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Item An integrative approach to silvopastoral system design: perspectives, potentials and principles(Informa UK Limited, trading as Taylor & Francis Group, 2024-01-01) Mackay-Smith TH; Spiekermann RI; Richards DR; Harcourt N; Burkitt LLSilvopastoral systems have complex impacts on a diverse range of outcomes, making it essential to design these systems using an integrative approach to maximise positive impacts to farms. This paper comprises firstly a systematic review of global silvopastoral processes, and secondly stakeholder-driven synthesis of key opportunities and challenges for future silvopastoralism situated in the context of New Zealand. The systematic review demonstrated that although under-researched, livestock interactions can have overriding influences on the system, and that the traditional functional traits that are typically deemed important for selection (N2-fixing trees v non N2-fixing trees, evergreen v deciduous) do not show consistent positive impacts on the agroecological environment. From the New Zealand silvopastoral participatory case study, including the stakeholder workshop, we synthesised 5 key principles that should be considered in future system designs. These were: (1) silvopastoral systems are complex and require holistic management; (2) the views, values and experiences of local people are deeply connected to silvopastoral system design; (3) spatial heterogeneity in environmental and social conditions requires locally specific decisions; (4) understanding of ecological processes must underpin all management decisions; and (5) the complexity and spatial heterogeneity present in silvopastoral systems requires high-resolution data and tools.Item Implications of tree management on poplar and willow pasture-tree systems : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Plant Science, Massey University, Palmerston North, New Zealand(Massey University, 2016) Maldonado Garcia, Noel MauricioWillow and poplar trees planted at wide spacing have proved their effectiveness as a biological method to control soil erosion in pastoral hill country. Due to lack of management, many trees aged 30+ years have grown very large (>60 cm diameter at breast height), resulting in excessive shading of understorey pasture. The large trees are also prone to breakage of branches and toppling during strong winds, potentially damaging farm infrastructure or injuring livestock. Management of tree size can coincide with providing edible poplar and willow foliage as a source of supplementary fodder in summer droughts. Trees can be pollarded, involving total canopy removal, but the effects of pollarding on tree root dynamics are poorly understood. This thesis evaluated the effect of the tree canopy removal on the root dynamics and root non-structural carbohydrate dynamics of pollarded mature willow and poplar trees and decapitated young willow and poplar trees grown from cuttings. Impacts of tree canopy removal when trees were at different phenological stages were also studied in pollarded mature willow trees and decapitated young willow and poplar trees. Finally, herbage accumulation under pollarded trees was contrasted with herbage accumulated under unpollarded (UP) trees and in open pasture sites (OP) away from direct tree influence. Pollarding did not impose a unique impact on the root structure of mature willow and poplar trees. However some similarities were found in both species. For instance, pollarding had its main impact in the roots closest to the trunk and above 300 mm soil depth. In these root sections disrupted by pollarding, fine root length and mass of pollarded (P) trees were, one year after above-ground removal, from 2× to 4× less than equivalent unpollarded (UP) trees. However, one year after pollarding, pollarded trees recovered or maintained the initial fine root densities recorded in the same trees prior to pollarding. The study conducted with young willow and poplar trees grown from cuttings showed that willow trees had a greater ability to recover from damage in the root structure after decapitation. Nine months after decapitation in early autumn, root mass of young willow decapitated trees was 57% greater than prior to decapitation and 64% less than non-decapitated (ND) trees. In contrast, within the same time frame, root mass of young poplar trees decapitated in early autumn was 80% less than ND trees and 52% less than the initial root mass recorded prior to decapitation. Greater resprouting ability of willow trees than poplar trees after decapitation was proposed as the cause for the greater resilience to decapitation observed in willow trees than in poplar ones. Further evidence for a greater resilience to pollarding of willow trees was found in the root starch dynamics evaluated after tree canopy removal. Pollarded or decapitated willow trees (mature or grown from cuttings) were able to replenish their root starch concentrations similarly to UP or ND trees in the growing season following tree canopy removal. In contrast, both pollarded and decapitated poplar trees (mature or grown from cuttings) had lesser root starch concentrations than intact trees one year after tree canopy removal. Pollarding (P) or decapitation (D) at dormancy (DP or DD trees) showed no clear advantages in terms of the tree root structure maintenance or recovery after above-ground removal, over pollarding or decapitating the trees towards the end of the growing season in early autumn (AP or AD trees), when trees still had leaves. With mature willow trees, annual average fine root density (fRD) recovery of DP trees relative to pre-pollarding density was greater than annual average fRD recovery of AP trees. However, this difference was attributed to record moisture restrictions that disrupted the root growth of both AP and UP trees during the growing season following early autumn pollarding. Similarly, young DD and AD willow and poplar trees showed that four and a half months after decapitation, both treatment trees were able to recover or maintain initial root mass recorded prior to decapitation. The study on herbage accumulation beneath pollarded trees, suggests that 4 years after being pollarded, P willow trees shaded pasture in a similar way to UP trees, as annual net herbage accumulation (NHA) attained in these two environments was statistically not different. Annual NHA under P and UP environments, were, respectively, 30 and 43% less than annual net herbage accumulation recorded in open pasture sites (4.9 t DM ha-1 yr -1). Ability of willow trees to recover, within the first year after pollarding or decapitation, initial root densities recorded prior to canopy removal, and to replenish root starch concentration similar to intact trees, suggests these trees could have pollarding cycles of 2 to 3 years. Short pollarding cycles could lessen herbage accumulation reductions on a pasture-tree stand level as more trees or more frequent repollarding is practised. However, results derived in this thesis from willow trees, need to be confirmed in at least two year lasting studies before recommending shorter pollarding cycles than currently advised of 3 or 4 years. In contrast, poplar trees require longer pollarding cycles or higher tree stand densities if a pollarding program is instituted, as these trees were not able to recover within the first year after canopy removal, the root values recorded prior to pollarding and/or to replenish the root starch reserves.Item Diversification of Wairarapa hill country : the potential for agroforestry : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science at Massey University(Massey University, 1987) Spall, James GordonThe purpose of this study was to investigate the potential for agroforestry on Wairarapa Hill Country farms. It was set against a background of a marked decline in real farm income on hill country sheep and beef farms in recent years. A broad perspective on project evaluation was taken with a review of the system components presented; covering hill country farming in New Zealand, the Wairarapa, Forestry in New Zealand, and Agroforestry. The results of an intertemporal linear programming model covering a 21 year period, suggest that agroforestry can be both a profitable and feasible investment for Wairarapa Hill Country farmers. Profitability is shown to be strongly influenced by the suitability of planting sites and final timber value. With respect to feasibility, cash-flow considerations are of overriding importance. Together with factors considered outside the model, particularly the management of an integrated livestock and agroforestry property, the need for individual evaluation of each circumstance is stressed. It is recommended that significant development of agroforestry in the Wairarapa will require some form of District Association to co-ordinate planting and marketing, and provide suitable extension and management services. Further development of the model for both agroforestry and land use evaluation is suggested.Item Sustainability of agroforestry in New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Master of Philosophy in Regional Planning at Massey University(Massey University, 1995) Bray, Tania LThe aim of this thesis is to assess the concept of sustainability and apply it in a practical sense to New Zealand agroforestry. Sustainable management of natural resources is fast becoming recognised as necessary for the long term survival of our species. The agricultural communities prominence as the major user and steward of New Zealand's natural resources requires change in the values placed on these resources by farmers, and the incorporation of the principle of sustainable management at the farm level. The concept of sustainability is broken into three component parts; economic, environmental and social sustainability. Each of these components is broken again into specific measurable principles. Through literature research and a case study, the principles are applied to agroforestry, and a conclusion reached. It is found that given good management practices and normal business risks, agroforestry had the potential to maintain the natural capital stock and remain relatively profitable. Agroforestry is also found to have the potential to maintain the life support systems and biodiversity of the environment. Finally agroforestry is found to positively impact on rural societies, and provide the necessities of life and is relatively robust to political change. This thesis concluded that agroforestry as practiced in New Zealand is a profitable enterprise which improves the environment and increases the viability of many rural communities.Item Growth of pasture species in the shade in relation to alder silvo-pastoral systems : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy (Ph.D.) in Pastoral Science, Institute of Natural Resources at Massey University, New Zealand(Massey University, 2000) Devkota, Naba RajAn increased understanding of the competitive interactions between tree species and understorey pastures is required for the development of deciduous tree based silvo-pastoral systems. In particular, the shade tolerance of pasture species likely to be used under trees in New Zealand needs to be determined. This thesis examines the effects of light intensity and quality on the growth of pasture species in a series of glasshouse experiments, and under the shade of alder trees pruned to different heights. The shoot dry weight per plant of all grass and legume species examined showed a linear increase (P<0.0001) with % ambient photosynthetically active radiation (PAR). Highest shoot dry weight was at 73% and lowest was at 14% PAR (heavy shade). Shade also affected the tillering ability of pasture species. Under heavy shade, cocksfoot (Dactylis glomerata L.) produced more tillers per plant than the other grass species examined. Perennial ryegrass (Lolium perenne L.) had the lowest tillering in heavy shade. Under medium shade (43% ambient PAR), tiller number per plant for browntop (Agrostis capillaris L.) and Poa trivialis (Poa trivialis L.) was higher than other species. Lotus (Lotus uliginosus L.) produced a higher (P<0.0001) number of branches under heavy shade than white clover (Trifolium repens L.) and subterranean clover (Trifolium subterraneum L.) Shade affected perennial ryegrass more than cocksfoot selections, especially at the lowest PAR level both in the glasshouse and the field experiment. For example, tillers per plant under tree shade, and also at the low PAR level in the glasshouse for perennial ryegrass were 18 compared with 28-29 (P<0.0001) for Wana cocksfoot and 24-27 for PG 74 cocksfoot. Leaf area per plant for perennial ryegrass was also significantly (P<0.0001) lower than for Wana cocksfoot. Cocksfoot selections were more tolerant of heavy shade than perennial ryegrass, and Wana was the most tolerant of the cocksfoot selections of heavy shade. There were no effects of R:FR ratio (P>0.05) on the shoot dry weight production of the pasture species examined. Similarly, the interaction between PAR x R:FR and species was not significant (P>0.05) for most morphological characteristics when plants were not defoliated. Perennial ryegrass, Wana cocksfoot and Yorkshire fog (Holcus lanatus L.) at low PAR had similar yields, that higher than white clover and lotus, which were similar. However, when plants were defoliated weekly or three-weekly, Wana cocksfoot out produced Nui perennial ryegrass at low PAR/R:FR due to its ability to maintain higher leaf area and higher leaf dry weight, higher SLA, and more tillers per plant. Herbage mass of swards in heavy and medium shade created by pruning alder trees was about 50% and 70%, respectively, of that of light shade (P<0.0001). Herbage mass was highest for cocksfoot either with lotus or white clover (P<0.0001), whereas values for perennial ryegrass and Yorkshire fog were lower and similar. Shade affected perennial ryegrass more than cocksfoot and Yorkshire fog, especially at the lowest PAR level. Cocksfoot in mixture with either white clover or lotus had the highest leaf expansion per tiller, which was in the order cocksfoot> Yorkshire fog>perennial ryegrass. There was no significant difference (P>0.05) between the pasture species in the total number of sheep grazing observations in 2 hours, but more sheep grazed in light shade than in heavy shade (P<0.05). The research highlighted the importance of measuring shade tolerance of pasture species in terms of attributes that determined growth and persistence. As perennial pasture species are regularly defoliated they must be able to vegetatively reproduce in the shade as well as be productive. Shade tolerance of the pasture species examined varied greatly, but their relative shade tolerance was also sensitive to the level of shade. Although, cocksfoot was the most shade tolerant species in heavy shade (PAR level <200 μmoles photons m-2 s-1) it was similar to other species in medium shade (PAR level ≥ 400 μmoles photons m-2 s-1 or more). Light intensity was more important for growth and vegetative reproduction than light quality for pasture species under shade. Likewise, pruning trees was more important for pasture production under tree shade. The morphological attributes related to shade tolerance of New Zealand hill country pastoral plants were identified in this thesis as tiller number per plant, leaf area, specific leaf area (SLA), and leaf appearance interval. For alder silvo-pastoral systems with high tree density and heavy shade (PAR level <200 μmoles photons m-2 s-1) cocksfoot in combination with either lotus or white clover was the most productive pasture, while perennial ryegrass, or browntop, with white clover was as productive as cocksfoot if shade was maintained at a PAR level >200 μmoles photons m-2 s-1). Additionally, cocksfoot and lotus are both tolerant of the low to medium soil fertility and seasonal dry periods likely to be encountered on the hill country where deciduous trees are also used to control soil erosion. Shade had a marked effect on tillering as well as on shoot dry weight, and is the most significant factor determining the understorey pasture production. However, the decrease in pasture production due to shading can be managed by appropriate pruning practices and choice of appropriate pasture species.Item Aspects of a poplar-pasture system related to pasture production in New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Plant Science at Massey University, New Zealand(Massey University, 1999) Guevara-Escobar, AurelioWidely spaced poplars (Populus deltoides, <100 stems/ha) are the best technology to control soil erosion over 3.7 x 10 6 ha in New Zealand on sedimentary hill soils. To date, the effects of poplars on water, soil and pasture relations are poorly studied. This thesis compared traditional stable open pasture (OP) and widely spaced poplars (5-40 years old) and its grass/legume un-derstorey (PP) based on rainfall partitioning, soil and pasture characteristics. It was concluded that mature PP (>29 years old and 37-40 stems/ha) used more water during November (18 days) as evapotranspiration (ET, 2.7-3.0 mm d-1) than the OP (2.2 mm d-1). Canopy rainfall interception (1.37 mm d-1) was more important than tree transpiration (0.92 mm d-1) or understorey ET (0.4-0.6 mm d-1). Despite the differences in water partitioning, soil water (θ) in the PP was similar or higher than in the OP. The mature PP had lower topsoil θ (0-150 mm) than the OP during 1996 (37 and 43 %v/v, respectively). PP topsoil was drier in January, May and June, but θ was similar to the OP in other months of 1996. During dry weather (1997), θ in the topsoil was higher in the PP than in the OP. Variation in θ around the trees was significant but small in magnitude. PP soil temperature was lower than in OP particularly during summer. Soil pH was higher (0.5-1.2 units) in the PP as were exchangeable cations. Poplar leaf litter decomposition along with poplar N nutrition, reduced soil water leaching and legume N-fixation, all contributed to higher soil pH. Using the legume dry matter (DM) as a proxy of N-fixation, the PP fixed 54% of that in the OP. With the exception of lower total N in the PP, little differences were found in organic C, total N, P or S, or soil P or S fertility, hydraulic conductivity, porosity and water aggregate stability between the OP and PP. Earthworm populations were similar or lower in the PP. Pasture DM accumulation in the mature PP was 60% (6.2 t ha-1 yr-1) of that in OP as the poplar canopy (70% canopy closure ratio) allowed only 20% of the photosynthetically active radiation in the OP to reach the understorey. The legume proportion was similar between the OP and PP, although actual yield was lower in the PP. The PP area had slightly lower grass percentage at the expense of higher comminuted tree debris material. OP forage generally had higher feed value in terms of crude protein, metabolisable energy and in vitro DM digestibility. With the exception of higher soil pH, no difference in other soil or understorey characteristics was found between the OP and PP planted with young poplars. The understorey could take advantage of improved soil water and pH conditions if silvicultural management reduced the shading effect from poplars without impairing soil conservation. Canopy and understorey management options to increase/better utilise pasture DM are discussed.Item Environmental effects of densely planted willow and poplar in a silvopastoral system : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy (Ph. D.) in Agroforestry, Institute of Natural Resources, Massey University, Palmerston North, New Zealand(Massey University, 2007) Hussain, ZakerNew Zealand, having large areas of hilly landscapes, is subject to the risk of soil erosion, and summer and autumn droughts that limit pasture growth, which in turn affects the livestock-based economy. The nitrogen and phosphorus input in fertilisers coupled with livestock excreta and soil disturbance impose a serious threat to downstream water quality. The planting of trees is one option used to decrease soil erosion, increase the quantity of forage and manage runoff. To date, research has mainly focused on wide spaced poplar trees for feed quality and their effects on understorey pasture growth. However, there is increasing interest in the use of densely planted willow and poplar for fodder purpose. The effects of young (< 5 yrs old) willow and poplar planted at close spacing on runoff, soil erosion, growth of understory pasture and nutrient losses have never been studied in New Zealand. Three field trials (two at Crop and Research Unit, Moginie, Manawatu and one at Riverside Farm, Masterton) were conducted between October 2004 and November 2006 that incorporated comparative establishment and growth of densely planted willow and poplar and their effects on soil moisture, runoff, sediment load and nutrient losses from grazed and fertilised farmland. It was concluded that densely planted willow and poplar (3-4 yrs) reduced total nitrogen (TN) and dissolved reactive phosphorus (DRP) by 47 % each and sediment load by 52 %. Young trees reduced surface runoff and soil moisture more as they aged. However, due to their deciduous nature willow and poplar were not effective in reducing surface runoff in winter and early spring. Sheep preferred camping under trees, especially in late spring and summer, and this led to greater deposition of dung and urine under trees than open pasture. Sheep grazing, especially in winter, significantly increased sediment and nutrient loads in runoff water. The N and P fertiliser application increased nutrient load in runoff water well above the threshold level required to initiate algal growth to create eutrophication. Densely planted willow and poplar significantly reduced understorey pasture growth by 23 % and 9 %, respectively, in their second year at Moginie, mainly due to shade, but coupled with soil moisture deficit in summer. The pasture growth in a willow browse block was 52 % of that in open pasture as a result of shade and differences in pasture species composition. Sheep browsing reduced willow leaf area significantly. Willow and poplar survival rates were similar (P > 0.05) after two years of establishment (100 % vs 90.5 %, respectively). However, willow grew faster than poplar in height (1.90 vs 1.35 m), stem diameter (43.5 vs 32.6 mm), canopy diameter (69 vs 34 cm) and number of shoots (8.7 vs 2.3) at the age of two years, respectively. The research clearly demonstrated that densely planted young willow and poplar trees can reduce runoff, sediment load and nutrient losses from farmland to freshwater, but shade and soil moisture can limit pasture growth under trees. It is recommended that willow and poplar should be planted at wide spacing on the whole farm to minimise loss of pasture. Where blocks of trees are necessary, such as willow browse blocks, sheep browsing can be used as a tool to reduce shade to improve pasture growth. Livestock access to riparian strips should be minimal to avoid livestock camping that can have deleterious effects on water quality.