Gradient Analysis in Nature Reserve Design: A New Zealand Example

Abstract

Absiract: Direct and indirect gradient analysis methods were tested to assist in nature reserve design in New Zealand Graphic descl-iptions were made of community-environment relationships. Environmental factors considered included altitude solar radiation, geologic substrate soil drainage, and landform. Classification identified 21 lowland forest community types in the northwestern South Island study area These community types and their composite species appear to be arranged along soil fertility, landfomz, and temperature gradients. Direct gradient analysis was particularly useful in portraying the relationship of the plant communities to perceived environmental gradients. Comprehensive gradient diagrams for an ecological district may be compared with gradient diagrams depicting the district's current reserves, qany. A representative reserve system may be achieved if 'gaps" between the two diagrams are filled in by expanding the reserve system andlor modifying existing reserve boundaries. Based on this technique a recommendation is made to incorporate a unique coastal forest remnant in a national park proposal for the study area a Species codes: MYRAUS, Myrsine australis (Myrsinuceae) MACEXG Macropiper excelsum (Piperaceae) M O W , Rhopalostylis sapida (Arecaceae) M m , Melicytus ramiflorus (Violaceae) METROB, Metrosideros robusta (Myrtaceae) €€BARB, Hedycarya arborea (Monimiaceae) DACDAC, Dacrycarpus dacrydioides (Podocatpaceae) ELADm, Elaeocarpus dentatus (EZaeaocarpaceae) MYRSU, Myrsine salicina (Mytsinaceae) PRUFEhB, Prumnopitys ferrigineus (Podocatpaceae) WELRAC, Weinmannia racemosa (Cunoniaceae) NOPUS Nothofagus fusca (Fagaceae) NOTME& N. menziesii (Fagaceae) DACCUP, Dacrydium cuppressimum (Podocatpaceae) NOmRG Nothofagus truncata (Fagaceae) PODHAL, Podocarpus hallii (Podocatpaceae) QUISER, Quintinia serrata (Escalloniaceae) METUMB, Metrosideros umbellata (Myrtaceae) P H Y M , Phyllocladus aspleniifolius var. alpinus (Podocatpaceae) NOTSOL, Nothofagus solandri var. cliffortioides (Fagaceae) LEPIm, Lepidothamnus intermedius (Podocatpaceae) LEPSCO, Leptospermum scoparius (Myrtaceae)

Vegetation-environment relationships at Waipoua Forest, Northland, New Zealand

“…Other ordination studies of vegetation-environment relationships in New Zealand have also recognised the importance of differences in soil properties and altitude as the major factors influencing forest composition (Leathwick 1987;Stewart & Harrison 1987;DeVelice et al 1988;Leathwick et al 1988;Reif& Allen 1988;Duncan et al 1990;Norton & Leathwick 1990;Stewart et al 1993). However, in contrast to our results from Waipoua, in all studies (except two over small altitudinal ranges), altitude was the most important variable influencing species composition.…”

“…However, in contrast to our results from Waipoua, in all studies (except two over small altitudinal ranges), altitude was the most important variable influencing species composition. The second axis of the ordination was usually related to differences in soil properties, which were either tied to differences in soil development on different topographic units or landforms, as for DCA1 at Waipoua, or reflected soil rejuvenation occurring in dynamic landscapes through episodes of mass movement or windthrow (DeVelice et al 1988;Reif& Allen 1988;Stewart et al 1993).…”

Gradient analysis of forest vegetation in the Maungataniwha Range, western Northland, New Zealand

“…A further environmental factor that may affect species distributions in the Maungataniwha Range is variation in soil fertility./ks has been suggested by DeVelice et al (1988), soil fertility on a given parent material may vary with landtorm and soil disturbance. For example, flat terraces may be more highly leached of soil nutrients than slope,'; where recent mass soil movement has exposed relatively unweathered and nutrient-rich substrates.…”

“…An earlier study by DeVelice et al (1988) suggested the benefits of applying gradient analysis methods towards evaluating the representativeness of nature reserves in the Paparoa Range, New Zealand. The Paparoa study demonstrated the suitability of gradient analysis in an area charac terised by sharply defined vegetation/environmental patterns.…”

Using classification assignment rules to assess land-use change impacts on forest biodiversity at local-to-national scales

“…Ecosystem representation, in combination with criteria to satisfy the other goals, such as distributions of threatened species, is a key component of prioritising sites for conservation (Austin and Margules 1986;DeVelice et al 1988;Scott et al 1993). Such representation can also provide the context for assessing the biodiversity impacts of a land-use change that will irrevocably alter natural ecosystems (Noss 1990;Crist et al 2000;Monavari and Momen Bellah Fard 2010), a problem to which it is less commonly applied in the scientific literature.…”