength and nature of the relationship between other environmental factors and diversity. Studies that include either or both extremes of the productivity scale are likely to find that productivity is the main factor limiting deep-sea diversity, whereas those focusing on the intermediate productivity range are more likely to find that other factors (e.g. disturbance, habitat heterogeneity) play a role

year: 2012

title: Empower innovations in routine soil testing

authors: Reijneveld, Jan Adriaan

abstract: Conventional soil tests are commonly used to assess single soil characteristics. Thus, many different tests are needed for a full soil fertility/soil quality assessment, which is laborious and expensive. New broad-spectrum soil tests offer the potential to assess many soil characteristics quickly, but often face challenges with calibration, validation, and acceptance in practice. Here, we describe the results of a 20 year research program aimed at overcoming the aforementioned challenges. A three-step approach was applied: (1) selecting and establishing two contrasting rapid broad-spectrum soil tests, (2) relating the results of these new tests to the results of conventional soil tests for a wide variety of soils, and (3) validating the results of the new soil tests through field trials and communicating the results. We selected Near Infrared Spectroscopy (NIRS) and multi-nutrient 0.01 M CaCl2 extraction (1:10 soil to solution ratio; w/v) as broad-spectrum techniques. NIRS was extensively calibrated and validated for the physical, chemical, and biological characteristics of soil. The CaCl2 extraction technique was extensively calibrated and validated for ‘plant available’ nutrients, often in combination with the results of NIRS. The results indicate that the accuracy of NIRS determinations is high for SOM, clay, SOC, ECEC, Ca-CEC, N-total, sand, and inorganic-C (R2 ≥ 0.95) and good for pH, Mg-CEC, and S-total (R2 ≥ 0.90). The combination of the CaCl2 extraction technique and NIRS gave results that related well (R2 > 0.80) to the results of conventional soil tests for P, K, Mg, Na, Mn, Cu, Co, and pH. In conclusion, the three-step approach has revolutionized soil testing in The Netherlands. These two broad-spectrum soil tests have improved soil testing; have contributed to increased insights into the physical, chemical, and biological characteristics of soil; and have thereby led to more sustainable soil management and cropping systems.

text: Empower innovations in routine soil testing Conventional soil tests are commonly used to assess single soil characteristics. Thus, many different tests are needed for a full soil fertility/soil quality assessment, which is laborious and expensive. New broad-spectrum soil tests offer the potential to assess many soil characteristics quickly, but often face challenges with calibration, validation, and acceptance in practice. Here, we describe the results of a 20 year research program aimed at overcoming the aforementioned challenges. A three-step approach was applied: (1) selecting and establishing two contrasting rapid broad-spectrum soil tests, (2) relating the results of these new tests to the results of conventional soil tests for a wide variety of soils, and (3) validating the results of the new soil tests through field trials and communicating the results. We selected Near Infrared Spectroscopy (NIRS) and multi-nutrient 0.01 M CaCl2 extraction (1:10 soil to solution ratio; w/v) as broad-spectrum techniques. NIRS was extensively calibrated and validated for the physical, chemical, and biological characteristics of soil. The CaCl2 extraction technique was extensively calibrated and validated for ‘plant available’ nutrients, often in combination with the results of NIRS. The results indicate that the accuracy of NIRS determinations is high for SOM, clay, SOC, ECEC, Ca-CEC, N-total, sand, and inorganic-C (R2 ≥ 0.95) and good for pH, Mg-CEC, and S-total (R2 ≥ 0.90). The combination of the CaCl2 extraction technique and NIRS gave results that related well (R2 > 0.80) to the results of conventional soil tests for P, K, Mg, Na, Mn, Cu, Co, and pH. In conclusion, the three-step approach has revolutionized soil testing in The Netherlands. These two broad-spectrum soil tests have improved soil testing; have contributed to increased insights into the physical, chemical, and biological characteristics of soil; and have thereby led to more sustainable soil management and cropping systems.

year: 2022-01-01

title: The centrality of relationships for pedagogy: The Whanaungatanga Thesis

authors: Bishop, Russell

subjects: addressing educational disparities

abstract: Te Kotahitanga is a research and professional development project that seeks to reduce educational disparities between indigenous Māori students and their non-Māori peers in New Zealand secondary schools. While evidence of the impact of the project on teachers’ practice and the associated gains made by Māori students has been published previously, in order for the work of Te Kotahitanga to contribute to the broader educational research community, its pedagogical premises require empirical verification. To do so, we must first establish the validity of the pedagogical data by addressing two questions: (a) To what degree can the data gathered in the collaborative processes of Te Kotahitanga be used as a measure of pedagogical quality? and (b) Do these data support the foundational hypothesis of the project, that “extended family” relationships, as understood by Māori people when using the Māori term, whanaungatanga, are a central necessary component of overall pedagogical quality? This article provides an account of the context of this work then presents an analysis directed to these questions in turn. First, our analysis of the observational data gathered during the Te Kotahitanga professional development process is presented, followed by the measures that were developed for each of the main dimensions of pedagogy addressed in this work. Second, using these measures we present our analysis of the inter-relation among these dimensions of pedagogy to test the Whanaungatanga pedagogical thesis.

text: The centrality of relationships for pedagogy: The Whanaungatanga Thesis Te Kotahitanga is a research and professional development project that seeks to reduce educational disparities between indigenous Māori students and their non-Māori peers in New Zealand secondary schools. While evidence of the impact of the project on teachers’ practice and the associated gains made by Māori students has been published previously, in order for the work of Te Kotahitanga to contribute to the broader educational research community, its pedagogical premises require empirical verification. To do so, we must first establish the validity of the pedagogical data by addressing two questions: (a) To what degree can the data gathered in the collaborative processes of Te Kotahitanga be used as a measure of pedagogical quality? and (b) Do these data support the foundational hypothesis of the project, that “extended family” relationships, as understood by Māori people when using the Māori term, whanaungatanga, are a central necessary component of overall pedagogical quality? This article provides an account of the context of this work then presents an analysis directed to these questions in turn. First, our analysis of the observational data gathered during the Te Kotahitanga professional development process is presented, followed by the measures that were developed for each of the main dimensions of pedagogy addressed in this work. Second, using these measures we present our analysis of the inter-relation among these dimensions of pedagogy to test the Whanaungatanga pedagogical thesis.

year: 2013