Economic feasibility of irrigating southern pines

Abstract

A climatic model developed for estimating the depressing effect of drought on the diameter growth of loblolly pines in the southern United States is used to project potential pine growth under conditions of no soil moisture deficit, which irriga.tion could assure. The regional distribution of the additional growth demonstrates that the benefits of irrigation would increase from the Atlantic coast. toward east Texas. The dollar value of the additional growth ba.sed on the current price of pulpwood is compared with the costs necessary to irriga.te southern pines. Under present conditions of technology, costs of irrigation would exceed benefits. Technological changes, higher pulpwood prices, or decisions of the federal government. to improve southern forests may justify the irrigation costs necessary to increase southern pine production. The forest resources of the southern UnitedStates produce more than 63% of the nation's pulpwood and 17% of the nation's plywood [Nelson, 1967]. A 50% increase in the southern pine lumber production is expected as a result of the urgent need for the construction of 26 million houses during the, next 8 years [Wheeler, 1969]. Apparently, the South's future role as • supplier of forest products must be even greater than the present. Field experiments to increase the production of pines beyond the present level have had limited applications to large areas in the South. Many of the studies relating to. the role of irrigation in forestry have failed to indicate how much more growth can be expected on regional basis if adequate water is made available to trees during the growing season. In fact, great loss of wood production in the South is largely attributed to the prevalence of soil moisture deficits. No effective methods have evolved to irrigate forests in the South, largely owing to the lack of adequate knowledge pertaining to the growth-depressing effect of drought and the economic feasibility of irrigating forests.The purpose of this paper is to. develop tree growth-climate model to estimate the pressing effect of drought on tree growth. This model, which predicts actual growth under specific conditions of soil moisture limitations, is used to estimate potential growth under adequate soil moisture conditions, which irrigation could assure. Additional growth, which is the difference between actual growth and potential growth, is considered as the quantity that would accrue from the use of irrigation in forestry.The current market price of wood is used to convert the additional wood produced by the use of irrigation in forestry into dollar value.The economic considerations of the value of this benefit of irrigation are compared with the costs of irrigation to test whether irrigation is economically feasible in the forest regions of the South. DATA UsEr To GE•}•AT• A Pn•v•cT•w MorELDiameter increments recorded during 1960 and 1961 on naturally occurring loblolly pines by Basserr [1964] and Moehring [1965] in southern Arkansas and northeastern Louisiana, respectively, are used to devel...

Long term growth responses of loblolly pine to optimal nutrient and water resource availability

“…The 1200 mm per year of precipitation at our site was well distributed so that the lowest average monthly precipitation was 60 mm per month in May. The evaporative demand (vapor pressure deficit) may be relatively low due to fairly high humidity levels observed during the growing season (Manogaran, 1973). Lastly, Ewers et al (1999) found that fertilization improved water use efficiency-allowing growth to continue in the fertilized stands even though water availability may have been low.…”

Water Balance Delineates the Soil Layer in Which Moisture Affects Canopy Conductance

“…Pinus taeda is particularly sensitive to drought (Stransky and Wilson 1964). Thus, in the southeastern United States, soil moisture commonly limits the growth of P. taeda, one of the most widely naturally distributed and planted tree species (Coile 1936, Bassett 1964, Moehring and Ralston 1967, Manogaran 1973, Kramer 1983). However, based on the results from this study, water stress may develop in P. taeda even where soil moisture is high not far from the surface (Fig.…”

Modelling growth of Pinus taeda and Eucalyptus grandis as a function of light sums modified by air temperature, vapour pressure deficit, and water balance

“…The sensitivity of P. taeda to VPD, soil water content, and photosynthetically active radiation was verified by Ford et al (2004). The sensitivity to the first two factors was indicated by Manogaran (1973) and confirmed in Uruguay by Gándara et al (2014). For E. grandis hybrids, soil water content and atmospheric humidity was shown to be the most important growth modifiers in Brazil (Almeida et al 2007;Stape et al 2008Stape et al , 2010.…”