Utilization of non-timber forest products in humid tropics: Implications for management and livelihood

Community dependence on forest resources for diverse needs has high implications for long term management of forests. Sustainable extraction of non-timber forest products (NTFPs) is considered best feasible strategy for forest conservation in biodiversity rich areas. This paper examines the heterogeneity of NTFPs use by tribal communities in northeast India, a global hot spot by examining diversity of NTFPs at-large, its consumption pattern, and contribution to rural income and forest revenue. A total of 343 NTFPs recorded used for diverse purposes by tribal communities. When species choice grouped as per use category, utilization for medicinal (163 species), edible fruits (75 species) and vegetables (65 species) purposes was reasonably high. Community dependence on forest resources was 100% for firewood and house construction material. 76 plant species were sold in three major local markets while an additional 22 species traded at commercial scale mainly outside the state. NTFPs contributed 19-32% of total household income for different tribal communities, which was significant. Illicium griffithii, Rubia cordifolia, Oroxylum indicum, Swertia chirayita, Litsea sebifera, Taxus wallichiana, Valeriana jatamansii, Thalictrum foliolosum, Picrorhiza kurrooa, Everniastrum cirrhatum, Cordyceps sinensis, Aconitum fletcherianum, Nardostachys jatamansi, Picrorhiza kurrooa, Gymnadenia orchidis, Calamus, Quercus and Pinus roxbughii were important commercial species. NTFPs also generated substantial revenue to the State government, though it is falling year after year, which is alarming. To meet community livelihoods, income and forest revenue from NTFPs, it desires a thorough management plan and policy guidelines for these resources from all line departments. The knowledge on diversity, its consumption pattern, and contribution to rural income and forest revenue may enable planners to accurately plan sustainable management of NTFP resources and community development in near future.     

The ecology and management of the Miombo woodlands for sustainable livelihoods in southern Africa: the case for non-timber forest products

There is new and increasing emphasis on the contribution of non-timber forest products (NTFPs) to improving the livelihoods of rural communities and therefore the need for sustainable management of forest ecosystems of the Miombo woodlands to ensure the continued availability of these NTFPs. This paper examines and reviews some of the work that has been done in the Miombo ecoregion on the ecology, utilisation and management of the Miombo woodlands. The review points to the richness of the Miombo regions' plant species, with an estimated 8 500 species of higher plants, of which over 54% are endemic. The review also highlights the response of the Miombo ecosystem to fire and other anthropogenic processes and the lack of wide-scale adoption or implementation of the major research findings. The review shows that there is a wide range of NTFPs that significantly contribute to the total household income in forest areas and to the national economies through provision of opportunities for small-scale trade especially in the rural areas. However, there is a concern that commercialisation usually results in overexploitation of the resource by the outsiders who become the major players. It is suggested from the review that the lack of capacity by national institutions to manage Miombo woodland resources could be addressed by using participatory approaches to natural resource management. It is also proposed that for sustainable use and management of NTFPs in the Miombo region, research should focus on issues that specifically address NTFPs. In order to facilitate commercialisation and benefit the economically weak, policies that incorporate postharvesting technical assistance and access to information on markets, technology and microcredit should be developed and promoted.     

Invasive alien trees and water resources in South Africa: case studies of the costs and benefits of management

Invasive alien plants are consumptive water-users, and may have reduced river flows in South Africa by about 6.7% according to a broad-scale study. An effective programme to bring the invasions under control would cost about US$ 92 million per year for the next 20 years. This paper reports on studies of four representative catchments (the Sonderend, Keurbooms, Upper Wilge and Sabie-Sand) to assess the impacts and costs of invasions at a scale that is more relevant to managers. Several alien plant species have invaded the catchments. Non-riverine invasions are mainly Pinus and Hakea species in Sonderend and Keurbooms, eucalypts in the Upper Wilge, and pines and scramblers (e.g. Lantana camara) in the Sabie-Sand catchment. Riverine invasions are dominated by Acacia mearnsii and, to a lesser extent, A. dealbata, except in the Sabie-Sand and the lower Sonderend River where Eucalyptus species are important. About 44% of the Sonderend, 54% of the Keurbooms, 2% of the Upper Wilge and 23% of the Sabie-Sand catchments has been invaded to some degree. The corresponding reductions in the natural river flows attributed to these invasions are about 7.2, 22.1, 6.0 and 9.4%. If the invasions are not controlled they could potentially spread, and occupy 51, 77, 70%, respectively, of the first three catchments. At an annual expansion rate of 10–15% this would take about 13, 26 and 63 years, respectively. The invadable areas in the Sabie-Sand catchment are already invaded so invasions will only increase in density. It would take about 26–30 years to reach 100% canopy cover. The projected flow reductions for the four catchments would increase to 41.5, 95.5, 25.1 and 22.3%, respectively. The estimated cost of the control programmes to prevent these losses would be about US$ 13.2, 9.9, 4.1 and 6.6 million for the Sonderend, Keurbooms, Upper Wilge and Sabie-Sand catchments, respectively. Should the catchments be allowed to become fully invaded before control operations were started, then the costs would rise to US$ 86.5, 20.5, 278.0 and 11.1 million, respectively. The impacts and costs are significant and are comparable with those calculated independently for other South African catchments. Water is acknowledged to be a key constraint to economic growth in South Africa and there is considerable pressure for efficient and sustainable use of the limited water resources. The projected impacts would justify control programmes aimed at clearing alien invaders for water conservation.     

Genetic variation for carbon isotope composition in honey mesquite (Prosopis glandulosa)

Carbon isotope composition (delta(13)C) is a useful surrogate for integrated, plant water-use efficiency (WUE) when measured on plants grown in a common environment. In a variety of species, genetic variation in delta(13)C has been linked to the distribution of genotypes across gradients in atmospheric and soil water. We examined genetic variation for delta(13)C in seedlings of honey mesquite (Prosopis glandulosa Torr.), an invasive grassland shrub that thrives in the southwestern USA. Fifteen maternal families, representing progeny of 15 adult trees, were studied in three common garden experiments in a greenhouse. The 990-km east-west transect along which the adult trees were located encompasses a wide precipitation gradient, and includes mesic grassland, semiarid grassland, and Chihuahuan desert ecosystems. Genetic variation for delta(13)C in mesquite was substantial, with the rank order of half-sib families based on delta(13)C relatively stable across experiments, which were conducted under different environmental conditions. Conversely, rankings of families by mean seedling height (an index of growth rate) varied markedly among experiments. Seedlings derived from Chihuahuan desert adults emerged more quickly and had more negative delta(13)C (indicative of lower WUE) than seedlings derived from the other regions. Although delta(13)C and seedling height were not correlated, these results suggest that mesquite genotypes at the drier, western extreme of the species' range are adapted for quicker emergence and possibly faster growth than genotypes from mesic areas. Together, these traits may facilitate exploitation of infrequent precipitation events.     

Demand for non-timber forest products: Surveys of urban consumers and sellers in Switzerland

In recent years, worldwide socioeconomic, ecological, and cultural changes have led to a paradigm shift in forestry and forest management. Some years ago, most forest enterprises exclusively focused on wood production, whereas today, forest management is expected to be multifunctional and economically as well as socially and ecologically sustainable [Harrison, S., Herbohn, J., Niskanen, A., 2002. Non-industrial, smallholder, small-scale and family forestry: what's in a name? Small-scale Forest Economics. Management and Policy 1 (1), 1–11; Schmithuesen, F., 2004. Forest policy developments in changing societies — political trends and challenges to research. Towards the sustainable use of Europe's forests: Forest ecosystems and landscape research: Joensuu: European Forest Institute, Proc., vol. 49, pp. 87–99]. In this context, non-timber forest products (NTFPs) such as forest honey, mushrooms, or berries could gain importance as an additional source of income for the forestry sector. To assess the market potential of NTFPs in Switzerland, two corresponding surveys were conducted. A consumer survey (N = 897) conducted in six cities in Switzerland investigated the purchase of Swiss NTFPs, consumer preferences, and demand potentials. An additional survey of sellers of NTFPs (N = 105) looked at these aspects from a complementary perspective. The results showed that there is a high esteem and considerable demand potential for such products among urban consumers. Food products were mentioned most frequently. Both consumers and sellers considered quality and environmental friendliness the most important attributes of NTFPs. Structural and organizational innovations and considerable marketing efforts and sales promotion would be required to expand the market for Swiss NTFP, however. Our results indicate that certification of the products' origin, environmental performance, and quality could support such efforts and that recreational and ecological forest services have a synergetic potential for the marketing of NTFPs.     

Antecedents to forest owner innovativeness: An investigation of the non-timber forest products and services sector

Increased urbanization in many societies is having a negative impact on vitality of rural areas. To maintain the vitality of these areas governments have employed a variety of policies, some of which are designed to facilitate innovation and enhance landowner innovativeness. However, little research has investigated the antecedents to landowner innovativeness and whether innovativeness positively impacts economic performance in this setting. The present study investigates these issues in the context of Norwegian forestland owners and their involvement in non-timber forest products and services (a form of ecosystem services). The authors present a conceptual model hypothesizing that social networking, entrepreneurial climate, and a learning orientation each have a direct, positive impact on landowner innovativeness and innovativeness has a direct, positive impact on economic performance. Property size is included as a moderating variable. Data were collected via a mail survey and a total of 683 useable responses were received reaching an adjusted response rate of 35%. Results show that social networking and a learning orientation positively impact innovativeness, but that entrepreneurial climate does not. Innovativeness was found to positively impact economic performance. The authors outline implications of the findings that may be used by policy makers, landowners and research.     

Quantitative and financial evaluation of non-timber forest products (case study: Zemkan basin forests,West of Iran)

Although Zagros forests in western Iran lack industrial timber value due to the severe climate and socioeconomics problems, non-timber products are of great value and importance due to their high economic potential and also their potential to improve the welfare of forest-dwelling and forest-fringe villagers. This study was done in the forests of the Zemkan basin, an important part of central Zagros forests, Iran, to recognize the non-timber forest products (NTFP_S), investigate their potential economic value and role in people’s livelihood. Data, collected using forest cruising, participatory observations, interviews with indigenous and local persons and experts, identified wild pistachio resin, wild pistachio fruit, oak fruit and oak syrup (Shokeh manna) among the non-timber products in this basin with total potential harvestable NTFPs of 77.16, 771.602, 13248.68, and 1324.868 tons per year, respectively. The economic rent from NTFPs is 33 US$/ha/year and its total expected values with consideration of real interest rate when the exploiter invests the capital in the bank (6.4 %) and when money is borrowed from the bank to execute the incorporated projects (8.4 %) are $516/ha and $393/ha, respectively. Furthermore, families’ economic share from potential profit of NTFPs is annually $601 per household. In addition wild pistachio resin has the highest share of the total potential profit of NTFPs and its equal to 51 % of the total of potential profit of NTFPs. Therefore, it is suggested that decisions be made to increase the infrastructure and strengthen the local selling market to enhance the cash income from NTFPs. Forest participatory management practices are suggested to organize and improve traditional use of the forests.     

Evaluation of potential gross income from non-timber products in a model riparian forest for the Chesapeake Bay watershed

The creation of riparian forest buffer zones for water quality management in agricultural landscapes takes land out of production, incurring an economic loss for the landowner. However, planting and harvesting techniques, such as those employed in indigenous systems of tropical agroforestry, can enhance riparian forest buffer strips with economically viable species. This kind of riparian forest buffer can be harvested and generate income from otherwise unproductive tracts of land. This practice would make the implementation of riparian forest buffers more acceptable to farmers, by generating income while helping to improve water quality. The present project provides an economic model for the harvest of non-timber products (fruits, nuts and ornamentals) from riparian forest buffer zones in the Chesapeake Bay region. Potential gross income from harvest is calculated to demonstrate the feasibility of this strategy. Given certain assumptions, the gross income can amount to $60,934.30/ha/year. This revised version was published online in June 2006 with corrections to the Cover Date.     

Allelopathic effects of invasive Eucalyptus camaldulensis on germination and early growth of four native species in the Western Cape,South Africa

Eucalyptus camaldulensis Dehnh. (red river gum; Myrtaceae) is an invasive tree in riparian habitats of the Western Cape, South Africa, where it replaces indigenous vegetation and affects ecosystem functioning. These invasions lead to changes in river geomorphology and reduction in stream flow. The mechanisms that drive these effects are poorly understood. The potential for allelopathic effects of aqueous extracts of E. camaldulensis tissues and of soil and litter collected beneath E. camaldulensis trees on the germination and seedling growth of four selected native plant species was investigated in a greenhouse experiment. Soils collected beneath E. camaldulensis trees were used in three treatments: untreated soils, sterilised soils and sterilised soils overlaid with a eucalypt litter layer. In addition, soils collected from underneath native species were used in two treatments: untreated soils and soils overlaid with a eucalypt litter layer. All soil treatments were watered with three E. camaldulensis leaf, bark and root aqueous treatments. Compounds present in the aqueous extracts and fresh samples were identified using gas chromatography. Soil and aqueous treatments showed varying effects on germination and seedling growth of the four native species. Germination and seedling growth of Olea europaea subsp. africana and Dimorphotheca pluvialis were significantly reduced by E. camaldulensis root and bark aqueous extracts as well as by the soils treatments. The addition of eucalypt litter to native and sterilised soils reduced shoot and root growth of all four native species. Compounds such as -phellandrene, eucalyptol, p-menth-1-en-8-ol and -pinene, which have the potential to inhibit germination and plant growth, were identified in E. camaldulensis aqueous extracts and fresh samples. Although the methods applied in this study had limitations (e.g. lack of control treatment to litter addition), the results provide an additional motivation to prioritise removal of invasive E. camaldulensis stands from riparian ecosystems. Restoration initiatives should target native species that are not negatively affected by allelopathy.     

Genetic evaluation of Prosopis alba (algarrobo) in Argentina for cloning elite trees

Algarrobo (Prosopis alba) is an important nitrogen-fixing tree adapted to the semiarid regions of northwestern Argentina. The tree provides fuelwood and dimensionally stable lumber for flooring and furniture; its pods that have a high sugar content are consumed by livestock and humans. P. alba has been one of the most heavily harvested species. This paper reports on the evaluation of a nine-year-old Prosopis alba progeny trial containing 57 half-sibling families of eight provenances in northwestern Argentina (of the 1,596 trees planted, 1,289 survived in 1999). Considering the multiple uses of P. alba, the selection criteria included: total biomass production (from basal diameter using regression equations), height, rate of pod production, and pod sensory characteristics. The family-narrow-sense-heritability was 0.487 for height. 0.548 for biomass production, and 0.244 for pod production. In 1998, 12 of the 1,289 trees were more than 4 m tall and had more than 1.75 kg pods per tree; and their pods had a sweet or very sweet non-astringent taste. Scions from these 12 trees were successfully grafted onto unselected P. alba rootstock. These are currently being used to produce rooted cuttings. The pod production, biomass, and height of the 12 clones ranged from 6.55 to 14.4, 1.57 to 13.5, and 1.29 to 1.70 times the respective population means. The genetic gains of 13.5%, 77%, and 147% for height, biomass, and pod production respectively are greater than genetic gains for other tree species and are probably due to the great genetic variability in the local population and the lack of any prior genetic improvement program.This revised version was published online in November 2005 with corrections to the Cover Date.     

Population distribution and threats to sustainable management of selected non-timber forest products in tropical lowland rainforests of south western Nigeria

Uncontrolled harvesting of non-timber forest products (NTFPs) poses a serious risk of extermination to several of these species in Nigeria. Yet, there is a paucity of information on the distribution, population status and sustainable management of NTFPs in most of the tropical lowland rainforests. We, therefore, assessed the population, distribution and threats to sustainable management of NTFPs within the tropical lowland rainforests of Omo and Shasha Forest Reserves, south western Nigeria. Data were obtained through inventory surveys on five top priority species including: bush mango (Irvingia gabonensis (Aubry-Lecomte ex O’Rorke) Baill), African walnut (Tetracarpidium conophorum (Mull. Arg.) Hutch. & Dalziel syn. Plukenetia conophora), chew-stick (Massularia acuminata (G. Don) Bullock), fever bark (Annickia chlorantha Setten & P.J.Maas syn. Enantia chloranta) and bush pepper (Piper guineense Schumach. & Thonn.). Purposive and stratified random sampling techniques were used for the inventory. Each forest reserve was stratified into three, viz: less disturbed natural forest (for areas that have been rested for at least ten years), recently disturbed natural forest (for areas that have suffered one form of human perturba- tion or the other in the last five years), and plantation forest (for areas carrying forest plantation). Data were collected from eighteen 10m×500m belt transects located in the above strata. The species were gener- ally fewer in both plantation and recently disturbed natural forest than the less disturbed natural forest, suggesting that forest disturbances (habitat modification) for other uses may have an effect on the occurrence and densities of the NTFPs. Exceptions to this trend were found for P. guineense and T. conophorum, which were fairly common in both planta-tion and recently disturbed natural forest. Among three tree NTFP species (i.e. I. gabonensis, M. acuminata and A. chlorantha), only I. gabonensis showed a significant difference in overall DBH size classes for both reserves (t=-2.404; df =21; p=0.026). Three tree NTFP species in both reserves further showed differences from the regular patterns of distribution of trees. The fairly regular reverse J-shaped size class distribution observed for M. acuminata in the study sites, however, suggests a recuperating population. In general, destructive harvesting of species, logging operations, low population size, narrow distribution ranges and habitat degradation are the major threats to the population of NTFPs in the study area. The implications of our findings for sustainable management of NTFPs in the study area are discussed and recommendations are made for a feasible approach towards enhancing the status of the species.     

Photosynthesis in co-occurring invasive Acacia spp. and native Bornean heath forest trees at the post-establishment invasion stage

Seedlings of invasive species often exhibit superior physiological traits that facilitate their spread at early stages of invasion, although it is unclear whether these traits persist at the post-establishment stage. To determine whether mature exotic Acacia spp. possess superior traits over mature native plants, we compared foliar gas exchange and chlorophyll a fluorescence of Acacia auriculiformis and Acacia mangium coexisting with tropical heath forest tree species Buchanania arborescens and Dillenia suffruticosa in Brunei Darussalam. The CO₂ assimilation rates of Acacia spp. were significantly higher than those of heath species at current prevailing conditions of ~400 ppm ambient CO₂, 1,500 µmol m^?2 s^?1 photosynthetically active radiation and 30°C leaf temperature. The photosystem II of Acacia spp. exhibited significantly higher maximum quantum yield of primary photochemistry at comparable temperatures, and was more sensitive to an elevated temperature (42°C for 1 h). Better photosynthetic performance of Acacia spp., due to larger stomatal openings, better light harvesting efficiency, and greater plasticity in photosystem II, may enable adult Acacia trees to sustain a competitive growth advantage and suppress native tropical heath forest species. The competitive advantage maintained by Acacia spp. in post-establishment stage likely facilitates the establishment of monospecific Acacia stands in invaded heath forests.     

Silvicultural treatments for sapling mesquite (Prosopis glandulosa var. glandulosa) to optimize timber production and minimize seedling encroachment

To maximize lumber production and minimize weed problems with Prosopis glandulosa, silvicultural treatment methods were evaluated nine years after initiation. A randomized complete block design was used with four replicates and six treatments. Plots were shredder-harvested leaving sixteen 2-m squares on 10-m spacing that included a final rotation crop tree. In three of the treatments the crop trees were pruned to a single stem. To prevent re-establishment of mesquite in the interstitial areas, plots were spot sprayed with herbicides, disked, or disked and seeded with rye grass in 1986. Herbicide treatments and disking continued yearly through 1989. In 1991, disk treatments were repeated. After both 2.5 and 9 yrs, significant treatment differences were found for growth of basal diameter, growth of basal area, and growth of dry weight. The greatest crop tree growth occurred in treatments that were pruned with interstitial competition suppressed. Mortality was greatest in the dense treatments, while re-establishment of mesquite was greatest in the more open treatments. The greatest basal diameter growth of 1.21 cm year⁻¹ in the disked and pruned treatments is comparable to other fine hardwoods in temperate and dry tropical forests.     

Nesting chronology of northern goshawks (Accipiter gentilis) in Wales: implications for forest management

Northern Goshawks (Accipiter gentilis) in Wales built or refurbishednests between September and April in a semi-upland environment.Dates of first egg-laying ranged between late March and mid-May.There was no statistically significant annual difference inthese dates. Most young hatched in late May and juveniles hadleft their nesting territories by early August. Goshawks didnot tolerate disturbance from forestry operations during incubationand the early chick stage, and breeding failures occurred asa result of disturbance. However, once the young fledged (midJuly), forestry operations were no longer detrimental as adultsand young moved to adjacent forested areas     

Determinants of engagement in non-timber forest products (NTFPs) business activities: A study on worker households in the forest areas of Daxinganling and Xiaoxinganling Mountains,northeastern China

This study used data of 128 worker households that possessed woodland resources and owned by seven forestry bureaus (counties) belonging to the forest areas of Daxinganling and Xiaoxinganling Mountains to analyze the behavioral characteristics of worker households that engaged in non-timber forest products (NTFPs) business activities. A logistic regression model was utilized to analyze factors that influenced worker households to engage in NTFPs business activities. The study found the following: NTFPs collection activities had become the primary NTFPs business activity engaged in by the worker households in the forest areas of Daxinganling and Xiaoxinganling Mountains because of the relatively small investment needed as well as fewer production and operating risks. The engagement of worker households in the forest areas of Daxinganling and Xiaoxinganling Mountains in NTFPs business activities was still in a preliminary stage. Whether or not worker households engaged in NTFPs business activities was not affected by household head or household manpower characteristics; rather, worker households were more willing to engage in NTFPs business activities when the households had bank deposits, homes were close to the woodlands, the woodlands had good quality soil, and the households received social services.     

莲花山国家级自然保护区林下资源开发遇到难题及优化创新措施

以甘肃莲花山国家级自然保护区为例,主要介绍了保护区基本概况以及林下资源的情况,阐述了现阶段林下资源开发利用中存在的问题,并提出了林下资源开发利用的相关对策。     

Root stoichiometric dynamics and homeostasis of invasive species Phyllostachys edulis and native species Cunninghamia lanceolata in a subtropical forest in China

The community species abundance and diversity declined with bamboo invasion had been widely reported worldwide.However,the physiological strategies used during root competition between native species and invasive bamboo are poorly understood.To clarify the mechanisms underlying such strategies,the stoichiometric dynamics and homeostasis of nitrogen,phosphorus,organic carbon in root orders of Phyllostachys edulis(I du [=Ⅰ-Pe,years 1 and 2];Ⅱ du [=Ⅱ-Pe,years 3 and 4]),Cunninghamia lanceolata in transition and pure forests were analyzed.With increasing intensity of bamboo invasion,N,P,and C content of C.lanceolata root orders declined,N and P content in P.edulis rhizome orders declined,while C increased,the stoichiometric ratios in mixed forest interface mainly increased,and the stoichiometric differences within native and invasive species root orders narrowed.Meanwhile,the stoichiometric homeostasis index(H) of elements in the same root order and even the same elements in different root orders were not consistent.H of most root orders(except some H_P) was greater than 4,the H ranked order was Ⅰ-Pe Cl Ⅱ-Pe in mixed interfaces,and the N:P ratio of most species root orders was greater than 16,despite being affected by invasion.Our research concluded that the bamboo invasion narrows stoichiometric differences within root orders,and the juvenile bamboo rhizome has a stronger capacity for homeostatic regulation than in adult bamboo and C.lanceolata,which is a key determinant of bamboo invasion success.     

Growth,water relations,and survival of drought-exposed seedlings from six maternal families of honey mesquite (Prosopis glandulosa): responses to CO(2) enrichment

Low water availability is a leading contributor to mortality of woody seedlings on grasslands, including those of the invasive shrub Prosopis. Increasing atmospheric CO(2) concentration could favor some genotypes of this species over others if there exists intraspecific variation in the responsiveness of survivorship to CO(2). To investigate such variation, we studied effects of CO(2) enrichment on seedling survival in response to uniform rates of soil water depletion in six maternal families of honey mesquite (P. glandulosa Torr. var. glandulosa). Three families each from the arid and mesic extremes of the species' distribution in the southwestern United States were studied in environmentally controlled glasshouses. Relative water content at turgor loss and osmotic potential were not affected by CO(2) treatment. Increased atmospheric CO(2) concentration, however, increased growth, leaf production and area, and midday xylem pressure potential, and apparently reduced transpiration per unit leaf area of seedlings as soil dried. Consequently, CO(2) enrichment about doubled the fraction of seedlings that survived soil water depletion. Maternal families of honey mesquite differed in percentage survival of drought and in several other characteristics, but differences were of similar or of smaller magnitude compared with differences between CO(2) treatments. There was no evidence for genetic variation in the responsiveness of survivorship to CO(2). By increasing seedling survival of drought, increasing atmospheric CO(2) concentration could increase the abundance of honey mesquite where establishment is limited by water availability. Genetic types with superior ability to survive drought today, however, apparently will maintain that advantage in the future.     

Carbon dioxide enrichment improves growth, water relations and survival of droughted honey mesquite (Prosopis glandulosa) seedlings

Low water availability reduces the establishment of the invasive shrub Prosopis on some grasslands. Water deficit survival and traits that may contribute to the postponement or tolerance of plant dehydration were measured on seedlings of P. glandulosa Torr. var. glandulosa (honey mesquite) grown at CO(2) concentrations of 370 (ambient), 710, and 1050 micro mol mol(-1). Because elevated CO(2) decreases stomatal conductance, the number of seedlings per container in the elevated CO(2) treatments was increased to ensure that soil water content was depleted at similar rates in all treatments. Seedlings grown at elevated CO(2) had a greater root biomass and a higher ratio of lateral root to total root biomass than those grown at ambient CO(2) concentration; however, these seedlings also shed more leaves and retained smaller leaves. These changes, together with a reduced transpiration/leaf area ratio at elevated CO(2), may have contributed to a slight increase in xylem pressure potentials of seedlings in the 1050 micro mol mol(-1) CO(2) treatment during the first 37 days of growth (0.26 to 0.40 MPa). Osmotic potential was not affected by CO(2) treatment. Increasing the CO(2) concentration to 710 and 1050 micro mol mol(-1) more than doubled the percentage survival of seedlings from which water was withheld for 65 days. Carbon dioxide enrichment significantly increased survival from 0% to about 40% among seedlings that experienced the lowest soil water content. By increasing seedling survival of drought, rising atmospheric CO(2) concentration may increase abundance of P. glandulosa on grasslands where low water availability limits its establishment.     

Cloning of erect,thornless, non-browsed nitrogen fixing trees of Haiti's principal fuelwood species (Prosopis juliflora)

A progeny trial in Haiti compared 70 open-pollinated families ofProsopis representing seed sources from Haiti, Peru, Chile, Argentina and southwestern US. At the end of 4 years growth, the tallest 6 families were of Peruvian origin. Some of these Peruvian trees (probablyP. juliflora) were thornless, had erect habit and were non-browsed by goats, unlike other thornlessProsopis alba families from South America. Scions from the 5 tallest spineless and most erect trees were transported from Haiti to Texas A&I University where they were successfully grafted ontoP. alba rootstock. These scions should have great potential for grafting onto existing weedyProsopis and for grafting onto rootstock previously shown to tolerate salinities of seawater and pH values of 10.3.