title: Forest canopy restoration has indirect effects on litter decomposition and no effect on denitrification

authors: Wallace, Kiri Joy

subjects: Science & Technology

abstract: Forest restoration has potential to recover degraded ecosystem functions in disturbed environments. Decomposition and denitrification are two critical functions involved in forest nutrient cycling that are often compromised in degraded ecosystems. As forest canopy structure develops following initial plantings, it may indirectly impact ecosystem functions by altering abiotic conditions. It is likely, however, that there are other abiotic factors that affect decomposition and denitrification that are unrelated to forest canopy structure. Here, we aimed to determine whether forest canopy openness, topography, and soil sand content would affect litter decomposition and denitrification by regulating the microclimate, the herbaceous plant layer, soil chemistry, and soil moisture. Research occurred in restored native temperate rainforest patches in two New Zealand cities. Urban forests are an excellent context for measuring impact of canopy restoration on ecosystem properties such as microclimate due to the extreme swings in city conditions (e.g., urban heat island). Decomposition rates were determined using leaf litter bags and denitrification rates through denitrification enzyme activity assays. We used structural equation modeling to quantify the direct and indirect drivers of these ecosystem functions. Results indicated that decomposition rates were positively related to soil moisture, relative humidity, and herbaceous plant cover. Interestingly, forest canopy openness indirectly affected decomposition through counteracting forces, meaning greater canopy openness in young forests permitted dense herbaceous plant growth which enhanced decomposition, while less canopy openness in older forests enhanced humidity levels which increased decomposition. Denitrification was negatively related to soil pH and positively related to soil moisture, but these abiotic factors were unrelated to the forest canopy. Discovering drivers of ecosystem functions can improve approaches to the restoration of degraded ecosystems, especially in disturbed urban areas. Identifying counteracting effects on ecosystem functions could improve management by focusing restoration actions on specific drivers to elicit desired changes. Some ecosystem processes, like denitrification, are not affected by forest canopy restoration or management, but are instead driven by edaphic and landscape factors.

text: Forest canopy restoration has indirect effects on litter decomposition and no effect on denitrification Forest restoration has potential to recover degraded ecosystem functions in disturbed environments. Decomposition and denitrification are two critical functions involved in forest nutrient cycling that are often compromised in degraded ecosystems. As forest canopy structure develops following initial plantings, it may indirectly impact ecosystem functions by altering abiotic conditions. It is likely, however, that there are other abiotic factors that affect decomposition and denitrification that are unrelated to forest canopy structure. Here, we aimed to determine whether forest canopy openness, topography, and soil sand content would affect litter decomposition and denitrification by regulating the microclimate, the herbaceous plant layer, soil chemistry, and soil moisture. Research occurred in restored native temperate rainforest patches in two New Zealand cities. Urban forests are an excellent context for measuring impact of canopy restoration on ecosystem properties such as microclimate due to the extreme swings in city conditions (e.g., urban heat island). Decomposition rates were determined using leaf litter bags and denitrification rates through denitrification enzyme activity assays. We used structural equation modeling to quantify the direct and indirect drivers of these ecosystem functions. Results indicated that decomposition rates were positively related to soil moisture, relative humidity, and herbaceous plant cover. Interestingly, forest canopy openness indirectly affected decomposition through counteracting forces, meaning greater canopy openness in young forests permitted dense herbaceous plant growth which enhanced decomposition, while less canopy openness in older forests enhanced humidity levels which increased decomposition. Denitrification was negatively related to soil pH and positively related to soil moisture, but these abiotic factors were unrelated to the forest canopy. Discovering drivers of ecosystem functions can improve approaches to the restoration of degraded ecosystems, especially in disturbed urban areas. Identifying counteracting effects on ecosystem functions could improve management by focusing restoration actions on specific drivers to elicit desired changes. Some ecosystem processes, like denitrification, are not affected by forest canopy restoration or management, but are instead driven by edaphic and landscape factors.

year: 2018

title: On D-inverse constellations: An alternative view of ordered groupoids

authors: Hughes, Kaden

abstract: A groupoid is a category in which every arrow has an inverse. The ESN (Ehresmann-Schein-Nambooripad) theorem states that the category of inverse semigroups is isomorphic to the category of inductive groupoids, which are groupoids with additional order-theoretic structure. Inductive groupoids are special types of ordered groupoids; the latter shares most of the properties of inductive groupoids but do not correspond to any type of semigroup. Despite this, many of the main facts about inverse semigroups carry over to ordered groupoids, and ordered groupoids have been shown to be an important tool in the study of inverse semigroups. Since then, it has been found that a particular type of partial algebra we call D-inverse constellations are equivalent to ordered groupoids, but have an arguably simpler, purely algebraic definition. This thesis will explore and illustrate the value of working with D-inverse constellations rather than ordered groupoids, presenting an alternative formulation and proof of the ESN Theorem using D-inverse constellations.

text: On D-inverse constellations: An alternative view of ordered groupoids A groupoid is a category in which every arrow has an inverse. The ESN (Ehresmann-Schein-Nambooripad) theorem states that the category of inverse semigroups is isomorphic to the category of inductive groupoids, which are groupoids with additional order-theoretic structure. Inductive groupoids are special types of ordered groupoids; the latter shares most of the properties of inductive groupoids but do not correspond to any type of semigroup. Despite this, many of the main facts about inverse semigroups carry over to ordered groupoids, and ordered groupoids have been shown to be an important tool in the study of inverse semigroups. Since then, it has been found that a particular type of partial algebra we call D-inverse constellations are equivalent to ordered groupoids, but have an arguably simpler, purely algebraic definition. This thesis will explore and illustrate the value of working with D-inverse constellations rather than ordered groupoids, presenting an alternative formulation and proof of the ESN Theorem using D-inverse constellations.

year: 2024-04-13

title: Māori language procreation on social media

authors: Keegan, Te Taka Adrian Gregory

abstract: The Māori language has taken seed and grown on social media. This presentation will examine this presence, exploring the forms it has taken and the influence it is having. It will look at Facebook groups devoted to the Māori language and the birth of the 'Māhuru Māori' (Māori September) movement. It will consider the increasing use of the Māori language on Twitter especially Tweets around a 'kaupapa' (shared purpose). It will also report some anecdotal evidence regarding the use of the Māori language on SnapChat, WhatsApp, and Messenger.

text: Māori language procreation on social media The Māori language has taken seed and grown on social media. This presentation will examine this presence, exploring the forms it has taken and the influence it is having. It will look at Facebook groups devoted to the Māori language and the birth of the 'Māhuru Māori' (Māori September) movement. It will consider the increasing use of the Māori language on Twitter especially Tweets around a 'kaupapa' (shared purpose). It will also report some anecdotal evidence regarding the use of the Māori language on SnapChat, WhatsApp, and Messenger.

year: 2019