A new method for predicting vegetation distributions using decision tree analysis in a geographic information system

Decision tree analysis was used to predict the distribution of forest communities in an area on the south coast of New South Wales, Australia. The analysis was carried out using a geographical information system environmental data base of those topographic and geological variables thought to influence the distribution of vegetation and derived from cartographic sources. The resulting maps of forest communities are of a resolution sufficient to delimit individual forest stands and contain much ecological information.     

Wild pig populations in the National Parks

Populations of introduced European wild boar, feral pigs, and combinations of both types (all Susscrola L.) inhabit thirteen areas in the National Park Service system. All parks have relatively stable populations, with the exception of Great Smoky Mountains National Park, which reported a rapidly expanding wild boar population. Suspected and documented impacts were apparently related to pig densities and sensitivity of the ecosystem; the three largest units with dense wild pig populations reported the most damage. Overall, wild pigs are a relatively minor problem for the Park Service; however, problems are severe in at least three parks, and there is potential for invasion of wild boars into several additional parks in the Appalachian Mountains. More specific information is needed on numbers of wild pigs and their impacts in the various parks.     

Landscape design,planning, and management: An approach to the analysis of vegetation

The process of analyzing vegetation in terms of its suitability for various non-consumptive uses is primitive in comparison with systems for evaluating other resources such as soil and topography. This paper proposes a framework for developing a standardized, quantitative vegetation analysis system based on plant ecology methods. A tentative scheme under study in Wisconsin is presented for discussion purposes.     

青藏高原冬季积雪与河北省夏季降水

应用青藏高原地面站积雪观测资料,ＮＯＡＡ卫星观测积雪面积和美国宇航局微波遥感积雪深度等资料进行综合对比分析,确定了青藏高原冬季积雪的年际变化,在此基础上讨论了青藏高原冬季积雪状况对河北降水的影响。结果表明,青藏高原冬季多雪时,当年河北夏季降水往往偏少;青藏高原冬季少雪时,河北夏季降水往往偏多。     

Participatory Development of No-tillage Systems without Herbicides for Family Farming: The Experience of the Center-South Region of Paraná

It is currently estimated that 40 million hectares worldwide are cultivated through no-tillage systems (Derpsh, 1998). Small family farms account for less than 50,000ha, half of them located in South America's Southern Cone (Wall, 1998). Many hypotheses have been offered to explain why so few small farmers have adapted to this method. The most simplistic ones relate this limited adoption to small farmers' traditionalism and to their rejection of innovation. Others point to the low technological development of animal-drawn equipment needed for this technology or the low educational level of family farmers.Results of work done in the Center-South of Paraná, Southern Brazil, by AS-PTA¹ in partnership with the region's Forum of Family Farmers Organizations, challenge these hypotheses and draw attention to the need for new approaches and processes of research and extension if the goal is to disseminate and implement appropriate no-tillage systems among family farmers. One requisite is to lower production costs of this method through elimination of herbicides and using green manure and cover crops that shift the crop-weed balance in favor of crops.     

Land-Cover Assessment of Conservation and Buffer Zones in the BOSAWAS Natural Resource Reserve of Nicaragua

The BOSAWAS Natural Resource Reserve of Nicaragua was established in 1991, to protect a portion of the remaining tropical rain forest and to promote the sustainable use of the region's resources. Information required to effectively manage the reserve includes the extents and locations of present land-cover types and recent land-cover changes in the management use zones that were delineated by local indigenous communities. These zones include areas designated for conservation, limited resource extraction, agriculture, and watershed protection. Land-cover for 1986 and 1995 was identified for three of the communities from remotely sensed images and then input into a geographic information system database to identify land-cover types within these management use zones. For both dates of the analysis, advanced forest was the dominant land cover, with the conservation zones entirely forested. The amount of both agricultural land and scrub/early secondary forest increased between the two dates, with much of these land-cover classes occurring in the agriculture zones. Conflicts between the land-cover present and designated use were identified in some of the limited-use buffer and watershed protection zones. Changes between 1986 and 1995 were identified by overlaying the two land-cover data sets. Three change processes were identified as occurring: deforestation, reforestation, and reconversion. Changes were concentrated in the agriculture zones but were found to occur in every type of zone, except for conservation. The results of this study will establish baseline information for the future management of the BOSAWAS Reserve, an important component in uniting conservation areas along the Central American isthmus.     

Landscape Changes in the Mullica River Basin of the Pinelands National Reserve,New Jersey,USA

In 1979, the Pinelands Commission was established as a regional land-use planning and regulatory agency charged with the implementation of a Comprehensive Management Plan (CMP) for the Pinelands National Reserve (New Jersey, USA). The CMP was created to balance land preservation and development interests in the Reserve. Because water-quality degradation from developed and agricultural landscapes is associated with changes in the composition of biological communities, monitoring landscape changes provides one of the most direct measures of the impact of land-use policies on the Pinelands ecosystem. In this study, we prepared detailed, land-cover maps within randomly selected aerial-photograph plots for a major watershed in the Reserve. We used these land-cover maps to quantify changes in landscape composition and structure (i.e., patch size, patch area, and number of patches) and characterize land-cover transitions in the basin between 1979 and 1991. Because the study period represented the first 12 years of the regional-planning effort in the Reserve, we evaluated the relationship between land-cover transitions and Commission management-area designations which permit different land-use intensities. Although the landscape composition was similar in 1979 and 1991, we found an increase in the total area and number of developed-land, managed-grassland, and barren-land patches. An increase in the number of patches and a decrease in the total area and median and third-quartile patch sizes for forest land and for all patches regardless of cover type indicated that fragmentation of forest land and the landscape as a whole occurred during the study period. The major land-cover transitions that occurred during the period were the loss of forest land to development and associated cover types and the conversion of one agricultural type to another. Overall, land-cover transitions during the period were found to be consistent with the Commission management-area designations, which indicated that the regional-planning effort has been successful in directing human activities to appropriate areas of the basin.     

翻车机通风除尘系统

介绍一种冲突网除尘器，其具有原理独特，体积小，重量轻，能耗低，除尘效率高等特点，辞别适合翻车机除尘。运用表明，岗位粉尘浓度3．8mg/m^3，外排粉尘浓度40mg/m^3，除尘效率96％。     

Vegetation dynamics in impounded marshes along the Indian River Lagoon,Florida, USA

Data are presented on the vegetation dynamics of two impounded marshes along the Indian River Lagoon, in east-central Florida, USA. Vegetation in one of the marshes (IRC 12) was totally eliminated by overflooding and by hypersaline conditions (salinities over 100 ppt) that developed there in 1979 after the culvert connecting the marsh with the lagoon was closed. Over 20% recovery of the herbaceous halophytesSalicornia virginica, S. bigelovii, andBatis maritima was observed at that site after the culvert was reopened in 1982, but total cover in the marsh remains well below the original 75%. No recovery of mangroves was observed at this site. The second site (SLC 24), while remaining isolated from the lagoon during much of the study, did not suffer the complete elimination of vegetation experienced at the first site. At this location, mangroves increased in cover and frequency with a concomitant decrease in herbaceous halophytes. Considerable damage to the vegetation was evident at IRC 12 when the impoundment was closed and flooded for mosquito control in 1986. Although the damage was temporary, its occurrence emphasizes the need of planning and constant monitoring and adjustment of management details as conditions within particular marshes change. Storms and hurricanes may be important in promoting a replacement of black mangroves by red mangroves in closed impoundments because the former cannot tolerate pneumatophore submergence for long periods of time. University of Florida-IFAS Journal Series R-00521.     

Target and nontarget discrimination of herbicides applied to vegetation in a power-line corridor

We tested two cutting regimens (cut/spray and cut/delay spray) and four radiarc-applied herbicides (Garlon + Tordon, Accord, Accord + Escort, and Krenite) in an Ohio power-line corridor to determine which management combination best eliminated target species (i.e., trees) and preserved nontarget species (i.e., low shrubs, vines, perennial herbs, and grasses). When spraying was delayed after cutting, the herbicide with the least impact on nontarget species (Krenite) also was least efficient at killing target trees. Spraying soon after cutting improved tree-killing efficiency of several herbicides, but it also increased the negative impact on nontarget species. The herbicide with the most consistent tree-killing ability (Accord + Escort) had the most impact on nontarget species. Because none of the herbicide/cutting treatments performed ideally, resource managers must decide the acceptable impact on nontarget species when considering herbicide use. Future success of herbicides as part of an integrated succession management approach requires more selective application methods and formulations so that target effects can be maximized and nontarget effects can be minimized.