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Sugarcane culture is replanted after five--eight successive harvests and intensely fertilised and mechanised. The influence on bacteria (total, nitrifying, denitrifying), fungi, microbial biomass-C, and dynamic processes (respiratory activity, N mineralisation, potential nitrification, P-solubilising activity) and enzymatic activities (dehydrogenase, urease, phosphatase) was studied for six successive harvests of the crop. The straw of the second and third harvest was burned. Soil microbial counts and activities were reduced after successive harvests. Fungi counts, N mineratisation, potential nitrification, and the P-solubilising, urease, and phosphatase activities decreased gradually from the first harvest to the third, increased again after the fourth, and then decreased again. Total, nitrifying, and denitrifying bacteria and fungi counts decreased, on average, 55, 22, 17, and 77%, respectively, in the sixth harvest in relation to the first. Reductions also occurred in microbial biomass-C (43%), respiratory activity (39%), N mineralisation (35%), potential nitrification (40%), and P-solubilising activity (35%). Reductions were observed in dehydrogenase (58%) and urease (36%) activities, but not in phosphatase activity. Successive sugarcane harvests may significantly influence microbial populations and activities, with harmful consequences to the C, N, and P cycles, and may decrease crop productivity. Additional keywords: bacteria, dehydrogenase, fungi, potential nitrification, respiratory activity, urease., Introduction Brazil, the world's largest producer of sugarcane, will process 598 Mt in 2009/2010 (Machado 2009). To maximise profit, several harvests are done, and then the sugarcane is replanted after [...]

Concerns about climate change and the desire to develop a domestic, renewable energy source are increasing the interest in forest biomass extraction, especially in the form of logging residues, i.e., tree tops and branches. We reviewed the literature to determine the site and soil conditions under which removal of logging residues along with the stem (i.e., whole-tree harvesting), especially at clearcut, results in negative impacts on soil productivity compared with conventional stem-only harvesting in boreal and temperate forests. Negative impacts of biomass harvesting on soil nutrient pools (e.g., nitrogen, phosphorus and base cations) and soil acid-base status are more frequent in the forest floor than in the mineral soil. In the first years post-harvest, however, biomass harvesting has the greatest potential to influence tree survival and growth, either positively or negatively, through its effects on microclimate and competing vegetation. Later in the rotation, impaired nitrogen and (or) phosphorus nutrition on whole-tree harvested sites has been shown to reduce tree growth for at least 20 years in some stands. Biomass removal can also reduce the concentrations of base cations in soils and foliage, but this has not, to date, been shown to affect tree productivity. There are no consistent, unequivocal and universal effects of forest biomass harvesting on soil productivity. However, climate and microclimate, mineral soil texture and organic C content, the capacity of the soil to provide base cations and phosphorus, and tree species autecology appear to be critical determinants of site sensitivity to biomass harvesting. Rigorous, long-term experiments that follow stand development through a rotation will facilitate the identification of categories of site or stand conditions under which negative impacts of biomass harvesting are likely. Key words: forest biomass, whole-tree harvesting, soil productivity, tree nutrition, stand productivity. Les preoccupations au sujet des changements climatiques et la volonte de developper des sources d'energie domestique renouvelable augmentent l'interet pour l'extraction de la biomasse forestiere, surtout sous la forme de residus de coupe, c.-a-d., les cimes et les branches des arbres. Les auteurs ont conduit une revue de litterature pour determiner les conditions de site et de sol pour lesquelles l'enlevement des residus de coupe en plus de la tige (c.-a-d., la coupe par arbre entier ), surtout lors de coupes a blanc, conduit a des impacts negatifs sur la productivite des sols comparativement a la recolte conventionnelle du tronc seulement, en forets boreales et temperees. Les impacts negatifs de la recolte de la biomasse sur les reserves du sol en nutriments (p. ex. azote, phosphore et cations basiques) et sur le statut acidite-alcalinite apparaissent plus frequents dans l'humus que dans le sol mineral. Cependant, au cours des premieres annees suivant la recolte, le prelevement de la biomasse montre le plus fort potentiel pour influencer la survie des arbres et leur croissance, soit positivement soit negativement, par ses effets sur le microclimat et la vegetation competitrice. Plus tard dans la revolution, on observe que pour certains peuplements, une nutrition amoindrie en azote et (ou) phosphore sur les sites avec coupe par arbre entier reduit la croissance des arbres pendant au moins 20 ans. Le prelevement de la biomasse peut egalement reduire les teneurs en cations basiques dans les sols et le feuillage, mais ceci ne semble pas se traduire en effet sur la productivite. Il n'y a pas d'effets non equivoques et universels de la recolte de la biomasse sur la productivite des sols. Cependant, le climat et le microclimat, la granulometrie du sol, sa teneur en C organique, sa capacite a fournir les cations basiques et le phosphore, ainsi que l'autecologie des especes semblent constituer des determinants importants de la sensibilite des sites a la recolte de la biomasse. Des experiences rigoureuses, conduites a long terme pour suivre le developpement des peuplements tout au long de la revolution, faciliteront l'identification des categories de sites ou les conditions des peuplements pour lesquels des impacts negatifs sont susceptibles de se developper. [Traduit par la Redaction], Introduction Biomass from forests and byproducts from the manufacturing of traditional forest products are increasingly used to generate a range of bioproducts, of which bioenergy is currently the most common. [...]

The impacts of plantation forest management on soil C stocks in New Zealand need to be better understood for the purposes of C accounting under the Kyoto Protocol. We investigated the impacts of three harvest residue management treatments on C and N stocks in a scoriaceous forest soil: whole-tree harvesting plus forest floor removal, whole-tree harvesting, and stem-only harvesting. Volumetric samples were collected from the forest floor and three mineral soil depth increments (0-0.1, 0.1-0.2, and 0.2-0.3 m) 16 to 17 yr after harvesting. Both fine (2-mm) fractions of the mineral soil were analyzed. No significant impacts on stocks of C and N were observed in the mineral soil fine fraction. Averaged across treatments, the 0-to 0.3-m mineral soil coarse fraction contained 5.2 [+ or -] 0.52 Mg C [ha.sup.-1], representing 25% of total mineral soil C, with most derived from the fine-earth-coated scoria gravel. The inclusion of the coarse fraction stocks enabled the detection of significant treatment effects. Stem-only harvesting (residue retention) had significantly larger C stocks in the 0-to 0.1-m total mineral soil (fine + coarse fractions), forest floor, and total soil (forest floor + 0-0.3-m total mineral soil) pools than whole-tree harvesting (residue removal) plus forest floor removal. We recommend the retention of both harvest residues and forest floor materials for the maintenance of soil C stocks in plantation forests. Detection of residue management impacts on C stocks in soils with vesicular gravels may require analysis of the coarse fraction. Abbreviations: FE whole-tree harvesting plus forest floor removal; FH, fermented or humic; L, litter; OM, organic matter; SO, stem-only harvesting; WT, whole-tree harvesting.

Rising concerns about greenhouse gases, increased fuel prices, and the potential for new high value agricultural products have raised interest in the use of maize stover for bioenergy production. However, residue harvest must be weighed against potential negative impacts on soil quality. This study, conducted in Chazy, NY, evaluated the long-term effects of 32 yr of maize (Zea mays L.) stover harvest vs. stover return on soil quality in the surface layer (5-66 mm) under plow till (PT) and no-till (NT) systems on a Raynham silt loam (coarse-silty, mixed, active, nonacid, mesic Aeric Epiaquept) using physical, chemical, and biological soil properties as soil quality indicators. Twenty-five soil properties were measured, including standard chemical soil tests, aggregate stability (WSA), bulk density, ([[rho].sub.b]) penetration resistance (PR), saturated hydraulic conductivity ([K.sub.s]), infiltrability (Infilt), several porosity indicators (aeration pores(PO > 1000), soil water potential = [PHI] > - 0.36 kPa; air-filled pores at field capacity (PO > 30), [PHI] > - 10kPa; available water capacity (AWC), - 1500 < [PHI] < - 10 kPa), total organic matter (OM), parasitic ([Nem.sub.Parasitic]) and beneficial nematode ([Nem.sub.Beneficial]) populations, decomposition rate (Decomp), potentially mineralizable N (PMN) and easily extractable (EEG) and total glomalin (TG). Only eight indicators were adversely affected by stover harvest, and most of these effects were signifcant only under NT. Almost all indicators affected by stover removal were affected equally or more adversely by tillage. A total of 15 indicators were adversely affected by tillage. Results of this study suggest that, on a silt loam soil in a temperate climate, long-term stover harvest had lower adverse impacts on soil quality than long-term tillage. Stover harvest appears to be sustainable when practiced under NT management. Abbreviations: [[rho].sub.b], bulk density; AWC, available water capacity; Decomp, cellulose decomposition rate; EEG, easily extractable glomalin concentration; [K.sub.s], saturated hydraulic conductivity; ln[K.sub.s], ln([K.sub.s] + 1); Infilt, infiltrability; NT, no-till; NT-H, NT stover harvested; NT-R, NT stover returned; [Nem.sub.Beneficial], number of beneficial nematodes; [Nem.sub.Parasitic] number of parasitic nematodes; OM, organic matter; PMN, potentially mineralizable nitrogen; PO > 30, pores with diam. > 30 [micro]m; PO > 1000, pores with diam. > 1000 [micro]m; PR, penetration resistance; PT, plow till; PT-H, PT stover harvested; PT-R, PT stover returned; SOC, soil organic carbon; TG, total glomalin concentration; WSA, water-stable aggregation (0.25-2.00 mm).

Most cervid populations in Europe and North America are managed through selective harvesting, often with age- and sex-specific quotas, with a large influence on the population growth rate. Less well understood is how prevailing weather affects harvesting selectivity and off-take indirectly through changes in individual animal and hunter behavior. The behavior and movement patterns of hunters and their prey are expected to be influenced by weather conditions. Furthermore, habitat characteristics like habitat openness are also known to affect movement patterns and harvesting vulnerability, but how much such processes affect harvest composition has not been quantified. We use harvest data from red deer ( Cervus elaphus) to investigate how weather and habitat characteristics affect behavioral decisions of red deer and their hunters throughout the hunting season. More specifically, we look at how sex and age class, temperature, precipitation, moon phase, and day of week affect the probability of being harvested on farmland (open habitat), hunter effort, and the overall harvest numbers. Moon phase and day of week were the strongest predictors of hunter effort and harvest numbers, with higher effort during full moon and weekends, and higher numbers during full moon. In general, the effect of fall weather conditions and habitat characteristics on harvest effort and numbers varied through the season. Yearlings showed the highest variation in the probability of being harvested on farmland through the season, but there was no effect of sex. Our study is among the first to highlight that weather may affect harvesting patterns and off-take indirectly through animal and hunter behavior, but the interaction effects of weather and space use on hunter behavior are complicated, and seem less important than hunter preference and quotas in determining hunter selection and harvest off-take. The consideration of hunter behavior is therefore key when forming management rules for sustainable harvesting. [ABSTRACT FROM AUTHOR]

Sustainable harvest of natural products that meets the needs of local people has been viewed by many as an important means for sustaining conservation projects. Although plants often respond to tissue damage through compensatory growth, it may not secure long-term sustainability of the populations because many plants enhance individual well-being at the expense of propagation. Sustainability may further be threatened by infrequent, large-scale events, especially ill-documented ones. We studied the impacts of sprout harvesting on sprout growth in a dwarf bamboo ( Pseudosasa usawai) population that has seemingly recovered from an infrequent, large-scale masting event. Experimental results suggest that although a single sprout harvest did not significantly alter the subsequent abundance and structure of sprouts, culm damage that accompanied sprout harvesting resulted in shorter, thinner, and fewer sprouts. Weaker recovery was found in windward, continually harvested, and more severely damaged sites. These findings suggest that sprout growth of damaged dwarf bamboos is likely non-compensatory, but is instead supported through physiological integration whose strength is determined by the well-being of the supplying ramets. Healthy culms closer to the damage also provided more resources than those farther away. Sustainable harvesting of sprouts could benefit from organized community efforts to limit the magnitude of culm damage, provide adequate spacing between harvested sites, and ensure sufficient time interval between harvests. Vegetation boundaries relatively resilient to infrequent, large-scale events are likely maintained by climatic factors and may be sensitive to climate change. Continual monitoring is, therefore, integral to the sustainability of harvesting projects. [ABSTRACT FROM AUTHOR]

Twelve 0.81-ha crabgrass (Digitaria ciliaris [Retz.] Koel.) hay fields were harvested at 21, 35, and 49 d of regrowth (average phonological growth stage of 30, 51, and 56, respectively). Increased harvest interval exhibited a linear decrease (P [less than or equal to] 0.01) in CP (14.1, 13.7, and 10.6% of DM, respectively) and increase (P [less than or equal to] 0.01) in NDF (65.3, 70.6, and 70.2% of DM, respectively) and ADF (35.7, 38.9, and 42.7% of DM, respectively). Hays were incorporated into 3 diets that contained 20% (DM basis) crabgrass hay, ground corn (33%), and soybean hulls (32%). Diets contained 14.4, 14.4, and 13.6% CP; 1.83, 1.72, and 1.81 Mcal of N[E.sub.m]/ kg; and 1.21, 1.10, and 1.17 Mcal of N[E.sub.g]/kg; respectively. Diets were fed to beef calves in 12 pens at a rate of 2.3% (DM basis) of BW in 1 experiment (n = 120, initial BW 210 [+ or -] 4.4 kg) and ad libitum in another experiment (n = 60, initial BW 207 [+ or -] 4.4 kg). To measure passage rate of the hay and concentrate portions of the diets, 12 heifer calves (BW = 145 [+ or -] 4.5 kg) were individually fed at 2.3% of BW for 14 d and dosed with Dy-labeled soybean hulls and Yb-labeled hay. In situ DM digestibility of the hays and diets were determined using 3 ruminally cannulated steers (BW = 584 [+ or -] 10.4 kg). Harvest interval did not affect (P [greater than or equal to] 0.11) ADG of limit-fed calves during the diet acclimation or growing phases (average 0.32 and 0.80 kg, respectively) or ADG of calves fed ad libitum (average 1.21 kg). Dry matter intake of calves fed ad libitum averaged 7.9 kg/d (3.28% of BW) and was not affected (P [greater than or equal to] 0.22) by harvest interval. Gain:feed was not affected (P [greater than or equal to] 0.20) by harvest interval (0.13 and 0.15 for limit-fed and ad libitum-fed calves, respectively). Increased harvest interval linearly increased (P [less than or equal to] 0.01) ruminal retention time of the hay and tended (P = 0.06) to linearly increase ruminal retention time of the concentrate portions of the diet. Harvest interval linearly decreased (P [less than or equal to] 0.05) the extent of degradability and effective degradability of DM and NDF of hays, but DM disappearance of the total diet did not differ (P [greater than or equal to] 0.35). In the conditions of this study, increasing harvest interval of crabgrass hay from 21 to 49 d had no deleterious impact on animal performance or efficiency of gain when fed to growing calves in a high-concentrate mixture. Key words: cattle, Digitaria ciliaris, growth, hay quality

Our objective was to determine if harvest in the morning (AM, 0600) vs. the afternoon (PM, 1800) affects composition and voluntary DMI of gamagrass (GG) or switchgrass (SG) stored as baleage. Iuka GG (Tripsacum dactyloides L.) and Alamo SG (Panicum virgatum L.) were cut with a mower-conditioner, immediately round-baled, wrapped in plastic, and stored as baleage. Beef steers (255 [+ or -] 7 kg of BW) were assigned (5 steers/treatment) to GG/AM, GG/PM, SG/AM, or SG/ PM. Ad libitum intake was measured for 21 d (7-d adjustment and 14-d intake estimate) followed by 7-d adjustment and 5-d digestion and N balance study. Chewing behavior was recorded during the balance study. Compared with AM, PM had more (P < 0.01) starch (9.3 vs. 4.7 g/kg of DM), total nonstructural carbohydrate (30.4 vs. 19.0 g/kg of DM), and monosaccharides (17.1 vs. 11.2 g/kg of DM). Compared with AM, PM had less (P = 0.05) acetate (13.0 vs. 18.6 g/kg of DM) and propionate (0.29 vs. 0.82 g/kg of DM) and tended (P < 0.13) to have less lactate (2.9 vs. 3.5 g/kg of DM) and butyrate (3.9 vs. 5.1 g/kg of DM). Compared with SG, GG had more (P = 0.01) DM (324 vs. 242 g/kg of baleage), CP (114 vs. 97 g/kg of DM), lactate (4.8 vs. 1.6 g/kg of DM), starch (9.4 vs. 4.7 g/kg of DM), total nonstructural carbohydrate (34.2 vs. 15.2 g/kg of DM), and monosaccharides (20.8 vs. 7.4 g/kg of DM). However, GG had a lower (P = 0.01) pH (5.32 vs.5.79) and less (P < 0.01) ethanol (18.7 vs. 27.3 g/kg of DM), acetate (12.3 vs. 19.2 g/kg of DM), propionate (0.00 vs. 1.11 g/kg of DM), and butyrate (0.6 vs. 8.4 g/kg of DM). Daily DMI (2.16 vs. 1.83% of BW) and digestible DMI (1.15 vs. 0.95% of BW) were greater (P = 0.03) for PM than AM. Plasma urea N concentrations at the end of the ad libitum intake phase were greater (P = 0.01) for AM (3.91 mM) than for PM (2.31 mM) and greater (P = 0.07) for GG (3.51 mM) than for SG (2.71 mM). Steers fed PM spent more time eating (P = 0.04) and less time resting (P = 0.01) during meals than steers fed AM. Apparent digestibility of DM and fiber components was not affected (P < 0.18) by treatment. Apparent digestibility and retention of N decreased from PM to AM for SG, but increased for GG (P = 0.05). Retention of N as a percentage of N intake or N digested decreased more from PM to AM for SG than for GG (P < 0.05). We conclude that increased nonstructural carbohydrate content of the PM harvest of these grasses stored as baleage caused increased voluntary intake and improved use of dietary N by beef steers. Key words: beef steer, diurnal harvest, gamagrass, silage, switchgrass

The amount of food left by a forager after feeding in a depletable patch of known volume, the giving-up density (GUD), estimates the quitting harvest rate. I constructed a feeder for measuring GUD in Egyptian fruit bats (Rousettus aegyptiacus). The feeder contained liquid food mixed with pieces of hose that interfered with the drinking behavior of the bats and forced them to work progressively harder to obtain more food as the depth of the liquid in the feeder decreased. Harvest rates in bats using these feeders declined with time. When presented with feeders containing different initial food densities, the bats equalized GUD and consumed proportionately more food from rich patches than from poor ones. Thus, the bats recognized patches of different quality and foraged following a fixed quitting harvest rate patch-use strategy. Key words: Egyptian fruit bats, frugivory, giving-up density, harvest rates, optimal foraging, patch use, resource assessment, Rousettus aegyptiacus

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.apergo.2005.11.006 Byline: Sarp Korkut Sumer (a), Sait M. Say (b), Fikri Ege (c), Alaettin Sabanci (b) Keywords: Noise level; Combine harvester; Cab Abstract: A considerable number of the combine harvesters in Turkey are rather old and used without cabs resulting in unhealthy working conditions for their operators. Noise is one of the detrimental factors. This study deals with determining and comparing the noise exposed on the operators of the combines with and without a cab used for wheat harvesting in Turkey. The sound pressure levels (dB) at octave band center frequencies (31.5-8000Hz) and the sound levels (dBA) at the ear level of the operators were measured on 37 different combine harvesters with four different makes and different years from 1976 to 2001. Fifteen of the combines were without a cab, another 15 had original cabs while remaining seven combines had cabs mounted on them after manufacturing. The sound pressure levels were in a decreasing trend from the lower frequencies to higher frequencies. This trend was more noticeable for the combines with original cab and with the cab mounted after manufacturing compared to the ones without cab. The use of a cab was more effective in the insulation of the noise at the medium and higher frequencies, which have more bothersome effect compared to the lower frequencies. The sound pressure levels were 75-102dB and 46-89dB at low (31.5-500Hz) and high (500-8000Hz) frequencies for all combines, respectively. The sound pressure levels at the frequency of 4000Hz at which the human ear is most sensitive were 6-17dB lower for the combines with the cabs mounted after manufacturing and 9-28dB lower for the ones with the original cabs compared to the combines without cab. The sound levels were 85-90, 81-83, and 76-81dBA for the combines without cab, with cab mounted after manufacturing, and with original cab, respectively. The study showed that the use of a cab was useful in the insulation of the noise, particularly at higher frequencies. In addition, it protects the operator from the factors having detrimental effects on the working efficiency such as high temperature and dusty environment. The authors strongly recommend mounting of a cab on to the combines currently being used without a cab in rental system in Turkey to provide healthy working conditions for their operators. Author Affiliation: (a) Department of Agricultural Machinery, Faculty of Agriculture, Aanakkale Onsekiz Mart University, 17020 TerzioAlu, Aanakkale, Turkey (b) Department of Agricultural Machinery, Faculty of Agriculture, University of Aukurova, 01330 Balcali, Adana, Turkey (c) Department of Industrial Engineering, Faculty of Engineering, University of Aukurova, 01330 Balcali, Adana, Turkey Article History: Received 20 May 2004; Accepted 4 November 2005

Despite growing interest in traditional and local ecological knowledge for conservation and resource management, the role of migrant resource users is largely unexplored. Challenging many assumptions about what constitutes "local knowledge," migrant and immigrant harvesters of non-timber forest products on the Olympic Peninsula, Washington possess useful ecological knowledge of overstory-understory relationships and how forestry practices affect understory biological and commercial production. Harvesters of salal (Gaultheria shallon), a shrub used in the multi-million dollar floral greens industry, were interviewed in Mason County, Washington in 2001-2003. Interviews revealed that harvesters possess different kinds of resource management knowledge depending on whether they are experienced harvesters or more recent newcomers to the area. These differences may also correlate with differences in their harvesting practices. Understanding how resource management knowledge differs between experienced and newcomer harvesters can inform forest managers in their efforts to develop effective management and permitting policies for floral greens and other non-timber forest resources in the Pacific Northwest of the United States. Key words Local ecological knowledge * nontimber forest products * sustainable resource management * Gaultheria shallon (salal) * Pacific Northwest * harvest.

Intensively managed forests are among the most important sources of wood fiber and timber in the southern United States. There is a great deal of concern that wet-weather harvesting disturbances might diminish long-term soil-site productivity. Determining the true effect of harvesting disturbance and silvicultural treatments on long-term productivity of pine plantations is difficult because growth and yield are affected by changes in climate, silviculture, and genetics. Change in productivity rank among treatments was used as a new approach to evaluate harvest disturbance effects on changes in soil-site quality because it is less influenced by the confounding factors that affect tree growth. Three 20-ha loblolly pine (Pinus taeda L.) plantations were subjected to combinations of wet- and dry-weather harvesting and mechanical site preparations. Wet-weather harvesting had no discernable effect at the operational scale (3.3 ha) compared to dry harvesting on changes in soil-site quality when standard site preparation methods were used; however, results based on change in rank for site index indicated that the combination of wet harvesting and flat planting diminished productivity. Polypedon-scale (0.008 ha) investigations indicated that silviculture, inherent site factors, and disturbance affected drainage and changes in soil-site productivity. This study showed that the industrial practice of bedding maintained site productivity of wet-weather harvested stands on wet pine flats. These results are potentially important to nonindustrial private landowners whose plantations are not commonly bedded before replanting.

ABSTRACT. The Chipewyan Dene or Denesoline have long been dealing with variability in the movements of barren-ground caribou (Rangifer tarandus). Many generations ago, Denesoline hunters learned that by observing caribou [...]

Byline: Arild Wikan (1) Keywords: words or phrases: Population dynamics; Harvest; (de)Stabilizing effects; Age structure; Bifurcation Abstract: The role of harvest in discrete age-structured one-population models has been explored. Considering a few age classes only, together with the overcompensatory Ricker recruitment function, we show that harvest acts as a weak destabilizing effect in case of small values of the year-to-year survival probability P and as a strong stabilizing effect whenever the survival probability approaches unity. In the latter case, assuming n=2 age classes, we find that harvest may transfer a population from the chaotic regime to a state where the equilibrium point (x.sub.1*, x.sub.2*) becomes stable. However, as the number of age classes increases (which acts as a stabilizing effect in non-exploited models), we find that harvest acts more and more destabilizing, in fact, when the number of age classes has been increased to n=10, our finding is that in case of large values of the survival probabilities, harvest may transfer a population from a state where the equilibrium is stable to the chaotic regime, thus exactly the opposite of what was found in case of n=2. On the other hand, if we replace the Ricker relation with the generalized Beverton and Holt recruitment function with abruptness parameter larger than 2, several of the conclusions derived above are changed. For example, when n is large and the survival probabilities exceed a certain threshold, the equilibrium will always be stable. Author Affiliation: (1) Harstad College, Havnegata 5, 9480, Harstad, Norway Article History: Registration Date: 01/01/2003 Received Date: 04/02/2003 Online Date: 02/01/2004 Article note: Revised version: 18 September 2003

Forest harvesting and site preparation alter many features of the soil environment affecting biological activity and litter decomposition. One aspect of biological activity, 'lignocellulase' enzyme activity, has been found to be a good predictor of litter mass loss. We determined the effects of postharvest treatments (SLASH, BROADCAST BURN, and CHIP AND PILE treatments with the intact FOREST treatment as a control) on lignocellulose degrading and nutrient releasing enzyme activities ([beta]-glucosidase, cellobiohydrolase, [beta]-xylosidase, N-acetyl-glucosaminidase, phenol oxidase, and phosphatase) in decomposing pine litter in litterbags and in the forest floor and compared them with patterns of decomposition. In the forest floor, the SLASH treatment decreased phenol oxidase and phosphatase activities by half; the CHIP AND PILE treatment decreased [beta]-glucosidase, cellobiohydrolase, phenol oxidase, and phosphatase activities by 50 to 75%; and the BROADCAST BURN treatment decreased N-acetylglucosaminidase, phenol oxidase, and phosphatase activities by 30 to 60%. In the litterbag litter, phenol oxidase activity, N-acetyl-glucosaminidase activity, and mass loss were lower in the BROADCAST BURN treatment than in the FOREST treatment. SLASH and CHIP AND PILE treatments did not affect enzyme activities or decomposition of the litterbag litter. The relationship between enzyme activities and incremental mass loss was significant in the FOREST and CHIP AND PILE treatments for [beta]-glucosidase, cellobiohydrolase, and N-acetyl-glucosaminidase enzymes (r > 0.50, p < 0.05), but not significant in the BROADCAST BURN and SLASH treatments. Although reduced enzyme activities were accompanied by lower decomposition rates, enzyme activities were not always a dominant control of decomposition in certain highly disturbed treatments.

Several indicators have been identified for the conservation and maintenance of soil criterion in the Montreal Protocol. The objective of this study was to use soil compaction and disturbance measures to determine harvesting impacts at a landscape scale in the boreal forest of Saskatchewan. Forest harvesting impacts were studied pre and postharvest for five harvested sites by (i) sampling soil bulk density ([D.sub.b]) at prescribed grid-points, and (ii) measuring soil disturbance regimes on two 30-m transects at each grid-point. Mean soil [D.sub.b] in the harvested area increased significantly (8-11%) from pre to postharvest conditions for the two winter-harvested sites at both the 10- and 20-cm depths, while two of the three summer harvested sites also showed significant [D.sub.b] increases (7-15%) at the 10-cm depth. Combining all five sites, showed that after harvest 32% of all the grid-points had an increased [D.sub.b] of >15%. Mean soil [D.sub.b] at a 10-cm depth for roadways and landings was significantly higher (8-14%) than postharvest [D.sub.b] for postharvest levels at four of the five harvested sites. Surface soil disturbance regimes were higher for the summer-harvested sites than that for the winter-harvested sites. Landscape position showed no significant differences in [D.sub.b] between the shoulder, backslope, and footslope positions; however, within each landscape position, significant differences in [D.sub.b] were found between pre and postharvest conditions. Soil [D.sub.b] and soil disturbance regimes measured on a grid basis provided a simple, but reliable method for monitoring soil compaction and disturbance effects from harvesting at a landscape scale.

Bioenergy crops are often classified (and subsequently regulated) according to species that have been evaluated as environmentally beneficial or detrimental, but in practice, management decisions rather than species per se can determine the overall environmental impact of a bioenergy production system. Here, we review the greenhouse gas balance and 'management swing potential' of seven different bioenergy cropping systems in temperate and tropical regions. Prior land use, harvesting techniques, harvest timing, and fertilization are among the key management considerations that can swing the greenhouse gas balance of bioenergy from positive to negative or the reverse. Although the management swing potential is substantial for many cropping systems, there are some species (e.g., soybean) that have such low bioenergy yield potentials that the environmental impact is unlikely to be reversed by management. High-yielding bioenergy crops (e.g., corn, sugarcane, Miscanthus, and fast-growing tree species), however, can be managed for environmental benefits or losses, suggesting that the bioenergy sector would be better informed by incorporating management-based evaluations into classifications of bioenergy feedstocks. [ABSTRACT FROM AUTHOR]

Sustainable management of exploited species is an ongoing challenge, particularly where populations have collapsed or been depleted by overharvest and habitat alteration. The walleye (Sander vitreus) population in Lake Superior's Black Bay historically supported more than 90% of the commercial walleye harvest from the entire lake, but collapsed in 1968 and has still not recovered despite long‐term closure of the fishery. In an effort to rehabilitate this population, hatchery‐origin walleye from exogenous sources were released into Black Bay between 2003 and 2005. We used individual‐based analysis of genetic data collected between 2007 and 2010 to examine the contributions of different wild sources and hatchery stocking events to the contemporary walleye population in Black Bay. We found that 75% of the walleye in Black Bay originated from above‐ and below‐barrier native populations in the Black Sturgeon River. The hatchery stocking events differed considerably in their effectiveness: the 2003 release of fry had no measurable contribution, whereas the 2004 and 2005 releases of fingerlings contributed 71% and 45% of the fish in their respective age classes. Hatchery and wild fish were similar in size, but hatchery fish rarely utilized the river habitat where Black Bay walleye historically spawned, and there was little genetic evidence of interbreeding or natural recruitment of stocked fish. Overall, our results suggest that restoring habitat connectivity to facilitate wild recruitment has greater potential than further exogenous stocking to contribute to the recovery of walleye in this system. [ABSTRACT FROM AUTHOR]

Well-informed management of harvested species requires understanding how changing ecological conditions affect demography and population dynamics, information that is lacking for many species. We have limited understanding of the relative influence of carnivores, harvest, weather and forage availability on elk Cervus elaphus demography, despite the ecological and economic importance of this species. We assessed adult female survival, a key vital rate for population dynamics, from 2746 radio-collared elk in 45 populations across western North America that experience wide variation in carnivore assemblage, harvest, weather and habitat conditions., Proportional hazard analysis revealed that 'baseline' (i.e. not related to human factors) mortality was higher with very high winter precipitation, particularly in populations sympatric with wolves Canis lupus. Mortality may increase via nutritional stress and heightened vulnerability to predation in snowy winters. Baseline mortality was unrelated to puma Puma concolor presence, forest cover or summer forage productivity., Cause-specific mortality analyses showed that wolves and all carnivore species combined had additive effects on baseline elk mortality, but only reduced survival by <2%. When human factors were included, 'total' adult mortality was solely related to harvest; the influence of native carnivores was compensatory. Annual total mortality rates were lowest in populations sympatric with both pumas and wolves because managers reduced female harvest in areas with abundant or diverse carnivores., Mortality from native carnivores peaked in late winter and early spring, while harvest-induced mortality peaked in autumn. The strong peak in harvest-induced mortality during the autumn hunting season decreased as the number of native carnivore species increased., Synthesis and applications. Elevated baseline adult female elk mortality from wolves in years with high winter precipitation could affect elk abundance as winters across the western US become drier and wolves recolonize portions of the region. In the absence of human harvest, wolves had additive, although limited, effects on mortality. However, human harvest, and its apparent use by managers to offset predation, primarily controls overall variation in adult female mortality. Altering harvest quotas is thus a strong tool for offsetting impacts of carnivore recolonization and shifting weather patterns on elk across western North America. [ABSTRACT FROM AUTHOR]

Mathematical models are used to explore the evolutionary and demographic consequences of size-selective harvesting and natural selection in populations with discrete, nonoverlapping generations. We specify the harvesting intensity and size selectivity in terms of both the phenotypic criterion for harvesting and the demographic goal of harvesting. The phenotypic criterion is defined by a threshold that specifies the minimum size of individuals harvested, while the demographic goal defines the desired catch or escapement from the harvest. Models use either a constant phenotypic threshold, or a variable phenotypic threshold that moves each year to remain a fixed distance from the mean size prior to harvest. Demographic goals are defined as a desired yield or escapement, measured in abundance or biomass. We find that all combinations of phenotypic criteria and demographic goals can produce evolutionary changes in equilibrium mean size and abundance when harvesting is size selective. Reductions in mean size are more severe under harvesting scenarios for which it is not possible to fully satisfy the demographic goals of harvesting at equilibrium. Models with a variable phenotypic threshold always produce a characteristic equilibrium for mean size and abundance for a given set of harvesting and natural selection parameters, regardless of the initial population characteristics. For some combinations of parameters, constant-threshold models produce alternative equilibria for the mean size and abundance. Our results suggest that the evolutionary effects of selective harvesting warrant consideration in long-term conservation and management planning. Key words: alternate equilibria; conservation of exploited populations; demography of harvested stocks; directional fecundity selection; evolution of length; fisheries management; harvesting selection; stabilizing viability selection.

The role of harvest in the dynamics of waterfowl populations continues to be debated among scientists and managers. Our perception is that interested members of the public and some managers believe that harvest influences North American duck populations based on calls for more conservative harvest regulations. A recent review of harvest and population dynamics of North American mallard ( Anas platyrhynchos) populations (Pöysä et al. 2004) reached similar conclusions. Because of the importance of this issue, we reviewed the evidence for an impact of harvest on duck populations. Our understanding of the effects of harvest is limited because harvest effects are typically confounded with those of population density; regulations are typically most liberal when populations are greatest. This problem also exists in the current Adaptive Harvest Management Program (Conn and Kendall 2004). Consequently, even where harvest appears additive to other mortality, this may be an artifact of ignoring effects of population density. Overall, we found no compelling evidence for strong additive effects of harvest on survival in duck populations that could not be explained by other factors. © 2012 The Wildlife Society. [ABSTRACT FROM AUTHOR]

Abundant and continuous old forest tend to be fragmented into isolated and small patches because of human harvest activities. Dispersive and isolated old forest patches cannot provide abundant interior habitat to wildlife, which is a fatal threat for specific plant communities and wildlife species. In this paper, an Integer Programming model for forest planning is designed to maximize the economical benefit of the forest and to guarantee a minimum area of interior old forest for wildlife habitat, the so-called core area satisfying minimum mature age requirements. The minimum core area constraints, to some degree, can help mitigate the negative impact of harvest activities to divide forest habitat into many small patches. The model is implemented in a commercial Integer Programming solver and it is applied to several hypothetical landscapes. The results show the possibility of incorporating a core area requirement into a forest planning model, and the possibility to obtain solutions within a reasonable computational time. Instances with up to 1600 management units have been solved in seconds to an optimality gap of 1% (0.1% in some cases). [ABSTRACT FROM AUTHOR]

Abstract: Previous studies have shown that clearcutting of northern hardwood forests mobilizes base cations, inorganic monomeric aluminum (Alim), and nitrate (NO3 −-N) from soils to surface waters, but the effects of partial harvests on NO3 −-N have been less frequently studied. In this study we describe the effects of a series of partial harvests of varying proportions of basal area removal (22%, 28% and 68%) on Alim, calcium (Ca2+), and NO3 −-N concentrations in soil extracts, soil water, and surface water in the Catskill Mountains of New York, USA. Increases in NO3 −-N concentrations relative to pre-harvest values were observed within a few months after harvest in soils, soil water, and stream water for all three harvests. Increases in Alim and Ca2+ concentrations were also evident in soil water and stream water over the same time period for all three harvests. The increases in Alim, Ca2+, and NO3 −-N concentrations in the 68% harvest were statistically significant as measured by comparing the 18-month pre-harvest period with the 18-month post-harvest period, with fewer significant responses in the two harvests of lowest intensity. All three solutes returned to pre-harvest concentrations in soil water and stream water in the two lowest intensity harvests in 2–3 years compared to a full 3 years in the 68% harvest. When the results of this study were combined with those of a previous nearby clearcut and 40% harvest, the post-harvest increases in NO3 −-N concentrations in stream water and soil water suggest a harvesting level above which the relation between concentration and harvest intensity changes; there was a greater change in concentration per unit change in harvest intensity when basal area removal was greater than 40%. These results indicate that the deleterious effects on aquatic ecosystems previously demonstrated for intensive harvests in northern hardwood forests of northeastern North America that receive high levels of atmospheric N deposition can be greatly diminished as harvesting intensity decreases below 40–68%. These results await confirmation through additional incremental forest harvest studies at other locations throughout the world that receive high levels of atmospheric N deposition. [Copyright &y& Elsevier]

Numerical experiments were developed using different water table depths and soil textures to investigate the impact of aspen harvesting on hydrological processes on the Western Boreal Plain. The effect of harvesting on soil moisture dynamics, fluxes at the water table, and water table fluctuation were compared for different harvesting scenarios simulated under wet and dry climatic cycles. Strong interaction between shallow water tables (i.e., 2 m) and atmospheric variability is observed for all soil textures and is reduced as the vadose zone thickens, particularly after a dry cycle, as a series of positive net atmospheric fluxes are needed to reduce soil moisture storage in order for recharge to occur. Because of harvesting, the water table fluxes can increase by 50 mm month−1, while on a yearly basis, this increase can reach 200 mm yr−1, with rainfall events taking between 1 and 5 years to become recharge (i.e., time lag). Also, the water table is expected to rise between 1 and 3.5 m, with rainfall-water table rise time lags of 1-3 years; however, the peak manifestation of harvesting on water table elevation can take up to 7 years after harvesting. The effects of aspen harvesting are more pronounced during wet cycles, and the development of forestry activities in the Boreal Plain should consider not only preceding precipitation but also the preceding precipitation-reference evapotranspiration ratio, water table depth, and soil texture. The interaction of these factors needs to be considered in order to develop sustainable forestry plans and avoid waterlogging conditions. [ABSTRACT FROM AUTHOR]

A dynamic model of forest ecosystems was used to investigate the effects of climate change, atmospheric deposition and harvest intensity on 48 forest sites in Sweden (n = 16) and Switzerland (n = 32). The model was used to investigate the feasibility of deriving critical loads for nitrogen (N) deposition based on changes in plant community composition. The simulations show that climate and atmospheric deposition have comparably important effects on N mobilization in the soil, as climate triggers the release of organically bound nitrogen stored in the soil during the elevated deposition period. Climate has the most important effect on plant community composition, underlining the fact that this cannot be ignored in future simulations of vegetation dynamics. Harvest intensity has comparatively little effect on the plant community in the long term, while it may be detrimental in the short term following cutting. This study shows: that critical loads of N deposition can be estimated using the plant community as an indicator; that future climatic changes must be taken into account; and that the definition of the reference deposition is critical for the outcome of this estimate. [Copyright &y& Elsevier]

The majority of our knowledge of harvested populations has been drawn from studies on single-species occupying continuous landscapes. Population dynamics in spatially structured landscapes are markedly different from those in continuous habitats. We investigate the effects of several harvesting strategies on the metapopulation dynamics of the bruchid beetle Callosobruchus maculatus and its parasitoid Anisopteromalus calandrae, when locally extinction prone populations of bruchids were harvested. By harvesting the resource in this closed resource-consumer interaction, we could examine the scenario where humans and natural predators share a common resource. Using population-level models in single and coupled-patch systems, simulations were run to estimate sustainable harvesting levels for each harvesting strategy. These harvesting levels were then implemented in experimental metapopulation microcosms. Experiments were run for multiple generations and long-term time series of population size and harvest yield were collected. Controversially, harvesting resulted in larger regional population sizes in harvested metapopulations than in unharvested metapopulations. Similarly, conservative harvesting strategies such as fixed escapement harvesting and harvesting with refuges resulted in smaller population sizes than fixed quota or fixed proportion harvesting strategies. Fixed proportion harvesting gave rise to the largest population sizes, fewest local extinctions and largest yields. Assuming both species are of ecological importance, fixed proportion is therefore the optimal harvesting strategy for this model system. Synthesis and applications. We demonstrate that, under certain conditions, increasing local mortality can increase population sizes. This 'hydra effect' may be caused by the advantage of higher rates of local population turnover for dispersive species in patchy landscapes, or due to the interruption of overcompensatory density-dependence in the host populations. These results are of particular relevance both in the development of sustainable harvesting policies in multi-species communities or, conversely, the control of pest species inhabiting spatially structured landscapes. We have shown that predictive models can be a useful tool in the estimation of sustainable harvesting limits where no a priori knowledge of the system exists. We also demonstrate that spatial structure, the effects of interspecific interactions and knowledge of density-dependent population dynamics must be included in the generation of sustainable harvesting theory. [ABSTRACT FROM AUTHOR]

Harvest of furbearers through trapping has been challenged by anti-trapping organizations for centuries, with organizational goals often including prohibition of all forms of trapping. Challenges to trapping may also include dissention among state wildlife agencies, pro-hunting organizations, and pro-trapping organizations. Despite recent efforts by anti-trapping organizations and occasional dissention among consumptive-use groups, national trends in snaring regulations included less restrictive regulations through time. This positive trend may offer opportunities for state wildlife agencies and pro-trapping organizations to enhance the public image of trapping, increase recruitment of trappers, and reverse the increasing trend of wildlife damage and associated costs. We offer support and suggestions to state wildlife agencies and pro-trapping organizations to help achieve these goals, with their partnership likely having a synergistic effect. Although we attempt to illuminate approaches for increasing support for trapping within the constraints of the cultural norms of the United States, we hope our approaches are useful to and promote dialogue in other jurisdictions experiencing similar problems. [ABSTRACT FROM AUTHOR]

Thirty natural populations of American ginseng (Panax quinquefolius L.) were censused twice annually for five to 11 years to monitor the rate, frequency, and intensity of root harvest. Over this period, 43% of populations were harvested and ca. 10% of plants was removed by harvesters. On an annual basis, 15% of populations were harvested and 1.3% of individuals were confirmed harvested. Both rates are likely underestimates of actual rates since we used conservative criteria to recognize harvest. Nearly half of the harvested populations were harvested more than once. Harvesters removed a small proportion of plants from populations; however, they frequently took non-reproductive and small plants, making the effect of harvest more destructive. In addition, violations of regulations regarding season, location, and plant size were common (20%, 65%, and 82% of events, respectively). Only 6% of harvest events were legal and 1.4% of plants were legally harvested in all three respects at the study sites. Two illegal harvests were documented carefully because they occurred at or near census points. These harvests highlighted the proximal factors that result in unsustainable harvest practices: (I) removal of adult plants prior to ripening of seeds, thus precluding the proper planting of propagules for population recovery; (2) removal of plants that are under the legal size limit, with no ability of dealers or buyers to detect this violation; and (3) removal of plants from land in which harvest is strictly prohibited, and the associated difficulty of enforcing such rules. We discuss policy options that could contribute to addressing these problems. [ABSTRACT FROM AUTHOR]

Copyright of Agricultural Research in the Tropics / Pesquisa Agropecuária Tropical is the property of Pesquisa Agropecuaria Tropical and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The article presents a study that examines the harvesting patterns in relation to size and sex preferences of coconut crabs or Birgus latro and its effect on the reproduction. It states that a market research was performed at the Ishigaki Island, part of the Sakishima archipelago in Okinawa, Japan, and field investigations on Hatoma Island. It mentions that the sex and thoracic length (TL) of the harvested population of coconut crabs were recorded and evaluated. It reveals that the harvesting patterns reflect the biases in the sex and body size of the coconut crabs wherein larger males are usually taken. The study indicates that the said biases affect the reproductive output of coconut crabs due to reduction in potential mates for female coconut crabs.

Copyright of Forestry Chronicle is the property of Canadian Institute of Forestry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Forestry Chronicle is the property of Canadian Institute of Forestry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Plant samples from wild populations of Hypericum triquetrifolium were collected from different sections of Jordan and introduced for cultivation under nitrogen fertilization treatments for 2 years. The cultivated populations varied widely in plant height, width, dry weight, hypericin content, number of days to flowering and fruit capsule formation, and response to nitrogen fertilization. In general, hypericin content of the plant tissue increased as growth approached full flowering and started to decrease at the fruiting stage. A population sampled near Ramtha produced the highest hypericin content (0.156%) at the first stage of flowering, yielding about 9284 kg ha-1 of dry herb (14.5 kg ha-1 of dry hypericin) under nitrogen fertilization. Wild H. triquetrifolium populations are an important source for evaluation and improvement for the cultivation of this species. [ABSTRACT FROM AUTHOR]

Abstract: Pentadesma butyracea Sabine (Clusiaceae) is a multi-purpose tree that provides non-timber forest products (NTFPs). In particular, fruit almonds can be transformed into butter for cooking and cosmetics. During the present study, the following hypotheses were tested: (i) diameter structure of P. butyracea populations is independent of its fruit gathering intensity; (ii) P. butyracea seedling and sapling density and origin are independent of its fruit gathering intensity; (iii) P. butyracea fruit gathering and processing of its almonds are profitable activities and (iv) P. butyracea fruit collectors and almond transformers are receiving the lowest marketing margins in the commercial channel. The class distribution in the low-intensity harvesting sites showed a typical inverse J-shaped curve whereas the high-intensity harvesting ones showed an almost bell curve (G 2 =23.93, p =0.0008). After data analysis, all hypotheses turned out to be wrong except the hypothesis (iii). In order to assess the effects of fruit harvesting on natural regeneration of P. butyracea, we compared seedling and sapling density of regeneration originating from seeds and roots suckers in plots that had been differentiated according to fruit harvesting intensity. These plots were laid out in riparian forests, which are the natural habitats for the species in Benin. Observed seedling and sapling density was high (13,872±7886 seedlings and saplings/ha) in low-intensity harvesting sites but very low (4200±3810 seedlings and saplings/ha) in high-intensity harvesting sites (F =17.16; p =0.0006). However, there was no significant difference between root sucker density in either type of harvesting site (F =0.79; p =0.3861). Collection of P. butyracea fruits and subsequent processing of its almonds into butter is an important source of income for women involved in these activities. Commercial margin analysis showed that these women involved in almonds and butter trade, far from being exploited by traders, recuperate between 49% and 80% of the price paid by the consumer, depending on the quality of the product and the length of commercial channel used. [Copyright &y& Elsevier]

Copyright of Journal of Environmental Engineering & Landscape Management is the property of Vilnius Gediminas Technical University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Harvesting of legume trees in the border between Organ Pipe National Monument in Arizona and Sonora, Mexico, may affect mesquite and ironwood trees in the park. The Sonoyta Valley is the southern bondary of the park and legume trees have been harvested there since 1975.

The article presents the study on the net primary production (NPP) of the U.S Midwest croplands. It states that counties in several states including Illinois, Indiana, and Iowa had coverage of several crops including oats, barley, and corn. It mentions that areas of highest NPP were dominated by the cultivation of corn and soybean.

The population density of large-bodied lizards may be impacted by single-tree harvesting practices in the Amazonian rain forest. Because the lizards' bodies require sunlight to gain heat, tree harvesting can cause a population increase. This would enhance the lizards' predation on other species, causing a cascade effect on forest community structure.

Milling quality of rice (Oryza sativa L.) is a primary factor determining its economic value in the U.S. market. It is largely influenced by genotype and environmental conditions prior to harvest. To determine the effect of environment on milling quality of rice genotypes, seven cultivars were evaluated for grain fissuring and milling yield at decreasing grain moisture during 1991 to 1993. Environmental factors, including air temperature, relative humidity, and rainfall, were monitored during grain maturity and drying period. Harvesting was carried out at 2- to 4-d intervals as grain moisture decreased from 270 to 130 g [kg.sup.-1]. High daily minimum relative humidity of 58% and mild temperatures during 1992 caused no significant fissuring until average harvest moisture decreased to 169 g [kg.sup.-1]. Warmer and drier weather during 1993 test period, with 43% daily minimum relative humidity, caused fissuring to be initiated earlier at a higher grain moisture of 184 g [kg.sup.-1]. With decreasing harvest moistures, head rice yield among all cultivars continued to increase until grain moisture was low enough for fissuring to occur. The optimum harvest moisture with respect to maximum head rice yield among long-grain cultivars, except for 'Lemont', ranged between 179 and 151 g [kg.sup.-1] during 1991-1993. Within this range, the optimum harvest moisture was highly dependent upon cultivars and environmental conditions. Cultivars with susceptibility to fissuring require higher harvest moistures for maximum milling performance. Optimum harvest moisture among years in grams per kilogram ranged between 200 to 176 for Lemont and 238 to 179 for medium-grain 'Bengal'. Despite the strong influence of weather conditions on rice milling yield, certain cultivars, such as 'Cypress' and 'L-202', have shown significant resistance to severe environmental fluctuations. Slow drying and fissuring resistance characteristics of Cypress grains provide flexibility in harvesting, transporting, and processing and preserve milling quality.

Forest harvesting and regeneration may cause changes in soil and solution chemistry that adversely affect environmental quality. Organic C content in the forest floor and mineral soil, and dissolved organic carbon (DOC) fractions in the soil solution and groundwater were investigated in a black spruce [Picea mariana (Miller) BSP] swamp 5 yr after the application of two silvicultural prescriptions: whole-tree harvest only and whole-tree harvest followed by site preparation bedding. Soil organic carbon (SOC) content in the forest floor of both treatments were significantly lower than that of an uncut control stand. However, SOC in the upper 50 cm of mineral soil of the bedded treatment was similar to that of the control, while both were about 20% higher than SOC in the harvest-only treatment. Total DOC concentrations ranged from 12 to 87 mg/L in the soil solution and 6 to 46 mg/L in the groundwater and did not differ among treatments. Hydrophobic acids were the dominant DOC fraction across all treatments, but the proportion of hydrophobic strong acids increased at the expense of hydrophilic acids in the harvest-only treatment. Carboxyl content of hydrophilic acids in the soil water was 7.0 mmol/g hydrophilic compound in the control stand and 4.4 mmol/g in the treatments. Hydrophobic acid carboxyl content across treatments was 4.6 mmol/g hydrophobic substance. Relative to C loss and changes in water chemistry, these results indicate that 5 yr after whole-tree harvesting, this forest site has not yet fully equilibrated.

A tree population growth matrix provides models of sustainable harvest for a Nigerian rain forest. Between 50 and 80% of the marketable trees will be retained with a cutting cycle of 36 and 54 years. This indicates that the present over-exploitation of the wood resource of the rain forest is 20% to 50%. Non-selective logging causes a reduction in diameter limits and increase in quantities of trees for logging. The logging costs are more and damage of the trees is less in selective logging but it is vice versa in non-selective logging.