LONG-TERM PATTERNS OF WATER QUALITY IN A MANAGED WATERSHED IN OREGON: 1. SUSPENDED SEDIMENT1

The cumulative effects of forest management activities on water quality at a downstream point were monitored from 1972-1980 during development of a watershed for timber resources. Suspended sediment concentration and turbidity were measured at two hydrologic stations which bracketed a 10-km reach of the Middle Santiam River in the Western Cascades of Oregon as it flowed through an 8000-ha block of intensively managed forest land. Slope failures often accompany road building and harvesting in steep forested watersheds and pose the most serious threat to water quality. Although 180 km of road were constructed and 3400 ha of old-growth forests were harvested from slopes averaging over 60 percent, long-term changes in sediment yields remained undetectable during the period of measurement. The geologic characteristics of the basin and the road construction and maintenance techniques as prescribed by Oregon's forest practice regulations helped to minimize the occurrence of slope failures so that long-term changes in suspended sediment export rates did not occur. Throughout the nine-year measurement period, seven slope failures which added sediment directly to streams produced measurable short-term responses at the downstream sampling location, but these erosion events were too small and too infrequent to produce long-term changes in sediment yield from the watershed.     

OXIDIZED NITROGEN IN PRECIPITATION,THROUGHFALL, AND STREAMFALL FROM A FORESTED WATERSHED IN OKLAHOMA1

ABSTRACT: Oxidized nitrogen (nitrite + nitrate N) concentrations were measured from bulk precipitation, bulk through-fall, and streamflow in a 7.86 hectare forested watershed in southeastern Oklahoma during the wet season from March through June 1983. Oxidized nitrogen inputs comparable to results of other studies were recorded during the 19 rainstorms sampled. Oxidized nitrogen concentrations appeared to increase after rainfall interacted with the pine and hardwood canopies and were inversely related to both rainfall and through-fall depth. Oxidized N concentrations in streamflow were greatest during the rising limb of storm flow with subsequent decreases during the falling limb of storm hydrographs and lowest during base flow. The oxidized N inputs from bulk precipitation were considerably greater than outputs from streamflow resulting in a net retention of oxidized nitrogen within the watershed during the study period.     

WATER QUALITY FROM TWO SMALL FORESTED WATERSHEDS IN SOUTHERN ILLINOIS1

Two intermittent streams on oak-hickory watersheds in southern Illinois were gaged with a V-notched weir and sampled with an automatic water sampler. For three years data were collected on flow volume and water quality. Flow volumes show large variations between years and watersheds. Samples were analyzed for Na⁺, K⁺, Ca⁺⁺, Mg⁺⁺, P, and NO^-₃. Water quality was consistently high, although there were significant differences between watersheds. A baseline for water quality has been established for comparison after one of the watersheds is clearcut at a later date.     

秦皇岛市森林生态系统现状分析

通过分析秦皇岛市当前森林生态系统的现状、效益,发现秦皇岛市森林生态系统存在着分布不均、林龄结构不合理等问题;提出了退耕还林、封山育林、加大宣传力度等措施,以期秦皇岛森林生态系统走上可持续发展的道路,更好地造福于人民。     

张家界气候资源的利用与保护

为了充分开发利用和保护张家界的气候资源,我们采用长期定点和短期定位相结合的方法,观测研究了张家界的气候和森林小气候特征。研究证明,张家界具有亚热带湿润季风气候区的山地气候特征,森林小气候舒适宜人,旅游气候资源和农业气候资源丰富,应大力发展旅游业和林业;保护森林植被是保护张家界气候资源的关键。     

江西山地森林资源的保护与合理开发

江西省是我国南方山地森林资源丰富的省份之一。本文详细分析了江西山地森林资源的现状和存在的问题,并就山地森林的保护和合理开发利用提出了6项综合治理措施。     

气象产品及其商品化的理论与实证分析

本文创造性地把气象产品分类为气象新能源产品、气象信息服务业和咨询业产品、一般气象服务产品和气象业附属产品四种类型,从多角度进行了气象产品商品化可行性问题的理论和事实论证;并对比中国与世界气象产品商品化的现状,提出了实现气象产品商品化所必须具备的一系列条件     

EROSION ON LOGGING ROADS IN REDWOOD CREEK,NORTHWESTERN CALIFORNIA1

Road-related erosion was estimated by measuring 100 randomly located plots on a 180 km road network in the middle reach of R'dwood Creek in northwestern California. The estimated erosion ratn of 177 m³ km^-1 was contrasted with two earlier studies in nearby parts of the same watershed. A sizable proportion of the great reduction in erosion from that reported in the earlier studies is attributed to changes in forest practice rules. Those changes have resulted in better placement and sizing of culverts and, especially, to less reliance on culverts to handle runoff from logging roads.     

An evaluation of resource inventory and monitoring program used in national forest planning

The National Forest Management Act (1976) specifies that multiresource inventories be conducted to provide baseline data for development and, later, monitoring of national forest management plans. This mandate entails the most ambitious and complex resource planning effort ever attempted. In this paper we evaluate the structure and use of current inventory-monitoring programs and recommend a framework for gathering data to improve national forest planning. Current national guidelines are general and provide only basic directions to forest-level planners. Forest inventories have traditionally concentrated on timber. Although these inventories are often well designed, the questions we are now asking about forest resources have outgrown these methods. Forest management is impeded by general confusion over definitions of resources and the interactions among them. We outline a simple classification scheme that centers on identification of basic ecosystem elements that can be readily measured. Furthermore, spatial and temporal scales must be considered in the design of inventory-monitoring programs. The concept of ecological indicators is reviewed, and caution is advised in their use. Inventory-monitoring programs should be goal-directed and based on as rigorous a statistical design as possible. We also review fundamental issues of variable selection, validation, and sampling bias. We conclude by developing a flexible inventory-monitoring program that is designed to provide information on individual characteristics of the environment, rather than being based on fixed definitions of resources.