In:
Soil Science Society of America Journal, Wiley, Vol. 53, No. 4 ( 1989-07), p. 1222-1228
Abstract:
Moisture and nutrient conditions are poorly characterized in soils at elevations 〉 1500 m in the southern Appalachian Mountains. In the Black Mountains, high elevation soils are Typic and Lithic Haplumbrepts, with umbric epipedons that are extremely acid, organic‐rich, rocky, and unstable due to the steep slopes. Many of the Umbrepts in the Black Mountains have been disturbed by exploitative logging, repeated wildfires, and depredation by the balsam woolly adelgid ( Adelges piceae Ratzeburg), each of which has caused major fluctuations in C, nutrient, and hydrologic cycles of soils and ecosystems. The objective of this study was to evaluate predictions based on climate, forest disturbance, and soil genesis: that these soils are rarely subjected to low water potential, that soil N mineralization rates are currently high, and that availability of soil nutrient cations is low. A water balance model appropriate for soils with average water‐holding characteristics indicated that, on a 6‐yr recurrence interval, plants deplete soil moisture to 〈 ‐0.2 MPa during low rainfall periods of one‐month duration. High rock contents (about 0.40 m 3 /m 3 of soil volume in 40‐cm depth) limit soil water storage capacity, and make the spruce‐fir forests very dependent on regular rainfall supplies. Soil N appears mineralizable at moderately high rates, as indicated by three soil and plant indices of N availability, whereas plant availability of Ca and Mg appears marginal. Exchangeable Ca and Mg total only 6.4 and 3.4 kmol c /ha, respectively, in the surface 40 cm of mineral soil, low contents that indicate rapid rates of biogeochemical cycling of divalent cations in these ecosystems. The long‐term recovery of these soils from 20th century disturbances depends directly on the dynamics of soil organic matter, due to organic matter's susceptibility to disturbance and to its control over soil moisture and nutrient availability.
Type of Medium:
Online Resource
ISSN:
0361-5995
,
1435-0661
DOI:
10.2136/sssaj1989.03615995005300040039x
Language:
English
Publisher:
Wiley
Publication Date:
1989
detail.hit.zdb_id:
241415-6
detail.hit.zdb_id:
2239747-4
detail.hit.zdb_id:
196788-5
detail.hit.zdb_id:
1481691-X
SSG:
13
SSG:
21
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