Simulating New Zealand Forest Dynamics With a Generalized Temperate Forest Gap Model

Abstract

A generalized computer model of forest growth and nutrient dynamics (LINKAGES) was adapted for the temperate evergreen forests of New Zealand. Systematic differences in species characteristics between eastern North American species and their New Zealand counterparts prevented the initial version of the model from running acceptably with New Zealand species. Several equations were identified as responsible, and those modeling available light were extended to give more robust formulations. The resulting model (LINKNZ) was evaluated by comparing site simulations against independent field measurements of stand sequences and across temperature and moisture gradients. It successfully simulated gap dynamics and forest succession for a range of temperate forest ecosystems in New Zealand, while retaining its utility for the forests of eastern North America. These simulations provided insight into New Zealand conifer–hardwood and beech species forest succession. The adequacy of the ecological processes, such as soil moisture balance, decomposition rates, and nutrient cycling, embodied in a forest simulation model was tested by applying it to New Zealand forest ecosystems. This gave support to the model’s underlying hypothesis, derived from LINKAGES, that interactions among demographic, microbial, and geological processes can explain much of the observed variation in ecosystem carbon and nitrogen storage and cycling. The addition of a disturbance option to the model supported the hypothesis that large‐scale disturbance significantly affects New Zealand forest dynamics.

Modelling the time course of shade, temperature, and wood recovery in streams with riparian forest restoration

“…liNkNZ predictions of species replacement, species biomass, density, and basal area at New Zealand forest sites corresponded well with field measurements (Hall & Hollinger 2000;Hall 2001), and its reconstruction of potential forest cover over New Zealand matched species data from forest plots and pre-deforestation pollen samples (Hall & McGlone 2006). liNkNZ simulations for a southeastern area of the South island were statistically similar to distinct past forest types (identified from pollen data) that grew in response to subtle variations in climate and environment (Hall & McGlone 2001).…”

“…propagules from 76 tree species and 4 common tree-fern species considered fundamental to the structure and functioning of New Zealand native podocarp-hardwood forests, were assumed to be constantly available to the model throughout the simulation period (Hinds & Reid 1957;Wardle 1984Wardle , 1991Hall & Hollinger 2000). The species selected included several common early-succession and under-storey species, as well as most main canopy species found throughout New Zealand forests.…”

“…4 above-ground biomass of riparian forest at a hypothetical Waihaha forest site (c. 450 m elevation), simulated by the forest gap model, liNkNZ (Hall & Hollinger 2000), for three riparian management scenarios: A, native regeneration; B, pine (Pinus radiata) reversion; and C, active native tree planting.…”

Afforestation/reforestation of New Zealand marginal pasture lands by indigenous shrublands: the potential for Kyoto forest sinks

“…Furthermore, reversion of marginal pastoral hill-country to mānuka/kānuka shrubland meets a range of additional objectives in sustainable environmental management: creation of indigenous biodiversity, erosion mitigation and soil conservation, consequent improvements in water quality, and creation of environmentally benign revenue from honey, nutriceutical, and pharmaceutical industries [45]. Importantly, from a C sink perspective, in many areas indigenous shrubland provides the first step in a successional pathway to a permanent cover of indigenous tall forest (e.g., [1,14,32,49]). Because of NZ's temperate climate, fire seldom interferes with this succession.…”

“…Because of NZ's temperate climate, fire seldom interferes with this succession. The resultant forests typically comprise long-lived species that can achieve large stature, with diameters of 1-2 m and an active growth phase that extends from 150 to 500 years (e.g., [13][14][15]18]). Active net C accumulation over such time frames is consistent with the prolonged effort likely required to effect significant reductions in atmospheric CO 2 levels [17,38].…”