title: Intensive development of New Zealand’s indigenous grasslands: Rates of change, assessments of vulnerability and priorities for protection

authors: Weeks, Emily Sherra

subjects: conservation planning

abstract: Research was undertaken in the indigenous tussock grasslands of South Island of New Zealand in order to quantify past rates of conversion to agricultural land use and to develop vulnerability models to predict future conversion spatially and temporally. The study area was delineated using the median spectral reflectance of indigenous grasslands and included the largest extent of unprotected contiguous grasslands concentrated in the central South Island. Conversion from indigenous grasslands to a non-indigenous cover was quantified by comparative mapping over three intervals (1840-1990, 1990-2001, and 2001-2008). The basic premise in using satellite imagery to detect changes in land-use/cover is that these are revealed by changes in spectral signature. However, New Zealand’s indigenous and non-indigenous grasslands have overlapping spectral trajectories and high inter-annual variability, therefore contextual information was needed in order accurately map conversion from indigenous grassland cover to exotic pasture.

Within the study area around the time of European settlement (1840) there were approximately 3.3 million hectares of indigenous grasslands. Between 1840 and 1990 around 1 million hectares of indigenous grasslands were converted to a non-indigenous cover. The extent of conversion during the preceding time period (1990-2008) was approximately 71,261 ha, of which 72% was converted to pasture and cropland and the remaining 28% to mining, urban settlements and exotic forestry. Although the overall rate of grassland conversion decreased relative to the period of European settlement and 1990, the proportion of remaining indigenous grasslands converted each year increased. Almost two-thirds of post-1990 conversion has occurred in environments with less than 30% indigenous cover remaining, and much is in land classified as non-arable with moderate to extreme limitations to crop, pasture and forestry growth. 

To assess the relative vulnerability of remaining areas of indigenous grassland to intensive land use (mainly intensive pasture production but also exotic conifer plantations, urban use and mining), spatial predictions using Generalized Additive Models (GAMs) were used to establish relationships between two different types of dependent (response) variables (presence or absence of conversion) and potential environmental and proxy socio-economic explanatory variables. The chosen predictors for the final model were used to map conversion probabilities in geographic space. The selected GAMs showed the mean probability of conversion in remaining indigenous grasslands was 0.15 and the mean area of conversion was 116 ha. Habitat that was most vulnerable to conversion was at moderate elevations and on medium slopes, and had previously been classified as being of low suitability for production. 

To interpret the regression models, plots of the partial response curves resulting from the model, and overall contributions of variables to the model, were used. The most important explanatory variables for predicting the probability of conversion in order of ‘alone contribution (the potential for each variable alone to explain conversion) was slope, rainfall, land tenure, distance to roads, proximity to existing agricultural, regional council, and mean annual temperature. Interpretation of the GAMs showed that conversion was negatively related to: slope, rainfall and distance roads; positively related to mean annual temperature; higher in the Otago and Canterbury regions and on privately owned or recently privatized lands, and peaked at intermediate proximity to roads. 

The prediction of the probability of conversion model was cross-validated both spatially and temporally. Temporal cross-validation compared predicted probabilities of conversion against reference maps of observed ‘current’ conversion. Spatial cross-validation evaluated model discrimination between ‘converted’ and ‘not converted’. Temporal and spatial performance was measured using the Receiver Operating Characteristic (ROC), a graphical plot of the true positive rate (sensitivity) as a function of the false positive (1-specificity) for different probability thresholds. For temporal cross-validation there was high correlation between ‘predicted’ and ‘observed’ (ROC = 0.913), and for spatial validation the relationship between the fitted and observed was also high (ROC= 0.921), indicating there was good discrimination between ‘converted’ and ‘not converted’. 

Integrating validated estimates of the probability of conversion (vulnerability) into conservation planning tools is an important component of conservation planning. Comparison of conservation prioritisation outputs with validated estimates of vulnerability of New Zealand’s indigenous grasslands showed variable effectiveness of vulnerability surrogates; one surrogate performed most poorly where vulnerability of grasslands to conversion was greatest and realized probability of protection was lowest. Furthermore, estimates of vulnerability using surrogates underestimated vulnerability on flat land that was closer to roads and overestimated areas on steeper land that was topographically invulnerable to conversion.  

There is an increased disparity between patterns of protection and patterns of conversion indicating that existing conservation planning tools are not effectively targeting the most vulnerable areas of remaining indigenous grasslands. An up-to-date validated vulnerability assessment offered a practical and a responsive technical bridge for the gap between science and implementation. This approach can be applied more widely to provide national models of vulnerability from representative samples of conversion.

text: Intensive development of New Zealand’s indigenous grasslands: Rates of change, assessments of vulnerability and priorities for protection Research was undertaken in the indigenous tussock grasslands of South Island of New Zealand in order to quantify past rates of conversion to agricultural land use and to develop vulnerability models to predict future conversion spatially and temporally. The study area was delineated using the median spectral reflectance of indigenous grasslands and included the largest extent of unprotected contiguous grasslands concentrated in the central South Island. Conversion from indigenous grasslands to a non-indigenous cover was quantified by comparative mapping over three intervals (1840-1990, 1990-2001, and 2001-2008). The basic premise in using satellite imagery to detect changes in land-use/cover is that these are revealed by changes in spectral signature. However, New Zealand’s indigenous and non-indigenous grasslands have overlapping spectral trajectories and high inter-annual variability, therefore contextual information was needed in order accurately map conversion from indigenous grassland cover to exotic pasture.

Within the study area around the time of European settlement (1840) there were approximately 3.3 million hectares of indigenous grasslands. Between 1840 and 1990 around 1 million hectares of indigenous grasslands were converted to a non-indigenous cover. The extent of conversion during the preceding time period (1990-2008) was approximately 71,261 ha, of which 72% was converted to pasture and cropland and the remaining 28% to mining, urban settlements and exotic forestry. Although the overall rate of grassland conversion decreased relative to the period of European settlement and 1990, the proportion of remaining indigenous grasslands converted each year increased. Almost two-thirds of post-1990 conversion has occurred in environments with less than 30% indigenous cover remaining, and much is in land classified as non-arable with moderate to extreme limitations to crop, pasture and forestry growth. 

To assess the relative vulnerability of remaining areas of indigenous grassland to intensive land use (mainly intensive pasture production but also exotic conifer plantations, urban use and mining), spatial predictions using Generalized Additive Models (GAMs) were used to establish relationships between two different types of dependent (response) variables (presence or absence of conversion) and potential environmental and proxy socio-economic explanatory variables. The chosen predictors for the final model were used to map conversion probabilities in geographic space. The selected GAMs showed the mean probability of conversion in remaining indigenous grasslands was 0.15 and the mean area of conversion was 116 ha. Habitat that was most vulnerable to conversion was at moderate elevations and on medium slopes, and had previously been classified as being of low suitability for production. 

To interpret the regression models, plots of the partial response curves resulting from the model, and overall contributions of variables to the model, were used. The most important explanatory variables for predicting the probability of conversion in order of ‘alone contribution (the potential for each variable alone to explain conversion) was slope, rainfall, land tenure, distance to roads, proximity to existing agricultural, regional council, and mean annual temperature. Interpretation of the GAMs showed that conversion was negatively related to: slope, rainfall and distance roads; positively related to mean annual temperature; higher in the Otago and Canterbury regions and on privately owned or recently privatized lands, and peaked at intermediate proximity to roads. 

The prediction of the probability of conversion model was cross-validated both spatially and temporally. Temporal cross-validation compared predicted probabilities of conversion against reference maps of observed ‘current’ conversion. Spatial cross-validation evaluated model discrimination between ‘converted’ and ‘not converted’. Temporal and spatial performance was measured using the Receiver Operating Characteristic (ROC), a graphical plot of the true positive rate (sensitivity) as a function of the false positive (1-specificity) for different probability thresholds. For temporal cross-validation there was high correlation between ‘predicted’ and ‘observed’ (ROC = 0.913), and for spatial validation the relationship between the fitted and observed was also high (ROC= 0.921), indicating there was good discrimination between ‘converted’ and ‘not converted’. 

Integrating validated estimates of the probability of conversion (vulnerability) into conservation planning tools is an important component of conservation planning. Comparison of conservation prioritisation outputs with validated estimates of vulnerability of New Zealand’s indigenous grasslands showed variable effectiveness of vulnerability surrogates; one surrogate performed most poorly where vulnerability of grasslands to conversion was greatest and realized probability of protection was lowest. Furthermore, estimates of vulnerability using surrogates underestimated vulnerability on flat land that was closer to roads and overestimated areas on steeper land that was topographically invulnerable to conversion.  

There is an increased disparity between patterns of protection and patterns of conversion indicating that existing conservation planning tools are not effectively targeting the most vulnerable areas of remaining indigenous grasslands. An up-to-date validated vulnerability assessment offered a practical and a responsive technical bridge for the gap between science and implementation. This approach can be applied more widely to provide national models of vulnerability from representative samples of conversion.

year: 2012

title: Datalog as a parallel general purpose programming language

authors: Cleary, John G.

subjects: computer science

abstract: The increasing available parallelism of computers demands new programming languages that make parallel programming dramatically easier and less error prone. It is proposed that datalog with negation and timestamps is a suitable basis for a general purpose programming language for sequential, parallel and distributed computers.
This paper develops a fully incremental bottom-up interpreter for datalog that supports a wide range of execution strategies, with trade-offs affecting efficiency, parallelism and control of resource usage. Examples show how the language can accept real-time external inputs and outputs, and mimic assignment, all without departing from its pure logical semantics.

text: Datalog as a parallel general purpose programming language The increasing available parallelism of computers demands new programming languages that make parallel programming dramatically easier and less error prone. It is proposed that datalog with negation and timestamps is a suitable basis for a general purpose programming language for sequential, parallel and distributed computers.
This paper develops a fully incremental bottom-up interpreter for datalog that supports a wide range of execution strategies, with trade-offs affecting efficiency, parallelism and control of resource usage. Examples show how the language can accept real-time external inputs and outputs, and mimic assignment, all without departing from its pure logical semantics.

year: 2010-08-27

title: Lost in translation or lack of nuance? Perception of (near-)synonymy of common te reo Māori loanwords in New Zealand English

authors: Pohl, Alexander

abstract: Ongoing contact between languages and their speakers inevitably leads to a flow of words being borrowed from one language into another. Research in the field of language contact has established and documented the kinds of borrowed words that stick in their recipient language (Haspelmath 2009; Winford 2010). However, one question that has received comparatively less attention is how a newly adopted loanword relates to the structure of the existing lexicon it enters. In recent years, language contact research has thus seen a paradigm shift towards an onomasiological perspective (see Anderson et al. 2017; Crombez et al. 2022; Zenner et al. 2023). Within this approach, most studies looking at lexical variation between loanwords and their (near-)synonyms employ corpus linguistics methods (e.g. Onysko & Winter-Froemel 2011; Soares da Silva 2013). However, there is variation in how these corpus studies have investigated loanword meanings, and, to our knowledge, there has been almost no experimental research focussed specifically on the relationship between loanwords and their (near-)synonyms to date. This project presents a large-scale experimental approach from a case-study examining Māori loanwords borrowed into New Zealand English (NZE). NZE presents an unusual language contact situation because it involves a dominant language (NZE) receiving an exceptionally high amount of lexical material (words and phrases) from an Indigenous language: Māori. Further adding to the uniqueness of this contact situation is the fact that only a fraction of the population (<10%) speaks Māori fluently (Statistics New Zealand 2019). Nonetheless, Māori loanwords are ubiquitous, salient, and probably still increasing within the NZE lexicon (Macalister 2007; Trye et al. 2019). One important dimension of this set of borrowings are their semantic characteristics, which straddle three main classes of words: flora and fauna (mānuka ‘tea tree’), material culture (maunga ‘mountain’) and social culture (mana ‘power’).  Here, we report on a Qualtrics experiment devised to probe the perceived relationship between 60 Māori loanwords and their NZE equivalents, as ascertained from published sources. The synonymy judgements were elicited for pairs (e.g. whānau – family) using an analogue slider (ranging from 0 = non-synonymous to 100 = fully synonymous). Data was collected using a three-tiered questionnaire: 1) assessing synonymy of loanwords; 2) eliciting strategies for semantic assessments; and 3) collating background information about participants. Following cleaning and exclusions, the dataset showed a skew towards female participants, and for this reason, we focus our statistical analysis on the core sample containing (n = 170) young women (18-24 years). The results of the synonymy judgements analysis consist of qualitative inspections of box plots in relation to the semantic characteristics of Māori words in question, as well as sociodemographic variables of interest, specifically: years lived in Aotearoa NZ, and a composite score capturing exposure to and attitude towards Māori (TRMO). Preliminary findings suggest that many people think Māori loanwords are (highly) synonymous with NZE lexical alternatives. Our regression analyses exhibit evidence that years lived in Aotearoa NZ (p = 0.0054) and TRMO (p = 8.26e-10) can predict knowledge of Māori words. No statistically significant evidence was found for any predictors regarding the scores of the synonymy judgements; instead, we found that the random effects account for most of the variation. This is indicative of idiosyncratic loanword behaviour, in line with situations where variation is in-flux. These findings will be complemented by qualitative analyses of comments provided by participants in the open answer section (2). The talk will conclude with a summary of contributions to the general understanding of loanword meanings and contact-induced lexical change.

text: Lost in translation or lack of nuance? Perception of (near-)synonymy of common te reo Māori loanwords in New Zealand English Ongoing contact between languages and their speakers inevitably leads to a flow of words being borrowed from one language into another. Research in the field of language contact has established and documented the kinds of borrowed words that stick in their recipient language (Haspelmath 2009; Winford 2010). However, one question that has received comparatively less attention is how a newly adopted loanword relates to the structure of the existing lexicon it enters. In recent years, language contact research has thus seen a paradigm shift towards an onomasiological perspective (see Anderson et al. 2017; Crombez et al. 2022; Zenner et al. 2023). Within this approach, most studies looking at lexical variation between loanwords and their (near-)synonyms employ corpus linguistics methods (e.g. Onysko & Winter-Froemel 2011; Soares da Silva 2013). However, there is variation in how these corpus studies have investigated loanword meanings, and, to our knowledge, there has been almost no experimental research focussed specifically on the relationship between loanwords and their (near-)synonyms to date. This project presents a large-scale experimental approach from a case-study examining Māori loanwords borrowed into New Zealand English (NZE). NZE presents an unusual language contact situation because it involves a dominant language (NZE) receiving an exceptionally high amount of lexical material (words and phrases) from an Indigenous language: Māori. Further adding to the uniqueness of this contact situation is the fact that only a fraction of the population (<10%) speaks Māori fluently (Statistics New Zealand 2019). Nonetheless, Māori loanwords are ubiquitous, salient, and probably still increasing within the NZE lexicon (Macalister 2007; Trye et al. 2019). One important dimension of this set of borrowings are their semantic characteristics, which straddle three main classes of words: flora and fauna (mānuka ‘tea tree’), material culture (maunga ‘mountain’) and social culture (mana ‘power’).  Here, we report on a Qualtrics experiment devised to probe the perceived relationship between 60 Māori loanwords and their NZE equivalents, as ascertained from published sources. The synonymy judgements were elicited for pairs (e.g. whānau – family) using an analogue slider (ranging from 0 = non-synonymous to 100 = fully synonymous). Data was collected using a three-tiered questionnaire: 1) assessing synonymy of loanwords; 2) eliciting strategies for semantic assessments; and 3) collating background information about participants. Following cleaning and exclusions, the dataset showed a skew towards female participants, and for this reason, we focus our statistical analysis on the core sample containing (n = 170) young women (18-24 years). The results of the synonymy judgements analysis consist of qualitative inspections of box plots in relation to the semantic characteristics of Māori words in question, as well as sociodemographic variables of interest, specifically: years lived in Aotearoa NZ, and a composite score capturing exposure to and attitude towards Māori (TRMO). Preliminary findings suggest that many people think Māori loanwords are (highly) synonymous with NZE lexical alternatives. Our regression analyses exhibit evidence that years lived in Aotearoa NZ (p = 0.0054) and TRMO (p = 8.26e-10) can predict knowledge of Māori words. No statistically significant evidence was found for any predictors regarding the scores of the synonymy judgements; instead, we found that the random effects account for most of the variation. This is indicative of idiosyncratic loanword behaviour, in line with situations where variation is in-flux. These findings will be complemented by qualitative analyses of comments provided by participants in the open answer section (2). The talk will conclude with a summary of contributions to the general understanding of loanword meanings and contact-induced lexical change.

year: 2024