Báo cáo lâm nghiệp: Standing crop, production, on dry, moderate, and wet

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Báo cáo lâm nghiệp: "Standing crop, production, on dry, moderate, and wet" and turnover of fine roots Standing crop, production, sites of mature Douglas-fir on dry, moderate, and wet in western Oregon R.K. HERMANN D. SANTANTONIO Production Forestry Div ivision, Forest Research Ins Forest Research Inslitute, Private Rag, Rolorua, New Zealand Departments of Forest Science and Forest Management, Oregon 973’S1 LlSA Orl’!?on State Unimr.sity, Cf!t’f Introduction 1. Quantitative data on growth of roots in fcrests arc extremely limited. L.Y R& H (1967), K et al. (1968), F (1968), S (1969, I98O), OFFMANN OSTLER AYLE UTTONHEAD (1973), RiEnACKE (1976), H (1977), R (1977), C (1979), R ERMANN USSELL ALDWELLand PERRY (1982) have reviewed the ’broad spectrum of literature pertaining to growthof tree roots. Despite this considerable body of information, our general understandingof roots lags far behind that of shoots. Previous investigations of root growth usuallyhave been limited to seedlings or young trees grown in isolation. The relatively fewstudies of roots in forests have been hampered by serious technical difficulties. Seedlingsand young trees grown in isolation differ fundamentally from large trees in a forest ;we currently lack an adequate basis to extrapolate from one to the other. Direct attempts to estimate root production and turnover in forests have beenreported primarily within the last decade. These efforts to quantify stand productivitybelow ground have usually been part of large-scale ecosystem studies, such as thoseof the International Biological Program (HARRIS et a 1980). Results of these studies ., lindicate that fine-root dynamics are an important carbon pathway in temperate 0forest ecosystems (A el al., 1980 ; H el nl., 1980 ; P 1983, Focrt., is ARR GREN , ERSSON1983). Whereas fine-root production and turnover have been compared for coniferand deciduous stands (HARRIS et al., 1977 ; M at., 1982), stands of LAUGHERTY C etdifferent ages (K 1955 ; P 1978, 1979, 1980 a ; G al., 1981),iER ct R t_A, ALE , ERSSONand stands of different nutrient status (P 1980 b ; K & G 1981), the EYRS , ERSSON , RIEReffect of moisture stress has not been examined across a range of habitats withinthe same forest type. roNto ANTAN S et crl. (1977) estimated the standing crop of roots (< 5 mm diameterin late summer for Watershed 10, a 10.2-ha watershed of old-growth Douglas-fir(Pseudotsugu ; [Mirb.] Franco) in western Oregon. When they calculated 7 z/ /! f Mstanding crops for the major habitat types within this watershed, they found overtwice as much root material in the dry type along the ridgetops and upper south-facing slope as in the wet type along the stream and lower northfacing slope. Douglas-fir appeared to exhibit a different strategy of fine-root growth in the dry habitat thanin the wet one. Whether this difference reflected a higher overall standing crop ofsmall and fine roots in the dry habitat or differences in the periodicity of root growth unknown.was Little is known about how site conditions and the stage of stand developmentaffect growth and development of small and fine roots in forests. Attempts to corre-late changes in root growth directly to changes in environmental conditions have yieldedinconclusive results (L & H 1967 ; H 1977 ; R 1977). The ...