title: Tree species sorting along temperature gradients: How do frost-resistant traits influence competitive ability in the forest environment?

authors: FitzPatrick, Dominic Luke

subjects: forest ecology

abstract: To thrive in the forest environment a species must be able to pass each of three filters: first it must reach a site (the historical filter), then it must be able to tolerate the physical environment (the physiological filter) and finally it must be able to cope with biotic interactions at the site (the biotic filter). This thesis comprises of two complementary studies that explore the role temperature gradients play in determining a species ability to pass the physiological and biotic filters of a temperate rainforest. These studies were conducted using the seedlings of New Zealand warm- and cool- temperate tree species. The first study addresses how the trade-off in shade tolerance vs. growth rate found throughout closed-canopy forests changes from warm-temperate to cool-temperate environments using a transplant experiment. The second study aims to determine the implications of climate-related variation in xylem anatomy for morphological and physiological traits related to competitive ability. Warm-temperate species were found to be both faster-growing and more shade-tolerant than the cool-temperate species, indicating that cold resistant traits reduce competitive ability in warmer environments. This was supported by findings that the warm-temperate species had more conductive xylem and correspondingly higher levels of leaf area deployed than the cool species, indicating that cold resistance indirectly reduces the leafiness of a species. These cool-temperate species with less leaf surface area are less effective at intercepting light, resulting in lower growth rates and reduced shade tolerance which are important components of competitive ability in tree species. This may explain their absence from warmer forest environments, and their restriction to colder environments.

text: Tree species sorting along temperature gradients: How do frost-resistant traits influence competitive ability in the forest environment? To thrive in the forest environment a species must be able to pass each of three filters: first it must reach a site (the historical filter), then it must be able to tolerate the physical environment (the physiological filter) and finally it must be able to cope with biotic interactions at the site (the biotic filter). This thesis comprises of two complementary studies that explore the role temperature gradients play in determining a species ability to pass the physiological and biotic filters of a temperate rainforest. These studies were conducted using the seedlings of New Zealand warm- and cool- temperate tree species. The first study addresses how the trade-off in shade tolerance vs. growth rate found throughout closed-canopy forests changes from warm-temperate to cool-temperate environments using a transplant experiment. The second study aims to determine the implications of climate-related variation in xylem anatomy for morphological and physiological traits related to competitive ability. Warm-temperate species were found to be both faster-growing and more shade-tolerant than the cool-temperate species, indicating that cold resistant traits reduce competitive ability in warmer environments. This was supported by findings that the warm-temperate species had more conductive xylem and correspondingly higher levels of leaf area deployed than the cool species, indicating that cold resistance indirectly reduces the leafiness of a species. These cool-temperate species with less leaf surface area are less effective at intercepting light, resulting in lower growth rates and reduced shade tolerance which are important components of competitive ability in tree species. This may explain their absence from warmer forest environments, and their restriction to colder environments.

year: 2015

title: Consumption of submerged aquatic macrophytes by rudd (scardinius erythrophthalmus L.) in New Zealand

authors: Lake, Michael D.

subjects: aquatic macrophytes

abstract: In experiments in New Zealand, rudd (Scardinius erythrophthalmus L.) of 108–277mm fork length (FL) ate a wide range of native and introduced submerged aquatic macrophytes in captivity and in the field. Rudd consumed the native charophytes Chara globularis Thuill., Chara fibrosa Ag. ex Bruz., and Nitella spp., the native macrophytes Potamogeton ochreatus Raoul. and Myriophyllum propinquum A. Cunn., and the introduced macrophytes Elodea canadensis Michx., Egeria densa Planch., Lagarosiphon major L., and Ceratophyllum demersum L. Rudd consistently consumed the Nitella spp. and Potamogeton ochreatus before Ceratophyllum demersum. From the results of experiments in tanks and in the field, we found the order of highest to lowest palatability was: Nitella spp. > Potamogeton ochreatus > Elodea canadensis> Chara globularis = Chara fibrosa> Egeria densa = Lagarosiphon major > Myriophyllum propinquum > Ceratophyllum demersum. The order of consumption was subject to some variation with season, especially for Egeria densa, Lagarosiphon major, and Myriophyllum propinquum. Rudd
consumed up to 20% of their body weight per day of Egeria densa in spring, and 22% of their body weight per day of Nitella spp. in summer. Consumption rates were considerably lower in winter than in summer. The results of our field trial suggested that the order of consumption also applies in the field and that rudd are having a profound impact on vulnerable native aquatic plant communities in New Zealand. Nitella spp. and Potamogeton ochreatus are likely to be selectively eaten, and herbivory by rudd might prevent the re-establishment of these species in
restoration efforts.

text: Consumption of submerged aquatic macrophytes by rudd (scardinius erythrophthalmus L.) in New Zealand In experiments in New Zealand, rudd (Scardinius erythrophthalmus L.) of 108–277mm fork length (FL) ate a wide range of native and introduced submerged aquatic macrophytes in captivity and in the field. Rudd consumed the native charophytes Chara globularis Thuill., Chara fibrosa Ag. ex Bruz., and Nitella spp., the native macrophytes Potamogeton ochreatus Raoul. and Myriophyllum propinquum A. Cunn., and the introduced macrophytes Elodea canadensis Michx., Egeria densa Planch., Lagarosiphon major L., and Ceratophyllum demersum L. Rudd consistently consumed the Nitella spp. and Potamogeton ochreatus before Ceratophyllum demersum. From the results of experiments in tanks and in the field, we found the order of highest to lowest palatability was: Nitella spp. > Potamogeton ochreatus > Elodea canadensis> Chara globularis = Chara fibrosa> Egeria densa = Lagarosiphon major > Myriophyllum propinquum > Ceratophyllum demersum. The order of consumption was subject to some variation with season, especially for Egeria densa, Lagarosiphon major, and Myriophyllum propinquum. Rudd
consumed up to 20% of their body weight per day of Egeria densa in spring, and 22% of their body weight per day of Nitella spp. in summer. Consumption rates were considerably lower in winter than in summer. The results of our field trial suggested that the order of consumption also applies in the field and that rudd are having a profound impact on vulnerable native aquatic plant communities in New Zealand. Nitella spp. and Potamogeton ochreatus are likely to be selectively eaten, and herbivory by rudd might prevent the re-establishment of these species in
restoration efforts.

year: 2002

title: Is there a lack of science resources and specialists for kaiako at Kura reo o Waikato?

authors: Hopkins, Aareka

subjects: Kura kaupapa

abstract: The New Zealand debates on culture and science education for Maaori are grounded in the concern for the under-achievement of tauira in science. In 1995, a lack of subject experts, specialists and resources to implement the Ministry of Education’s science curriculum was identified. I investigated the concept of a mobile science laboratory to provide subject experts, specialists and resources to Kura Reo o Tainui as a way of improving and enhancing tauira literacy and engagement in puutaiao. This study used a semi-structured survey to elicit the whakaaro and perceptions of kaiako puutaiao from four Wharekura, three Kura Kaupapa Maaori, and three Rumaki Total Immersion classes in Waikato-Tainui, using registered participants in the inaugural Kura Reo o Tainui Waananga in 2008 to select survey participants.

text: Is there a lack of science resources and specialists for kaiako at Kura reo o Waikato? The New Zealand debates on culture and science education for Maaori are grounded in the concern for the under-achievement of tauira in science. In 1995, a lack of subject experts, specialists and resources to implement the Ministry of Education’s science curriculum was identified. I investigated the concept of a mobile science laboratory to provide subject experts, specialists and resources to Kura Reo o Tainui as a way of improving and enhancing tauira literacy and engagement in puutaiao. This study used a semi-structured survey to elicit the whakaaro and perceptions of kaiako puutaiao from four Wharekura, three Kura Kaupapa Maaori, and three Rumaki Total Immersion classes in Waikato-Tainui, using registered participants in the inaugural Kura Reo o Tainui Waananga in 2008 to select survey participants.

year: 2010-08